KR-102962517-B1 - ELECTROCHEMICAL LITHIUM RECOVERY SYSTEM WITH IMPROVED LITHIUM EXTRACTION EFFICIENCY FROM WASTE BATTERIES

KR102962517B1KR 102962517 B1KR102962517 B1KR 102962517B1KR-102962517-B1

Abstract

The present invention relates to an electrochemical lithium recovery system that improves the efficiency of lithium extraction from waste batteries. The lithium recovery system comprises an electrolytic cell and an electrolyte membrane that partitions the interior of the electrolytic cell to separate it into an extraction tank filled with an extraction solution for extracting lithium and a recovery tank filled with a recovery solution for recovering lithium. The lithium recovery system is characterized by comprising: a first electrode immersed in the extraction solution; a second electrode electrically connected to the first electrode, immersed in the extraction solution, and having a porous structure; and a third electrode electrically connected to the second electrode and immersed in the recovery solution.

Inventors

김영식
김하은
김월영

Assignees

울산과학기술원
(주)솔라라이트

Dates

Publication Date: 20260511
Application Date: 20230516

Claims (13)

A lithium recovery system comprising an electrolytic cell and an electrolyte membrane that partitions the interior of the electrolytic cell to separate it into an extraction tank filled with an extraction solution for extracting lithium and a recovery tank filled with a recovery solution for recovering lithium, wherein A first electrode immersed in the above extraction solution; A second electrode electrically connected to the first electrode and immersed in the extraction solution, having a porous structure; and A lithium recovery system characterized by including a third electrode electrically connected to the second electrode and immersed in the recovery solution.
In Article 1, The current collector of the second electrode above is, A metal current collector selected from the group consisting of nickel mesh (Ni mesh), titanium mesh (Ti mesh), stainless steel mesh (SS mesh) and aluminum mesh (Al mesh), Lithium recovery system.
In Article 1, The above lithium recovery system further includes a first power supply unit that applies current between the first electrode and the second electrode, and Characterized that when current is applied to the first electrode and the second electrode through the first power supply unit, an electrochemical oxidation reaction occurs at the first electrode and an electrochemical reduction reaction occurs at the second electrode. Lithium recovery system.
In Article 1, The above lithium recovery system further includes a second power supply unit that applies current between the second electrode and the third electrode, and Characterized that when current is applied to the second electrode and the third electrode through the second power supply, an electrochemical oxidation reaction occurs at the second electrode and an electrochemical reduction reaction occurs at the third electrode. Lithium recovery system.
In Article 1, The current collector of the first electrode is an electrode of the waste lithium battery exposed to the outside by crushing, shredding, classifying, scratching, or punching the waste lithium battery. Lithium recovery system.
In Article 1, The above electrolyte membrane is, Composed of a NASICON (Sodium Superionic Conductor)-based solid electrolyte that selectively passes lithium ions, Lithium recovery system.
In Article 1, The above extraction solution is a liquid having lithium ion conductivity, comprising a non-aqueous solvent and a lithium salt, and The above-mentioned non-aqueous solvent is one or more selected from ethylene carbonate (EC), ethylmethyl carbonate (EMC), and tetraethylene glycol dimethyl ether (TEGDME), and The above lithium salt is lithium hexafluorophosphate ( LiPF6 ) or lithium bistrifluoromethanesulfonylimide (LiTFSI), Lithium recovery system.
In Article 1, The above extraction solution is, Characterized by lithium ions being leached from the first electrode immersed in the extraction solution. Lithium recovery system.
In Article 1, The above recovery solution is, One or more selected from distilled water, deionized water, aqueous lithium hydroxide (LiOH) solution, and aqueous lithium chloride (LiCl) solution, Lithium recovery system.
In Article 1, In a first extraction process in which current is applied between the first electrode and the second electrode, Characterized by lithium in the extraction solution being adsorbed onto the surface of the second electrode. Lithium recovery system.
In Article 10, In a second extraction process in which current is applied between the second electrode and the third electrode, Characterized by the detachment of lithium adsorbed on the surface of the second electrode. Lithium recovery system.
In Paragraph 11, In the second extraction process above, the lithium ions in the extraction solution are moved to the recovery tank, thereby forming an aqueous lithium hydroxide solution, characterized by the formation of the aqueous lithium hydroxide solution. Lithium recovery system.
In Paragraph 11, The above second extraction process is characterized by being performed after the above first extraction process. Lithium recovery system.

Description

Electrochemical Lithium Recovery System with Improved Lithium Extraction Efficiency from Waste Batteries The present invention relates to an electrochemical lithium recovery system, and more specifically, to an electrochemical lithium recovery system that uses a waste battery as an electrode and improves the efficiency of extracting lithium from the waste battery. In accordance with global greenhouse gas reduction policies, the electric vehicle (EV) industry is developing rapidly, and as the use of energy storage systems (ESS) linked to renewable energy increases significantly, the demand for lithium-ion batteries (LIBs) is rising sharply. Typically, these lithium-ion batteries are disposed of after about 10 years of use as their capacity decreases, and the volume of used lithium-ion batteries—that is, waste lithium-ion batteries (hereinafter referred to as waste lithium batteries)—is also expected to surge in the future. Accordingly, as interest in the treatment and recycling of spent lithium batteries has increased, various studies have been conducted on technologies for the reuse, extraction, or recovery of spent lithium batteries. Existing recycling processes for spent lithium batteries are broadly classified into dry and wet methods. In the dry method, spent lithium batteries are fed entirely into an electric furnace without separate crushing or sorting steps to melt and separate valuable metals such as cobalt and nickel, while other metals containing lithium are discharged as slag. In this high-temperature dry process, lithium volatilizes and is lost or remains in the slag; recovering this lithium is difficult and incurs high processing costs. In the wet method, the cathode material of spent lithium batteries is crushed and sorted, lithium is leached into a solution, and valuable metals are separated in a solution state through solvent extraction to produce lithium in a metallic or compound state through electrolytic extraction or crystallization processes. However, the wet method is complex and costly, and environmental problems may arise from the use of hazardous compounds, such as acid or alkali solutions, for the leaching of lithium. Meanwhile, a technology for recovering valuable metals from spent lithium batteries without using harmful compounds such as acid solutions has been devised (Patent Document 0001). Specifically, the electrode recovered from the spent lithium battery is heat-treated at a temperature of 180 to 450 degrees to melt and remove the binder, and then the separated electrode active material is obtained and the valuable metals are recovered through an electrolytic method (or electroadsorption deionization (CDI: Capacitive De-Ionization) method) under aqueous conditions. However, since a separate heat treatment process is required to melt and remove the binder of the spent lithium battery in order to recover the electrode active material from the spent lithium battery, additional costs are incurred, and there is a problem that valuable metals containing lithium contained in the cathode active material may be lost due to the high-temperature heat treatment. FIG. 1 schematically illustrates a lithium recovery system according to one embodiment of the present invention. FIG. 2 shows a lithium extraction step in a lithium recovery system according to one embodiment of the present invention. FIG. 3 shows a lithium concentration step in a lithium recovery system according to one embodiment of the present invention. FIG. 4 illustrates a lithium recovery step in a lithium recovery system according to one embodiment of the present invention. Figure 5 shows the results of confirming lithium extraction in the first extraction process using a lithium recovery system according to one embodiment of the present invention. Figure 6 shows the results of a comparison of driving efficiency according to the driving current in a first extraction process using a lithium recovery system according to one embodiment of the present invention. Figure 7 shows the measurement results of the amount of lithium extracted in a first extraction process using a lithium recovery system according to one embodiment of the present invention. Figure 8 shows the results of a comparison of driving efficiency according to the cell scratch area in the first extraction process using a lithium recovery system according to one embodiment of the present invention. Figure 9 shows the results of a comparison of driving efficiency according to the driving current in a second extraction process using a lithium recovery system according to one embodiment of the present invention. Figure 10 shows the results of a comparison of driving efficiency according to the electrolyte membrane area in a second extraction process using a lithium recovery system according to one embodiment of the present invention. The embodiments of the present invention are to be described in detail so that those skilled in the art can easily implement the inv