Electrochemical Extraction and Conversion of Metals from Liquid Solutions

Abstract

Described herein are tandem methods for producing a lithium-containing product from a lithium-containing solution and systems for performing. A method may involve supplying the lithium-containing solution into a lithium-extraction reactor and applying a negative potential to the working electrode, thereby electrochemically incorporating lithium into the working electrode. The lithium-containing solution may then be replaced with a recovery solution and a positive potential to the working electrode, thereby extracting lithium from the working electrode into the recovery solution. The recovery solution comprising lithium cations is then transferred to a lithium-conversion reactor, and a conversion potential is applied between the electrodes, thereby converting the lithium cations into a lithium-containing product, such as lithium carbonate (Li2CO3), lithium hydroxide (LiOH), lithium chloride (LiCl), and lithium sulfate (Li2SO4). For example, carbon dioxide (CO2) may be pumped through the recovery solution while applying the conversion potential to lithium carbonate (Li2CO3).

1 . A tandem method for producing a lithium-containing product from a lithium-containing solution, the tandem method comprising:
 supplying the lithium-containing solution comprising lithium cations (Li + ) into a lithium-extraction reactor, wherein the lithium-extraction reactor comprises a working electrode and a counter electrode;   applying a negative potential to the working electrode, relative to the counter electrode, thereby electrochemically incorporating the lithium cations (Li + ) into the working electrode;   removing the lithium-containing solution from the lithium-extraction reactor;   supplying a recovery solution to the lithium-extraction reactor;   applying a positive potential to the working electrode, relative to the counter electrode, thereby extracting the lithium cations (Li + ) from the working electrode into the recovery solution;   transferring the recovery solution comprising the lithium cations (Li + ) to a lithium-conversion reactor, wherein the lithium-conversion reactor comprises a cathodic electrode, an anodic electrode, and an ionic exchange membrane positioned between the cathodic electrode and the anodic electrode; and   applying a conversion potential between the cathodic electrode and the anodic electrode, thereby converting the lithium cations (Li + ) in the recovery solution into the lithium-containing product.   
     
     
         2 . The tandem method of  claim 1 , wherein the lithium-containing product comprises lithium hydroxide (LiOH). 
     
     
         3 . The tandem method of  claim 2 , wherein applying the conversion potential between the cathodic electrode and the anodic electrode comprises water splitting into hydrogen gas (H 2 ) and hydroxide ions (OH − ) at the cathodic electrode and reacting the hydroxide ions (OH − ) with the lithium cations (Li + ) to form lithium hydroxide (LiOH). 
     
     
         4 . The tandem method of  claim 1 , further comprising supplying carbon dioxide (CO 2 ) into the lithium-conversion reactor while applying a conversion potential between the cathodic electrode and the anodic electrode, wherein the lithium-containing product comprises lithium carbonate (Li 2 CO 3 ). 
     
     
         5 . The tandem method of  claim 4 , wherein applying the conversion potential between the cathodic electrode and the anodic electrode comprises:
 water splitting into hydrogen gas (H 2 ) and hydroxide ions (OH − ) at the cathodic electrode,   reacting hydroxide ions (OH − ) with the carbon dioxide (CO 2 ) to form bicarbonate anions (HCO 3   − ), and   reacting the bicarbonate anions (HCO 3   − ) with the lithium cations (Li + ) to form lithium carbonate (Li 2 CO 3 ).   
     
     
         6 . The tandem method of  claim 4 , wherein applying the conversion potential between the cathodic electrode and the anodic electrode is performed for an electrode-saturation period of time prior to supplying the carbon dioxide (CO 2 ) into the lithium-conversion reactor. 
     
     
         7 . The tandem method of  claim 1 , wherein the working electrode comprises one or more materials selected from the group consisting of lithium selective compounds, including but not limited to, manganese oxide (MnO 2 ), lithium cobalt oxide (Li 1-x CoO 2  such that 0≤x<1), lithium cobalt phosphate (Li 1-x CoPO 4  such that 0≤x<1), lithium manganese oxide (Li 1-x Mn 2 O 4  such that 0≤x<1), lithium nickel oxide (Li 1-x NiO 2  such that 0≤x<1), lithium nickel cobalt manganese oxide (LiNi x Mn y Co 1-x-y O 2  such that 0≤x≤1, 0≤y≤1, and 0≤x+y≤1), lithium iron phosphate (Li 1-x FePO 4  such that 0≤x<1), lithium manganese phosphate (Li 1-x MnPO 4  such that 0≤x<1), lithium vanadium oxide (Li 1-x V 2 O 5  such that 0≤x<1 or Li 3 V 3 O 8 ), lithium vanadium phosphate (Li 3 V 2 (PO 4 ) 3 ), iron phosphate (FePO 4 ), and vanadium phosphate (V 2 O 5 ). 
     
     
         8 . The tandem method of  claim 1 , wherein applying the negative potential to the working electrode, relative to the counter electrode, further comprises electrochemical incorporating the anions to the counter electrode. 
     
     
         9 . The tandem method of  claim 8 , wherein the counter electrode comprises a material selected from the group consisting of cobalt, a cobalt compound, lithium cobalt oxide (LiCoO 2 ), lithium manganese oxide (Li 1-x Mn 2 O 4 ), lithium nickel cobalt manganese oxide (LiNi x Mn y Co 1-x-y O 2 ), lithium iron phosphate (LiFePO 4 ), polyaniline (PANI), polypyrrole (PPy), silver (Ag), a silver alloy, silver chloride (AgCl), and a Prussian blue analog. 
     
     
         10 . The tandem method of  claim 8 , wherein applying the negative potential to the working electrode, relative to the counter electrode, further comprises electrochemically incorporating the anions into the counter electrode. 
     
     
         11 . The tandem method of  claim 10 , wherein the counter electrode comprises one or more materials selected from the group consisting of activated carbon, carbon paper, carbon nanotubes, conductive polymer, diamond, doped diamond, graphite, graphene, gold, and platinum (Pt). 
     
     
         12 . The tandem method of  claim 1 , wherein the negative potential for the incorporation of the lithium cations (Li + ) into the working electrode is in a range of −0.01 mV to −10 V (vs a reversible hydrogen electrode). 
     
     
         13 . The tandem method of  claim 1 , wherein the positive potential for releasing the lithium cations (Li + ) from working electrodes is in a range of 0.01 mV to 10 V (vs reversible hydrogen electrode). 
     
     
         14 . The tandem method of  claim 1 , wherein the recovery solution comprises one or more materials selected from the group consisting of water (H 2 O), acetone (C 3 H 6 O), acetonitrile, diethyl carbonate (C 5 H 10 O 3 ), dimethyl carbonate (C 3 H 6 O 3 ), ethyl methyl carbonate (C 4 H 8 O 3 ), methyl acetate (C 3 H 6 O 2 ), ethyl acetate (C 4 H 8 O 2 ), dimethoxyethane (C 4 H 10 O 2 ), tetrahydrofuran (C 4 HgO), ethanol (C 2 H 6 O), methanol (CH 3 OH), isopropanol (C 3 HgO), dimethylformamide (C 3 H 7 NO), dimethyl sulfoxide (C 2 H 6 OS), and N-methyl-2-pyrrolidone (C 5 HgNO). 
     
     
         15 . The tandem method of  claim 1 , wherein the conversion potential is in a range of 0.1 mV to 2 V (vs a reversible hydrogen electrode). 
     
     
         16 . The tandem method of  claim 1 , wherein the cathodic electrode comprises one or more catalytically active materials performing a hydrogen evolution reaction (HER) from the group consisting of platinum, platinum-containing catalysts, platinum-supported materials, palladium, palladium-containing catalysts, palladium-supported materials, gold, gold-containing catalysts, gold-supported materials, carbon, carbon-containing catalysts, carbon-supported materials, silver, silver-containing catalysts, and silver supported materials; one or more catalyst support materials selected from the group consisting of carbon papers, carbon clots, and metallic substrates; and one or more polymeric binder selected from the group consisting of anion- or cation-exchange ionomers or a combination of both. 
     
     
         17 . The tandem method of  claim 1 , wherein the anodic electrode comprises one or more catalytically active materials performing an oxygen evolution reaction (OER) selected from the group consisting of nickel, nickel-containing catalysts, nickel-supported materials, iridium, iridium-containing catalysts, iridium-supported materials, ruthenium, ruthenium-containing catalysts, ruthenium supported materials, platinum, platinum-containing catalysts, platinum supported materials, metal borides/borates, palladium, palladium-containing catalysts, palladium supported materials, rhodium, rhodium-containing catalysts, rhodium supported materials, cobalt, cobalt-containing catalysts, cobalt supported catalysts; one or more catalyst support materials selected from the group consisting of carbon papers, carbon clots, and metallic substrates; and one or more polymeric binder selected from the group consisting of anion- or cation-exchange ionomers or a combination of both. 
     
     
         18 . The tandem method of  claim 1 , wherein the ionic exchange membrane is an anion-selective membrane or a cation-selective membrane. 
     
     
         19 . The tandem method of  claim 1 , wherein the lithium-containing product is selected from the group consisting of lithium carbonate (Li 2 CO 3 ), lithium hydroxide (LiOH), lithium chloride (LiCl), and lithium sulfate (Li 2 SO 4 ). 
     
     
         20 . A tandem method for producing a lithium-containing product from a lithium-containing solution, the tandem method comprising:
 supplying the lithium-containing solution comprising lithium cations (Li + ) into a lithium-extraction reactor, wherein the lithium-extraction reactor comprises a working electrode and a counter electrode;   applying a negative potential to the working electrode, relative to the counter electrode, thereby electrochemically incorporating the lithium cations (Li + ) into the working electrode;   removing the lithium-containing solution from the lithium-extraction reactor;   supplying a recovery solution to the lithium-extraction reactor while applying a positive potential to the working electrode, relative to the counter electrode, thereby extracting the lithium cations (Li + ) from the working electrode into the recovery solution;   transferring the recovery solution comprising the lithium cations (Li + ) to a lithium-conversion reactor;   supplying carbon dioxide (CO 2 ) into the lithium-conversion reactor; and   heating the recovery solution to at least 30° C. while stirring the recovery solution in the lithium-conversion reactor thereby converting the lithium cations (Li + ) in the recovery solution into the lithium-containing product comprising lithium carbonate (Li 2 CO 3 ).