A plasma-coupled sulfate method for recovering ternary battery cathode materials

Abstract

This invention belongs to the field of secondary battery cathode material recycling technology. More specifically, it relates to a plasma-sulfate combined method for recycling ternary battery cathode materials. The specific recycling method of this invention includes: immersing the cathode sheet in the solvent N-methylpyrrolidone, ultrasonically treating it to separate the active material layer on the cathode sheet surface from the current collector aluminum foil, sieving to remove the separated current collector aluminum foil, obtaining the cathode material; transferring the cathode material into a microwave reactor, heating it to 450-500℃ in a nitrogen atmosphere, holding the temperature for 10-20 minutes, cooling, and discharging to obtain pyrolysis material; transferring the pyrolysis material to a plasma chamber, using a reducing gas as plasma, and plasma treating it for 20-30 minutes under conditions of a gas pressure of 50-60 Pa and a radio frequency power of 480-550 W to obtain reduced material; using a compound acid leaching solution as the leaching solution, mixing it with the reduced material, and acid leaching for 45-80 minutes to obtain the leaching solution.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery cathode material recycling technology. More specifically, it relates to a plasma-assisted sulfate-based method for recycling ternary battery cathode materials. Background Technology

[0002] While acid leaching is widely used in the recycling of ternary lithium-ion battery cathode materials (such as NCM / NCA), it still has several drawbacks, especially the low leaching efficiency.

[0003] In the acid leaching process, inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid can be used. However, this process is prone to the problem of co-dissolution of impurities, such as Fe, Al and Cu from the current collector or battery casing, which increases the difficulty of subsequent separation.

[0004] Organic acid leaching can also be used, such as citric acid, oxalic acid and malic acid. However, the leaching rate is slow during the leaching process, mainly because organic acids have poor reaction kinetics and are more expensive than inorganic acids.

[0005] Therefore, developing an efficient separation method and reducing the introduction of impurities during the recycling process is one of the technical challenges that still need to be overcome in this field.

[0006] The plasma-sulfate combined method for recycling ternary battery cathode materials is an efficient and environmentally friendly recycling strategy that combines low-temperature plasma technology and sulfate leaching process. It is mainly used to recover cathode materials such as nickel-cobalt-manganese (NCM) or nickel-cobalt-aluminum (NCA) in lithium-ion batteries. Summary of the Invention

[0007] The technical problem to be solved by this invention is: addressing the issues of slow leaching rate and low recovery rate in the existing acid leaching process for recovering ternary battery cathode materials, this invention provides a plasma-sulfate combined method for recovering ternary battery cathode materials.

[0008] The purpose of this invention is to provide a method for recovering ternary battery cathode materials using plasma-coupled sulfate.

[0009] The above-mentioned objective of this invention is achieved through the following technical solution:

[0010] A method for recovering ternary battery cathode materials using plasma-enhanced sulfate recovery, the specific recovery method including:

[0011] Cathode material stripping:

[0012] The positive electrode sheet is immersed in the solvent N-methylpyrrolidone and ultrasonically treated to separate the active material layer on the surface of the positive electrode sheet from the current collector aluminum foil. The separated current collector aluminum foil is then removed by sieving to obtain the positive electrode material.

[0013] Microwave pyrolysis:

[0014] The positive electrode material is transferred into a microwave reactor and heated to 450-500℃ in a nitrogen atmosphere with a microwave power of 1500-2000W. After holding the temperature for 10-20 minutes, the material is cooled and discharged to obtain the pyrolysis material.

[0015] Plasma treatment:

[0016] The pyrolysis material is transferred to a plasma chamber, where a reducing gas is used as plasma. The plasma is treated for 20-30 minutes at a pressure of 50-60 Pa and a radio frequency power of 480-550 W to obtain the reduced raw material.

[0017] Acid leaching treatment:

[0018] Using a compound acid leaching solution as the leachate, it is mixed with the reducing material and then subjected to acid leaching reaction at a temperature of 50-60℃ for 45-80 minutes to obtain the leachate.

[0019] In the compound acid leaching solution, the concentration of sulfuric acid is 1-1.2 mol / L, the concentration of citric acid is 0.1-0.15 mol / L, the concentration of ammonium sulfate is 0.08-0.10 mol / L, and the concentration of sodium fluoride is 0.03-0.05 mol / L.

[0020] The beneficial effects of the above technical solution include:

[0021] In the recycling process, the core advantage of plasma treatment lies in its low reaction temperature, typically below 200℃, which avoids the high energy consumption problem caused by high-temperature pyrolysis. Furthermore, plasma treatment can selectively activate the material surface without damaging the overall morphology. Specifically, reducing plasma, such as hydrogen or a hydrogen-containing mixture, is used to reduce metal oxides to elemental metals or lower valence states, improving subsequent leaching efficiency. During the leaching process, sulfuric acid is used as the main leaching agent, supplemented with sulfate additives, such as ammonium sulfate, to enhance metal leaching rates by forming ammonium salt complexes. Citric acid, in addition to acting as a supplementary complexing agent, also provides a weakly reducing environment. Sodium fluoride is used to inhibit aluminum dissolution.

[0022] However, the inventors discovered that if plasma treatment is performed directly, the presence of residual PVDF binder inside will affect the subsequent leaching efficiency. Microwave pyrolysis can decompose PVDF and reduce its adverse effects on the subsequent acid leaching process. More importantly, the inventors discovered that microwave pyrolysis can destroy the structure of the ternary material during the process, generating porous or amorphous substances, thereby improving the subsequent leaching efficiency.

[0023] Furthermore, the stripping of the positive electrode material also includes:

[0024] The positive electrode sheet is preheated to 200-220℃, and then immersed in the solvent N-methylpyrrolidone while hot. It is then subjected to ultrasonic treatment at 140-160℃ and 180-200kHz for 40-60 minutes to separate the active material layer on the surface of the positive electrode sheet from the current collector aluminum foil. The separated current collector aluminum foil is then removed by sieving to obtain the positive electrode material.

[0025] Furthermore, the specific recycling method also includes:

[0026] Cathode material stripping:

[0027] The positive electrode sheet is preheated to 200-220℃, and then immersed in the solvent N-methylpyrrolidone while hot. It is then subjected to ultrasonic treatment at 140-160℃ and 180-200kHz for 40-60 minutes to separate the active material layer on the surface of the positive electrode sheet from the current collector aluminum foil. The separated current collector aluminum foil is removed by sieving, and the remaining active material is dried until the N-methylpyrrolidone residue rate is 4-6% to obtain the positive electrode material.

[0028] The drying process is carried out under vacuum conditions of 80-100 Pa and temperature of 100-120 °C.

[0029] The beneficial effects of the above technical solution include:

[0030] Before microwave treatment of the cathode material, a portion of the solvent N-methylpyrrolidone is left inside, allowing it to participate in the microwave treatment reaction. During this process, on the one hand, the polar molecular structure of N-methylpyrrolidone can significantly absorb microwave energy and convert it into heat energy, accelerating the heating process of the cathode material, especially at low temperatures (below 200℃), where the microwave absorption capacity of N-methylpyrrolidone is superior to that of ternary cathode materials. The rapid heating brought by N-methylpyrrolidone can form local high-temperature regions in the material pores, promoting the full decomposition of the PVDF binder inside. On the other hand, under high-temperature conditions, N-methylpyrrolidone can decompose into reducing gas, thereby partially reducing the internal metal elements, reducing the difficulty of subsequent leaching. More importantly, the decomposed gas can form mass transfer channels, increasing the specific surface area of ​​the material, thereby improving the subsequent leaching efficiency.

[0031] Furthermore, the reducing gas is a mixture of argon and hydrogen in a volume ratio of 9:1.

[0032] Furthermore, the acid leaching treatment also includes:

[0033] Using a compound acid leaching solution as the leachate, it is mixed with reducing material at a mass ratio of 12-15:1, and then subjected to ultrasonic acid leaching reaction at a temperature of 50-60℃ and an ultrasonic frequency of 80-100kHz for 45-80 minutes to obtain the leachate.

[0034] Furthermore, the specific recycling method also includes:

[0035] Battery discharge and disassembly:

[0036] Place the battery in a 5-10% sodium chloride solution and soak it for 24-36 hours to discharge the battery.

[0037] Disassemble the discharged battery and collect the positive electrode plate.

[0038] Furthermore, the specific recycling method also includes:

[0039] Selective precipitation for impurity removal:

[0040] Add sodium hydroxide solution to the leachate to adjust the pH to 3.0. Keep the mixture at 55-60℃ and stir for 30-40 minutes. Filter to remove the precipitate. Then add sodium sulfide solution with a concentration of 0.1-0.12 mol / L and continue to keep the mixture at 55-60℃ and stir for 30-40 minutes. Filter and collect the purified filtrate.

[0041] Furthermore, the specific recycling method also includes:

[0042] Solvent extraction and separation:

[0043] Primary extraction: Add 10-12% by volume of P204 extractant to the purified filtrate, and extract Fe and Al at pH 2.5 to obtain the primary raffinate aqueous phase;

[0044] Secondary extraction: Add 20-22% by volume of Cyanex 272 extractant to the primary raffinate aqueous phase, and selectively extract the Co-containing oil phase and the secondary raffinate aqueous phase at pH 5.0.

[0045] The oil phase containing Co was back-extracted with sulfuric acid solution to obtain a cobalt sulfate solution;

[0046] Tertiary extraction: Add 15-18% by volume of P507 extractant to the secondary raffinate aqueous phase, and selectively extract the Ni-containing oil phase and the tertiary raffinate aqueous phase at pH 6.5.

[0047] The Ni-containing oil phase was back-extracted with hydrochloric acid to obtain a nickel chloride solution.

[0048] Furthermore, the specific recycling method also includes:

[0049] After concentrating the aqueous phase of the tertiary raffinate to a Li concentration of 10 g / L, a saturated sodium carbonate solution at room temperature was added, and the mixture was stirred at 80-90℃ for 60-80 min. The mixture was then filtered to obtain lithium carbonate precipitate and a filtrate containing Mn. Detailed Implementation

[0050] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0051] Unless otherwise specified, all reagents and materials used in the following examples are commercially available. Example 1

[0052] Battery discharge and disassembly:

[0053] The battery was placed in a 5% sodium chloride solution and soaked for 36 hours to discharge it.

[0054] Disassemble the discharged battery and collect the positive electrode plate from the battery;

[0055] Cathode material stripping:

[0056] The positive electrode sheet is preheated to 200℃, and then immersed in the solvent N-methylpyrrolidone while hot. It is then subjected to ultrasonic treatment at 140℃ and 180kHz for 40 minutes to separate the active material layer on the surface of the positive electrode sheet from the current collector aluminum foil. The separated current collector aluminum foil is removed by sieving, and the remaining active material is dried until the N-methylpyrrolidone residue rate is 4%, thus obtaining the positive electrode material.

[0057] The drying is carried out under a vacuum of 100 Pa and a temperature of 120 °C. During the drying process, the drying time is adjusted based on the time required to dry to constant weight under these conditions to obtain the cathode material with the corresponding residual rate.

[0058] Microwave pyrolysis:

[0059] The positive electrode material was transferred into a microwave reactor and heated to 450°C in a nitrogen atmosphere with a microwave power of 1500W. After holding the temperature for 10 minutes, the material was cooled and discharged to obtain the pyrolysis material.

[0060] Plasma treatment:

[0061] The pyrolysis material was transferred to a plasma chamber, and plasma was applied using a reducing gas at a pressure of 50 Pa and a radio frequency power of 480 W for 20 min to obtain the reduced material.

[0062] The reducing gas is a mixture of argon and hydrogen in a volume ratio of 9:1;

[0063] Acid leaching treatment:

[0064] Using a compound acid leaching solution as the leachate, it was mixed with the reducing material at a mass ratio of 12:1, and then subjected to an ultrasonic acid leaching reaction at a temperature of 50℃ and an ultrasonic frequency of 80kHz for 45 minutes to obtain the leachate.

[0065] In the compound acid leaching solution, the concentration of sulfuric acid is 1 mol / L, the concentration of citric acid is 0.1 mol / L, the concentration of ammonium sulfate is 0.08 mol / L, and the concentration of sodium fluoride is 0.03 mol / L.

[0066] Selective precipitation for impurity removal:

[0067] Add sodium hydroxide solution to the leachate to adjust the pH to 3.0. Keep the mixture at 55°C and stir at 200 r / min for 30 min. Filter to remove precipitates containing ferric hydroxide and aluminum hydroxide. Then add sodium sulfide solution with a concentration of 0.1 mol / L. Continue to keep the mixture at 55°C and stir for 30 min. Filter to remove precipitates containing copper sulfide. Collect the purified filtrate.

[0068] Solvent extraction and separation:

[0069] Primary extraction: Add 10% by volume of P204 extractant to the purified filtrate and extract Fe and Al at pH 2.5 to obtain the primary raffinate aqueous phase;

[0070] Secondary extraction: Add 20% by volume of Cyanex 272 extractant to the primary raffinate aqueous phase, and selectively extract the Co-containing oil phase and the secondary raffinate aqueous phase at pH 5.0.

[0071] The oil phase containing Co was back-extracted with a sulfuric acid solution of concentration of 1 mol / L to obtain a cobalt sulfate solution;

[0072] Tertiary extraction: Add 15% by volume of P507 extractant to the secondary raffinate aqueous phase, and selectively extract the Ni-containing oil phase and the tertiary raffinate aqueous phase at pH 6.5.

[0073] The Ni-containing oil phase was back-extracted with 2 mol / L hydrochloric acid to obtain a nickel chloride solution;

[0074] After concentrating the aqueous phase of the tertiary raffinate to a Li concentration of 10 g / L, a saturated sodium carbonate solution at room temperature was added, and the mixture was stirred at 80 °C for 60 min. The mixture was then filtered to obtain lithium carbonate precipitate and a filtrate containing Mn.

[0075] Example 2

[0076] Battery discharge and disassembly:

[0077] The battery was placed in an 8% sodium chloride solution and soaked for 28 hours to discharge it.

[0078] Disassemble the discharged battery and collect the positive electrode plate from the battery;

[0079] Cathode material stripping:

[0080] The positive electrode sheet is preheated to 210℃, and then immersed in the solvent N-methylpyrrolidone while hot. It is then subjected to ultrasonic treatment at 150℃ and 190kHz for 50 minutes to separate the active material layer on the surface of the positive electrode sheet from the current collector aluminum foil. The separated current collector aluminum foil is removed by sieving, and the remaining active material is dried until the N-methylpyrrolidone residue rate is 5%, thus obtaining the positive electrode material.

[0081] The drying is carried out under a vacuum of 90 Pa and a temperature of 110 °C. During the drying process, the drying time is adjusted based on the time required to dry to constant weight under these conditions to obtain the cathode material with the corresponding residual rate.

[0082] Microwave pyrolysis:

[0083] The positive electrode material was transferred into a microwave reactor and heated to 480°C in a nitrogen atmosphere with a microwave power of 1800W. After holding the temperature for 15 minutes, the material was cooled and discharged to obtain the pyrolysis material.

[0084] Plasma treatment:

[0085] The pyrolysis material was transferred to a plasma chamber, and plasma was applied using a reducing gas at a pressure of 55 Pa and a radio frequency power of 500 W for 25 min to obtain the reduced material.

[0086] The reducing gas is a mixture of argon and hydrogen in a volume ratio of 9:1;

[0087] Acid leaching treatment:

[0088] Using a compound acid leaching solution as the leachate, it was mixed with the reducing material at a mass ratio of 14:1, and then subjected to an ultrasonic acid leaching reaction at a temperature of 55℃ and an ultrasonic frequency of 90kHz for 60 minutes to obtain the leachate.

[0089] The compound acid leaching solution contains sulfuric acid at a concentration of 1.1 mol / L, citric acid at a concentration of 0.12 mol / L, ammonium sulfate at a concentration of 0.09 mol / L, and sodium fluoride at a concentration of 0.04 mol / L.

[0090] Selective precipitation for impurity removal:

[0091] Add sodium hydroxide solution to the leachate to adjust the pH to 3.0. Keep the mixture at 58°C and stir at 200 r / min for 35 min. Filter to remove precipitates containing ferric hydroxide and aluminum hydroxide. Add 0.11 mol / L sodium sulfide solution and continue to keep the mixture at 58°C and stir for 35 min. Filter to remove precipitates containing copper sulfide and collect the purified filtrate.

[0092] Solvent extraction and separation:

[0093] Primary extraction: Add 11% by volume of P204 extractant to the purified filtrate and extract Fe and Al at pH 2.5 to obtain the primary raffinate aqueous phase;

[0094] Secondary extraction: 21% by volume of Cyanex 272 extractant was added to the primary raffinate aqueous phase, and selective extraction was performed at pH 5.0 to obtain the Co-containing oil phase and the secondary raffinate aqueous phase.

[0095] The oil phase containing Co was back-extracted with a sulfuric acid solution of concentration of 1 mol / L to obtain a cobalt sulfate solution;

[0096] Tertiary extraction: Add 16% by volume of P507 extractant to the secondary raffinate aqueous phase, and selectively extract the Ni-containing oil phase and the tertiary raffinate aqueous phase at pH 6.5.

[0097] The Ni-containing oil phase was back-extracted with 2 mol / L hydrochloric acid to obtain a nickel chloride solution;

[0098] After concentrating the aqueous phase of the tertiary raffinate to a Li concentration of 10 g / L, a saturated sodium carbonate solution at room temperature was added, and the mixture was stirred at 85 °C for 70 min. The mixture was then filtered to obtain lithium carbonate precipitate and a filtrate containing Mn.

[0099] Example 3

[0100] Battery discharge and disassembly:

[0101] The battery was placed in a 10% sodium chloride solution and soaked for 24 hours to discharge it.

[0102] Disassemble the discharged battery and collect the positive electrode plate from the battery;

[0103] Cathode material stripping:

[0104] The positive electrode sheet is preheated to 220℃, and then immersed in the solvent N-methylpyrrolidone while hot. It is then subjected to ultrasonic treatment at 160℃ and 200kHz for 60 minutes to separate the active material layer on the surface of the positive electrode sheet from the current collector aluminum foil. The separated current collector aluminum foil is removed by sieving, and the remaining active material is dried until the N-methylpyrrolidone residue rate is 6%, thus obtaining the positive electrode material.

[0105] The drying is carried out under vacuum of 80 Pa and temperature of 100 °C. During the drying process, the drying time is adjusted based on the time required to dry to constant weight under these conditions to obtain the cathode material with the corresponding residual rate.

[0106] Microwave pyrolysis:

[0107] The positive electrode material was transferred into a microwave reactor and heated to 500°C in a nitrogen atmosphere with a microwave power of 2000W. After holding the temperature for 20 minutes, the material was cooled and discharged to obtain the pyrolysis material.

[0108] Plasma treatment:

[0109] The pyrolysis material was transferred to a plasma chamber, and plasma was applied using a reducing gas at a pressure of 60 Pa and a radio frequency power of 550 W for 30 min to obtain the reduced material.

[0110] The reducing gas is a mixture of argon and hydrogen in a volume ratio of 9:1;

[0111] Acid leaching treatment:

[0112] Using a compound acid leaching solution as the leachate, it was mixed with the reducing material at a mass ratio of 15:1, and then subjected to an ultrasonic acid leaching reaction at a temperature of 60℃ and an ultrasonic frequency of 100kHz for 80 minutes to obtain the leachate.

[0113] In the compound acid leaching solution, the concentration of sulfuric acid is 1.2 mol / L, the concentration of citric acid is 0.15 mol / L, the concentration of ammonium sulfate is 0.10 mol / L, and the concentration of sodium fluoride is 0.05 mol / L.

[0114] Selective precipitation for impurity removal:

[0115] Add sodium hydroxide solution to the leachate to adjust the pH to 3.0. Keep the mixture at 60°C and stir at 200 r / min for 40 min. Filter to remove precipitates containing ferric hydroxide and aluminum hydroxide. Add 0.12 mol / L sodium sulfide solution and continue to keep the mixture at 60°C and stir for 40 min. Filter to remove precipitates containing copper sulfide and collect the purified filtrate.

[0116] Solvent extraction and separation:

[0117] Primary extraction: Add 12% by volume of P204 extractant to the purified filtrate and extract Fe and Al at pH 2.5 to obtain the primary raffinate aqueous phase;

[0118] Secondary extraction: 22% by volume of Cyanex 272 extractant was added to the primary raffinate aqueous phase, and selective extraction was performed at pH 5.0 to obtain the Co-containing oil phase and the secondary raffinate aqueous phase.

[0119] The oil phase containing Co was back-extracted with a sulfuric acid solution of concentration of 1 mol / L to obtain a cobalt sulfate solution;

[0120] Tertiary extraction: Add 18% by volume of P507 extractant to the secondary raffinate aqueous phase, and selectively extract the Ni-containing oil phase and the tertiary raffinate aqueous phase at pH 6.5.

[0121] The Ni-containing oil phase was back-extracted with 2 mol / L hydrochloric acid to obtain a nickel chloride solution;

[0122] After concentrating the aqueous phase of the tertiary raffinate to a Li concentration of 10 g / L, a saturated sodium carbonate solution at room temperature was added, and the mixture was stirred at 90 °C for 80 min. The mixture was then filtered to obtain lithium carbonate precipitate and a filtrate containing Mn.

[0123] Example 4

[0124] The difference between this embodiment and Embodiment 1 is as follows:

[0125] Cathode material stripping:

[0126] The positive electrode sheet is preheated to 200℃, and then immersed in the solvent N-methylpyrrolidone while hot. It is then subjected to ultrasonic treatment at 140℃ and 180kHz for 40 minutes to separate the active material layer on the surface of the positive electrode sheet from the current collector aluminum foil. The separated current collector aluminum foil is removed by sieving, and the remaining active material is dried to constant weight to obtain the positive electrode material.

[0127] The drying process is carried out under a vacuum of 100 Pa and a temperature of 120 °C.

[0128] All other conditions remain unchanged.

[0129] Comparative Example 1

[0130] The difference between this comparative example and Example 1 is that microwave pyrolysis treatment was not used, while the other conditions remained unchanged.

[0131] Comparative Example 2

[0132] The difference between this comparative example and Example 1 is as follows:

[0133] The conventional heating pyrolysis process is used instead of microwave pyrolysis. Specifically:

[0134] Conventional heating pyrolysis:

[0135] The cathode material is transferred into a tube furnace and heated to 480°C in a nitrogen atmosphere. After holding the temperature for 15 minutes, it is cooled and discharged to obtain the pyrolysis material.

[0136] The recovery methods for the examples and comparative examples were evaluated, and the specific rating methods and evaluation results are as follows:

[0137] Aqua regia was used as the digestion acid to digest the cathode material before recycling. The contents of Li, Ni, Co and Mn in the cathode material were then tested by ICP-OES.

[0138] The contents of Co, Ni, and Mn in the cobalt sulfate solution, nickel chloride solution, and filtrate containing Mn obtained during the recovery process were determined by ICP-OES using the same method. The contents of the recovered lithium carbonate precipitate were determined by ICP-OES after digestion with aqua regia.

[0139] The recovery rate of the corresponding element is calculated based on the following formula:

[0140] Recovery rate = (Element content after recovery / Element content in the cathode material before recovery) × 100%;

[0141] Detailed test results are shown in Table 1:

[0142] Table 1: Recovery Rate Test Results

[0143]

[0144] As can be seen from the test results in Table 1, the technical solution of the present invention has a relatively higher recovery rate of elements in NCM cathode materials.

[0145] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for recovering ternary battery cathode materials using plasma-coupled sulfate treatment, characterized in that, Specific recycling methods include: Cathode material stripping: The positive electrode sheet is immersed in the solvent N-methylpyrrolidone and ultrasonically treated to separate the active material layer on the surface of the positive electrode sheet from the current collector aluminum foil. The separated current collector aluminum foil is then removed by sieving to obtain the positive electrode material. Microwave pyrolysis: The positive electrode material is transferred into a microwave reactor and heated to 450-500℃ in a nitrogen atmosphere with a microwave power of 1500-2000W. After holding the temperature for 10-20 minutes, the material is cooled and discharged to obtain the pyrolysis material. Plasma treatment: The pyrolysis material is transferred to a plasma chamber, where a reducing gas is used as plasma. The plasma is treated for 20-30 minutes at a pressure of 50-60 Pa and a radio frequency power of 480-550 W to obtain the reduced raw material. Acid leaching treatment: Using a compound acid leaching solution as the leachate, it is mixed with the reducing material and then subjected to acid leaching reaction at a temperature of 50-60℃ for 45-80 minutes to obtain the leachate. In the compound acid leaching solution, the concentration of sulfuric acid is 1-1.2 mol / L, the concentration of citric acid is 0.1-0.15 mol / L, the concentration of ammonium sulfate is 0.08-0.10 mol / L, and the concentration of sodium fluoride is 0.03-0.05 mol / L.

2. The method for recovering ternary battery cathode material using plasma-coupled sulfate extraction according to claim 1, characterized in that, The stripping of the cathode material also includes: The positive electrode sheet is preheated to 200-220℃, and then immersed in the solvent N-methylpyrrolidone while hot. It is then subjected to ultrasonic treatment at 140-160℃ and 180-200kHz for 40-60 minutes to separate the active material layer on the surface of the positive electrode sheet from the current collector aluminum foil. The separated current collector aluminum foil is then removed by sieving to obtain the positive electrode material.

3. The method for recovering ternary battery cathode material by plasma-coupled sulfate extraction according to claim 2, characterized in that, The specific recycling method also includes: Cathode material stripping: The positive electrode sheet is preheated to 200-220℃, and then immersed in the solvent N-methylpyrrolidone while hot. It is then subjected to ultrasonic treatment at 140-160℃ and 180-200kHz for 40-60 minutes to separate the active material layer on the surface of the positive electrode sheet from the current collector aluminum foil. The separated current collector aluminum foil is removed by sieving, and the remaining active material is dried until the N-methylpyrrolidone residue rate is 4-6% to obtain the positive electrode material. The drying process is carried out under vacuum conditions of 80-100 Pa and temperature of 100-120 °C.

4. The method for recovering ternary battery cathode material using plasma-coupled sulfate extraction according to claim 1, characterized in that, The reducing gas is a mixture of argon and hydrogen in a volume ratio of 9:

1.

5. The method for recovering ternary battery cathode material by plasma-coupled sulfate extraction according to claim 1, characterized in that, The acid leaching treatment also includes: Using a compound acid leaching solution as the leachate, it is mixed with reducing material at a mass ratio of 12-15:1, and then subjected to ultrasonic acid leaching reaction at a temperature of 50-60℃ and an ultrasonic frequency of 80-100kHz for 45-80 minutes to obtain the leachate.

6. The method for recovering ternary battery cathode material by plasma-coupled sulfate extraction according to claim 1, characterized in that, The specific recycling method also includes: Battery discharge and disassembly: Place the battery in a 5-10% sodium chloride solution and soak it for 24-36 hours to discharge the battery. Disassemble the discharged battery and collect the positive electrode plate.

7. The method for recovering ternary battery cathode material by plasma-coupled sulfate extraction according to claim 1, characterized in that, The specific recycling method also includes: Selective precipitation for impurity removal: Add sodium hydroxide solution to the leachate to adjust the pH to 3.

0. Keep the mixture at 55-60℃ and stir for 30-40 minutes. Filter to remove the precipitate. Then add sodium sulfide solution with a concentration of 0.1-0.12 mol / L and continue to keep the mixture at 55-60℃ and stir for 30-40 minutes. Filter and collect the purified filtrate.

8. The method for recovering ternary battery cathode material by plasma-coupled sulfate extraction according to claim 7, characterized in that, The specific recycling method also includes: Solvent extraction and separation: Primary extraction: Add 10-12% by volume of P204 extractant to the purified filtrate, and extract Fe and Al at pH 2.5 to obtain the primary raffinate aqueous phase; Secondary extraction: Add 20-22% by volume of Cyanex 272 extractant to the primary raffinate aqueous phase, and selectively extract the Co-containing oil phase and the secondary raffinate aqueous phase at pH 5.

0. The oil phase containing Co was back-extracted with sulfuric acid solution to obtain a cobalt sulfate solution; Tertiary extraction: Add 15-18% by volume of P507 extractant to the secondary raffinate aqueous phase, and selectively extract the Ni-containing oil phase and the tertiary raffinate aqueous phase at pH 6.

5. The Ni-containing oil phase was back-extracted with hydrochloric acid to obtain a nickel chloride solution.

9. The method for recovering ternary battery cathode material by plasma-coupled sulfate as described in claim 8, characterized in that, The specific recycling method also includes: After concentrating the aqueous phase of the tertiary raffinate to a Li concentration of 10 g / L, a saturated sodium carbonate solution at room temperature was added, and the mixture was stirred at 80-90℃ for 60-80 min. The mixture was then filtered to obtain lithium carbonate precipitate and a filtrate containing Mn.

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