Eutectic solvent, preparation thereof and application thereof in recycling of waste ternary lithium battery cathode material

Abstract

The application discloses a eutectic solvent, preparation thereof and application thereof in recycling of positive electrode materials of waste ternary lithium batteries. The eutectic solvent is composed of ethylene glycol and lactic acid, wherein the molar ratio of ethylene glycol and lactic acid is 1:10-10:1. A new eutectic solvent system is creatively constructed, selective leaching of lithium element in the positive electrode materials of waste ternary lithium batteries is realized, and the co-precipitation process of nickel, cobalt, manganese and other key metal precursors is simultaneously promoted, the high-value recycling and utilization of waste ternary lithium batteries are promoted, the complex process of traditional multi-metal step-by-step separation is avoided, and the operation steps are simplified. In addition, the eutectic solvent can be recycled for more than 5 times, and the battery recycling cost is reduced. The recycling method provided by the application also greatly widens the separation and recycling way of valuable metals in waste batteries, and shows wide application potential and important value in the field of resource recycling.

Description

Technical Field

[0001] This invention relates to the field of recycling waste lithium-ion battery materials. More specifically, it relates to eutectic solvents, their preparation, and their application in recycling waste ternary lithium battery cathode materials. Background Technology

[0002] Lithium-ion batteries (LIBs), with their superior electrochemical performance, have become core components in the energy storage field. This is particularly evident in the new energy vehicle industry, where, as the primary power source, the electrode material structure inevitably suffers damage after prolonged use, leading to performance degradation and eventual retirement. Therefore, recycling and reusing spent LIBs can not only effectively prevent environmental pollution but also address the challenge of domestic battery resource shortages, alleviate production capacity pressures in the battery manufacturing sector, and promote the sustainable development of a circular economy.

[0003] Current waste battery recycling processes primarily rely on hydrometallurgical technology. The core of this technology lies in using acidic or alkaline solutions to convert solid metals in electrode materials into a liquid state, followed by complex processes such as solvent extraction, chemical precipitation, adsorption separation, and electrochemical treatment to extract metal ions from the solution. However, current technologies mainly focus on the simultaneous separation of elements from the cathode material. While this can recover individual metal products for application in their respective fields, the process is cumbersome and prone to cross-contamination and loss of metal elements. Furthermore, existing recycling processes commonly use strong inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid as leaching agents, supplemented by reducing agents such as hydrogen peroxide and sodium hyposulfite to enhance leaching efficiency. This process inevitably generates large amounts of acid mist, causing severe corrosion to recycling equipment and plant structures, and seriously threatening the health and safety of frontline operators. Given these challenges, to promote the development of waste battery recycling towards a more environmentally friendly and economical direction, it is urgent to explore and apply new green solvents. These solvents should possess the characteristics of high efficiency, low toxicity, and recyclability, thereby achieving efficient recovery and reuse of metal elements.

[0004] In recent years, eutectic solvents (DESs), as an emerging "green solvent," have begun to gain prominence in the battery recycling field due to their significant advantages—inexpensive and readily available raw materials, simple preparation processes, stable physicochemical properties, good conductivity, and biodegradability. Particularly noteworthy is their excellent solubility for various metal oxides, making them a promising alternative to inorganic and organic acids as battery recycling leaching agents. Although current DES systems have made some progress in the recovery of metal elements from spent lithium cobalt oxide batteries, existing systems primarily focus on this type of battery, with limited reports on their application to other lithium batteries. Furthermore, they suffer from drawbacks such as low reaction kinetic efficiency and the need for high reaction temperatures. In contrast, research on the recycling of ternary lithium batteries is still insufficient. Research focuses primarily on the simultaneous separation of metal elements, emphasizing high leaching rates. However, if secondary recycling is considered, it requires the addition of precipitants to separate the metals from the leachate one by one, a lengthy process with low selectivity and resulting in metal loss. In view of this, we explore and synthesize novel eutectic solvent systems with the aim of achieving breakthroughs: on the one hand, to achieve efficient and selective extraction of lithium, thereby improving the precision and efficiency of resource recovery; on the other hand, to promote the co-precipitation of elements such as nickel, cobalt, and manganese, laying a solid foundation for subsequent recycling. Summary of the Invention

[0005] Based on the above-mentioned shortcomings, the first objective of this invention is to provide a eutectic solvent. This invention focuses on constructing an innovative eutectic solvent system for the treatment of spent lithium batteries. This system can efficiently achieve selective leaching of lithium and simultaneously promote the co-precipitation process of key metal precursors such as nickel, cobalt, and manganese. This makes the entire recycling process compact and efficient, eliminating the need to add precipitants from the metal leachate for the separation of nickel, cobalt, and manganese. It possesses high flexibility and adjustability, greatly expanding the pathways for the separation and recycling of valuable metals from spent lithium batteries, demonstrating broad application potential and significant value in the field of resource recycling.

[0006] A second objective of this invention is to provide a method for preparing the eutectic solvent as described above.

[0007] The third objective of this invention is to utilize the eutectic solvent described above in the recycling of waste ternary lithium battery cathode materials.

[0008] The fourth objective of this invention is to provide a method for recycling and utilizing cathode materials from waste ternary lithium batteries.

[0009] To achieve the first objective mentioned above, the present invention adopts the following technical solution:

[0010] This invention discloses a eutectic solvent composed of ethylene glycol and lactic acid, wherein the molar ratio of ethylene glycol to lactic acid is 1:10-10:1; exemplaryly, the molar ratio of ethylene glycol to lactic acid can be 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc., or any range formed by any two values.

[0011] Furthermore, when the molar ratio of ethylene glycol to lactic acid is 1:2-2:1, the selective leaching of lithium and the simultaneous co-precipitation of nickel, cobalt, and manganese are most effective.

[0012] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0013] This invention discloses a method for preparing the eutectic solvent as described above, comprising the following steps:

[0014] Ethylene glycol and lactic acid are mixed in a certain proportion and heated and stirred at 50-120°C for 20-120 minutes to obtain a uniform and transparent liquid, which is the eutectic solvent.

[0015] To achieve the third objective mentioned above, the present invention adopts the following technical solution:

[0016] This invention discloses an application of the eutectic solvent described above in the recycling of waste ternary lithium battery cathode materials.

[0017] To achieve the fourth objective mentioned above, the present invention adopts the following technical solution:

[0018] This invention discloses a method for recycling waste ternary lithium battery cathode materials. The method uses a eutectic solvent as described above to selectively leach lithium from the waste ternary lithium battery cathode materials to obtain a lithium-rich solution, and simultaneously leach nickel, cobalt, and manganese from the waste ternary lithium battery cathode materials to directly obtain nickel-cobalt-manganese coprecipitates.

[0019] This recycling method achieves a compact and efficient design of the entire recycling process by selecting a suitable eutectic solvent system (ethylene glycol + lactic acid). Under the influence of the eutectic solvent, valuable metals (lithium, nickel, cobalt, and manganese) in the cathode material of ternary lithium batteries can be efficiently leached, improving the efficiency of metal recovery. More importantly, under the influence of the eutectic solvent, the leached lithium can be directly dispersed in the eutectic solvent, while nickel, cobalt, and manganese can be directly and simultaneously converted into nickel-cobalt-manganese co-precipitates without the addition of external precipitants. This allows nickel, cobalt, and manganese to be selectively separated from lithium naturally. This recycling method saves the stepwise precipitation and recovery process of nickel, cobalt, and manganese, and has high flexibility and adjustability.

[0020] Furthermore, the recycling method also includes the following steps:

[0021] After solid-liquid separation of lithium-rich solution and nickel-cobalt-manganese coprecipitate, a precipitant is added to the lithium-rich solution to obtain lithium-rich precipitate, and the nickel-cobalt-manganese coprecipitate is calcined to obtain nickel-cobalt-manganese cathode intermediate oxide.

[0022] Lithium-rich precipitate and nickel-cobalt-manganese cathode intermediate oxide are mixed and calcined to obtain regenerated cathode powder;

[0023] Regenerated ternary lithium batteries were prepared using the obtained recycled cathode powder.

[0024] Furthermore, the recycling method specifically includes the following steps:

[0025] Waste ternary lithium battery cathode materials are heat-treated to obtain positive electrode active materials. The heat treatment process involves treating the waste ternary lithium battery cathode materials at 500-600℃ for 0.5-1.5 hours to remove conductive agents and binders from the cathode materials. The waste ternary lithium battery cathode materials include LiNi. 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2 and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 One or more of O2.

[0026] The positive electrode active material is added to a eutectic solvent and stirred and leached at 60-120℃ for 30-720 min. During the leaching process, metallic lithium will leach into the eutectic solvent, and nickel, cobalt and manganese precipitates will be continuously generated. After vacuum filtration, nickel, cobalt and manganese coprecipitates and lithium-rich solutions are obtained.

[0027] The nickel-cobalt-manganese coprecipitate was washed with anhydrous ethanol, dried at 50-80℃, and then calcined in a muffle furnace to obtain nickel-cobalt-manganese cathode intermediate oxide. The calcination temperature was 400-800℃ and the calcination time was 1-6h.

[0028] After the lithium-rich solution is evaporated and concentrated, a precipitant (such as sodium carbonate) is added to precipitate the lithium ions free in the solvent, thus obtaining a lithium-rich precipitate. In this process, the reaction temperature is 80-100℃ and the reaction time is 60-120min.

[0029] To ultimately recover reusable cathode powder, it is necessary to mix nickel-cobalt-manganese cathode intermediate oxides and lithium-rich precipitates, and then calcine them at high temperatures. High-temperature calcine generally consists of two steps: the first step is calcine at 450-600℃ for 3-6 hours, which is a pre-calcine process; the second step is calcine at an even higher temperature of 800-950℃ for 8-12 hours to obtain regenerated cathode powder.

[0030] Furthermore, the solid-liquid ratio of the positive electrode active material and the eutectic solvent is 10-100 g / L. For example, the solid-liquid ratio of the positive electrode active material to the eutectic solvent can be 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, etc., or any range formed by two points.

[0031] Furthermore, the leaching temperature is 80-120℃, and the leaching time is 60-240 minutes. If the leaching temperature is too low or the leaching time is too short, it will affect the leaching efficiency of lithium and the precipitation effect of nickel, cobalt, and manganese, and there may even be a phenomenon where nickel, cobalt, and manganese cannot be co-precipitated.

[0032] Furthermore, the stirring speed is controlled at 200-1000 rpm during the leaching process.

[0033] Furthermore, the nickel-cobalt-manganese cathode intermediate oxide and lithium-rich precipitate can be mixed by ball milling. High-speed stirred mills, ball mills, tube mills, cone mills, rod mills, or sand mills can be used during the ball milling process.

[0034] The beneficial effects of this invention are as follows:

[0035] This invention provides a eutectic solvent, its preparation, and its application in recycling waste ternary lithium battery cathode materials. Compared with existing technologies, it has the following advantages:

[0036] 1. High-efficiency separation and direct recovery: This invention first utilizes a novel eutectic solvent system (ethylene glycol + lactic acid) to leach waste ternary lithium battery cathode materials. By controlling the amounts of ethylene glycol and lactic acid, as well as the leaching temperature and time, highly efficient leaching and separation of nickel, cobalt, and manganese with lithium elements are achieved. This allows nickel, cobalt, and manganese to precipitate naturally without the introduction of additional precipitants, effectively separating them from the lithium-rich solution. This process not only simplifies the recovery process but also allows nickel, cobalt, and manganese to be directly recovered as cathode precursor precipitates, greatly improving recovery efficiency and purity, and shortening the processing cycle. The entire process design is both simple and efficient, promoting resource recycling and significantly enhancing social and economic benefits, achieving a win-win situation of environmental friendliness and economic benefits.

[0037] 2. Wide Applicability and Breakthrough: This method has strong universality and can be applied to the separation of lithium and nickel-cobalt-manganese in various types of ternary lithium batteries, such as LiNi. 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2 and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and other technologies have broken the limitations of traditional eutectic solvent technology, which is limited to the recycling of lithium cobalt oxide batteries or the stepwise recycling of single elements, and have opened up new avenues for the comprehensive and meaningful regeneration of waste batteries.

[0038] 3. Dual Environmental and Economic Benefits: The eutectic solvent used in this invention is environmentally friendly, low-polluting, and relatively inexpensive, helping to reduce overall recycling costs. Furthermore, the leaching separation effect remains essentially unchanged after being reused more than five times, demonstrating high recyclability. In addition, the recycled cathode powder produced by this invention is not only valuable but also exhibits strong adjustability in its recycling process. Lithium batteries prepared using the recycled cathode powder maintain excellent electrochemical performance, fully validating the feasibility and value of this recycling technology. Attached Figure Description

[0039] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0040] Figure 1 The diagram shows the process flow chart for recycling and utilizing the cathode material of waste ternary lithium batteries according to the present invention.

[0041] Figure 2 The XRD pattern of lithium carbonate prepared in Example 1 of the present invention is shown.

[0042] Figure 3 The XRD patterns of the nickel-cobalt-manganese coprecipitate product (a), the nickel-cobalt-manganese intermediate oxide (b), and the cathode powder (c) prepared in Example 1 of the present invention are shown.

[0043] Figure 4 The SEM images show the nickel-cobalt-manganese coprecipitate product (a), nickel-cobalt-manganese intermediate oxide (b), and cathode powder (c) prepared in Example 1 of the present invention.

[0044] Figure 5 The electrochemical performance diagram of the regenerated battery in Example 1 of the present invention is shown.

[0045] Figure 6 The diagram shows the leaching efficiency of the leaching agent in Example 1 of the present invention after 5 cycles. Detailed Implementation

[0046] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0047] This invention provides a process for regenerating spent ternary lithium-ion battery cathode materials using a low-cost, environmentally friendly eutectic solvent system. This method represents a novel approach to battery cathode recycling. The method involves leaching pretreated cathode material powder in a green, non-aqueous system—a eutectic solvent (ethylene glycol + lactic acid). After the reaction, lithium is selectively leached from the spent cathode material, and a battery-grade lithium-rich precipitate is obtained using a precipitant (e.g., sodium carbonate). Nickel, cobalt, and manganese are directly leached and then co-precipitated in the eutectic solvent system to form cathode precursors. Further, these precursors are calcined at high temperatures to obtain cathode intermediate oxides. Finally, the prepared lithium-rich precipitate and cathode intermediate oxides are mixed and calcined at high temperatures to obtain regenerated cathode powder. Lithium-ion batteries assembled from the regenerated cathode powder exhibit excellent electrochemical performance, fully validating the feasibility and value of this recycling technology. Furthermore, this method features a short process, high-value recycled products, strong adjustability, and is environmentally friendly, making it valuable for separating and recycling valuable metals from batteries.

[0048] The following describes in detail the method for recycling waste ternary lithium battery cathode materials using a eutectic solvent system, including the following steps:

[0049] (1) Pretreatment of cathode materials from waste ternary lithium batteries

[0050] Waste ternary lithium-ion cathode sheets are heat-treated at 500-600℃ for 0.5-1.5 hours to remove conductive agents and binders. After peeling off the aluminum sheet, the positive electrode active material is obtained. The waste ternary lithium battery cathode material includes LiNi. 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2 and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3One or more of O2.

[0051] (2) Preparation of eutectic solvent

[0052] Ethylene glycol and lactic acid are mixed in proportion and heated and stirred at 50-120℃ for 20-120 minutes to obtain a uniform and transparent liquid.

[0053] (3) Selective leaching and co-precipitation of metals in cathode materials

[0054] The positive electrode active material obtained in step 1 is added to the eutectic solvent obtained in step 2, and the solid-liquid ratio is controlled at 10-100 g / L. The mixture is stirred and leached at 60-120℃ for 30-720 min. After vacuum filtration, nickel-cobalt-manganese coprecipitate and lithium-rich solution are obtained. The nickel-cobalt-manganese coprecipitate is washed with anhydrous ethanol and dried at 50-80℃.

[0055] (4) High-temperature calcination of nickel-cobalt-manganese precipitate

[0056] The nickel-cobalt-manganese coprecipitate obtained in step 3 was calcined in a muffle furnace at 400-800℃ for 1-6 hours to obtain nickel-cobalt-manganese cathode intermediate oxide.

[0057] (5) Preparation of lithium carbonate by precipitation of lithium-rich solution

[0058] The lithium-rich solution obtained in step 3 is evaporated and concentrated, and then a sodium carbonate solution is added to precipitate lithium carbonate. The reaction equation is Li + +CO3 2- →Li2CO3↓, the precipitate is then washed with anhydrous ethanol and dried to obtain lithium carbonate product.

[0059] (6) Preparation of battery positive electrode powder

[0060] The nickel-cobalt-manganese cathode intermediate oxide obtained in step 4 and the lithium carbonate obtained in step 5 are mixed and calcined in a muffle furnace at high temperature in two steps to obtain regenerated cathode powder. The calcination temperature of the first step is 450-600℃ and the calcination time is 3-6h. The calcination temperature of the second step is 800-950℃ and the calcination time is 8-12h.

[0061] (7) Assembly and electrochemical performance testing of regenerated batteries

[0062] A button cell was assembled in the following order: negative electrode shell - spring sheet - gasket - lithium sheet - electrolyte - separator - electrolyte - positive electrode sheet made of the above positive electrode powder - gasket - positive electrode shell, and its electrochemical performance was tested.

[0063] The positive electrode sheet is prepared by mixing the positive electrode powder prepared in step 6 with a mass ratio of positive electrode powder: conductive agent: binder of 80:10:10 until the slurry is viscous. Then, it is coated onto aluminum foil by the "blade method" and cut into positive electrode sheets.

[0064] Optionally, the electrolyte solute is one or more of lithium hexafluorophosphate (LiPF6) and lithium tetrafluoroborate (LiBF4), and the solvent is one or more of polycarbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC).

[0065] The electrochemical performance tests include charge / discharge capacity, cycle life, and coulombic efficiency.

[0066] The present invention will be further described in detail below through embodiments. These descriptions are not intended to further limit the scope of the present invention. Those skilled in the art should understand that equivalent substitutions or corresponding improvements made to the technical features of the present invention still fall within the protection scope of the present invention.

[0067] Example 1

[0068] Ethylene glycol and lactic acid were mixed at a molar ratio of 1:1 and heated and stirred at 60°C for 30 min to obtain a eutectic solvent. Waste LiNi... 0.6 Co 0.2 Mn 0.2 The O2 positive electrode sheet was heat-treated at 500-600℃ for 0.5-1.5h to remove the conductive agent and binder. After peeling off the aluminum sheet, the positive electrode active material was obtained. The eutectic solvent and the positive electrode active material were mixed at a solid-liquid ratio of 30g / L and leached at 100℃ for 180min. After vacuum filtration, a nickel-cobalt-manganese co-precipitated product and a lithium-rich solution were obtained. The lithium leaching efficiency was 100%, and the precipitation efficiencies of nickel, cobalt, and manganese were 99.11%, 99.37%, and 90.78%, respectively.

[0069] The nickel-cobalt-manganese coprecipitate was washed three times with anhydrous ethanol, dried overnight at 60°C, and then calcined in a muffle furnace at 500°C for 6 hours to obtain the nickel-cobalt-manganese intermediate oxide. Lithium carbonate was obtained by adjusting the pH of the lithium-rich solution and adding sodium carbonate solution, reacting at 90°C for 90 minutes. The molar relationships are as follows: like Figure 2 As shown, the synthesized Li₂CO₃ has good crystallinity and high purity.

[0070] The prepared nickel-cobalt-manganese intermediate oxide and Li₂CO₃ were mixed uniformly by ball milling with anhydrous ethanol dropwise. The mixture was then calcined at 500℃ for 6 hours, followed by calcination at 850℃ for 12 hours to obtain regenerated cathode powder. The morphology and XRD patterns of the nickel-cobalt-manganese co-precipitate, nickel-cobalt-manganese intermediate oxide, and regenerated cathode powder are shown below. Figure 3 , 4 As shown.

[0071] The synthesized regenerated positive electrode powder was coated into positive electrode sheets using a blade method. Regenerated button cells were then assembled in the following order: negative electrode shell - spring sheet - spacer - lithium sheet - electrolyte - separator - electrolyte - positive electrode sheet - spacer - positive electrode shell. Their electrochemical performance was then tested. After 100 cycles, the regenerated button cells maintained excellent electrochemical performance, achieving a capacity of 150 mAh / g and a coulombic efficiency of 99%. Figure 5 ).

[0072] Cyclic stability tests were conducted on the lithium-rich solution. After repeating the same leaching steps five times, the leaching efficiency for lithium and the precipitation efficiency for nickel, cobalt, and manganese remained high. Figure 6 ).

[0073] Example 2

[0074] Ethylene glycol and lactic acid were mixed at a molar ratio of 2:1 and heated and stirred at 60°C for 20 min to obtain a eutectic solvent. Waste LiNi... 0.8 Co 0.1 Mn 0.1 The O2 positive electrode sheet was heat-treated at 500-600℃ for 0.5-1.5h to remove the conductive agent and binder. After peeling off the aluminum sheet, the positive electrode active material was obtained. The eutectic solvent and the positive electrode active material were mixed at a solid-liquid ratio of 20g / L and leached at 100℃ for 180min. After vacuum filtration, a nickel-cobalt-manganese co-precipitated product and a lithium-rich solution were obtained. The lithium leaching efficiency was 100%, and the precipitation efficiencies of nickel, cobalt, and manganese were 96.82%, 98.30%, and 94.42%, respectively.

[0075] The nickel-cobalt-manganese coprecipitate was washed three times with anhydrous ethanol, dried overnight at 60°C, and then calcined in a muffle furnace at 500°C for 3 hours to obtain nickel-cobalt-manganese intermediate oxides. Lithium carbonate precipitate was obtained by adjusting the pH of the lithium-rich solution and adding sodium carbonate solution, reacting at 90°C for 120 minutes. The molar relationships are as follows:

[0076] The prepared nickel-cobalt-manganese intermediate oxide and Li2CO3 were mixed evenly by ball milling with anhydrous ethanol dropwise. Then, the mixture was calcined at 500℃ for 6 hours and then calcined at 900℃ for 12 hours to obtain regenerated cathode powder.

[0077] The synthesized regenerated cathode powder was coated into cathode sheets using a blade method. Regenerated button cells were then assembled in the following order: negative electrode shell - spring sheet - spacer - lithium sheet - electrolyte - separator - electrolyte - cathode sheet - spacer - cathode shell. Their electrochemical performance was then tested. After 200 cycles, the regenerated button cells maintained excellent electrochemical performance, achieving a capacity of 147 mAh / g and a coulombic efficiency of 98%.

[0078] Example 3

[0079] Ethylene glycol and lactic acid were mixed at a molar ratio of 1:2 and heated and stirred at 50°C for 60 min to obtain a eutectic solvent. Waste LiNi... 0.5 Co 0.2 Mn 0.3 The O2 positive electrode sheet was heat-treated at 500-600℃ for 0.5-1.5h to remove the conductive agent and binder. After peeling off the aluminum sheet, the positive electrode active material was obtained. The eutectic solvent and the positive electrode active material were mixed at a solid-liquid ratio of 30g / L and leached at 120℃ for 120min. Vacuum filtration was then performed to obtain a nickel-cobalt-manganese coprecipitate and a lithium-rich solution. The lithium leaching efficiency was 100%, and the precipitation efficiencies of nickel, cobalt, and manganese were 95.78%, 96.44%, and 84.37%, respectively.

[0080] The nickel-cobalt-manganese coprecipitate was washed three times with anhydrous ethanol, dried overnight at 60°C, and then calcined in a muffle furnace at 450°C for 3 hours to obtain nickel-cobalt-manganese intermediate oxides. Lithium carbonate precipitate was obtained by adjusting the pH of the lithium-rich solution and adding sodium carbonate solution, reacting at 90°C for 120 minutes. The molar relationships are as follows:

[0081] The prepared nickel-cobalt-manganese intermediate oxide and Li2CO3 were mixed evenly by ball milling with anhydrous ethanol dropwise. Then, the mixture was calcined at 500℃ for 5 hours and then calcined at 800℃ for 10 hours.

[0082] The synthesized regenerated cathode powder was coated into cathode sheets using a blade method. Button cells were then assembled in the following order: negative electrode shell - spring sheet - spacer - lithium sheet - electrolyte - separator - electrolyte - cathode sheet - spacer - cathode shell. Their electrochemical performance was then tested. After 50 cycles, the regenerated button cells maintained excellent electrochemical performance, achieving a capacity of 151 mAh / g and a coulombic efficiency of 99%.

[0083] Comparative Example 1

[0084] Choline chloride and lactic acid were mixed at a molar ratio of 1:2 and heated and stirred at 60°C for 30 min to obtain a eutectic solvent. Waste LiNi... 0.6 Co 0.2 Mn 0.2The O2 positive electrode sheet was heat-treated at 500-600℃ for 0.5-1.5h to remove the conductive agent and binder. After peeling off the aluminum sheet, the positive electrode active material was obtained. A eutectic solvent and the positive electrode active material were mixed at a solid-liquid ratio of 30g / L and leached at 100℃ for 180min. Vacuum filtration yielded a filter residue containing nickel, cobalt, and manganese, and a solution containing four metal elements. The leaching efficiencies for lithium, nickel, cobalt, and manganese were 100%, 2.2%, 51.5%, and 74.3%, respectively. The difference between the nickel-cobalt-manganese filter residue and the nickel-cobalt-manganese coprecipitate obtained in the example is that the nickel-cobalt-manganese filter residue was incompletely leached positive electrode powder, while the coprecipitate was a new substance formed by coordination reaction with the eutectic solvent. This leaching agent did not achieve selective separation of lithium from other metals or coprecipitation of nickel, cobalt, and manganese.

[0085] Comparative Example 2

[0086] Choline chloride and lactic acid were mixed in a 1:1 molar ratio and heated and stirred at 60°C for 30 min to obtain a eutectic solvent. Waste LiNi... 0.6 Co 0.2 Mn 0.2 The O2 positive electrode sheet was heat-treated at 500-600℃ for 0.5-1.5h to remove the conductive agent and binder. After peeling off the aluminum sheet, the positive electrode active material was obtained. A eutectic solvent and the positive electrode active material were mixed at a solid-liquid ratio of 30g / L, and leached at 100℃ for 180min. Vacuum filtration yielded a filter residue containing lithium, nickel, cobalt, and manganese, and a solution containing the four metal elements. The leaching efficiencies for lithium, nickel, cobalt, and manganese were 88.7%, 21.2%, 77.5%, and 75.3%, respectively. This leaching agent did not achieve selective separation of lithium from other metals or co-precipitation of nickel, cobalt, and manganese.

[0087] Comparative Example 3

[0088] Tartaric acid and ethylene glycol were mixed at a molar ratio of 1:2 and heated and stirred at 60°C for 30 min to obtain a eutectic solvent. Waste LiNi... 0.6 Co 0.2 Mn 0.2 The O2 positive electrode sheet was heat-treated at 500-600℃ for 0.5-1.5h to remove the conductive agent and binder. After peeling off the aluminum sheet, the positive electrode active material was obtained. A eutectic solvent and the positive electrode active material were mixed at a solid-liquid ratio of 30g / L, and leached at 100℃ for 180min. Vacuum filtration yielded a filter residue containing lithium, nickel, cobalt, and manganese, and a solution containing the four metal elements. The leaching efficiencies for lithium, nickel, cobalt, and manganese were 47.8%, 30.1%, 29.8%, and 29.9%, respectively. This leaching agent did not achieve selective separation of lithium from other metals or co-precipitation of nickel, cobalt, and manganese.

[0089] Comparative Example 4

[0090] Malic acid and ethylene glycol were mixed at a molar ratio of 1:2 and heated and stirred at 60°C for 30 min to obtain a eutectic solvent. Waste LiNi... 0.6 Co 0.2 Mn 0.2 The O2 positive electrode sheet was heat-treated at 500-600℃ for 0.5-1.5h to remove the conductive agent and binder. After peeling off the aluminum sheet, the positive electrode active material was obtained. A eutectic solvent and the positive electrode active material were mixed at a solid-liquid ratio of 30g / L, and leached at 100℃ for 180min. Vacuum filtration yielded a filter residue containing lithium, nickel, cobalt, and manganese, and a solution containing the four metal elements. The leaching efficiencies for lithium, nickel, cobalt, and manganese were 63.1%, 55%, 54.8%, and 53.9%, respectively. This leaching agent did not achieve selective separation of lithium from other metals or co-precipitation of nickel, cobalt, and manganese.

[0091] Comparative Example 5

[0092] Lactic acid and ethylene glycol were mixed at a molar ratio of 1:20 and heated and stirred at 60°C for 30 min to obtain a eutectic solvent. Waste LiNi... 0.6 Co 0.2 Mn 0.2 The O2 positive electrode sheet was heat-treated at 500-600℃ for 0.5-1.5h to remove the conductive agent and binder. After peeling off the aluminum sheet, the positive electrode active material was obtained. A eutectic solvent and the positive electrode active material were mixed at a solid-liquid ratio of 30g / L, and leached at 100℃ for 180min. Vacuum filtration yielded a filter residue containing lithium, nickel, cobalt, and manganese, and a solution containing the four metal elements. The leaching efficiencies for lithium, nickel, cobalt, and manganese were 37.6%, 12.2%, 10.8%, and 10.7%, respectively. This leaching agent system did not achieve selective separation of lithium from other metals or co-precipitation of nickel, cobalt, and manganese.

[0093] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for recycling and utilizing cathode materials from waste ternary lithium batteries, characterized in that, Lithium in waste ternary lithium battery cathode materials is selectively leached using a eutectic solvent to obtain a lithium-rich solution, while nickel, cobalt, and manganese in waste ternary lithium battery cathode materials are simultaneously leached to directly obtain nickel-cobalt-manganese coprecipitates. The recycling method specifically includes the following steps: Waste ternary lithium battery cathode materials are pretreated at 500-600℃ for 0.5-1.5 h to remove conductive agents and binders from the cathode materials, thereby obtaining cathode active materials. The positive electrode active material is added to a eutectic solvent and leached to obtain a nickel-cobalt-manganese coprecipitate and a lithium-rich solution. The leaching conditions are leaching at 100°C for 180 min or leaching at 120°C for 120 min. The solid-liquid ratio of the positive electrode active material and the eutectic solvent is 10-100 g / L; The eutectic solvent is composed of ethylene glycol and lactic acid, wherein the molar ratio of ethylene glycol to lactic acid is 1:10-10:

1.

2. The recycling method according to claim 1, characterized in that, The molar ratio of ethylene glycol to lactic acid is 1:2-2:

1.

3. The recycling method according to claim 1, characterized in that, The method for preparing the eutectic solvent includes the following steps: Ethylene glycol and lactic acid are mixed in a certain proportion and heated and stirred at 50-120℃ for 20-120 min to obtain the final product.

4. The recycling method according to claim 1, characterized in that, The recycling method further includes the following steps: After solid-liquid separation of lithium-rich solution and nickel-cobalt-manganese coprecipitate, a precipitant is added to the lithium-rich solution to obtain lithium-rich precipitate, and the nickel-cobalt-manganese coprecipitate is calcined to obtain nickel-cobalt-manganese cathode intermediate oxide. Lithium-rich precipitate and nickel-cobalt-manganese cathode intermediate oxide are mixed and calcined to obtain regenerated cathode powder; Regenerated ternary lithium batteries were prepared using the obtained recycled cathode powder.

5. The recycling method according to claim 1, characterized in that, The cathode material of the waste ternary lithium batteries includes LiNi. 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2 and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 One or more of O2.

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