Reduction of aluminum by variable and intermittent power supply from renewable energy sources

Abstract

Described herein are low temperature electrochemical methods for producing aluminum metal. The methods generally comprise use of a low-melting electrolyte and a non-alumina feedstock to perform aluminum smelting at temperatures below, e.g., 350 °C. The methods described herein include heating that may be powered by intermittent energy supplies (e.g., intermittent renewable energy sources).

Description

Attorney Docket No: FEG-019WO REDUCTION OF ALUMINUM BY VARIABLE AND INTERMITTENT POWER SUPPLY FROM RENEWABLE ENERGY SOURCES CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No.63 / 657,199, filed on June 7, 2024, and U.S. Provisional Patent Application No.63 / 783,452, filed on April 4, 2025, the disclosure of each of which is hereby incorporated by reference in its entirety for all purposes. BACKGROUND

[0002] Aluminum is a promising candidate for energy storage due to its high energy density, abundance, low cost, non-toxicity, non-volatility, and non-reactivity in storage. One method of extracting the energy from aluminum is to react the aluminum with water to form hydrogen and heat as described in Reaction 1 or Reaction 2. Al + 2 H2O → 1.5 H2+ AlO(OH) + Qreaction(Reaction 1) Al + 3 H2O → 1.5 H2+ Al(OH)3+ Qreaction(Reaction 2)

[0003] Untreated aluminum will typically not react with water due to the highly passivating oxide layer that forms on its surface. However, the oxide layer may be disrupted by an appropriate catalyst, thereby activating the aluminum to make it water-reactive. The ability to readily release the embedded energy stored in aluminum makes aluminum-based energy storage a viable option, including for storage of energy generated using renewable energy sources.

[0004] Aluminum production has been electrified at industrial scales for over 100 years using the Hall-Heroult process. The Hall-Heroult process was a breakthrough in aluminum production, bringing the metal that was once more expensive than gold into common use. However, there are several drawbacks to the process, including high temperature requirements, intolerability to intermittent power supply, and, in many circumstances, high CO2emissions from oxidation of carbon-containing anodes. There is thus a need to develop new processes for aluminum production that avoid these drawbacks. SUMMARY

[0005] Provided herein are methods that accomplish aluminum smelting at reduced temperatures compared to standard aluminum smelting processes, thereby allowing for use of intermittent renewable energy supplies to power the methods. 1 IPTS / 200004774.1Attorney Docket No: FEG-019WO

[0006] In one aspect, provided herein is a low temperature electrochemical method for producing aluminum metal, the method comprising: heating a low-melting electrolyte at or above its melting point in an electrolytic cell, thereby providing molten electrolyte in the electrolytic cell, wherein the electrolytic cell comprises an interior volume and one or more anodes and one or more cathodes, wherein the one or more anodes and one or more cathodes are each disposed within the interior volume, and wherein the molten electrolyte is disposed within the interior volume and is in contact with the one or more anodes and one or more cathodes; dissolving an oxidized aluminum feedstock in the molten electrolyte, thereby forming a molten mixture, wherein the molten mixture is in contact with the one or more anodes and one or more cathodes; reducing oxidized aluminum from the oxidized aluminum feedstock to produce aluminum metal at the one or more cathodes of the electrolytic cell by applying a voltage between the one or more cathodes and one or more anodes, wherein the temperature of the molten mixture is maintained at or above its melting point and equal to or below about 350 °C during the reduction, wherein an electrical current through the molten mixture is produced, wherein the electrical current causes the oxidized aluminum to be reduced at the one or more cathodes to form aluminum metal; and removing the aluminum metal from the electrolytic cell, thereby producing aluminum metal, wherein the melting point of the electrolyte is less than or equal to about 350 °C.

[0007] In another aspect, provided herein is a low temperature electrochemical method for producing aluminum metal, the method comprising: heating a low-melting electrolyte at or above its melting point in an electrolytic cell, thereby providing molten electrolyte in the electrolytic cell, wherein the electrolytic cell comprises an interior volume and one or more anodes and one or more cathodes, wherein the one or more anodes and one or more cathodes are each disposed within the interior volume, and wherein the molten electrolyte is disposed within the interior volume and is in contact with the one or more anodes and one or more cathodes; adding an oxidized aluminum feedstock to the molten electrolyte, wherein the oxidized aluminum feedstock does not dissolve, and wherein the oxidized aluminum feedstock is in contact with the one or more cathodes; 2 IPTS / 200004774.1Attorney Docket No: FEG-019WO reducing oxidized aluminum from the oxidized aluminum feedstock to produce aluminum metal at the one or more cathodes of the electrolytic cell by applying a voltage between the one or more cathodes and one or more anodes, wherein the temperature of the molten electrolyte is maintained at or above its melting point and equal to or below about 350 °C during the reduction, wherein an electrical current through the molten electrolyte is produced, wherein the electrical current causes the oxidized aluminum to be reduced at the one or more cathodes to form aluminum metal; and removing the aluminum metal from the electrolytic cell, thereby producing aluminum metal, wherein the melting point of the electrolyte is less than or equal to about 350 °C.

[0008] In some embodiments, the electrolytic cell further comprises thermal insulation. In some embodiments, the electrolytic cell further comprises an external heating element and / or an internal heating element. In some embodiments, the electrolytic cell comprises housing that is resistant to corrosion, e.g., from molten hydroxides. In some embodiments, the housing comprises PTFE (polytetrafluoroethylene), nickel, and / or PEEK (polyetheretherketone).

[0009] In some embodiments, the method further comprises adding additional oxidized aluminum feedstock to the interior volume of the electrolytic cell to maintain feedstock concentration as oxidized aluminum is consumed. In certain embodiments, the additional oxidized aluminum feedstock is added in batches. In certain embodiments, the additional oxidized aluminum feedstock is added continuously. In certain embodiments, the electrolytic cell is hermetically sealed during addition of the additional oxidized aluminum feedstock. In certain embodiments, the additional oxidized aluminum feedstock is added using a load lock device to prevent exposure of the electrolytic cell to atmosphere.

[0010] In some embodiments, the electrolytic cell is connected to an intermittent energy supply that is used to supply the current and voltage to the electrolytic cell, heat the electrolytic cell, and / or maintain the temperature of the electrolytic cell. In certain embodiments, the intermittent energy supply is a renewable energy source selected from electricity generated by solar panels and electricity generated by wind turbines. In some embodiments, the electrolytic cell is further connected to a second energy supply selected from the group consisting of an electrochemical battery, a heat battery, waste heat from another process, or a combination thereof, wherein the second energy supply sustains the 3 IPTS / 200004774.1Attorney Docket No: FEG-019WO electrolyte in a molten state when the intermittent energy supply is providing low or no power input.

[0011] In some embodiments, the oxidized aluminum feedstock is Al(OH)3, AlOOH, or a mixture of Al(OH)3and AlOOH. In certain embodiments, the oxidized aluminum feedstock is Al(OH)3.

[0012] In some embodiments, the oxidized aluminum feedstock is Al2S3. In certain embodiments, the Al2S3has been produced from a reaction of Al(OH)3and / or AlOOH with sulfur and / or H2S, wherein the Al(OH)3 and / or AlOOH are byproducts of an aluminum-water reaction.

[0013] In some embodiments, the oxidized aluminum feedstock is AlCl3, AlI3, or a mixture of AlCl3and AlI3. In certain embodiments, the oxidized aluminum feedstock is AlCl3. In certain embodiments, the AlCl3 has been produced from a reaction of Al(OH)3 and / or AlOOH with chlorine and / or HCl, wherein the Al(OH)3 and / or AlOOH are byproducts of an aluminum-water reaction. In certain embodiments, the oxidized aluminum feedstock is AlI3. In certain embodiments, the AlI3 has been produced from a reaction of Al(OH)3 and / or AlOOH with iodine and / or HI, wherein the Al(OH)3and / or AlOOH are byproducts of an aluminum-water reaction.

[0014] In some embodiments, the oxidized aluminum feedstock is Al2(SO4)3, KAl(SO4)2, NaAl(SO4)2, or a mixture of Al2(SO4)3 and KAl(SO4)2. In some embodiments, the Al2(SO4)3 has been produced from a reaction of Al(OH)3 and / or AlOOH with SO3, either directly or with H2SO4as an intermediate, wherein the KAl(SO4)2has been produced from a reaction of the Al2(SO4)3 with K2SO4, wherein the NaAl(SO4)2 has been produced from a reaction of the Al2(SO4)3with Na2SO4, and wherein the Al(OH)3and / or AlOOH are byproducts of an aluminum-water reaction.

[0015] In some embodiments, the oxidized aluminum feedstock is at least 95% pure.

[0016] In some embodiments, the low-melting electrolyte is a low temperature molten salt (LTMS) electrolyte based on a binary, ternary, quaternary, or other mixture of chloride and / or other halide (F, Cl, Br, I) salts. In certain embodiments, the LTMS is 41 mole percent AlCl3and 59 mole percent NaCl (melting temperature (Tm)~150 °C). In certain embodiments, the LTMS is 61 mole percent AlCl3and 39 mole percent NaCl (Tm=102 °C). In certain embodiments, the LTMS is 61 mole percent AlF3 and 39 mole percent NaCl. In certain embodiments, the LTMS is 61 mole percent AlI3and 39 mole percent NaCl. In certain embodiments, the LTMS is 61 mole percent AlBr3 and 39 mole percent NaCl. In certain 4 IPTS / 200004774.1Attorney Docket No: FEG-019WO embodiments, the LTMS is about 54.6 mole percent AlCl3, about 19.1 mole percent LiCl, about 19.5 mole percent NaCl, and about 6.8 mole percent KCl (Tm=85 °C). In certain embodiments, the LTMS is about 54.6 mole percent AlF3, about 19.1 mole percent LiCl, about 19.5 mole percent NaCl , and about 6.8 mole percent KCl. In certain embodiments, the LTMS is about 54.6 mole percent AlI3, about 19.1 mole percent LiCl, about 19.5 mole percent NaCl, and about 6.8 mole percent KCl. In certain embodiments, the LTMS is about 54.6 mole percent AlBr3, about 19.1 mole percent LiCl, about 19.5 mole percent NaCl, and about 6.8 mole percent KCl. In some embodiments, the LTMS is about 61 mole percent AlCl3, about 26 mole percent NaCl, and about 13 mole percent KCl.

[0017] In some embodiments, the low-melting electrolyte is a sulfate based electrolyte. In certain embodiments, the sulfate based electrolyte is KAl(SO4)2(Tm=92-95 °C). In certain embodiments, the sulfate based electrolyte is Al2(SO4)3 (Tm= 86.5 °C (octadecahydrate)). In certain embodiments, the sulfate based electrolyte is a binary, ternary, quaternary, or other mixture of sulfate salts, wherein at least one sulfate salt contains aluminum as a working ion.

[0018] In some embodiments, the low-melting electrolyte is a low temperature molten salt (LTMS) electrolyte based on a binary, ternary, quaternary, or other mixture of metal hydroxide compounds. In some embodiments, the LTMS is a binary mixture of NaOH and KOH. In certain embodiments, the LTMS is about 51.5 mole percent NaOH and about 48.5 mole percent KOH. In some embodiments, the LTMS is about 50 mole percent NaOH and about 50 mole percent KOH. In some embodiments, the LTMS is a binary mixture of CsOH and NaOH. In certain embodiments, the LTMS is about 48 mole percent CsOH and about 52 mole percent NaOH (Tm=155 °C). In some embodiments, the LTMS comprises metal cations, and the metal cations have reduction potentials lower than Al3+.

[0019] In certain embodiments, the electrolytic cell is hermetically sealed, thereby preventing evaporation of aluminum-containing salts (e.g., AlCl3).

[0020] In some embodiments, the temperature of the molten electrolyte is maintained at about 100 °C after initial heating. In some embodiments, the temperature of the molten electrolyte is maintained below about 170 °C after initial heating. In some embodiments, the temperature of the molten electrolyte is maintained below about 175 °C after initial heating. In some embodiments, the temperature of the molten electrolyte is maintained below about 200 °C after initial heating. In some embodiments, the temperature of the molten electrolyte is maintained below about 350 °C after initial heating. 5 IPTS / 200004774.1Attorney Docket No: FEG-019WO

[0021] In some embodiments, the one or more anodes are non-carbon anodes that do not emit CO2as an oxidation product.

[0022] In some embodiments, the mass ratio of low-melting electrolyte to oxidized aluminum feedstock compound in the electrolytic cell is about 999:1, 99:1, 95:5, 90:10, 80:20, 75:25, 67:33, or 50:50.

[0023] In some embodiments, removing the aluminum metal from the electrolytic cell comprises periodically removing the one or more cathodes after reducing oxidized aluminum for a specified period of time (e.g., every 1 hour, 12 hours, 1 day, or 1 week), wherein solid aluminum is deposited on the surface of the one or more cathodes. In some embodiments, removing the aluminum comprises heating the electrolytic cell above the melting temperature of aluminum (660 °C), thereby allowing liquid aluminum to flow to the bottom of the electrolytic cell, and removing the liquid aluminum via an outlet at the bottom of the electrolytic cell, or with the assistance of a vacuum, or a combination of both. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG.1A is an image showing heating of a binary salt mixture of 41 mole% AlCl3 (61 wt%) and 59 mole% NaCl (39 wt%) in a stainless steel dish with a butane torch, with a thermocouple used to monitor the temperature of the salt mixture.

[0025] FIG.1B is an image showing hand mixing of the binary salt mixture described in FIG.1A with a spatula.

[0026] FIG.1C is an image showing solidification of the binary salt mixture described in FIG.1A after cooling below its melting point.

[0027] FIG.2A is an image showing addition of 250 mg dried alumina trihydrate (Al(OH)3) to reheated binary salt mixture described in FIG.1A just after addition of the Al(OH)3, with foil added as thermal insulation.

[0028] FIG.2B is an image showing the mixture described in FIG.2A 70 seconds after addition of the Al(OH)3 with moderate stirring. The image shows substantial dissolution and / or dispersion of the Al(OH)3 into the binary salt mixture.

[0029] FIG.3A is a flowchart of an exemplary process for aluminum smelting using Al(OH)3as a feedstock and intermittent renewable energy to power the process. Al(OH)3is added via a load lock system to prevent escape of volatile compounds in the electrolytic cell.

[0030] FIG.3B is a flowchart of an exemplary process for aluminum smelting using Al2S3 as a feedstock and intermittent renewable energy to power the process. The Al2S3 is produced 6 IPTS / 200004774.1Attorney Docket No: FEG-019WO from Al(OH)3that is a byproduct of an aluminum-water reaction. Sulfur generated oxidatively in the electrolytic cell is recycled and used to produce additional Al2S3from Al(OH)3.

[0031] FIG.4A is an image showing an experimental apparatus for oxidized aluminum reduction in an AlCl3 / NaCl / KCl bath. WE = working electrode; CE = counter electrode; RE = reference electrode.

[0032] FIG.4B is a cyclic voltammogram collected from a 61 / 26 / 13 mol% AlCl3 / NaCl / KCl mixture at 150 °C, using platinum coils as the working electrode and counter electrode and aluminum foil as the reference electrode.

[0033] FIG.4C is a graph showing the current over time in a 61 / 26 / 13 mol% AlCl3 / NaCl / KCl mixture at 150 °C, using platinum coils as the working electrode and counter electrode and aluminum foil as the reference electrode, with voltage held at -1V vs. reference.

[0034] FIG.4D is a series of images of an SEM-EDS map of deposits on the platinum cathode after the voltage hold depicted in FIG.4C, including images of oxygen and aluminum contained within the deposits.

[0035] FIG.4E is an SEM-EDS image at 630x magnification showing deposition of various elements on the platinum cathode after the voltage hold depicted in FIG.4C.

[0036] FIG.4F is a series of images of an SEM-EDS image at 7900x magnification showing deposition of various elements on the platinum cathode after the voltage hold depicted in FIG.4C, elemental analysis at two points along the depositions.

[0037] FIG.5A is a graph of a cyclic voltammogram in the NaOH / KOH 50 / 50 mol% electrolyte before and after electrolysis at -3.0 A for 47 minutes. The disappearance of hydrogen and oxygen evolution peaks demonstrates the elimination of dissolved water in the melt.

[0038] FIG.5B is a series of images of an SEM-EDS map of deposits on the working electrode executed at 15 keV after the electrolysis depicted in FIG.5A, including images of oxygen and aluminum contained within the deposits. This series of images demonstrates reduced aluminum deposits.

[0039] FIG.5C is another series of images of an SEM-EDS map of deposits on the working electrode executed at 15 keV after the electrolysis depicted in FIG.5A, including 7 IPTS / 200004774.1Attorney Docket No: FEG-019WO images of oxygen and aluminum contained within the deposits. This series of images demonstrates reduced aluminum deposits.

[0040] FIG.5D is a series of images of an SEM-EDS map of deposits on the working electrode executed at 15 keV after the electrolysis depicted in FIG.5A, including images of oxygen and aluminum contained within the deposits. This series of images demonstrates aluminum oxide deposits. DETAILED DESCRIPTION

[0041] The Hall-Heroult process is a standard industrial procedure for the production of aluminum. The process is typically run at temperatures of above 950 °C and uses highly corrosive liquid cryolite (Na3AlF6) as the electrolyte, due to cryolite’s ability to dissolve alumina (Al2O3) well below its melting point of around 2000 °C.

[0042] Because the process is run at such high temperatures, it is not tolerant to an intermittent power supply. In fact, power loss can result in freezing of the cryolite electrolyte, requiring relining the pot (electrolytic cell) at a cost of around $100-200 thousand. With a potline typically containing around 100 pots in a standard aluminum smelting facility, a power failure can result in a $10 million repair.

[0043] As renewable energy sources, particularly solar and wind energy, continue to drive down the wholesale price of electricity, even into negative spot pricing for hours at a time in areas such as California and Australia, the inability of these energy sources to power aluminum smelting due to reliability issues becomes a lost opportunity for reducing the environmental impact of aluminum smelting. Furthermore, electricity is the second largest cost driver for aluminum production after alumina cost, and aluminum smelting facilities therefore tend to be located in regions with low electricity costs (China, the Middle East, Russia, Canada, Brazil, etc.), with energy generation in these regions typically powered by coal, oil, or hydroelectric sources.

[0044] The ability to integrate ultra-low cost renewable power into aluminum smelting would open up new opportunities for lower cost aluminum with much lower embedded carbon emissions. The emissions used to produce the electricity for aluminum smelting contribute to 70% of the embedded emissions in primary aluminum globally.

[0045] Additionally, the ability to use intermittent renewable energy as an electricity source for aluminum smelting would unlock the utilization of aluminum as an optimal energy 8 IPTS / 200004774.1Attorney Docket No: FEG-019WO storage vector for said renewable energy, which could be easily transported, stockpiled, and discharged to provide energy to various processes.

[0046] To enable aluminum smelting that is tolerant to variable power supply, the temperature of the process must be lowered considerably so that interruptions in power do not compromise the integrity of the cell, either because the temperature is low enough that insulation, waste heat, or other low energy inputs can be used to maintain the temperature, or because there are no deleterious effects from decreasing temperature, or both.

[0047] There are several aspects that may open-up new phase space that were previously disqualifying. One is that for “fuel grade” aluminum, as described herein, the purity requirements are significantly relaxed. LME grade aluminum has a minimum purity of 99.7% (https: / / www.lme.com / - / media / Files / Company / Market-regulation / Rulebook / Rulebook- revisions / Release-122.pdf), however “fuel grade” aluminum (defined herein) can be much lower purity, as low as 50% Al by mass. As such, contaminants that may have previously disqualified certain electrolytes, electrodes, and additives, may be perfectly suitable for producing “fuel grade” Al.

[0048] Provided herein are electrochemical methods for performing aluminum smelting at low temperatures that enable the use of intermittent energy supplies, including intermittent renewable energy supplies. The methods described herein generally utilize a low-melting electrolyte and a non-alumina feedstock for smelting, which mitigates the need for constant energy supply. In certain embodiments of the methods described herein, the feedstock is highly concentrated Al(OH)3 or AlOOH that is produced from the oxidation reactions described in reactions 1 and 2 (see Background section), or the feedstock is another highly concentrated non-alumina feedstock (e.g., Al2S3, AlCl3, AlI3, Al2(SO4)3, KAl(SO4)2 etc.) prepared using the Al(OH)3 and / or AlOOH as a starting material. In addition to the improved sustainability of aluminum smelting that may be achieved by use of intermittent renewable energy sources, use of pure feedstocks avoids the need to extract aluminum oxides from bauxite ore, an environmentally-unfriendly process. The methods described herein may also utilize a non-carbon, inert anode that does not emit CO2 as an oxidation product, thereby further reducing total carbon emissions of the smelting process. Definitions

[0049] Terms used in the claims and specification are defined as set forth below unless otherwise specified. 9 IPTS / 200004774.1Attorney Docket No: FEG-019WO

[0050] It must be noted that, as used in the specification, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.

[0051] The phrase “and / or,” as used in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements).

[0052] As used in the specification and in the claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used shall only be interpreted as indicating exclusive alternatives (i.e., “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.”

[0053] The term “about,” as used herein, means approximately, in the region of, roughly, or around. Unless otherwise stated for a numerical value noted, when the term “about” is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. Unless otherwise stated for a numerical value noted, the term “about” is used herein to modify a numerical value above and below the stated value by a variance of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, or 50%. For nonlimiting example, a range of “about 2 to about 20” can mean 1.98 to 22, or 1 to 30, or other ranges therebetween. Unless otherwise stated for a percentage range noted, when the term “about” is used in conjunction with a percentage range, it modifies that range by extending the boundaries above and below the percentages 10 IPTS / 200004774.1Attorney Docket No: FEG-019WO set forth. Unless otherwise stated for the percentage noted, the term “about” is used herein to modify a percentage above and below the stated percentage by 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, or 50% (as an absolute, which may be limited to 0% as a minimum), or by a percentage of the stated percentage i.e.1% 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, or 50% of the percentage. For nonlimiting example, a range of “about 2% to about 20%” can mean 1% to 21%, or 0% to 70%, or other ranges therebetween, or 1.98% to 22%, or 1% to 30% (as a percentage of the percentage range). For nonlimiting example, a percentage value of “about 30%” can mean 29% to 31%, or 0% to 80%, or other ranges therebetween, or 27% to 33%, or 15% to 45% (as a percentage of the percentage value), or other ranges therebetween. Unless otherwise stated for a numerical range noted, numerical ranges recited herein by endpoints include all numbers and fractions subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.90, 4, and 5). It is also to be understood that all numbers and fractions thereof are presumed to be modified by the term “about.”

[0054] As used herein, the phrase “aluminum-water reaction” refers to the oxidation reaction represented by either / both of the below chemical reactions: Al + 2 H2O → 1.5 H2 + AlO(OH) + Qreaction (Reaction 1) Al + 3 H2O → 1.5 H2 + Al(OH)3 + Qreaction (Reaction 2) wherein Qreaction represents the heat released as a product of the reaction. Whether the reaction of Reaction 1 or the reaction of Reaction 2 occurs depends on the environmental conditions of the reaction, such as pressure, temperature, and pH.

[0055] As used herein, the term “low-melting electrolyte” refers to an electrolyte (e.g., an ionically conducting and electronically insulating compound, electrolyte compound, or mixture described herein), that has a melting point below about 350 °C. In some embodiments, a low-melting electrolyte has a melting point below about 300 °C. In some embodiments, a low-melting electrolyte has a melting point below about 200 °C. In some embodiments, a low-melting electrolyte has a melting point below about 100 °C.

[0056] As used herein, the term “oxidized aluminum feedstock” refers to a compound or mixture of compounds containing oxidized aluminum atoms that is a suitable source of oxidized aluminum for an electrochemical aluminum reduction reaction (e.g., a feedstock described herein). In some embodiments, an oxidized aluminum feedstock contains 11 IPTS / 200004774.1Attorney Docket No: FEG-019WO aluminum atoms in their 3+ oxidation state. In some embodiments, the oxidized aluminum feedstock is one or more of Al(OH)3, AlOOH, Al2S3, Al2(SO4)3, KAl(SO4)2, AlCl3, or AlI3.

[0057] As used herein, the term “fuel grade” refers to a purity grade of aluminum that does not meet the London Metal Exchange (LME) purity requirement of 99.7%, but is still majority aluminum metal (>50% by mass). Low Temperature Aluminum Smelting Methods

[0058] The present disclosure provides methods for aluminum smelting that can be achieved at low temperatures and may utilize intermittent energy sources.

[0059] In one aspect, provided herein is a low temperature electrochemical method for producing aluminum metal, the method comprising: heating a low-melting electrolyte at or above its melting point in an electrolytic cell, thereby providing molten electrolyte in the electrolytic cell, wherein the electrolytic cell comprises an interior volume and one or more anodes and one or more cathodes, wherein the one or more anodes and one or more cathodes are each disposed within the interior volume, and wherein the molten electrolyte is disposed within the interior volume and is in contact with the one or more anodes and one or more cathodes; dissolving an oxidized aluminum feedstock in the molten electrolyte, thereby forming a molten mixture, wherein the molten mixture is in contact with the one or more cathodes and one or more anodes; reducing oxidized aluminum from the oxidized aluminum feedstock to produce aluminum metal at the one or more cathodes of the electrolytic cell by applying a voltage between the one or more cathodes and one or more anodes, wherein the temperature of the molten mixture is maintained at or above its melting point and equal to or below about 350 °C during the reduction, wherein an electrical current through the molten mixture is produced, wherein the electrical current causes the oxidized aluminum to be reduced at the one or more cathodes to form aluminum metal; and removing the aluminum metal from the electrolytic cell, thereby producing aluminum metal, wherein the melting point of the electrolyte is less than or equal to about 350 °C. 12 IPTS / 200004774.1Attorney Docket No: FEG-019WO

[0060] In another aspect, provided herein is a low temperature electrochemical method for producing aluminum metal, the method comprising: heating a low-melting electrolyte at or above its melting point in an electrolytic cell, thereby providing molten electrolyte in the electrolytic cell, wherein the electrolytic cell comprises an interior volume and one or more anodes and one or more cathodes, wherein the one or more anodes and one or more cathodes are each disposed within the interior volume, and wherein the molten electrolyte is disposed within the interior volume and is in contact with the one or more anodes and one or more cathodes; adding an oxidized aluminum feedstock to the molten electrolyte, wherein the oxidized aluminum feedstock does not dissolve, and wherein the oxidized aluminum feedstock is in contact with the one or more cathodes; reducing oxidized aluminum from the oxidized aluminum feedstock to produce aluminum metal at the one or more cathodes of the electrolytic cell by applying a voltage between the one or more cathodes and one or more anodes, wherein the temperature of the molten electrolyte is maintained at or above its melting point and equal to or below about 350 °C during the reduction, wherein an electrical current through the molten electrolyte is produced, wherein the electrical current causes the oxidized aluminum to be reduced at the one or more cathodes to form aluminum metal; and removing the aluminum metal from the electrolytic cell, thereby producing aluminum metal, wherein the melting point of the electrolyte is less than or equal to about 350 °C.

[0061] In some embodiments, the melting point of the electrolyte is less than or equal to about 300 °C. In some embodiments, the melting point of the electrolyte is less than or equal to about 250 °C. In some embodiments, the melting point of the electrolyte is less than or equal to about 200 °C. In some embodiments, the melting point of the electrolyte is less than or equal to about 150 °C. In some embodiments, the melting point of the electrolyte is less than or equal to about 100 °C.

[0062] In some embodiments, the electrolytic cell further comprises thermal insulation. In some embodiments, the electrolytic cell further comprises a heating jacket (e.g., utilizing coolant, steam, electrical heating elements, or other methods) to maintain temperatures in the interior volume of the electrolytic cell. 13 IPTS / 200004774.1Attorney Docket No: FEG-019WO

[0063] In some embodiments, the electrolytic cell further comprises an external heating element and / or an internal heating element. In some embodiments, the electrolytic cell is heated with waste heat from another process.

[0064] In some embodiments, the electrolytic cell comprises housing that is resistant to corrosion, e.g., from molten hydroxides. In some embodiments, the housing comprises PTFE, nickel, and / or PEEK.

[0065] In some embodiments, the method further comprises adding additional oxidized aluminum feedstock to the interior volume of the electrolytic cell to maintain feedstock concentration as oxidized aluminum is consumed.

[0066] In some embodiments, the additional oxidized aluminum feedstock is added in batches. In some embodiments, additional oxidized aluminum feedstock is added every 5 minutes, 10 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 10 hours, or 24 hours. In some embodiments, the additional oxidized aluminum feedstock is added continuously. In some embodiments, the electrolytic cell is hermetically sealed during addition of the additional oxidized aluminum feedstock. In some embodiments, the additional oxidized aluminum feedstock is added using a load lock device to prevent exposure of the electrolytic cell to atmosphere. Load lock devices useful for adding oxidized aluminum feedstock are described in International Publication No. WO 2024 / 243018, the contents of which are incorporated herein by reference.

[0067] In some embodiments, the electrolytic cell is connected to an intermittent energy supply that is used to supply the current and voltage to the electrolytic cell, heat the electrolytic cell, and / or maintain the temperature of the electrolytic cell. In some embodiments, the intermittent energy supply is a renewable energy source selected from electricity generated by solar panels (including a solar array, solar farm, utility installation, commercial installation) and electricity generated by wind turbines. In some embodiments, the renewable energy source is electricity generated by solar panels. In some embodiments, the renewable energy source is electricity generated by wind turbines.

[0068] In some embodiments the power is supplied by a renewable energy source installed behind the meter (off grid). In some embodiments, solar panels are used without inverters that would convert the DC electricity to AC. In some embodiments, the solar array is wired to supply the desired DC voltage to the electrolytic cell or an array of electrolytic cells in series. In some embodiments, wind turbines are used. In some embodiments, the electricity 14 IPTS / 200004774.1Attorney Docket No: FEG-019WO produced by the wind turbines is converted to DC at appropriate currents and voltages to supply the electrolytic cell or an array of electrolytic cells wired in series.

[0069] In some embodiments, a combination of solar panels and wind turbines are used to supply power. In some embodiments, a combination of solar panels, wind turbines, and other renewable energy sources are used to supply power. In some embodiments, the other renewable energy sources’ power outputs are also variable or intermittent. In some embodiments, the other renewable energy sources are firm (outputs that are controllable and not intermittent). In some embodiments, the other renewable energy sources are selected from the group consisting of hydroelectric, geothermal, wave, and nuclear power.

[0070] In some embodiments, the electrolytic cell is connected to an electrical grid that is at least partially powered by renewable energy sources. In some embodiments, electricity supplied to the electrolytic cell is regulated in response to a price signal, for example, if the wholesale spot price of electricity falls below a threshold value or becomes negative, indicating curtailment of variable renewable energy sources on the grid. In some embodiments, the power supplied to the electrolytic cell may be proportional to the level below the price threshold.

[0071] In some embodiments, the electrolytic cell is further connected to a second energy supply selected from the group consisting of an electrochemical battery, a heat battery, waste heat from another process, or a combination thereof, wherein the second energy supply sustains the electrolyte in a molten state when the intermittent energy supply is providing low or no power input.

[0072] In some embodiments, an electrochemical battery (e.g. Li-ion) is used to smooth fluctuations in power from the renewable energy source over short time domains (2 hours, 4 hours, 8 hours, < 12 hours, < 24 hours). In some embodiments, a heat battery is used to smooth fluctuations in power from the renewable energy source, or cell temperatures, over short time domains (2 hours, 4 hours, 8 hours, < 12 hours, < 24 hours). In some embodiments, waste heat from another process is used to smooth fluctuations in power from the renewable energy source, or cell temperatures, over short time domains (2 hours, 4 hours, 8 hours, <12 hours, or <24 hours).

[0073] In some embodiments, the oxidized aluminum feedstock is Al(OH)3, AlOOH, or a mixture of Al(OH)3 and AlOOH. In certain embodiments, the oxidized aluminum feedstock is Al(OH)3. 15 IPTS / 200004774.1Attorney Docket No: FEG-019WO

[0074] In some embodiments, the oxidized aluminum feedstock is Al2S3. In some embodiments, the Al2S3has been produced from a reaction of Al(OH)3and / or AlOOH with sulfur and / or H2S, wherein the Al(OH)3 and / or AlOOH are byproducts of an aluminum-water reaction.

[0075] In some embodiments, the oxidized aluminum feedstock is AlCl3, AlI3, or a mixture of AlCl3and AlI3. In certain embodiments, the oxidized aluminum feedstock is AlCl3. In certain embodiments, the AlCl3 has been produced from a reaction of Al(OH)3 and / or AlOOH with chlorine and / or HCl, wherein the Al(OH)3 and / or AlOOH are byproducts of an aluminum-water reaction. In certain embodiments, the oxidized aluminum feedstock is AlI3. In certain embodiments, the AlI3 has been produced from a reaction of Al(OH)3 and / or AlOOH with iodine and / or HI, wherein the Al(OH)3and / or AlOOH are byproducts of an aluminum-water reaction.

[0076] In some embodiments, the oxidized aluminum feedstock is Al2(SO4)3, KAl(SO4)2, NaAl(SO4)2, or a mixture of Al2(SO4)3 and KAl(SO4)2. In some embodiments, the Al2(SO4)3 has been produced from a reaction of Al(OH)3and / or AlOOH with SO3, either directly or with H2SO4 as an intermediate, wherein the KAl(SO4)2 has been produced from a reaction of the Al2(SO4)3 with K2SO4, wherein the NaAl(SO4)2 has been produced from a reaction of the Al2(SO4)3 with Na2SO4, and wherein the Al(OH)3 and / or AlOOH are byproducts of an aluminum-water reaction.

[0077] In some embodiments, the oxidized aluminum feedstock is at least 90% pure. In some embodiments, the oxidized aluminum feedstock is at least 95% pure. In some embodiments, the oxidized aluminum feedstock is at least 97% pure. In some embodiments, the oxidized aluminum feedstock is at least 99% pure. In some embodiments, the oxidized aluminum feedstock is at least 99.9% pure.

[0078] In some embodiments, the low-melting electrolyte is a low temperature molten salt (LTMS) electrolyte based on a binary, ternary, quaternary, or other mixture of chloride and / or other halide (F, Cl, Br, I) salts. In some embodiments, the LTMS is a binary mixture of chloride and / or other halide (F, Cl, Br, I) salts. In some embodiments, the LTMS is a ternary mixture of chloride and / or other halide (F, Cl, Br, I) salts.

[0079] In some embodiments, the LTMS is about 35 to about 45 mole percent AlCl3and about 55 to about 65 mole percent NaCl. In some embodiments, the LTMS is about 55 to about 65 mole percent AlCl3and about 35 to about 45 mole percent NaCl. In some embodiments, the LTMS is about 55 to about 65 mole percent AlF3 and about 35 to about 45 16 IPTS / 200004774.1Attorney Docket No: FEG-019WO mole percent NaCl. In some embodiments, the LTMS is about 55 to about 65 mole percent AlBr3and about 35 to about 45 mole percent NaCl. In some embodiments, the LTMS is about 55 to about 65 mole percent AlI3 and about 35 to about 45 mole percent NaCl.

[0080] In certain embodiments, the LTMS is 41 mole percent AlCl3and 59 mole percent NaCl (Tm~150 °C). In certain embodiments, the LTMS is 61 mole percent AlCl3 and 39 mole percent NaCl (Tm=102 °C). In certain embodiments, the LTMS is 61 mole percent AlF3and 39 mole percent NaCl. In certain embodiments, the LTMS is 61 mole percent AlI3 and 39 mole percent NaCl. In certain embodiments, the LTMS is 61 mole percent AlBr3 and 39 mole percent NaCl. In certain embodiments, the LTMS is about 54.6 mole percent AlCl3, about 19.1 mole percent LiCl, about 19.5 mole percent NaCl, and about 6.8 mole percent KCl (Tm=85 °C). In certain embodiments, the LTMS is about 54.6 mole percent AlF3, about 19.1 mole percent LiCl, about 19.5 mole percent NaCl , and about 6.8 mole percent KCl. In certain embodiments, the LTMS is about 54.6 mole percent AlI3, about 19.1 mole percent LiCl, about 19.5 mole percent NaCl, and about 6.8 mole percent KCl. In certain embodiments, the LTMS is about 54.6 mole percent AlBr3, about 19.1 mole percent LiCl, about 19.5 mole percent NaCl, and about 6.8 mole percent KCl. In some embodiments, the LTMS is about 61 mole percent AlCl3, about 26 mole percent NaCl, and about 13 mole percent KCl.

[0081] In some embodiments, the low-melting electrolyte is a sulfate based electrolyte. In certain embodiments, the sulfate based electrolyte is KAl(SO4)2(Tm=92-95 °C). In certain embodiments, the sulfate based electrolyte is Al2(SO4)3 (Tm= 86.5 °C (octadecahydrate)). In certain embodiments, the sulfate based electrolyte is a binary, ternary, quaternary, or other mixture of sulfate salts, wherein at least one sulfate salt contains aluminum as a working ion.

[0082] In some embodiments, the low-melting electrolyte is a low temperature molten salt (LTMS) electrolyte based on a binary, ternary, quaternary, or other mixture of metal hydroxide compounds. In some embodiments, the LTMS is a binary mixture of NaOH and KOH. In some embodiments, the LTMS is about 40 to about 60 mole percent NaOH and about 40 to about 60 mole percent KOH. In some embodiments, the LTMS is about 51.5 mole percent NaOH and about 48.5 mole percent KOH. In some embodiments, the LTMS is a binary mixture of CsOH and NaOH. In some embodiments, the LTMS is about 48 mole percent CsOH and about 52 mole percent NaOH (Tm=155 °C). In some embodiments, the LTMS comprises one or more multivalent metal hydroxides (e.g., Mg(OH)2, Ca(OH)2, etc.). 17 IPTS / 200004774.1Attorney Docket No: FEG-019WO In some embodiments, the LTMS comprises metal cations, and the metal cations have reduction potentials lower than Al3+.

[0083] In some embodiments, the electrolytic cell is hermetically sealed, thereby preventing evaporation of aluminum-containing salts (e.g., AlCl3). AlCl3is known to have a particularly high vapor pressure compared to other aluminum-containing salts.

[0084] In some embodiments, the temperature of the molten electrolyte is maintained at about 80 °C after initial heating. In some embodiments, the temperature of the molten electrolyte is maintained at about 100 °C after initial heating. In some embodiments, the temperature of the molten electrolyte is maintained at about 150 °C after initial heating. In some embodiments, the temperature of the molten electrolyte is maintained at about 200 °C after initial heating. In some embodiments, the temperature of the molten electrolyte is maintained at about 250 °C after initial heating. In some embodiments, the temperature of the molten electrolyte is maintained at about 300 °C after initial heating. In some embodiments, the temperature of the molten electrolyte is maintained at about 350 °C after initial heating. In some embodiments, the temperature of the molten electrolyte is maintained well above its melting temperature to optimize reaction kinetics at the cathode and / or anode.

[0085] The one or more anodes may be made of any material that is conductive and stable in the electrolyte at the relevant oxidizing potentials. The one or more anodes may also contain an electrocatalyst to aid in the desired anode reaction (e.g. an oxygen evolution catalyst, chlorine evolution catalyst, sulfur deposition catalyst, etc.). In some embodiments, the one or more anodes are selected from the group consisting of steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures of these metals or their oxides, sulfides, phosphides, or nitrides. In some embodiments, the one or more anodes are non-carbon anodes that do not emit CO2 as an oxidation product.

[0086] In some embodiments, the temperature of the molten electrolyte is raised (e.g., by about 50, 60, 70, 80, 90, or 100 °C) after a period of time of maintenance at the temperature of initial heating.

[0087] The one or more cathodes may be made of any material that is conductive and stable in the electrolyte at the relevant reducing potentials. In some embodiments, the one or more cathodes are selected from the group consisting of aluminum, carbon, graphite, indium, lead, tin, steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures thereof. In some embodiments, 18 IPTS / 200004774.1Attorney Docket No: FEG-019WO the one or more cathodes are aluminum. In some embodiments, the one or more cathodes are patterned or masked to direct the deposition of aluminum into particular geometries (e.g., aluminum pellets that are about 20 mm, about 30 mm, about 40 mm, about 50 mm, about 60 mm, or about 70 mm in diameter). In some embodiments, the pellets are suitable as starting material for an oxidative aluminum-water reaction.

[0088] Upon supplying the current and sufficient voltage, faradaic reactions proceed at the electrodes resulting in the reduction and deposition of metallic aluminum on the one or more cathodes and one of several potential oxidation reactions at the one or more anodes.

[0089] In some embodiments, the cathode half-reaction is one or more of the following: ● Al3++ 3e- → Al0● Al(OH)4- + 3e- → Al0+ 4OH-

[0090] In some embodiments, the anode half-reaction is one or more of the following: ● 4OH- → O2+ 2H2O + 4e- ● 2H2O → O2 + 4H++ 4e- ● H2 → 2H++ 2e- ● H2+ 2OH- → 2H2O + 2e- ● S2-→ S0+ 2 e- ● 2Cl- → Cl2 + 2e- ● 2I- → I2 + 2e- ● 2SO42-→ 2SO3 + O2 + 4e-

[0091] In some embodiments wherein a product of the anode half-reaction is gaseous water, the method further comprises removing the water from the electrolytic cell. In some embodiments, removing the water prevents parasitic water reduction on the cathode.

[0092] In some embodiments, the voltage applied between the one or more cathodes and the one or more anodes is about 1.0, 1.5, 2.0, 2.5, 2.7, 3, 3.5, 4, 4.5, 5, 5.5, or 6 V.

[0093] In some embodiments, the mass ratio of low-melting electrolyte to oxidized aluminum feedstock compound in the electrolytic cell is about 999:1, 99:1, 95:5, 90:10, 80:20, 75:25, 67:33, or 50:50.

[0094] In some embodiments, removing the aluminum metal from the electrolytic cell comprises periodically removing the one or more cathodes after reducing oxidized aluminum for a specified period of time, wherein solid aluminum is deposited on the surface of the one or more cathodes. In some embodiments, the one or more cathodes are removed every 1 hour, 19 IPTS / 200004774.1Attorney Docket No: FEG-019WO 12 hours, 1 day, or 1 week, or as needed depending on the rate of aluminum production. In some embodiments, removing the aluminum comprises heating the electrolytic cell above the melting temperature of aluminum (660 °C), thereby allowing liquid aluminum to flow to the bottom of the electrolytic cell, and removing the liquid aluminum via an outlet at the bottom of the electrolytic cell, or with the assistance of a vacuum, or a combination of both. In some embodiments, the electrolytic cell is operated below the aluminum melting point and then brought to a temperature above the melting point of aluminum and the liquid aluminum is collected according to one of the methods described, and the cell is then brought to a lower temperature for continued operation.

[0095] In some embodiments, removing the aluminum metal from the electrolytic cell comprises periodically removing the one or more cathodes after reducing oxidized aluminum after a specified amount of charge or deposited aluminum mass, wherein solid aluminum is deposited on the surface of the one or more cathodes. In some embodiments, removing the aluminum comprises heating the electrolytic cell above the melting temperature of aluminum (660 °C), thereby allowing liquid aluminum to flow to the bottom of the electrolytic cell, and removing the liquid aluminum via an outlet at the bottom of the electrolytic cell. In some embodiments, the electrolytic cell is operated below the melting temperature of aluminum and then brought to a temperature above the melting temperature of aluminum, and the liquid aluminum is collected according to one of the methods described, and the cell is then brought to a lower temperature for continued operation. EXAMPLES EXAMPLE 1: Preparation of halide based electrolyte (sample A)

[0096] AlCl3 (30.5g) and NaCl (19.5g) (41 mole% AlCl3 and 59 mole% NaCl) were added to a stainless steel dish and mixed with a spatula to form a mixture (FIG.1A). The mixture was then heated with a butane torch until it melted at a temperature of about 150 °C (FIG. 1B). While heating, the mixture was stirred occasionally with a stainless steel spatula.

[0097] The mixture was then cooled, resulting in solidification of the mixture (FIG.1C). EXAMPLE 2: Dissolution of alumina trihydrate (Al(OH)3) in halide based electrolyte

[0098] Sample A prepared in Example 1 was reheated on a hotplate to re-melt the AlCl3 / NaCl mixture.

[0099] A crust repeatedly formed on the top of the liquid due to cooling at the surface. The dish was wrapped in aluminum foil to slow cooling. 20 IPTS / 200004774.1Attorney Docket No: FEG-019WO

[0100] 250 mg of dried Al(OH)3(byproduct of an aluminum-water reaction) was added to the AlCl3 / NaCl mixture (FIG.2A), and the mixture was stirred at about 200 °C. Dissolution behavior of the Al(OH)3 in the AlCl3 / NaCl mixture was observed. Substantial dissolution / dispersion of AlCl3was observed in the mixture after 70 seconds of stirring (FIG. 2B). EXAMPLE 3: Low-temperature aluminum smelting using Al(OH)3 / AlOOH feedstock in a binary / ternary / quaternary halide salt mixture comprising an aluminum halide

[0101] This example describes an aluminum smelting process using Al(OH)3 and / or AlOOH as a feedstock and a binary / ternary / quaternary halide salt mixture comprising an aluminum halide (e.g., AlF3, AlCl3, AlBr3, and / or AlI3) as an electrolyte. The smelting reaction is performed in an electrolytic cell constructed from a material that does not react with the feedstock or electrolyte and can withstand temperatures up to about 700 °C. The electrolytic cell comprises an interior volume in which the feedstock and electrolyte are added / heated, as well as at least one cathode and at least one anode disposed within the electrolytic cell such that they are in contact with the feedstock / electrolyte. The electrolytic cell is thermally insulated to minimize heat loss and is optionally hermetically sealed to the prevent the escape of volatile compounds (e.g., AlCl3).

[0102] The halide salt mixture electrolyte is added to the interior volume of the electrolytic cell and heated to a temperature at or above its melting temperature, which can range from, e.g., about 80 °C to about 150 °C, depending on the composition of the electrolyte mixture. The melting temperature of a specific electrolyte mixture may be readily determined by, for example, heating the solid mixture until it melts / liquifies and monitoring the temperature at the point of melting.

[0103] Once the electrolyte is melted, Al(OH)3 and / or AlOOH feedstock are dissolved / dispersed within the molten electrolyte. The Al(OH)3and / or AlOOH may be byproducts of an aluminum-water oxidation reaction, and may have a high degree of purity (e.g., >95%). The amount of Al(OH)3 / AlOOH added relative to the molten electrolyte may vary, and may range from about 0.1% to about 50% by weight.

[0104] The cathode and / or anode may be installed prior to or after addition of the electrolyte and / or feedstock to the electrolytic cell. If the cathode and / or anode are not installed prior to addition of the electrolyte and feedstock, they may be installed after dissolution / dispersion of the feedstock in the electrolyte. The cathode may be any suitable cathode for reducing Al3+to Al0(e.g., aluminum, carbon, graphite, indium, lead, tin, steel, 21 IPTS / 200004774.1Attorney Docket No: FEG-019WO stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures thereof) according to the following reaction: Al3++ 3e- → Al0

[0105] The anode may be any suitable anode for performing the desired oxidation reaction (e.g., steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures of these metals or their oxides, sulfides, phosphides, or nitrides). In particular, the anode may be an inert, non-carbon anode that does not generate CO2 as an oxidation product. Oxidation at the anode may occur according to the following reaction: 4OH- → O2(g)↑ + 2H2O(g)↑ + 4e-

[0106] Once the feedstock is dissolved / dispersed in the electrolyte, and the cathode / anode are installed, a voltage is applied between the cathode and the anode, resulting in a DC current flowing through the feedstock / electrolyte mixture and reduction of Al3+to aluminum at the cathode (e.g., resulting in deposition of aluminum on the cathode surface). The voltage applied may range from about 1.5 V to about 6 V. The electrochemical reduction is performed at or above the melting temperature of the electrolyte but generally remains below about 350 °C. The electrochemical reduction may run at 10 A for 8 hours sufficient to produce about 27 g of aluminum.

[0107] Feedstock may also be continuously added to the electrolytic cell to maintain feedstock concentrations as the original feedstock is consumed, resulting in continuous aluminum production. The addition of feedstock is optionally performed using a method that does not expose the electrolytic cell to atmosphere, thereby preventing the escape of volatile compounds.

[0108] Aluminum produced in the electrolytic cell is removed, for example, by a) removing the cathode with deposited aluminum when the temperature in the electrolytic cell is below the melting temperature of aluminum; or b) heating the electrolytic cell above the melting temperature of aluminum, thereby melting the aluminum, and removing the melted aluminum through an outlet at the base of the electrolytic cell. Removal of liquid aluminum through an outlet may be assisted by a vacuum. An exemplary process is depicted in FIG. 3A.

[0109] The relatively low reaction temperature allows the reaction to be powered, at least in part, by an intermittent energy source (for example, an intermittent source of renewable energy such as solar panel-generated electricity or wind turbine-generated electricity) because 22 IPTS / 200004774.1Attorney Docket No: FEG-019WO required temperatures can be maintained in the electrolytic cell without constant power supply. The electrolytic cell is optionally heated primarily with an intermittent energy source. Optionally, a secondary energy source (e.g., a battery) may be used to heat the electrolytic cell when energy supply from the primary intermittent source is low. The energy for heating the electrolytic cell may also be provided from the electrical grid. In an example of this scenario, the power to the cell is regulated in response to a price signal, for example, if the wholesale spot price of electricity falls below a threshold value or becomes negative, indicating forthcoming curtailment of variable renewable energy sources on the grid. Further, the power applied to the cell may be proportional to the level below the price threshold (lower price = more power). EXAMPLE 4: Low-temperature aluminum smelting using Al2S3 feedstock in a binary / ternary / quaternary halide salt mixture comprising an aluminum halide

[0110] This example describes an aluminum smelting process using Al2S3 as a feedstock and a binary / ternary / quaternary halide salt mixture comprising an aluminum halide (e.g., AlF3, AlCl3, AlBr3, and / or AlI3) as an electrolyte. The smelting reaction is performed in an electrolytic cell constructed from a material that does not react with the feedstock or electrolyte and can withstand temperatures up to about 700 °C. The electrolytic cell comprises an interior volume in which the feedstock and electrolyte are added / heated, as well as at least one cathode and at least one anode disposed within the electrolytic cell such that they are in contact with the feedstock / electrolyte. The electrolytic cell is thermally insulated to minimize heat loss and is optionally hermetically sealed to the prevent the escape of volatile compounds (e.g., AlCl3).

[0111] The halide salt mixture electrolyte is added to the interior volume of the electrolytic cell and heated to a temperature at or above its melting temperature, which can range from, e.g., about 80 °C to about 150 °C, depending on the composition of the electrolyte mixture. The melting temperature of a specific electrolyte mixture may be readily determined by, for example, heating the solid mixture until it melts / liquifies and monitoring the temperature at the point of melting.

[0112] Once the electrolyte is melted, Al2S3 feedstock is dissolved / dispersed within the molten electrolyte. The Al2S3may be formed from the reaction Al(OH)3and / or AlOOH of sulfur and / or H2S. The Al(OH)3 and / or AlOOH may be byproducts of an aluminum-water oxidation reaction, and may have a high degree of purity (e.g., >95%). The amount of Al2S323 IPTS / 200004774.1Attorney Docket No: FEG-019WO added relative to the molten electrolyte may vary, and may range from about 0.1% to about 50% by weight.

[0113] The cathode and / or anode may be installed prior to or after addition of the electrolyte and / or feedstock to the electrolytic cell. If the cathode and / or anode are not installed prior to addition of the electrolyte and feedstock, they may be installed after dissolution / dispersion of the feedstock in the electrolyte. The cathode may be any suitable cathode for reducing Al3+to Al0(e.g., aluminum, carbon, graphite, indium, lead, tin, steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures thereof) according to the following reaction: Al3++ 3e- → Al0

[0114] The anode may be any suitable anode for performing the desired oxidation reaction (e.g., steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures of these metals or their oxides, sulfides, phosphides, or nitrides). In particular, the anode may be an inert, non-carbon anode that does not generate CO2 as an oxidation product. Oxidation at the anode may occur according to the following reaction: S2-→ S0(l) + 2 e- Sulfur produced at the anode is optionally collected and used to generate additional Al2S3 feedstock from Al(OH)3and / or AlOOH.

[0115] Once the feedstock is dissolved / dispersed in the electrolyte, and the cathode / anode are installed, a voltage is applied between the cathode and the anode, resulting in a DC current flowing through the feedstock / electrolyte mixture and reduction of Al3+to aluminum at the cathode (e.g., resulting in deposition of aluminum on the cathode surface). The voltage applied may range from about 1.5 V to about 6 V. The electrochemical reduction is performed at or above the melting temperature of the electrolyte but generally remains below about 350 °C. The electrochemical reduction may run at 10 A for 8 hours sufficient to produce about 27 g of aluminum.

[0116] Feedstock may also be continuously added to the electrolytic cell to maintain feedstock concentrations as the original feedstock is consumed, resulting in continuous aluminum production. The addition of feedstock is optionally performed using a method that does not expose the electrolytic cell to atmosphere, thereby preventing the escape of volatile compounds. 24 IPTS / 200004774.1Attorney Docket No: FEG-019WO

[0117] Aluminum produced in the electrolytic cell is removed, for example, by a) removing the cathode with deposited aluminum when the temperature in the electrolytic cell is below the melting temperature of aluminum; or b) heating the electrolytic cell above the melting temperature of aluminum, thereby melting the aluminum, and removing the melted aluminum through an outlet at the base of the electrolytic cell Removal of liquid aluminum through an outlet may be assisted by a vacuum. An exemplary process is depicted in FIG. 3B.

[0118] The relatively low reaction temperature allows the reaction to be powered, at least in part, by an intermittent energy source (for example, an intermittent source of renewable energy such as solar panel-generated electricity or wind turbine-generated electricity) because required temperatures can be maintained in the electrolytic cell without constant power supply. The electrolytic cell is optionally heated primarily with an intermittent energy source. Optionally, a secondary energy source (e.g., a battery) may be used to heat the electrolytic cell when energy supply from the primary intermittent source is low. The energy for heating the electrolytic cell may also be provided from the electrical grid. In an example of this scenario, the power to the cell is regulated in response to a price signal, for example, if the wholesale spot price of electricity falls below a threshold value or becomes negative, indicating forthcoming curtailment of variable renewable energy sources on the grid. Further, the power applied to the cell may be proportional to the level below the price threshold (lower price = more power). EXAMPLE 5: Low-temperature aluminum smelting using AlCl3 or AlI3 feedstock in a binary / ternary / quaternary halide salt mixture comprising an aluminum halide

[0119] This example describes an aluminum smelting process using AlCl3or AlI3as a feedstock and a binary / ternary / quaternary halide salt mixture comprising an aluminum halide (e.g., AlF3, AlCl3, AlBr3, and / or AlI3) as an electrolyte. The smelting reaction is performed in an electrolytic cell constructed from a material that does not react with the feedstock or electrolyte and can withstand temperatures up to about 700 °C. The electrolytic cell comprises an interior volume in which the feedstock and electrolyte are added / heated, as well as at least one cathode and at least one anode disposed within the electrolytic cell such that they are in contact with the feedstock / electrolyte. The electrolytic cell is thermally insulated to minimize heat loss and is optionally hermetically sealed to the prevent the escape of volatile compounds (e.g., AlCl3). 25 IPTS / 200004774.1Attorney Docket No: FEG-019WO

[0120] The halide salt mixture electrolyte is added to the interior volume of the electrolytic cell and heated to a temperature at or above its melting temperature, which can range from, e.g., about 80 °C to about 150 °C, depending on the composition of the electrolyte mixture. The melting temperature of a specific electrolyte mixture may be readily determined by, for example, heating the solid mixture until it melts / liquifies and monitoring the temperature at the point of melting.

[0121] Once the electrolyte is melted, the AlCl3 or AlI3 feedstock is dissolved / dispersed within the molten electrolyte. The AlCl3 may be formed from the reaction Al(OH)3 and / or AlOOH with chlorine gas or HCl. The AlI3 may be formed from the reaction Al(OH)3 and / or AlOOH with iodine or HI. The Al(OH)3 and / or AlOOH may be byproducts of an aluminum- water oxidation reaction, and may have a high degree of purity (e.g., >95%). The amount of AlCl3 or AlI3 added relative to the molten electrolyte may vary, and may range from about 0.1% to about 50% by weight.

[0122] The cathode and / or anode may be installed prior to or after addition of the electrolyte and / or feedstock to the electrolytic cell. If the cathode and / or anode are not installed prior to addition of the electrolyte and feedstock, they may be installed after dissolution / dispersion of the feedstock in the electrolyte. The cathode may be any suitable cathode for reducing Al3+to Al0(e.g., aluminum, carbon, graphite, indium, lead, tin, steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures thereof) according to the following reaction: Al3++ 3e- → Al0

[0123] The anode may be any suitable anode for performing the desired oxidation reaction (e.g., steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures of these metals or their oxides, sulfides, phosphides, or nitrides). In particular, the anode may be an inert, non-carbon anode that does not generate CO2 as an oxidation product. Oxidation at the anode may occur according to one or more of the following reactions (depending on the feedstock): 2Cl- → Cl2(g)↑ + 2e-2I- → I20(l) + 2e- Cl2 and I2 generated at the anode are optionally collected and used to generate additional AlCl3 and AlI3, respectively, from Al(OH)3 and / or AlOOH. 26 IPTS / 200004774.1Attorney Docket No: FEG-019WO

[0124] Once the feedstock is dissolved / dispersed in the electrolyte, and the cathode / anode are installed, a voltage is applied between the cathode and the anode, resulting in a DC current flowing through the feedstock / electrolyte mixture and reduction of Al3+to aluminum at the cathode (e.g., resulting in deposition of aluminum on the cathode surface). The voltage applied may range from about 1.5 V to about 6 V. The electrochemical reduction is performed at or above the melting temperature of the electrolyte but generally remains below about 350 °C. The electrochemical reduction may run at 10 A for 8 hours sufficient to produce about 27 g of aluminum.

[0125] Feedstock may also be continuously added to the electrolytic cell to maintain feedstock concentrations as the original feedstock is consumed, resulting in continuous aluminum production. The addition of feedstock is optionally performed using a method that does not expose the electrolytic cell to atmosphere, thereby preventing the escape of volatile compounds.

[0126] Aluminum produced in the electrolytic cell is removed, for example, by a) removing the cathode with deposited aluminum when the temperature in the electrolytic cell is below the melting temperature of aluminum; or b) heating the electrolytic cell above the melting temperature of aluminum, thereby melting the aluminum, and removing the melted aluminum through an outlet at the base of the electrolytic cell. Removal of liquid aluminum through an outlet may be assisted by a vacuum.

[0127] The relatively low reaction temperature allows the reaction to be powered, at least in part, by an intermittent energy source (for example, an intermittent source of renewable energy such as solar panel-generated electricity or wind turbine-generated electricity) because required temperatures can be maintained in the electrolytic cell without constant power supply. The electrolytic cell is optionally heated primarily with an intermittent energy source. Optionally, a secondary energy source (e.g., a battery) may be used to heat the electrolytic cell when energy supply from the primary intermittent source is low. The energy for heating the electrolytic cell may also be provided from the electrical grid. In an example of this scenario, the power to the cell is regulated in response to a price signal, for example, if the wholesale spot price of electricity falls below a threshold value or becomes negative, indicating forthcoming curtailment of variable renewable energy sources on the grid. Further, the power applied to the cell may be proportional to the level below the price threshold (lower price = more power). 27 IPTS / 200004774.1Attorney Docket No: FEG-019WO EXAMPLE 6: Low-temperature aluminum smelting using Al(OH)3 / AlOOH feedstock in a sulfate-based electrolyte

[0128] This example describes an aluminum smelting process using Al(OH)3 and / or AlOOH as a feedstock and a sulfate compound as an electrolyte (e.g., KAl(SO4)2or Al2(SO4)3). The smelting reaction is performed in an electrolytic cell constructed from a material that does not react with the feedstock or electrolyte and can withstand temperatures up to about 700 °C. The electrolytic cell comprises an interior volume in which the feedstock and electrolyte are added / heated, as well as at least one cathode and at least one anode disposed within the electrolytic cell such that they are in contact with the feedstock / electrolyte. The electrolytic cell is thermally insulated to minimize heat loss and is optionally hermetically sealed to the prevent the escape of volatile compounds.

[0129] The sulfate-based electrolyte is added to the interior volume of the electrolytic cell and heated to a temperature at or above its melting temperature, which can range from, e.g., about 80 °C to about 100 °C, depending on the composition of the electrolyte. The melting temperature of a specific electrolyte may be readily determined by, for example, heating the solid mixture until it melts / liquifies and monitoring the temperature at the point of melting.

[0130] Once the electrolyte is melted, Al(OH)3 and / or AlOOH feedstock are dissolved / dispersed within the molten electrolyte. The Al(OH)3and / or AlOOH may be byproducts of an aluminum-water oxidation reaction, and may have a high degree of purity (e.g., >95%). The amount of Al(OH)3 / AlOOH added relative to the molten electrolyte may vary, and may range from about 0.1% to about 50% by weight.

[0131] The cathode and / or anode may be installed prior to or after addition of the electrolyte and / or feedstock to the electrolytic cell. If the cathode and / or anode are not installed prior to addition of the electrolyte and feedstock, they may be installed after dissolution / dispersion of the feedstock in the electrolyte. The cathode may be any suitable cathode for reducing Al3+to Al0(e.g., aluminum, carbon, graphite, indium, lead, tin, steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures thereof) according to the following reaction: Al3++ 3e- → Al0

[0132] The anode may be any suitable anode for performing the desired oxidation reaction (e.g., steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures of these metals or their oxides, sulfides, phosphides, or nitrides). In particular, the anode may be an inert, non-carbon anode 28 IPTS / 200004774.1Attorney Docket No: FEG-019WO that does not generate CO2as an oxidation product. Oxidation at the anode may occur according to one or more of the following reactions: 4OH- → O2(g)↑ + 2H2O(g)↑ + 4e- 2SO42-→ 2SO3(g)↑ + O2(g)↑ + 4e-

[0133] Once the feedstock is dissolved / dispersed in the electrolyte, and the cathode / anode are installed, a voltage is applied between the cathode and the anode, resulting in a DC current flowing through the feedstock / electrolyte mixture and reduction of Al3+to aluminum at the cathode (e.g., resulting in deposition of aluminum on the cathode surface). The voltage applied may range from 1.5 V to 6 V. The electrochemical reduction is performed at or above the melting temperature of the electrolyte but generally remains below about 350 °C. The electrochemical reduction may run at 10 A for 8 hours sufficient to produce about 27 g of aluminum.

[0134] Feedstock may also be continuously added to the electrolytic cell to maintain feedstock concentrations as the original feedstock is consumed, resulting in continuous aluminum production. The addition of feedstock is optionally performed using a method that does not expose the electrolytic cell to atmosphere, thereby preventing the escape of volatile compounds.

[0135] Aluminum produced in the electrolytic cell is removed, for example, by a) removing the cathode with deposited aluminum when the temperature in the electrolytic cell is below the melting temperature of aluminum; or b) heating the electrolytic cell above the melting temperature of aluminum, thereby melting the aluminum, and removing the melted aluminum through an outlet at the base of the electrolytic cell. Removal of liquid aluminum through an outlet may be assisted by a vacuum. An exemplary process is depicted in FIG. 3A.

[0136] The relatively low reaction temperature allows the reaction to be powered, at least in part, by an intermittent energy source (for example, an intermittent source of renewable energy such as solar panel-generated electricity or wind turbine-generated electricity) because required temperatures can be maintained in the electrolytic cell without constant power supply. The electrolytic cell is optionally heated primarily with an intermittent energy source. Optionally, a secondary energy source (e.g., a battery) may be used to heat the electrolytic cell when energy supply from the primary intermittent source is low. The energy for heating the electrolytic cell may also be provided from the electrical grid. In an example of this scenario, the power to the cell is regulated in response to a price signal, for example, if the 29 IPTS / 200004774.1Attorney Docket No: FEG-019WO wholesale spot price of electricity falls below a threshold value or becomes negative, indicating forthcoming curtailment of variable renewable energy sources on the grid. Further, the power applied to the cell may be proportional to the level below the price threshold (lower price = more power). EXAMPLE 7: Low-temperature aluminum smelting using Al2S3 feedstock in a sulfate- based electrolyte

[0137] This example describes an aluminum smelting process using Al2S3as a feedstock and a sulfate compound as an electrolyte (e.g., KAl(SO4)2 or Al2(SO4)3). The smelting reaction is performed in an electrolytic cell constructed from a material that does not react with the feedstock or electrolyte and can withstand temperatures up to about 700 °C. The electrolytic cell comprises an interior volume in which the feedstock and electrolyte are added / heated, as well as at least one cathode and at least one anode disposed within the electrolytic cell such that they are in contact with the feedstock / electrolyte. The electrolytic cell is thermally insulated to minimize heat loss and is optionally hermetically sealed to the prevent the escape of volatile compounds.

[0138] The sulfate-based electrolyte is added to the interior volume of the electrolytic cell and heated to a temperature at or above its melting temperature, which can range from, e.g., about 80 °C to about 100 °C, depending on the composition of the electrolyte. The melting temperature of a specific electrolyte may be readily determined by, for example, heating the solid mixture until it melts / liquifies and monitoring the temperature at the point of melting.

[0139] Once the electrolyte is melted, Al2S3feedstock is dissolved / dispersed within the molten electrolyte. The Al2S3 may be formed from the reaction Al(OH)3 and / or AlOOH with sulfur and / or H2S. The Al(OH)3and / or AlOOH may be byproducts of an aluminum-water oxidation reaction, and may have a high degree of purity (e.g., >95%). The amount of Al2S3 added relative to the molten electrolyte may vary, and may range from about 0.1% to about 50% by weight.

[0140] The cathode and / or anode may be installed prior to or after addition of the electrolyte and / or feedstock to the electrolytic cell. If the cathode and / or anode are not installed prior to addition of the electrolyte and feedstock, they may be installed after dissolution / dispersion of the feedstock in the electrolyte. The cathode may be any suitable cathode for reducing Al3+to Al0(e.g., aluminum, carbon, graphite, indium, lead, tin, steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures thereof) according to the following reaction: 30 IPTS / 200004774.1Attorney Docket No: FEG-019WO Al3++ 3e- → Al0

[0141] The anode may be any suitable anode for performing the desired oxidation reaction (e.g., steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures of these metals or their oxides, sulfides, phosphides, or nitrides). In particular, the anode may be an inert, non-carbon anode that does not generate CO2as an oxidation product. Oxidation at the anode may occur according to one or more of the following reactions: S2-→ S0(l) + 2 e- 2SO42-→ 2SO3(g)↑ + O2(g)↑ + 4e- Sulfur produced at the anode is optionally collected and used to generate additional Al2S3feedstock from Al(OH)3 and / or AlOOH.

[0142] Once the feedstock is dissolved / dispersed in the electrolyte, and the cathode / anode are installed, a voltage is applied between the cathode and the anode, resulting in a DC current flowing through the feedstock / electrolyte mixture and reduction of Al3+to aluminum at the cathode (e.g., resulting in deposition of aluminum on the cathode surface). The voltage applied may range from about 1.5 V to about 6 V. The electrochemical reduction is performed at or above the melting temperature of the electrolyte but generally remains below about 350 °C. The electrochemical reduction may run at 10 A for 8 hours sufficient to produce about 27 g of aluminum.

[0143] Feedstock may also be continuously added to the electrolytic cell to maintain feedstock concentrations as the original feedstock is consumed, resulting in continuous aluminum production. The addition of feedstock is optionally performed using a method that does not expose the electrolytic cell to atmosphere, thereby preventing the escape of volatile compounds.

[0144] Aluminum produced in the electrolytic cell is removed, for example, by a) removing the cathode with deposited aluminum when the temperature in the electrolytic cell is below the melting temperature of aluminum; or b) heating the electrolytic cell above the melting temperature of aluminum, thereby melting the aluminum, and removing the melted aluminum through an outlet at the base of the electrolytic cell. Removal of liquid aluminum through an outlet may be assisted by a vacuum. An exemplary process is depicted in FIG. 3B. 31 IPTS / 200004774.1Attorney Docket No: FEG-019WO

[0145] The relatively low reaction temperature allows the reaction to be powered, at least in part, by an intermittent energy source (for example, an intermittent source of renewable energy such as solar panel-generated electricity or wind turbine-generated electricity) because required temperatures can be maintained in the electrolytic cell without constant power supply. The electrolytic cell is optionally heated primarily with an intermittent energy source. Optionally, a secondary energy source (e.g., a battery) may be used to heat the electrolytic cell when energy supply from the primary intermittent source is low. The energy for heating the electrolytic cell may also be provided from the electrical grid. In an example of this scenario, the power to the cell is regulated in response to a price signal, for example, if the wholesale spot price of electricity falls below a threshold value or becomes negative, indicating forthcoming curtailment of variable renewable energy sources on the grid. Further, the power applied to the cell may be proportional to the level below the price threshold (lower price = more power). EXAMPLE 8: Low-temperature aluminum smelting using AlCl3 or AlI3 feedstock in a sulfate-based electrolyte

[0146] This example describes an aluminum smelting process using AlCl3 or AlI3 as a feedstock and a sulfate compound as an electrolyte (e.g., KAl(SO4)2or Al2(SO4)3). The smelting reaction is performed in an electrolytic cell constructed from a material that does not react with the feedstock or electrolyte and can withstand temperatures up to about 700 °C. The electrolytic cell comprises an interior volume in which the feedstock and electrolyte are added / heated, as well as at least one cathode and at least one anode disposed within the electrolytic cell such that they are in contact with the feedstock / electrolyte. The electrolytic cell is thermally insulated to minimize heat loss and is optionally hermetically sealed to the prevent the escape of volatile compounds.

[0147] The sulfate-based electrolyte is added to the interior volume of the electrolytic cell and heated to a temperature at or above its melting temperature, which can range from, e.g., about 80 °C to about 100 °C, depending on the composition of the electrolyte. The melting temperature of a specific electrolyte may be readily determined by, for example, heating the solid mixture until it melts / liquifies and monitoring the temperature at the point of melting.

[0148] Once the electrolyte is melted, the AlCl3or AlI3feedstock is dissolved / dispersed within the molten electrolyte. The AlCl3 may be formed from the reaction Al(OH)3 and / or 32 IPTS / 200004774.1Attorney Docket No: FEG-019WO AlOOH with chlorine gas or HCl. The AlI3may be formed from the reaction Al(OH)3and / or AlOOH with iodine or HI. The Al(OH)3and / or AlOOH may be byproducts of an aluminum- water oxidation reaction, and may have a high degree of purity (e.g., >95%). The amount of AlCl3or AlI3added relative to the molten electrolyte may vary, and may range from about 0.1% to about 50% by weight.

[0149] The cathode and / or anode may be installed prior to or after addition of the electrolyte and / or feedstock to the electrolytic cell. If the cathode and / or anode are not installed prior to addition of the electrolyte and feedstock, they may be installed after dissolution / dispersion of the feedstock in the electrolyte. The cathode may be any suitable cathode for reducing Al3+to Al0(e.g., aluminum, carbon, graphite, indium, lead, tin, steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures thereof) according to the following reactions (depending on the feedstock): Al3++ 3e- → Al0

[0150] The anode may be any suitable anode for performing the desired oxidation reaction (e.g., steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures of these metals or their oxides, sulfides, phosphides, or nitrides). In particular, the anode may be an inert, non-carbon anode that does not generate CO2 as an oxidation product. Oxidation at the anode may occur according to one or more of the following reactions: 2Cl- → Cl2(g)↑ + 2e- 2I- → I20(l) + 2e- 2SO42-→ 2SO3(g)↑ + O2(g)↑ + 4e- Cl2and I2generated at the anode are optionally collected and used to generate additional AlCl3 and AlI3, respectively, from Al(OH)3 and / or AlOOH.

[0151] Once the feedstock is dissolved / dispersed in the electrolyte, and the cathode / anode are installed, a voltage is applied between the cathode and the anode, resulting in a DC current flowing through the feedstock / electrolyte mixture and reduction of Al3+to aluminum at the cathode (e.g., resulting in deposition of aluminum on the cathode surface). The voltage applied may range from about 1.5 V to about 6 V. The electrochemical reduction is performed at or above the melting temperature of the electrolyte but generally remains below 33 IPTS / 200004774.1Attorney Docket No: FEG-019WO about 350 °C. The electrochemical reduction may run at 10 A for 8 hours sufficient to produce about 27 g of aluminum.

[0152] Feedstock may also be continuously added to the electrolytic cell to maintain feedstock concentrations as the original feedstock is consumed, resulting in continuous aluminum production. The addition of feedstock is optionally performed using a method that does not expose the electrolytic cell to atmosphere, thereby preventing the escape of volatile compounds.

[0153] Aluminum produced in the electrolytic cell is removed, for example, by a) removing the cathode with deposited aluminum when the temperature in the electrolytic cell is below the melting temperature of aluminum; or b) heating the electrolytic cell above the melting temperature of aluminum, thereby melting the aluminum, and removing the melted aluminum through an outlet at the base of the electrolytic cell. Removal of liquid aluminum through an outlet may be assisted by a vacuum.

[0154] The relatively low reaction temperature allows the reaction to be powered, at least in part, by an intermittent energy source (for example, an intermittent source of renewable energy such as solar panel-generated electricity or wind turbine-generated electricity) because required temperatures can be maintained in the electrolytic cell without constant power supply. The electrolytic cell is optionally heated primarily with an intermittent energy source. Optionally, a secondary energy source (e.g., a battery) may be used to heat the electrolytic cell when energy supply from the primary intermittent source is low. The energy for heating the electrolytic cell may also be provided from the electrical grid. In an example of this scenario, the power to the cell is regulated in response to a price signal, for example, if the wholesale spot price of electricity falls below a threshold value or becomes negative, indicating forthcoming curtailment of variable renewable energy sources on the grid. Further, the power applied to the cell may be proportional to the level below the price threshold (lower price = more power). EXAMPLE 9: Low-temperature aluminum smelting using KAl(SO4)2 / Al2(SO4)3 feedstock in a sulfate-based electrolyte

[0155] This example describes an aluminum smelting process using KAl(SO4)2 and / or Al2(SO4)3as a feedstock and a sulfate compound as an electrolyte (e.g., KAl(SO4)2or Al2(SO4)3). The smelting reaction is performed in an electrolytic cell constructed from a material that does not react with the feedstock or electrolyte and can withstand temperatures up to about 700 °C. The electrolytic cell comprises an interior volume in which the feedstock 34 IPTS / 200004774.1Attorney Docket No: FEG-019WO and electrolyte are added / heated, as well as at least one cathode and at least one anode disposed within the electrolytic cell such that they are in contact with the feedstock / electrolyte. The electrolytic cell is thermally insulated to minimize heat loss and is optionally hermetically sealed to the prevent the escape of volatile compounds.

[0156] The sulfate-based electrolyte is added to the interior volume of the electrolytic cell and heated to a temperature at or above its melting temperature, which can range from, e.g., about 80 °C to about 100 °C, depending on the composition of the electrolyte. The melting temperature of a specific electrolyte may be readily determined by, for example, heating the solid mixture until it melts / liquifies and monitoring the temperature at the point of melting.

[0157] Once the electrolyte is melted, the KAl(SO4)2and / or Al2(SO4)3feedstock is dissolved / dispersed within the molten electrolyte. The Al2(SO4)3 may be formed from the reaction Al(OH)3and / or AlOOH with SO3, either directly or with H2SO4as an intermediate. Al2(SO4)3 may be reacted with K2SO4 to produce the KAl(SO4)2. The Al(OH)3 and / or AlOOH may be byproducts of an aluminum-water oxidation reaction, and may have a high degree of purity (e.g., >95%). The amount of KAl(SO4)2 and / or Al2(SO4)3 added relative to the molten electrolyte may vary, and may range from about 0.1% to about 50% by weight.

[0158] The cathode and / or anode may be installed prior to or after addition of the electrolyte and / or feedstock to the electrolytic cell. If the cathode and / or anode are not installed prior to addition of the electrolyte and feedstock, they may be installed after dissolution / dispersion of the feedstock in the electrolyte. The cathode may be any suitable cathode for reducing Al3+to Al0(e.g., aluminum, carbon, graphite, indium, lead, tin, steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures thereof) according to the following reactions (depending on the feedstock): Al3++ 3e- → Al0

[0159] The anode may be any suitable anode for performing the desired oxidation reaction (e.g., steel, stainless steel, titanium, iron, nickel, cobalt, chromium, copper, tungsten, molybdenum, gold, platinum, palladium, iridium, or mixtures of these metals or their oxides, sulfides, phosphides, or nitrides). In particular, the anode may be an inert, non-carbon anode that does not generate CO2 as an oxidation product. Oxidation at the anode may occur according to one or more of the following reactions: 2SO42-→ 2SO3(g)↑ + O2(g)↑ + 4e- 35 IPTS / 200004774.1Attorney Docket No: FEG-019WO SO3generated at the anode is optionally collected and used to generate additional Al2(SO4)3from Al(OH)3and / or AlOOH.

[0160] Once the feedstock is dissolved / dispersed in the electrolyte, and the cathode / anode are installed, a voltage is applied between the cathode and the anode, resulting in a DC current flowing through the feedstock / electrolyte mixture and reduction of Al3+to aluminum at the cathode (e.g., resulting in deposition of aluminum on the cathode surface). The voltage applied may range from about 1.5 V to about 6 V. The electrochemical reduction is performed at or above the melting temperature of the electrolyte but generally remains below about 350 °C. The electrochemical reduction may run at 10 A for 8 hours sufficient to produce about 27 g of aluminum.

[0161] Feedstock may also be continuously added to the electrolytic cell to maintain feedstock concentrations as the original feedstock is consumed, resulting in continuous aluminum production. The addition of feedstock is optionally performed using a method that does not expose the electrolytic cell to atmosphere, thereby preventing the escape of volatile compounds.

[0162] Aluminum produced in the electrolytic cell is removed, for example, by a) removing the cathode with deposited aluminum when the temperature in the electrolytic cell is below the melting temperature of aluminum; or b) heating the electrolytic cell above the melting temperature of aluminum, thereby melting the aluminum, and removing the melted aluminum through an outlet at the base of the electrolytic cell. Removal of liquid aluminum through an outlet may be assisted by a vacuum.

[0163] The relatively low reaction temperature allows the reaction to be powered, at least in part, by an intermittent energy source (for example, an intermittent source of renewable energy such as solar panel-generated electricity or wind turbine-generated electricity) because required temperatures can be maintained in the electrolytic cell without constant power supply. The electrolytic cell is optionally heated primarily with an intermittent energy source. Optionally, a secondary energy source (e.g., a battery) may be used to heat the electrolytic cell when energy supply from the primary intermittent source is low. The energy for heating the electrolytic cell may also be provided from the electrical grid. In an example of this scenario, the power to the cell is regulated in response to a price signal, for example, if the wholesale spot price of electricity falls below a threshold value or becomes negative, indicating forthcoming curtailment of variable renewable energy sources on the grid. Further, 36 IPTS / 200004774.1Attorney Docket No: FEG-019WO the power applied to the cell may be proportional to the level below the price threshold (lower price = more power). EXAMPLE 10: NaOH-KOH eutectic mixture as an electrolyte for reduction of aluminum-water reaction byproduct (alumina trihydrate and / or boehmite) Experiment 1:

[0164] NaOH (20.81 g) and KOH (29.19 g) (1:1 mol ratio) were added to a five-neck flask. The resulting mixture was stirred and heated to 230 °C with a heating mantle to melt the mixture at a temperature below the melting points of NaOH and KOH. After melting, the byproduct (82 mg, 165 mg, or 252 mg) was added to the molten mixture and stirred, resulting in dissolution of the aluminum trihydrate in the electrolyte.

[0165] It is contemplated that the byproduct may be reduced to aluminum by electrolysis within the molten mixture. This may be accomplished using platinum coils as the working electrode and counter electrode, and an aluminum rod as the reference electrode. Application of a voltage of about 3V between the anode and cathode (or <0 as compared to the aluminum reference electrode) is expected to achieve the desired reduction to aluminum. Successful reduction to aluminum may require removal of dissolved water from the molten mixture, e.g., by application of heat or electrolysis, prior to reduction. Experiment 2:

[0166] NaOH (20.90 g) and KOH (29.19 g) (1:1 mol ratio) were added to a teflon beaker. Thie resulting mixture was heated to 175 °C with a heating mantle, stirred at 400 RPM, and electrolyzed for 47 minutes at -3.0 A using a Ti wire working electrode and Pt counter electrode of 4.7 cm2to eliminate water. Cyclic voltammograms were taken before and after the electrolysis step (FIG.5A). After electrolysis, a significant decrease in water splitting current was observed even at potentials 3 V more cathodic than before.

[0167] When the vigorous bubbling from the evolution of H2from the working electrode and O2 from the counter electrode decreased, the temperature was increased to 233 °C and 5.08 g of gibbsite powder was added. This material dissolved after several minutes and the electrode current was incrementally increased to -8.0 A. The resulting total cell voltages are in Table 1 below. Table 1. Cell Current / A Resulting Cell Voltage / V37 IPTS / 200004774.1Attorney Docket No: FEG-019WO decreasedaluminum species were a mix of aluminum oxides and reduced aluminum metal. Reduced aluminum deposits are shown in the SEM images in FIG 5B and FIG 5C. SEM imaging of the aluminum oxide deposits on the Ti electrode is shown in FIG.5D, which were much darker (i.e. less electron dense) than the Ti substrate and co-located with oxygen. EXAMPLE 11: Aluminum reduction from chloride baths at low temperatures

[0169] AlCl3 (38.29 g) NaCl (7.15 g), and KCl (7.57 g) (61 / 26 / 13 mol ratio) were added to a five-neck flask. The mixture was stirred and heated to 150 °C with a heating mantle to melt the mixture. Platinum coils each having a surface area of 4.7 cm2were inserted into the molten mixture as the working electrode and counter electrode. A rod formed from aluminum was inserted into the mixture as the reference electrode. The experimental apparatus is depicted in FIG.4A. Cyclic voltammograms were obtained between -0.5V and 3.5V as compared to the Al / AlCl3reference. An exemplary cyclic voltammogram is provided in FIG. 4B.

[0170] A voltage hold at -1V compared to Al / AlCl3reference was conducted for 1h at 150 °C while stirring to deposit Al metal on the Pt working electrode. A graph of the current as a function of time is provided in FIG.4C. After the voltage hold, the Pt electrode was rinsed with deionized water, dried, and analyzed via SEM-EDS at 15kV. Material deposition was observed, with the primary deposits being reduced aluminum, demonstrating reduction of AlCl3to aluminum, and aluminum oxide. SEM-EDS images of the deposits are provided in FIGs.4D-4F. EQUIVALENTS AND SCOPE

[0171] In the claims articles such as "a," "an," and "the" may mean one or more than one unless indicated to the contrary or otherwise evident from the context. Claims or descriptions 38 IPTS / 200004774.1Attorney Docket No: FEG-019WO that include "or" between one or more members of a group are considered satisfied if one, more than one, or all of the group members are present in, employed in, or otherwise relevant to a given product or process unless indicated to the contrary or otherwise evident from the context. Provide herein are embodiments in which exactly one member of the group is present in, employed in, or otherwise relevant to a given product or process. Provided herein are embodiments in which more than one, or all of the group members are present in, employed in, or otherwise relevant to a given product or process.

[0172] In the appended claims, the terms "including" and "in which" are used as the plain- English equivalents of the respective terms "comprising" and "wherein," respectively. Moreover, the terms "first," "second," "third," and so forth, are used merely as labels and are not intended to impose numerical requirements on their objects.

[0173] The foregoing description of examples has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the present disclosure be limited not by this detailed description, but rather by the claims appended hereto. Future filed applications claiming priority to this application may claim the disclosed subject matter in a different manner and may generally include any set of one or more limitations as variously disclosed or otherwise demonstrated herein.

[0174] Furthermore, the inventions provided herein encompass all variations, combinations, and permutations in which one or more limitations, elements, clauses, and descriptive terms from one or more of the listed claims is introduced into another claim. For example, any claim that is dependent on another claim can be modified to include one or more limitations found in any other claim that is dependent on the same base claim. Where elements are presented as lists, e.g., in Markush group format, each subgroup of the elements is also disclosed, and any element(s) can be removed from the group. It should be understood that, in general, where the inventions provided and described herein, or aspects of the inventions described and provided herein, is / are referred to as comprising particular elements and / or features, certain embodiments of the inventions or aspects of the inventions consist, or consist essentially of, such elements and / or features. For purposes of simplicity, those embodiments have not been specifically set forth in haec verba herein. It is also noted that the terms "comprising" and "containing" are intended to be open and permits the inclusion of additional elements or steps. Where ranges are given, endpoints are included. Furthermore, 39 IPTS / 200004774.1Attorney Docket No: FEG-019WO unless otherwise indicated or otherwise evident from the context and understanding of one of ordinary skill in the art, values that are expressed as ranges can assume any specific value or sub-range within the stated ranges in different embodiments of the inventions described and provided herein, to the tenth of the unit of the lower limit of the range, unless the context clearly dictates otherwise.

[0175] This application refers to various issued patents, published patent applications, journal articles, and other publications, all of which are incorporated herein by reference. If there is a conflict between any of the incorporated references and the instant specification, the specification shall control. In addition, any particular embodiment that falls within the prior art may be explicitly excluded from any one or more of the claims. Because such embodiments are deemed to be known to one of ordinary skill in the art, they may be excluded even if the exclusion is not set forth explicitly herein. Any particular embodiment can be excluded from any claim, for any reason, whether or not related to the existence of prior art.

[0176] Each numerical value presented herein is contemplated to represent a minimum value or a maximum value in a range for a corresponding parameter. Accordingly, when added to the claims, the numerical value provides express support for claiming the range, which may lie above or below the numerical value, in accordance with the teachings herein. Every value between the minimum value and the maximum value within each numerical range presented herein (including any minimum, nominal, and maximum values shown in any tables), is contemplated and expressly supported herein, subject to the number of significant digits expressed in each particular range. The application expressly contemplates the ranges between the minimum and nominal values, nominal and maximum values, and minimum and maximum values.

[0177] Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation many equivalents to the specific embodiments described herein. The scope of the present embodiments described herein is not intended to be limited to the above Description, but rather is as set forth in the appended claims. Those of ordinary skill in the art will appreciate that various changes and modifications to this description may be made without departing from the spirit or scope of the present inventions, as defined in the following claims. 40 IPTS / 200004774.1

Claims

Attorney Docket No: FEG-019WO CLAIMS:

1. A low temperature electrochemical method for producing aluminum metal, the method comprising: heating a low-melting electrolyte at or above its melting point in an electrolytic cell, thereby providing molten electrolyte in the electrolytic cell, wherein the electrolytic cell comprises an interior volume and one or more anodes and one or more cathodes, wherein the one or more anodes and one or more cathodes are each disposed within the interior volume, and wherein the molten electrolyte is disposed within the interior volume and is in contact with the one or more anodes and one or more cathodes; dissolving an oxidized aluminum feedstock in the molten electrolyte, thereby forming a molten mixture, wherein the molten mixture is in contact with the one or more cathodes and one or more anodes; reducing oxidized aluminum from the oxidized aluminum feedstock to produce aluminum metal at the one or more cathodes of the electrolytic cell by applying a voltage between the one or more cathodes and one or more anodes, wherein the temperature of the molten mixture is maintained at or above its melting point and equal to or below about 350 °C during the reduction, wherein an electrical current through the molten mixture is produced, wherein the electrical current causes the oxidized aluminum to be reduced at the one or more cathodes to form aluminum metal; and removing the aluminum metal from the electrolytic cell, thereby producing aluminum metal, wherein the melting point of the electrolyte is less than or equal to about 350 °C.

2. A low temperature electrochemical method for producing aluminum metal, the method comprising: heating a low-melting electrolyte at or above its melting point in an electrolytic cell, thereby providing molten electrolyte in the electrolytic cell, wherein the electrolytic cell comprises an interior volume and one or more anodes and one or more cathodes, wherein the one or more anodes and one or more cathodes are each disposed within the interior volume, and wherein the molten electrolyte is disposed within the interior volume and is in contact with the one or more anodes and one or more cathodes; 41 IPTS / 200004774.1Attorney Docket No: FEG-019WO adding an oxidized aluminum feedstock to the molten electrolyte, wherein the oxidized aluminum feedstock does not dissolve, and wherein the oxidized aluminum feedstock is in contact with the one or more cathodes; reducing oxidized aluminum from the oxidized aluminum feedstock to produce aluminum metal at the one or more cathodes of the electrolytic cell by applying a voltage between the one or more cathodes and one or more anodes, wherein the temperature of the molten electrolyte is maintained at or above its melting point and equal to or below about 350 °C during the reduction, wherein an electrical current through the molten electrolyte is produced, wherein the electrical current causes the oxidized aluminum to be reduced at the one or more cathodes to form aluminum metal; and removing the aluminum metal from the electrolytic cell, thereby producing aluminum metal, wherein the melting point of the electrolyte is less than or equal to about 350 °C.

3. The low temperature electrochemical method of claim 1 or 2, wherein the electrolytic cell further comprises thermal insulation.

4. The low temperature electrochemical method of any one of claims 1-3, wherein the electrolytic cell further comprises an external heating element and / or an internal heating element.

5. The low temperature electrochemical method of any one of claims 1-4, wherein the electrolytic cell comprises housing that is resistant to corrosion, e.g., from molten hydroxides.

6. The low temperature electrochemical method of claim 5, wherein the housing comprises PTFE, nickel, and / or PEEK.

7. The low temperature electrochemical method of any one of claims 1-6, wherein the method further comprises adding additional oxidized aluminum feedstock to the interior volume of the electrolytic cell to maintain feedstock concentration as oxidized aluminum is consumed.

8. The low temperature electrochemical method of claim 7, wherein the additional oxidized aluminum feedstock is added in batches. 42 IPTS / 200004774.1Attorney Docket No: FEG-019WO 9. The low temperature electrochemical method of claim 7, wherein the additional oxidized aluminum feedstock is added continuously.

10. The low temperature electrochemical method of any one of claims 7-9, wherein the electrolytic cell is hermetically sealed during addition of the additional oxidized aluminum feedstock.

11. The low temperature electrochemical method of any one of claims 7-10, wherein the additional oxidized aluminum feedstock is added using a load lock device to prevent exposure of the electrolytic cell to atmosphere.

12. The low temperature electrochemical method of any one of claims 1-11, wherein the electrolytic cell is connected to an intermittent energy supply that is used to supply the current and voltage to the electrolytic cell, heat the electrolytic cell, and / or maintain the temperature of the electrolytic cell.

13. The low temperature electrochemical method of claim 12, wherein the intermittent energy supply is a renewable energy source selected from electricity generated by solar panels and electricity generated by wind turbines.

14. The low temperature electrochemical method of claim 12 or 13, wherein the electrolytic cell is further connected to a second energy supply selected from the group consisting of an electrochemical battery, a heat battery, waste heat from another process, or a combination thereof, wherein the second energy supply sustains the electrolyte in a molten state when the intermittent energy supply is providing low or no power input.

15. The low-temperature electrochemical method of any one of claims 1-14, wherein the oxidized aluminum feedstock is Al(OH)3, AlOOH, or a mixture of Al(OH)3and AlOOH.

16. The low-temperature electrochemical method of claim 15, wherein the oxidized aluminum feedstock is Al(OH)3.

17. The low-temperature electrochemical method of any one of claims 1-14, wherein the oxidized aluminum feedstock is Al2S3. 43 IPTS / 200004774.1Attorney Docket No: FEG-019WO 18. The low-temperature electrochemical method of claim 17, wherein the Al2S3has been produced from a reaction of Al(OH)3and / or AlOOH with sulfur and / or H2S, wherein the Al(OH)3 and / or AlOOH are byproducts of an aluminum-water reaction.

19. The low-temperature electrochemical method of any one of claims 1-14, wherein the oxidized aluminum feedstock is AlCl3, AlI3, or a mixture of AlCl3and AlI3.

20. The low-temperature electrochemical method of claim 19, wherein the oxidized aluminum feedstock is AlCl3.

21. The low-temperature electrochemical method of claim 20, wherein the AlCl3has been produced from a reaction of Al(OH)3 and / or AlOOH with chlorine and / or HCl, wherein the Al(OH)3 and / or AlOOH are byproducts of an aluminum-water reaction.

22. The low-temperature electrochemical method of claim 19, wherein the oxidized aluminum feedstock is AlI3.

23. The low-temperature electrochemical method of claim 22, wherein the AlI3 has been produced from a reaction of Al(OH)3and / or AlOOH with iodine and / or HI, wherein the Al(OH)3 and / or AlOOH are byproducts of an aluminum-water reaction.

24. The low-temperature electrochemical method of any one of claims 1-14, wherein the oxidized aluminum feedstock is Al2(SO4)3, KAl(SO4)2, NaAl(SO4)2, or a mixture of Al2(SO4)3 and KAl(SO4)2.

25. The low-temperature electrochemical method of claim 24, wherein the Al2(SO4)3has been produced from a reaction of Al(OH)3 and / or AlOOH with SO3, either directly or with H2SO4as an intermediate, wherein the KAl(SO4)2has been produced from a reaction of the Al2(SO4)3 with K2SO4, wherein the NaAl(SO4)2 has been produced from a reaction of the Al2(SO4)3with Na2SO4, and wherein the Al(OH)3and / or AlOOH are byproducts of an aluminum-water reaction.

26. The low-temperature electrochemical method of any one of claims 1-25, wherein the oxidized aluminum feedstock is at least 95% pure. 44 IPTS / 200004774.1Attorney Docket No: FEG-019WO 27. The low temperature electrochemical method of any one of claims 1-26, wherein the low-melting electrolyte is a low temperature molten salt (LTMS) electrolyte based on a binary, ternary, quaternary, or other mixture of chloride and / or other halide (F, Cl, Br, I) salts.

28. The low temperature electrochemical method of claim 27, wherein the LTMS is 41 mole percent AlCl3and 59 mole percent NaCl (Tm~150 °C).

29. The low temperature electrochemical method of claim 27, wherein the LTMS is 61 mole percent AlCl3and 39 mole percent NaCl (Tm=102 °C).

30. The low temperature electrochemical method of claim 27, wherein the LTMS is 61 mole percent AlF3 and 39 mole percent NaCl.

31. The low temperature electrochemical method of claim 27, wherein the LTMS is 61 mole percent AlI3 and 39 mole percent NaCl.

32. The low temperature electrochemical method of claim 27, wherein the LTMS is 61 mole percent AlBr3 and 39 mole percent NaCl.

33. The low temperature electrochemical method of claim 27, wherein the LTMS is about 54.6 mole percent AlCl3, about 19.1 mole percent LiCl, about 19.5 mole percent NaCl, and about 6.8 mole percent KCl (Tm=85 °C).

34. The low temperature electrochemical method of claim 27, wherein the LTMS is about 54.6 mole percent AlF3, about 19.1 mole percent LiCl, about 19.5 mole percent NaCl , and about 6.8 mole percent KCl.

35. The low temperature electrochemical method of claim 27, wherein the LTMS is about 54.6 mole percent AlI3, about 19.1 mole percent LiCl, about 19.5 mole percent NaCl, and about 6.8 mole percent KCl.

36. The low temperature electrochemical method of claim 27, wherein the LTMS is about 54.6 mole percent AlBr3, about 19.1 mole percent LiCl, about 19.5 mole percent NaCl, and about 6.8 mole percent KCl.

37. The low temperature electrochemical method of claim 27, wherein the LTMS is about 61 mole percent AlCl3, about 26 mole percent NaCl, and about 13 mole percent KCl. 45 IPTS / 200004774.1Attorney Docket No: FEG-019WO 38. The low temperature electrochemical method of any one of claims 1-26, wherein the low-melting electrolyte is a sulfate based electrolyte.

39. The low temperature electrochemical method of claim 38, wherein the sulfate based electrolyte is KAl(SO4)2 (Tm=92-95 °C).

40. The low temperature electrochemical method of claim 38, wherein the sulfate based electrolyte is Al2(SO4)3 (Tm= 86.5 °C (octadecahydrate)).

41. The low temperature electrochemical method of claim 38, wherein the sulfate based electrolyte is a binary, ternary, quaternary, or other mixture of sulfate salts, wherein at least one sulfate salt contains aluminum as a working ion.

42. The low temperature electrochemical method of any one of claims 1-26, wherein the low-melting electrolyte is a low temperature molten salt (LTMS) electrolyte based on a binary, ternary, quaternary, or other mixture of metal hydroxide compounds.

43. The low temperature electrochemical method of claim 42, wherein the LTMS is a binary mixture of NaOH and KOH.

44. The low temperature electrochemical method of claim 42, wherein the LTMS is about 51.5 mole percent NaOH and about 48.5 mole percent KOH.

45. The low temperature electrochemical method of claim 42, wherein the LTMS is about 50 mole percent NaOH and about 50 mole percent KOH.

46. The low temperature electrochemical method of claim 42, wherein the LTMS is a binary mixture of CsOH and NaOH.

47. The low temperature electrochemical method of claim 42, wherein the LTMS is about 48 mole percent CsOH and about 52 mole percent NaOH (Tm=155 °C).

48. The low temperature electrochemical method of any one of claims 42-47, wherein the LTMS comprises metal cations, and the metal cations have reduction potentials lower than Al3+. 46 IPTS / 200004774.1Attorney Docket No: FEG-019WO 49. The low temperature electrolytic method of any one of claims 27-41, wherein the electrolytic cell is hermetically sealed, thereby preventing evaporation of aluminum- containing salts (e.g., AlCl3).

50. The low temperature electrochemical method of any one of claims 1-49, wherein the temperature of the molten electrolyte is maintained at about 100 °C after initial heating.

51. The low temperature electrochemical method of any one of claims 1-49, wherein the temperature of the molten electrolyte is maintained below about 170 °C after initial heating.

52. The low temperature electrochemical method of any one of claims 1-49, wherein the temperature of the molten electrolyte is maintained below about 175 °C after initial heating.

53. The low temperature electrochemical method of any one of claims 1-49, wherein the temperature of the molten electrolyte is maintained below about 200 °C after initial heating.

54. The low temperature electrochemical method of any one of claims 1-49, wherein the temperature of the molten electrolyte is maintained below about 350 °C after initial heating.

55. The low temperature electrochemical method of any one of claims 1-54, wherein the one or more anodes are non-carbon anodes that do not emit CO2as an oxidation product.

56. The low temperature electrochemical method of any one of claims 1-55, wherein the mass ratio of low-melting electrolyte to oxidized aluminum feedstock compound in the electrolytic cell is 999:1, 99:1, 95:5, 90:10, 80:20, 75:25, 67:33, or 50:

50.

57. The low temperature electrochemical method of any one of claims 1-56, wherein removing the aluminum metal from the electrolytic cell comprises periodically removing the one or more cathodes after reducing oxidized aluminum for a specified period of time (e.g., every 1 hour, 12 hours, 1 day, or 1 week), wherein solid aluminum is deposited on the surface of the one or more cathodes.

58. The method of any one of claims 1-56, wherein removing the aluminum comprises heating the electrolytic cell above the melting temperature of aluminum (660 °C), thereby allowing liquid aluminum to flow to the bottom of the electrolytic cell, and removing the liquid aluminum via an outlet at the bottom of the electrolytic cell, or with the assistance of a vacuum, or a combination of both. 47 IPTS / 200004774.1

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