Methods for lithium metal production direct from litium brine solutions

Abstract

Method(s) and apparatus for direct lithium extraction from brine solutions via a combined solvent extraction and electrowinning process. This process involves solvent extraction integrated with an electrodeposition of lithium metal from nonaqueous solutions to with the added feature of solvent regeneration. The direct lithium metal harvest from brines via a compatible solvent will reduce significantly operational and capital costs related to the current molten salt electrolysis methods for lithium metal production.

What is claimed is: 
     
         1 . A method of preparing lithium metal comprising:
 (A) extracting lithium brine with a solvent to obtain a lithium solution; and   (B) exposing the lithium solution to a voltage or current to obtain lithium metal.   
     
     
         2 . The method of  claim 1 , wherein the lithium metal comprises a purity of at least 80%. 
     
     
         3 . The method of  claim 2 , wherein the lithium metal comprises a purity of at least 90%. 
     
     
         4 . The method of  claim 3 , wherein the lithium metal comprises a purity of at least 95%. 
     
     
         5 . The method according to any one of  claims 1-4 , wherein the lithium brine comprises greater than 0.3 ppm of lithium. 
     
     
         6 . The method of  claim 5 , wherein the brine comprises from about 50 ppm to about 75,000 ppm of lithium. 
     
     
         7 . The method of  claim 6 , wherein the brine comprises from about 100 ppm to about 40,000 ppm of lithium. 
     
     
         8 . The method according to any one of  claims 1-7 , wherein the solvent is immiscible with water. 
     
     
         9 . The method according to any one of  claims 1-8 , wherein the solvent has a greater solubility for lithium than water. 
     
     
         10 . The method according to any one of  claims 1-9 , wherein the solvent is an organic solvent. 
     
     
         11 . The method according to any one of  claims 1-10 , wherein the solvent is a polar aprotic solvent. 
     
     
         12 . The method of  claim 11 , wherein the solvent is a C1-C6 dialkyl carbonate. 
     
     
         13 . The method of  claim 12 , wherein the solvent is diethyl carbonate. 
     
     
         14 . The method according to any one of  claims 1-13 , wherein the method further comprises a second solvent. 
     
     
         15 . The method according to any one of  claims 1-14 , wherein the method further comprises extracting the lithium solution with the second solvent to obtain a purified lithium solution. 
     
     
         16 . The method of  claim 15 , wherein the method further comprises exposing the purified lithium solution to a voltage or current instead of the lithium solution. 
     
     
         17 . The method according to any one of claims  14 - 17 , wherein the second solvent has increased stability at the voltage than the solvent. 
     
     
         18 . The method according to any one of  claims 1-17 , wherein the method comprises using at least two electrodes to apply the voltage or current. 
     
     
         19 . The method of  claim 18 , wherein the method comprises using three electrodes. 
     
     
         20 . The method of either  claim 18 or claim 19 , wherein the method comprises using a working electrode, a counter electrode, and a reference electrode. 
     
     
         21 . The method according to any one of  claims 1-20 , wherein the method comprises applying a voltage from about −6 V to about 6 V. 
     
     
         22 . The method of  claim 21 , wherein the voltage is from about −5 V to about 5 V. 
     
     
         23 . The method of  claim 22 , wherein the voltage is from about −4 V to about 4 V. 
     
     
         24 . The method according to any one of  claims 1-23 , wherein the method is performed continuously. 
     
     
         25 . The method according to any one of  claims 1-24 , wherein the method further comprises returning the lithium solution after the lithium solution has been exposed to the voltage or current to the extraction step. 
     
     
         26 . The method according to anyone of  claims 1-25 , wherein the method further comprises exposing the lithium containing solution or lithium brine with or without other soluble impurity ions to a lithium selective membrane. 
     
     
         27 . The method of  claim 26 , wherein the lithium containing solution or lithium brine with or without other soluble impurity ions is exposed to the lithium selective membrane while the voltage is applied. 
     
     
         28 . The method of  claim 26 , wherein the lithium containing solution or lithium brine with or without other soluble impurity ions is exposed to the lithium selective membrane before the voltage is applied. 
     
     
         29 . The method according to any one of  claims 1-28 , wherein the lithium is deposited on the cathode. 
     
     
         30 . The method of  claim 29 , wherein the lithium is deposited on a metal cathode. 
     
     
         31 . The method of  claim 30 , wherein the lithium is deposited on a copper cathode. 
     
     
         32 . The method according to any one of  claims 1-31 , wherein the lithium is deposited in a roll-to-roll method. 
     
     
         33 . An apparatus for obtaining lithium metal comprising:
 (A) an extraction chamber;   (B) a plating chamber;   wherein the extraction chamber is in fluid communication with the plating chamber;   wherein the plating chamber comprises a cathode and the extraction chamber comprises an anode.   
     
     
         34 . The apparatus of  claim 33 , wherein the apparatus further comprises a lithium selective membrane. 
     
     
         35 . The apparatus of either  claim 33 or claim 34 , wherein the lithium selective membrane is positioned between the extraction chamber and the plating chamber. 
     
     
         36 . The apparatus according to any one of  claims 33-35 , wherein the apparatus further comprises a power source connected to the anode and cathode and capable of delivering a voltage or current. 
     
     
         37 . The apparatus according to any one of  claims 33-36 , wherein the plating chamber further comprises a second reference electrode. 
     
     
         38 . The apparatus according to any one of  claims 33-37 , wherein the cathode is configured to allow roll-to-roll deposition. 
     
     
         39 . The apparatus according to any one of  claims 33-38 , wherein the extraction chamber is configured to allow mixing of liquid inside the chamber. 
     
     
         40 . The apparatus according to any one of  claims 33-39 , wherein the extraction chamber is configured to allow only part of the liquid from the chamber to flow into the plating chamber. 
     
     
         41 . The apparatus according to any one of  claims 33-40 , wherein the extraction chamber is configured to allow only part of the liquid from the chamber to flow into the plating chamber after passing through a desiccant chamber. 
     
     
         42 . A system for cathodic electrodeposition of lithium (Li) onto a moving metal foil, the system comprising:
 (A) a containment cell carrying at least a lithium-containing solution;   (B) a counter electrode extending in the containment cell; and   (C) a working electrode extending in the containment cell,   wherein the working electrode comprising a metal foil configured to be continuously moved through the lithium-containing solution via a roll-to-roll conveyance system, the counter electrode and the working electrode configured to be charged in such a manner as to drive electrodeposition of lithium onto the metal foil extending through the lithium-containing solution.   
     
     
         43 . The system of  claim 42 , further comprising a cation exchange membrane carried in the containment cell and positioned between the counter electrode and the working electrode, the cation exchange membrane and the containment cell together defining a first chamber and a second chamber, the first chamber carrying the working electrode and configured to contain the lithium-containing organic solution, the second chamber carrying the counter electrode and configured to contain a lithium-containing aqueous solution. 
     
     
         44 . The system of  claim 43 , wherein the cation exchange membrane defining a first cation exchange membrane, the system further comprising a second cation exchange membrane in the containment cell, the first and second cation exchange membranes defining a sandwiched liquid membrane therebetween, the sandwiched liquid membrane including a lithium solvent therein. 
     
     
         45 . The system of  claim 42 , further comprising: a series of intermediate transport rolls for carrying the metal foil, the intermediate transport rolls configured to facilitate the definition of a plurality of foil sections, a given foil section being defined between a proximate pair of intermediate transport rolls, the counter electrode being the form of an anode, the anode defining a plurality of anode extensions, at least one anode extension configured to extend between an accompanying pair of adjacent foil sections. 
     
     
         46 . A system for cathodic electrodeposition of lithium (Li) onto a metal foil, the system comprising:
 (A) a containment cell;   (B) a counter electrode extending in the containment cell;   (C) a working electrode extending in the containment cell, the working electrode comprising a metal foil; and   wherein a cation exchange membrane carried in the containment cell and positioned between the counter electrode and the working electrode, the cation exchange membrane and the containment cell together defining a first chamber and a second chamber, the first chamber carrying the working electrode and configured to contain a lithium-containing organic solution, the second chamber carrying the counter electrode and configured to retain at least one of a lithium-containing aqueous solution or a lithium-containing brine, the counter electrode and the working electrode configured to be charged in such a manner as to drive both lithium ion movement through the cation exchange membrane and electrodeposition of lithium onto the metal foil contacting the lithium-containing organic solution.