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

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.

What is claimed is: 
     
         1 . A method for preparing metallic lithium, the method comprising the steps of:
 (a) placing an electrolytic cell including conductive electrodes in a non-aqueous conductive solvent with a dissolved lithium salt in a high purity inert gas atmosphere; and   (b) applying an electric power to the electrolytic cell in step (a) such that lithium is reduced at a cathode and metallic lithium is deposited on the surface of the cathode.   
     
     
         2 . The method of  claim 1 , wherein in step (a), the electrodes comprise at least two metals selected from the group consisting of gold, platinum, and copper. 
     
     
         3 . The method of  claim 1 , wherein in step (a), the inert gas comprises at least one selected from the group consisting of nitrogen, helium, argon, neon, and xenon. 
     
     
         4 . The method of  claim 1 , wherein in step (a), the lithium salt comprises at least one selected from the group consisting of LiTFSI, LiCl, LiF, LiPF 6 , and LiBF 4 . 
     
     
         5 . The method of  claim 1 , wherein in step (a), the non-aqueous conductive solvent is a non-aqueous conductive solvent containing a bis(trifluoromethylsulfonyl)imide (TFSI) anion and comprises at least one selected from the group consisting of 1-Butyl-3-methyl-pyridinium bis(trifluoromethylsulfonyl)imide ([BMPy]TFSI), 1-methyl-propylpiperidinium bis(trifluoromethylsulfonyl)imide (PP13TFSI), and 1-Ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([EMIM]TFSI). 
     
     
         6 . The method of  claim 5 , wherein the non-aqueous conductive solvent further comprises propylene carbonate (PC), dichloromethane (DCM), tetrahydrofuran (THF), dicyanamide (DCA), or N-methylpyrrolidone (NMP). 
     
     
         7 . The method of  claim 1 , further comprising, before step (a), the steps of:
 (a′) washing the electrodes and the cell with a mixed solution of sulfuric acid and hydrogen peroxide; and   (a″) drying the non-aqueous solvent at 80 to 120° C. for 20 to 30 hours.   
     
     
         8 . The method of  claim 1 , wherein in step (b), the reduction of lithium is performed by pulsed plating such that the lithium is deposited. 
     
     
         9 . The method of  claim 1 , further comprising, after step (b), the step of performing heat treatment on the deposited lithium at 800 to 900° C. for 30 to 90 minutes in an inert gas atmosphere. 
     
     
         10 . The method of  claim 9 , wherein the inert gas comprises at least one selected from the group consisting of nitrogen, helium, argon, neon, and xenon. 
     
     
         11 . A metallic lithium prepared by the method of  claim 1 .