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Method for preparing metallic lithium using electrolysis in non-aqueous electrolyte

a technology of electrolysis and metallic lithium, applied in the field of non-aqueous electrolysis, can solve the problems of reducing reducing the potential of potassium having a higher standard electrode, and inability to use battery applications, etc., and achieves the effect of improving the electrolytic efficiency of lithium and improving the stability of metallic lithium deposits

Inactive Publication Date: 2014-05-29
KUMOH NAT INST OF TECH IND ACADEMIC COOPERATION FOUND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a method for electrolysis of metallic lithium using a non-aqueous electrolyte at low temperatures. The use of this electrolyte significantly improves the efficiency of lithium recovery and the stability of metallic lithium deposits. The method is easy to control, reduces energy consumption, and causes no or minimal environmental pollution.

Problems solved by technology

That is, potassium having a higher standard electrode potential is not readily reduced, but sodium that is reduced to a trace amount increases the reactivity of lithium, thus reducing the stability of metallic lithium.
Lithium containing a small amount of impurities such as sodium can be used in organic chemistry but cannot be used in battery applications.
A method for recovery of lithium comprises adsorbing alkali metals by ion exchange, stripping with an aqueous solution, and precipitating carbonate, but eventually there is no technology other than the above-mentioned molten-salt electrolysis to prepare metallic lithium.
However, the molten-salt electrolysis is a high-temperature process, which has high energy consumption, requires high production costs, and has a significant effect on the environment, and thus various studies for solving these problems have been conducted.
However, the reaction rate of this electrolysis is very low, lithium is deposited into needle-like shapes, or halide anions react with water to act as impurities in deposits, making it very difficult to control the crystallinity and purity of the final product.
Thus, the need to develop optimal conditions for electrolysis in a method for preparing metallic lithium by electrolysis using a simple process compared to other complex processes is urgently required.

Method used

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  • Method for preparing metallic lithium using electrolysis in non-aqueous electrolyte

Examples

Experimental program
Comparison scheme
Effect test

example 1

Electrolytic Reduction of Lithium

[0046]In order to determine the reduction of lithium according to the present invention, the following tests were performed.

[0047]An electrolytic cell with a ternary electrode system was used for the electrolytic reduction of lithium, in which a working electrode was gold and an opposite electrode was platinum. An electrolyte with LiTFSI dissolved in PP13TFSI was used as a non-aqueous conductive solvent. The ternary electrode system refers to the structure in which a reference electrode for precisely monitoring the voltage applied to a cathode is added to an electrolytic cell comprising a working electrode and a relative electrode.

[0048]Before the tests, all the electrodes and the electrolytic cell were washed with a mixed solution of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) at a mixed ratio of 50:50 vol %, and all the non-aqueous solvents were dried at a 100° C. vacuum oven for 24 hours and used for the electrolysis.

[0049]The redox current...

experimental example 1

CV Measurement Depending on Working Electrodes

[0055]The CV results measured when platinum was used as the working electrode in the same electrolytic cell and electrolyte as those in Example 1 are shown in FIG. 3.

[0056]As shown in FIG. 3, the peak interpreted as the reduction of lithium was observed at −1.85 V (vs. Pt-QRE), and the peaks interpreted as the oxidation and reduction of ionic liquids were also observed, and thus it was found that the stability of PP13TFSI as the solvent was very low.

[0057]Moreover, the CV results measured using copper as the working electrode in the same electrolyte are shown in FIG. 4.

[0058]As shown in FIG. 4, it can be seen that the stability of PP13TFSI is similar to the position of the voltage (−2.18 V vs. Pt-QRE) at which the lithium is reduced, but the reduction current is lower than that of gold, indicating that the catalytic performance of gold is most excellent in the electrolytic reduction of metallic lithium.

experimental example 2

Replacement of Non-Aqueous Conductive Solvents

[0059]The electrolytic properties of lithium when gold was used as the working electrode in the same electrolytic cell as that in Example 1 and [EMIM]TFSI with a dissolved lithium salt was used as the conductive electrolyte were measured by cyclic voltammetry. The measurement results of electrochemical properties in [EMIM]TFSI are shown in FIG. 5.

[0060]As shown in FIG. 5, it can be seen that the reduction peak of lithium is −2.7 V which is slightly lower than −2.4. V in PP13TFSI, indicating that other non-aqueous conductive solvents capable of dissolving the lithium salt can be used for the recovery of metallic lithium. Moreover, it can be seen that the stable reduction region of [EMIM]TFSI was shifted from about −2 V to about −3 V in the negative direction by the addition of LiTFSI. However, the cations of the solvent, which determine the cathode limit potential, had the lowest stable cathode potential in EMIM, and the cathode reactivit...

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Abstract

The present invention provides a method for preparing metallic lithium by electrolysis using a non-aqueous electrolyte at low temperature. The method for preparing metallic lithium according to the present invention can directly prepare metallic lithium by electrolysis at a low temperature, and enable mass production, and reduce the manufacturing cost due to its simple process and easy control of electrolytic conditions, and thus the method for preparing lithium thin films according to the present invention can be applied in the industry.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATION[0001]This application claims the benefit of Korean Patent Application No. 10-2012-0133833, filed on Nov. 23, 2012, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.FIELD OF THE INVENTION[0002]The present invention relates to a non-aqueous electrolysis for directly recovering metallic lithium from lithium-containing ores or waste resources.BACKGROUND OF THE INVENTION[0003]Lithium is a chemical element belonging to the alkali metal group and is soft, silvery-white, and corrosive. Thus, lithium is used in alloys for heat transfer applications, batteries, etc., and thus its demand is significantly increasing. The general procedure for preparation of lithium is as follows. First, lithium carbonate is obtained by evaporating water from a salt solution containing lithium and then adding sodium carbonate thereto. At this time, the salt water is concentrated until the lithium ...

Claims

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Application Information

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IPC IPC(8): C25C3/02
CPCC25C3/02C25C1/02C22B26/12
Inventor LEE, CHURL KYOUNGPARK, JE SIKLEE, JAE O.
Owner KUMOH NAT INST OF TECH IND ACADEMIC COOPERATION FOUND
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