Apparatus and method for producing lithium metal

Abstract

An apparatus and method for producing lithium metal by electrolysis of LiCl in a membrane-less electrolytic cell is provided. The method and apparatus of the present invention utilizes a liquid-liquid separator, which may be at least one film coalescer or at least one centrifuge, to coalesce or separate the lithium metal from the Li metal / electrolytic medium mixture produced in the electrolytic cell. 2 A method for producing lithium metal from lithium oxynitride is also provided, the method comprising: 2 Supplying O or Li 2 The method includes providing LiCl generated from O.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 63 / 299,114, filed January 13, 2022. All of the above documents are incorporated by reference herein in their entirety. The present invention relates to an apparatus and method for producing Li metal, more particularly, the method and apparatus employs a selected liquid-liquid separator. The present invention also relates to an apparatus and method for producing Li metal from lithium oxide. [Background technology]

[0002] It is known to produce lithium metal through the electrolysis of lithium-containing molten salts. Impurities of any kind in lithium metal are highly undesirable when used in nuclear technology, alloy production, and lithium batteries.

[0003] In commercial practice, metallic lithium is produced by electrolysis of a molten mixture of lithium chloride and potassium chloride according to the following global reaction: LiCl → Li + Cl2

[0004] The molten salt mixture is electrolyzed to produce Li metal at the cathode and chlorine gas at the anode.

[0005] In conventional cells with a diaphragm, a porous diaphragm, or more frequently a metal sheet with a certain open area (about 30-50%), is inserted between the anode and the cathode to aid in the separation of the electrolysis products. Droplets of liquid lithium metal slowly rise to the surface of the molten mixture on the cathode side of the diaphragm and, on the way, coalesce into larger droplets. Thus, liquid Li metal accumulates at the surface of the molten mixture on the cathode side of the diaphragm, where it is skimmed off. Chlorine gas is collected on the anode side of the diaphragm.

[0006] However, the use of such membranes is associated with the following problems: Short life span due to corrosion (2-6 months), - Debris clogging (increased cell voltage), Loss of alignment (cell short circuit), Gas covering of the anode (higher current density, resulting in higher voltage and erosion of the anode), and Anode corrosion (increasing anode-cathode gap, resulting in increased cell voltage).

[0007] Diaphragm-free electrolysis is also known, allowing for a reduction in cell voltage and its attendant problems and eliminating the above-mentioned problems associated with diaphragms.

[0008] Diaphragm-free electrolysis is achieved by rapid natural circulation of the electrolytic medium, which results from the entrainment in the electrolytic medium of chlorine bubbles generated at the anode. In this process, the flow of the electrolyte is due to the gas lift pumping action of the rising chlorine gas. The electrolytic medium is entrained vertically by the upward movement of the chlorine bubbles in the gap located between the anode and the cathode, and then descends into the space located beyond the cathode to recirculate in the space between the anode and the cathode. The circulation rate of the medium is fast: if Vo is the movement rate of the electrolytic medium entering the cell in the absence of natural recirculation, the actual reached velocity V is about 250 times Vo due to the recirculation. The electrode distance must be controlled because if it is too large, the minimum rising speed is not reached, and if it is too small, the undesirable contact between the lithium metal droplets and the chlorine gas increases. In both cases, the back reaction of lithium metal with chlorine gas results in a lower current efficiency.

[0009] Typically in such processes, the rising molten mixture is collected adjacent the surface level of the molten mixture and removed from the electrolytic cell, then fed into a decantation tank sealed from the chlorine gas atmosphere in the electrolytic cell, the electrolyte and lithium are separated under this protective gas atmosphere, the metallic lithium is discharged and the electrolyte is returned to the electrolytic cell.

[0010] The use of lithium chloride in these processes remains problematic. Indeed, LiCl is very hygroscopic and difficult to dry, which can increase costs and introduce impurities. More importantly, there can be residual water leading to the formation of oxygen-containing products and hydrogen, with the attendant risk of explosion and oxidation of the anode. It has been proposed to use Li2CO3 in addition to or in replacement of LiCl in the electrolytic cell. However, this is only possible in electrolytic cells using a diaphragm. Otherwise, Li2CO3 can react with the lithium produced at the cathode according to the following reaction to form elemental carbon and lithium oxide: Li2CO3+4 Li→3 Li2O+C In this case, carbon may accumulate within the cells in the form of sludge. Summary of the Invention

[0011] According to the present invention, there is provided: 1. An apparatus for producing lithium metal by electrolysis, the apparatus comprising: A liquid-liquid separator; and a diaphragm-free electrolysis cell, an anode and a cathode immersed in an electrolytic medium containing molten LiCl; a chlorine gas outlet located at the top of the cell; a Li metal / electrolytic medium mixture outlet adjacent to a surface level of the electrolytic medium within the cell, the mixture outlet being in fluid communication with a liquid-liquid separator to permit passage of a mixture of electrolytic medium and lithium metal produced by the electrolytic cell into the liquid-liquid separator; The apparatus wherein the liquid-liquid separator comprises at least one film coalescer or at least one centrifuge for separating lithium metal produced by the electrolytic cell from the electrolytic medium. 2. The apparatus of embodiment 1, wherein the liquid-liquid separator comprises at least one film coalescer, preferably the liquid-liquid separator comprises at least two or more film coalescers in series. 3. An apparatus according to any one of the preceding claims, wherein the liquid-liquid separator comprises at least one centrifuge, preferably the liquid-liquid separator comprises two or more centrifuges in series. 4. The apparatus of any one of embodiments 1-3, wherein the liquid-liquid separator comprises at least one film coalescer in series with at least one centrifuge. 5. An apparatus according to any one of the preceding claims, wherein the film coalescer(s) is / are a plate separator and / or a packed bed column, preferably the film coalescer(s) is / are a plate separator. 6. An apparatus according to any one of the preceding claims, wherein the centrifuge(s) is / are a cyclone and / or a centrifugal separator, preferably, the centrifuge(s) is / are a cyclone. 7. The apparatus of any one of embodiments 1-6, wherein the electrolytic medium further comprises molten lithium oxide, molten lithium carbonate, and / or molten alkali halide (preferably, molten alkali chloride, more preferably, molten KCl). 8. The device of any one of embodiments 1-7, wherein the cell further comprises an electrolyte medium inlet facing toward the base of the cell. 9. The apparatus of any one of embodiments 1-8, further comprising an electrolysis medium reservoir and a first conduit fluidly connecting a base of the reservoir to a base of the cell. 10. An apparatus as described in embodiment 9, wherein the reservoir is equipped with a LiCl / LiCl precursor inlet located toward the top of the reservoir. 11. The apparatus of embodiment 9 or 10, further comprising a chlorine bubbler in the reservoir. 12. The apparatus of embodiment 11, further comprising a fourth conduit fluidly connecting the chlorine gas outlet of the cell and a chlorine bubbler in the reservoir. 13. An apparatus according to any one of embodiments 9 to 12, wherein the reservoir is equipped with a gas outlet for removal of by-product gases. 14. The apparatus of any one of the preceding embodiments, further comprising a collection tank for collecting a liquid stream comprising Li metal produced by the liquid-liquid separator. 15. The apparatus of embodiment 14, wherein the collection tank is located below the liquid-liquid separator. 16. An apparatus as described in embodiment 14 or 15, further comprising a second conduit fluidly connecting the collection tank to the reservoir, preferably the second conduit terminating at a desired height relative to the level of the electrolysis medium in the collection tank. 17. An apparatus according to any one of embodiments 14 to 16, wherein the collection tank is provided with a lithium metal outlet for discharging the produced lithium metal. 18. The apparatus of any one of the preceding embodiments, wherein the liquid-liquid separator (and collection tank, if present) is enclosed within the separation chamber, preferably immediately adjacent to the electrolysis cell. 19. The apparatus of embodiment 18, wherein the liquid-liquid separator is located between and immediately adjacent to the electrolysis medium reservoir and the electrolysis cell. 20. A chlorination reactor for the chlorination of LiO to LiCl or a LiCl-LiO mixture, the chlorination reactor being equipped with a chlorine gas inlet, an oxygen gas outlet, a LiO inlet, a LiCl / LiCl-LiO mixture outlet, and a heating element; 20. The apparatus of any one of the preceding embodiments, further comprising a fifth conduit connecting the LiCl / LiCl-Li2O mixture outlet of the chlorination reactor to either the LiCl / LiCl precursor inlet of the reservoir or the electrolyte medium inlet of the cell. 21. The apparatus of embodiment 20, further comprising a sixth conduit fluidly connecting the chlorine gas outlet of the cell and the chlorination reactor's chlorine gas inlet. twenty two. A dehydration reactor for the production of Li2O from LiOH, the dehydration reactor being equipped with a water vapor outlet, a LiOH inlet, a Li2O outlet, a heating element and / or a vacuum pump; 22. The apparatus of any one of the preceding embodiments, further comprising a seventh conduit connecting the LiO outlet of the dehydration reactor to the LiO inlet of the chlorination reactor, the LiCl / LiCl precursor inlet of the reservoir, or the electrolyte medium inlet of the cell. twenty three. A decarbonation reactor for producing Li2O from Li2CO3, the decarbonation reactor being equipped with a CO2 gas outlet, a Li2CO3 inlet, a Li2O outlet, a heating element and / or a vacuum pump; and an eighth conduit connecting the LiO outlet of the decarbonation reactor to the LiO inlet of the chlorination reactor, the LiCl / LiCl precursor inlet of the reservoir, or the electrolyte medium inlet of the cell. 24. A method for producing lithium, comprising: a) electrolyzing an electrolysis medium containing molten LiCl in a membrane-free electrolysis cell; b) collecting a mixture of lithium metal and electrolytic medium from the cell; and c) combining or separating lithium metal from the mixture using a liquid-liquid separator, wherein the liquid-liquid separator comprises at least one film coalescer or at least one centrifuge. 25. The method of embodiment 24, wherein the liquid-liquid separator comprises at least one film coalescer, preferably the liquid-liquid separator comprises at least two or more film coalescers in series. 26. The method of embodiment 24 or 25, wherein the liquid-liquid separator comprises at least one centrifuge, preferably the liquid-liquid separator comprises at least two or more centrifuges in series. 27. The method of any one of embodiments 24 to 26, wherein the liquid-liquid separator comprises at least one film coalescer in series with at least one centrifuge. 28. The method of any one of embodiments 24 to 27, wherein the film coalescer(s) is / are a plate separator and / or a packed bed column, preferably the film coalescer(s) is / are a plate separator. 29. The method according to any one of embodiments 24 to 28, wherein the centrifuge(s) are cyclones and / or centrifugal separators, preferably, the centrifuge(s) are cyclones. 30. The method of any one of embodiments 24-29, further comprising the steps of: supplying molten LiCl, a precursor thereof, or a mixture thereof to the cell; and, when a precursor is supplied, allowing chlorine gas produced by the cell to chlorinate the precursor, thus resulting in molten LiCl. 31. The method of embodiment 30, further comprising the step of retaining the molten LiCl, its precursors, or mixtures thereof in an electrolysis medium reservoir prior to providing the molten LiCl, its precursors, or mixtures thereof to the cell. 32. The method according to embodiment 30 or 31, wherein molten LiCl or a mixture of molten LiCl and its precursors (preferably, molten LiCl alone) is provided to the cell. 33. The method of embodiment 31 or 32, further comprising adding LiCl, its precursors, and / or mixtures thereof to the bath of molten LiCl in the electrolysis medium reservoir to replenish the electrolysis medium. 34. The method of any one of embodiments 31-33, further comprising generating molten LiCl from a LiCl precursor in a reservoir. 35. The method of claim 34, wherein the precursor is added to molten LiCl in a reservoir and chlorine gas is preferably bubbled into the reservoir, more preferably using chlorine gas generated in the cell. 36. The method of any one of embodiments 30-36, wherein the precursor is lithium oxide, lithium carbonate, and / or a lithium salt other than LiCl, preferably, the precursor is lithium oxide or lithium carbonate, more preferably, the precursor is lithium oxide. 37. The method of any one of embodiments 30-36, further comprising the step of producing LiCl or a LiCl-Li2O mixture by chlorination of lithium oxide (preferably using chlorine gas, most preferably using chlorine gas produced in the cell) and then adding LiCl or a LiCl-Li2O mixture to the reservoir or cell. 38. The method of any one of embodiments 30-37, further comprising the step of producing Li2O by dehydration of lithium hydroxide or decarbonation of lithium carbonate. 39. The method of any one of embodiments 24-38, further comprising collecting a liquid stream produced by the liquid-liquid separator, the stream comprising Li metal and electrolytic medium, allowing the stream to be decanted into a phase of Li metal above a phase of electrolytic medium. 40. The method of any one of embodiments 24-39, further comprising recycling the electrolytic medium from the liquid-liquid separator. 41. The method of any one of embodiments 24 to 41, further comprising using heat from the cell to heat the separator. 42. A method for producing lithium metal from Li2O, the method comprising: 1) providing i) LiO, ii) LiCl generated from LiO, or iii) a mixture thereof to an electrolysis cell, the electrolysis cell including an anode, a cathode, and an electrolysis medium including molten LiCl; 2) electrolyzing molten LiCl in the electrolytic cell to produce Li metal and chlorine gas. 43. The method of embodiment 42, wherein Li2O is supplied to the cell in step 1) and chlorine gas produced in step 2) can react with Li2O to produce LiCl, which is then electrolyzed in step 2) to produce Li metal. 44. The method of embodiment 42, further comprising chlorinating Li2O to produce LiCl, and then providing the LiCl produced from Li2O in step 1) to the cell, with or without unreacted Li2O. 45. The method of embodiment 44, wherein the chlorinating is carried out in a chlorination reactor. 46. ​​The method of embodiment 44 or 45, comprising bubbling chlorine through a bath of molten LiCl containing Li2O in a chlorination reactor, and then feeding the resulting LiCl, with or without unreacted Li2O, to the electrolysis cell. 47. The method of embodiment 46, wherein a gas bubbler is used to bubble the chlorine. 48. The method of embodiment 46 or 47, wherein the chlorine gas produced in step 2) is used for the bubbling in the chlorination reactor. 49. The method of embodiment 44 or 45, comprising chlorinating solid Li2O using chlorine gas and then feeding the resulting LiCl, with or without unreacted Li2O, to an electrolytic cell. 50. The method of embodiment 49, wherein the chlorine gas produced in step 2) is used to chlorinate solid Li2O. [Brief description of the drawings]

[0012] In the accompanying drawings: [Figure 1] FIG. 2 is a cross-sectional view of an example of a single plate separator. [Diagram 2] FIG. 2 is a cross-sectional view of an example of a multi-plate separator. [Diagram 3] 13A-13C are cross-sectional views of examples of single plate separators having textured or floor supporting locations. [Figure 4] FIG. 2 is a cross-sectional view of an example of a packed bed column. [Diagram 5] FIG. 2 is a cross-sectional view of an example of a multi-stage column. [Figure 6] FIG. 2 is a partial cross-sectional view of an example cyclone. [Figure 7] FIG. 2 is a cross-sectional view of an example of a tubular centrifuge. [Figure 8] 1 is a scheme showing the configuration of an electrolysis cell, a separation chamber, and a reservoir in an embodiment of the device of the present invention. [Figure 9] 1 is a scheme showing the configuration of an electrolysis cell, a separation chamber, and a reservoir in another embodiment of the device of the present invention. [Figure 10] 1 is a cross-sectional view of an apparatus according to an embodiment of the present invention. [Figure 11] 4 is a cross-sectional view of an apparatus according to another embodiment of the present invention. [Figure 12] 11 is a cross-sectional view of an apparatus according to yet another embodiment of the present invention. [Figure 13]The chlorination rate of Li2O to LiCl in a molten LiCl-KCl mixture at 400 °C is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present application is an apparatus and method for producing lithium using an undivided (i.e., diaphragm-free) electrolytic cell, i.e., a cell using the gas lift effect. As mentioned above, in such cells, it is well known that reducing the electrode distance to a near-optimal distance has the desired effect of rapidly entraining chlorine gas bubbles and small Li droplets generated at both electrodes upright toward the surface of the electrolytic medium (molten LiCl salt) used in the cell, while reducing the likelihood that they will interact with each other and form undesirable lithium chloride.

[0014] However, this gas lift technique is not without problems. Indeed, in such a process it is essential to ensure that the mixture of metal and molten salt rising in the interelectrode space is quickly removed. However, the short residence time of the lithium metal droplets required to achieve reasonable current efficiencies means that the very small Li metal droplets generated at the cathode do not have enough time to coalesce efficiently. Also, the increased rising speed of the chlorine bubbles generated at the anode creates a fairly high turbulence in the space between the anode and the cathode, which retards or even prevents the coalescence of the Li droplets in the electrolytic cell. Therefore, the mixture of metal and molten salt removed from the cell contains very small Li metal droplets dispersed in the molten salt.

[0015] All of this makes it difficult to separate the Li droplets from the molten salt phase. Specifically, due to the droplet size, it takes a long time for the Li metal in the decantation tank taught by the prior art to separate from the molten salt(s), even when using a device such as that taught in US 4,740,279. Therefore, a large capacity decantation reservoir is needed that can contain all the liquid received from the electrolysis cell for as long as necessary to achieve separation.

[0016] It should be remembered that the Li metal / salt separation is of course made more difficult by the high temperatures involved, i.e., high enough that LiCl and lithium metal are liquid, and that rapid separation needs to be achieved if lithium is produced at a high rate.

[0017] Moreover, such separations are made even more difficult by the fact that the liquids to be separated are not classical water / oil emulsions. However, most conventional separation techniques target such emulsions; in other words, they aim to separate a hydrophilic medium (water) from a hydrophobic one (oil). Liquid lithium metal and molten LiCl, however, do not fit within that paradigm.

[0018] Herein, liquid Li metal is more advantageously separated from the molten salt(s) by density differences. For example, at a temperature of 450° C., the molten salt LiCl has a density of about 1.64 g / cm 3 whereas liquid Li metal has a density of about 0.490 g / cm 3 The present invention uses a device that uses a specific separation strategy based on this density difference to accelerate the coalescence of Li droplets, which significantly reduces the time required to efficiently separate Li droplets from the molten salt. This results in a significant increase in the productivity of the electrolysis cell, since it eliminates the need for large decantation reservoirs as taught in the prior art.

[0019] More specifically, two types of liquid-liquid separators can be used in the apparatus and method of the present invention: Film coalescer: a high surface area device that spreads the liquids to be separated into a thin film (i.e., over a large surface) and reduces their velocity; and · Centrifuge: A device that uses centrifugal force to separate liquids. These devices have a compact geometry and high separation efficiency, both of the key characteristics required for good separation and eventual commercial-scale implementation of membraneless electrolysis cells.

[0020] Upon exiting such a device, the liquid Li metal may either be completely separated from the molten salt or may be in the form of droplets dispersed in the molten salt, although it should be noted that the droplets exiting such a device are larger than when they enter the separator. In such a case, separation of the liquid Li metal is desirably accelerated (e.g., by decantation, e.g., in a collection tank that captures the liquid exiting the device).

[0021] Different kinds of film coalescers can be used, all based on the same principle: spreading the flow of liquid to be separated over a high surface area structure or assembly, leading to the formation of a thin film and a slowing down of the flow of the Li droplet-molten salt mixture. In fact, the combination of a short upward path and a low velocity of the mixture promotes the hydrodynamic coalescence of the Li droplets and therefore their separation from the molten salt electrolyte.

[0022] Examples of film coalescers include plate separators and packed bed columns.

[0023] In a plate separator, at least one plate is used to spread the liquid to be separated into a film. The liquid certainly spreads on the plate(s) and forms a film. In embodiments, particle beds, textures or baffles are added to the plate surfaces to enhance separation. The plates can be flat, smooth, curved, coated or textured to provide properties that can increase residence time, surface contact, adhesion or separation.

[0024] Figure 1 shows a single plate separator (labeled plate) over which the mixture to be separated (M) spreads before dropping into a collection tank as a split mixture (SM). Figure 2 shows a multi-plate separator in which the mixture (M) spreads over three plates in succession before dropping into a collection tank as a split mixture (SM). Figure 3 shows a single plate separator supporting a bed of particles over which the mixture to be separated (M) spreads before dropping into a collection tank as a split mixture (SM).

[0025] In a packed bed column, a bed of particles is used to spread the liquid to be separated into a film. The liquid does spread around the particles forming a film. In embodiments, the particles may be made of metal, composite or ceramic and a coating may be added.

[0026] Figure 4 shows a packed bed column into which the mixture to be separated (M) is introduced and from which the mixture with coalesced lithium droplets is discharged, while Figure 5 shows a multi-stage column comprising several plates in series into which the mixture to be separated (M) is introduced and from which the mixture with coalesced lithium droplets is discharged.

[0027] In any case, to ensure long life, the materials used must exhibit resistance to the corrosive environment involved in such separation. In an embodiment, the plate(s), particle bed, texture and / or baffles are made of metal, composite or ceramic. They can also be coated.

[0028] Different kinds of centrifuges can be used, all based on the same principle: centrifugal force propels the Li droplets towards the surface of the molten salt, where they coalesce and form much larger Li droplets that separate from the molten salt much more quickly and easily.

[0029] Examples of centrifugal separators include cyclones (which have no moving parts) and centrifuges (which have moving parts).

[0030] In a cyclone, the liquid to be separated is injected tangentially into a vessel with sufficient fluid pressure energy to produce a rotational fluid motion. Such a rotational motion causes relative movement of the products suspended in the fluid, resulting in their separation from each other or from the fluid. Figure 6 shows an example of a cyclone in which the feed (mixture M) is injected tangentially. The light and heavy fractions contained in the feed are separated, the light fraction (overflow, Li metal) being pushed towards the overflow outlet located at the top of the vessel, while the heavy fraction (molten salt) exits from the underflow outlet at the bottom of the vessel. In fact, the mechanism of the cyclone is based on the principle of centrifugal force, which causes the heavy phase to separate from the light phase due to density differences. When the fluid is injected tangentially into the cyclone, it moves downwards and close to the wall, but gradually, due to pressure losses, the light phase is driven towards the center and upwards to exit from the overflow outlet, while the heavy phase maintains its movement downwards and close to the wall to exit from the underflow outlet.

[0031] The cyclone can have a variety of configurations, as known in the art, for example: · The entrance can be simple, spiral, single entry, or multi-entry; The body can be a cylinder-cylinder, cylinder-cone, cylinder-cone-cone, or a vortex finder. All of these configurations are contemplated for use with the present apparatus and methods.

[0032] A centrifuge is a device that spins liquids at high speeds in a container, thereby separating liquids of different densities. So-called overflow centrifuges are preferred, in which the separated heavy and light phase suspensions are discharged and the liquid to be separated is constantly added. Common types of such centrifuges include separator centrifuges (such as solid bowl centrifuges and conical plate centrifuges), tubular centrifuges, and decanter centrifuges.

[0033] Figure 7 shows an example of a tubular centrifuge used for the continuous separation of liquids. In this case, the rotating bowl is made of a long hollow tube. For continuous separation, the fluid mixture to be centrifuged enters one end of this tube near the central axis. The separated liquids are removed in two separate streams towards the other end of the tube. The heavy phase is removed circumferentially, while the light phase is pushed forward and removed from the end of the tube.

[0034] In embodiments, two or more of the above devices (of the same or different types) are used in series to enhance the coalescence of the lithium droplets. For example, two centrifuges can be used in series, or a plate separator followed by a packed bed column can be used.

[0035] Apparatus with liquid-liquid separator In another aspect of the present invention, there is provided an apparatus for producing lithium metal by electrolysis, the apparatus comprising: A liquid-liquid separator; and a diaphragm-free electrolysis cell, an anode and a cathode immersed in an electrolytic medium containing molten LiCl; a chlorine gas outlet located at the top of the cell; a Li metal / electrolytic medium mixture outlet adjacent to a surface level of the electrolytic medium within the cell, the mixture outlet being in fluid communication with a liquid-liquid separator to permit passage of a mixture of electrolytic medium and lithium metal produced by the electrolytic cell into the liquid-liquid separator; The liquid-liquid separator comprises at least one film coalescer or at least one centrifuge for separating lithium metal produced by the electrolytic cell from the electrolytic medium.

[0036] The mixture outlet allows the Li metal / electrolysis media mixture produced by electrolysis to exit the cell and may include, for example, a hole in the wall separating the cell from a liquid-liquid separator, chute, or siphon.

[0037] As described above, the separator accelerates the coalescence of the liquid Li metal droplets and their decantation from the electrolysis medium (compared to simply draining the mixture in a decantation tank), which advantageously eliminates the need for a decantation tank with sufficient volume to contain all the electrolysis medium and liquid Li metal produced in the entire time it takes for such "natural" decantation to occur.

[0038] In an embodiment, the liquid-liquid separator comprises two or more film coalescers in series.

[0039] In an embodiment, the liquid-liquid separator comprises two or more centrifuges in series.

[0040] In an embodiment, the liquid-liquid separator comprises at least one film coalescer in series with at least one centrifuge.

[0041] The liquid-liquid separator, film coalescer, and centrifuge are as described in the previous section.

[0042] Typically, the anode is cylindrical and the cathode is tubular, and the anode is surrounded by the cathode. As mentioned above, it is known to adjust the interelectrode distance (i.e., the distance between the anode and the cathode) to a near-optimal distance, which has the desired effect of quickly entraining the chlorine bubbles and the small Li droplets generated at both electrodes upright towards the surface of the electrolytic medium (molten LiCl salt) used in the cell, while reducing the possibility that they will interact with each other and form undesirable lithium chloride.

[0043] Typically, the anode is made of graphite, although other materials such as carbon, semi-graphitic carbon, glassy carbon, ceramic alloys or inert alloys may also be used.

[0044] Typically, the cathode is made of mild steel, although the possibility of using Ti or Ni has also been proposed.

[0045] As mentioned above, the electrolytic medium comprises molten LiCl. In an embodiment, the electrolytic medium further comprises molten lithium oxide, molten lithium carbonate and / or molten alkali halide (preferably an alkali chloride such as KCl). However, in a preferred embodiment, the electrolytic medium does not comprise lithium carbonate, and preferably does not comprise lithium carbonate and lithium oxide. Most preferably, the electrolytic medium is molten LiCl alone or in combination with an alkali halide, preferably KCl (which lowers the melting point of the mixture). In an embodiment, the electrolytic medium consists only of molten LiCl, or a mixture of LiCl and KCl, and unavoidable impurities. In an embodiment, the electrolytic medium consists only of molten LiCl and unavoidable impurities.

[0046] In an embodiment, LiCl, its precursor, or a mixture thereof is fed to the cell to replenish the electrolytic medium. In a preferred such embodiment, LiCl, or a mixture of LiCl and a precursor, more preferably LiCl (or alternatively, a LiCl precursor), is fed to the cell. In such a case, the cell further comprises an electrolyte medium inlet facing towards the bottom of the cell. In an embodiment, the precursor is lithium oxide, lithium carbonate, and / or a lithium salt other than LiCl, preferably lithium oxide or lithium carbonate, more preferably lithium oxide.

[0047] In embodiments where Li2O is used as the LiCl precursor (either alone or in a mixture with LiCl), Li2O is For example, by dehydration of lithium hydroxide (2LiOH→Li2O+H2O) in a dehydration reactor, or For example, it can be produced either by decarbonation of lithium carbonate (Li2CO3 → Li2O + CO2) in a decarbonation reactor. Such reactors are discussed further below.

[0048] In an embodiment, LiCl or a LiCl-LiO mixture is produced by the chlorination of lithium oxide in a chlorination reactor and then added to the cell. The ongoing reaction is as follows: 2Li2O+2Cl2→4LiCl+O2 When the reaction is incomplete, some unreacted Li2O remains and a LiCl-Li2O mixture is obtained, which is not harmful because, contrary to Li2CO3, Li2O does not react detrimentally with Li metal.

[0049] In a preferred embodiment, the apparatus further comprises an electrolysis medium reservoir and a first conduit fluidly connecting a base of the reservoir to a base of the cell. The first conduit connecting the reservoir to the cell conveys the electrolysis medium from the reservoir to the cell. The reservoir can simply hold the electrolysis medium or can function as a reactor in which LiCl is produced. Such embodiments are discussed further below.

[0050] In a preferred embodiment, the apparatus further comprises a collection tank for collecting a liquid stream comprising Li metal produced by the liquid-liquid separator, hi an embodiment, the collection tank comprises a lithium metal outlet for discharging the produced lithium metal.

[0051] In an embodiment, the collection tank is located below the liquid-liquid separator. In such an embodiment, the flow of liquid containing Li metal may simply fall from the liquid-liquid separator into the collection tank.

[0052] If the flow collected in the collection tank also contains the electrolysis medium, the collection tank can further function as a decantation tank, allowing for the final separation of the Li metal from the electrolysis medium. In an embodiment, the device further comprises a second conduit, fluidly connecting the collection tank (where the electrolysis medium accumulates) to the reservoir. In that way, the electrolysis medium can be reused in the electrolysis cell. In an embodiment, the second conduit terminates at a desired height relative to the level of the electrolysis medium in the collection tank. This is a simple and effective means for controlling the level of the electrolysis medium in the collection tank. In some alternative embodiments, for example embodiments in which the device does not comprise an electrolysis medium reservoir, a third conduit fluidly connects the base of the collection tank to the electrolyte medium inlet of the cell.

[0053] In a more preferred embodiment, the liquid-liquid separator (and collection tank, if present) are enclosed within the separation chamber. Preferably, the separation chamber is located immediately adjacent to the electrolysis cell. In an embodiment, the separation chamber is located between the electrolysis medium reservoir and the electrolysis cell, and immediately adjacent to the electrolysis medium reservoir and the electrolysis cell. The advantage of such an embodiment is that the heat released from the electrolysis cell is used to maintain the required temperature in both the separation chamber and the electrolysis medium reservoir. To achieve this, the cell, separation chamber, and reservoir may be in parallel, as shown in FIG. 8, or preferably circumferentially enclosed with the cell inside, as shown in FIG. 9.

[0054] If desired, additional heating elements can be provided to heat the separation chamber and / or the electrolytic medium reservoir.

[0055] In an embodiment, the reservoir is equipped with a LiCl-LiCl precursor inlet located towards the top of the reservoir. This inlet allows for the addition of LiCl, its precursor, or a mixture thereof (preferably LiCl, or a mixture of LiCl and precursor, more preferably LiCl, or alternatively LiCl precursor) to a bath of LiCl in the reservoir to replenish the electrolytic medium. The LiCl / precursor / mixture can be in powder form (i.e., cryogenic) or liquid form, preferably in powder form. In an embodiment where a precursor is used, LiCl is produced from the precursor in the cell. In an embodiment, the precursor is lithium oxide, lithium carbonate, and / or a lithium salt other than LiCl, preferably lithium oxide or lithium carbonate, more preferably lithium oxide.

[0056] In a preferred embodiment, chlorine gas is bubbled into a bath of LiCl in the reservoir. In such an embodiment, LiCl is generated from a precursor in the reservoir. Thus, in such an embodiment, the device further comprises a chlorine bubbler in the reservoir. The reservoir is also equipped with a gas outlet that allows removal of by-product gases such as O2 and / or CO2 generated by the ongoing chemical reaction, which may be, for example: 2Li2CO3+2Cl2→4LiCl+2CO2+O2 2Li2O+2Cl2→4LiCl+O2

[0057] Preferably, the chlorine gas produced by the electrolysis cell is used to produce LiCl in the reservoir. In a preferred such embodiment, a fourth conduit fluidly connects a chlorine gas outlet of the cell with a chlorine bubbler in the reservoir.

[0058] In embodiments, when LiO is used as the LiCl precursor added to the reservoir (either alone or in a mixture with LiCl), the LiO is added (as described above) For example, by dehydration of lithium hydroxide (2LiOH→Li2O+H2O) in a dehydration reactor, or For example, it can be produced either by decarbonation of lithium carbonate (Li2CO3 → Li2O + CO2) in a decarbonation reactor. Such reactors are discussed further below. In a more preferred embodiment, LiCl or a LiCl-Li2O mixture is produced by the chlorination of lithium oxide in a chlorination reactor and then added to the reservoir.

[0059] Thus, in an embodiment, the apparatus comprises: a chlorination reactor for the chlorination of LiO to LiCl or a LiCl-LiO mixture, the chlorination reactor being equipped with a chlorine gas inlet, an oxygen gas outlet, a LiO inlet and a LiCl / LiCl-LiO mixture outlet, and optionally equipped with a heating element; a fifth conduit connecting the LiCl / LiCl-Li2O mixture outlet of the chlorination reactor to either the LiCl / LiCl precursor inlet of the reservoir or to the electrolyte medium inlet of the cell. This fifth conduit allows the LiCl or LiCl-Li2O mixture to be discharged from the chlorination reactor to a reservoir or cell. The LiCl or LiCl-Li2O mixture discharged by the fifth conduit may be solid or liquid, preferably solid.

[0060] In an embodiment, the temperature in the chlorination reactor is controlled as known in the art.

[0061] Preferably, the chlorine gas produced by the electrolysis cell is used to produce a LiCl / LiCl-Li2O mixture in the chlorination reactor. In a preferred such embodiment, the sixth conduit fluidly connects the chlorine gas outlet of the cell and the chlorine gas inlet of the chlorination reactor.

[0062] In an even more preferred embodiment, the LiO reactant for the chlorination reactor is For example, by dehydration of lithium hydroxide (2LiOH→Li2O+H2O) in a dehydration reactor, or For example, it is produced either by the decarbonation of lithium carbonate (Li2CO3 → Li2O + CO2) in a decarbonation reactor. It is then added to the chlorination reactor.

[0063] Thus, in an embodiment, the apparatus comprises: a dehydration reactor for the production of Li2O from LiOH, the dehydration reactor being equipped with a water vapor outlet, a LiOH inlet, a Li2O outlet, a heating element and a vacuum pump; a seventh conduit connecting the Li2O outlet of the dehydration reactor to the Li2O inlet of the chlorination reactor, to the LiCl / LiCl precursor inlet of the reservoir, or to the electrolyte medium inlet of the cell. This seventh conduit allows the Li2O to be discharged from the dehydration reactor to a chlorination reactor, reservoir, or cell. The Li2O is typically in solid form.

[0064] In an embodiment, the apparatus comprises: - a decarbonation reactor for producing Li2O from Li2CO3, the decarbonation reactor being equipped with a CO2 gas outlet, a Li2CO3 inlet, a Li2O outlet, a heating element and / or a vacuum pump; an eighth conduit connecting the Li2O outlet of the decarbonation reactor to the Li2O inlet of the chlorination reactor, to the LiCl / LiCl precursor inlet of the reservoir, or to the electrolyte medium inlet of the cell. This eighth conduit allows the Li2O to be discharged from the decarbonation reactor to a chlorination reactor, reservoir or cell. The Li2O is typically in solid form.

[0065] The advantage of these embodiments is that the CO2 produced is pure enough (not mixed with O2 and has traces of Cl2) to be used in many applications.

[0066] Additionally, embodiments including Li2CO3 have the advantage of reducing costs, as Li2CO3 is a form of lithium that is easily extracted by current mining processes.

[0067] In embodiments, the temperature / pressure in the dehydration reactor and the decarbonation reactor may be controlled in a manner known in the art.

[0068] All of the above embodiments involving a chlorination reactor or chlorination in the reservoir have the advantage of producing higher purity lithium metal, since they avoid the introduction of Li2CO3 into the electrolysis cell (as taught in the prior art). Indeed, in preferred embodiments, the electrolysis medium is free of lithium carbonate, and preferably free of lithium oxide and lithium carbonate.

[0069] The alkali halide, when used in the electrolytic medium, may be added to the reservoir by an inlet facing the top of the reservoir or by a separate inlet provided within the reservoir.

[0070] The electrolytic cell is a membrane-free cell of the type known in the art, for example as described above. It can be operated according to parameters known in the art. The electrolytic cell can be, for example, as described in US 4,724,055 and US 4,740,279. In an embodiment, in the electrolytic cell, a steel cathode is welded to the bottom of a closed cylindrical steel vessel, and a vertical graphite anode has a portion sealed from the atmosphere, surrounded by the cathode, and immersed in molten LiCl.

[0071] The anode is preferably made of graphite, is cylindrical (e.g. a rod) and may be covered (by a material such as alumina, quartz, silica, etc.) in the parts that are not immersed in the electrolytic medium to a certain depth below the interface between the electrolytic medium and the gas phase.

[0072] The cathode is preferably cylindrical and may be attached to the wall of the cell by any means which does not impede the circulation of the electrolytic medium and which provides electrical conduction.

[0073] The same potential is applied to the cathode and the cell container. The negative terminal of a voltage source is connected to the bottom of the cell container.

[0074] If desired, flow in any one of the first through eighth conduits may be facilitated by a pump as known to those skilled in the art.

[0075] How to use a liquid-liquid separator Also provided is a method for producing lithium, the method comprising: a) electrolyzing an electrolysis medium containing molten LiCl in a membrane-free electrolysis cell; b) collecting a mixture of lithium metal and electrolytic medium from the cell; and c) combining or separating lithium metal from the mixture using a liquid-liquid separator, wherein the liquid-liquid separator comprises at least one film coalescer or at least one centrifuge.

[0076] The liquid-liquid separator, film coalescer, centrifuge, electrolysis medium, and electrolysis cell (including the anode and cathode) are as described in the previous section.

[0077] In an embodiment, the method further comprises the step of supplying LiCl, a precursor thereof, or a mixture thereof (preferably LiCl, or a mixture of LiCl and a precursor, more preferably LiCl, or alternatively a LiCl precursor) to the cell. In a preferred embodiment, the LiCl, a precursor thereof, or a mixture thereof supplied to the cell is held in an electrolytic medium reservoir prior to being supplied to the cell. In an embodiment, the precursor is lithium oxide, lithium carbonate, and / or a lithium salt other than LiCl, preferably lithium oxide or lithium carbonate, more preferably lithium oxide.

[0078] In an embodiment, the method further comprises collecting the liquid stream produced by the liquid-liquid separator in a collection tank, the stream comprising Li metal and electrolytic medium, allowing the stream to be decanted into a phase of Li metal above a phase of electrolytic medium. In an embodiment, the stream is allowed to drop into the collection tank.

[0079] In an embodiment, the method further comprises recycling the electrolysis medium from the liquid-liquid separator or from a collection tank within the cell or in the electrolysis medium reservoir. Preferably, the electrolysis medium from the collection tank is recycled in the electrolysis medium reservoir.

[0080] In an embodiment, the method further comprises using heat from the cell to heat the separator (and collection tank, if present) and / or the reservoir. In a preferred embodiment, the liquid-liquid separator (and collection tank, if present) is enclosed within the separation chamber. Preferably, the separation chamber is located immediately adjacent to the electrolysis cell. In an embodiment, the separation chamber is located between the electrolysis medium reservoir and the electrolysis cell and immediately adjacent to the electrolysis medium reservoir and the electrolysis cell. The cell, separation chamber, and reservoir may be in parallel, as shown in FIG. 8, or preferably circumferentially enclosed with the cell inside, as shown in FIG. 9. Additional heating elements may be provided to heat the separation chamber and / or the electrolysis medium reservoir, if desired.

[0081] In an embodiment, the method further comprises adding LiCl, a precursor thereof, or a mixture thereof (preferably LiCl, or a mixture of LiCl and a precursor, more preferably LiCl, or alternatively a LiCl precursor) to the bath of LiCl in the reservoir to replenish the electrolytic medium. In an embodiment, the precursor is lithium oxide, lithium carbonate, and / or a lithium salt other than LiCl, preferably lithium oxide or lithium carbonate, more preferably lithium oxide.

[0082] In an embodiment, LiCl is added to the reservoir in powder form (cold) or liquid form, preferably in powder form.

[0083] In an embodiment, the precursor added to the reservoir or cell is lithium oxide alone or in a mixture with LiCl.

[0084] In a preferred embodiment, the method further comprises producing LiCl from a precursor in the reservoir. In an embodiment, the method further comprises bubbling chlorine in the reservoir. Preferably, a gas bubbler is used to bubbling the chlorine. Preferably, the method comprises using chlorine gas produced in the cell to bubble in the reservoir.

[0085] In an embodiment, the method further comprises the step of producing LiCl or a LiCl-Li2O mixture by chlorination of lithium oxide, and then adding the LiCl or LiCl-Li2O mixture to a reservoir or cell. Preferably, the method comprises the step of using chlorine gas produced in the cell to chlorinate the lithium oxide. In an embodiment, the temperature of the chlorination reactor is controlled as known in the art. When the reaction is incomplete, some unreacted Li2O remains, resulting in a LiCl-Li2O mixture. This is not harmful, since Li2O does not react with Li metal, contrary to Li2CO3.

[0086] In a more preferred embodiment, the method further comprises the step of producing Li2O by dehydration of lithium hydroxide or decarbonation of lithium carbonate.

[0087] An advantage of the embodiment involving the decarbonation of lithium carbonate to lithium oxide is that the CO produced is of sufficient purity (not mixed with O and with traces of Cl) to be used in many applications. In embodiments, the temperature / pressure for dehydration and decarbonation can be in a manner known in the art.

[0088] The above process involving lithium carbonate has the advantage of reducing costs because Li2CO3 is a form of lithium that is easily extracted by current mining processes.

[0089] All of the above embodiments involving chlorination of the precursor (in the reservoir or prior to being added to the reservoir) have the advantage of producing higher purity lithium metal, since they avoid the introduction of Li2CO3 into the electrolysis cell (as taught in the prior art). Indeed, in preferred embodiments, the electrolysis medium is free of lithium carbonate, and preferably free of lithium oxide and lithium carbonate.

[0090] In some of the above embodiments, some lithium oxide and / or lithium carbonate may remain in the LiCl. In preferred embodiments, the electrolytic medium is free of lithium carbonate, and preferably free of lithium oxide and lithium carbonate.

[0091] When an alkali halide is used in the electrolysis medium, the method further comprises the step of adding the alkali halide to the reaction mixture.

[0092] Method for producing lithium metal from Li2O In another aspect of the invention, a method for producing lithium metal from LiO is provided, the method comprising: 1. providing i) LiO, ii) LiCl generated from LiO, or iii) a mixture thereof to an electrolysis cell, the electrolysis cell comprising an anode, a cathode, and an electrolysis medium comprising molten LiCl; 2. Electrolyzing molten LiCl in the electrolytic cell to produce Li metal and chlorine gas.

[0093] This aspect of the invention is based on the chlorination of lithium oxide, the following chemical reaction: 2Li2O+2Cl2→4LiCl+O2.

[0094] In embodiments where Li2O is provided to the cell in step 1), the method includes producing LiCl directly in the cell using the chlorine gas produced in step 2), which LiCl is then electrolyzed in step 2) to produce Li metal.

[0095] In an embodiment, the method includes first chlorinating Li2O to produce LiCl, and then feeding LiCl to the cell in step 1). When this reaction is incomplete, some unreacted Li2O remains and a LiCl-Li2O mixture is obtained and fed to the reactor. This is not harmful because, contrary to Li2CO3, Li2O does not react harmfully with Li metal.

[0096] In an embodiment, the chlorinating may occur in a chlorination reactor.

[0097] In a preferred embodiment, the method comprises bubbling chlorine through a bath of molten LiCl containing LiO and then feeding the resulting LiCl (with or without residual LiO) to an electrolytic cell. Preferably, a gas bubbler is used to bubble the chlorine. Preferably, the method uses chlorine gas produced by the cell for said bubbling.

[0098] In an alternative preferred embodiment, the method includes using chlorine gas to chlorinate solid LiO and then feeding the resulting LiCl (with or without residual LiO) to an electrolytic cell. Preferably, the method uses the chlorine gas produced by the cell to chlorinate the solid LiO.

[0099] The electrolysis cell can be a diaphragm-less electrolysis cell as described in the previous section, or an electrolysis cell with a diaphragm as taught in the prior art.

[0100] It should be noted that the use of Li2O is advantageous because, contrary to Li2CO3, Li2O does not react undesirably with Li metal. It is also less hygroscopic than LiCl and therefore easier to use. In short, the disadvantages of using LiCl or Li2CO3 as mentioned above are avoided.

[0101] In a more preferred embodiment, the method further comprises the step of producing Li2O by dehydration of lithium hydroxide or decarbonation of lithium carbonate.

[0102] definition In the context of describing the present invention (particularly in the context of the claims which follow), the use of the terms "a," "an," and "the" and similar referents are to be construed to encompass both the singular and the plural, unless otherwise indicated in the specification or clearly contradicted by context.

[0103] The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to") unless otherwise noted. In contrast, the phrase "consisting of" excludes any unspecified elements, steps, ingredients, etc. The phrase "consisting essentially of" limits the scope to certain materials or steps and those that do not materially affect the basic and novel feature(s) of the invention.

[0104] The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within that range, unless otherwise stated herein, and each separate value is incorporated herein as if it were individually set forth herein. Every subset of values ​​within a range is also incorporated herein as if it were individually recited herein.

[0105] All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted by context.

[0106] The use of any and all examples or exemplary language (e.g., "etc.") described herein is intended merely to better clarify the invention and does not limit the scope of the claims unless otherwise specified.

[0107] No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0108] As used herein, the term "about" has its ordinary meaning. In embodiments, "about" may mean plus or minus 10% or plus or minus 5% of the qualified numerical value.

[0109] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0110] Other objects, advantages and features of the present invention will become more apparent upon reading of the following non-restrictive description of specific embodiments, given by way of example only with reference to the accompanying drawings.

[0111] Description of exemplary embodiments The invention is illustrated in further detail by the following non-limiting examples. EXAMPLES

[0112] Example 1 FIG. 10 is a cross-sectional view of device (8) according to an embodiment of the present invention.

[0113] The separation chamber (20) between the undivided (non-diaphragm) electrolysis cell (10) and the electrolysis media reservoir (30) is shown. The cell (10) includes an anode (12), a cathode (14), a Cl2 gas outlet (16), and a Li metal / electrolysis media mixture outlet (18). The separation chamber (20) includes a single plate film coalescer (22) connected to the media mixture outlet (18) and located above a collection tank (24). The reservoir (30) is connected to the cell (10) by a "first conduit" (32) located below the separation chamber (20). The reservoir (30) is also connected to the separation chamber (20) through a second conduit (26). The flow in the second conduit (26) is quiet thanks to a vertical baffle (27). The second conduit (26) terminates in an overflow outlet (28), the height of which can be adjusted to control the liquid level in the collection tank (24). The reservoir (30) is equipped with a LiCl / LiCl precursor inlet (34) (allowing for the introduction of LiCl and / or precursors of LiCl such as Li2O or Li2CO3), a gas outlet (40) and a chlorine bubbler (36) connected to the Cl2 gas outlet (16) by a "fourth conduit" (38). The separation chamber is equipped with a lithium metal outlet (29) for collecting the produced Li metal.

[0114] In use, the cathode (14) is fully immersed in an electrolytic medium containing LiCl. Chlorine bubbles are generated at the anode (12) and Li metal droplets are produced at the cathode (14). Chlorine gas is captured at the top of the cell (10) and bubbled into a reservoir (30). The reservoir (30) holds the electrolytic medium (containing liquid LiCl) to which LiCl precursor (here lithium oxide or lithium carbonate) is added via a LiCl / LiCl precursor inlet (34). This produces LiCl, which is delivered to the cell by a "first conduit" (32). A mixture of Li metal and LiCl is collected from the surface of the electrolytic medium in the cell (10) via a Li metal / electrolytic medium mixture outlet (18). The Li metal in this mixture is coalesced with a single plate film coalescer (22). The electrolytic medium with the coalesced Li metal droplets falls into a decantation tank where it separates into two phases and the Li-droplet-free electrolytic medium is recycled through a second conduit (26) to the reservoir (30). The Li metal collected in the decantation tank can be recovered through a lithium metal outlet (29).

[0115] Example 2 FIG. 11 shows an apparatus (100) similar to the apparatus (10) shown in FIG. 10, except that the reservoir (30) is equipped with a LiCl / LiCl precursor inlet (102) and the apparatus further comprises a chlorination reactor (200) for producing LiCl or a LiCl-LiO mixture from LiO, and a decarbonation reactor (300) (heated and / or under vacuum) for producing LiO from LiCO.

[0116] The chlorination reactor (200) has a LiCl / LiCl-Li2O mixture outlet (202) connected to the LiCl / LiCl precursor inlet (102) of the reservoir (30) by a "fifth conduit" (104). The chlorination reactor (200) is equipped with a chlorine gas inlet (204) connected to the Cl2 gas outlet (16) of the cell (10) by a "sixth conduit" (106). The chlorination reactor (200) is further equipped with an oxygen gas outlet (206) and a Li2O inlet (208).

[0117] The decarbonation reactor (300) is equipped with a LiO outlet (302) connected to the LiO inlet (208) of the chlorination reactor (200) by a "seventh conduit" (108) for carrying LiO from the decarbonation reactor (300) to the chlorination reactor (200). The decarbonation reactor (300) is further equipped with a CO gas outlet (304) and a LiCO inlet (306).

[0118] During use, LiCl or a LiCl-Li2O mixture is added to the reservoir (30). The LiCl or LiCl-Li2O is produced from Li2O in the chlorination reactor (200). Chlorine gas captured at the top of the electrolysis cell (10) is sent to the chlorination reactor (200), while the produced oxygen is removed from the chlorination reactor (200) via the oxygen outlet (206). The Li2O is produced by decarbonating Li2CO3 in the decarbonation reactor (300). The produced CO2 is removed from the decarbonation reactor (300) via the CO2 gas outlet (304).

[0119] Example 3 FIG. 12 shows an apparatus (400) similar to the apparatus (100) shown in FIG. 11, except that the LiO for the chlorination reactor is produced by dehydrating LiOH in a dehydration reactor (500) (which is heated and / or under vacuum) rather than in a decarbonation reactor (300).

[0120] The dehydration reactor (500) is equipped with a LiO outlet (502) connected to the LiO inlet (208) of the chlorination reactor (200) by an "eighth conduit" (402). The dehydration reactor (500) is further equipped with a water vapor outlet (504) and a LiOH inlet (506).

[0121] In use, Li2O for the chlorination reactor (200) is produced by dehydration of Li2CO3 in the dehydration reactor (500). The water vapor produced is removed from the dehydration reactor via the water vapor outlet (504).

[0122] Example 4 To demonstrate the effectiveness of the single plate film coalescer (22) for the separation of liquid Li droplets from liquid electrolyte (see FIG. 10 and Example 1), the apparatus of FIG. 10 was fabricated in polycarbonate. The apparatus had three compartments depicted in FIG. 10: the electrolysis cell (10), the separation chamber (20), and the electrolysis medium reservoir (30). The electrolysis cell (10) was a cylinder (

number

[0123] For the experiments, a 1.49 g / cm3 sintered body was used (density at room temperature is 1.49 g / cm3). 3 A 47% K2CO3 solution was used to simulate the LiCl-KCl (53%-47%) eutectic mixture with a density of 1.64 at 450 °C in a conventional Li-producing electrolytic cell (density at room temperature is 0.857 g / cm3). 3Mineral oil (0.1% NaOH) was used to simulate liquid Li in the cell. A small amount of β-carotene was added to the mineral oil to impart a yellow to orange color, facilitating visual observation of the oil behavior that was simulating the Li droplets.

[0124] A peristaltic pump was used to add mineral oil at a controlled rate to the line where the liquid was pumped from the bottom of the reservoir (30) to the bottom of the electrolytic cell (10). To simulate the creation of small droplets of molten Li mixed with the LiCl-KCl electrolyte between the cathode and anode spaces (a membrane-less electrolytic cell operating in gas lift mode), an in-line mixer was installed in the pipe (first conduit 32) before the inlet at the bottom of the electrolytic cell (10) to create very small mineral oil droplets in the K2CO3 solution. Two types of experiments were performed.

[0125] In the first experiment, a single plate coalescer (22) 300 mm wide and 330 mm long was placed approximately horizontally (at a slight downward angle to create a 0.35 mm height of liquid above the plate) at the outlet (18) between the electrolytic cell (10) and the separation chamber (20). The K2CO3 solution was recirculated at a constant flow rate of 2 liters / min from the bottom of the reservoir (30) through the first conduit (32) to the bottom of the electrolytic cell (10). 1.5 liters of mineral oil were added to the separation chamber to create a 15 mm layer floating on top of the K2CO3 solution, simulating the accumulated molten Li generated in the electrolytic cell. Mineral oil was then added at a constant rate of 1.3 g / min to the K2CO3 solution in the recirculation line (32). Fine mineral oil droplets created in the in-line mixer rose in the electrolytic cell (10), simulating the rise of fine Li droplets created on the cathode, and were pushed upwards by chlorine bubbles generated at the anode. The mixture of mineral oil droplets and K2CO3 solution constantly overflowed from the outlet (18) of a single coalescer plate (22). The angle of the coalescer plate (22) was adjusted to create a thin film of liquid about 0.35 mm high, resulting in a residence time of nearly 1 second on the coalescer plate (22). The experiment was run for 6 hours, during which 467 g of mineral oil was added to the bottom of the electrolytic cell (10). At the same time, mineral oil was collected at the lithium metal outlet (29), simulating the collection of Li separated in the electrolytic cell operating at about 200 A with a current efficiency of 85%. After 6 hours of recirculation and oil addition, the K2CO3 solution in the reservoir chamber (30) had an opaque appearance and the presence of mineral oil was visible on the surface. In order to obtain a completely clear and transparent K2CO3 solution in the reservoir (30), it was necessary to wait a decantation period of 68 hours. At this time, the oil floating on the surface was collected and weighed using an oil-selective absorbent. The weight of the oil collected after 68 hours (after correction for the small amount of K2CO3 solution absorbed by the oil-selective absorbent) was 35.61 g, which corresponds to 7.6% of the total oil added to the system by the peristaltic pump.

[0126] In the second experiment, the plates of the single plate coalescer were removed and replaced with a 2-inch diameter tube of the same length as the plates of the single plate coalescer. The rest of the experiment with respect to the setup and recirculation rate of the K2CO3 solution was the same as the first experiment, except for a slightly lower mineral oil addition rate of 1 g / min (instead of 1.3 g / min in the first experiment). The experiment was run for 6 hours, during which 360 g of mineral oil was added to the bottom of the electrolytic cell (10). At the same time, mineral oil was collected at the lithium metal outlet (29). After 6 hours of recirculation and oil addition, the K2CO3 solution in the reservoir (30) had an opaque appearance, and the presence of mineral oil on the surface was very easy to see. After a decantation period of 68 hours, the K2CO3 solution in the reservoir (30) was still opaque (contrary to the first experiment with the coalescer plate, where the solution was completely clear). At this time, the oil floating on the surface was collected and weighed using an oil-selective absorbent. The weight of the oil collected after 68 hours (after correction for the small amount of K2CO3 solution absorbed by the oil-selective absorbent) was 66,26 g, corresponding to 18,4% of the total oil added to the system by the peristaltic pump. To obtain a clear K2CO3 solution in the reservoir (30), it was necessary to wait 120 hours of decantation, recovering another 6,87 g of oil, bringing the total amount of oil not recovered by the separation chamber (20) to 73,15 g, corresponding to 20,29% of the total oil added by the peristaltic pump in the experiment.

[0127] As is evident, the use of a simple liquid-liquid thin film coalescer made it possible to significantly reduce the percentage of oil that was not collected in the quiet zone of the separation chamber (20), as it decreased from 20.29% to 7.6%, despite the fact that in the first experiment more oil was added (1.3 g / min compared to 1.0 g / min). The effectiveness of the coalescer is also evident from the time needed to obtain a completely clear solution in the reservoir (30), which decreased from 120 to 68 hours after the installation of the coalescer plate. The results are consistent with the results for the LiCl-KCl eutectic mixture (1.64 g / cm). 3 ) of molten Li (0,490g / cm 3It should be noted that the density ratio of Li to LiO is 3.35:1 at 450°C, compared to 1.74:1 for 47% K2CO3 solution and mineral oil at 20°C. For molten Li in the eutectic mixture, a higher ratio may result in even better separation efficacy than that obtained in this example.

[0128] Example 5 5,066 kg of LiCl-KCl eutectic mixture was prepared by mixing 2,295 kg LiCl and 2,771 kg KCl powder. Then 100 g of Li2O powder with 99,5% purity was thoroughly mixed with the LiCl-KCl salt. The mixture was placed in a stainless steel cylindrical chlorination reactor equipped with stainless steel walls and a 99,5% alumina lining covering the bottom. The reactor has an inner diameter of 100 mm and a total height of 813 mm. The reactor cover was equipped with a 1 / 4 inch tube Ar inlet that extended all the way to the bottom of the reactor, a stainless steel thermocouple, a gas sparger consisting of a 1 / 2 inch stainless steel closed end tube with several 1 mm outlet holes at the end of the tube, and a 1 / 2 inch gas outlet. A grafoil disk was used as a gasket to seal the reactor. The reactor containing the mixture was placed in a furnace and heated at 300 °C overnight under Ar atmosphere to remove residual water, especially from the LiCl. The temperature was then raised to 400 °C to melt the mixture, obtaining a typical liquid eutectic mixture of 45,3% LiCl and 54,7% KCl, used in Li-producing electrolytic cells. The molten salt had a total height of 380 mm in the reactor. Salt samples were taken from the top 120 mm of the liquid by the introduction of a 1 / 4 stainless steel rod (previously heated to 105 °C to remove residual moisture). At each sampling, about 3 g of solidified salt was taken. To proceed to analysis, each sample was collected in a glass vial filled with Ar. The samples were then quickly ground to a homogenous powder and accurately weighed (0,2-2 g, depending on the residual concentration of Li2O). The samples were dissolved in ultrapure water and titrated using a certified 0,01 N HCl solution to determine the residual amount of Li2O (which, once dissolved in water, is titrated against HCl as LiOH). It was determined that the intensity of the stirring created by the Ar bubbles affected the concentration of Li2O measured in the top 120 mm of the reactor. However, even with Ar bubbling at rates up to 5 l / min, the highest Li2O concentration measured was 1,72%, compared to the 1,92% expected by adding 100 g of 99,5% Li2O to 5066 g of LiCl-KCl.In the experiment, Cl2 gas (99.5%) was bubbled through the sparger at a flow rate of 3 l / min, and 2 l / min of Ar was bubbled through the Ar bubbler to keep the Li2O particles in suspension. In this experiment, the first sample was taken after 30 min of Cl2 bubbling, and the residual Li2O particles were i2 The Li2O concentration was 0,04%, corresponding to a conversion of 97,7%. The chlorination was continued for another 10 min until the Li2O concentration reached 0,005%, corresponding to a conversion of 99,7%. The final sample of this experiment was taken after 10 min for a total chlorination of 50 min, but the Li2O conversion remained unchanged at 99,7%.

[0129] The second experiment was carried out by adding 100 g Li2O to the mixture obtained at the end of chlorination experiment 1. For this, 100 g Li2O was mixed with 282 g KCl (to compensate for the conversion of Li2O to LiCl in the first experiment and to balance the LiCL:KCl ratio) and 30 g KCl-LiCl mixture (to compensate for sampling losses). The initial Li2O concentration measured in the top 120 mm of the reactor mixture was 1,46% instead of the expected 1,72% (99,5 g Li2O out of 5768 g mixture). Such a lower initial ratio is most likely related to the addition of the powder mixture to the reactor, resulting in a partial deposition of Li2O on the reactor walls above the liquid level. With regard to the conditions of experiment 1, the chlorination in experiment 2 was carried out with 3 l / min Cl2 through the chlorine sparger and 2 l / min Ar through the argon bubbler. This time samples were taken every 10 min for a total of 50 min of chlorination. The results of both chlorination experiments are shown in Figure 13. The conversion obtained after 50 min was 99.4% with a very low residual Li2O concentration of 0.009%.

[0130] These results clearly demonstrate the feasibility of continuously adding Li2O as a Li precursor and converting it to LiCl at very practical rates and with very low residual Li2O concentrations. Note that using Li2O as a Li precursor has an important advantage over Li2CO3 because, contrary to Li2CO3, Li2O does not react with Li metal and therefore 100% conversion is not required.

[0131] The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be accorded the broadest interpretation consistent with the description as a whole.

[0132] References This description makes reference to several documents, the contents of which are incorporated herein by reference in their entirety. These documents include, but are not limited to, the following: Published European Patent Publication No. 107 521 Published French Patent Application No. 2,532,332 Published French Patent Application No. 2,560,221 US$1,501,756 US2,968,526 ·US2013 / 0001097A1 US3,085,967 US$3,344,049 US$3,560,263 US$3,962,064 US4,139,428 US$4,200,686 US4,405,416 US4,533,442 US$4,617,098 US4,724,055 US4,740,279 US4,980,136 US4,988,417 and WO2020 / 210913 ·Thermal Properties of LiCl-KCl Molten Salt for Nuclear Waste Separation, Lithium properties and interactions(1978) ·Jeppson et al.,Lithium Leterature Review:Lithium’s properties and interactions.Hanford Engineering Development Laboratory,April 1978

Claims

1. 1. An apparatus for producing lithium metal by electrolysis, said apparatus comprising: A liquid-liquid separator; and a membrane-free electrolysis cell, the membrane-free electrolysis cell comprising: an anode and a cathode immersed in an electrolytic medium comprising molten LiCl; a chlorine gas outlet located at an upper portion of the cell; a Li metal / electrolytic medium mixture outlet adjacent a surface level of the electrolytic medium within the cell, the mixture outlet being in fluid communication with the liquid-liquid separator to permit passage of a mixture of the electrolytic medium and lithium metal produced by the electrolytic cell into the liquid-liquid separator; the liquid-liquid separator comprising at least one film coalescer or at least one centrifuge for separating the lithium metal produced by the electrolytic cell from the electrolytic medium.

2. 2. The apparatus of claim 1, wherein the liquid-liquid separator comprises at least one film coalescer, preferably the liquid-liquid separator comprises at least two or more film coalescers in series.

3. 3. An apparatus according to claim 1 or 2, wherein the liquid-liquid separator comprises at least one centrifuge, preferably the liquid-liquid separator comprises two or more centrifuges in series.

4. An apparatus according to any one of claims 1 to 3, wherein the liquid-liquid separator comprises at least one film coalescer in series with at least one centrifuge.

5. 5. An apparatus according to any one of claims 1 to 4, wherein the film coalescer(s) is / are a plate separator and / or a packed bed column, preferably the film coalescer(s) is / are a plate separator.

6. Apparatus according to any one of claims 1 to 5, wherein the centrifuge(s) are cyclones and / or centrifugal separators, preferably the centrifuge(s) are cyclones.

7. 7. Apparatus according to any one of claims 1 to 6, wherein the electrolytic medium further comprises molten lithium oxide, molten lithium carbonate and / or molten alkali halide (preferably molten alkali chloride, more preferably molten KCl).

8. The apparatus of any one of claims 1 to 7, wherein the cell further comprises an electrolyte medium inlet facing towards a base of the cell.

9. 9. The apparatus of any one of claims 1 to 8, further comprising an electrolysis medium reservoir and a first conduit fluidly connecting a base of the reservoir to the base of the cell.

10. 10. The apparatus of claim 9, wherein the reservoir is equipped with a LiCl / LiCl precursor inlet located toward the top of the reservoir.

11. 11. The apparatus of claim 9 or 10, further comprising a chlorine bubbler in the reservoir.

12. 12. The apparatus of claim 11, further comprising a fourth conduit fluidly connecting the chlorine gas outlet of the cell and the chlorine bubbler in the reservoir.

13. Apparatus according to any one of claims 9 to 12, wherein the reservoir is equipped with a gas outlet for removal of by-product gases.

14. 14. The apparatus of any one of claims 1 to 13, further comprising a collection tank for collecting a stream of liquid comprising Li metal produced by the liquid-liquid separator.

15. The apparatus of claim 14 , wherein the collection tank is located below the liquid-liquid separator.

16. 16. Apparatus according to claim 14 or 15, further comprising a second conduit fluidly connecting the collection tank to the reservoir, preferably said second conduit terminating at a desired height relative to the level of electrolysis medium in the collection tank.

17. 17. The apparatus of any one of claims 14 to 16, wherein the collection tank comprises a lithium metal outlet for discharging the produced lithium metal.

18. Apparatus according to any one of the preceding claims, wherein the liquid-liquid separator (and the collection tank, if present) are enclosed within a separation chamber, preferably immediately adjacent to the electrolysis cell.

19. 20. The apparatus of claim 18, wherein the liquid-liquid separator is located between and immediately adjacent the electrolysis medium reservoir and the electrolysis cell.

20. LiCl or LiCl-Li ２ Li to O mixture ２ A chlorination reactor for the chlorination of O, comprising a chlorine gas inlet, an oxygen gas outlet, and a Li ２ O inlet and LiCl / LiCl-Li ２ a chlorination reactor equipped with an O mixture outlet and a heating element; The LiCl / LiCl-Li ２ and a fifth conduit connecting an O mixture outlet to either the LiCl / LiCl precursor inlet of the reservoir or the electrolyte medium inlet of the cell.

21. 21. The apparatus of claim 20, further comprising a sixth conduit fluidly connecting said chlorine gas outlet of said cell and said chlorine gas inlet of said chlorination reactor.

22. Li from LiOH ２ A dehydration reactor for the production of O, comprising a water vapor outlet, a LiOH inlet, and a Li ２ a dehydration reactor equipped with an O outlet and a heating element and / or a vacuum pump; The Li of the dehydration reactor ２ The Li outlet of the chlorination reactor is connected to the O outlet. ２ 22. The apparatus of claim 1, further comprising: a seventh conduit connecting to an O inlet, the LiCl / LiCl precursor inlet of the reservoir, or the electrolyte medium inlet of the cell.

23. Li ２ CO ３ From Li ２ A decarbonation reactor for producing CO ２ A gas outlet and Li ２ CO ３ The entrance and Li ２ a decarbonation reactor equipped with an O outlet and a heating element and / or a vacuum pump; The Li of the decarbonation reactor ２ The Li outlet of the chlorination reactor is connected to the O outlet. ２ and an eighth conduit connecting to an O inlet, the LiCl / LiCl precursor inlet of the reservoir, or the electrolyte medium inlet of the cell.

24. 1. A method for producing lithium, the method comprising: a) electrolyzing an electrolysis medium containing molten LiCl in a membrane-free electrolysis cell; b) collecting a mixture of lithium metal and electrolytic medium from said cell; c) combining or separating lithium metal from said mixture using a liquid-liquid separator, said liquid-liquid separator comprising at least one film coalescer or at least one centrifuge.

25. 25. The method of claim 24, wherein the liquid-liquid separator comprises at least one film coalescer, preferably the liquid-liquid separator comprises at least two or more film coalescers in series.

26. 26. A method according to claim 24 or 25, wherein the liquid-liquid separator comprises at least one centrifuge, preferably the liquid-liquid separator comprises at least two or more centrifuges in series.

27. 27. The method of any one of claims 24 to 26, wherein the liquid-liquid separator comprises at least one film coalescer in series with at least one centrifuge.

28. 28. The method according to any one of claims 24 to 27, wherein the film coalescer(s) is / are a plate separator and / or a packed bed column, preferably the film coalescer(s) is / are a plate separator.

29. The method according to any one of claims 24 to 28, wherein the centrifuge(s) are cyclones and / or centrifugal separators, preferably the centrifuge(s) are cyclones.

30. 30. The method of any one of claims 24 to 29, further comprising the steps of: supplying molten LiCl, a precursor thereof, or a mixture thereof to the cell; and, when a precursor is supplied, allowing chlorine gas produced by the cell to chlorinate the precursor, thus resulting in molten LiCl.

31. 31. The method of claim 30, further comprising the step of holding the molten LiCl, a precursor thereof, or a mixture thereof in an electrolysis medium reservoir prior to delivering the molten LiCl, a precursor thereof, or a mixture thereof to the cell.

32. 32. The method according to claim 30 or 31, wherein molten LiCl or a mixture of molten LiCl and its precursors (preferably molten LiCl alone) is supplied to the cell.

33. 33. The method of claim 31 or 32, further comprising adding LiCl, precursors thereof, and / or mixtures thereof to a bath of molten LiCl in the electrolysis medium reservoir to replenish the electrolysis medium.

34. 34. The method of any one of claims 31 to 33, further comprising producing molten LiCl from a LiCl precursor in the reservoir.

35. 35. The method of claim 34, wherein the precursor is added to molten LiCl in the reservoir and chlorine gas is preferably bubbled into the reservoir, more preferably using chlorine gas generated in the cell.

36. 37. The method according to any one of claims 30 to 36, wherein the precursor is lithium oxide, lithium carbonate and / or a lithium salt other than LiCl, preferably the precursor is lithium oxide or lithium carbonate, more preferably the precursor is lithium oxide.

37. Chlorination of lithium oxide (preferably using chlorine gas, most preferably using chlorine gas generated in the cell) to give LiCl or LiCl-Li ２ O mixture, and then the LiCl or LiCl-Li ２ 37. The method of any one of claims 30 to 36, further comprising the step of adding an O mixture to the reservoir or cell.

38. Lithium hydroxide is dehydrated or lithium carbonate is decarbonated to Li ２ The method of any one of claims 30 to 37, further comprising the step of generating O.

39. 39. The method of any one of claims 24 to 38, further comprising the step of collecting a liquid stream produced by the liquid-liquid separator, the stream comprising Li metal and the electrolytic medium, allowing the stream to be decanted into a phase of Li metal above a phase of electrolytic medium.

40. 40. The method of any one of claims 24 to 39, further comprising recycling the electrolytic medium from the liquid-liquid separator.

41. The method of any one of claims 24 to 41, further comprising using heat from the cell to heat the separator.

42. Li ２ 1. A method for producing lithium metal from O, the method comprising: 1) i) Li ２ O, ii) Li ２ or iii) a mixture thereof to an electrolysis cell, the electrolysis cell comprising an anode, a cathode, and an electrolysis medium comprising molten LiCl; 2) electrolyzing the molten LiCl in the electrolytic cell to produce Li metal and chlorine gas.

43. Li ２ O is supplied to the cell in step 1), and the chlorine gas generated in step 2) is added to the Li ２ 43. The method of claim 42, wherein said LiCl is capable of reacting with O to produce LiCl, which is then electrolyzed in step 2) to produce Li metal.

44. Li ２ O is chlorinated to produce LiCl, and then Li ２ LiCl produced from O in step 1) is used to remove unreacted Li ２ 43. The method of claim 42, further comprising supplying the cell with or without O.

45. 45. The method of claim 44, wherein the chlorinating is carried out in a chlorination reactor.

46. In the chlorination reactor, Li ２ Chlorine is bubbled into a bath of molten LiCl containing O, and the resulting LiCl is then separated from the unreacted Li ２ 46. ​​The method of claim 44 or 45, comprising feeding the electrolysis cell with or without O.

47. 47. The method of claim 46, wherein a gas bubbler is used to bubble the chlorine.

48. 48. The method according to claim 46 or 47, wherein the chlorine gas produced in step 2) is used for the bubbling in the chlorination reactor.

49. Solid Li using chlorine gas ２ O is chlorinated, and the resulting LiCl is then separated from the unreacted Li ２ 46. ​​The method of claim 44 or 45, comprising feeding the electrolysis cell with or without O.

50. The chlorine gas generated in step 2) is ２ 50. The method of claim 49, used to chlorinate O.

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