Efficient recovery method of lithium ion battery ternary cathode material based on deep eutectic solvent

Abstract

The application discloses a method for efficiently recycling ternary positive materials of lithium ion batteries based on a low eutectic solvent, and belongs to the technical field of recycling waste lithium ion batteries. The method mainly comprises the following steps: mildly stripping the ternary positive plate obtained by disassembling in a first DES stripping solvent prepared from benzyltriphenylphosphonium chloride and octanoic acid, washing, drying, crushing, screening and grinding to obtain ternary positive fine powder; and efficiently leaching the ternary positive fine powder in a second DES leaching solvent prepared from acetamide and sulfamic acid. The application realizes lossless stripping of waste ternary positive materials and current collectors by using a novel low eutectic solvent, and realizes efficient leaching of valuable metals in the ternary positive materials by using another novel low eutectic solvent, thereby achieving the purposes of realizing a whole process that is green, low in consumption, high in metal recovery rate and excellent in performance of the prepared batteries.

Description

Technical Field

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

[0002] With the explosive growth of the new energy vehicle industry, a large number of lithium-ion batteries are about to reach the end of their service life. The ternary cathode materials of these waste lithium-ion batteries contain high-value metals such as lithium, nickel, cobalt, and manganese, and their efficient recycling plays a crucial role in resource recycling.

[0003] Hydrometallurgical technology, as the mainstream process in the current metallurgical industry, typically involves a series of key steps, including discharge dismantling, crushing and sorting, stripping of cathode materials, acid leaching, and extraction separation. These steps not only demonstrate the advantages of hydrometallurgy in environmental protection and efficient resource utilization, but also achieve significant results in processing low-grade ores, recycling waste, and extracting valuable metals. In the stripping stage, N-methylpyrrolidone (NMP) is currently widely used as the stripping solvent. However, NMP is expensive and highly toxic; its strong polarity and high-temperature characteristics can lead to the loss of valuable metal ions from ternary cathode materials, thus affecting the performance of subsequent battery fabrication. Furthermore, in the leaching stage, traditional methods use a combination of strong inorganic acids (such as sulfuric acid and hydrochloric acid) and reducing agents (such as hydrogen peroxide). This system is highly corrosive, producing toxic gases such as chlorine and sulfur dioxide, as well as large amounts of saline wastewater, resulting in high costs for subsequent wastewater treatment.

[0004] Therefore, it is urgent to develop a green, efficient, low-cost, and end-to-end recycling process that can maintain the high value of ternary cathode materials. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned deficiencies of the prior art and provide a highly efficient recycling method for ternary cathode materials of lithium-ion batteries based on a eutectic solvent (DES). Specifically, it uses a specific eutectic solvent to achieve non-destructive stripping of waste ternary cathode materials from the current collector, and another specific eutectic solvent to achieve efficient leaching of valuable metals from the ternary cathode materials. This invention achieves a green, low-consumption process, high metal recovery rate, and excellent battery performance through the design of two novel DES solvents with specific functions, used for the gentle stripping of ternary cathode materials and the efficient leaching of valuable metals, respectively.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] A method for efficient recovery of ternary cathode materials for lithium-ion batteries based on a eutectic solvent, comprising:

[0008] Step S01: Discharge and disassemble the waste lithium-ion battery, and remove the ternary cathode sheet;

[0009] Step S02: Using benzyltriphenylphosphine chloride as a hydrogen bond acceptor and octanoic acid as a hydrogen bond donor, the first DES stripping solvent is obtained by heating and stirring.

[0010] Step S03: Immerse the ternary cathode sheet in the first DES stripping solvent. After the reaction is complete, a ternary cathode material is obtained.

[0011] Step S04: The ternary cathode material is crushed, sieved and ground sequentially to obtain ternary cathode fine powder;

[0012] Step S05: Using acetamide as a hydrogen bond acceptor and aminosulfonic acid as a hydrogen bond donor, the second DES leaching solvent is obtained by heating and stirring.

[0013] Step S06: Add the ternary cathode fine powder to the second DES leaching solvent, leach under heating and stirring, and obtain the leaching solution after filtration.

[0014] Optionally, in step S01, the waste lithium-ion battery is one or more of the following: waste NCM811 lithium-ion battery, waste NCM622 lithium-ion battery, and waste NCM523 lithium-ion battery.

[0015] Optionally, in step S02, the molar ratio of benzyltriphenylphosphine chloride to octanoic acid is 1:(1-3), the heating temperature is 50-80℃, the stirring time is 30-90 min, and the stirring speed is 300-500 r / min.

[0016] Optionally, in step S03, the reaction temperature is 25-60°C, the reaction time is 1-15 min, and the mass ratio of the ternary positive electrode to the first DES stripping solvent is 1:(1-20).

[0017] Optionally, in step S04, before crushing the ternary cathode material, washing and drying are also included.

[0018] Optionally, the cleaning agent used in the washing process is pure water and ethanol, the drying temperature is 60-80℃, and the sieve mesh size is 200-500 mesh.

[0019] Optionally, in step S05, the molar ratio of acetamide to aminosulfonic acid is 1:(1-3), the heating temperature is 50-80℃, the stirring time is 30-90 min, and the stirring speed is 300-500 r / min.

[0020] Optionally, in step S06, the mass ratio of the ternary cathode fine powder to the second DES leaching solvent is 1:(10-50), the heating temperature is 50-100℃, the leaching time is 60-120min, and the stirring speed is 300-500r / min.

[0021] Optionally, in step S06, the leaching rates of lithium, nickel, cobalt, and manganese in the leachate all reach 98% or higher.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention uses green and low-cost DES solvent throughout the process, replacing toxic NMP and highly corrosive inorganic acids, eliminating the generation of harmful gases and waste liquids from the source, making the process safer.

[0024] (2) The first DES stripping solvent achieves efficient stripping under mild conditions (normal pressure, medium temperature). This process preserves the value of the ternary cathode material to the maximum extent. The loss rate of lithium, nickel, cobalt, and manganese ions in the ternary cathode material before and after stripping is less than 0.5% (0.5%). Furthermore, the second DES leaching solvent has an extremely high leaching rate for valuable metals. The recovery rates of lithium, nickel, cobalt, and manganese can all reach over 98%, which is more efficient than or equivalent to the traditional acid leaching method.

[0025] (3) Due to the gentle stripping process and the ease with which DES can be removed by water washing, the structure and electrochemical properties of the ternary cathode powder are perfectly preserved after stripping. By reassembling it into a button cell, the capacity retention rate is greater than 90% after 500 cycles, and its electrochemical performance is close to that of batteries made from commercial ternary cathode materials, which shows the technical feasibility of the direct recycling route. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a high-efficiency recycling method for ternary cathode materials of lithium-ion batteries based on a eutectic solvent, as shown in Example 1.

[0027] Figure 2 The image shows an optical photograph obtained after peeling off the ternary cathode sheet in Example 1, where (a) is the ternary cathode material and (b) is aluminum foil.

[0028] Figure 3 This is a graph showing the first three charge-discharge curves of a button battery assembled from ternary cathode powder in Example 1.

[0029] Figure 4 This is a graph showing the first three charge-discharge curves of a button battery assembled from ternary cathode powder in Example 2.

[0030] Figure 5This is a graph showing the first three charge-discharge curves of the ternary cathode powder assembled into a button battery in Example 3.

[0031] Figure 6 The first three charge-discharge curves of the ternary cathode powder assembled into a button cell in Comparative Example 1.

[0032] Explanation of the labeling in the attached diagram: 1st represents the first lap, 2nd represents the second lap, and 3rd represents the third lap. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0034] This invention provides an efficient method for recovering ternary cathode materials from lithium-ion batteries based on a eutectic solvent, comprising the following steps:

[0035] Step S01: Discharge and disassemble the waste lithium-ion battery, and remove the ternary cathode sheet;

[0036] Step S02: Using benzyltriphenylphosphine chloride as a hydrogen bond acceptor and octanoic acid as a hydrogen bond donor, a uniform and transparent first DES stripping solvent is obtained by heating and stirring.

[0037] Step S03: Immerse the ternary cathode sheet in the first DES stripping solvent. After the reaction is completed, filter and separate to obtain the ternary cathode material, and at the same time obtain the current collector (such as aluminum foil) and the first DES stripping solvent that can be recycled.

[0038] Step S04: The ternary cathode material is crushed (e.g., mechanically crushed), sieved and ground sequentially to obtain ternary cathode fine powder for subsequent electrochemical performance testing and leaching;

[0039] Step S05: Using acetamide as a hydrogen bond acceptor and aminosulfonic acid as a hydrogen bond donor, a uniform and transparent second DES leaching solvent is obtained by heating and stirring.

[0040] Step S06: Add the ternary cathode fine powder to the second DES leaching solvent, leach under heating and stirring, and obtain the leaching solution after filtration.

[0041] This invention employs a first DES stripping solvent, prepared from benzyltriphenylphosphine chloride and octanoic acid, to gently strip spent ternary cathode sheets. This results in a loss rate of less than 0.5% of valuable metals in the stripped ternary cathode material, maximizing the preservation of its value. Furthermore, the resulting fine ternary cathode powder, when assembled into button batteries, exhibits electrochemical performance comparable to batteries made from the new materials. Additionally, a second DES leaching solvent, prepared from acetamide and aminosulfonic acid, enables highly efficient leaching of valuable metals from the ternary cathode material. By designing two novel DES solvents with distinct functions for the gentle stripping of ternary cathode materials and the highly efficient leaching of valuable metals, this invention achieves a green, low-consumption process with high metal recovery rates and excellent battery performance in the reconstituted form.

[0042] Specifically, since most DES stripping studies focus on strongly acidic systems, such systems exacerbate metal leaching. The first DES stripping solvent in this embodiment is near neutral and possesses strong hydrogen bond breaking ability and specific swelling capacity. Benzyltriphenylphosphine chloride is selected as the hydrogen bond acceptor, whose larger molecular size and aromatic structure provide better affinity for binders such as PVDF. Octanoic acid is selected as the hydrogen bond donor; its long-chain fatty acid hydrophobic tail chain generates additional interactions with PVDF, thereby enhancing the stripping effect. Furthermore, octanoic acid is a weak acid, protecting current collectors such as aluminum foil and reducing metal leaching. The first DES stripping solvent in this embodiment has extremely low corrosiveness to aluminum foil, and the loss rate of valuable metals during the stripping process is controlled to within 0.5%, essentially avoiding the loss of valuable metals. The ternary cathode fines obtained after stripping, when assembled into button batteries, exhibit electrochemical performance close to that of commercial ternary cathode materials.

[0043] Furthermore, traditional leaching processes require the addition of a reducing agent (such as H2O2). In the second DES leaching solvent of this invention, acetamide provides a favorable complexing environment, and aminosulfonic acid possesses both acidic and reducing properties. Therefore, without the need for additional reducing agents, it can efficiently destroy the NCM (lithium nickel cobalt manganese oxide) crystal structure, thereby reducing Ni... 3+ Co 3+ Mn 4+ The process involves reduction and dissolution, thereby achieving efficient leaching of valuable metals (Li, Ni, Co, Mn) with a recovery rate of over 98%, which not only simplifies the process but also reduces costs.

[0044] In one embodiment, in step S01, the waste lithium-ion battery is one or more of the following: waste NCM811 lithium-ion battery, waste NCM622 lithium-ion battery, and waste NCM523 lithium-ion battery.

[0045] In one embodiment, in step S01, the ternary positive electrode sheet is cut into 3×5cm sheets for use in the subsequent step S03.

[0046] In one embodiment, in step S02, the molar ratio of benzyltriphenylphosphine chloride to octanoic acid is 1:(1-3), such as 1:1, 1:2, 1:3, etc., the heating temperature is 50-80℃ (such as 50℃, 60℃, 70℃, 80℃, etc.), the stirring time is 30-90min (such as 30min, 40min, 50min, 60min, 70min, 80min, 90min, etc.), and the stirring speed is 300-500r / min (such as 300r / min, 350r / min, 400r / min, 450r / min, 500r / min, etc.).

[0047] In this embodiment, the molar ratio of benzyltriphenylphosphine chloride to octanoic acid is 1:(1-3), and the heating temperature is 50-80°C. Under these conditions, a uniform, transparent DES with a low melting point and suitable viscosity (i.e., the first DES stripping solvent) can be formed. If the temperature is too low, the reaction kinetics are insufficient, and the mixture will remain turbid and viscous for a long time, failing to form a uniform DES and leading to synthesis failure. If the temperature is too high, the octanoic acid will volatilize, affecting the performance of the subsequent stripping solvent.

[0048] In one embodiment, in step S03, the reaction temperature is 25–60°C (e.g., 25°C, 30°C, 45°C, 60°C, etc.), the reaction time is 1–15 min (e.g., 1 min, 5 min, 10 min, 12 min, 13 min, 14 min, 15 min, etc.), and the mass ratio of the ternary positive electrode to the first DES stripping solvent is 1:(1–20), such as 1:1, 1:2, 1:3, 1:5, 1:8, 1:10, 1:15, 1:16, 1:18, 1:20, etc.

[0049] In this embodiment, the reaction temperature is 25–60°C, and the reaction time is 1–15 min. Within this range, the first DES stripping solvent has suitable viscosity, flowability, and reactivity, enabling it to efficiently penetrate to the interface between the ternary cathode material and the current collector (such as aluminum foil). Through interactions such as hydrogen bonding, it gently disrupts the bond between the binder (PVDF) and the aluminum foil, achieving high stripping efficiency (>99%) while minimizing the loss of valuable metal ions in the ternary cathode material and preserving the structural integrity of the material. If the temperature is too low or the time is too short, the reaction will be incomplete, resulting in low stripping efficiency. If the temperature is too high or the time is too long, it will cause irreversible damage to the crystal structure of the ternary cathode material, increasing the dissolution loss of metal ions and resulting in higher energy consumption.

[0050] The mass ratio of the ternary cathode sheet to the first DES stripping solvent is 1:(1~20). Within this range, it ensures that the first DES stripping solvent has sufficient volume to wet, penetrate, and coat the ternary cathode sheet. If the first DES stripping solvent is too little, the ternary cathode sheet cannot be completely immersed and wetted, resulting in uneven stripping, with some material still adhering to the aluminum foil, leading to low stripping efficiency. If the first DES stripping solvent is too much, it will cause solvent waste, increase the cost of subsequent washing and solvent recovery, and its contribution to improving stripping efficiency will no longer be significant.

[0051] In one embodiment, step S04, before crushing the ternary cathode material, further includes washing and drying.

[0052] In one embodiment, the cleaning agent used for washing is pure water and ethanol, the drying temperature is 60-80℃ (e.g., 60℃, 70℃, 80℃, etc.), and the sieve mesh size is 200-500 mesh (e.g., 200 mesh, 350 mesh, 400 mesh, 450 mesh, 500 mesh, etc.).

[0053] In one embodiment, in step S04, the obtained ternary cathode powder is homogenized with Super P (conductive carbon black) and PVDF (polyvinylidene fluoride) in NMP (N-methylpyrrolidone) at a mass ratio of 8:1:1, coated onto aluminum foil, dried, and then die-cut into a cathode sheet. Using lithium metal as the counter electrode, a button cell is assembled in an argon-filled glove box. By reassembling the button cell, its electrochemical performance is comparable to that of a battery prepared with the new materials, demonstrating the technical feasibility of the direct recycling route.

[0054] In one embodiment, in step S05, the molar ratio of acetamide to aminosulfonic acid is 1:(1-3), such as 1:1, 1:2, 1:3, etc., the heating temperature is 50-80℃ (such as 50℃, 60℃, 70℃, 80℃, etc.), the stirring time is 30-90min (such as 30min, 40min, 50min, 60min, 70min, 80min, 90min, etc.), and the stirring speed is 300-500r / min (such as 300r / min, 350r / min, 400r / min, 450r / min, 500r / min, etc.).

[0055] In this embodiment, the molar ratio of acetamide to aminosulfonic acid is 1:(1-3), which ensures that the aminosulfonic acid provides sufficient H+. +The hydrogen bonding between acetamide and the C=O group reaches optimal equilibrium. Heating to 50–80°C allows for the formation of a homogeneous, transparent DES with a low melting point and suitable viscosity (i.e., the second DES leaching solvent). If the temperature is too low, the reaction kinetics are insufficient, and the mixture will remain turbid and viscous for an extended period, failing to form homogeneous DES and leading to synthesis failure. If the temperature is too high, it will cause the decomposition of aminosulfonic acid.

[0056] In one embodiment, in step S06, the mass ratio of the ternary cathode fine powder to the second DES leaching solvent is 1:(10-50), the heating temperature is 50-100℃ (e.g., 50℃, 70℃, 80℃, 100℃, etc.), the leaching time is 60-120min (e.g., 60min, 70min, 80min, 90min, 100min, 110min, 120min, etc.), and the stirring speed is 300-500r / min (e.g., 300r / min, 350r / min, 400r / min, 450r / min, 500r / min, etc.).

[0057] In this embodiment, the mass ratio of the ternary cathode fine powder to the second DES leaching solvent is 1:(10-50). Within this range, the system can provide sufficient reaction interface and mass transfer channels. If the second DES leaching solvent is too little, the slurry will be too viscous and cannot be effectively stirred. The second DES leaching solvent will not be able to fully contact and penetrate into the interior of each ternary cathode fine powder particle, resulting in incomplete leaching reaction and decreased recovery rate. If too much second DES is leached, although the mass transfer effect is good, it will lead to a large waste of the second DES leaching solvent, resulting in poor economic efficiency.

[0058] The heating temperature is 50–100℃, and the leaching time is 60–120 min. Within this range, the viscosity of the second DES leaching solvent is significantly reduced, and the fluidity is enhanced, which is beneficial for mass transfer. At the same time, the acidity and reducing properties of aminosulfonic acid are fully activated, which can efficiently destroy the crystal structure of NCM and remove high-valence Ni. 3+ Co 3+ Mn 4+ Reduced to Ni, which is more soluble in acid 2+ Co 2+ Mn 2+ This allows for metal recovery rates exceeding 98% without the need for additional reducing agents (such as H2O2). However, if the temperature is too low or the time too short, the reaction kinetics are insufficient, resulting in a low leaching rate and failing to achieve the high recovery target. Conversely, if the temperature is too high or the time too long, it will lead to the extensive decomposition of aminosulfonic acid, decreasing the stability of the DES system and diminishing its contribution to improving leaching efficiency. Furthermore, it increases energy consumption and reduces economic viability.

[0059] In one embodiment, in step S06, the leaching rates of lithium, nickel, cobalt, and manganese in the leachate all reach over 98%.

[0060] The present invention will be further described below through several specific embodiments.

[0061] Example 1

[0062] An efficient method for recycling ternary cathode materials for lithium-ion batteries based on eutectic solvents, such as... Figure 1 As shown, it includes the following steps:

[0063] Step S01: Discharge and disassemble the used NCM811 lithium-ion battery, remove the ternary positive electrode sheet, and cut it into 3×5cm sheets.

[0064] Step S02: Benzyltriphenylphosphine chloride and octanoic acid are mixed in a molar ratio of 1:2, and heated and stirred at 60°C for 60 min to obtain a uniform and transparent first DES stripping solvent. The stirring speed is 400 r / min.

[0065] Step S03: Immerse the 3×5cm ternary cathode sheet obtained in step S01 into the first DES stripping solvent in step S02. The mass ratio of the ternary cathode sheet to the first DES stripping solvent is 1:10. Let it stand at 60℃ for 15 minutes to perform stripping. Images before and after stripping are shown below. Figure 2 As shown, where Figure 2 As shown in (a), the disassembled waste ternary cathode sheet can be efficiently separated after specific processing steps. Figure 2 Figure (b) shows the aluminum foil remaining after the ternary cathode material is removed from the ternary cathode sheet. There is no ternary cathode material residue on the surface, which indicates that the removal efficiency of this method can reach more than 99%.

[0066] Step S04: The ternary cathode material obtained in step S03 is washed with pure water and ethanol, dried overnight at 80°C, and then mechanically crushed, sieved, and finely ground to obtain ternary cathode fine powder. Subsequently, the metal content in the ternary cathode fine powder is determined using inductively coupled plasma optical emission spectrometry (ICP-OES), and compared with the metal content in the ternary cathode sheet before peeling. The loss rates of lithium, nickel, cobalt, and manganese ions are calculated, and the loss rate results are shown in Table 1.

[0067] Table 1. ICP test results of ternary cathode materials before and after stripping

[0068]

[0069] Step S05: The ternary cathode powder obtained in step S04 is homogenized with Super P and PVDF in NMP at a mass ratio of 8:1:1, coated onto aluminum foil, dried, and then die-cut into cathode sheets. Using lithium metal as the counter electrode, a button cell is assembled in an argon glove box, and charge-discharge tests are performed at a voltage range of 3–4.3V and a rate of 0.1C. The test results are as follows... Figure 3 As shown, the initial discharge capacity is 180.2 mAh / g, and the capacity retention rate is 91% after 500 cycles. Its electrochemical performance is close to that of batteries made with commercial NCM811 ternary cathode materials.

[0070] Step S06: Acetamide and aminosulfonic acid are mixed in a molar ratio of 1:1.5, and heated and stirred at 80°C for 30 min to obtain a uniform and transparent second DES leaching solvent. The stirring speed is 400 r / min.

[0071] Step S07: Add the ternary cathode fine powder obtained in step S04 to the second DES leaching solvent obtained in step S06. The mass ratio of the ternary cathode fine powder to the second DES leaching solvent is 1:30. Leach for 120 min under heating and stirring at 80℃. After filtration, obtain the leachate and leaching residue. The metal content in the leachate is determined by ICP-OES, and the leaching rates of lithium, nickel, cobalt, and manganese ions are calculated respectively. The leaching rate results are shown in Table 2.

[0072] Table 2. Leaching results of lithium, nickel, cobalt, and manganese

[0073]

[0074] Example 2

[0075] A highly efficient method for recycling ternary cathode materials from lithium-ion batteries based on a eutectic solvent includes the following steps:

[0076] Step S01: Discharge and disassemble the used NCM622 lithium-ion battery, remove the ternary positive electrode sheet, and cut it into 3×5cm sheets.

[0077] Step S02: Benzyltriphenylphosphine chloride and octanoic acid are mixed in a molar ratio of 1:2, and heated and stirred at 60°C for 60 min to obtain a uniform and transparent first DES stripping solvent. The stirring speed is 400 r / min.

[0078] Step S03: Immerse the 3×5cm ternary cathode sheet obtained in step S01 into the first DES stripping solvent in step S02. The mass ratio of the ternary cathode sheet to the first DES stripping solvent is 1:15. Let it stand at 60°C for 20 minutes to strip the cathode. After the reaction is complete, filter and separate the cathode to obtain the ternary cathode material, aluminum foil, and the first DES stripping solvent that can be recycled.

[0079] Step S04: The ternary cathode material obtained in step S03 is washed with pure water and ethanol, dried overnight at 80°C, and then mechanically crushed, sieved, and finely ground to obtain ternary cathode fine powder. Subsequently, the metal content in the ternary cathode fine powder is determined using ICP-OES technology and compared with the metal content in the ternary cathode sheet before stripping. The loss rates of lithium, nickel, cobalt, and manganese ions are calculated, and the loss rate results are shown in Table 3. These loss rate data help evaluate the stability and electrochemical performance of the material.

[0080] Table 3. ICP test results of ternary cathode materials before and after stripping

[0081]

[0082] Step S05: The ternary cathode powder obtained in step S04 is homogenized with Super P and PVDF in NMP at a mass ratio of 8:1:1, coated onto aluminum foil, dried, and then die-cut into cathode sheets. Using lithium metal as the counter electrode, a button cell is assembled in an argon glove box, and charge-discharge tests are performed at a voltage range of 3–4.3V and a rate of 0.1C. The test results are as follows... Figure 4 As shown, the initial discharge capacity is 171.2 mAh / g, and the capacity retention rate is 90.5% after 500 cycles. Its electrochemical performance is close to that of batteries made with commercial NCM622 ternary cathode materials.

[0083] Step S06: Acetamide and aminosulfonic acid are mixed in a molar ratio of 1:1.5, and heated and stirred at 80°C for 30 min to obtain a uniform and transparent second DES leaching solvent. The stirring speed is 400 r / min.

[0084] Step S07: Add the ternary cathode fine powder obtained in step S04 to the second DES leaching solvent obtained in step S06. The mass ratio of the ternary cathode fine powder to the second DES leaching solvent is 1:40. Leach for 90 minutes under heating and stirring at 80°C. After filtration, obtain the leachate. The metal content in the leachate is determined by ICP-OES, and the leaching rates of lithium, nickel, cobalt, and manganese ions are calculated respectively. The leaching rate results are shown in Table 4.

[0085] Table 4. Leaching results of lithium, nickel, cobalt, and manganese

[0086]

[0087] Example 3

[0088] A highly efficient method for recycling ternary cathode materials from lithium-ion batteries based on a eutectic solvent includes the following steps:

[0089] Step S01: Discharge and disassemble the used NCM523 lithium-ion battery, remove the ternary positive electrode sheet, and cut it into 3×5cm sheets.

[0090] Step S02: Benzyltriphenylphosphine chloride and octanoic acid are mixed in a molar ratio of 1:2, and heated and stirred at 60°C for 60 min to obtain a uniform and transparent first DES stripping solvent. The stirring speed is 400 r / min.

[0091] Step S03: Immerse the 3×5cm ternary cathode sheet obtained in step S01 into the first DES stripping solvent in step S02. The mass ratio of the ternary cathode sheet to the first DES stripping solvent is 1:15. Let it stand at 60°C for 30 minutes to strip the cathode. After the reaction is complete, filter and separate the cathode to obtain the ternary cathode material, aluminum foil, and the first DES stripping solvent that can be recycled.

[0092] Step S04: The ternary cathode material obtained in step S03 is washed with pure water and ethanol, dried overnight at 80°C, and then mechanically crushed, sieved, and finely ground to obtain ternary cathode fine powder. Subsequently, the metal content in the ternary cathode fine powder is determined using ICP-OES technology and compared with the metal content in the ternary cathode sheet before stripping. The loss rates of lithium, nickel, cobalt, and manganese ions are calculated, and the loss rate results are shown in Table 5.

[0093] Table 5. ICP test results of ternary cathode materials before and after stripping

[0094]

[0095] Step S05: The ternary cathode powder obtained in step S04 is homogenized with Super P and PVDF in NMP at a mass ratio of 8:1:1, coated onto aluminum foil, dried, and then die-cut into cathode sheets. Using lithium metal as the counter electrode, a button cell is assembled in an argon glove box, and charge-discharge tests are performed at a voltage range of 3–4.3V and a rate of 0.1C. The test results are as follows... Figure 5 As shown, the initial discharge capacity is 163.3 mAh / g, and the capacity retention rate is 93% after 500 cycles. Its electrochemical performance is close to that of batteries made with commercial NCM523 ternary cathode materials.

[0096] Step S06: Acetamide and aminosulfonic acid are mixed in a molar ratio of 1:1.5, and heated and stirred at 80°C for 30 min to obtain a uniform and transparent second DES leaching solvent. The stirring speed is 400 r / min.

[0097] Step S07: Add the ternary cathode fine powder obtained in step S04 to the second DES leaching solvent obtained in step S06. The mass ratio of the ternary cathode fine powder to the second DES leaching solvent is 1:30. Leach for 120 min under heating and stirring at 80℃. After filtration, obtain the leachate. The metal content in the leachate is determined by ICP-OES, and the leaching rates of lithium, nickel, cobalt, and manganese ions are calculated respectively. The leaching rate results are shown in Table 6.

[0098] Table 6. Leaching results of lithium, nickel, cobalt, and manganese

[0099]

[0100] Comparative Example 1

[0101] This comparative example provides a method for removing ternary cathode material from waste ternary cathode sheets, including the following steps:

[0102] The 3×5cm ternary cathode sheet obtained in step S01 of Example 1 was placed in a conventional NMP solvent and peeled off at 80°C for 20 hours. The peeled ternary cathode material was washed with pure water and ethanol, dried overnight at 80°C, and then mechanically crushed, sieved, and finely ground to obtain ternary cathode fine powder. The metal content in the ternary cathode fine powder was determined by ICP-OES technology and compared with the metal content of the ternary cathode sheet before peeling. The loss rates of lithium, nickel, cobalt, and manganese ions were calculated, and the results are shown in Table 7. Table 7 shows that the loss rate is higher than that of this invention. The peeled ternary cathode fine powder was used to manufacture button batteries using the same process. The charge-discharge curves for the first three cycles are shown in the figure. Figure 6 As shown, the first-cycle discharge specific capacity is 172.3 mAh / g, and the electrochemical performance is lower than that of this invention.

[0103] Table 7. ICP test results of ternary cathode materials before and after stripping

[0104]

[0105] Comparative Example 2

[0106] This comparative example provides a method for recycling valuable metals from waste ternary cathode powder, including the following steps:

[0107] Choline chloride and oxalic acid were mixed at a molar ratio of 1:3 and heated and stirred at 80°C for 60 min to obtain a uniform and transparent DES leaching solvent. The stirring speed was 400 r / min. Then, the ternary cathode fine powder obtained in step S04 of Example 1 was added to the DES leaching solvent formed by choline chloride and oxalic acid. The mass ratio of the ternary cathode fine powder to the DES leaching solvent was 1:30. Leaching was carried out at 80°C with stirring for 120 min, and the leachate was obtained after filtration. The metal content in the leachate was determined by ICP-OES, and the leaching rates of lithium, nickel, cobalt, and manganese ions were calculated respectively. The leaching rate results are shown in Table 8. The leaching rate of valuable metals is lower than that of this invention.

[0108] Table 8. Leaching results of lithium, nickel, cobalt, and manganese

[0109]

[0110] In summary, this invention uses a first DES stripping solvent prepared from benzyltriphenylphosphine chloride and octanoic acid to gently strip spent ternary cathode sheets, resulting in a loss rate of less than 0.5% of valuable metals in the stripped ternary cathode material, thus maximizing the preservation of the ternary cathode material's value. Furthermore, the resulting fine ternary cathode powder, when assembled into button batteries, exhibits electrochemical performance comparable to batteries made from the new materials. Additionally, a second DES leaching solvent prepared from acetamide and aminosulfonic acid enables highly efficient leaching of valuable metals from the ternary cathode material. By designing two novel DES solvents with specific functions for the gentle stripping of ternary cathode materials and the highly efficient leaching of valuable metals, this invention achieves a green, low-consumption process with high metal recovery rates and excellent battery performance in the reconstituted form.

[0111] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for efficient recovery of ternary cathode materials for lithium-ion batteries based on a eutectic solvent, characterized in that, include: Step S01: Discharge and disassemble the waste lithium-ion battery, and remove the ternary cathode sheet; Step S02: Using benzyltriphenylphosphine chloride as a hydrogen bond acceptor and octanoic acid as a hydrogen bond donor, the first DES stripping solvent is obtained by heating and stirring. Step S03: Immerse the ternary cathode sheet in the first DES stripping solvent. After the reaction is complete, a ternary cathode material is obtained. Step S04: The ternary cathode material is crushed, sieved and ground sequentially to obtain ternary cathode fine powder; Step S05: Using acetamide as a hydrogen bond acceptor and aminosulfonic acid as a hydrogen bond donor, the second DES leaching solvent is obtained by heating and stirring. Step S06: Add the ternary cathode fine powder to the second DES leaching solvent, leach under heating and stirring, and obtain the leaching solution after filtration; In step S02, the molar ratio of benzyltriphenylphosphine chloride to octanoic acid is 1:(1-3), the heating temperature is 50-80℃, and the stirring time is 30-90 min; In step S05, the molar ratio of acetamide to aminosulfonic acid is 1:(1-3), the heating temperature is 50-80℃, and the stirring time is 30-90 min; In step S06, the mass ratio of the ternary cathode fine powder to the second DES leaching solvent is 1:(10-50), the heating temperature is 50-100℃, and the leaching time is 60-120min.

2. The efficient recovery method for ternary cathode materials of lithium-ion batteries based on a eutectic solvent according to claim 1, characterized in that, In step S01, the waste lithium-ion battery is one or more of the following: waste NCM811 lithium-ion battery, waste NCM622 lithium-ion battery, and waste NCM523 lithium-ion battery.

3. The efficient recovery method for ternary cathode materials of lithium-ion batteries based on a eutectic solvent according to claim 1, characterized in that, In step S02, the stirring speed is 300-500 r / min.

4. The efficient recovery method for ternary cathode materials of lithium-ion batteries based on a eutectic solvent according to claim 1, characterized in that, In step S03, the reaction temperature is 25-60°C, the reaction time is 1-15 min, and the mass ratio of the ternary positive electrode to the first DES stripping solvent is 1:(1-20).

5. The efficient recovery method for ternary cathode materials of lithium-ion batteries based on a eutectic solvent according to claim 1, characterized in that, In step S04, before the ternary cathode material is crushed, it also includes washing and drying.

6. The efficient recovery method for ternary cathode materials of lithium-ion batteries based on a eutectic solvent according to claim 5, characterized in that, The washing process uses pure water and ethanol as cleaning agents, the drying temperature is 60-80℃, and the sieve mesh size is 200-500 mesh.

7. The efficient recovery method for ternary cathode materials of lithium-ion batteries based on a eutectic solvent according to claim 1, characterized in that, In step S05, the stirring speed is 300-500 r / min.

8. The efficient recovery method for ternary cathode materials of lithium-ion batteries based on a eutectic solvent according to claim 1, characterized in that, In step S06, the stirring speed is 300-500 r / min.

9. The efficient recovery method for ternary cathode materials of lithium-ion batteries based on a eutectic solvent according to claim 1, characterized in that, In step S06, the leaching rates of lithium, nickel, cobalt, and manganese in the leachate all reach over 98%.

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