Recovery method of ternary positive electrode material in waste lithium ion battery

Abstract

The invention provides a method for recycling a ternary positive electrode material in a waste lithium ion battery, which comprises the following steps of: pretreating the waste lithium ion battery to obtain a waste ternary positive electrode material; the method comprises the following steps: mixing the waste ternary positive electrode material with a ternary eutectic solvent, carrying out leaching reaction, and carrying out solid-liquid separation to obtain a leaching solution containing nickel, cobalt and manganese; nickel, cobalt and manganese in the leachate containing nickel, cobalt and manganese are recovered; the ternary eutectic solvent is prepared from acetamide, pyruvic acid and sorbitol. By introducing the ternary eutectic solvent composed of acetamide, pyruvic acid and sorbitol, a green, sustainable, economical and feasible recovery process which is mild in condition is developed, efficient leaching of nickel, cobalt, manganese and other valuable metals can be guaranteed, the leaching reaction can be carried out under the mild condition, and the method is suitable for industrial production. And strong acid and an external reducing agent are not needed, so that the energy consumption and the equipment loss are greatly reduced, and the environmental load is remarkably reduced.

Description

Technical Field

[0001] This invention belongs to the field of battery recycling technology, specifically relating to a method for recycling ternary cathode materials from waste lithium-ion batteries. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the amount of waste ternary lithium batteries generated has exploded. As the core component of this type of battery, ternary cathode material is rich in rare and precious metals such as nickel, cobalt, and manganese. Its recycling can not only alleviate the contradiction between supply and demand of mineral resources, but also reduce the environmental risks caused by the random disposal of waste batteries, and has significant economic and environmental value.

[0003] At present, the mainstream technology for recovering valuable metals from waste ternary cathode materials is inorganic acid leaching process. Commonly used leaching agents include sulfuric acid, hydrochloric acid or nitric acid. Although this type of process has the characteristic of fast leaching rate, it has insurmountable defects: (1) High energy consumption. In order to break the crystal structure of ternary cathode materials and improve the metal dissolution efficiency, the leaching system needs to be heated to a high temperature (such as 120°C) and high-intensity stirring needs to be maintained. The heat and mechanical energy consumption is large. In addition, the excess inorganic acid remaining after leaching needs to be neutralized with a large amount of alkali solution. The preparation of alkali solution and the neutralization reaction process further increase energy consumption; (2) Prominent environmental pollution problem. Inorganic acid has strong corrosiveness and is easy to volatilize to produce acid mist, which will corrode production equipment and shorten its service life. Moreover, the leaching waste liquid contains high concentrations of acid radical ions and heavy metal ions. If not handled properly, it will seep into the soil and pollute the groundwater, causing lasting environmental risks.

[0004] Therefore, how to significantly reduce energy consumption and environmental impact of the process while ensuring efficient leaching of valuable metals such as nickel, cobalt, and manganese is a technical challenge that urgently needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for recycling ternary cathode materials from spent lithium-ion batteries. This invention develops a mild, green, sustainable, and economically feasible recycling process by introducing a ternary eutectic solvent composed of acetamide, pyruvate, and sorbitol. Specifically, acetamide acts as a hydrogen bond acceptor, pyruvate as a hydrogen bond donor, and sorbitol as a hydrogen bond donor. Together, they construct a stable and efficient hydrogen bond network, significantly enhancing penetration into the lattice structure of the ternary cathode material. This disrupts the coordination bonds between valuable metal ions and oxygen atoms, promoting the orderly dissociation of the lattice structure and the directional dissolution of valuable metal ions. Furthermore, the carbonyl group in pyruvate is a weak hydrogen bond acceptor, forming additional hydrogen bonds with the amino group of acetamide and the hydroxyl group of sorbitol, further strengthening the interaction within the solvent system. Simultaneously, this carbonyl group can also act as a coordination site, forming stable complexes with the leached metal ions and inhibiting their re-adsorption or aggregation. Therefore, under the action of this ternary eutectic solvent, not only can the efficient leaching of valuable metals such as nickel, cobalt, and manganese be guaranteed, but the leaching reaction can also be carried out under mild conditions without the need for strong acids or external reducing agents. This significantly reduces energy consumption and equipment wear, and avoids the generation of harmful gases and the discharge of acidic wastewater containing heavy metals from the source, thus significantly reducing the environmental impact.

[0006] To achieve this objective, the present invention adopts the following technical solution: This invention provides a method for recycling ternary cathode materials from spent lithium-ion batteries, the recycling method comprising the following steps: Waste lithium-ion batteries are pretreated to obtain waste ternary cathode materials.

[0007] The waste ternary cathode material and ternary eutectic solvent are mixed and leached. After solid-liquid separation, a leaching solution containing nickel, cobalt and manganese is obtained.

[0008] The nickel, cobalt, and manganese in the nickel-cobalt-manganese leaching solution are recovered.

[0009] The ternary eutectic solvent includes acetamide, pyruvic acid, and sorbitol.

[0010] This invention develops a mild, green, sustainable, and economically feasible recycling process by introducing a ternary eutectic solvent composed of acetamide, pyruvate, and sorbitol. Specifically, acetamide acts as a hydrogen bond acceptor, pyruvate as a hydrogen bond donor, and sorbitol as a hydrogen bond donor. Together, they construct a stable and efficient hydrogen bond network, significantly enhancing penetration into the lattice structure of the ternary cathode material. This disrupts the coordination bonds between valuable metal ions and oxygen atoms, promoting the orderly dissociation of the lattice structure and the directional dissolution of valuable metal ions. Furthermore, the carbonyl group in pyruvate is a weak hydrogen bond acceptor, forming additional hydrogen bonds with the amino group of acetamide and the hydroxyl group of sorbitol, further strengthening the interaction within the solvent system. Simultaneously, this carbonyl group can also act as a coordination site, forming stable complexes with the leached metal ions and inhibiting their re-adsorption or aggregation. Therefore, under the action of this ternary eutectic solvent, not only can the efficient leaching of valuable metals such as nickel, cobalt, and manganese be guaranteed, but the leaching reaction can also be carried out under mild conditions without the need for strong acids or external reducing agents. This significantly reduces energy consumption and equipment wear, and avoids the generation of harmful gases and the discharge of acidic wastewater containing heavy metals from the source, thus significantly reducing the environmental impact.

[0011] Preferably, the molar ratio of acetamide, pyruvic acid and sorbitol is (3-4):(2-3):1, wherein the range of acetamide "3-4" can be, for example, 3, 3.2, 3.4, 3.6, 3.8 or 4, and the range of pyruvic acid "2-3" can be, for example, 2, 2.2, 2.4, 2.6, 2.8 or 3.

[0012] In this invention, the ternary eutectic solvent composed of acetamide, pyruvic acid and sorbitol satisfies the above molar ratio requirement, which helps to build a stable and efficient hydrogen bond network, enhances the penetration ability into the lattice structure of the ternary cathode material, promotes the directional dissolution of valuable metal ions, and at the same time ensures the low viscosity and high selectivity of the solvent system.

[0013] Preferably, the solid-liquid ratio of the waste ternary cathode material and the ternary eutectic solvent is (1-100) g:1 L, for example, it can be 1 g:1 L, 5 g:1 L, 10 g:1 L, 20 g:1 L, 40 g:1 L, 60 g:1 L, 80 g:1 L or 100 g:1 L, etc., preferably (20-60) g:1 L.

[0014] In this invention, a suitable solid-liquid ratio is beneficial for balancing the raw material concentration and mass transfer efficiency, avoiding incomplete leaching due to excessively concentrated raw materials or solvent waste due to excessively diluted raw materials, thereby reducing process costs, while ensuring the leaching rate and recovery rate of valuable metals.

[0015] Preferably, the leaching reaction temperature is 10-90℃, for example, it can be 10℃, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃ or 90℃, and preferably 40-60℃.

[0016] Due to the synergistic hydrogen bonding effect of the ternary eutectic solvent, this invention does not require high temperature to destroy the lattice of the cathode material. Therefore, it can be carried out at a relatively mild temperature (10-90℃), which helps to reduce energy consumption and equipment heat loss. At the same time, it avoids solvent evaporation or decomposition caused by high temperature and maintains the stability of the solvent system.

[0017] Preferably, the leaching reaction time is 1-8 hours, for example, it can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours.

[0018] Preferably, the preparation method of the ternary eutectic solvent includes: mixing acetamide, pyruvic acid and sorbitol in a certain proportion, and then stirring evenly at 50-70℃ (e.g., 50℃, 60℃ or 70℃, etc.) and 350-450rpm (e.g., 350rpm, 400rpm or 450rpm, etc.) to obtain the ternary eutectic solvent.

[0019] The method for preparing the ternary eutectic solvent provided by this invention is simple and mild. The resulting ternary eutectic solvent exhibits highly efficient and selective leaching capabilities for nickel, cobalt, and manganese in ternary cathode materials from spent lithium-ion batteries. This solvent system can replace traditional strong acid leaching processes, achieving targeted extraction under mild conditions with high leaching efficiency, simple metal separation, and is environmentally friendly and easily recyclable.

[0020] Preferably, the water content of the ternary eutectic solvent is 0.5-3 wt%, for example, it can be 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, or 3 wt%.

[0021] In this invention, a suitable water content is beneficial for optimizing the hydrogen bond network structure of the eutectic solvent, thereby reducing its viscosity and ion migration resistance, and improving the leaching kinetics and selectivity for target metal ions. Too little water will make the system too viscous, the hydrogen bond interaction too strong, leading to mass transfer difficulties and a decrease in leaching efficiency; too much water will destroy the unique hydrogen bond network structure of the eutectic solvent, losing its advantages such as high selectivity, low volatility, and recyclability.

[0022] Preferably, an anti-interference agent is added to the solution system of the waste ternary cathode material and the ternary eutectic solvent, wherein the anti-interference agent includes sodium fluoride and / or ammonium dihydrogen phosphate.

[0023] In this invention, the anti-interference agent can selectively adsorb residual fluoride ions and phosphate ions in waste ternary cathode materials, preventing them from forming stable complexes with acetamide and pyruvate, thus reducing the solvent leaching activity. This results in a small fluctuation in the leaching rate of the target metal in the leaching reaction, and a low rate of activity decay during solvent recycling.

[0024] Preferably, the mass content of the anti-interference agent is 0.05-0.5 wt%, based on the total mass of the ternary eutectic solvent, for example, it can be 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, or 0.5 wt%.

[0025] Preferably, an auxiliary complexing agent is added to the solution system of the waste ternary cathode material and the ternary eutectic solvent. The auxiliary complexing agent includes any one or a combination of at least two of aminotriacetic acid, disodium ethylenediaminetetraacetate, or trisodium hypotriacetate.

[0026] In this invention, the auxiliary complexing agent and the ternary eutectic solvent can form a synergistic complexing system, which synergistically inhibits the re-adsorption of nickel, cobalt and manganese ions during leaching, and reduces the system's complexing selectivity for iron and aluminum ions.

[0027] Preferably, based on the total mass of the ternary eutectic solvent, the mass content of the auxiliary complexing agent is 0.1-1 wt%, for example, it can be 0.1 wt%, 0.3 wt%, 0.5 wt%, 0.7 wt%, or 0.9 wt%.

[0028] Preferably, the preprocessing method includes: Waste lithium-ion batteries are disassembled to obtain waste positive electrode sheets, which are then subjected to pyrolysis to obtain waste ternary positive electrode materials.

[0029] The pyrolysis treatment temperature is 200-500℃, for example, it can be 200℃, 300℃, 400℃ or 500℃, etc., and the atmosphere for the pyrolysis treatment is an inert atmosphere. For example, it can be a nitrogen atmosphere or an argon atmosphere.

[0030] Preferably, the method for recovering nickel, cobalt, and manganese from the nickel-cobalt-manganese leaching solution includes: A leaching solution containing nickel, cobalt, and manganese is mixed with a precipitant and subjected to a precipitation reaction under alkaline conditions to obtain a mixed precipitate of nickel, cobalt, and manganese.

[0031] The mixed precipitate of nickel, cobalt, and manganese is post-processed to obtain a recovered nickel, cobalt, and manganese product.

[0032] Preferably, the precipitant comprises oxalic acid.

[0033] Preferably, the recycling method includes the following steps: (1) Provide used lithium-ion batteries.

[0034] The waste lithium-ion batteries are discharged and disassembled to obtain waste ternary cathode plates. Then, the waste cathode plates are pyrolyzed in an inert atmosphere at 200-500℃, followed by crushing and sieving to obtain waste ternary cathode material powder with a particle size D50 of 15-25μm (e.g., 15μm, 20μm, or 25μm).

[0035] The method for preparing a ternary eutectic solvent includes: mixing acetamide, pyruvic acid and sorbitol in a molar ratio of (3-4):(2-3):1, and then stirring evenly at 50-70℃ and 350-450rpm to obtain a ternary eutectic solvent with a water content of 0.5-3wt%.

[0036] (2) The waste ternary cathode material powder is added to the ternary eutectic solvent and leaching reaction is carried out for 1-8 hours under constant temperature conditions of 10-90℃. The stirring rate is controlled at 200-1000 rpm (e.g., 200 rpm, 400 rpm, 600 rpm, 800 rpm or 1000 rpm, etc.). After the reaction is completed, the mixture is filtered to obtain a leaching solution containing nickel, cobalt and manganese and filter residue. The solid-liquid ratio of the waste ternary cathode material and the ternary eutectic solvent is (1-100) g:1 L. The total concentration of nickel, cobalt and manganese in the filter residue is <0.05 g / L (e.g., 0.04 g / L, 0.03 g / L, 0.02 g / L or 0.01 g / L, etc.).

[0037] (3) The nickel-cobalt-manganese leaching solution and the precipitant are mixed and a precipitation reaction is carried out under alkaline conditions. After filtration, a mixed precipitate of nickel-cobalt-manganese is obtained. During the precipitation reaction, the pH of the reaction system is 8.5-9.5 (e.g., 8.5, 9 or 9.5, etc.), and the reaction temperature is 35-45℃ (e.g., 35℃, 40℃ or 45℃, etc.). The precipitant includes oxalic acid.

[0038] (4) The mixed precipitate of nickel, cobalt and manganese is washed and dried to obtain nickel, cobalt and manganese recovery product.

[0039] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0040] Compared with the prior art, the present invention has the following beneficial effects: This invention develops a mild, green, sustainable, and economically feasible recycling process by introducing a ternary eutectic solvent composed of acetamide, pyruvate, and sorbitol. Specifically, acetamide acts as a hydrogen bond acceptor, pyruvate as a hydrogen bond donor, and sorbitol as a hydrogen bond donor. Together, they construct a stable and efficient hydrogen bond network, significantly enhancing penetration into the lattice structure of the ternary cathode material. This disrupts the coordination bonds between valuable metal ions and oxygen atoms, promoting the orderly dissociation of the lattice structure and the directional dissolution of valuable metal ions. Furthermore, the carbonyl group in pyruvate is a weak hydrogen bond acceptor, forming additional hydrogen bonds with the amino group of acetamide and the hydroxyl group of sorbitol, further strengthening the interaction within the solvent system. Simultaneously, this carbonyl group can also act as a coordination site, forming stable complexes with the leached metal ions and inhibiting their re-adsorption or aggregation. Therefore, under the action of this ternary eutectic solvent, not only can the efficient leaching of valuable metals such as nickel, cobalt, and manganese be guaranteed, but the leaching reaction can also be carried out under mild conditions without the need for strong acids or external reducing agents. This significantly reduces energy consumption and equipment wear, and avoids the generation of harmful gases and the discharge of acidic wastewater containing heavy metals from the source, thus significantly reducing the environmental impact. Detailed Implementation

[0041] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0042] Example 1 This embodiment provides a method for recycling ternary cathode materials from spent lithium-ion batteries, the recycling method comprising the following steps: (1) Provide used lithium-ion batteries.

[0043] The waste lithium-ion battery is discharged and disassembled to obtain waste ternary cathode plates. Then, the waste cathode plates are pyrolyzed in a nitrogen atmosphere at 350°C, followed by crushing and sieving to obtain waste ternary cathode material powder with a particle size D50 of 20μm.

[0044] The method for preparing a ternary eutectic solvent includes: mixing acetamide, pyruvic acid and sorbitol in a molar ratio of 3.5:2.5:1, and then stirring evenly at 60°C and 400 rpm to obtain a ternary eutectic solvent with a water content of 2 wt%.

[0045] (2) The waste ternary cathode material powder is added to the ternary eutectic solvent and leaching reaction is carried out at a constant temperature of 50°C for 4 hours. The stirring rate is controlled at 600 rpm. After the reaction is completed, the mixture is filtered to obtain a leaching solution containing nickel, cobalt and manganese and filter residue. The solid-liquid ratio of the waste ternary cathode material and the ternary eutectic solvent is 50 g: 1 L. The total concentration of nickel, cobalt and manganese in the filter residue is <0.05 g / L.

[0046] (3) The leaching solution containing nickel, cobalt and manganese is mixed with oxalic acid and subjected to a precipitation reaction under alkaline conditions. After filtration, a mixed precipitate of nickel, cobalt and manganese is obtained. During the precipitation reaction, the pH of the reaction system is 9.0 and the reaction temperature is 40°C.

[0047] (4) The mixed precipitate of nickel, cobalt and manganese is washed and vacuum dried to obtain nickel, cobalt and manganese recovery product.

[0048] Example 2 This embodiment provides a method for recycling ternary cathode materials from spent lithium-ion batteries, the recycling method comprising the following steps: (1) Provide used lithium-ion batteries.

[0049] The waste lithium-ion battery is discharged and disassembled to obtain waste ternary cathode plates. Then, the waste cathode plates are pyrolyzed in an argon atmosphere at 200°C, followed by crushing and sieving to obtain waste ternary cathode material powder with a particle size D50 of 18μm.

[0050] The method for preparing a ternary eutectic solvent includes: mixing acetamide, pyruvic acid and sorbitol in a molar ratio of 3:3:1, and then stirring evenly at 55°C and 380 rpm to obtain a ternary eutectic solvent with a water content of 0.5 wt%.

[0051] (2) The waste ternary cathode material powder is added to the ternary eutectic solvent and leaching reaction is carried out at a constant temperature of 25°C for 8 hours. The stirring rate is controlled at 200 rpm. After the reaction is completed, the mixture is filtered to obtain a leaching solution containing nickel, cobalt and manganese and filter residue. The solid-liquid ratio of the waste ternary cathode material and the ternary eutectic solvent is 30 g: 1 L. The total concentration of nickel, cobalt and manganese in the filter residue is <0.04 g / L.

[0052] (3) The leaching solution containing nickel, cobalt and manganese is mixed with oxalic acid and subjected to precipitation reaction under alkaline conditions. After filtration, a mixed precipitate of nickel, cobalt and manganese is obtained. During the precipitation reaction, the pH of the reaction system is 8.8 and the reaction temperature is 38°C.

[0053] (4) The mixed precipitate of nickel, cobalt and manganese is washed and vacuum dried to obtain nickel, cobalt and manganese recovery product.

[0054] Example 3 This embodiment provides a method for recycling ternary cathode materials from spent lithium-ion batteries, the recycling method comprising the following steps: (1) Provide used lithium-ion batteries.

[0055] The waste lithium-ion batteries are discharged and disassembled to obtain waste ternary cathode plates. Then, the waste cathode plates are pyrolyzed in an argon atmosphere at 500°C, followed by crushing and sieving to obtain waste ternary cathode material powder with a particle size D50 of 22μm.

[0056] The method for preparing a ternary eutectic solvent includes: mixing acetamide, pyruvic acid and sorbitol in a molar ratio of 4:2:1, and then stirring evenly at 65°C and 420 rpm to obtain a ternary eutectic solvent with a water content of 3 wt%.

[0057] (2) The waste ternary cathode material powder is added to the ternary eutectic solvent and leaching reaction is carried out at a constant temperature of 80°C for 1 hour. The stirring rate is controlled at 1000 rpm. After the reaction is completed, the mixture is filtered to obtain a leaching solution containing nickel, cobalt and manganese and filter residue. The solid-liquid ratio of the waste ternary cathode material and the ternary eutectic solvent is 70 g: 1 L. The total concentration of nickel, cobalt and manganese in the filter residue is <0.05 g / L.

[0058] (3) The nickel-cobalt-manganese leaching solution is mixed with oxalic acid and subjected to a precipitation reaction under alkaline conditions. After filtration, a mixed precipitate of nickel-cobalt-manganese is obtained. During the precipitation reaction, the pH of the reaction system is 9.2 and the reaction temperature is 42°C.

[0059] (4) The mixed precipitate of nickel, cobalt and manganese is washed and vacuum dried to obtain nickel, cobalt and manganese recovery product.

[0060] Example 4 The difference between this embodiment and Embodiment 1 is that an anti-interference agent, sodium fluoride, is added to the solution system of the waste ternary cathode material powder and the ternary eutectic solvent; the mass content of the anti-interference agent is 0.25 wt% based on the total mass of the ternary eutectic solvent.

[0061] The remaining recovery methods and parameters are consistent with those in Example 1.

[0062] Example 5 The difference between this embodiment and Embodiment 1 is that an auxiliary complexing agent is added to the solution system of the waste ternary cathode material powder and the ternary eutectic solvent. The auxiliary complexing agent is aminotriacetic acid. Based on the total mass of the ternary eutectic solvent, the mass content of the auxiliary complexing agent is 0.5 wt%.

[0063] The remaining recovery methods and parameters are consistent with those in Example 1.

[0064] Example 6 The difference between this embodiment and Embodiment 1 is that the molar ratio of acetamide, pyruvic acid and sorbitol is 3:5:1.

[0065] The remaining recovery methods and parameters are consistent with those in Example 1.

[0066] Example 7 The difference between this embodiment and Embodiment 1 is that the molar ratio of acetamide, pyruvic acid and sorbitol is 5:2:1.

[0067] The remaining recovery methods and parameters are consistent with those in Example 1.

[0068] Example 8 The difference between this embodiment and Embodiment 1 is that the water content of the ternary eutectic solvent is 0.3 wt%.

[0069] The remaining recovery methods and parameters are consistent with those in Example 1.

[0070] Example 9 The difference between this embodiment and Embodiment 1 is that the water content of the ternary eutectic solvent is 3.5 wt%.

[0071] The remaining recovery methods and parameters are consistent with those in Example 1.

[0072] Example 10 The difference between this embodiment and embodiment 4 is that the mass content of the anti-interference agent is 1 wt%.

[0073] The remaining recovery methods and parameters are consistent with those in Example 4.

[0074] Example 11 The difference between this embodiment and Embodiment 5 is that the mass content of the auxiliary complexing agent is 1.5 wt%.

[0075] The remaining recovery methods and parameters are consistent with those in Example 5.

[0076] Comparative Example 1 The difference between this comparative example and Example 1 is that the acetamide is replaced with choline chloride.

[0077] The remaining recovery methods and parameters are consistent with those in Example 1.

[0078] Comparative Example 2 The difference between this comparative example and Example 1 is that the pyruvic acid is replaced with benzoic acid.

[0079] The remaining recovery methods and parameters are consistent with those in Example 1.

[0080] Comparative Example 3 The difference between this comparative example and Example 1 is that the sorbitol is replaced with ethylene glycol.

[0081] The remaining recovery methods and parameters are consistent with those in Example 1.

[0082] Performance testing Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to test the purity of nickel, cobalt, and manganese in the recovered products obtained from the above examples and comparative examples, and the total recovery rate of nickel, cobalt, and manganese was calculated using the formula: Total recovery rate of nickel, cobalt, and manganese = (Total mass of nickel, cobalt, and manganese in the recovered product / Initial total mass of nickel, cobalt, and manganese in the waste cathode material) × 100%.

[0083] The results are shown in Table 1.

[0084] Table 1 analyze: As shown in Table 1, this invention develops a mild, green, sustainable, and economically feasible recycling process by introducing a ternary eutectic solvent composed of acetamide, pyruvate, and sorbitol. Specifically, acetamide acts as a hydrogen bond acceptor, pyruvate as a hydrogen bond donor, and sorbitol as a hydrogen bond donor. Together, they construct a stable and efficient hydrogen bond network, significantly enhancing penetration into the lattice structure of the ternary cathode material. This disrupts the coordination bonds between valuable metal ions and oxygen atoms, promoting the orderly dissociation of the lattice structure and the directional dissolution of valuable metal ions. Furthermore, the carbonyl group in pyruvate is a weak hydrogen bond acceptor, forming additional hydrogen bonds with the amino group of acetamide and the hydroxyl group of sorbitol, further strengthening the interaction within the solvent system. Simultaneously, this carbonyl group can also act as a coordination site, forming stable complexes with the leached metal ions and inhibiting their re-adsorption or aggregation. Therefore, under the action of this ternary eutectic solvent, not only can the efficient leaching of valuable metals such as nickel, cobalt, and manganese be guaranteed, but the leaching reaction can also be carried out under mild conditions without the need for strong acids or external reducing agents. This significantly reduces energy consumption and equipment wear, and avoids the generation of harmful gases and the discharge of acidic wastewater containing heavy metals from the source, thus significantly reducing the environmental impact.

[0085] As can be seen from the comparison between Example 1 and Examples 6-7, if the molar ratio of acetamide, pyruvic acid and sorbitol is too small, the excess of pyruvic acid will destroy the stability of the hydrogen bond network, resulting in a decrease in the metal ion complexation efficiency, which will not effectively promote lattice dissociation, and the purity and recovery rate will be significantly reduced. If the molar ratio of acetamide, pyruvic acid and sorbitol is too large, the excess of acetamide will increase the solvent viscosity, increase the mass transfer resistance, and result in incomplete leaching, thereby reducing the recovery performance.

[0086] As can be seen from the comparison between Example 1 and Examples 8-9, if the water content of the ternary eutectic solvent is too low, the viscosity of the system will be too high, the hydrogen bonding will be too strong, mass transfer will be difficult, the leaching efficiency will decrease, and the recovery rate will drop to 96.3%. If the water content of the ternary eutectic solvent is too high, the unique hydrogen bonding structure of the eutectic solvent will be destroyed, the selectivity will be reduced, and the target metal cannot be dissolved efficiently and directionally. The purity and recovery rate will both decline slightly.

[0087] As can be seen from the comparison between Example 4 and Example 10, if the mass content of the anti-interference agent is too large, the excess anti-interference agent will adsorb some of the target metal ions, causing the recovery rate to drop from 99.0% to 97.0%, and increasing the subsequent separation cost.

[0088] As can be seen from the comparison between Example 5 and Example 11, if the mass content of the auxiliary complexing agent is too large, the excess complexing agent will form an overly stable complex with the metal ions, increasing the difficulty of the precipitation reaction and causing the recovery rate to drop from 99.1% to 97.5%.

[0089] As can be seen from the comparison between Example 1 and Comparative Examples 1-3, if acetamide is replaced with choline chloride, the hydrogen bond acceptor ability of choline chloride is weaker than that of acetamide, and it cannot effectively destroy the crystal structure of the ternary cathode material, resulting in a significant decrease in leaching efficiency; if pyruvate is replaced with benzoic acid, benzoic acid has no carbonyl coordination site, cannot inhibit the aggregation of metal ions, and has insufficient hydrogen bond donor ability, resulting in a significant deterioration in recovery performance; if sorbitol is replaced with ethylene glycol, ethylene glycol has fewer hydroxyl groups than sorbitol, the hydrogen bond network strength is insufficient, and both leaching selectivity and efficiency are significantly reduced.

[0090] It should be noted that the present invention is illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for recycling ternary cathode materials from spent lithium-ion batteries, characterized in that, The recycling method includes the following steps: Waste lithium-ion batteries are pretreated to obtain waste ternary cathode materials; The waste ternary cathode material and ternary eutectic solvent are mixed and leached. After solid-liquid separation, a leaching solution containing nickel, cobalt and manganese is obtained. The nickel, cobalt, and manganese in the nickel-cobalt-manganese leaching solution are recovered. The ternary eutectic solvent includes acetamide, pyruvic acid, and sorbitol.

2. The recycling method according to claim 1, characterized in that, The molar ratio of acetamide, pyruvic acid and sorbitol is (3-4):(2-3):

1.

3. The recycling method according to claim 1 or 2, characterized in that, The solid-liquid ratio of the waste ternary cathode material and the ternary eutectic solvent is (1-100) g:1 L, preferably (20-60) g:1 L.

4. The recycling method according to any one of claims 1-3, characterized in that, The leaching reaction temperature is 10-90℃, preferably 40-60℃; And / or, the leaching reaction time is 1-8 hours.

5. The recycling method according to any one of claims 1-4, characterized in that, The preparation method of the ternary eutectic solvent includes: mixing acetamide, pyruvic acid and sorbitol in a certain proportion, and then stirring evenly at 50-70℃ and 350-450rpm to obtain the ternary eutectic solvent.

6. The recycling method according to any one of claims 1-5, characterized in that, The water content of the ternary eutectic solvent is 0.5-3 wt%; And / or, an anti-interference agent is also added to the solution system of the waste ternary cathode material and the ternary eutectic solvent, the anti-interference agent including sodium fluoride and / or ammonium dihydrogen phosphate; Based on the total mass of the ternary eutectic solvent, the mass content of the anti-interference agent is 0.05-0.5 wt%.

7. The recycling method according to any one of claims 1-6, characterized in that, An auxiliary complexing agent is also added to the solution system of the waste ternary cathode material and the ternary eutectic solvent. The auxiliary complexing agent includes any one or a combination of at least two of aminotriacetic acid, disodium ethylenediaminetetraacetate or trisodium hypotriacetate. Based on the total mass of the ternary eutectic solvent, the mass content of the auxiliary complexing agent is 0.1-1 wt%.

8. The recycling method according to any one of claims 1-7, characterized in that, The preprocessing method includes: Disassemble waste lithium-ion batteries to obtain waste positive electrode sheets, and then pyrolyze the waste positive electrode sheets to obtain waste ternary positive electrode materials. The pyrolysis treatment temperature is 200-500℃, and the pyrolysis treatment atmosphere is an inert atmosphere.

9. The recycling method according to any one of claims 1-8, characterized in that, The method for recovering nickel, cobalt, and manganese from the nickel-cobalt-manganese leaching solution includes: A leaching solution containing nickel, cobalt, and manganese is mixed with a precipitant and a precipitation reaction is carried out under alkaline conditions to obtain a mixed precipitate of nickel, cobalt, and manganese. The mixed precipitate of nickel, cobalt, and manganese is post-processed to obtain a recovered nickel, cobalt, and manganese product.

10. The recycling method according to any one of claims 1-9, characterized in that, The recycling method includes the following steps: (1) Provide used lithium-ion batteries; The waste lithium-ion battery is discharged and disassembled to obtain waste ternary cathode plates. Then, the waste cathode plates are pyrolyzed in an inert atmosphere at 200-500℃, followed by crushing and sieving to obtain waste ternary cathode material powder with a particle size D50 of 15-25μm. The method for preparing a ternary eutectic solvent includes: mixing acetamide, pyruvic acid and sorbitol in a molar ratio of (3-4):(2-3):1, and then stirring evenly at 50-70℃ and 350-450rpm to obtain a ternary eutectic solvent with a water content of 0.5-3wt%. (2) The waste ternary cathode material powder is added to the ternary eutectic solvent and leaching reaction is carried out at a constant temperature of 10-90℃ for 1-8 hours. The stirring rate is controlled at 200-1000 rpm. After the reaction is completed, the mixture is filtered to obtain a leaching solution containing nickel, cobalt and manganese and filter residue. The solid-liquid ratio of the waste ternary cathode material and the ternary eutectic solvent is (1-100) g:1 L. The total concentration of nickel, cobalt and manganese in the filter residue is <0.05 g / L. (3) The nickel-cobalt-manganese leaching solution and the precipitant are mixed and a precipitation reaction is carried out under alkaline conditions. After filtration, a mixed precipitate of nickel-cobalt-manganese is obtained. In the precipitation reaction, the pH of the reaction system is 8.5-9.5 and the reaction temperature is 35-45℃. The precipitant includes oxalic acid. (4) The mixed precipitate of nickel, cobalt and manganese is washed and dried to obtain nickel, cobalt and manganese recovery product.

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