A method for lithium recycling from lithium ion batteries

Abstract

We provide a method for recycling lithium from lithium-ion batteries in an economical, environmentally efficient, and high-efficiency manner. A method for recycling lithium from a lithium-ion battery, comprising the following steps: (a) a step of obtaining a Li+ leaching solution by adding an oxalic acid-based deep eutectic solvent to black mass obtained from an LCO (Lithium Cobalt Oxide), LMO (Lithium Manganese Oxide), NCM (Nickel Cobalt Manganese), NCMA (Nickel Cobalt Manganese Aluminum), or NCA (Nickel Cobalt Aluminum) lithium-ion battery; (b) a step of adding ammonium chloride (NH4Cl) to the above Li+ leachate and removing the solid precipitate to obtain a lithium-containing filtrate; (c) a step of adding a base to the lithium-containing filtrate to precipitate iron hydroxide (Fe(OH)3) and aluminum hydroxide (Al(OH)3); and (d) Step of recovering the lithium chloride (LiCl) solution.

Description

Technology Field

[0001] The present invention relates to a method for recycling lithium from black mass, which is a positive electrode active material obtained from a lithium-ion battery. Background Technology

[0002] Lithium, an essential component of lithium-ion batteries, is garnering attention as a key raw material in the energy storage and electric vehicle (EV) industries. As high-efficiency energy solutions are emphasized globally, the demand for lithium is projected to increase further. This rise in demand is driven by the transition to a sustainable energy system aimed at achieving carbon neutrality and addressing climate change. However, there is a growing need to develop stable recycling and recovery technologies to mitigate supply chain risks caused by the geopolitical concentration of lithium resources.

[0003] In particular, NCM (lithium nickel cobalt manganese oxide), one of the main cathode materials for lithium-ion batteries, contains not only lithium but also expensive transition metals such as cobalt, nickel, and manganese, so there is significant economic and environmental value in recovering these resources from waste batteries. Given the reality that key materials such as lithium are mainly imported, it is essential to secure technology to recover and recycle metals such as lithium from waste lithium-ion batteries.

[0004] Non-patent document 1 proposes recovering core materials from high-lithium-content raw materials, such as discarded lithium-ion batteries, and reusing them to produce efficient new cathode materials.

[0005] Patent Documents 1 and 2 propose a leaching process using acid and a leaching process using sulfuric acid (H2SO4) and hydrogen peroxide (H2O2). However, in these conventional leaching processes, simultaneous leaching of transition metals (Ni, Co, Mn, etc.) and impurities (Fe, Al, Cu, etc.) occurs, making subsequent purification processes complex, and economic and environmental efficiency are reduced due to problems such as the generation of low-value-added by-products, increased use of chemicals, and wastewater generation.

[0006] Non-patent document 2 proposes a direct regeneration method. However, this method is limited to high-purity NCM, which limits its use and commercialization in large-scale manufacturing processes.

[0007] Therefore, there is a need to develop eco-friendly and low-cost technologies capable of selectively leaching and recovering lithium with high efficiency. Prior art literature

[0008] EP 4 282 997 A2 (2023.11.29.)EP 4 443 601 A1 (2024.10.09.)

[0009] T. Nshizirungu et al. Journal of Hazardous Materials 393 (2020) 122367R. Kim et al. Chemical Engineering Journal 516 (2025) 164065 The problem to be solved

[0010] The present invention aims to solve the above-mentioned problems by providing a method for recovering lithium, specifically lithium chloride (LiCl), which is a recyclable precursor, from waste lithium-ion batteries.

[0011] In particular, the purpose is to provide a practical method that enables selective leaching of lithium and has high lithium recovery efficiency by utilizing a green solvent such as an oxalic acid-based deep eutectic solvent (DES), while minimizing the use of hazardous chemicals. means of solving the problem

[0012] The inventors added an oxalic acid-based deep eutectic solvent to the black mass obtained from a lithium-ion battery to Li + It was discovered that the above objective could be achieved by obtaining a leachate, precipitating and removing iron hydroxide (Fe(OH)3) and aluminum hydroxide (Al(OH)3) from it, and recovering a lithium chloride (LiCl) solution, and thus the present invention was completed.

[0013] The present invention includes the following aspects.

[0014] <1> As a method for recycling lithium from a lithium-ion battery,

[0015] (a) Adding an oxalic acid-based deep eutectic solvent to black mass obtained from a lithium-ion battery to Li + Step of obtaining the leachate;

[0016] (b) The above Li + A step of adding ammonium chloride (NH4Cl) to the leachate and removing the solid precipitate to obtain a lithium-containing filtrate;

[0017] (c) a step of adding a base to the lithium-containing filtrate to precipitate iron hydroxide (Fe(OH)3) and aluminum hydroxide (Al(OH)3); and

[0018] (d) includes a step of recovering a lithium chloride (LiCl) solution, and

[0019] A method for recycling lithium from a lithium-ion battery, wherein the lithium-ion battery is an LCO (Lithium Cobalt Oxide), LMO (Lithium Manganese Oxide), NCM (Nickel Cobalt Manganese), NCMA (Nickel Cobalt Manganese Aluminum), or NCA (Nickel Cobalt Aluminum) battery.

[0020] <2> The above oxalic acid-based deep eutectic solvent is an oxalic acid-choline chloride deep eutectic solvent, a method for recycling lithium from a lithium-ion battery as described in <1>.

[0021] <3> The above oxalic acid-choline chloride deep eutectic solvent is a method for recycling lithium from a lithium-ion battery described in <2>, wherein the molar ratio of oxalic acid to choline chloride is 30:0.1 to 30:10.

[0022] The above Li in step (a) of <4> + A method for recycling lithium from a lithium-ion battery as described in <1>, wherein the concentration of copper in the leaching solution is 2.33 wt% or less.

[0023] A method for recycling lithium from a lithium-ion battery as described in <1>, wherein the oxalic acid-based deep eutectic solvent in step (a) functions as a reducing agent and a leaching agent.

[0024] A method for recycling lithium from a lithium-ion battery described in <1>, wherein the ammonium chloride in step (b) of <6> is added in a molar ratio of 1:1 to 1:5 [oxalic acid: ammonium chloride].

[0025] The method for recycling lithium from a lithium-ion battery described in <1>, wherein the base in step (c) of <7> is ammonium hydroxide (NH4OH).

[0026] Step (d) of <8> is,

[0027] A step of obtaining a first solution by removing iron hydroxide and aluminum hydroxide precipitates from a lithium-containing filtrate, and

[0028] A method for recycling lithium from a lithium-ion battery as described in <1>, comprising the step of washing the removed iron hydroxide and aluminum hydroxide with deionized water to obtain a second solution.

[0029] <9> A method for recycling lithium from a lithium-ion battery as described in <8>, wherein a filter paper having a pore size of 5 μm or less is used in the step of removing iron hydroxide and aluminum hydroxide precipitates from a lithium-containing filtrate to obtain a first solution. Effects of the invention

[0030] According to the present invention, lithium can be recovered and recycled at low cost and high efficiency by using a deep eutectic solvent based on oxalic acid, which is a green solvent. Furthermore, the present invention can provide a sustainable method for recycling lithium with low environmental burden. Brief explanation of the drawing

[0031] FIG. 1 is a flowchart of the method of the present invention for recovering lithium chloride (LiCl) from a lithium-ion battery. Specific details for implementing the invention

[0032] The invention described herein provides a method for recycling lithium from a lithium-ion battery. Specifically, it provides a method for separating and recovering lithium from a positive electrode active material other than lithium present in the black mass obtained from a lithium-ion battery.

[0033] FIG. 1 illustrates the method of the present invention for recovering lithium chloride (LiCl) from a lithium-ion battery in steps.

[0034] The present invention relates to (a) adding an oxalic acid-based deep eutectic solvent to black mass obtained from a lithium-ion battery to Li + It includes the step of obtaining the leachate.

[0035] The above lithium-ion battery may be an LCO (Lithium Cobalt Oxide), LMO (Lithium Manganese Oxide), NCM (Nickel Cobalt Manganese), NCMA (Nickel Cobalt Manganese Aluminum), or NCA (Nickel Cobalt Aluminum) battery, and preferably an NCM battery.

[0036] The black mass obtained from the above lithium-ion battery includes lithium and a positive electrode active material other than lithium. The positive electrode active material other than lithium may include nickel, manganese, cobalt, aluminum, or copper.

[0037] To improve lithium leaching efficiency, it is important to select an appropriate leaching agent. From the perspective of low cost, low toxicity, and low environmental burden, an oxalic acid-based deep eutectic solvent is preferred as the leaching agent. The oxalic acid-based deep eutectic solvent can function not only as a leaching agent but also as a reducing agent.

[0038] The above oxalic acid-based deep eutectic solvent can be prepared by doping oxalic acid with a chloride-based salt, heating at a temperature of 60 to 80°C for about 60 minutes, and then adding deionized water. Choline chloride is preferred as the chloride-based salt doped into oxalic acid. From the perspective of forming optimal conditions for lithium leaching, the oxalic acid-based deep eutectic solvent is preferably an oxalic acid-choline chloride deep eutectic solvent.

[0039] The mechanism by which the oxalic acid-choline chloride deep eutectic solvent leaches lithium from black mass is as follows: C2O4 derived from oxalic acid 2- and Cl derived from choline chloride - Lithium ion (Li + ), iron ions (Fe 2+ / Fe 3+ ) and / or aluminum ions (Al3+ It selectively interacts with ) to form water-soluble lithium oxalates, iron oxalates / chlorides, and aluminum oxalates. Meanwhile, transition metals such as nickel, cobalt, and manganese, C2O4 derived from oxalic acid 2- It reacts with and precipitates in the form of respective insoluble oxalates. This selective solubility enables the separation of lithium from other metals, thereby improving the purity of the extracted lithium. This mechanism plays a key role in recycling processes that improve the lithium recovery rate.

[0040] The above oxalic acid-choline chloride deep eutectic solvent preferably has a molar ratio of oxalic acid to choline chloride of 30:0.1 to 30:10, and more preferably 30:1. When the molar ratio of oxalic acid to choline chloride is within the above range, the lithium leaching efficiency is improved, impurities remaining in the leaching solution are reduced, the chelating performance of oxalic acid against nickel, cobalt, manganese, etc. is maintained, and copper is prevented from being leached together during lithium leaching.

[0041] Step (a) above is initiated by adding an oxalic acid-based deep eutectic solvent to a black mass containing lithium and a non-lithium cathode active material, and heating a mixture of the black mass and an aqueous iron trichloride solution. The addition reaction preferably includes heating at a temperature of 30 to 100°C for 0.5 to 3 hours.

[0042] Li obtained through the above step (a) + The leaching solution contains a significant amount of lithium, but may also contain iron, aluminum, nickel, cobalt, manganese, copper, and graphite. The above Li + If the concentration of copper in the leachate is high, it is difficult to separate copper from the leachate, so it is desirable that the concentration of copper in the leachate be 2.33 wt% or less.

[0043] The present invention comprises: (b) the above Li +The method includes the step of adding ammonium chloride (NH4Cl) to the leachate and removing the solid precipitate to obtain a lithium-containing filtrate.

[0044] Li obtained through the above step (a) + The leaching solution contains metal ions such as lithium, iron, and aluminum as oxalates. Specifically, the above Li + The leachate may contain oxalates such as Li2C2O4, LiHC2O4, FeH(C2O4), Fe2(C2O4)3, AlH(C2O4)3, and Al2C2O4.

[0045] Li + By adding ammonium chloride to the leachate, metal ions existing as oxalates are converted into chlorides, resulting in a solution containing a large amount of lithium chloride.

[0046] Also, Li + By adding ammonium chloride to the leachate, a byproduct may be formed, preferably a solid precipitate. The solid precipitate may contain ammonium oxalate. By filtering and removing the solid precipitate, a lithium-containing filtrate is obtained.

[0047] It is preferable that the above ammonium chloride be added in a molar ratio of 1:1 to 1:5 [oxalic acid: ammonium chloride].

[0048] The present invention comprises the step of (c) adding a base to the lithium-containing filtrate to precipitate iron hydroxide (Fe(OH)3) and aluminum hydroxide (Al(OH)3).

[0049] The lithium-containing filtrate obtained through step (b) above contains a significant amount of lithium, but also contains residual impurities. Therefore, a process to remove residual impurities is required. The residual impurities present in the lithium-containing filtrate are preferably Fe 3+ and Al 3+ Includes

[0050] Fe 3+ and Al 3+ To remove the lithium, a base may be added to the lithium-containing filtrate. The base is preferably a weak base, and more preferably ammonium hydroxide (NH4OH), but is not limited thereto.

[0051] When ammonium hydroxide is used, impurities capable of forming metal hydroxides, such as iron and aluminum, can be removed from the lithium-containing filtrate, and at the same time, the pH of the lithium-containing filtrate can be increased. This increases the recovery efficiency of lithium chloride. In addition, when ammonium hydroxide is used as a base, there is an advantage that removing ammonium chloride (NH4Cl) coexisting in the lithium chloride solution is relatively easier than removing other chlorides (e.g., sodium chloride). Furthermore, there is an advantage that the added value of the ammonium chloride produced in this separation process is greater than that of other chlorides (e.g., sodium chloride).

[0052] When adding a base to a lithium-containing filtrate, controlling the pH is very important. It is preferable that the pH of the lithium-containing filtrate to which the base has been added be 1 to 9.5, and ultimately, it is preferable to add the base so that the pH of the lithium-containing filtrate reaches 8 to 9.

[0053] By adding a base, Fe contained in the lithium-containing filtrate 3+ and Al 3+ It can be precipitated as iron hydroxide (Fe(OH)3) and aluminum hydroxide (Al(OH)3). The precipitated iron hydroxide and aluminum hydroxide can be separated by filtering the lithium-containing filtrate. Li + For filtration of the leachate, filter paper may be used, and preferably, filter paper with a pore size of 5 μm or less may be used.

[0054] After filtration, iron hydroxide and aluminum hydroxide separated from the lithium-containing filtrate are removed. Once the iron hydroxide and aluminum hydroxide are removed, the solution is prepared for a concentration process to recover the lithium chloride (LiCl) solution.

[0055] The present invention includes (d) a step of recovering a lithium chloride (LiCl) solution.

[0056] The recovered lithium chloride solution includes the following first solution, and preferably includes the following first solution and second solution.

[0057] The first solution is a solution obtained by removing iron hydroxide and aluminum hydroxide precipitates from the lithium-containing filtrate in step (c).

[0058] Since lithium remains in the iron hydroxide and aluminum hydroxide removed during the process of obtaining the first solution, the remaining lithium can be recovered from them. The second solution is a solution obtained by washing the removed iron hydroxide and aluminum hydroxide with deionized water.

[0059] Examples

[0060] The present invention will be explained in more detail below by way of examples, but the present invention is not limited by these examples.

[0061] (Composition of Black Mass)

[0062] Table 1 shows the results of three repeated analyses of the black mass obtained from the NCM battery using ICP-OES.

[0063] Content (wt%) Li Ni Co Mn Cu Al Fe Ca Zn Na Analysis 1 3.38 22.09 2.29 1.12 2.34 3.13 4.94 0.33 0.18 2.10 Analysis 2 3.18 21.43 2.23 1.05 2.14 3.02 4.66 0.33 0.13 1.41 Analysis 3 3.20 19.02 2.07 0.97 1.99 2.79 4.34 0.25 0.11 1.05 average 3.25 20.84 2.19 1.04 2.15 2.98 4.64 0.30 0.14 1.52

[0064] (Preparation of oxalic acid-choline chloride deep eutectic solvent)

[0065] 37.8 g of oxalic acid was doped with choline chloride such that the molar ratio of oxalic acid to choline chloride was 30:0.1, 30:0.2, 30:1, and 30:10, respectively, and heated at a temperature of 60 to 80 °C for 1 hour. After heating, deionized water was added to each solution to make the volume 100 mL, thereby preparing deep eutectic solvents of oxalic acid-choline chloride with molar ratios of oxalic acid to choline chloride of 30:0.1, 30:0.2, 30:1, and 30:10, respectively.

[0066] <Test Example 1. Leaching Efficiency Test According to Molar Ratio of Oxalic Acid and Choline Chloride>

[0067] (Example 1-1)

[0068] In a reactor, black mass obtained from an NCM battery (a new sample other than the black mass in Table 1 above) and an oxalic acid-choline chloride deep eutectic solvent having an oxalic acid-choline chloride molar ratio of 30:0.1 were mixed, and heating and stirring were performed at 50 to 95 °C for 0.5 to 3 hours to Li + A leachate was obtained. The obtained Li + The content of Li, Ni, Mn, Co, Cu, and Al in the leaching solution and the remaining NCM cake is shown in Table 2.

[0069] (Examples 1-2 to 1-4)

[0070] In Example 1-1, Li obtained by varying only the molar ratio of oxalic acid to choline chloride + The content (wt%) of Li, Ni, Mn, Co, Cu, and Al in the leaching solution is shown in Table 2.

[0071] Molby [Oxalic acid:choline chloride] Li Ni Mn Co Cu Al Black mass before leaching 3.62 16.57 5.10 5.27 3.60 1.32 Example 1-1 30:0.1 Li + leachate 2.39 0.01 0.20 0.01 0.04 0.30 NCM Cake 1.17 15.51 4.69 5.31 3.53 0.94 total 3.56 15.52 4.89 5.32 3.57 1.24 Examples 1-2 30:0.2 Li + leachate 3.25 0.01 0.30 0.01 0.11 0.32 NCM Cake 0.35 15.90 5.44 5.44 3.45 1.01 total 3.60 15.91 5.45 5.45 3.56 1.33 Examples 1-3 30:1 Li + leachate 3.43 0.00 0.17 0.01 0.10 0.31 NCM Cake 0.18 16.06 4.89 5.48 3.49 1.01 total 3.61 16.06 5.26 5.49 3.59 1.32 Examples 1-4 30:10 Li + leachate 3.57 0.50 0.60 0.01 2.33 0.40 NCM Cake 0.12 15.92 4.10 5.20 1.30 1.11 total 3.69 16.42 4.70 5.21 3.63 1.51

[0072] The core of the present invention is to selectively leach lithium and minimize the content of other metals, particularly copper, in the leaching solution. Among the above examples, Examples 1-3 and 1-4 showed excellent lithium leaching efficiency. However, in Examples 1-4, the copper content in the leaching solution was relatively high at 2.33 wt%, so it was not suitable as an optimal condition for lithium leaching. Therefore, an oxalic acid-choline chloride deep eutectic solvent with a molar ratio of oxalic acid to choline chloride of 30:1 was selected as the optimal condition.

[0073] <Test Example 2. Secondary Leaching Test>

[0074] (1st leaching process)

[0075] In a reactor, 25 g of NCM black mass and 100 mL of a deep eutectic solvent of oxalic acid-choline chloride in a 30:1 molar ratio were mixed, and heating and stirring were carried out at 90 °C for 3 hours to Li + The first extract was obtained.

[0076] (Secondary leaching process)

[0077] 25 g of NCM black mass was added to the reactor, and the Li obtained from the first leaching process was added. + A 150 mL mixed solution was used as the leaching solvent, comprising 100 mL of the extract and 50 mL, which is half the volume of the oxalic acid-choline chloride deep eutectic solvent with a 30:1 molar ratio used in the first leaching process. Heating and stirring were performed at 90 ℃ for 3 hours, and Li + A second leachate was obtained.

[0078] Li obtained through the primary leaching process + The concentration (ppm) of 100 mL of the first extract and the total Li obtained after the second leaching process + The concentrations (ppm) of lithium, iron, and aluminum in 150 mL of the leaching solution are shown in Table 4.

[0079] Li + Concentration of 100 mL of primary extract Total Li after secondary leaching + Concentration of 150 mL of extract Li 7,875 10,383 Fe 10,825 14,316 Al 7,125 9,383

[0080] <Test Example 3. Chloride Conversion Test>

[0081] 24.07 g of ammonium chloride was added to 150 mL of the total leaching solution obtained in Test Example 2, and the solid precipitate was removed to obtain a lithium-containing filtrate. The concentrations (ppm) of lithium, iron, and aluminum in the obtained lithium-containing filtrate are shown in Table 4.

[0082] Concentration before addition of ammonium chloride (Oxalate) Concentration after addition of ammonium chloride (chloride) Conversion rate (%) Li 10,383 10,246 98.68 Fe 14,316 14,096 98.46 Al 9,383 9,232 98.39

[0083] By adding ammonium chloride, lithium, iron, and aluminum ions present in the form of oxalates were almost entirely converted into chlorides.

[0084] <Test Example 4. Fe 3+ , Al 3+ Selective Removal Test〉

[0085] 23.37 mL of ammonium hydroxide is added to 150 mL of the lithium-containing filtrate obtained in Test Example 3. The concentrations (ppm) of lithium, iron, and aluminum in the lithium chloride solution obtained by removing solid precipitates (iron hydroxide and aluminum hydroxide) and the lithium recovery rate are shown in Table 5.

[0086] Concentration before sediment removal Concentration after precipitate removal Selectivity (%) Lithium recovery rate (%) Li 10,246 9,780 95.45 90.27 Fe 14,096 32 0.22 N / A Al 9,232 41 0.44 N / A

[0087] By this method, lithium was recovered to a high level, and iron and aluminum were selectively removed.

Claims

Claim 1 As a method for recycling lithium from a lithium-ion battery, (a) to black mass obtained from a lithium-ion battery, an oxalic acid-choline chloride deep eutectic solvent having a molar ratio of oxalic acid to choline chloride of 30:0.1 to 30:10 is added to Li + Step of obtaining a leachate; (b) the Li + A method for recycling lithium from a lithium-ion battery, comprising the steps of: (a) adding ammonium chloride (NH4Cl) to a leachate and removing a solid precipitate to obtain a lithium-containing filtrate; (c) adding a base to the lithium-containing filtrate to precipitate iron hydroxide (Fe(OH)3) and aluminum hydroxide (Al(OH)3); and (d) recovering a lithium chloride (LiCl) solution, wherein the lithium-ion battery is an LCO (Lithium Cobalt Oxide), LMO (Lithium Manganese Oxide), NCM (Nickel Cobalt Manganese), NCMA (Nickel Cobalt Manganese Aluminum), or NCA (Nickel Cobalt Aluminum) battery. Claim 2 In claim 1, the Li in step (a) + A method for recycling lithium from a lithium-ion battery, wherein the concentration of copper in the leaching solution is 2.33 wt% or less. Claim 3 A method for recycling lithium from a lithium-ion battery according to claim 1, wherein the oxalic acid-choline chloride deep eutectic solvent in step (a) functions as a reducing agent and a leaching agent. Claim 4 A method for recycling lithium from a lithium-ion battery according to claim 1, wherein the ammonium chloride in step (b) is added in a molar ratio of 1:1 to 1:5 [oxalic acid: ammonium chloride]. Claim 5 A method for recycling lithium from a lithium-ion battery, wherein, in claim 1, the base in step (c) is ammonium hydroxide (NH4OH). Claim 6 A method for recycling lithium from a lithium-ion battery according to claim 1, wherein step (d) comprises the step of obtaining a first solution by removing iron hydroxide and aluminum hydroxide precipitates from a lithium-containing filtrate, and the step of obtaining a second solution by washing the removed iron hydroxide and aluminum hydroxide with deionized water. Claim 7 A method for recycling lithium from a lithium-ion battery according to claim 6, wherein, in the step of removing iron hydroxide and aluminum hydroxide precipitates from a lithium-containing filtrate to obtain a first solution, a filter paper having a pore size of 5 μm or less is used. Claim 8 delete Claim 9 delete

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