A method for simultaneous leaching and delithiation of lithium-ion battery cathode materials

Abstract

The present application belongs to the field of battery recycling, and particularly relates to a method for simultaneously leaching and stripping lithium ion battery positive electrode materials. Specifically, a hydrogen bond acceptor choline chloride is mixed with a hydrogen bond donor at room temperature, and stirred at 50-80 DEG C for 1-2 hours. After mixing, an intermediate mixed fluid is formed. A dissolving agent is added to the intermediate mixed fluid, and stirred at 50-80 DEG C for 2-4 hours to obtain a ternary eutectic solvent. Small positive electrode pieces are added to the ternary eutectic solvent, and heated for 70-210 minutes to obtain a leaching solution of cobalt and lithium and an aluminum foil. The aluminum foil is completely retained, and the cobalt and lithium are dissolved into the solvent. The stripping and leaching processes promote each other, effectively strengthen the leaching process, improve the leaching rate of cobalt and lithium, reduce the leaching process temperature, shorten the leaching and stripping time, and can be carried out at a larger solid-liquid ratio, thereby significantly improving the processing capacity.

Description

Technical Field

[0001] The invention belongs to the field of battery recycling and reuse, and particularly relates to a method for simultaneously leaching and stripping anode materials of lithium-ion batteries. Background Art

[0002] Currently, recycling technologies for used lithium-ion batteries include pyrometallurgical and wet recycling. Pyrometallurgical recycling involves high temperatures, consumes a lot of energy, and easily produces harmful gases. Traditional wet recycling begins by discharging and disassembling the battery to remove the positive electrode sheet. The second step is to peel the positive electrode active material from the aluminum foil. There are two main methods for peeling the positive electrode active material: one is to dissolve the binder polyvinylidene fluoride (PVDF) using organic reagents such as N-methylpyrrolidone (NMP) and N,N-dimethylformamide (DMF), and the other is to dissolve the aluminum foil using a sodium hydroxide solution. The third step is to leach the peeled active material using inorganic, alkaline, or organic acids. However, the inorganic acids and bases used in the leaching process are strong acids and bases, respectively, and these reagents pose significant risks to workers and the environment. Organic acid leaching is limited by conditions and capacity, requiring the addition of additional reducing agents to improve efficiency.

[0003] Deep eutectic solvent DES is a new type of green solvent with the advantages of simple preparation, good solubility for metal oxides, non-volatile and biodegradable. With these advantages, deep eutectic solvents can be used to recycle waste lithium-ion batteries, which can avoid harm to the environment and efficiently dissolve metals.

[0004] The publication number is CN111690813A, and the case name is a method for leaching valuable metals from waste lithium-ion batteries using a low eutectic solvent. The waste lithium-ion battery material is added to a low eutectic solvent, ultrasonically oscillated at 20-40°C, and allowed to stand; the slurry after ultrasonic treatment is filtered to separate and obtain a leachate containing valuable metals.

[0005] Publication number CN111139499A, titled "Microwave-Assisted Deep Eutectic Solvent-Based Method for Recovering Heavy Metals from Lithium-Ion Batteries," involves preparing a deep eutectic solvent; determining the melting point of the deep eutectic solvent; using microwave-assisted deep eutectic solvent to dissolve lithium-ion battery cathode materials; immersing discarded lithium-ion battery cathode materials in the deep eutectic solvent, heating and stirring in a microwave heating device until the lithium-ion battery cathode materials are completely dissolved to obtain an electrolytic mixture; electrolytically recovering heavy metals; placing the electrolytic mixture in an electrolytic cell for electrolysis; applying power for a period of time, causing heavy metal ions other than lithium ions to deposit as hydroxides on the working electrode; calcining the hydroxides to obtain metal oxides required for synthesizing lithium-ion battery cathode materials; continuing to apply power, causing lithium ions to precipitate as elemental metals on the working electrode, which are then filtered to obtain elemental lithium. Microwave-assisted enhanced leaching is then used to recover metals from the leachate by electrolytic deposition.

[0006] However, these methods often require the battery's positive electrode sheets to be peeled or crushed to obtain the positive electrode active material powder. This method is not only lengthy and complex, but also requires additional steps or solvents, increasing costs. Furthermore, these methods cannot properly recycle the aluminum foil in the positive electrode, resulting in a waste of resources.

[0007] Publication number CN111607701A, the case title is a method for recovering positive electrode metals from waste lithium-ion batteries. The positive electrode sheets are disassembled from the lithium batteries and placed in a deep eutectic solvent at a solid-to-liquid ratio of 6g / L to 8g / L. At 150°C to 300°C, the positive electrode sheets react with the deep eutectic solvent to leach the metals from the positive electrode sheets, producing a leachate and aluminum foil. The leachate is then filtered to obtain a green, transparent filtrate containing metal ions. The deep eutectic solvent is used to complete the leaching without separating the aluminum foil, and the metals can be recovered from the filtrate by electrodeposition or extraction. This method requires temperatures of 150°C to 300°C, and even after leaching for more than 24 hours, the leaching rate of cobalt and lithium still does not reach above 90%, resulting in low efficiency. Furthermore, the solid-to-liquid ratio of the positive electrode sheet to the deep eutectic solvent is only 6g / L to 8g / L. This low solid-to-liquid ratio results in reagent waste and significantly increases costs. Summary of the Invention

[0008] In order to overcome the shortcomings of the above-mentioned prior art, the object of the present invention is to provide a method for simultaneously leaching and stripping lithium-ion battery positive electrode materials. This method simplifies the recycling process, shortens the recycling time, avoids the environmental pollution problems caused by strong acids and strong bases, and can effectively leach cobalt and lithium when the solid-liquid ratio between the positive electrode sheet and the ternary deep eutectic solvent is large, thereby improving the leaching rate of cobalt and lithium, and aluminum foil can also be recycled simultaneously.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] The present invention discloses a method for simultaneously leaching and stripping a lithium ion battery positive electrode material, comprising the following steps:

[0011] The hydrogen bond acceptor choline chloride and the hydrogen bond donor are mixed at room temperature, stirred at 50°C to 80°C for 1 to 2 hours, and mixed evenly to form an intermediate mixed fluid;

[0012] adding a solvent to the intermediate mixed fluid, stirring at 50° C. to 80° C. for 2 to 4 hours to obtain a ternary deep eutectic solvent;

[0013] A small piece of positive electrode sheet is added to a ternary low eutectic solvent, the ratio of the positive electrode sheet to the low eutectic solvent is controlled within 10g / L to 40g / L, and heated for 70min to 210min to obtain a cobalt and lithium leaching solution and aluminum foil.

[0014] Furthermore, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1 to 1:3.

[0015] Furthermore, the hydrogen bond donor is any one of glycolic acid, lactic acid, malic acid, malonic acid, citric acid and gallic acid.

[0016] Furthermore, the molar ratio of the solubilizing agent to the hydrogen bond acceptor is 1:1 to 1:3.

[0017] Furthermore, the dissolving agent is any one of 2-pyrrolidone, ethylene urea, 2-aminobenzamide, aminocaprolactam, and 4-hydroxy-2-pyrrolidone.

[0018] Furthermore, the process of obtaining the small positive electrode sheet is as follows:

[0019] Soak the waste lithium-ion battery in a sodium chloride aqueous solution to discharge the lithium-ion battery, remove the outer shell and take out the positive electrode sheet, and cut the positive electrode sheet into small pieces.

[0020] Furthermore, the area of ​​the small positive electrode sheet is 1×1cm 2 ~5×5cm 2 .

[0021] Furthermore, the mass ratio of the sodium chloride aqueous solution is 20%.

[0022] Furthermore, the small cathode sheet was added to the ternary deep eutectic solvent and heated for 70 to 210 minutes to obtain the cobalt and lithium leaching solution and aluminum foil as follows:

[0023] Add a small piece of positive electrode sheet into a ternary deep eutectic solvent, heat for 10 to 30 minutes to obtain aluminum foil and active material separated from the positive electrode sheet, and remove the aluminum foil;

[0024] Continue heating for 1 to 3 hours to obtain a leaching solution of cobalt and lithium.

[0025] Furthermore, the heating temperature is controlled at 50°C to 120°C.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention discloses a method for simultaneously leaching and stripping lithium-ion battery positive electrode materials, which is as follows: a hydrogen bond acceptor choline chloride is mixed with a hydrogen bond donor at room temperature, stirred at 50°C to 80°C for 1 to 2 hours, and an intermediate mixed fluid is formed after uniform mixing. A solvent is added to the intermediate mixed fluid, and the mixture is stirred at 50°C to 80°C for 2 to 4 hours to obtain a ternary low eutectic solvent. No additional reagents or solutions are required in the experiment, thus avoiding excessive waste of reagents. A small piece of positive electrode sheet is added to the ternary low eutectic solvent, and the ratio of the positive electrode sheet to the low eutectic solvent is controlled within 10g / L to 40g / L. The mixture is heated for 70min to 210min to obtain a leaching solution of cobalt and lithium and an aluminum foil. During the process, the aluminum foil is not dissolved by the ternary low eutectic solvent and is retained intact, while the cobalt and lithium are dissolved in the solvent, thereby effectively separating them. At the same time, stripping and leaching promote each other, effectively strengthening the leaching process, increasing the leaching rate of cobalt and lithium, reducing the leaching process temperature, shortening the leaching and stripping time, and being able to operate at a larger solid-liquid ratio, significantly increasing the processing capacity. Similarly, there is no need for auxiliary strengthening measures such as ultrasound or high temperature and high pressure, simplifying the process equipment. At the same time, the operation process is carried out at a lower temperature, with low equipment requirements, significantly reducing costs, and facilitating widespread application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a flow chart of the present invention;

[0029] Figure 2 is a process flow chart of the present invention;

[0030] Figure 3 The molecular formulas of the hydrogen bond acceptor and hydrogen bond donor used as raw materials in the present invention are:

[0031] Figure 4 is the positive electrode sheet before leaching;

[0032] Figure 5 It is the positive electrode in the leaching process;

[0033] Figure 6 It is the silver-white aluminum foil after the positive electrode is leached;

[0034] Figure 7 This is a graph showing the leaching rates of lithium and cobalt in Example 4 of the present invention. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0037] The present invention is described in further detail below with reference to the accompanying drawings:

[0038] See also Figure 1 The present invention discloses a method for simultaneously leaching and stripping a positive electrode material of a lithium-ion battery, comprising the following steps:

[0039] S1. Mix the hydrogen bond acceptor choline chloride and the hydrogen bond donor at room temperature, stir at 50℃~80℃ for 1~2 hours, and mix them evenly to form an intermediate mixed fluid. Figure 3 The molecular formulas of the hydrogen bond acceptor and hydrogen bond donor used as raw materials in the present invention are:

[0040] The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1 to 1:3.

[0041] The hydrogen bond donor is any one of glycolic acid, lactic acid, malic acid, malonic acid, citric acid and gallic acid.

[0042] S2. Add a solvent to the intermediate mixed fluid and stir at 50°C to 80°C for 2 to 4 hours to obtain a ternary deep eutectic solvent;

[0043] The molar ratio of the solubilizing agent to the hydrogen bond acceptor is 1:1 to 1:3.

[0044] The dissolving agent is any one of 2-pyrrolidone, ethylene urea, 2-aminobenzamide, aminocaprolactam, and 4-hydroxy-2-pyrrolidone.

[0045] S3. Add a small piece of cathode sheet to the ternary deep eutectic solvent, control the ratio of cathode sheet to deep eutectic solvent within 10g / L~40g / L, and heat for 70min~210min to obtain the leaching solution of cobalt and lithium and aluminum foil, see Figure 4 is the positive electrode before leaching, Figure 5 is the positive electrode in the leaching process, Figure 6 It is the silver-white aluminum foil after the positive electrode is leached.

[0046] The process of obtaining a small positive electrode sheet is as follows:

[0047] Soak the waste lithium-ion battery in a sodium chloride aqueous solution to discharge the lithium-ion battery, remove the outer shell and take out the positive electrode sheet, and cut the positive electrode sheet into small pieces.

[0048] The area of ​​the small positive electrode sheet is 1×1cm 2 ~5×5cm 2 .

[0049] The mass ratio of the sodium chloride aqueous solution is 10% to 25%.

[0050] A small piece of positive electrode is added to a ternary deep eutectic solvent and heated for 70 to 210 minutes to obtain a cobalt and lithium leaching solution and aluminum foil as follows:

[0051] Add a small piece of positive electrode sheet into a ternary deep eutectic solvent, heat for 10 to 30 minutes to obtain aluminum foil and active material separated from the positive electrode sheet, and remove the aluminum foil;

[0052] Continue heating for 1 to 3 hours to obtain a leaching solution of cobalt and lithium.

[0053] The heating temperature is controlled at 50℃~120℃.

[0054] See also Figure 1In another feasible embodiment of the present invention, the following is adaptively modified according to the circumstances. The hydrogen bond acceptor choline chloride is mixed with the hydrogen bond donor at room temperature, stirred at 50°C to 80°C for 1 to 2 hours, and mixed evenly to form an intermediate mixed fluid. A solvent is added to the intermediate mixed fluid, and stirred at 50°C to 80°C for 2 to 4 hours to obtain a ternary low eutectic solvent. No additional reagents or solutions are required in the experiment, avoiding excessive waste of reagents. A small piece of positive electrode sheet is added to the ternary low eutectic solvent, and the ratio of the positive electrode sheet to the low eutectic solvent is controlled within 10g / L to 40g / L, and heated for 70min to 210min to obtain a leaching solution of cobalt and lithium and an aluminum foil. During the process, the aluminum foil will not be dissolved by the ternary low eutectic solvent and will be retained intact, while the cobalt and lithium will be dissolved in the solvent, so that they are effectively separated. At the same time, stripping and leaching promote each other, effectively strengthening the leaching process, increasing the leaching rate of cobalt and lithium, reducing the temperature, shortening the leaching and stripping time, and being able to operate at a larger solid-liquid ratio, significantly increasing the processing capacity. No other additives or reducing agents are required during the operation, avoiding excessive waste of reagents. Similarly, there is no need for auxiliary strengthening measures such as ultrasound or high temperature and high pressure, simplifying the process equipment. At the same time, the operation process is carried out at a lower temperature, with low equipment requirements, significantly reducing costs, and facilitating widespread application. Figure 2 is a process flow chart of the present invention, Figure 7 The figure shows the leaching rate results of lithium and cobalt of the present invention. The present invention avoids the cumbersome steps and redundant reagents of the traditional recovery process, and can completely recycle the aluminum foil, and the leaching rate of cobalt and lithium is relatively fast. The method of the present invention simplifies the recovery process, shortens the recovery time, avoids the environmental pollution problems caused by strong acids and strong bases, and can effectively leach cobalt and lithium when the solid-liquid ratio between the positive electrode sheet and the ternary low eutectic solvent is large, thereby improving the leaching rate of cobalt and lithium, and the aluminum foil can also be recovered at the same time. It solves the problems of multiple steps in the recovery process, high cost, low efficiency and serious pollution.

[0055] Example 1:

[0056] Choline chloride and glycolic acid were mixed in a molar ratio of 1:1, heated in an oil bath on a magnetic heating stirrer at 50°C, and stirred at a stirring speed of 650 r / min for 1 hour to obtain an intermediate mixed fluid;

[0057] 2-Pyrrolidone was added to the intermediate mixed fluid at a ratio of 1:1. Heating and stirring were continued for 2 hours under the above conditions, followed by cooling to room temperature to obtain a ternary deep eutectic solvent of choline chloride / glycolic acid / 2-pyrrolidone.

[0058] Discharge the used lithium-ion battery, remove the outer shell and take out the positive electrode sheet, and cut the positive electrode sheet into 1×1cm 2small pieces;

[0059] The sheared cathode sheet was added to a ternary deep eutectic solvent of choline chloride / hydroxyacetic acid / 2-pyrrolidone at a solid-to-liquid ratio of 10 g / L. The sheet was heated in an oil bath at 50°C and stirred for 10 minutes before the aluminum foil was removed. The calculated cathode material stripping rate was 78.9%. The stripped cathode material was heated for another hour, allowed to stand, and filtered to obtain a filtrate. The Co and Li contents in the filtrate were analyzed using ICP-OES. Testing and calculations showed that the leaching rates of Co and Li in the ternary deep eutectic solvent were 69.2% and 73.5%, respectively.

[0060] Example 2:

[0061] Choline chloride and lactic acid were mixed in a molar ratio of 1:2, heated in an oil bath on a magnetic heating stirrer at 65°C, and stirred at a stirring speed of 650 r / min for 2 hours to obtain an intermediate mixed fluid;

[0062] Ethylene urea was added to the intermediate mixed fluid at a ratio of 1:2. Heating and stirring were continued under the above conditions for 2 hours, followed by cooling to room temperature to obtain a ternary deep eutectic solvent of choline chloride / lactic acid / ethylene urea.

[0063] Discharge the used lithium-ion battery, remove the outer shell and take out the positive electrode sheet, and cut the positive electrode sheet into 1×1cm 2 small pieces;

[0064] The sheared cathode sheet was added to a ternary deep eutectic solvent of choline chloride / lactic acid / ethylene urea at a solid-to-liquid ratio of 25 g / L. The sheet was heated in an oil bath at 70°C and stirred for 20 minutes. After the aluminum foil was removed, the stripped cathode material yield was calculated to be 87.0%. The stripped cathode material was heated for another 2 hours, allowed to stand, and filtered to obtain the filtrate. The Co and Li contents in the filtrate were analyzed by ICP-OES. Testing and calculation revealed that the leaching yields of Co and Li in the ternary deep eutectic solvent were 83.3% and 89.5%, respectively.

[0065] Example 3:

[0066] Choline chloride and malic acid were mixed in a molar ratio of 1:2, heated in an oil bath on a magnetic heating stirrer at 65°C, and stirred at a stirring speed of 650 r / min for 1 hour to obtain an intermediate mixed fluid;

[0067] 2-Aminobenzamide was added to the intermediate mixed fluid at a ratio of 1:1. Heating and stirring were continued for 3 hours under the above conditions, followed by cooling to room temperature to obtain a ternary deep eutectic solvent of choline chloride / malic acid / 2-aminobenzamide.

[0068] Discharge the used lithium-ion battery, remove the outer shell and take out the positive electrode sheet, and cut the positive electrode sheet into 3×3cm 2 Small piece of.

[0069] The sheared cathode sheet was added to a ternary deep eutectic solvent of choline chloride / malic acid / 2-aminobenzamide at a solid-to-liquid ratio of 25 g / L. The sheet was heated in an oil bath at 90°C and stirred for 20 minutes before the aluminum foil was removed. The calculated cathode material stripping efficiency was 93.8%. The stripped cathode material was heated for another 2 hours, allowed to stand, and filtered to obtain a filtrate. The Co and Li contents in the filtrate were analyzed using ICP-OES. Testing and calculations showed that the leaching efficiency of Co and Li in the ternary deep eutectic solvent was 91.3% and 93.5%, respectively.

[0070] Example 4:

[0071] Choline chloride and malonic acid were mixed in a molar ratio of 1:2, and heated in an oil bath on a magnetic heating stirrer at a heating temperature of 80° C. The mixed liquid was stirred at a stirring speed of 650 r / min for 1 hour to obtain an intermediate mixed fluid.

[0072] 2-Pyrrolidone was added to the intermediate mixed fluid at a ratio of 2-Pyrrolidone to choline chloride of 1:1. After continuing heating and stirring under the above conditions for 4 hours, the mixture was cooled to room temperature to obtain a ternary deep eutectic solvent of choline chloride / malonic acid / 2-Pyrrolidone.

[0073] Discharge the used lithium-ion battery, remove the outer shell and take out the positive electrode sheet, and cut the positive electrode sheet into 1×1cm 2 Small piece of.

[0074] The sheared cathode sheet was added to a ternary deep eutectic solvent of choline chloride / malonic acid / 2-pyrrolidone at a solid-to-liquid ratio of 10 g / L. The sheet was heated in an oil bath at 120°C and stirred for 30 minutes before the aluminum foil was removed. The calculated cathode material stripping rate was 99.8%. The stripped cathode material was heated for another 3 hours, allowed to stand, and filtered to obtain a filtrate. The Co and Li contents in the leached solution were analyzed using ICP-OES. Testing and calculations showed that the leaching rates of Co and Li in the ternary deep eutectic solvent were 98.2% and 99.3%, respectively.

[0075] Embodiment 5:

[0076] Choline chloride and citric acid were mixed in a molar ratio of 1:2, and heated in an oil bath on a magnetic heating stirrer at a heating temperature of 80° C. The mixed liquid was stirred at a stirring speed of 650 r / min for 1 hour to obtain an intermediate mixed fluid.

[0077] Aminocaprolactam was added to the intermediate mixed fluid in a ratio of 1:3. After heating and stirring for 4 hours under the above conditions, the mixture was cooled to room temperature to obtain a ternary deep eutectic solvent of choline chloride / citric acid / aminocaprolactam.

[0078] Discharge the used lithium-ion battery, remove the outer shell and take out the positive electrode sheet, and cut the positive electrode sheet into 3×3cm 2 Small piece of.

[0079] The sheared cathode sheet was added to a ternary deep eutectic solvent of choline chloride / citric acid / aminocaprolactam at a solid-to-liquid ratio of 40 g / L. The material was heated in an oil bath at 90°C and stirred for 30 minutes. After removal of the aluminum foil, the stripped cathode material was calculated to have a 90.4% stripping rate. The stripped cathode material was heated for another 3 hours, allowed to stand, and filtered to obtain the filtrate. The Co and Li contents in the filtrate were analyzed by ICP-OES. Testing and calculation revealed that the leaching rates of Co and Li in the ternary deep eutectic solvent were 91.0% and 92.7%, respectively.

[0080] Example 6:

[0081] Choline chloride and gallic acid were mixed in a molar ratio of 1:3, and heated in an oil bath on a magnetic heating stirrer at a heating temperature of 50° C. The mixed liquid was stirred at a stirring speed of 650 r / min for 2 hours to obtain an intermediate mixed fluid.

[0082] The intermediate mixed fluid was added with 4-hydroxy-2-pyrrolidinone, and the ratio of 4-hydroxy-2-pyrrolidinone to choline chloride was 1:1. After the above conditions were continued to be heated and stirred for 2 hours, cooling to room temperature, the choline chloride / gallic acid / 4-hydroxy-2-pyrrolidinone ternary eutectic solvent was obtained.

[0083] The spent lithium ion battery was discharged, and the positive plate was taken out after removing the shell. The positive plate was cut into 5x5 cm 2 small pieces.

[0084] The cut positive plate was added to the choline chloride / gallic acid / 4-hydroxy-2-pyrrolidinone ternary eutectic solvent, and the solid-liquid ratio of the positive plate to the choline chloride / gallic acid / 4-hydroxy-2-pyrrolidinone ternary eutectic solvent was 40 g / L. After oil bath heating and stirring at 120°C for 30 min, the aluminum foil was taken out, and the positive material stripping rate was calculated to be 80.6%. The stripped positive material was continuously heated for 3h, and the filtrate was obtained by standing and filtering. The Co and Li contents in the leaching solution were analyzed by ICP-OES. After detection and calculation, the leaching rates of Co and Li in the choline chloride / citric acid / amino caprolactam ternary eutectic solvent were 81.4% and 83.1%, respectively.

[0085] Example Seven:

[0086] Choline chloride and malic acid were mixed in a molar ratio of 1:2, and oil bath heating was performed on a magnetic heating stirrer. The heating temperature was 80°C, the stirring speed was 650 r / min, and the stirring time was 1 hour, and the intermediate mixed fluid was obtained;

[0087] 2-pyrrolidinone was added to the intermediate mixed fluid, and the ratio of 2-pyrrolidinone to choline chloride was 1:2. After the above conditions were continued to be heated and stirred for 1 hour, cooling to room temperature, the choline chloride / malic acid / 2-pyrrolidinone ternary eutectic solvent was obtained.

[0088] The spent lithium ion battery was discharged, and the positive plate was taken out after removing the shell. The positive plate was cut into 5x5 cm 2 small pieces.

[0089] The sheared cathode sheet was added to a ternary deep eutectic solvent of choline chloride / malic acid / 2-pyrrolidone at a solid-to-liquid ratio of 25 g / L. The sheet was heated in an oil bath at 120°C and stirred for 30 minutes before the aluminum foil was removed. The calculated cathode material stripping efficiency was 98.7%. The stripped cathode material was heated for another 3 hours, allowed to stand, and filtered to obtain a filtrate. The Co and Li contents in the filtrate were analyzed using ICP-OES. Testing and calculations showed that the leaching efficiency of Co and Li in the ternary deep eutectic solvent was 94.4% and 83.1%, respectively.

[0090] Embodiment 8:

[0091] Choline chloride and glycolic acid were mixed in a molar ratio of 1:2, heated in an oil bath on a magnetic heating stirrer at 70°C, and stirred at a stirring speed of 650 r / min for 2 hours to obtain an intermediate mixed fluid;

[0092] Add 2-pyrrolidone to the intermediate mixed fluid at a ratio of 1:2. Continue heating and stirring under the above conditions for 2 hours, then cool to room temperature to obtain a ternary deep eutectic solvent of choline chloride / glycolic acid / 2-pyrrolidone.

[0093] Discharge the used lithium-ion battery, remove the outer shell and take out the positive electrode sheet, and cut the positive electrode sheet into 5×5cm 2 small pieces;

[0094] The sheared cathode sheet was added to a ternary deep eutectic solvent of choline chloride / hydroxyacetic acid / 2-pyrrolidone at a solid-to-liquid ratio of 40 g / L. The sheet was heated in an oil bath at 120°C and stirred for 30 minutes before the aluminum foil was removed. The calculated cathode material stripping rate was 99.1%. The stripped cathode material was heated for another 3 hours, allowed to stand, and filtered to obtain a filtrate. The Co and Li contents in the filtrate were analyzed using ICP-OES. Testing and calculations showed that the leaching rates of Co and Li in the ternary deep eutectic solvent were 92.9% and 94.5%, respectively.

[0095] See also Figure 7The figure shows the leaching rate results of lithium and cobalt of the present invention. The present invention utilizes a ternary low eutectic solvent to simultaneously and effectively strip and leach the positive electrode material of a lithium-ion battery. The aluminum foil will not be dissolved by the low eutectic solvent and will be completely retained, while the cobalt and lithium will be dissolved in the solvent, allowing them to be effectively separated. At the same time, stripping and leaching promote each other, effectively strengthening the leaching process, reducing the temperature, shortening the leaching and stripping time, and can be carried out at a larger solid-liquid ratio, significantly increasing the processing capacity. No other additives or reducing agents are required during the operation, avoiding excessive waste of reagents. Similarly, there is no need to use auxiliary strengthening measures such as ultrasound or high temperature and high pressure, simplifying the process equipment. At the same time, the equipment requirements are low at a lower temperature, significantly reducing costs and facilitating promotion and application. The present invention avoids the cumbersome steps and redundant reagents of the traditional recovery process, and can completely recycle the aluminum foil, achieving a fast and efficient level of leaching of cobalt and lithium. It alleviates the problems of multiple steps, high cost, low efficiency and serious pollution in the recovery process.

[0096] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for simultaneously leaching and stripping a positive electrode material for a lithium-ion battery, characterized in that: The steps include: The hydrogen bond acceptor choline chloride and the hydrogen bond donor are mixed at room temperature, stirred at 50°C to 80°C for 1 to 2 hours, and mixed evenly to form an intermediate mixed fluid; adding a solvent to the intermediate mixed fluid, stirring at 50° C. to 80° C. for 2 to 4 hours to obtain a ternary deep eutectic solvent; The molar ratio of the solubilizing agent to the hydrogen bond acceptor is 1:1 to 1:3; The dissolving agent is any one of 2-pyrrolidone, ethylene urea, 2-aminobenzamide, aminocaprolactam, and 4-hydroxy-2-pyrrolidone; A small piece of positive electrode sheet is added to a ternary low eutectic solvent, the ratio of the positive electrode sheet to the low eutectic solvent is controlled within 10g / L to 40g / L, and heated for 70min to 210min to obtain a cobalt and lithium leaching solution and aluminum foil.

2. The method for simultaneously leaching and stripping a positive electrode material for a lithium-ion battery according to claim 1, wherein: The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1 to 1:

3.

3. The method for simultaneously leaching and stripping a positive electrode material for a lithium-ion battery according to claim 2, wherein: The hydrogen bond donor is any one of glycolic acid, lactic acid, malic acid, malonic acid, citric acid and gallic acid.

4. The method for simultaneously leaching and stripping a positive electrode material for a lithium-ion battery according to claim 1, wherein: The process of obtaining the small positive electrode sheet is as follows: Soak the waste lithium-ion battery in a sodium chloride aqueous solution to discharge the lithium-ion battery, remove the outer shell and take out the positive electrode sheet, and cut the positive electrode sheet into small pieces.

5. The method for simultaneously leaching and stripping a positive electrode material for a lithium-ion battery according to claim 4, characterized in that: The area of ​​the small positive electrode sheet is 1×1 cm 2 ~5×5cm 2 .

6. The method for simultaneously leaching and stripping a positive electrode material for a lithium-ion battery according to claim 4, characterized in that: The mass ratio of the sodium chloride aqueous solution is 20%.

7. The method for simultaneously leaching and stripping a lithium-ion battery cathode material according to claim 1, wherein: The small piece of positive electrode is added to the ternary deep eutectic solvent and heated for 70 minutes to 210 minutes to obtain the cobalt and lithium leaching solution and aluminum foil as follows: Add a small piece of positive electrode sheet into a ternary deep eutectic solvent, heat for 10 to 30 minutes to obtain aluminum foil and active material separated from the positive electrode sheet, and remove the aluminum foil; Continue heating for 1 to 3 hours to obtain a leaching solution of cobalt and lithium.

8. The method for simultaneously leaching and stripping a lithium-ion battery cathode material according to claim 7, wherein: The heating temperature is controlled at 50℃~120℃.

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