Eco-friendly and high efficiently method for manufacturing lithium compound from waste cathode material

Abstract

The present invention relates to a method for producing a lithium compound with high efficiency in an eco-friendly manner from waste lithium batteries and waste cathode materials contained in waste scrap and slurries generated during the process, comprising: (a) ultrasonically treating the waste cathode material in a base solution containing chlorine or fluorine to form a lithium compound solution containing chlorine or fluorine; (b) filtering the lithium compound solution to remove impurities; and (c) evaporating the liquid component of the lithium compound solution to obtain a solid lithium compound containing chlorine or fluorine. The lithium recovery method according to the present invention can form a lithium compound from waste cathode materials with a high recovery rate through a simple and eco-friendly process.

Description

Technology Field

[0001] The present invention relates to a method for recovering lithium from waste lithium batteries and waste cathode materials contained in waste scrap and slurries generated during the process.

[0002] More specifically, the present invention relates to a method for producing lithium compounds in the form of lithium chloride and lithium fluoride from waste cathode materials through an economical and environmentally friendly process without processes such as strong acid treatment or high-temperature heat treatment. Background Technology

[0004] With the advancement of various mobile devices such as smartphones, tablets, and laptops, mobility devices like electric vehicles, drones, and electric aircraft, and various energy storage systems (ESS), the demand for lithium batteries, such as lithium-ion batteries, is also increasing. Along with this, the usage of precious metals for the cathode materials of lithium batteries is also on the rise.

[0005] As the use of lithium batteries increases, the amount of waste lithium batteries and waste cathode materials contained in waste scrap and slurries generated during the lithium battery manufacturing process is increasing day by day. Such waste cathode materials contain about 5-7 weight percent of lithium. Therefore, much research is being conducted on methods to recover lithium compounds from waste cathode materials.

[0006] Conventional lithium recovery methods include a method of recovering lithium by leaching lithium and manganese-containing cathode materials from waste lithium batteries using strong acids such as nitric acid, sulfuric acid, and hydrochloric acid, followed by a neutralization reaction (e.g., Patent Document 1). However, the above recovery method is criticized for being uneconomical because it causes environmental problems due to the use of acid, requires the use of expensive chemicals, and requires multiple washing processes because a large amount of intermediate products are generated during the process and act as impurities.

[0007] Another conventional method for recovering lithium involves using high-temperature heat treatment to chemically react waste cathode material with carbon dioxide to recover lithium in the form of lithium carbonate (e.g., Patent Document 2). However, the high-temperature heat treatment method requires high-temperature heat treatment equipment, and the introduction of gas leads to increased manufacturing costs and environmental problems such as carbon emissions. Furthermore, it is inefficient due to high power consumption and has the problem of increased maintenance costs due to equipment damage.

[0008] Therefore, there is a need for a method to recover lithium economically and environmentally from waste cathode materials, such as waste lithium secondary battery cathode material powder and process slurry cathode material, with a high recovery rate and a simple process. Prior art literature

[0010] Registered Patent Publication No. 10-1823952 (Published Jan. 31, 2018) Registered Patent Publication No. 10-2420751 (Published July 15, 2022) The problem to be solved

[0011] The problem that the present invention aims to solve is to provide a method for producing lithium compounds such as lithium chloride and lithium fluoride economically and environmentally through a simple process from waste lithium batteries and waste cathode materials contained in waste scrap and slurries generated during the entire manufacturing process. means of solving the problem

[0013] To achieve the above technical objectives, the method for manufacturing an eco-friendly high-efficiency lithium compound according to the present invention comprises: (a) ultrasonically treating a waste cathode material in a base solution containing chlorine or fluorine to form a lithium compound solution containing chlorine or fluorine; (b) filtering the lithium compound solution to remove impurities; and (c) evaporating the liquid component of the lithium compound solution to obtain a solid lithium compound containing chlorine or fluorine.

[0014] Prior to step (a) above, a step of pre-extracting valuable metal components other than lithium from the waste cathode material may be further included.

[0015] After step (c) above, a step of crystallizing a solid lithium compound may be further included.

[0016] Preferably, the base solution may be hydrochloric acid or hydrofluoric acid dissolved in water.

[0017] Preferably, in step (a), the ultrasonic treatment can be performed with an output of 300 W or more.

[0018] Preferably, in step (a), the ultrasonic treatment can be performed at a temperature of 25 to 90°C.

[0019] Preferably, in step (a), the ultrasonic treatment can be performed under stirring.

[0020] Preferably, the lithium compound obtained in step (c) may include lithium chloride (LiCl) or lithium fluoride (LiF). Effects of the invention

[0022] The method for manufacturing an eco-friendly, high-efficiency lithium compound according to the present invention allows for the recovery of a lithium compound economically, eco-friendlyly, and with high efficiency through a simple process by ultrasonically treating waste cathode material in an aqueous solution to induce the lithium (Li) element to react with components such as chlorine and fluorine in the aqueous solution to produce a lithium compound containing chlorine or fluorine.

[0023] In particular, by simplifying the process using the reaction between ultrasound and an aqueous solution, it offers high economic efficiency and productivity in reducing material costs, and is environmentally friendly compared to conventional strong acid and high-temperature heat treatment processes.

[0024] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below. Brief explanation of the drawing

[0026] FIG. 1 is a flowchart schematically illustrating a method for manufacturing an eco-friendly, high-efficiency lithium compound from waste cathode material according to the present invention. Specific details for implementing the invention

[0027] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described in detail below. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0028] The following describes in detail a method for manufacturing an eco-friendly, high-efficiency lithium compound from waste cathode materials according to a preferred embodiment of the present invention.

[0030] FIG. 1 is a flowchart schematically illustrating a method for manufacturing an eco-friendly, high-efficiency lithium compound from waste cathode material according to the present invention.

[0031] Referring to FIG. 1, the method for manufacturing an eco-friendly high-efficiency lithium compound according to the present invention includes an ultrasonic treatment step (S110), a filtration step (S120), and an evaporation step (S130).

[0032] First, in the ultrasonic treatment step (S110), the waste cathode material is ultrasonically treated in a base solution containing chlorine or fluorine to form a lithium compound solution. Prior to the ultrasonic treatment, valuable metal components other than lithium, such as manganese (Mn), cobalt (Co), and nickel (Ni), can be pre-extracted from the waste cathode material. Pre-extraction of valuable metal components can be performed using conventional methods used in the relevant technical field; for example, valuable metals other than lithium can be leached using strong acids such as sulfuric acid, hydrochloric acid, or nitric acid, and then extracted and separated using chemicals. When applying pre-extraction of valuable metals, the lithium recovery rate can be further increased, and the process can also be performed efficiently.

[0033] In the ultrasonic treatment step (S110), the base solution may be an aqueous solution containing chlorine or fluorine. An aqueous solution is a solution in which a salt or acid is dissolved in water; in the present invention, the aqueous solution may preferably be a solution in which hydrochloric acid or hydrofluoric acid is dissolved in water. If the aqueous solution contains a hydrochloric acid component, lithium chloride may be produced. If the aqueous solution contains a hydrofluoric acid component, lithium fluoride may be produced.

[0034] When the aqueous solution contains hydrochloric acid or hydrofluoric acid components, since the products are lithium chloride or lithium fluoride, respectively, the resulting lithium compounds can be directly applied as raw materials for electrolyte manufacturing or for other uses without a separate reprocessing process.

[0035] In the ultrasonic treatment step (S110), first, ultrasonic equipment and a base solution are prepared, and after the waste cathode material is introduced into the base solution, ultrasound is applied. By utilizing the ultrasonic energy resulting from the application of ultrasound, the reactivity between the base solution and lithium can be increased, thereby producing an aqueous solution of a lithium compound.

[0036] The waste cathode material subject to lithium recovery is waste lithium battery or waste cathode material contained in waste scrap and slurry generated in the battery manufacturing process. It is preferable that the waste cathode material introduced into the base solution be in the form of powder obtained through a crushing process. The waste cathode material powder may be manufactured using one or more of lithium hydroxide and lithium carbonate as raw materials.

[0037] The concentration of hydrochloric acid or hydrofluoric acid in the base solution may be 0.1 to 5.0 M, but is not limited thereto. If the concentration of hydrochloric acid or hydrofluoric acid in the base solution is within the above range, the recovery rate of the lithium compound can be increased.

[0038] The base solution may be used in a ratio of 1 to 50 L per 1 kg of waste cathode material, but is not limited thereto. If the base solution is used within the above ratio range, the recovery rate of the lithium compound can be increased.

[0040] After the waste cathode material is introduced into the base solution within the ultrasonic equipment, it can be uniformly distributed within the base solution through stirring.

[0041] Ultrasonically treating waste cathode materials in a base solution significantly increases the efficiency of lithium compound formation compared to cases where this is not done, ultimately leading to a substantial increase in the lithium recovery rate. This can be attributed to the fact that the lithium (Li) elements present in the waste cathode materials react with components in the aqueous solution, inducing the formation of lithium compounds, due to the ultrasonic energy applied during the treatment. Furthermore, lithium elements react readily with aqueous solutions. Accordingly, high-purity lithium compound solutions containing chlorine or fluorine can be produced through ultrasonic treatment.

[0042] The ultrasonic output of the ultrasonic equipment can be adjusted according to the state and quantity of the raw material. To increase the reactivity of the lithium compound with respect to the base solution, it is desirable to perform the ultrasonic treatment at an output of 300 W or higher. If the ultrasonic treatment is performed at an output of less than 300 W, the recovery rate of the lithium compound may be lower. Although an upper limit for the ultrasonic treatment output is not separately determined, it may be performed at an output of approximately 4000 W or less.

[0044] In addition, ultrasonic treatment can be performed at a temperature of 25°C or higher, for example, 25 to 90°C, preferably 30 to 60°C. More preferably, ultrasonic treatment can be performed at a temperature of 40 to 60°C to improve the lithium recovery rate. If ultrasonic treatment is performed at a temperature below 25°C, the recovery rate of the lithium compound may be low. It is preferable that ultrasonic treatment be performed at a temperature of 90°C or lower. If performed at a temperature above 90°C, by-products may be generated or the amount of water evaporation may increase.

[0045] Ultrasonic treatment can be performed for more than 1 minute, for example, from 2 minutes to 1 hour. When the ultrasonic treatment time range is as described above, the recovery rate of the lithium compound is excellent.

[0046] In addition, it is preferable that the ultrasonic treatment be performed under stirring. If the ultrasonic treatment is performed under stirring, the recovery rate of the lithium compound can be increased. Conventional stirring methods used in the relevant technical field may be utilized.

[0048] Next, in the filtration step (S120), the lithium compound solution is filtered to remove impurities. The impurities include solid impurities such as solid precipitates or sludge. The solid precipitates may be filtered after the sludge is removed first. Additionally, the impurities may include metals other than lithium dissolved in the lithium compound solution. Various known filtration methods may be used, such as filtration using mechanical devices like solid-liquid separation devices or filter presses, or filtration of metals other than lithium using chemical extraction.

[0050] After filtration, the process may include concentrating the lithium compound solution from which impurities have been removed.

[0052] Next, in the evaporation step (S130), the liquid component of the lithium compound solution is evaporated to obtain a solid lithium compound containing chlorine or fluorine. The liquid component can be the solvent component of the base solution. If the base solution is an aqueous solution, the liquid component can be water. To evaporate the water component, the lithium compound solution can be heated to a temperature of approximately 100°C, which is close to the boiling point of water.

[0053] The obtained lithium compound may include lithium chloride (LiCl) or lithium fluoride (LiF). The obtained lithium compound is determined by the components included in the base solution.

[0054] The obtained lithium compound may be in a crystalline or amorphous form. If necessary, a process for crystallizing the solid lithium compound may be further performed. Crystallization may be carried out by conventional methods used in the relevant technical field, depending on the type of lithium compound.

[0056] The method for recovering lithium from waste cathode material powder according to the present invention can recover lithium in the form of a lithium compound in an economical, eco-friendly, and high-efficiency manner through ultrasonic treatment, filtration, and evaporation processes.

[0058] The present invention will be explained more specifically below through examples, comparative examples, and experimental examples. These examples, comparative examples, and experimental examples are intended solely to illustrate the present invention, and it is obvious to those skilled in the art that the scope of the present invention is not limited thereto.

[0060] 1. Lithium recovery

[0061] As the waste cathode material subject to lithium recovery, cathode material powder from waste batteries using lithium hydroxide or lithium carbonate as a raw material was used.

[0062] (1) Example 1

[0063] 5 kg of waste cathode material powder was introduced into a reactor filled with a 1.0 M aqueous hydrochloric acid solution as a base solution and reacted by ultrasonizing at 50°C for 10 minutes with an output of 3000 W.

[0064] The above reaction mixture was filtered to obtain a solution, and the solution was heated to 100°C to evaporate the water to obtain a lithium compound.

[0066] (2) Example 2

[0067] A lithium compound was obtained in the same manner as in Example 1, except that a 1.0 M aqueous hydrofluoric acid solution was used as the base solution.

[0069] (3) Example 3

[0070] 5 kg of waste cathode material powder was pre-extracted of valuable metals other than lithium, placed in a reactor filled with a 1.0 M aqueous hydrochloric acid solution, and reacted by ultrasonizing at 50°C for 1 hour under stirring with an output of 500 W.

[0071] The reactants were filtered to obtain a solution, and the solution was heated to 100°C to evaporate the water to obtain a lithium compound.

[0073] (4) Comparative Example 1

[0074] A lithium compound was obtained in the same manner as in Example 1, except that ultrasonic treatment was not performed.

[0076] (5) Comparative Example 2

[0077] A lithium compound was obtained in the same manner as in Example 2 above, except that ultrasonic treatment was not performed.

[0079] (6) Comparative Example 3

[0080] A lithium compound was obtained in the same manner as in Example 1 above, except that water was used instead of a 1.0 M aqueous hydrochloric acid solution as the base solution.

[0082] 2. Characteristic Evaluation Method

[0083] The lithium recovery rate was calculated using the following mathematical formula 1.

[0084] [Mathematical Formula 1]

[0085] Recovery rate (%) = (Amount of recovered Li (g)) / (Amount of initial Li (g)) × 100

[0086] Here, the initial amount of lithium was measured through ICP (Inductively Coupled Plasma) analysis.

[0087] The amount of recovered Li was calculated stoichiometrically from the amount of lithium compounds obtained in Examples 1-3 and Comparative Examples 1-3.

[0089] 3. Characteristic Evaluation Results

[0090] The results of calculating the lithium recovery rate of the method according to Examples 1-3 and Comparative Examples 1-3 are shown in Table 1.

[0091] [Table 1]

[0092]

[0093] As shown in Table 1 above, it can be confirmed that Examples 1 to 3, in which waste cathode material powder was reacted by ultrasonically treating it in an aqueous solution containing chlorine or fluorine according to the method of the present invention, showed a significantly superior lithium recovery rate compared to Comparative Examples 1 to 2, in which the reaction was carried out without ultrasonically treating.

[0094] In addition, the cases of Examples 1 to 3 showed a higher recovery rate compared to Comparative Example 1, which used water instead of the aqueous solution containing chlorine or fluorine used in the present invention.

[0095] In addition, when comparing Example 1 and Example 3, it was found that the recovery rate was improved in the case of Example 3, in which ultrasonic treatment was performed while stirring.

[0097] As specific parts of the present invention have been described in detail above, it is evident to those skilled in the art that such specific descriptions are merely preferred embodiments and do not limit the scope of the present invention. Those skilled in the art will be able to make various applications and modifications within the scope of the present invention based on the above description.

Claims

Claim 1 (a) a step of ultrasonically treating waste cathode material in a base solution in which hydrofluoric acid is dissolved in water with an output of 300 W or more to form a lithium compound solution containing fluorine; (b) a step of filtering the lithium compound solution to remove impurities; and (c) a step of evaporating the liquid component of the lithium compound solution to obtain a solid lithium compound containing fluorine, comprising an eco-friendly high-efficiency lithium compound manufacturing method. Claim 2 A method for manufacturing an eco-friendly, high-efficiency lithium compound according to claim 1, further comprising, prior to step (a), a step of pre-extracting valuable metal components other than lithium from the waste cathode material. Claim 3 A method for manufacturing an eco-friendly, high-efficiency lithium compound according to claim 1, further comprising, after step (c), a step of crystallizing a solid lithium compound. Claim 4 A method for manufacturing an eco-friendly, high-efficiency lithium compound according to claim 1, wherein in step (a), the ultrasonic treatment is performed at a temperature of 25 to 90°C. Claim 5 A method for manufacturing an eco-friendly, high-efficiency lithium compound according to claim 1, wherein in step (a), the ultrasonic treatment is performed under stirring. Claim 6 A method for manufacturing an environmentally friendly, high-efficiency lithium compound according to claim 1, wherein the lithium compound obtained in step (c) comprises lithium fluoride (LiF). Claim 7 delete Claim 8 delete

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