Method for selectively separating and precipitating lithium, nickel, cobalt and manganese from waste LNCM type lithium ion battery positive electrode material

Abstract

The invention relates to a method for selectively separating and precipitating lithium, nickel, cobalt and manganese from a waste LNCM type lithium ion battery positive electrode material, and belongs to the technical field of recycling of waste lithium batteries. The method comprises the following steps: by taking oxalic acid dihydrate as a hydrogen bond acceptor and DL-carnitine hydrochloride as a hydrogen bond donor, uniformly mixing the hydrogen bond acceptor oxalic acid dihydrate and the hydrogen bond donor DL-carnitine hydrochloride at the temperature of 70-100 DEG C, dissolving in deionized water, and cooling to room temperature to obtain a eutectic solvent; the method comprises the following steps: crushing and screening a waste LNCM type lithium ion battery positive electrode material to obtain waste battery positive electrode powder, adding the waste battery positive electrode powder into a deep eutectic solvent, leaching at the temperature of 70-100 DEG C, and selectively precipitating for 2-10 minutes to obtain a nickel-cobalt-manganese precipitation product and a lithium-rich leaching solution; according to the method, lithium, nickel, cobalt and manganese elements in the waste LNCM lithium ion battery positive electrode material are selectively separated through the eutectic solvent, the reaction time can be greatly shortened, the nickel, cobalt and manganese selective precipitation efficiency can reach 99% or above, and the lithium leaching rate can reach 99% or above.

Description

Technical Field

[0001] The present invention relates to a method for selectively separating and precipitating lithium, nickel, cobalt and manganese from the cathode material of waste LNCM lithium-ion batteries, and belongs to the technical field of recycling of waste lithium batteries. Background Art

[0002] The rapid development of electric vehicles and portable electronic devices has brought about the problem of treating a large number of waste lithium batteries (LIBs), and the demand for pure raw materials has increased significantly. The explosive growth in the demand for Li, Ni, Co and Mn in lithium-ion batteries (LIBs) has exacerbated the imbalance between supply and demand caused by the scarcity of Li, Ni, Co and Mn resources. Recycling Li, Ni, Co, Mn from waste lithium-ion batteries (LIBs) not only eliminates the risk of environmental pollution, but also effectively alleviates the imbalance between supply and demand of key materials, which is crucial for the sustainable development of metal resources.

[0003] At present, valuable metal elements in waste lithium-ion batteries (LIBs) can be extracted by pyrometallurgy, hydrometallurgy or a combination of several recycling technologies. However, pyrometallurgy usually has high energy consumption and produces a large amount of polluting gases, and cannot effectively separate valuable metals. Hydrometallurgy has high recovery efficiency and less secondary pollution. However, hydrometallurgy involves strong acids, strong bases, and various reagents with strong reducibility as auxiliaries; this process will increase industrial costs and produce a large amount of sewage. Therefore, there is an urgent need to find new solvents to treat waste lithium-ion batteries by green, efficient and low-cost methods. Summary of the Invention

[0004] Aiming at the problems of harsh reaction conditions, low leaching rate and complex recovery steps in the current leaching process of lithium-ion battery cathode materials, the present invention proposes a method for selectively separating and precipitating lithium, nickel, cobalt and manganese from the cathode material of waste LNCM lithium-ion batteries. Using oxalic acid dihydrate as a hydrogen bond acceptor and DL-carnitine hydrochloride as a hydrogen bond donor to prepare a deep eutectic solvent, and using the deep eutectic solvent to leach and selectively precipitate and separate lithium, nickel, cobalt and manganese in the cathode material of waste LNCM lithium-ion batteries, which can greatly shorten the reaction time, and the selective precipitation efficiency of nickel, cobalt and manganese can be as high as over 99%, and the lithium leaching rate can be as high as over 99%.

[0005] A method for selectively separating and precipitating lithium, nickel, cobalt and manganese from the cathode material of waste LNCM lithium-ion batteries, the specific steps are as follows:

[0006] (1) Using oxalic acid dihydrate as a hydrogen bond acceptor and DL-carnitine hydrochloride as a hydrogen bond donor, at a temperature of 70-100 °C, mixing the hydrogen bond acceptor oxalic acid dihydrate and the hydrogen bond donor DL-carnitine hydrochloride evenly and dissolving them in deionized water, and cooling to room temperature to obtain a deep eutectic solvent;

[0007] (2) The cathode material of the waste LNCM-type lithium-ion battery is crushed and screened to obtain the waste battery cathode powder. The waste battery cathode powder is added to the deep eutectic solvent, and leached at a temperature of 70-100 °C and selectively precipitated for 2-10 min to obtain a nickel-cobalt-manganese precipitation product and a lithium-rich leachate.

[0008] Preferably, the molar ratio of DL-carnitine hydrochloride to oxalic acid dihydrate in the step (1) is 3:1 to 1:4.

[0009] Preferably, the mass content of deionized water in the deep eutectic solvent in the step (1) is 10-70%.

[0010] Preferably, the solid-liquid ratio of the waste battery cathode powder to the deep eutectic solvent in the step (2) is 10-50:1 g:L.

[0011] The calculation formulas (1)-(2) for the recovery efficiency and leaching rate of Ni, Co, Mn, and Li in the cathode material of the LNCM-type lithium-ion battery are as follows:

[0012]

[0013] In the formula, P is the recovery efficiency of the valuable metal, %.

[0014] c0 and c1 are the concentrations of the valuable metal in the solution before and after recovery, respectively, mg·L -1 ;

[0015] V0 and V1 are the volumes of the solution before and after recovery, respectively, mL.

[0016] η = [(C M ×V) / (w M ×m)]×100% (2)

[0017] In the formula, η is the leaching efficiency of lithium, C M is the metal ion (M = Li) in the leachate, concentration (mg / L), V is the volume of the leachate (L), m is the mass of the cathode active material (g); w M is the mass fraction (wt%) of the metal in the cathode active material.

[0018] The principle of selective precipitation separation of Ni, Co, Mn, and Li in the cathode material of the waste LNCM-type lithium-ion battery by the deep eutectic solvent of the present invention:

[0019] (1) In the deep eutectic solvent, the hydrogen ions ionized from oxalic acid dihydrate combine with the oxygen in the transition metal-oxygen bond in the cathode material, resulting in the disintegration of the layered structure of the cathode material; at the same time, lithium is released from the layered structure; (2) Ni in the cathode material 3+ , Co 3+ , Mn 4+The high-valence metal ions are reduced to Ni by oxalic acid dihydrate 2+ , Co 2+ , Mn 2+ to low-valence metal ions; (3) The reduced low-valence metal ions form complexes with the chloride ions in DL-carnitine hydrochloride. Due to the presence of water, partial hydrolysis of the chlorine complexes occurs to form complexes of hydrated metal ions. Finally, due to the strong chelating effect of oxalic acid dihydrate, it chelates with transition metals to form oxalate precipitates, while lithium oxalate is insoluble in water and remains in the leaching solution to achieve selective separation.

[0020] The beneficial effects of the present invention are as follows:

[0021] (1) In the present invention, DL-carnitine hydrochloride is used as a hydrogen bond acceptor and oxalic acid dihydrate is used as a hydrogen bond donor to prepare a deep eutectic solvent. The deep eutectic solvent is used to selectively precipitate and separate lithium, nickel, cobalt, and manganese in the cathode material of waste LNCM-type lithium-ion batteries, which can greatly shorten the leaching and coprecipitation time. The precipitation efficiency of nickel, cobalt, and manganese can be as high as over 99%, and the leaching efficiency of lithium can be as high as 99%;

[0022] (2) The deep eutectic solvent of the present invention selectively separates lithium, nickel, cobalt, and manganese in the cathode material of waste LNCM-type lithium-ion batteries, avoiding the use of toxic solvents, strong acids, strong bases, and complicated separation processes. Moreover, DL-carnitine hydrochloride and oxalic acid dihydrate can be naturally degraded, reducing the harm to the environment;

[0023] (3) The process of the present invention is simple to operate, has a low reaction temperature, a short leaching time, and extremely high precipitation and leaching efficiencies during the entire selective precipitation and separation process. Specific Embodiments

[0024] The following further elaborates on the present invention in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the content described.

[0025] Example 1: In terms of mass percentage, the cathode material of waste NCM111-type lithium-ion batteries in this example contains 7.1% Li, 20.5% Ni, 20.9% Co, and 19.5% Mn;

[0026] A method for selectively separating and precipitating lithium, nickel, cobalt, and manganese from the cathode material of waste LNCM-type lithium-ion batteries, the specific steps are as follows:

[0027] (1) Using DL-carnitine hydrochloride as a hydrogen bond acceptor and oxalic acid dihydrate as a hydrogen bond donor, at a temperature of 80 °C and stirring (800 rmp / min), ascorbic acid and dimethyl-β-propiothetin are mixed evenly and dissolved in deionized water, and then cooled to room temperature to obtain a deep eutectic solvent; the molar ratio of DL-carnitine hydrochloride to oxalic acid dihydrate is 3:1, and the mass content of deionized water in the deep eutectic solvent is 10%;

[0028] (2) The positive electrode material of waste NCM111 type lithium-ion battery is crushed and screened to obtain the waste battery positive electrode powder. The waste battery positive electrode powder is added to the deep eutectic solvent, and leached at a temperature of 100 °C for 4 min to obtain a lithium nickel cobalt manganese leaching solution; the solid-liquid ratio of the waste battery positive electrode powder to the deep eutectic solvent is g:L = 10:1;

[0029] Use an inductively coupled plasma emission spectrometer to measure the contents of Ni, Co, Mn, and Li in the lithium nickel cobalt manganese leaching solution. The calculation formula for the precipitation efficiency of Ni, Co, and Mn in the waste NCM111 type lithium-ion battery positive electrode powder is:

[0030]

[0031] In the formula, P is the recovery efficiency of valuable metals, %. c0 and c1 are the concentrations of valuable metals in the solution before and after recovery, respectively, mg·L -1 , V0 is the volume of the leaching solution (L), and V0 and V1 are the volumes of the solution before and after recovery, respectively, mL. After the leaching is completed, filter the solution. There is no black residue and the precipitation product is grayish white; it indicates that the valuable metals in the positive electrode material are completely selectively precipitated and separated;

[0032] The precipitation efficiencies of Ni, Co, and Mn are calculated to be 95.70%, 96.15%, and 94.51% respectively through the leaching rate formula.

[0033] Use an inductively coupled plasma emission spectrometer to measure the content of Li in the lithium nickel cobalt manganese leaching solution. The calculation formula for the leaching rate of NLi in the waste NCM111 type lithium-ion battery positive electrode powder is:

[0034] η=[(C M ×V) / (w M ×m)]×100%

[0035] In the formula, η is the leaching efficiency of lithium, C M is the metal ion (M = Li) in the leaching solution, concentration (mg / L), V is the volume of the leaching solution (L), m is the mass of the cathode active material (g); w M is the mass fraction (wt%) of the metal in the cathode active material;

[0036] The leaching rate of Li is calculated to be 98.2% through the leaching rate formula.

[0037] Example 2: The positive electrode material of the waste NCM111 type lithium-ion battery in this example is the same as that in Example 1;

[0038] A method for selectively separating and precipitating lithium, nickel, cobalt, and manganese from the positive electrode material of waste LNCM type lithium-ion batteries, the specific steps are as follows:

[0039] (1) Using DL-carnitine hydrochloride as the hydrogen bond acceptor and oxalic acid dihydrate as the hydrogen bond donor, at a temperature of 70 °C and with stirring (900 rmp / min), ascorbic acid and dimethyl-β-propiothetin were mixed evenly and dissolved in deionized water, and then cooled to room temperature to obtain a deep eutectic solvent; the molar ratio of DL-carnitine hydrochloride to oxalic acid dihydrate was 2:1, and the mass content of deionized water in the deep eutectic solvent was 20%;

[0040] (2) The cathode material of the waste NCM111-type lithium-ion battery was crushed and sieved to obtain the waste battery cathode powder. The waste battery cathode powder was added to the deep eutectic solvent, and leached at a temperature of 90 °C for 8 min to obtain a lithium nickel cobalt manganese leaching solution; the solid-liquid ratio g:L of the waste battery cathode powder to the deep eutectic solvent was 20:1;

[0041] Use an inductively coupled plasma emission spectrometer to determine the contents of Ni, Co, Mn, and Li in the lithium nickel cobalt manganese leaching solution. The calculation formula for the precipitation efficiency of Ni, Co, and Mn in the cathode powder of the waste NCM111-type lithium-ion battery is:

[0042]

[0043] In the formula, P is the recovery efficiency of the valuable metal, %. c0 and c1 are the concentrations of the valuable metal in the solution before and after recovery, respectively, mg·L -1 , V0 is the volume of the leaching solution (L), and V0 and V1 are the volumes of the solution before and after recovery, respectively, mL. After the leaching is completed, the solution is filtered, and there is no black residue and the precipitation product is grayish white; it indicates that the valuable metals in the cathode material are completely selectively precipitated and separated;

[0044] The precipitation efficiencies of Ni, Co, and Mn were calculated to be 99.70%, 99.15%, and 98.11% respectively through the leaching rate formula;

[0045] Use an inductively coupled plasma emission spectrometer to determine the content of Li in the lithium nickel cobalt manganese leaching solution. The calculation formula for the leaching rate of NLi in the cathode powder of the waste NCM111-type lithium-ion battery is:

[0046] η=[(C M ×V) / (w M ×m)]×100%

[0047] In the formula, η is the leaching efficiency of lithium, C M is the metal ion (M = Li) in the leaching solution, concentration (mg / L), V is the volume of the leaching solution (L), m is the mass (g) of the cathode active material; w M is the mass fraction (wt%) of the metal in the cathode active material;

[0048] The leaching rate of Li was calculated to be 98.7% through the leaching rate formula.

[0049] Example 3: The cathode material of the waste NCM111 type lithium-ion battery in this example is the same as that in Example 1;

[0050] A method for selectively separating and precipitating lithium, nickel, cobalt, and manganese from the cathode material of waste LNCM type lithium-ion batteries, the specific steps are as follows:

[0051] (1) Using DL-carnitine hydrochloride as a hydrogen bond acceptor and oxalic acid dihydrate as a hydrogen bond donor, at a temperature of 90 °C and stirring (800 rmp / min), ascorbic acid and dimethyl-β-propiothetin are mixed evenly and dissolved in deionized water, and cooled to room temperature to obtain a deep eutectic solvent; the molar ratio of DL-carnitine hydrochloride to oxalic acid dihydrate is 1:2, and the mass content of deionized water in the deep eutectic solvent is 30%;

[0052] (2) The cathode material of the waste NCM111 type lithium-ion battery is crushed and screened to obtain the cathode powder of the waste battery. The cathode powder of the waste battery is added to the deep eutectic solvent, and leached at a temperature of 80 °C for 6 min to obtain a lithium, nickel, cobalt, and manganese leaching solution; the solid-liquid ratio g:L of the cathode powder of the waste battery to the deep eutectic solvent is 30:1;

[0053] Use an inductively coupled plasma emission spectrometer to measure the contents of Ni, Co, Mn, and Li in the lithium, nickel, cobalt, and manganese leaching solution. The calculation formula for the precipitation efficiency of Ni, Co, and Mn in the cathode powder of the waste NCM111 type lithium-ion battery is:

[0054]

[0055] In the formula, P is the recovery efficiency of valuable metals, %. c0 and c1 are the concentrations of valuable metals in the solution before and after recovery, respectively, mg·L -1 , V0 is the volume of the leaching solution (L), V0 and V1 are the volumes of the solution before and after recovery, respectively, mL. After the leaching is completed, the solution is filtered, and there is no black residue and the precipitate is grayish-white; it indicates that the valuable metals in the cathode material are completely selectively precipitated and separated;

[0056] The precipitation efficiencies of Ni, Co, and Mn are calculated to be 99.70%, 99.15%, and 99.11% respectively through the leaching rate formula;

[0057] Use an inductively coupled plasma emission spectrometer to measure the content of Li in the lithium, nickel, cobalt, and manganese leaching solution. The calculation formula for the leaching rate of NLi in the cathode powder of the waste NCM111 type lithium-ion battery is:

[0058] η=[(C M ×V) / (w M ×m)]×100%

[0059] In the formula, η is the leaching efficiency of lithium, CM where M is the metal ion (M = Li) in the leaching solution, concentration (mg / L), V is the volume of the leaching solution (L), m is the mass of the cathode active material (g); w M is the mass fraction of the metal in the cathode active material (wt%);

[0060] The Li leaching rate was calculated to be 99.7% through the leaching rate formula.

[0061] Example 4: The cathode material of the waste NCM111 type lithium-ion battery in this example is the same as that in Example 1;

[0062] A method for selectively separating and precipitating lithium, nickel, cobalt and manganese from the cathode material of waste LNCM type lithium-ion batteries, the specific steps are as follows:

[0063] (1) Using DL-carnitine hydrochloride as the hydrogen bond acceptor and oxalic acid dihydrate as the hydrogen bond donor, at a temperature of 80 °C and stirring (800 rmp / min), ascorbic acid and dimethyl-β-propiothetin are mixed evenly and dissolved in deionized water, and cooled to room temperature to obtain a deep eutectic solvent; the molar ratio of DL-carnitine hydrochloride to oxalic acid dihydrate is 1:3, and the mass content of deionized water in the deep eutectic solvent is 40%;

[0064] (2) The cathode material of the waste NCM111 type lithium-ion battery is crushed and screened to obtain the cathode powder of the waste battery. The cathode powder of the waste battery is added to the deep eutectic solvent, and leached at a temperature of 90 °C for 6 min to obtain a leaching solution of lithium, nickel, cobalt and manganese; the solid-liquid ratio g:L of the cathode powder of the waste battery to the deep eutectic solvent is 40:1;

[0065] Use an inductively coupled plasma emission spectrometer to measure the contents of Ni, Co, Mn, and Li in the leaching solution of lithium, nickel, cobalt and manganese. The calculation formula for the precipitation efficiency of Ni, Co, and Mn in the cathode powder of the waste NCM111 type lithium-ion battery is:

[0066]

[0067] In the formula, P is the recovery efficiency of valuable metals, %. c0 and c1 are the concentrations of valuable metals in the solution before and after recovery, mg·L -1 , V0 is the volume of the leaching solution (L), V0 and V1 are the volumes of the solution before and after recovery, mL. After the leaching is completed, the solution is filtered, there is no black residue and the precipitation product is grayish white; it indicates that the valuable metals in the cathode material are completely selectively precipitated and separated;

[0068] The precipitation efficiencies of Ni, Co, and Mn were calculated to be 99.33%, 99.21%, and 97.87% respectively through the leaching rate formula;

[0069] Determine the content of Li in the leaching solution of lithium nickel cobalt manganese using an inductively coupled plasma emission spectrometer. The calculation formula for the leaching rate of NLi in the cathode powder of waste NCM111 type lithium-ion batteries is as follows:

[0070] η=[(C M ×V) / (w M ×m)]×100%

[0071] In the formula, η is the leaching efficiency of lithium, C M is the metal ion (M = Li) in the leaching solution, with a concentration of (mg / L), V is the volume of the leaching solution (L), and m is the mass of the cathode active material (g); w M is the mass fraction of the metal in the cathode active material (wt%);

[0072] The leaching rate of Li calculated by the leaching rate formula is 99.1%.

[0073] Example 5: The cathode material of the waste NCM111 type lithium-ion battery in this example is the same as that in Example 1;

[0074] A method for selectively separating and precipitating lithium nickel cobalt manganese from the cathode material of waste LNCM type lithium-ion batteries is as follows:

[0075] (1) Using DL-carnitine hydrochloride as the hydrogen bond acceptor and oxalic acid dihydrate as the hydrogen bond donor, at a temperature of 95 °C and stirring (700 rmp / min), mix ascorbic acid and dimethyl-β-propiothetin evenly and dissolve them in deionized water, and cool to room temperature to obtain a deep eutectic solvent; the molar ratio of DL-carnitine hydrochloride to oxalic acid dihydrate is 1:1, and the mass content of deionized water in the deep eutectic solvent is 40%;

[0076] (2) Crush and screen the cathode material of the waste NCM111 type lithium-ion battery to obtain the cathode powder of the waste battery. Add the cathode powder of the waste battery to the deep eutectic solvent and leach for 6 min at a temperature of 100 °C to obtain a leaching solution of lithium nickel cobalt manganese; the solid-liquid ratio g:L of the cathode powder of the waste battery to the deep eutectic solvent is 35:1;

[0077] Determine the contents of Ni, Co, Mn, and Li in the leaching solution of lithium nickel cobalt manganese using an inductively coupled plasma emission spectrometer. The calculation formula for the precipitation efficiency of Ni, Co, and Mn in the cathode powder of waste NCM111 type lithium-ion batteries is as follows:

[0078]

[0079] In the formula, P is the recovery efficiency of valuable metals, %. c0 and c1 are the concentrations of valuable metals in the solution before and after recovery, respectively, in mg·L -1, where \(V_0\) is the volume of the leaching solution (L), and \(V_0\) and \(V_1\) are the volumes of the solution before and after recovery, respectively, in mL. After the leaching is completed, the solution is filtered, with no black residue and the precipitate product being grayish-white; indicating that the valuable metals in the cathode material are completely selectively precipitated and separated;

[0080] The precipitation efficiencies of Ni, Co, and Mn are calculated to be 99.7%, 99.5%, and 98.3% respectively through the leaching rate formula;

[0081] The content of Li in the lithium nickel cobalt manganese leaching solution is determined using an inductively coupled plasma emission spectrometer. The calculation formula for the leaching rate of \(N_{Li}\) in the cathode powder of waste NCM111 type lithium-ion batteries is:

[0082] \(\eta = [ (C\) M \(\times V) / (w\) M \(\times m) ] \times 100\%\)

[0083] In the formula, \(\eta\) is the leaching efficiency of lithium, \(C\) M is the metal ion (\(M = Li\)) in the leaching solution, with a concentration of (mg / L), \(V\) is the volume of the leaching solution (L), \(m\) is the mass of the cathode active material (g); \(w\) M is the mass fraction (wt%) of the metal in the cathode active material;

[0084] The leaching rate of Li is calculated to be 99.5% through the leaching rate formula.

[0085] Example 6: The cathode material of waste NCM111 type lithium-ion batteries in this example is the same as that in Example 1;

[0086] A method for selectively separating and precipitating lithium nickel cobalt manganese from the cathode material of waste LNCM type lithium-ion batteries, the specific steps are as follows:

[0087] (1) Using DL-carnitine hydrochloride as the hydrogen bond acceptor and oxalic acid dihydrate as the hydrogen bond donor, at a temperature of 100 °C and stirring (700 rmp / min), ascorbic acid and dimethyl-β-propiothetin are mixed evenly and dissolved in deionized water, and cooled to room temperature to obtain a deep eutectic solvent; the molar ratio of DL-carnitine hydrochloride to oxalic acid dihydrate is 1:4, and the mass content of deionized water in the deep eutectic solvent is 70%;

[0088] (2) The cathode material of waste NCM111 type lithium-ion batteries is crushed and screened to obtain the cathode powder of waste batteries. The cathode powder of waste batteries is added to the deep eutectic solvent, and leached at a temperature of 70 °C for 10 min to obtain a lithium nickel cobalt manganese leaching solution; the solid-liquid ratio g:L of the cathode powder of waste batteries to the deep eutectic solvent is 50:1;

[0089] The content of Ni, Co, Mn, and Li in the leaching solution of lithium nickel cobalt manganese was determined using an inductively coupled plasma emission spectrometer. The calculation formula for the precipitation efficiency of Ni, Co, and Mn in the cathode powder of waste NCM111-type lithium-ion batteries is as follows:

[0090]

[0091] In the formula, P is the recovery efficiency of valuable metals, %. c0 and c1 are the concentrations of valuable metals in the solution before and after recovery, respectively, in mg·L -1 , V0 is the volume of the leaching solution (L), and V0 and V1 are the volumes of the solution before and after recovery, respectively, in mL. After the leaching is completed, the solution is filtered. There is no black residue and the precipitation product is grayish-white, indicating that the valuable metals in the cathode material are completely selectively precipitated and separated.

[0092] The precipitation efficiencies of Ni, Co, and Mn were calculated to be 99.60%, 99.05%, and 99.01% respectively through the leaching rate formula.

[0093] The content of Li in the leaching solution of lithium nickel cobalt manganese was determined using an inductively coupled plasma emission spectrometer. The calculation formula for the leaching rate of NLi in the cathode powder of waste NCM111-type lithium-ion batteries is as follows:

[0094] η = [(C M ×V) / (w M ×m)]×100%

[0095] In the formula, η is the leaching efficiency of lithium, C M is the metal ion (M = Li) in the leaching solution, with a concentration of (mg / L), V is the volume of the leaching solution (L), m is the mass of the cathode active material (g); w M is the mass fraction of the metal in the cathode active material (wt%);

[0096] The leaching rate of Li was calculated to be 99.2% through the leaching rate formula.

[0097] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the knowledge scope of those of ordinary skill in the art, various changes can be made without departing from the purpose of the present invention.

Claims

1. A method for selectively separating and precipitating lithium, nickel, cobalt and manganese from waste LNCM type lithium ion battery positive electrode materials, characterized in that: The specific steps are as follows: (1) using oxalic acid dihydrate as a hydrogen bond acceptor and DL-carnitine hydrochloride as a hydrogen bond donor, mixing the hydrogen bond acceptor oxalic acid dihydrate and the hydrogen bond donor DL-carnitine hydrochloride uniformly at a temperature of 70 to 100° C., dissolving the mixture in deionized water, and cooling the mixture to room temperature to obtain a deep eutectic solvent; (2) The waste LNCM type lithium-ion battery positive electrode material is crushed and sieved to obtain waste battery positive electrode powder, the waste battery positive electrode powder is added to a low eutectic solvent, leached and selectively precipitated at a temperature of 70 to 100° C. for 2 to 10 minutes to obtain a nickel-cobalt-manganese precipitation product and a lithium-rich leachate.

2. The method for selectively separating and precipitating lithium, nickel, cobalt and manganese from waste LNCM type lithium ion battery positive electrode materials according to claim 1, characterized in that: In step (1), the molar ratio of DL-carnitine hydrochloride to oxalic acid dihydrate is 3:1 to 1:

4.

3. The method for selectively separating and precipitating lithium, nickel, cobalt and manganese from waste LNCM lithium-ion battery positive electrode materials according to claim 1, characterized in that: The mass content of deionized water in the low eutectic solvent in step (1) is 10-70%.

4. The method for selectively separating and precipitating lithium, nickel, cobalt and manganese from waste LNCM type lithium ion battery positive electrode materials according to claim 1, characterized in that: In step (2), the solid-liquid ratio g:L of the waste battery positive electrode powder and the low eutectic solvent is 10 to 50:1.

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