EP-4742364-A1 - METHOD FOR RECOVERING LITHIUM COMPOUND FROM CATHODE MATERIAL OF LITHIUM-ION BATTERY

EP4742364A1EP 4742364 A1EP4742364 A1EP 4742364A1EP-4742364-A1

Abstract

The present invention relates to a method of recovering a lithium compound. According to the present invention, the method of the present invention includes step (a) of extracting a reduced roasted product of a lithium-ion battery cathode material using an organic solvent containing a cation exchange extractant to obtain a lithium-extracted organic solvent and extraction residues; step (b) of separating the lithium-extracted organic solvent and the extraction residues; step (c) of stripping the separated lithium-extracted organic solvent using an acidic solution to obtain a lithium-containing aqueous solution and an organic solvent; step (d) of separating the lithium-containing aqueous solution and the organic solvent; and step (e) of carbonating lithium in the separated lithium-containing aqueous solution to obtain lithium carbonate. According to the present invention, the present invention relates to a method of recovering a lithium compound from a lithium-ion battery cathode material. According to the method of the present invention, by directly extracting lithium from a reduced roasted product of a lithium-ion battery cathode material using an organic solvent containing a cation exchange extractant, and subsequently performing stripping using an acidic solution, the lithium recovery rate may be increased, the energy, time, and cost required for recovering lithium may be reduced. Accordingly, economic feasibility and efficiency may be improved.

Inventors

LEE, DONGSEOK
KWON, OHSUNG
YU, Hyemin
KIM, Donghyeon
NOH, Taechong
LEE, Jeongbae

Assignees

LG Energy Solution, Ltd.

Dates

Publication Date: 20260513
Application Date: 20250701

Claims (20)

A method of recovering a lithium compound, comprising: (a) extracting a reduced roasted product of a lithium-ion battery cathode material using an organic solvent containing a cation exchange extractant to obtain a lithium-extracted organic solvent and extraction residues; (b) separating the lithium-extracted organic solvent and the extraction residues; (c) stripping the separated lithium-extracted organic solvent using an acidic solution to obtain a lithium-containing aqueous solution and an organic solvent; (d) separating the lithium-containing aqueous solution and the organic solvent; and (e) carbonating lithium in the separated lithium-containing aqueous solution to obtain lithium carbonate.
The method according to claim 1, wherein, in step (a), the reduced roasted product of the lithium-ion battery cathode material is obtained by mixing the lithium-ion battery cathode material with a carbon-containing reducing agent, roasting the mixture at 550 to 750 °C, and then pulverizing the roasted mixture.
The method according to claim 2, wherein the carbon-containing reducing agent is used in an amount of 0 to 3 mol per 1 mol of a cathode active material in the lithium-ion battery cathode material.
The method according to claim 2, wherein the carbon-containing reducing agent is an organic substance containing carbon, an inorganic substance containing carbon, an anode material, or a mixture thereof.
The method according to claim 2, wherein the roasting is performed under a reducing gas or an inert gas.
The method according to claim 2, wherein the lithium-ion battery cathode material comprises one or more selected from the group consisting of lithium cobalt oxide; lithium manganese oxide; a lithium iron phosphate compound; lithium nickel cobalt aluminum oxide; lithium nickel oxide; a nickel-manganese-based lithium composite metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn); and an NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co).
The method according to claim 2, wherein the lithium-ion battery cathode material is a waste lithium-ion battery cathode material.
The method according to claim 2, wherein the pulverizing is performed using a milling machine.
The method according to claim 1, wherein, in step (a), the cation exchange extractant comprises an alkyl phosphate-based extractant, alkyl monocarboxylic acid, or a mixture thereof.
The method according to claim 9, wherein the alkyl phosphate-based extractant comprises one or more selected from the group consisting of di-(2-ethylhexyl) phosphate, 2-ethylhexyl hydrogen-2-ethylhexylphosphonate, and bis(2,4,4-trimethylpentyl)phosphinic acid.
The method according to claim 9, wherein the alkyl monocarboxylic acid comprises a compound represented by Chemical Formula 1 below. wherein R 1 and R 2 are each independently an alkyl group, and the total number of carbon atoms in R 1 and R 2 is from 5 to 9.
The method according to claim 1, wherein, in step (a), the organic solvent comprises one or more selected from the group consisting of kerosene, hexane, benzene, and toluene.
The method according to claim 1, wherein, in step (a), the cation exchange extractant is comprised in an amount of 0.9 to 2.5 mol per 1 mol of lithium in the reduced roasted product of the lithium-ion battery cathode material.
The method according to claim 1, wherein, in step (a), a solid-to-liquid ratio of the reduced roasted product of the lithium-ion battery cathode material to the organic solvent containing a cation exchange extractant is 1 g/8 ml to 1 g/44 ml.
The method according to claim 1, wherein, in step (b), separation of the lithium-extracted organic solvent and the extraction residues is performed using vacuum filtration.
The method according to claim 1, wherein, in step (c), an organic/aqueous volume ratio of the lithium-extracted organic solvent to the acidic solution is 0.5 to 10.
The method according to claim 1, wherein, in step (c), the acidic solution is a sulfuric acid aqueous solution, a hydrochloric acid aqueous solution, or a nitric acid aqueous solution.
The method according to claim 1, wherein, in step (e), the carbonation is performed by adding carbonate or carbon dioxide gas.
The method according to claim 1, wherein, in step (d), the separated organic solvent is reused in the extraction of step (a).
The method according to claim 1, further comprising leaching the extraction residues obtained in step (b) with an acid to obtain a leachate containing dissolved residual metal compounds.

Description

[Technical Field] [Cross-Reference to Related Application] This application claims priority to Korean Patent Application No. 10-2024-0088106, filed on July 4, 2024, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. The present invention relates to a method of recovering a lithium compound from a lithium-ion battery cathode material. More particularly, according to the method of the present invention, by directly extracting lithium from a reduced roasted product of a lithium-ion battery cathode material using an organic solvent containing a cation exchange extractant, and subsequently performing stripping using an acidic solution, the lithium recovery rate may be increased, and the energy, time, and cost required for concentration to recover lithium may be reduced. Accordingly, economic feasibility and efficiency may be improved. [Background Art] Demand for lithium-ion batteries has been steadily increasing along with the portable electronic device market since the 1990s, and has recently been increasing further worldwide due to the rapid expansion of the electric vehicle market. This trend could lead to instability in the supply and demand of lithium resources in the near future, and the continuous accumulation of waste batteries could cause major environmental problems. To solve these problems, recycling of used lithium-ion batteries is a very important technological challenge. A lithium-ion battery is largely composed of a cathode formed by coating a metal foil such as aluminum with a cathode active material layer, an anode formed by coating a metal foil such as copper with an anode active material layer, a separator that prevents the cathode and anode from mixing, and an electrolyte solution that allows lithium ions to move between the cathode and anode. A cathode accounts for more than 60 % of the cost of a lithium-ion battery. Lithium cobalt oxide (LiCoO2) is used as the cathode because the lithium cobalt oxide has excellent reversibility, low self-discharge rate, high capacity, and high energy density, and is easy to synthesize. In addition, to reduce the use of expensive cobalt, lithium complex oxides containing Ni, Mn, and the like, such as lithium nickel cobalt manganese oxide (Li(Ni, Co, Mn)O2), lithium manganese oxide (LiMnO2), and lithium iron phosphate (LiFePO4), are used. Since the cathode material contains about 5 to 7 % lithium, a method of recovering lithium compounds from cathode materials of waste lithium-ion batteries is receiving significant attention. A conventional method for recovering lithium compounds from waste lithium-ion battery cathode material involves converting lithium from waste lithium-ion battery cathode material into lithium carbonate through reduction heat treatment using carbon, followed by water leaching. Although this process allows selective recovery of lithium, it has problems of low lithium recovery rates and significant consumption of energy, cost, and time during processes such as evaporation concentration, vacuum concentration, or electrochemical concentration to concentrate the lithium carbonate. Therefore, there is a need to develop a method for recovering lithium compounds from waste lithium-ion battery cathode material, which improves the recovery rate of lithium compounds and reduces the energy, cost, and time required for lithium concentration. [Related Art Documents] [Patent Documents] KR 2015-0094412 A [Disclosure] [Technical Problem] Therefore, the present invention has been made in view of the above problems, and it is one object of the present invention to provide a method of recovering a lithium compound from a lithium-ion battery cathode material. According to the method of the present invention, by directly extracting lithium from a reduced roasted product of a lithium-ion battery cathode material using an organic solvent containing a cation exchange extractant, and subsequently performing stripping using an acidic solution, the lithium recovery rate may be increased, and the energy, time, and cost required for lithium concentration may be reduced. Accordingly, economic feasibility and efficiency may be improved. It is another object of the present invention to provide a high-purity lithium compound. The above and other objects can be accomplished by the present invention described below. [Technical Solution] I) In accordance with one aspect of the present invention, provided is a method of recovering a lithium compound, the method including (a) extracting a reduced roasted product of a lithium-ion battery cathode material using an organic solvent containing a cation exchange extractant to obtain a lithium-extracted organic solvent and extraction residues; (b) separating the lithium-extracted organic solvent and the extraction residues; (c) stripping the separated lithium-extracted organic solvent using an acidic solution to obtain a lithium-containing aqueous solution and an organic solvent;