WO2024054649A1 - Solid state rare earth metal electrolytic production cell and related systems and methods - Google Patents

Abstract

The present disclosure is related to solid state rare earth metal electrolytic production cell.

Description

SOLID STATE RARE EARTH METAL ELECTROLYTIC PRODUCTION CELL AND RELATED SYSTEMS AND METHODS

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63/405,287, filed September 9, 2022, and entitled “SOLID STATE RARE EARTH METAL ELECTROLYTIC PRODUCTION CELL AND RELATED SYSTEMS AND METHODS,” which is incorporated herein by reference in its entirety for all purposes.

TECHNICAL FIELD

Solid state rare earth metal electrolytic production cells, and related systems and methods, are generally described.

SUMMARY

The present disclosure is related to solid state rare earth metal electrolytic production cells and related systems and methods. The subject matter of the present invention involves, in some cases, interrelated products, alternative solutions to a particular problem, and/or a plurality of different uses of one or more systems and/or articles.

Certain aspects are related to methods.

In some embodiments, the method comprises within an electrolytic cell comprising a cathode, an anode, and an electrolyte having a volume, electroplating a target metal within the volume of the electrolyte onto the cathode and/or the anode; wherein the electrolyte comprises at least two halogens.

Certain aspects are related to electrolytic cells.

In some embodiments, the electrolytic cell comprises a cathode; an anode; and an electrolyte comprising at least two halogens; wherein the electrolytic cell is configured to electroplate, on the cathode and/or the anode, a target metal from a volume of the electrolyte.

Other advantages and novel features of the present invention will become apparent from the following detailed description of various non-limiting embodiments of the invention when considered in conjunction with the accompanying figures. In cases where the present specification and a document incorporated by reference include conflicting and/or inconsistent disclosure, the present specification shall control.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale unless otherwise indicated. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention. In the figures:

FIGS. 1-3 are, in accordance with certain embodiments, cross-sectional schematic illustrations showing a system for electroplating a target metal.

DETAILED DESCRIPTION

Solid state rare earth metal electrolytic production cells, and related systems and methods, are generally described. Certain aspects of the present disclosure are directed to the discovery that the use of certain molten salts (e.g., as electrolytes) can allow for efficient electroplating of at least one target metal from materials containing the target metal and one or more other materials (e.g., a halogen species). Certain embodiments are related to the discovery that the use of a molten salt melt comprising mixed halogens (e.g., at least two different halogens) and/or at least two metals may lead to efficient electroplating of the target metal. For example, the use of a molten salt comprising a particular composition of target metal, at least one alkali metal and/or an alkaline earth metal, and at least two halogens can provide, in certain instances, one or more of a variety of operational advantages including, but not limited to, selective electroplating of target metal(s) (e.g., transitional metal(s) or rare earth metal(s)) relative to non-target- metal(s) (e.g., alkali metal(s) or alkaline earth metal(s)); lower operating temperature; reduced gas formation (e.g., little to none CO2 emission); and/or the ability to achieve a relatively high yield of target metal in the form of a high-purity solid (e.g., such as a yield of greater than 1 gram and/or a purity of greater than 90 wt%). Some embodiments are related to the discovery that effective electroplating can be achieved for rare earth meals (e.g., heavy rare earth metals) using the molten salt melt as an electrolyte in an electrolytic cell described herein. It has also been recognized, within the context of the present disclosure, that the electrolytic cell described herein can be operated continuously, which can have a number of advantageous effects including, in certain cases, enhanced process efficiency and/or higher yield of target metal.

In some embodiments, methods are provided. The methods can involve, in some embodiments, exposing a target-metal-containing material to an electrolyte within an electrolytic cell. The target metal, in some embodiments, may be electroplated onto the cathode and/or anode. In some embodiments, electrolytic cells are provided. The electrolytic cells may be employed to electroplate a target metal from a target metalcontaining material.

FIGS. 1-3 are schematic illustrations of one such electrolytic cell that can be used to electroplate target metal from a target-metal-containing material. These figures are referred to throughout the disclosure below.

In some embodiments, an electrolytic cell is provided. The term “electrolytic cell,” as used herein, refers to a device in which electrical energy is input into the device to drive a non- spontaneous redox reaction. The electrolytic cell, according to some embodiments, comprises a cathode, an anode, and an electrolyte. In some embodiments, the anode and cathode may be at least partially immersed in the electrolyte. A nonlimiting example of one such electrolytic cell is shown in FIG. 1. As shown, electrolytic cell 102 comprises cathode 106, anode 104, and electrolyte 108. Cathode 106 and anode 104 may be at least partially immersed in electrolyte 108. Typically, operation of the electrolytic cell proceeds as follows. A source of electrical energy (e.g., source 110 in FIG. IB) can be connected to the anode and the cathode, and electrical energy from the source can be used to drive a nonspontaneous redox reaction between the anode and the cathode. The source of electrical energy (e.g., an AC power source, a battery, or any other suitable source) can be used to generate a potential difference between the anode and the cathode that forces electrons to flow from the anode to the cathode, which drives the nonspontaneous redox reaction. At the anode, an oxidation half reaction generally occurs, whereas at the cathode, a reduction half-reaction generally occurs. The electrolyte is generally used to facilitate the transport of ions between the anode and the cathode, which balances the charges within the cell as electrons are transported between the anode and the cathode.

A variety of types of materials can be used as the anode, the cathode, and the electrolyte of the electrolytic cell, and the selection of these materials generally depends on the type of redox reaction that is being driven by the electrolytic cell. Examples of materials from which the anode can be made include, but are not limited to, carbon (e.g., graphitic carbon such as graphene, graphite, carbon nanotubes, glassy carbon and the like). Examples of materials from which the cathode can be made include, but are not limited to, refractory metals such as titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), zirconium (Zr), niobium (Nb), molybdenum (Mo), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), ruthenium (Ru), rhodium (Rh), technetium (Tc), and hafnium (HF).

In some embodiments, the electrolytic cell is configured to electroplate a target metal from a volume of the electrolyte. For example, referring to FIG. 1, electrolytic cell 102 is configured to electroplate a target metal from a volume of electrolyte 108. In one set of embodiments, the target metal comprises a transition metal. The “transition metals,” as used herein, are scandium (Sc), yttrium (Y), lanthanum (Fa), actinium (Ac), titanium (Ti), zirconium (Zr), hafnium (Hf), rutherfordium (Rf), vanadium (V), niobium (Nb), tantalum (Ta), dubnium (Db), chromium (Cr), molybdenum (Mo), tungsten (W), seaborgium (Sg), manganese (Mn), technetium (Tc), rhenium (Re), bohrium (Bh), iron (Fe), ruthenium (Ru), osmium (Os), hassium (Hs), cobalt (Co), rhodium (Rh), iridium (Ir), meitnerium (Mt), nickel (Ni), palladium (Pd), platinum (Pt), darmstadtium (Ds), copper (Cu), silver (Ag), gold (Au), roentgenium (Rg), zinc (Zn), cadmium (Cd), mercury (Hg), and copernicium (Cn). In some embodiments, the target metal within the target-metal-containing material comprises a transition metal that is not a platinum group metal (PGMs). As used herein, the “platinum group metals” are platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), osmium (Os), and ruthenium (Ru). In some embodiments, the target metal within the target-metal-containing material comprises a transition metal that is not gold (Au) or silver (Ag).

In some embodiments, the target metal may be contained within the electrolyte. In some cases, the target metal may be contained within the electrolyte in the form of a metal cation. The target metal within the electrolyte, according to some embodiments, may be initially present within the electrolyte and/or later introduced into the electrolyte from a target-metal-containing material during operation of the electrolytic cell.

In some embodiments, the target metal present within the target-metal-containing material comprises a rare earth metal. The rare earth metal, according to some embodiments, is a light rare earth metal or a heavy earth metal. The “light rare earth metals,” as used herein, are cerium (Ce), lanthanum (La), praseodymium (Pr), neodymium (Nd), promethium (Pm), europium (Eu), gadolinium (Gd), and samarium (Sm). The “heavy rare earth metals,” as used herein, are dysprosium (Dy), yttrium (Y), terbium (Tb), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), yttrium (Y), and lutetium (Lu).

In some embodiments, the target-metal containing material comprises a target metal and a halogen. For the purpose of the present disclosure, the “halogen” elements are fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). The halogen may be in any of a variety of forms, such as in elemental, binary, or ionic form. In one embodiment, the halogen may be present as part of a halogen salt, such as in the form of a halide. In some cases, the target-metal containing material may be a halogen salt comprising a target metal cation and a halide. For example, the target-metal containing material may be a rare earth metal halide and/or a transition metal halide. The target metal cation within the target-metal containing material may have any appropriate oxidation states, e.g., such as +2, +3, +4, +5, +6, etc. Non-limiting examples of transition metal halides includes transition metal chloride (e.g., C0CI2, NiCh, FeCh). Non-limiting examples of rare earth metal halides include rare earth metal chlorides (e.g., DyCl₃, H0CI3, TeCl₃, etc.).

In some embodiments, the electrolyte comprises at least two halogens. An electrolyte comprising at least two halogens may refer to an electrolyte comprising two types of halogen elements, such as including a first halogen element and at least one other halogen element different from the first halogen element. For example, in one set of embodiments, the at least two halogens comprise F and Cl. In some embodiments, one or more of the at least two halogens are in the forms of halide(s). In some embodiments, each of the at least two halogens is in the form of a halide. For example, according to some embodiments, the at least two halides comprise a fluoride and a chloride. In one set of embodiments, the electrolyte comprises molten salt(s) comprising at least two halogens. The molten salt(s), in some embodiments, comprises molten halogen salt(s). A “halogen salt” is any salt that contains a halogen atom. The halogen salt(s), according to some embodiments, may be a single halogen salt or a combination of multiple halogen salts. In accordance with certain embodiments, it can be advantageous to use particular combinations of halogen salts (e.g., molten halogen salts) comprising at least two halogens to achieve desired molten salt bath characteristics, enhanced processing efficiencies, and/or other advantages. In some embodiments, the molten salt(s) is a eutectic mixture.

Those of ordinary skill in the art would understand that a molten salt is a liquidphase salt, as opposed to a solubilized salt (which refers to a salt that has been solubilized into its constituent ions within a solvent). In some embodiments, the molten salt is a salt that is in a solid phase when at a temperature of 25°C and a pressure of 1 atmosphere but that melts to form a liquid phase when heated to or above its melting point.

In some embodiments, the electrolyte may comprise molten halogen salt(s) comprising at least two metals. For example, in one set of embodiments, the at least two metals comprise a target metal, along with at least one metal that is an alkali metal and/or an alkaline earth metal. The term “alkali metal” is used herein to refer to the following six chemical elements of Group 1 of the periodic table: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). The term “alkaline earth metal” is used herein to refer to the six chemical elements in Group 2 of the periodic table: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). In some embodiments, the use of calcium, strontium, and/or magnesium can be particularly advantageous. The target metal may be any of a variety of transition metals and/or rare earth metals described elsewhere herein.

The halogen salt(s), in some embodiments, may comprise at least one selected from alkali metal halide and alkaline earth metal halide and at least one halide of the target metal. Non-limiting examples of alkali metal halide include NaCl, KC1, NaF, KF, LiCl, and/or LiF. Non-limiting examples of alkaline earth metal halide include CaCh, MgCh, MgF2, CaF2, SrCh, SrF2, CaBn. Non-limiting examples of a halide of the target metal include a transition metal chloride or fluoride (e.g., FeCL) and/or a rare earth metal chloride(e.g., DyCF, H0CI3, TeCF, etc.). The use of at least one halide of the target metal in the electrolyte may impart the electrolytic cell with certain advantages, such as (i) preventing the electroplating of undesirable non-target metals (e.g., alkali metals and/or alkaline earth metals) from the electrolyte during electroplating, and/or (ii) more efficient electroplating of the target metals.

In accordance with certain embodiments, the electrolyte comprises molten halogen salt(s) comprising at least two halogens (e.g., a chloride and a fluoride). The presence of a mixture of at least two halogens may impart the electrolyte with certain advantages, such as a more thermodynamically stable electrolyte composition with enhanced electroplating and/or extraction capabilities for a target metal. The halogen salt(s), in some instances, may comprise a metal chloride and/or a metal fluoride. Nonlimiting examples of metal chlorides include alkali metal chlorides or alkaline earth metal chlorides (e.g., NaCl, KC1, LiCl, CaCh ), chlorides of a target metal (e.g., a transition metal chloride (e.g., FeCh), and rare earth metal chlorides (e.g., DyCh, H0CI3, TeCh)). Non-limiting examples of metal fluorides include alkali metal fluorides and/or alkaline earth metal fluorides (e.g., LiF, NaF, KF), fluorides of a target metal (e.g., a transition metal fluoride, and rare earth metal fluorides). In some embodiments, the electrolyte comprises halogen salt(s) comprising an alkali and/or alkaline earth metal chloride and an alkali and/or alkaline earth metal fluoride.

In some embodiments, the electrolyte may comprise a particular combination of halogen salt(s) comprising at least two halogens and at least two metals. For example, the at least two metals may comprise a metal that is an alkali metal or alkaline earth metal and a target metal (e.g., a transition metal and/or a rare earth metal). The at least two halogens may comprise a fluoride and a chloride. For example, in one set of embodiments, the halogen salt(s) may comprise at least one selected from an alkali metal halide and an alkaline earth metal halide (e.g., alkali or alkaline earth metal chloride, alkali or alkaline earth metal fluoride) and a halide of the target metal (e.g., chloride of the target metal). The use of such a combination of halogen salt(s) in the electrolyte, when in the form of a molten halogen salt(s), may lead to a more thermodynamically stable electrolyte composition with enhanced electroplating capabilities for a target metal, and may prevent undesirably electroplating of non-target metals (e.g., alkali metal and/or alkaline earth metal) from the electrolyte during electroplating. In some embodiments in which the electrolyte (e.g., molten halogen salt(s)) comprises a first halogen (e.g., Cl) and a second halogen (e.g., F), the atomic ratios of the total amount of the first halogen to the total amount of the second halogen may have any of a variety of values. In some embodiments, the atomic ratios of the total amount of a first halogen (e.g., Cl) to the total amount of a second halogen (e.g., F) may be greater than or equal to 1:3, greater than or equal to 1:2, greater than or equal to 2:3, greater than or equal to 1:1, greater than or equal to 3 :2, or greater than or equal to 2: 1. In some embodiments, the atomic ratios of the total amount of a first halogen (e.g., Cl) to the total amount of a second halogen (e.g., F) may be less than or equal to 3:1, less than or equal to 2:1, less than or equal to 3:2, less than or equal to 1:1, less than or equal to 2:3, or less than or equal to 1:2. Combinations of the above-referenced ranges are possible (e.g., greater than or equal to 1:3 and less than or equal to 3:1). Other ranges are also possible.

In some embodiments, the atomic ratio of the total amount of target metals (e.g., target metal cations) to the total amount of alkali metal(s) and/or alkaline earth metal(s) (e.g., alkali metal cations and/or alkaline earth metal cations) in the electrolyte may be greater than or equal to 1:10, greater than or equal to 1:7, greater than or equal to 1:4, greater than or equal to 1:3, greater than or equal to 1:2, greater than or equal to 2:3, greater than or equal to 1:1, greater than or equal to 3:2, greater than or equal to 2:1, greater than or equal to 3 : 1 , greater than or equal to 4: 1 , or greater than or equal to 7: 1.

In some embodiments, during operation of the electrolytic cell, the atomic ratios of the target metals (e.g., target metal cations) to alkali and/or alkaline earth metals (e.g., alkali metal cations and/or alkaline earth metal cations) in the electrolyte may be less than or equal to 10:1, less than or equal to 7:1, less than or equal to 4:1, less than or equal to 3:1, less than or equal to 2:1, less than or equal to 3:2, less than or equal to 1:1, less than or equal to 2:3, less than or equal to 1:2, less than or equal to 1:4, or less than or equal to 1:7. Combinations of the above-referenced ranges are possible (e.g., greater than or equal to 1:10 and less than or equal to 10:1, or greater than or equal to 1:7 and less than or equal to 4:1). Other ranges are also possible.

In some embodiments, the electrolytic cell may be a sealed volume (e.g., as shown in FIG. 1). The electrolytic cell may, in some embodiments, contain an inert gas. According to some embodiments, the inert gas is configured to occupy any volume not occupied by the electrolyte. For example, as shown in FIG. 1, volume 109 may contain an inert gas. The gas can be, in some embodiments, an inert gas with respect to the electrolyte, target metal, and/or target-metal-containing material within the electrolytic cell. A variety of gases can be used in the systems and methods described herein. As noted above, the gas can be inert with respect to the molten metal within the reactor (and/or to other components), in some embodiments. In some embodiments, the inert gas comprises a noble gas. In some embodiments, the inert gas comprises helium, neon, argon, krypton, and/or xenon. In some embodiments, the use of helium, neon, argon, and/or krypton is advantageous. In certain embodiments, the use of argon is advantageous. It should be understood that other inert gases could also be used, and the selection of an appropriate inert gas will generally involve selecting a gas that does not chemically react with the molten metal or reacts with the molten metal only to a limited degree (e.g., to a degree sufficiently low to allow for the production of metal having the purities described elsewhere herein). Other gases that can be used include, but are not limited to nitrogen (N2) and carbon dioxide. In some embodiments, the gas contains little or no oxygen. For example, in some embodiments, the gas (e.g., inert gas) has an oxygen content of less than or equal to 5 mol%, less than or equal to 2 mol%, less than or equal to 1 mol%, less than or equal to 0.1 mol%, less than or equal to 0.01 mol%, less than or equal to 0.001 mol%, less than or equal to 0.0001 mol%, less than or equal to 0.00001 mol%, less than or equal to 0.000001 mol%, less than or equal to 0.0000001 mol%, or less.

The electrolytic cells may be optionally associated with any of a variety of appropriate components (e.g., a container, valves, regulators, source of inert gas, heater, etc.). In certain embodiments, the electrolytic cells may comprise an opening fluidically connected to a source of a gas (e.g., a tank or other container containing pressurized gas). One such example of this arrangement is shown in FIG 1. As shown in FIG. 1, for example, in system 100, volume 109 in electrolytic cell 102 is fluidically connected to gas source 130 (e.g., a source of an inert gas) via opening 121, conduit 124, and conduit 132. In some embodiments, a negative pressure source may be connected to the electrolytic cell. As shown in FIG. 1., a negative pressure source 122 and gas source 130 are fluidically connected to volume 109 via opening 121. In such embodiments, opening 121 can be used as both an inlet into volume 109 (e.g., when gas is transported from gas source 130 into volume 109, for example, as described in more detail below) and an outlet from volume 109 (e.g., when negative pressure source 122 is used to remove gas or other materials from volume 109). In other embodiments, the opening of the conduit the that is fluidically connected to the source of the inert gas is different from the opening of the electrolytic cell that is fluidically connected to the source of negative pressure.

In some embodiments, the system may optionally comprise a regulator configured to control gas flow into and out of the electrolytic cell. For example, the system may comprise a regulator between the gas source and the volume within the electrolytic cell, such as in position 134 of FIG. 1 that is configured to control the amount of gas supplied to the volume. Additionally or alternatively, in some embodiments, the system comprises a regulator (e.g., between the negative pressure source and the volume, such as in position 128 of FIG. 1) that is configured to control the degree of negative pressure applied by the negative pressure source to the volume.

In some embodiments, the electrolytic cell may be associated with a heater configured to heat the electrolytic cell to a temperature (e.g., to a temperature described herein). The heater may include any of a variety of heating systems (e.g., such as an internal or an external heating systems). Examples of heater include, but are not limited to, a Peltier heater, a heating jackets and/or coils, a resistive heater, a microwave, and/or a gas burner. Referring to FIG. 1, in system 100, electrolytic cell 102 may be associated with an external heater (not shown), e.g., such as a resistive heater.

In some embodiments, the electrolytic cell may be fluidically connected to a source of target- metal-containing material. For example, as shown in FIG. 1, electrolytic cell 102 may be fluidically connected to source 135 containing target- metal-containing materials via opening 123 and conduit 125. In some embodiments, the source of target- metal-containing material may be a hermetically sealed hopper connected to a source of inert gas (e.g., argon gas). During operation, a flow of inert gas may be used to transport the target metal-containing materials into the electrolytic cell. In other embodiments, the opening of the conduit that is fluidically connected to the source of target-metal- containing material may be the same as the opening that is fluidic connected to the source of the inert gas and/or the source of negative pressure. For example, the electrolytic cell may be fluidically connected to the source containing target-metal- containing material via opening 121 and conduit 124. Optional regulators may also be present to control the feed rate and amount of the target-metal-containing material fed to the volume. In accordance with certain embodiments, during operation of the electrolytic cell, target-metal-containing materials may be introduced into the electrolytic cell as desired.

The electrolytic cell can comprise, in accordance with certain embodiments, a container (e.g., a crucible). In FIG. 1, for example, electrolytic cell 102 comprises container 112. The container can contain, in some embodiments, an anode, a cathode, and an electrolyte. The container may also contain other components of the system, as described in more detail below. The container can have any of a variety of suitable sizes. In some embodiments, the container has an interior volume of at least 500 cm³; at least 1000 cm³; at least 10,000 cm³; at least 100,000 cm³; at least 1 m³; or at least 10 m³ (and/or up to 100 m³; up to 1000 m³; up to 10,000 m³; or greater).

In some embodiments, a method is provided. In one set of embodiments, the method is a method for electroplating a target metal within a volume of the electrolyte. The target metal within the electrolyte, according to some embodiments, may include any target metal originally present within the electrolyte and/or any target metal introduced to the electrolyte from target-metal-containing materials during operation of the electrolytic cell. Any of the electrolytic cells described herein (or other cells) may be employed to carry out the method provided herein.

In some embodiments, the method comprises providing an electrolyte comprising molten salt(s) (e.g., molten halogen salt(s)) within the electrolytic cell. According to some embodiments, the molten salts may be prepared by heating initially solid salt(s) (e.g., solid halogen salt (s)) such that at least a portion of the solid salt melts and forms a fluid phase. FIG. 1 illustrates an electrolyte that is part of a molten salt bath within electrolytic cell 102. As shown in FIG. 1, electrolyte 108 may be prepared by heating initially solid halogen salt(s) above their melting point, causing the formation of a molten bath comprising molten salt(s) (e.g., molten halogen salt(s)) within cell 102. The molten bath may be formed either within the electrolytic cell, e.g., via heating of the electrolytic cell, or may be formed externally and subsequently transferred to the electrolytic cell. The electrolyte and/or halogen salt(s) may have any of a variety of compositions described elsewhere herein. For example, in some embodiments, the solid halogen salt(s) comprises a combination of at least one salt containing a first halogens (e.g., F) and at least one salt containing a second halogens (e.g., Cl). In one set of embodiments, the solid halogen salt(s) comprises at least one solid alkali and/or alkaline earth metal fluoride salt (e.g., NaF, LiF, KF, etc.), at least one solid alkali and/or alkaline earth metal fluoride salt (e.g., NaCl, KC1, LiCl, etc.), and a solid chloride salt comprising the target metal (e.g., transition metal or rare earth metal chloride). During heating, the solid halogen salt(s) is heated to a temperature such that the solid halogen salt(s) forms a molten salt bath. The solid halogen salt(s) may be heated to a temperature of greater than or equal to 100 °C, greater than or equal to 250 °C, greater than or equal to 350 °C, greater than or equal to 500 °C, greater than or equal to 800 °C, greater than or equal to 900 °C, or more, and/or less than or equal to 1000 °C, less than or equal to 900 °C, less than or equal to 800 °C, less than or equal to 500 °C, less than or equal to 350 °C, less than or equal to 250 °C, or less. Combinations of the above-referenced ranges are possible (e.g., greater than or equal to 100 °C and less than or equal to 1000 °C, greater than or equal to 250 °C and less than or equal to 900 °C, or greater than or equal to 350 °C and less than or equal to 800 °C). The solid molten salt(s) may be heated for any appropriate period of time (e.g., between 0.25 hours to 10 hours, between 2 hours to 8 hours, or between 3 hours to 6 hours).

The solid halogen salt(s), prior to being used to form the molten bath, may be pretreated to remove undesirable moisture and/or volatiles. For example, in some embodiments, solid halogen salt(s) (e.g., a fluoride salt, an alkali and/or alkaline earth metal chloride salt, etc.) may be dried under air or vacuum at any of a variety of temperatures (e.g., between 75 °C and 600 °C, between 100 °C and 400 °C, between 150 °C and 250 °C) for any of a variety of suitable period of time (e.g., between 0.5 hours and 12 hours, between 2 hours and 8 hours, or between 4 and 6 hours, etc.). In some embodiments, solid halogen salt(s) comprising a target metal (e.g., transition metal chloride and/or rare earth metal chloride) may be dried under air or vacuum at any of a variety of temperatures (e.g., between 75 °C and 800 °C, between 125 °C and 600 °C, between 200 °C and 400 °C) for any of a variety of suitable periods of time (e.g., between 0.5 hours and 12 hours, between 2 hours and 8 hours, or between 4 hours and 6 hours, etc.). In some embodiments, the molten salt may be prepared under an inert atmosphere. Any appropriate inert gas described herein may be employed.

In some embodiments, the method comprises exposing a target-metal-containing material to a volume of the electrolyte within the electrolytic cell. For example, referring to FIG. 2, during operation of electrolytic cell 102, target-metal-containing material(s) 107 may be introduced to and exposed to a volume of electrolyte 108 from source 135 of target-metal-containing materials via opening 123 and conduit 125. Any of a variety of target-metal-containing materials described herein may be used. For example, as noted elsewhere herein, the target-metal-containing materials may comprise a halogen salt comprising a target metal cation and a halide anion (e.g., a rare earth metal halide and/or a transition metal halide).

In some embodiments, upon exposing the target-metal-containing material(s) to the electrolyte (e.g., a molten halogen salt bath), at least a portion of the target-metal- containing material(s) may subsequently melt and occupy a volume of the electrolyte. For example, at least 50 wt% (e.g., at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 99 wt%, or all) of the target- metal-containing(s) may melt an occupy a volume electrolyte.

In some embodiments, the target-metal-containing material may be periodically or continuously added to the electrolyte as desired to maintain a particular atomic ratio of total amount of target metals (e.g., target metal cations) to total amount of alkali metals and/or alkaline earth metals (e.g., alkali metal cations and/or alkaline earth metal cations) within the electrolyte. In some cases, it may be particularly advantageous to maintain the atomic ratio of total amount of target metals (e.g., target metal cations) in the electrolyte to the total amount of alkali metals and/or alkaline earth metals (e.g., alkali metal cations and/or alkaline earth metal cations) within a certain range to allow for efficient electroplating of the target metals. For example, when the atomic ratio of the total amount of target metals (e.g., target metal cations) in the electrolyte to the total amount of alkali metals and/or alkaline earth metals (e.g., alkali or alkaline earth metal cations) is undesirably low, unwanted electroplating of non-target metals (e.g., alkali or alkaline earth metals) from the electrolyte may occur. Conversely, when the atomic ratio of the total amount of target metals (e.g., target metal cations) in the electrolyte to the total amount of alkali and/or alkaline earth metals (e.g., alkali and/or alkaline earth metal cations) is undesirably high, unwanted solubilization of the electroplated target metal(s) (e.g., rare earth metal(s)) within the electrolyte (e.g., molten halogen salt(s)) may occur. The aforementioned undesirable electroplating of non-target metal and/or solubilization of the electroplated target metal may result in reduced cell life and performance, as well as a lower yield and purity of the electroplated target metals.

In some embodiments, during operation of the electrolytic cell, the atomic ratio of the total amount of target metal (e.g., target metal cations) in the electrolyte to the total amount of alkali metal and/or alkaline earth metal (e.g., alkali metal cation and/or alkaline earth metal cation) in the electrolyte (at any given time) can have any of a variety of values. In some embodiments, the total amount of target metals (e.g., target metal cations) may include the amount of target metal originally present in the electrolyte and any target metals present within the target-metal-containing materials introduced into the electrolyte while operating the electrolytic cell. For example, in some embodiments, the atomic ratio of the total amount of target metal cations to the total amount of alkali and/or alkaline earth metal cation in the electrolyte at one or more times (e.g., during at least 50%, at least 75%, at least 90%, at least 95%, or at least 99% of the time) during which the electrolytic reaction is performed may be greater than or equal to 1:10, greater than or equal to 1:7, greater than or equal to 1:4, greater than or equal to 1:3, greater than or equal to 1:2, greater than or equal to 2:3, greater than or equal to 1:1, greater than or equal to 3:2, greater than or equal to 2:1, greater than or equal to 3 : 1 , greater than or equal to 4: 1 , or greater than or equal to 7: 1. In some embodiments, the atomic ratio of the total amount of target metal cations to the total amount of alkali and/or alkaline earth metal cations in the electrolyte at one or more times (e.g., during at least 50%, at least 75%, at least 90%, at least 95%, or at least 99% of the time) during which the electrolytic reaction is performed may be less than or equal to 10:1, less than or equal to 7:1, less than or equal to 4:1, less than or equal to 3:1, less than or equal to 2:1, less than or equal to 3:2, less than or equal to 1:1, less than or equal to 2:3, less than or equal to 1:2, less than or equal to 1:4, or less than or equal to 1:7. Combinations of the above-referenced ranges are possible (e.g., greater than or equal to 1:10 and less than or equal to 10:1, or greater than or equal to 1:7 and less than or equal to 4:1). Other ranges are also possible. In some embodiments, the ratio of total mass of alkali metal halide and/or alkaline earth metal halide to total mass of target-metal-containing material (e.g., a transition metal halide or a rare earth metal halide) in the electrolyte at one or more times (e.g., during at least 50%, at least 75%, at least 90%, at least 95%, or at least 99% of the time) during which the electrolytic reaction is performed may be at least 1:20, at least 1:19, at least 1:15, at least 1:10, at least 1:5, at least 1:2, at least 1:1, at least 2:1, at least 4:1, at least 5:1, at least 10:1, at least 15:1, at least 20:1, and/or less than or equal to 20:1, less than or equal to 15:1, less than or equal to 10: 1, less than or equal to 5:1, less than or equal to 4:1, less than or equal to 2:1, less than or equal to 1:1, less than or equal to 1:2, less than or equal to 1:5, less than or equal to 1:10, less than or equal to 1:15, less than or equal to 1:19, or less. Combinations of the above-referenced ranges are possible (e.g., at least 1:20 and less than or equal to 20:1).

In some embodiments, target-metal-containing materials (e.g., a transition metal halide or a rare earth metal halide) may occupy the electrolyte (at any given time) in a volume percentage of greater than or equal to 20 vol% (e.g., greater than or equal to 30 vol%, greater than or equal to 40 vol%, greater than or equal to 50 vol%, greater than or equal to 60 vol%, greater than or equal to 75 vol%, greater than or equal to 88 vol%, greater than or equal to 90 vol%, or greater) and/or less than or equal to 95 vol% (e.g., less than or equal to 90 vol%, less than or equal to 88 vol%, less than or equal to 75 vol%, less than or equal to 60 vol%, less than or equal to 50 vol%, less than or equal to 40 vol%, less than or equal to 30 vol%, or less). Combinations of the above-referenced ranges are possible (e.g., greater than or equal to 20 vol% and less than or equal to 95 vol% , greater than or equal to 30 and less than or equal to 90 vol%, or greater than or equal to 50 vol% and less than or equal to 88 vol%).

In some embodiments, the method comprises electroplating the target metal (e.g., a transition metal or a rare earth metal) within a volume of the electrolyte onto a cathode and/or an anode. As noted above, the target metal within the electrolyte may include any target metal originally present within the electrolyte and/or any target metal introduced to the electrolyte from target-metal-containing materials during operation of the electrolytic cell. In one set of embodiments, the target metal is electroplated onto the cathode. In some embodiments, the electroplated target metal is a solid. For example, referring to FIG. 3, upon an application of an electric potential across anode 104 and cathode 106, the target metal from a volume of electrolyte 108 has been electroplated onto cathode 106 as solid 140.

Any of a variety of appropriate electric potentials may be applied during the electroplating process. For example, in some embodiments, an electric potential of greater than or equal to 0.5 V, greater than or equal to 1 V, greater than or equal to 1.5 V, or more, and/or up to 3.5 V, up to 6V, up to 10 V, or more may be applied across the electrodes. Combinations of the above-referenced ranges are possible (e.g., between 0.5 V and 10 V, between 1 V to 6 V, or between 1.5 V to 3.5 V, etc.).

The electroplating process described above may be carried out for any of a variety of appropriate time durations, such as at least 1 hour, at least 2 hours, at least 3 hours, at least 4 hours, and/or up to 5 hours, up to 6 hours, up to 8 hours, up to 9 hours, or more. Combinations of the above-referenced ranges are possible (e.g., at least 1 hour and up to 9 hours, at least 3 hours and up to 8 hours, at least 4 hours and up to 6 hours, etc.).

The electroplating processes described herein may be operated at any of a variety of appropriate temperatures, such as a temperature of greater than or equal to 120 °C, greater than or equal to 175 °C, greater than or equal to 250 °C, greater than or equal to 300 °C, greater than or equal to 400 °C, greater than or equal to 500 °C, greater than or equal to 550 °C, greater than or equal to 600 °C, greater than or equal to 700 °C, greater than or equal to 800 °C, or more, and/or less than or equal to 900 °C, less than or equal to 800 °C, less than or equal to 700 °C, less than or equal to 600 °C, less than or equal to 550 °C, less than or equal to 500 °C, less than or equal to 400 °C, less than or equal to 300 °C, less than or equal to 250 °C, less than or equal to 175 °C, or less. Depending on the type of target metal, the operating temperature may differ. For example, in some embodiments in which the target metal is a transition metal (e.g., Fe), the electroplating process may be carried out between 120 °C and 600 °C, between 175 °C to 500 °C, or between 250 °C to 450 °C. As another example, in some embodiments in which the target metal is a rare earth metal (e.g., Dy), the electroplating process may be carried out between 300 °C and 900 °C, between 400 °C to 800 °C, or between 550 °C to 700 °C.

In some embodiments, the electrolyte may have any of a variety of measured values of current (e.g., absolute current) during operation of the electrolytic cell. For example, it may be particularly advantageous to maintain a particular level of current passing through the electrolyte, e.g., to allow for efficient electroplating of target metals onto the cathode. In some embodiments, target-metal-containing materials (e.g., in the form halogen salt(s)) may be periodically introduced as desired to maintain a desired current level. For example, in some embodiments, target-metal-containing materials may be introduced such that the measured value of current (e.g., absolute current) is maintained within 30%, within 20%, within 10%, within 5%, within 3%, or less of the initial value of current (e.g., absolute current).

In some embodiments, after electroplating the target metals onto the cathode and/or anode, the electroplated target metal may be removed and harvested from the cathode and/or anode. In some cases, the anode and/or cathode may be first removed (while under an applied electric potential) from the electrolytic cell prior to recovering the electroplated target metal from the removed anode and/or cathode. For example, as shown in FIG. 3, anode 104 and/or cathode 106 may be removed from cell 102 while under an applied electric potential. Electroplated solid target metal 140 on cathode 106 may be then removed from cathode 106 and collected.

In some embodiments, the electrolytic cell may be operated continuously. For example, after harvesting the electroplated target metal from the cathode and/or anode, additional target-metal-containing materials may be fed to the electrolyte for further electroplating. The electrolytic cell may be kept running while harvesting the metal and/or adding additional target-metal-containing materials.

In some embodiments, the method described herein may result in a relatively high amount of electroplated target metal per amp-hour of current. In certain embodiments, greater than 1 gram/amp-hour, greater than 1.5 grams/amp-hour, greater than 2 grams/amp-hour, or more, and/or up to 2 grams/amp-hour, up to 3 grams/amp- hour, or more of target metal may be electroplated onto the cathode and/or anode. In some embodiments, a total amount of greater than 1 gram, greater than 2 grams, greater than 5 grams, greater than 10 grams, greater than 50 grams, or more, and/or up to 100 grams, up to 200 grams, up to 500 grams, up to 1000 grams, up to 2000 grams, or more of target metal may be electroplated per operation.

The electroplated target metal(s) may have a relatively high purity level, in some embodiments. The purity level may be determined by calculating the percentage of electroplated target metal(s) in the total amount of electroplated materials including both the target metal(s) and any impurities (e.g., non-target metal(s)). In some embodiments, a single target metal may be electroplated. In some embodiments, two or more target metals may be electroplated simultaneously. In embodiments in which two or more target metals are electroplated, purity level of the electroplated target metals may be determined by dividing the total amount of the two or more electroplated target metals by the total amount of electroplated materials, including both the two or more target metals and any impurities (e.g., non-target metal(s)). For example, in some embodiments, the electroplated target metal(s) may have a purity of greater than 90%, greater than 95%, greater than 97%, greater than 98%, greater than 99%, and/or up to 99.9%, up to 99.99%, or 100%.

In some embodiments, electroplating of a target transition metal from a transition metal halide is provided. For example, in one set of embodiments, the transition metal is Fe. In some such embodiments, the transition metal halide is FeCh. In some embodiments, an electrolyte comprising a molten salt bath may be employed to electroplate the transition metal. An electrolyte may comprise at least two halogens, such as a chloride and a fluoride, and may comprise at least two metals, e.g., the target transition metal and an alkali and/or alkaline earth metal (e.g., K, Na, Li, and/or Ca). For example, the electrolyte may comprise a combination of alkali metal halide(s) with mixed halogens (e.g., NaCl and/or KC1 combined with NaF and/or KF) and a halide of the target transition metal (e.g., FeCh). The transition metal halide may be present in any of a variety of appropriate amounts in the electrolyte, such as from 30 wt% to 85 wt%, from 40 wt% to 70 wt%, or from 45 wt% to 60 wt%. The alkali metal halide(s) comprising a chloride species (e.g., NaCl and/or KC1) may be present in any of a variety of appropriate amounts in the electrolyte, such as from 10 wt% to 50 wt%, from 15 wt% to 35 wt%, from 20 wt% to 30 wt%, from 5 wt% to 25 wt%, from 10 wt% to 27 wt%, or from 12 wt% to 20 wt%. The alkali metal halide(s) comprising a fluoride species (e.g., NaF and/or KF) may be present in any of a variety of appropriate amounts in the electrolyte, such as from 2 wt% to 17 wt%, from 3 wt% to 14 wt%, from 4 wt% to 8 wt%, from 1 wt% to 19 wt%, from 3 wt% to 15 wt% , or from 4 wt% to 9 wt%.

In some embodiments, electroplating of a rare earth metal (e.g., a heavy rare earth metal) from a rare earth metal halide (e.g., heavy rare earth metal halide) is provided. For example, in one set of embodiments, the rare earth metal is Dy. In some such embodiments, the rare earth metal halide is DyCL. In some embodiments, an electrolyte comprising a molten salt bath may be employed to electroplate the rare earth metal. An electrolyte may comprise at least two halogens, such as a chloride and a fluoride, and may comprise at least two metals, such as the target rare earth metal and an alkali or alkaline earth metal (e.g., K, Li, Na, and/or Ca). For example, the electrolyte may comprise a combination of alkali and/or alkaline earth metal halide(s), such as LiCl and LiF, and a halide of the target rare earth metal, such as DyCh. The rare earth metal halide may be present in any of a variety of appropriate amounts in the electrolyte, such as from 20 wt% to 95 wt%, from 30 wt% to 90 wt%, or from 50 wt% to 88 wt%. The alkali and/or alkaline earth metal halide(s) comprising a chloride species (e.g., LiCl) may be present in any of a variety of appropriate amounts in the electrolyte, such as from 3 wt% to 50 wt%, from 4 wt% to 30 wt%, or from 5 wt% to 20 wt%. The alkali and/or alkaline earth metal halide(s) comprising a fluoride species (e.g., LiF) may be present in any of a variety of appropriate amounts in the electrolyte, such as from 2 wt% to 40 wt%, from 3 wt% to 20 wt%, or from 5 wt% to 15 wt%.

The following examples are intended to illustrate certain embodiments of the present invention, but do not exemplify the full scope of the invention.

EXAMPLE 1

This example describes electroplating dysprosium (target metal) from a rare earth metal chloride (target-metal-containing material).

The electrolytic cell assembly comprised a 99.9% cylindrical graphite crucible (4.5” ID), a smelting furnace (with a capability of 1200 °C or greater temperature control), a cathode rod comprising W, Mo, Nb, or Ta, and an anode rod comprising graphite. Various rare earth metal chlorides (e.g., dysprosium chloride, holmium chloride, terbium chloride) and alkali or alkaline earth metal chlorides (e.g., anhydrous lithium chloride, lithium fluoride, anhydrous calcium chloride, potassium chloride, potassium fluoride, etc.) may be used. For example, within a graphite or 316 stainless steel body (or another crucible with similar corrosion and thermal resistance), a eutectic melt of dysprosium chloride and an alkali metal chloride and fluoride salt (e.g., potassium, lithium, or sodium based) was melted. Operating conditions for forming the melt were within the range of 400 °C to 700 °C, depending on the eutectic used. For example, for a DyCh-LiCl-LiF melt containing 42.5 wt% to 58 wt% DyCF, 32 wt% to 38 wt% LiCl, and balance of LiF, an operating temperature of 625 °C to 700 °C was used.

Once the molten salt eutectic was melted to a completely molten state, a tungsten cathode (1/8”- 1/4”) and high purity graphite anode ( l/4”-3/8”) were inserted vertically in parallel at an even height into the electrolyte. A 2.5” graphite crucible was used to house the cell, and the electrodes were spaced 1.25 inches apart in the center of the cell. Alternatively, the graphite cell housing may also be used as an anode with the tungsten rod down the direct center, thereby transforming the electrode configuration from a parallel configuration to a concentric configuration.

The cell was operated an inert atmosphere (e.g., using argon, nitrogen, or helium). An inert glovebox environment may be used for electroplating target metal on 10g scale.

Once electrodes were properly spaced, and molten electrolyte was melted, and a potential of 2.6-3.2V was applied to drive current through the cell. At peak efficiency, the cell produced 2.5g Dy metal per amp-hour passed. After harvesting the electroplated Dy metal at the cathode, target-containing-material DyCIs was fed to the cell to achieve a mass percentage of 42.5 %-58% DyCh once again for additional electroplating. The amount of DyCh in the electrolyte was kept above 20 wt% at during operation to maintain efficient electroplating of Dy. To maintain continuous cell operation, Dy metal was harvested and DyCh was fed to the electrolyte about every 4 hours.

EXAMPLE 2

This example describes electroplating iron (target metal) from a molten salt (target-metal-containing material) .

A molten salt with the composition of 26.4 wt% NaCl, 12.87 wt% KC1, 57.11 wt% FeCF, 1.17 wt% NaF, and 2.44 wt% KF was heated to 350 °C. An 1/8” copper cathode and 1/4” graphite anode were inserted into the system. A voltage of 1.8 volts was applied to the system for 2 hours. Upon completion of the voltage application and cooling, approximately 5 grams of iron dendrites and flake were present on the cathode.

EXAMPLE 3 This example describes electroplating neodymium (target metal) from a molten salt (target-metal-containing material).

A molten salt with the composition of 32 wt% LiCl, 50 wt% NdCh, and 18 wt% LiF was heated to 800 °C. A 1/4” iron cathode and 1/4” graphite anode were inserted into the system. A voltage of 4.7 V was applied to the system for 2.5 hours. Upon completion of the voltage application and cooling, approximately 5 grams of neodymium dendrites and flake were present on the cathode.

While several embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, and/or methods, if such features, systems, articles, materials, and/or methods are not mutually inconsistent, is included within the scope of the present invention.

The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein 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. 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 unless clearly indicated to the contrary. 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 without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

As used herein 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 herein 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.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

Some embodiments may be embodied as a method, of which various examples have been described. The acts performed as part of the methods may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include different (e.g., more or less) acts than those that are described, and/or that may involve performing some acts simultaneously, even though the acts are shown as being performed sequentially in the embodiments specifically described above.

Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of’ and “consisting essentially of’ shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

Claims

1. A method, comprising: within an electrolytic cell comprising a cathode, an anode, and an electrolyte having a volume, electroplating a target metal within the volume of the electrolyte onto the cathode and/or the anode; wherein the electrolyte comprises at least two halogens.

2. The method of claim 1, wherein the target metal comprises a rare earth metal and/or a transition metal.

3. The method of claim 2, wherein the rare earth metal comprises a heavy earth metal and/or a light rare earth metal.

4. The method of any one of claims 1-3, further comprising exposing a target-metal containing material to the volume of the electrolyte, wherein the target-metal containing material comprises a rare earth metal halide and/or a transition metal halide.

5. The method of any one of claims 1-4, wherein electroplating the target metal comprises electroplating the target metal onto the cathode.

6. The method of any one of claims 1-5, wherein the at least two halogens comprise a chloride and a fluoride.

7. The method of any one of claims 1-6, where the electrolyte is a molten salt.

8. The method of any one of claims 1-7, wherein the electrolyte comprises at least two halides comprising a halide of the target metal and at least one selected from the group of an alkali metal halide and an alkaline earth metal halide.

9. The method of claim 8, wherein a ratio of mass of the alkali and/or alkaline earth metal halide to mass of the halide of the target metal is between 1:20 to 20:1.

10. The method of any one of claims 1-9, wherein the electroplating is carried out at a temperature of greater than or equal to 120 °C and less than or equal to 900 °C.

11. The method of any one of claims 1-10, wherein the electroplated target metal has a purity of greater than 90%.

12. The method of any one of claims 1-11, wherein the electroplated target metal is in a solid state.

13. The method of any one of claims 1-12, wherein the target metal is electroplated in an amount of greater than 1 gram.

14. The method of any one of claims 1-13, wherein the electrolyte comprises the target metal and at least one metal selected from an alkali metal and/or alkaline earth metal.

15. An electrolytic cell, comprising: a cathode; an anode; and an electrolyte comprising at least two halogens; wherein the electrolytic cell is configured to electroplate, on the cathode and/or the anode, a target metal from a volume of the electrolyte.

16. The electrolytic cell of claim 15, wherein the cathode comprises a cathode comprising a refractory metal.

17. The electrolytic cell of any one of claims 15-16, wherein the target metal comprises a rare earth metal and/or a transition metal.

18. The electrolytic cell of any one of claims 15-17, wherein the target-metal containing material comprises a rare earth metal halide and/or a transition metal halide.

19. The electrolytic cell of any one of claims 15-18, wherein the at least two halogens comprise a chloride and a fluoride.

20. The electrolytic cell of any one of claims 15-19, wherein the electrolyte is a molten salt.

21. The electrolytic cell of any one of claims 15-20, wherein the electrolyte comprises at least two halides comprising a halide of the target metal and at least one selected from the group of an alkali metal halide and an alkaline earth metal halide.

22. The electrolytic cell of claim 21, wherein a ratio of mass of alkali and/or alkaline earth metal halide to mass of the halide of the target metal is between 1:20 to 20:1.

23. The electrolytic cell of any one of claims 15-22, wherein the electrolyte comprises the target metal and at least one metal selected from an alkali metal and/or alkaline earth metal.