Molten salt membrane electrolyzer

Abstract

A molten salt, membrane electrolyzer apparatus may include an anolyte compartment containing a molten salt anolyte comprising primarily chloride salts and a lithium carbonate (Li2CO3) feed material. A first and second electrode assemblies each having respective anodes, cathode housings proximate the first anode within the anolyte compartment and in fluid contact with the molten salt anolyte and having a primary transfer portion comprising a porous membrane and cathodes positioned within the first catholyte compartment so that the primary transfer portion is disposed between respective anode and cathode. A power supply can be configured to apply an electric potential between the first anode and the first cathode that is sufficient to initiate electrolysis of lithium carbonate and is greater than the electric potential required to initiate LiCl electrolysis.

What is claimed is: 
     
         1 . A process for producing lithium metal from lithium carbonate using an electrolyzer apparatus having a containment vessel defining an anolyte compartment containing a first anode and a second anode submerged in a common anolyte bath comprising chloride salts, the process comprising:
 a) providing a first cathode housing in the anolyte bath proximate the first anode, the first cathode housing defining a first catholyte compartment containing a first cathode and a molten salt catholyte and being at least partially bounded by a first primary transfer portion disposed between the first cathode and first anode and comprising a first porous membrane configured to permit migration of lithium ions and resist migration of carbonate ions;   b) providing a second cathode housing in the anolyte bath proximate the second anode, the second cathode housing defining a second catholyte compartment containing a second cathode and the molten salt catholyte and being at least partially bounded by a second primary transfer portion disposed between the second cathode and second anode and comprising a second porous membrane configured to permit migration of lithium ions and resist migration of carbonate ions;   c) introducing a lithium carbonate feed material into the anolyte bath;   d) applying an electric overpotential that is sufficient to initiate electrolysis of lithium carbonate feed material and is substantially greater than the equilibrium potential of lithium chloride between the first anode and the first cathode and between the second anode and the second cathode, thereby electrolyzing the lithium carbonate feed material;   e) transferring lithium ions from the anolyte bath into the first catholyte compartment through the first primary transfer portion and resisting the transfer of carbonate ions from the anolyte bath into the first catholyte compartment;   f) transferring lithium ions from the anolyte bath into the second catholyte compartment through the second primary transfer portion and resisting the transfer of carbonate ions from the anolyte bath into the second catholyte compartment; and   g) converting the lithium ions into lithium metal.   
     
     
         2 . The process of  claim 1 , further comprising introducing chlorine gas into the first catholyte compartment via a chlorine delivery system, reacting the chlorine gas with the lithium carbonate to form lithium chloride (LiCl) and carbon dioxide. 
     
     
         3 . The process of  claim 1 , wherein a carbonate ion concentration in the catholyte within the first catholyte compartment is less than in the anolyte bath. 
     
     
         4 . The process of  claim 3 , carbonate ion concentration in first catholyte compartment is less than about 100 ppm. 
     
     
         5 . The process of any one of  claims 1  to  4 , further comprising inhibiting carbon or lithium oxide fouling of the first cathode by introducing chlorine gas into the catholyte in the first cathode compartment. 
     
     
         6 . The process of  claim 1 , further comprising maintaining a current density of between about 0.75 A/cm 2  and about 4 A/cm 2  between the first anode and first cathode and between the second anode and second cathode. 
     
     
         7 . The process of  claim 6 , wherein the current density is at least about 1.2 A/cm 2 . 
     
     
         8 . The process of  claim 1 , further comprising maintaining a concentration of lithium carbonate of at least 0.1 mol % in the anolyte bath. 
     
     
         9 . The process of  claim 8 , further comprising maintaining a concentration of lithium carbonate of at least 0.5 mol % in the anolyte bath. 
     
     
         10 . The process of  claim 1 , further comprising extracting anode gases generated proximate the first anode via an anode gas extraction apparatus and introducing additional lithium carbonate feed material into the anolyte bath when a concentration of chlorine gas in the anodes gases exceeds a predetermined monitoring threshold. 
     
     
         11 . The process of any one of  claims 1  to  10 , wherein a quantity of carbon that is required per unit of lithium metal produced is less than about 0.4 kg C/kg Li. 
     
     
         12 . The process of any one of  claims 1  to  11 , further comprising maintaining at least one of the anolyte and the catholyte at a temperature that is greater than 375° C., or preferably is greater than about 400° C. 
     
     
         13 . The process of  claim 12 , further comprising maintaining the at least one of the anolyte and the catholyte at a temperature that is between about 450° C. and about 700° C. 
     
     
         14 . The process of any one of  claims 1  to  13 , wherein the anolyte and the catholyte each comprise molten LiCl and KCl. 
     
     
         15 . The process of any one of  claims 1  to  14 , wherein the electrolyzer apparatus further comprises a first cathode mounting apparatus extending over an open upper end of the containment vessel and supporting at least the first cathode, and wherein the first cathode mounting apparatus is removable from the containment vessel and the first cathode is removed with the first cathode mounting apparatus while the anolyte bath remains contained within the anolyte compartment. 
     
     
         16 . The process of  claim 15 , wherein the first cathode mounting apparatus comprises a first feed port through which lithium carbonate is introduced into the anolyte bath and wherein removing the first cathode mounting apparatus simultaneously removes the first cathode and the first feed port from the containment vessel. 
     
     
         17 . A molten salt, membrane electrolyzer apparatus for the production of lithium metal from lithium carbonate via an electrolysis process, the apparatus comprising:
 a) a containment vessel defining an anolyte compartment containing a molten salt anolyte bath comprising chloride salts and a lithium carbonate (Li 2 CO 3 ) feed material;   b) a first electrode assembly comprising:
 i. a first anode extending into the anolyte compartment and in fluid contact with the molten salt anolyte bath; 
 ii. a first cathode housing proximate the first anode within the anolyte compartment and in fluid contact with the molten salt anolyte bath, the first cathode housing defining a first catholyte compartment containing a molten salt catholyte comprising chloride salts and being at least partially bounded by a primary transfer portion comprising a first porous membrane configured to permit migration of lithium ions and resist migration of carbonate ions from the anolyte compartment into the first catholyte compartment; 
 iii. a first cathode within the first catholyte compartment, in fluid contact with the catholyte and positioned so that the primary transfer portion is disposed between the first anode and the first cathode; 
   c) a second electrode assembly comprising:
 i. a second anode extending generally into the anolyte compartment and in fluid contact with the molten salt anolyte bath; 
 ii. a second cathode housing proximate the second anode within the anolyte compartment and in fluid contact with the molten salt anolyte bath, the second cathode housing defining a second catholyte compartment containing a molten salt catholyte comprising chloride salts and being at least partially bounded by a primary transfer portion comprising a second porous membrane configured to permit migration of lithium ions and resist migration of carbonate ions from the anolyte compartment into the second catholyte compartment; 
 iii. a second cathode within the second catholyte compartment in fluid contact with the catholyte and positioned so that the second primary transfer portion is disposed between the second anode and the second cathode; 
   d) a power supply configured to apply an electric potential between at least the first anode and the first cathode that that is greater than the electric potential required to initiate electrolysis of the lithium carbonate feed material and is substantially greater than the equilibrium potential of lithium chloride.   
     
     
         18 . The apparatus of  claim 17 , wherein the containment vessel comprises an open upper end and wherein the first anode, first cathode, second anode and second cathode extend downwardly through the open upper end into the anolyte bath. 
     
     
         19 . The apparatus of  claim 17 , wherein the electric potential between the first anode and the first cathode is at least 4V. 
     
     
         20 . The apparatus of  claim 18 , wherein the electric potential between the first anode and the first cathode is at least 7V and may be about 10V. 
     
     
         21 . The apparatus of  claim 18 , wherein the electric potential between the first anode and the first cathode is at least 10V. 
     
     
         22 . The apparatus of any one of  claims 1  to  21 , wherein the first electrode assembly operates at current density of between about 1 A/cm 2  and about 4 A/cm 2 . 
     
     
         23 . The apparatus of  claim 22 , wherein the first electrode assembly operates at current density of about 1.2 A/cm 2 . 
     
     
         24 . The apparatus of any one of  claims 1  to  23 , wherein the first anode comprises a generally planar plate having a first anode active surface facing the first cathode, and the first cathode comprises a generally planar plate that is substantially parallel to the first anode and having a first cathode active surface opposite and facing the anode active surface. 
     
     
         25 . The apparatus of  claim 24 , wherein the first cathode active surface is between about 50% and about 200% of the first anode active surface, and preferably is between about 80% and about 120% of the anode active surface, and more preferably is substantially the same as the anode active surface. 
     
     
         26 . The apparatus of any one of  claims 1  to  25 , wherein the second electrode assembly is adjacent the first electrode assembly such that the first cathode is disposed between and is generally equally spaced between the first anode and the second anode, and wherein an electric potential that is sufficient to initiate electrolysis of lithium carbonate and is greater than the equilibrium potential of lithium chloride is applied between the first cathode and the second anode. 
     
     
         27 . The apparatus of  claim 26 , wherein the first cathode housing comprises a secondary transfer portion disposed between the first cathode and the second anode and comprising a porous membrane to permit migration of lithium ions from the anolyte compartment into the first catholyte compartment and resisting the migration of carbonate ions from the anolyte compartment into the first catholyte compartment. 
     
     
         28 . The apparatus of  claim 27 , wherein the first cathode housing is formed at least substantially entirely from the porous membrane. 
     
     
         29 . The apparatus of  claim 28 , wherein at least some regions of the first cathode housing outside the primary transfer portion and the secondary transfer portion are treated to inhibit the transmission of ions through the regions of the first cathode housing outside the primary transfer portion and the secondary transfer portion. 
     
     
         30 . The apparatus of  claim 29 , wherein the least some regions of the first cathode housing outside the primary transfer portion and the secondary transfer portion are coated or impregnated with an ion blocking material. 
     
     
         31 . The apparatus of  claim 17  wherein the first cathode housing is formed east substantially entirely from the porous membrane. 
     
     
         32 . The apparatus of  claim 31 , wherein at least some regions of the first cathode housing outside the primary transfer portion are treated to inhibit the transmission of ions through the regions of the first cathode housing outside the primary transfer portion. 
     
     
         33 . The apparatus of  claim 32 , wherein the least some regions of the first cathode housing outside the primary transfer portion are coated or impregnated with an ion blocking material. 
     
     
         34 . The apparatus of any one of  claims 17  to  33 , wherein the porous membrane is formed from a ceramic material and having an average pore size of between about 0.1 and about 100 microns, and preferably has a maximum pore size of about 1 micron and average pore size less than about 0.5 microns. 
     
     
         35 . The apparatus of any one of  claims 17  to  34 , wherein a concentration of carbonate ions within the first catholyte compartment is less than about 100 ppm while the apparatus is in use. 
     
     
         36 . The apparatus of any one of  claims 17  to  35 , wherein a concentration of carbonate ions within the first catholyte compartment is less than a concentration of carbonate ions within the anolyte compartment. 
     
     
         37 . The apparatus of any one of  claims 17  to  36 , wherein the first anode is removable from the anolyte compartment independently of the first cathode housing and the first cathode. 
     
     
         38 . The apparatus of any one of  claims 17  to  37  wherein the first anode is removable from the anolyte compartment independently of the second anode. 
     
     
         39 . The apparatus of any one of  claims 17  to  38 , wherein the first anode is removable from the anolyte compartment without draining the molten salt anolyte bath from the anolyte compartment. 
     
     
         40 . The apparatus of any one of  claims 17  to  39 , further comprising a chlorine delivery system configured to introduce chlorine gas into the first catholyte compartment while the apparatus is in use. 
     
     
         41 . The apparatus of  claim 40 , wherein the chlorine gas reacts with Li 2 CO 3  present within the first catholyte compartment to produce LiCl and carbon dioxide, thereby inhibiting carbon or lithium oxide fouling of the first cathode. 
     
     
         42 . The apparatus of  claim 40  or  41 , wherein the chlorine gas reacts with excess lithium within the first catholyte compartment thereby inhibiting damage to the membrane. 
     
     
         43 . The apparatus of any one of  claims 17  to  42 , further comprising a gas extraction apparatus configured to capture product gases formed adjacent the first anode and convey the product gases away from the containment vessel. 
     
     
         44 . The apparatus of any one of  claims 17  to  43 , wherein the anolyte bath is at a temperature that is at least about 375° C., or preferably is at least about 400° C. 
     
     
         45 . The apparatus of  claim 44 , wherein the anolyte bath is at a temperature of between about 450° C. and about 700° C. 
     
     
         46 . The apparatus of any one of  claims 17  to  45 , wherein the first electrode assembly further comprises an anode mounting apparatus extending over the upper end of the containment vessel in a first direction and from which the first anode is suspended, and wherein the anode mounting apparatus is detachable from the containment vessel whereby the first anode is removed from the anolyte compartment. 
     
     
         47 . The apparatus of  claim 46 , wherein the first anode is detachably connected to the anode mounting apparatus. 
     
     
         48 . The apparatus of  claim 46 , wherein the anode mounting apparatus further comprises an electrical connector that electrically connects the first anode to the power supply when the anode mounting apparatus is attached to the containment vessel and wherein the electrical connection between the first anode and the power supply is interrupted when the anode mounting apparatus is detached from the containment vessel. 
     
     
         49 . The apparatus of  claim 46 , wherein the anode mounting apparatus further comprises an insulating layer disposed between the anolyte chamber and the electrical connector to inhibit heat transfer from the molten salt anolyte bath to the electrical connector when the apparatus is in use, and wherein the insulating lining is removable with the anode mounting apparatus. 
     
     
         50 . The apparatus of any one of  claims 46  to  49 , wherein the anode mounting apparatus further comprises a gas extraction apparatus having a gas capture hood positioned above the first anode and configured to capture product gases formed adjacent the first anode and bubbling out of the molten salt anolyte bath and a gas removal conduit extending from the gas capture hood and configured to convey the product gases away from the containment vessel, wherein at least a portion of the gas extraction apparatus is removable with the anode mounting apparatus. 
     
     
         51 . The apparatus of  claim 50 , wherein the gas capture hood is electrically isolated from the first anode. 
     
     
         52 . The apparatus of any one of  claims 46  to  51 , wherein the first electrode assembly further comprises a cathode mounting apparatus extending over the upper end of the containment vessel in the first direction and from which the first cathode is suspended, and wherein the cathode mounting apparatus is detachable from the containment vessel whereby the first cathode is removed from containment vessel with the cathode mounting apparatus. 
     
     
         53 . The apparatus of  claim 52 , wherein the first cathode housing is suspended from the cathode mounting apparatus whereby the first cathode housing is removed from the containment vessel with the cathode mounting apparatus. 
     
     
         54 . The apparatus of  claim 52  or  43 , wherein the cathode mounting apparatus further comprises a lithium extraction assembly that includes a lithium extraction conduit that extends from an upper end proximate the cathode mounting apparatus to a lower end that disposed within the first catholyte compartment to extract lithium metal that collects in the catholyte, and wherein the lithium extraction conduit is removed from the containment vessel with the cathode mounting apparatus. 
     
     
         55 . The apparatus of any one of  claims 52  to  54 , wherein the cathode mounting apparatus further comprises an electrical connector that electrically connects the first cathode to the power supply when the cathode mounting apparatus is attached to the containment vessel and wherein the electrical connection between the first cathode and the power supply is interrupted when the cathode mounting apparatus is detached from the containment vessel. 
     
     
         56 . The apparatus of any one of  claims 52  to  55 , wherein at least one feed port is provided in the cathode mounting apparatus through with the feed material can be introduced into the anolyte compartment. 
     
     
         57 . The apparatus of  claim 56 , wherein the at least one feed port is removable from the containment vessel with the cathode mounting apparatus. 
     
     
         58 . The apparatus of any one of  claims 52  to  57 , further comprising a plurality of cathode mounting apparatuses and anode mounting apparatuses in an alternating arrangement and wherein adjacent ones of the cathode mounting apparatuses and anode mounting apparatuses cooperate to cover substantially the entire upper end of the containment vessel. 
     
     
         59 . The apparatus of any one of  claims 17  to  58 , further comprising a filling tube fluidly connecting the anolyte compartment and the first catholyte compartment whereby anolyte from the anolyte bath can be drawn into the first catholyte compartment when a vacuum is applied to the first catholyte compartment. 
     
     
         60 . The apparatus of any one of  claims 17  to  59 , wherein Li 2 CO 3  within the anolyte bath reacts with Cl 2  produced within the anolyte compartment, thereby converting it to LiCl, CO 2  and O 2 and supressing the emission of Cl 2  from the containment vessel. 
     
     
         61 . The apparatus of any one of  claims 17  to  60 , wherein a quantity of carbon required per unit of lithium metal produced is less than about 0.4 kg C/kg Li. 
     
     
         62 . The apparatus of any one of  claims 17  to  61 , wherein a concentration of dissolved lithium carbonate in the anolyte within the anolyte compartment is greater than 0.1 mol % or may be greater about 1 mol %. 
     
     
         63 . The apparatus of  claim 62 , wherein the concentration of dissolved lithium carbonate concentration of dissolved lithium carbonate in the anolyte within the anolyte compartment is greater than 0.5 mol %. 
     
     
         64 . The apparatus of any one of  claims 17  to  63 , wherein a CO2/O2 ratio in an off-gas produced at the anode is between about 2 and about 2.5. 
     
     
         65 . The apparatus of any one of  claims 17  to  64 , wherein the first porous membrane is formed from a ceramic material and having an average pore size of between about 0.1 and about 100 microns, and preferably has a maximum pore size of about 1 micron and average pore size less than about 0.5 microns. 
     
     
         66 . The apparatus of any one of  claims 17  to  65 , wherein the first porous membrane has an open porosity of between 10-80%, and more preferably between 30-60%. 
     
     
         67 . The apparatus of any one of  claims 17  to  66 , wherein the first porous membrane is substantially rigid. 
     
     
         68 . The apparatus of any one of  claims 17  to  67 , further comprising:
 a) a third electrode assembly comprising:
 i. a third anode extending into the anolyte compartment and in fluid contact with the molten salt anolyte bath; 
 ii. a third cathode housing proximate the third anode within the anolyte compartment and in fluid contact with the molten salt anolyte bath, the third cathode housing defining a third catholyte compartment containing a molten salt catholyte comprising chloride salts and being at least partially bounded by a primary transfer portion comprising a third porous membrane configured to permit migration of lithium ions and resist migration of carbonate ions from the anolyte compartment into the third catholyte compartment; 
 iii. a third cathode within the third catholyte compartment, in fluid contact with the catholyte and positioned so that the primary transfer portion is disposed between the third anode and the third cathode; 
 
 b) a fourth electrode assembly comprising:
 i. a fourth anode extending generally into the anolyte compartment and in fluid contact with the molten salt anolyte bath; 
 ii. a fourth cathode housing proximate the fourth anode within the anolyte compartment and in fluid contact with the molten salt anolyte bath, the fourth cathode housing defining a fourth catholyte compartment containing a molten salt catholyte comprising chloride salts and being at least partially bounded by a primary transfer portion comprising a fourth porous membrane configured to permit migration of lithium ions and resist migration of carbonate ions from the anolyte compartment into the fourth catholyte compartment; 
 iii. a fourth cathode within the fourth catholyte compartment in fluid contact with the catholyte and positioned so that the fourth primary transfer portion is disposed between the fourth anode and the fourth cathode. 
 
 
     
     
         69 . A molten salt, membrane electrolyzer apparatus for the production of lithium metal from lithium carbonate via an electrolysis process, the apparatus comprising:
 a) a containment vessel defining an anolyte compartment containing a molten salt anolyte bath, the anolyte bath comprising chloride salts and more than about 0.1 mol % lithium carbonate (Li 2 CO 3 ) feed material;   b) a plurality of electrode assemblies spaced apart from each other and extending into the anolyte compartment, each electrode assembly comprising:
 i. a cathode housing in fluid contact with the molten salt anolyte bath, the cathode housing defining a catholyte compartment containing a molten salt catholyte comprising chloride salts and being at least partially bounded, by a primary transfer portion comprising a porous membrane configured to permit migration of lithium ions and resist migration of carbonate ions from the anolyte compartment into the catholyte compartment; 
 ii. a cathode positioned within the catholyte compartment, in fluid contact with the catholyte and having an active surface; and 
 iii. an anode in contact with the molten salt anolyte bath and proximate the cathode housing, the anode having an active surface that is substantially equidistant from the active surface of the cathode and being positioned so that the primary transfer portion of the membrane is disposed between the active surface of the anode and the active surface of the cathode; and 
   c) a power supply configured to apply an electric potential to each electrode assembly that is greater than the electric potential required to initiate electrolysis of the lithium carbonate feed material.   
     
     
         70 . The apparatus of  claim 69 , wherein the plurality of electrode assemblies comprises at least ten electrode assemblies arranged in an array within the anolyte compartment. 
     
     
         71 . The apparatus of  claim 69  or  70 , wherein the anode comprises a substantially planar plate and the cathode comprises a substantially planar plate that is parallel to the anode. 
     
     
         72 . The apparatus of  claim 71 , wherein the primary transfer portion of porous membrane is substantially planar and is parallel to both the anode and the cathode. 
     
     
         73 . The apparatus of any one of  claims 69  to  72 , further comprising at least a first and a second anode support apparatus extending across an open upper end of the containment vessel and over the anolyte compartment, the first anode support apparatus supporting at least a first anode and the second anode support apparatus supporting at least a second anode. 
     
     
         74 . The apparatus of  claim 73 , wherein the first anode support apparatus and the first anode supported thereon are removable from the containment vessel independently from the second anode support apparatus. 
     
     
         75 . The apparatus of  claim 74 , wherein the first anode support apparatus and the first anode supported thereon are removable while the anolyte bath is contained within the anolyte compartment. 
     
     
         76 . The apparatus of any one of  claims 73  to  75 , wherein the first anode support apparatus comprises an electrical connector that electrically connects the first anode to the power supply and wherein the electrical connection is interrupted when the first anode support apparatus is removed. 
     
     
         77 . The apparatus of any one of  claims 73  to  76 , further comprising at least a first cathode support apparatus disposed between the first and second anode support apparatuses, and a second cathode support apparatus on an opposing side of the second anode support, each cathode support apparatus across he open upper end of the containment vessel and over the anolyte compartment, the first cathode support apparatus supporting at least a first cathode proximate the first anode and the second cathode support apparatus supporting at least a second cathode proximate the second anode. 
     
     
         78 . The apparatus of  claim 77 , wherein the first cathode support apparatus and first cathode supported thereon are removable from the containment vessel independently from the first anode support apparatus. 
     
     
         79 . The apparatus of  claim 78 , wherein the first cathode support apparatus and first cathode supported thereon are removable from the containment vessel while the anolyte bath is contained within the anolyte compartment. 
     
     
         80 . The apparatus of  claim 78  or  79 , wherein the first cathode support apparatus comprises an electrical connector that electrically connects the first cathode to the power supply and wherein the electrical connection is interrupted when the first cathode support apparatus is removed. 
     
     
         81 . The apparatus of any one of  claims 78  to  80 , wherein a first cathode housing surrounding the first cathode is suspended from the first cathode mounting apparatus whereby the first cathode housing is removed from the containment vessel with the first cathode mounting apparatus. 
     
     
         82 . The apparatus of any one of  claims 69  to  81 , wherein the porous membrane comprises a ceramic material which is non-wetting by lithium metal. 
     
     
         83 . The apparatus of  claim 82 , wherein the non-wetting ceramic material has an open porosity of between about 30% and about 60%. 
     
     
         84 . The apparatus of any one of  claims 69  to  83 , wherein a ratio of an area of the active surface of the anode to an area of the active surface of the cathode is between about 0.5 and 2, and more preferably is between 0.8 to 1.2. 
     
     
         85 . The apparatus of any one of  claims 69  to  84 , further comprising a chlorine delivery system configured to introduce chlorine gas into each catholyte compartment. 
     
     
         86 . The apparatus of  claim 85 , wherein the chlorine gas reacts with lithium carbonate present within the catholyte to product carbon dioxide and lithium chloride. 
     
     
         87 . The apparatus of any one of  claims 69  to  84 , wherein the porous membrane is formed from a ceramic material and having an average pore size of between about 0.1 and about 100 microns and preferably has a maximum pore size of about 1 micron and average pore size less than about 0.5 microns. 
     
     
         88 . The apparatus of any one of  claims 69  to  87 , wherein the electric potential between the anode and the cathode is at least 4V. 
     
     
         89 . The apparatus of  claim 88 , wherein the electric potential between the anode and the cathode is at least 7V and may be about 10V. 
     
     
         90 . The apparatus of  claim 89 , wherein the electric potential between the anode and the cathode is at least 10V. 
     
     
         91 . The apparatus of any one of  claims 69  to  90 , wherein the each electrode assembly operates at current density of between about 1 A/cm 2  and about 4 A/cm 2 . 
     
     
         92 . The apparatus of  claim 91 , wherein each electrode assembly operates at current density of about 1.2 A/cm 2 . 
     
     
         93 . The apparatus of any one  claims 69  to  92 , wherein the power supply configured to apply an electric potential to each electrode assembly that is greater than the equilibrium potential of lithium chloride. 
     
     
         94 . The apparatus of any one of  claims 62  to  93 , wherein the anolyte bath is at a temperature that is at least about 375° C., or preferably is at least about 400° C., or more preferably may be between about 450° C. and about 700° C. degrees Celsius.