Method for recovering and regenerating retired ternary lithium battery positive electrode material by using eutectic solvent

Abstract

The application relates to a method for recycling and regenerating retired ternary lithium battery positive electrode materials by using a deep eutectic solvent, and the technical scheme is as follows: first, a deep eutectic solvent (DES) aqueous solution is used for leaching retired ternary lithium battery positive electrode black powder, then water is added to precipitate nickel, cobalt and manganese, then the nickel, cobalt and manganese precipitate is calcined into a ternary lithium ion battery precursor, the lithium-rich filtrate is subjected to water removal and oxalic acid supplement, and then is recycled and used for positive electrode black powder leaching, after recycling and using, ethanol is added to obtain lithium hydrogen oxalate dehydrate precipitation, then concentrated sulfuric acid digestion and frozen crystallization are carried out to obtain high-purity LiOH, finally, the LiOH is mixed with the battery precursor, component regulation is carried out, and then a regenerated ternary battery positive electrode material is prepared. The application has the advantages of simple process, DES recycling and three-cycle process of green regeneration of ternary positive electrode materials, the first cycle charge-discharge efficiency of the regenerated battery is close to that of a commercial battery, and the regenerated ternary lithium battery shows good electrochemical performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of resource recycling science and engineering, and specifically relates to a method for recovering and regenerating retired ternary lithium battery positive electrode materials by using a eutectic solvent, and belongs to the technology of comprehensive disposal and resource utilization of bulk solid waste. BACKGROUND

[0002] Retired lithium batteries contain a large amount of valuable metal resources such as lithium, cobalt and nickel. These resources have a very high recycling value in the fields of new energy vehicles and energy storage systems. However, if the retired lithium batteries are not effectively recycled and treated, not only will it cause great waste of resources, but also will cause serious pollution to the environment; in addition, the increase of metal resources consumption required by lithium batteries is also unsustainable. Therefore, the recycling and treatment of retired lithium batteries has become a major issue to be solved at present.

[0003] Currently, there are mainly three kinds of recycling technologies for extracting metals from retired lithium ion batteries: pyrometallurgy, hydrometallurgy and direct recycling. Pyrometallurgical recycling of retired lithium batteries uses high temperature of 1200-1600℃ to melt the battery materials, and the metal recovery rate is as high as ~100%. In contrast, hydrometallurgy uses chemical solvents to leach target metals from retired lithium ion batteries more flexibly, and then extracts and purifies them. However, the hydrometallurgical technology has a long process route, and there are technical problems in separating elements with similar properties, and also produces a large amount of waste liquid and waste residue, which poses a risk to the environment. Although pyrometallurgy and hydrometallurgy have realized commercial scale application in the recycling of retired lithium batteries, there are still problems in economy and sustainability. Direct recycling, which retains the positive electrode crystal structure to directly regenerate battery components, is actually more attractive due to the reduction of energy consumption and waste. Direct recycling technology is mainly used for recycling retired LFP (lithium iron phosphate), and is still in laboratory and pilot scale. Due to the input chemical "sensitivity" and poor quality of the regenerated battery material, it is reported that the direct recycling technology has not been well developed, and there is no case of its industrialization. Therefore, it is of great significance and value to develop suitable green technology for sustainable recycling of retired lithium ion batteries.

[0004] Deep eutectic solvents (DESs) have attracted attention for the green recovery of spent lithium batteries due to their unique properties, including high metal selectivity, cost-effectiveness, and "greenness". The technical advantages of DESs, especially in terms of metal selectivity, solvent recyclability, and applicability to all types of apparent cathodes, not only eliminate the technical defects in current pyrometallurgical, hydrometallurgical, and direct recovery methods, but also make them more suitable for commercialization and development in the green battery industry. However, there are still some problems and difficulties in the current application of DESs for the green recovery of spent lithium-ion battery cathodes to obtain important metal resources, and one obstacle to its continuous development is to find a balance in the following three aspects: 1) achieving high metal leaching efficiency, 2) ensuring the greenness of DESs, and 3) promoting the reusability of DESs. SUMMARY

[0005] The present application aims to overcome the defects of the prior art, and the purpose is to provide a method for recycling and regenerating spent ternary lithium battery cathode materials using a deep eutectic solvent. The valuable metals Li, Ni, Co, and Mn recovered can be used to prepare ternary lithium battery cathode materials again, and the DES used in the recycling process can also be recycled. The present application can maintain high leaching rates and high recovery rates of Li, Ni, Co, and Mn, has low energy consumption and is environmentally friendly, and can also achieve the recycling and application of spent lithium battery cathode materials at the same time. It can not only effectively alleviate the problem of metal resource shortage caused by the rapid development of the lithium battery industry, but also reduce environmental pollution of spent lithium batteries.

[0006] To achieve the above purpose, the technical solution adopted by the present application is as follows:

[0007] S1, mix tetramethylammonium chloride with organic acid, stir at a constant temperature of 60-100℃ for 0.5-1h to obtain a clear and uniform deep eutectic solvent, referred to as DES; then mix the deep eutectic solvent with water to obtain a clear and uniform DES aqueous solution;

[0008] S2, add the cathode black powder to the DES aqueous solution, stir at a constant temperature of 60-100℃ for 0.5-1h, then add a certain amount of water, and after solid-liquid separation, obtain filtrate A and filter residue B; after washing and drying the filter residue B, calcine at a temperature of 500-600℃ for 3-6h, then naturally cool to room temperature, ball mill, and sieve to obtain battery precursor C1;

[0009] S3, to the filtrate A prepared in step S2, add anhydrous ethanol, then concentrate under reduced pressure at 70 DEG C until no condensate is precipitated, to obtain concentrated liquid D; to the concentrated liquid D, supplement the loss of organic acid, water, and then stir at constant temperature of 60-100 DEG C for 0.5-1 h to obtain a clear and uniform DES aqueous solution which is recycled for step S2; when recycled for 5-10 times, first add ethanol to the concentrated liquid D, and then solid-liquid separation to obtain lithium oxalate hydroxide precipitate and filtrate E, then remove ethanol from the filtrate E by rotary evaporation, and then supplement the loss of organic acid and water, and then stir at constant temperature of 60-100 DEG C for 0.5-1 h to obtain a clear and uniform DES aqueous solution which is recycled for step S2;

[0010] S4, to the lithium oxalate hydroxide precipitate prepared in step S3, add concentrated sulfuric acid, digest at constant temperature for 0.5-1 h, then adjust pH by adding 30% NaOH solution, then add NaOH solid, then freeze crystallize at-5 to-10 DEG C, and then solid-liquid separation, and then concentrate the filtrate to precipitate crystals, and then solid-liquid separation, and then wash and dry the filter cake to obtain battery precursor C2.

[0011] S5, mix the battery precursor C1 prepared in step S2 and the battery precursor C2 prepared in step S4, add corresponding Ni salt, Co salt and Mn salt according to the required proportion of ternary battery positive electrode to regulate the composition, then ball mill, sieve, then calcine in an oxygen atmosphere, cool to room temperature, then ball mill and sieve to obtain regenerated ternary battery positive electrode material, thereby realizing green regeneration of retired ternary lithium battery positive electrode material.

[0012] The sample preparation process of the positive electrode black powder is as follows: first, disassemble the retired ternary lithium battery into battery monomers, and then obtain positive electrode sheets after discharging, crushing and sorting; then cut the positive electrode sheets into small square pieces, soak in 0.5-2 mol / L NaOH solution at room temperature for 0.5-2 h, and then filter, wash and dry to obtain positive electrode material after removing impurity aluminum, and then calcine the positive electrode material after removing impurity aluminum in air atmosphere at 500-600 DEG C for 3-5 h to obtain positive electrode black powder; the ternary lithium battery refers to a lithium battery using lithium nickel cobalt manganese oxide as the positive electrode material, and is preferably one or more of NCM111, NCM523, NCM622 and NCM811.

[0013] The molar ratio of tetramethylammonium chloride to organic acid in the deep eutectic solvent is 2:1-1:4; the organic acid is oxalic acid; and the mass fraction of water in the DES aqueous solution is 0-30%.

[0014] The mass ratio of the DES aqueous solution to the positive electrode black powder is (30-60):1.

[0015] The water is added in step S2 in an amount of 3-5 times the mass of the DES aqueous solution; and the ethanol is added in step S3 in an amount of 8-10% of the amount of water added in step S2.

[0016] In step S4, the molar ratio of the amount of concentrated sulfuric acid added to the lithium hydroxide oxalate precipitate is 1.5-2.5, and the molar ratio of the amount of solid NaOH added to the battery precursor C2 is 1.0-1.1.

[0017] In step S5, the ball milling time is 5-10 h; the mesh size of the sieving is 200-400 mesh; and the calcination is first raising the temperature to 450-550℃ at a rate of 5℃ / min, then maintaining the temperature at 450-550℃ for 4-6 h, then raising the temperature to 780℃ at a rate of 5℃ / min, and then maintaining the temperature at 750-800℃ for 8-12 h.

[0018] When the DES aqueous solution is recycled for 5-10 times, the leaching rate of Li in the retired ternary lithium battery positive electrode material by the deep eutectic solvent is not less than 95%.

[0019] The leaching rates of Ni, Co and Mn in the retired ternary lithium battery positive electrode material by the deep eutectic solvent are all not less than 99.5%.

[0020] The regenerated ternary battery positive electrode material is used to prepare a regenerated ternary lithium battery, preferably a ternary lithium ion button cell, and when the electrolyte is 1 mol / L LiPF6, the initial charge capacity is not less than 180 mAh / g, the initial discharge capacity is not less than 170 mAh / g, the coulombic efficiency is not less than 95% after 50 cycles of charge and discharge, and the specific capacity is not less than 145 mAh / g.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] (1) The method for recycling and regenerating retired ternary lithium battery positive electrode material by using a deep eutectic solvent selects tetramethylammonium chloride and oxalic acid to prepare a deep eutectic solvent (DES), and the retired ternary lithium battery positive electrode black powder is leached by multiple cycles of recycling, which can realize high selectivity separation and high recovery rate of nickel, cobalt and manganese from lithium in the ternary positive electrode black powder, the DES system has good cycle performance, and the use cost of the DES can be significantly reduced.

[0023] (2) The method for recycling and regenerating retired ternary lithium battery positive electrode material by using a deep eutectic solvent, the presence of the hydrogen bond donor oxalic acid in the DES promotes the generation of H + , and the radius of Li + is smaller than that of H + , so Li +The ions are easily replaced by H protons, causing the Ni, Co, Mn ions inside the layered structure to be exposed to the DES solution, making it easier to dissolve and leach out; moreover, the reduction of oxalic acid can reduce the high-valence metal ions to low-valence ions, and the coordination of chloride ions can form [NiCl4] 2- , [CoCl4] 2- , [MnCl4] 2- When water is added, water will replace the coordination of Cl - , forming [Ni(H2O)6] 2+ , [Co(H2O)6] 2+ , [Mn(H2O)6] 2+ , which promotes the reaction with C2O4 2- to generate nickel, cobalt and manganese oxalate. These factors work together to achieve high selectivity separation of lithium, nickel, cobalt and manganese in DES.

[0024] (3) The method for recycling and regenerating retired ternary lithium battery cathode materials by using the eutectic solvent, using the recycled high-purity lithium hydroxide and nickel-cobalt-manganese ternary precursor, can prepare a regenerated ternary battery cathode material, and assemble a ternary lithium ion button cell. When the electrolyte is 1 mol / L LiPF6, the first circle charge-discharge efficiency of the regenerated ternary lithium battery is close to that of the commercial battery. After 50 charge-discharge cycles, the coulombic efficiency is not less than 95%, and the specific capacity is not less than 145 mAh / g, showing good electrochemical performance of the regenerated ternary lithium battery.

[0025] (4) The method for recycling and regenerating retired ternary lithium battery cathode materials by using the eutectic solvent has the advantages of DES recycling, double-circulation process of recycling nickel-cobalt-manganese and lithium to prepare ternary cathode materials, which can not only alleviate the problem of metal resource shortage caused by the rapid development of the lithium battery industry, but also reduce the environmental pollution of retired lithium batteries. BRIEF DESCRIPTION OF DRAWINGS

[0026] The drawings accompanying the specification of this application serve to provide further understanding of the present application, and the illustrative embodiments of the present application and their descriptions serve to explain the present application, and do not constitute an improper limitation on the present application.

[0027] Figure 1 X-ray diffraction pattern (XRD) of the battery precursor C1 prepared in step S2 of Example 1.

[0028] Figure 2 X-ray diffraction pattern (XRD) of the lithium oxalate hydroxide precipitate prepared in step S4 of Example 1.

[0029] Figure 3X-ray photoelectron spectroscopy (XPS) of Ni element in the retired ternary lithium battery anode material powder and the recovered nickel-cobalt-manganese oxalate of Example 1.

[0030] Figure 4 X-ray photoelectron spectroscopy (XPS) of Co element in the retired ternary lithium battery anode material powder and the recovered nickel-cobalt-manganese oxalate of Example 1.

[0031] Figure 5 X-ray photoelectron spectroscopy (XPS) of Mn element in the retired ternary lithium battery anode material powder and the recovered nickel-cobalt-manganese oxalate of Example 1.

[0032] Figure 6 The change curve of Li, Ni, Co, Mn leaching efficiency when the eutectic solvent prepared in Example 1 is used to leach the retired ternary lithium battery anode material powder at different temperature conditions.

[0033] Figure 7 X-ray diffraction (XRD) spectrum of the battery precursor C2 prepared in step S4 of Example 1.

[0034] Figure 8 X-ray diffraction (XRD) spectrum of the regenerated ternary battery anode material powder prepared in step S5 of Example 1.

[0035] Figure 9 The initial charge-discharge curve of the regenerated lithium ion button cell prepared in Example 1.

[0036] Figure 10 The coulombic efficiency and specific capacity curve of the regenerated lithium ion button cell prepared in Example 1 within 50 cycles. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present application clearer, further description will be made below in combination with specific embodiments, which are not limiting to the protection scope thereof. Unless otherwise specified, the raw materials and reagents used in the examples are commercially available; the reagents, instruments or operation steps not recorded in the text are routine determinations by those skilled in the art.

[0038] Example 1

[0039] A method for recycling and regenerating retired ternary lithium battery anode material by using a eutectic solvent, the specific implementation steps are as follows:

[0040] S0, disassemble the retired NCM811 lithium battery to battery monomer, get the positive plate after discharging, crushing and sorting; then cut the positive plate into small square pieces, soak in 1 mol / L NaOH solution at room temperature for 1 h, then filter, wash, dry, get the positive material after removing impurity aluminum, then calcine the positive material after removing impurity aluminum in air atmosphere at 500 ℃ for 4 h, get the positive black powder;

[0041] S1, add 10.9 g of tetramethylammonium chloride and 12.6 g of oxalic acid dihydrate into a 250 mL round-bottom flask, stir in a hydrothermal magnetic stirrer at constant temperature of 80 ℃ for 1 h, get a clear and uniform deep eutectic solvent (DES); then add 4.7 g of deionized water to the DES, stir at constant temperature of 80 ℃ for 0.5 h, get a clear and uniform DES aqueous solution;

[0042] S2, add 0.564 g of the positive black powder of the retired NCM811 battery to the DES aqueous solution, stir in a hydrothermal magnetic stirrer at constant temperature of 80 ℃ for 0.5 h, then add 100 mL of deionized water, stir for 0.5 h, then reduce pressure and filter, wash the filter residue B with water and ethanol in turn, then dry in an oven at 80 ℃, then calcine in a muffle furnace at 550 ℃ for 5 h, naturally cool to room temperature, then ball mill and sieve, get the battery precursor C1;

[0043] S3, add 10 mL of anhydrous ethanol to the filtrate A obtained by reducing pressure and filtering in step S2, then reduce pressure and concentrate in a rotary evaporator at 70 ℃ until no condensate is precipitated, get the concentrated solution D; supplement the lost organic acid and water to the concentrated solution D, stir at constant temperature of 80 ℃ for 0.5 h, get a clear and uniform DES aqueous solution, which is recycled for step S2; when recycled for 5 times, first add ethanol to the concentrated solution D, separate the solid and liquid, get the lithium oxalate hydroxide precipitate and the filtrate E, then remove the ethanol from the filtrate E by rotary evaporation, then supplement the lost organic acid and water, stir at constant temperature of 80 ℃ for 0.5 h, get a clear and uniform DES aqueous solution, which is recycled for step S2;

[0044] S4, add 98% concentrated sulfuric acid to the lithium oxalate hydroxide precipitate prepared in step S3, digest at constant temperature of 170 ℃ for 0.5 h, then add 30% NaOH solution to adjust pH to 7.5, then add NaOH solid, then freeze crystallize at -10 ℃, reduce pressure and filter, concentrate the filtrate at 70 ℃ in a rotary evaporator to precipitate crystals, then reduce pressure and filter, wash and dry the filter cake, get the battery precursor C2;

[0045] S5, 0.4006 g of battery precursor C1 prepared in step S2 and 0.2459 g of battery precursor C2 prepared in step S4 were mixed, and then the corresponding Ni salt, Co salt and Mn salt were added for component regulation according to NCM811, followed by ball milling for 10 h, sieving with a 400 mesh sieve, and then heating to 500 DEG C at a rate of 5 DEG C / min in a tube furnace under an oxygen atmosphere, holding at 500 DEG C for 5 h, then heating to 780 DEG C at a rate of 5 DEG C / min, and then holding at 780 DEG C for 10 h, followed by natural cooling to room temperature, ball milling for 5 h, and sieving with a 200 mesh sieve to obtain regenerated ternary battery cathode powder.

[0046] Figure 1 The powder XRD pattern of the battery precursor C1 prepared in step S2 of Example 1 is shown in the figure, the main diffraction characteristic peaks in the figure are consistent with standard card No. PDF #25-0582, 25-0250, 25-0544, and there are fewer impurity peaks, indicating that the prepared battery precursor C1 powder is a nickel-cobalt-manganese oxalate salt.

[0047] Figure 2 The powder XRD pattern of the lithium oxalate hydroxide precipitate prepared in step S4 of Example 1 is shown in the figure, the main diffraction characteristic peaks in the figure are consistent with standard card No. PDF #49-1209, and there are fewer impurity peaks, indicating that the prepared lithium oxalate hydroxide precipitate is pure phase lithium oxalate hydroxide tetrahydrate.

[0048] Figure 3 , Figure 4 and Figure 5 It is shown that the characteristic peaks and satellite peaks of cobalt and manganese elements located on the 2p orbital have changed significantly, specifically, the characteristic peaks of high-valence cobalt and manganese ions disappear in the XPS spectrum after leaching, and the position of the characteristic peaks of low-valence cobalt and manganese ions is shifted, indicating that the high-valence cobalt and manganese metals are reduced to low-valence cobalt and manganese ions after leaching.

[0049] Figure 6 It is shown that the DES described in Example 1 can achieve efficient leaching of lithium in the retired NCM811 lithium battery cathode powder.

[0050] Figure 7 The powder XRD pattern of the battery precursor C2 prepared in step S4 of Example 1 is shown in the figure, the main diffraction characteristic peaks in the figure are consistent with standard card No. PDF #76-1073, and there are fewer impurity peaks, indicating that the prepared battery precursor C2 is pure phase LiOH·H2O.

[0051] Figure 8 The XRD pattern of the regenerated ternary battery cathode powder prepared in step S5 of Example 1 is shown in the figure, the main diffraction characteristic peaks in the figure are consistent with standard card No. PDF #70-4314, and there are fewer impurity peaks, indicating that the prepared regenerated ternary battery cathode powder is an NCM811 battery cathode.

[0052] Figures 9-10 It is shown that the lithium ion button cell assembled with the regenerated ternary battery cathode prepared by step S of example 1 has stable electrochemical performance, and the electrochemical performance is close to that of the commercial NCM811 lithium ion battery.

[0053] Application Example 1

[0054] Assemble NCM811 lithium ion button cell: the mass ratio of regenerated ternary battery cathode powder, conductive agent (carbon black) and binder (PVDF) is 8:1:1, and the electrolyte is 1 mol / L LiPF6. After the NCM811 lithium ion button cell is assembled, it is left overnight, and its electrochemical performance is tested by an electrochemical workstation: the initial charge capacity is 180.46 mAh / g, and the initial discharge capacity is 171.73 mAh / g; after 50 charge-discharge cycles, the coulombic efficiency is maintained above 95%, and the specific capacity is 145.09 mAh / g.

[0055] Those skilled in the art should understand that the above description is only several specific embodiments of the present application, not all embodiments. It should be noted that many modifications and improvements can also be made by those of ordinary skill in the art, and all modifications and improvements that do not exceed the scope of the claims should be considered as the protection scope of the present application.

Claims

1. A method for recovering and regenerating retired ternary lithium battery cathode materials using a eutectic solvent, characterized in that, Specifically, the following steps are included: S1. Tetramethylammonium chloride is mixed with oxalic acid and stirred at a constant temperature of 60-100℃ for 0.5-1h to obtain a clear and homogeneous eutectic solvent, abbreviated as DES; then the eutectic solvent is mixed with water to obtain a clear and homogeneous DES aqueous solution. S2. Add positive electrode black powder to DES aqueous solution, stir at a constant temperature of 60-100℃ for 0.5-1h, then add a certain amount of water, and after solid-liquid separation, obtain filtrate A and filter residue B; after washing and drying filter residue B, calcine at 500-600℃ for 3-6h, and then naturally cool to room temperature, ball mill and sieve to obtain battery precursor C1; S3. Add anhydrous ethanol to the filtrate A prepared in step S2, and then concentrate it under reduced pressure at 70°C until no more condensate is precipitated to obtain concentrate D. Add the lost oxalic acid and water to concentrate D, and then stir at a constant temperature of 60-100°C for 0.5-1h to obtain a clear and homogeneous DES aqueous solution, which is recycled back to step S2. After recycling 5-10 times, first add ethanol to concentrate D, and after solid-liquid separation, obtain lithium oxalate precipitate and filtrate E. Then, remove the ethanol from filtrate E by rotary evaporation, and then add the lost oxalic acid and water, and stir at a constant temperature of 60-100°C for 0.5-1h to obtain a clear and homogeneous DES aqueous solution, which is recycled back to step S2. S4. Add concentrated sulfuric acid to the lithium oxalate precipitate prepared in step S3, digest at a constant temperature for 0.5 to 1 hour, then add 30% NaOH solution to adjust the pH, then add solid NaOH, and then freeze crystallize at -5 to -10℃. After solid-liquid separation, concentrate the filtrate to precipitate crystals, then perform solid-liquid separation again, wash and dry the filter cake to obtain battery precursor C2. S5. The battery precursor C1 prepared in step S2 and the battery precursor C2 prepared in step S4 are mixed, and the corresponding Ni salt, Co salt and Mn salt are added according to the proportion required for the ternary battery cathode to adjust the composition. Then, the mixture is ball-milled and sieved, and then calcined in an oxygen atmosphere. After cooling to room temperature, the mixture is ball-milled and sieved to obtain the regenerated ternary battery cathode material, realizing the green regeneration of retired ternary lithium battery cathode materials.

2. The method for recovering and regenerating retired ternary lithium battery cathode materials using a eutectic solvent according to claim 1, characterized in that, The specific process for preparing the positive electrode black powder is as follows: First, the retired ternary lithium battery is disassembled into individual battery cells. After discharge, crushing and sorting, positive electrode sheets are obtained. Then, the positive electrode sheets are cut into small square pieces, soaked in 0.5-2 mol / L NaOH solution at room temperature for 0.5-2 hours, filtered, washed and dried to obtain positive electrode material after removing aluminum impurities. Then, the positive electrode material after removing aluminum impurities is calcined in air at 500-600℃ for 3-5 hours to obtain positive electrode black powder. The ternary lithium battery refers to one or more of the following lithium batteries that use lithium nickel cobalt manganese oxide as the cathode material: NCM111, NCM523, NCM622, and NCM811.

3. The method for recovering and regenerating retired ternary lithium battery cathode materials using a eutectic solvent according to claim 1, characterized in that, The molar ratio of tetramethylammonium chloride to oxalic acid in the eutectic solvent is 2:1 to 1:4; the mass fraction of water in the DES aqueous solution is 0 to 30%.

4. The method for recovering and regenerating retired ternary lithium battery cathode materials using a eutectic solvent according to claim 1, characterized in that, The mass ratio of the DES aqueous solution to the positive electrode black powder is (30-60):

1.

5. The method for recovering and regenerating retired ternary lithium battery cathode materials using a eutectic solvent according to claim 1, characterized in that, In step S2, the amount of water added is 3 to 5 times the mass of the DES aqueous solution; in step S3, the amount of ethanol added is 8 to 10% of the amount of water added in step S2.

6. The method for recovering and regenerating retired ternary lithium battery cathode materials using a eutectic solvent according to claim 1, characterized in that, In step S4, the molar ratio of the added concentrated sulfuric acid to the lithium oxalate precipitate is 1.5 to 2.5, and the molar ratio of the added NaOH solid to the battery precursor C2 is 1.0 to 1.

1.

7. The method for recovering and regenerating retired ternary lithium battery cathode materials using a eutectic solvent according to claim 1, characterized in that, In step S5, the ball milling time is 5-10 hours; the sieve mesh size is 200-400 mesh; the calcination is performed by first heating to 450-550°C at a rate of 5°C / min, maintaining the temperature at 450-550°C for 4-6 hours, then heating to 780°C at a rate of 5°C / min, and then maintaining the temperature at 750-800°C for 8-12 hours.

8. The method for recovering and regenerating retired ternary lithium battery cathode materials using a eutectic solvent according to claim 1, characterized in that, When the DES aqueous solution is recycled 5 to 10 times, the leaching rate of Li in the retired ternary lithium battery cathode material by the eutectic solvent is not less than 95%.

9. The method for recovering and regenerating retired ternary lithium battery cathode materials using a eutectic solvent according to claim 1, characterized in that, The eutectic solvent described above achieves a leaching rate of not less than 99.5% for Ni, Co, and Mn in the cathode material of retired ternary lithium batteries.

10. The method for recovering and regenerating retired ternary lithium battery cathode materials using a eutectic solvent according to claim 1, characterized in that, The regenerated ternary battery cathode material is used to assemble ternary lithium-ion button batteries. When the electrolyte is 1 mol / L LiPF6, its initial charge capacity is not less than 180 mAh / g and its initial discharge capacity is not less than 170 mAh / g. After 50 charge-discharge cycles, its coulombic efficiency is not less than 95% and its specific capacity is not less than 145 mAh / g.

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