Electrolytic production and purification of graphite

Abstract

Processes for removing carbonaceous material from an electrode and from alkali metal / alkaline earth metal oxide by-products that are co-deposited on the electrode are disclosed. The electrode is contacted with a molten bath containing a mixture of an alkali metal / alkaline earth metal carbonate with the alkali metal / alkaline earth metal oxide, and thereafter the alkali metal / alkaline earth metal oxide is removed as a liquid from the electrode and dissolved into the molten bath, and the carbonaceous material is recovered as a solid product from the electrode and dispersed into the molten bath. Subsequently, the isolated carbonaceous material is removed from the molten bath, and then carbon dioxide is introduced into the molten bath to convert the alkali metal / alkaline earth metal oxide back to the alkali metal / alkaline earth metal carbonate.

Description

ELECTROLYTIC PRODUCTION AND PURIFICATION OF GRAPHITEREFERENCE TO RELATED APPLICATION

[0001] This application is being filed on June 16, 2025, as a PCT International Patent Application and claims the benefit of and priority to U.S Patent Application No. 63 / 661,092. filed on June 18. 2024. the disclosure of which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure generally relates to the electrolytic production and purification of carbonaceous materials, and more particularly, relates to processes of removing carbonaceous materials from an electrode and from oxide by-products that are codeposited on the electrode, with improved efficiency.BACKGROUND

[0003] Carbonaceous materials can be produced through the electrochemical reduction of carbon-containing reactants on an electrode in an electrochemical cell. However, traditional methods of separating the carbonaceous materials from the electrode and from oxide by-products that are co-deposited on the electrode are time consuming and highly energy inefficient. Thus, it would be beneficial to develop new methods for the removal and purification of the solid carbonaceous materials. Accordingly, it is to these ends that the present invention is generally directed.SUMMARY

[0004] This summary is provided to introduce a selection of concepts in a simplified form that are further described herein. This summary' is not intended to identify required or essential features of the claimed subject matter. Nor is this summary intended to be used to limit the scope of the claimed subject matter.

[0005] Disclosed herein are processes for removing carbonaceous material from an electrode and from oxide by-products that are co-deposited on the electrode. Such processes can comprise (i) contacting an electrode that is at least partially covered with a carbonaceous material and an alkali metal oxide and / or an alkaline earth metal oxide with a molten bath, the molten bath comprising a mixture of an alkali metal carbonate and / or an alkaline earthmetal carbonate with the alkali metal oxide and / or the alkaline earth metal oxide. All or a portion of the alkali metal oxide and / or the alkaline earth metal oxide is removed as a liquid from the electrode and dissolved into the molten bath, and a portion of the carbonaceous material is removed as a solid from the electrode and dispersed into the molten bath. These processes then can comprise (ii) removing all or a portion of the carbonaceous material from the molten bath, and (hi) introducing CO2 into the molten bath to convert all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide to the alkali metal carbonate and / or an alkaline earth metal carbonate.

[0006] Additionally, the processes disclosed herein can comprise, prior to step (i), a step of reducing the alkali metal carbonate and / or the alkaline earth metal carbonate in an electrochemical cell to the carbonaceous material and the alkali metal oxide and / or the alkaline earth metal oxide. Advantageously, the alkali metal carbonate and / or the alkaline earth metal carbonate produced in step (iii) can optionally be recycled to the electrochemical cell, making the disclosed processes cyclic or circular. Therefore, in circumstances where a step of reducing the alkali metal carbonate and / or the alkaline earth metal carbonate in the electrochemical cell is performed prior to step (i), the processes disclosed herein can further comprise, after step (iii), a step of recycling the alkali metal carbonate and / or the alkaline earth metal carbonate to the electrochemical cell.

[0007] Both the foregoing summary and the following detailed description provide examples and are explanatory only. Accordingly, the foregoing summary and the following detailed description should not be considered to be restrictive. Further, features or variations can be provided in addition to those set forth herein. For example, certain aspects can be directed to various feature combinations and sub-combinations described in the detailed description.BRIEF DESCRIPTION OF THE FIGURES

[0008] The following figures form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to the figures in combination with the detailed description.

[0009] FIG. 1 illustrates a representative schematic flow diagram of a process to remove carbonaceous materials from an electrode and from oxide by-products that are codeposited on the electrode.

[0010] FIG. 2 presents an overlay plot of the thermogravimetric analysis (TGA) curve and the corresponding mass-spectrometry ion current signal for carbon dioxide from Example 1.

[0011] FIG. 3 presents a plot of the thermogravimetric analysis (TGA) curve for lithium oxide (Li2O) from Example 2.

[0012] FIG. 4 presents a phase diagram showing the operating temperature and composition window for molten mixtures of lithium carbonate (Li2CCh) and lithium oxide (Li2O) from Example 3.

[0013] FIG. 5 depicts a transmission electron microscopy (TEM) image of the carbonaceous material recovered from Example 4.

[0014] FIG. 6 depicts a second transmission electron microscopy (TEM) image of the carbonaceous material recovered from Example 4.

[0015] While the inventions disclosed herein are susceptible to various modifications and alternative forms, only a few specific aspects have been shown by way of example in the drawings and described in detail below. The figures and detailed descriptions of these specific aspects are not intended to limit the breadth or scope of the inventive concepts or the appended claims in any manner. Rather, the figures and detailed descriptions are provided to illustrate the inventive concepts to a person of ordinary skill in the art and to enable such person to make and use the inventive concepts.DEFINITIONS

[0016] To define more clearly the terms used herein, the following definitions are provided. Unless otherwise indicated, the following definitions are applicable to this disclosure. If a term is used in this disclosure but is not specifically defined herein, the definition from the IUPAC Compendium of Chemical Terminology, 2nd Ed (1997), can be applied, as long as that definition does not conflict with any other disclosure or definition applied herein, or render indefinite or non-enabled any claim to which that definition is applied. To the extent that any definition or usage provided by any document incorporated herein by reference conflicts with the definition or usage provided herein, the definition or usage provided herein controls.

[0017] Herein, features of the subject matter are described such that, within particular aspects, a combination of different features can be envisioned. For each and every aspect and each and every feature disclosed herein, all combinations that do not detrimentally affect thesystems, processes, or methods described herein are contemplated with or without explicit description of the particular combination. Additionally, unless explicitly recited otherwise, any aspect or feature disclosed herein can be combined to describe inventive systems, processes, or methods consistent with the present disclosure.

[0018] In this disclosure, while systems and processes are described in terms of “comprising’7various components or steps, the systems and processes also can “consist essentially of’ or “consist of’ the various components or steps, unless stated otherwise.

[0019] The terms “a,” “an,” and “the” are intended to include plural alternatives, e.g., at least one, unless otherwise specified. For instance, the disclosure of “a carbonaceous material” is meant to encompass one carbonaceous material, or mixtures or combinations of more than one carbonaceous material, unless otherwise specified.

[0020] The term “contacting” is used herein to describe processes / methods in which the materials are contacted together in any order, in any manner, and for any length of time, unless otherwise specified. For example, the materials can be mixed, dipped, dissolved, reacted, or otherwise contacted in some other manner or by any suitable method or technique.

[0021] Generally, groups of elements are indicated using the numbering scheme indicated in the version of the periodic table of elements published in Chemical and Engineering News, 63(5), 27, 1985. In some instances, a group of elements can be indicated using a common name assigned to the group; for example, alkali metals for Group 1 elements and alkaline earth metals for Group 2 elements.

[0022] The term “carbonaceous material” as used herein refers to substances that primarily consist of carbon atoms, for example, at least 95 wt. %, at least 98 wt %, or substantially 100% carbon. By itself, the term “carbonaceous material” does not exclude the presence of elements other than carbon unless explicitly indicated.

[0023] Several types of ranges are disclosed in the present invention. When a range of any ty pe is disclosed or claimed, the intent is to disclose or claim individually each possible number that such a range could reasonably encompass, including end points of the range as well as any sub-ranges and combinations of sub-ranges encompassed therein. For example, the temperature in the molten bath can be in various ranges. By a disclosure that the temperature of the mixture in the molten bath can range from 1000 °C to 2000 °C, the intent is to recite that the temperature can be any temperature within the range and, for example, can include any range or combination of ranges from 1000 °C to 2000 °C, such as from 1300 °C to 1800 °C, from 1350 °C to 1750 °C, from 1400 °C to 1700 °C, and so forth.Likewise, all other ranges disclosed herein should be interpreted in a manner similar to this example.

[0024] In general, an amount, size, formulation, parameter, range, or other quantity or characteristic is “about” or “approximate” whether or not expressly stated to be such. Whether or not modified by the term “about” or “approximately,” the claims include equivalents to the quantities or characteristics.

[0025] Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the ty pical methods, devices, and materials are herein described.

[0026] All publications and patents mentioned herein are incorporated herein by reference in their entirety for the purpose of describing and disclosing, for example, the constructs and methodologies that are described in the publications and patents, which might be used in connection with the presently described invention.DETAILED DESCRIPTION

[0027] Disclosed herein are methods for removing carbonaceous materials from an electrode and from oxide by-products that are co-deposited on the electrode. Traditional methods of removing carbonaceous materials from an electrode and from oxide by-products that are co-deposited on the electrode are time consuming and highly energy inefficient. However, by utilizing the processes disclosed herein, energy consumption can be significantly reduced and less steps are needed to separate and isolate the carbonaceous material from the electrode and from oxide by-products that are co-deposited on the electrode.PROCESSES FOR REMOVING CARBONACEOUS MATERIAL

[0028] Disclosed herein are processes for removing carbonaceous material from an electrode and from oxide by-products that are co-deposited on the electrode. One such process can comprise (i) contacting an electrode that is at least partially covered with a carbonaceous material and an alkali metal oxide and / or an alkaline earth metal oxide with a molten bath, which comprises a mixture of an alkali metal carbonate and / or an alkaline earth metal carbonate with the alkali metal oxide and / or the alkaline earth metal oxide, in which all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide is removed as a liquid from the electrode and dissolved into the molten bath, and a portion of thecarbonaceous material is removed as a solid from the electrode and dispersed into the molten bath, (ii) removing all or a portion of the carbonaceous material from the molten bath, and (iii) introducing CO2 into the molten bath to convert all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide to the alkali metal carbonate and / or the alkaline earth metal carbonate. Optionally, prior to step (i), the disclosed processes can further comprise a step of reducing the alkali metal carbonate and / or the alkaline earth metal carbonate in an electrochemical cell to the carbonaceous material and the alkali metal oxide and / or the alkaline earth metal oxide. Also optionally, the alkali metal carbonate and / or the alkaline earth metal carbonate produced in step (iii) can be recycled to the electrochemical cell, making the disclosed processes cyclic or circular. Therefore, in circumstances where a step of reducing the alkali metal carbonate and / or the alkaline earth metal carbonate in an electrochemical cell is performed prior to step (i), the processes disclosed herein can further comprise, after step (iii), a step of recycling the alkali metal carbonate and / or the alkaline earth metal carbonate to the electrochemical cell.

[0029] Generally, the features of the processes (e.g., the electrode, the carbonaceous material, the alkali metal oxide and / or the alkaline earth metal oxide, the alkali metal carbonate and / or the alkaline earth metal carbonate, the molten bath, and the conditions under which each of the steps are conducted, among others) are independently described herein and these features can be combined in any combination to further describe the disclosed processes. Moreover, additional process steps can be performed before, during, and / or after any of the steps in the processes disclosed herein, and can be utilized without limitation and in any combination to further describe these processes, unless stated otherwise. Further, any carbonaceous products removed in accordance with the disclosed processes are within the scope of this disclosure and are encompassed herein.

[0030] In step (i), an electrode, which is at least partially covered with a carbonaceous material and an alkali metal oxide and / or an alkaline earth metal oxide, is contacted with a molten bath. The source of the electrode is not particular limited, and the relative amount of the surface area of the electrode that is covered (e.g., partially covered) is likewise not limited. For example, the electrode can originate from an electrochemical cell, which can include, but is not limited to, molten salt electrolyzers, galvanic cells, voltaic cells, electrolytic cells, fuel cells, concentration cells, photoelectrochemical cells, chargeable and non-rechargeable cells, and the like. In circumstances where a step of reducing the alkali metal carbonate and / or the alkaline earth metal carbonate in an electrochemical cell isperformed prior to step (i). the electrode in step (i) can originate from this electrochemical cell.

[0031] Consistent with aspects of this invention, the electrode in step (i) can be a cathode (or a negative terminal). The cathode is constructed from materials which resist degradation at high temperatures and at the electrochemical conditions under which it is subjected. Representative materials for constructing the cathode can include, but are not limited to, titanium, stainless steel, graphite, metal super alloys comprising two or more of Ni, Cr, Fe, and / or Mo, and the like, and this includes combinations of two or more of these materials in any suitable relative amount. For instance, the cathode can have a core-shell construction in which the core is one material and the shell is a different material. As another example, the cathode can have atop and a bottom portion in which the top portion is one material and the bottom portion is a different material.

[0032] Carbonaceous materials refer to substances that primarily comprise carbon. Generally, carbonaceous materials can be produced through the electrochemical reduction or oxidation of carbon-containing reactants at the interface of an electrode. Beneficially, the carbonaceous materials produced can be employed in various industries and fields. For instance, carbonaceous materials can exhibit diverse characteristics and properties including, but not limited to, high graphitization factor, high electrical and thermal conductivity, thermal stability, and mechanical strength, making them valuable in various end-use applications. Additionally, it is believed that sustainably converting carbon-containing reactants such as alkali metal carbonates and alkaline earth metal carbonates, methane (CFU), and carbon dioxide (CO2), to useful carbonaceous materials is highly advantageous not only from an environmental perspective, but also from an energy -footprint standpoint.

[0033] Referring back to step (i), the carbonaceous material is typically present as a solid and may be coated or adhered onto the electrode. The carbonaceous material can primarily comprise elemental carbon, non-limiting examples of which can include graphites, graphitizable materials, nongraphitizable materials, graphenes, carbon blacks, amorphous carbons, activated carbons, carbon nanotubes, carbon (nano)fibers, fullerenes, and the like, as well as any combination thereof. In certain aspects, the carbonaceous material comprises graphite (with vary ing degrees of suitable graphitization), a graphitizable material (which is convertible to graphite in a furnace, for instance, a material with a graphitization level below 90% that is converted to a graphite material with a graphitization level over 90%), or any combination thereof. The carbonaceous material can also comprise any element other thancarbon, in any suitable minor amount. For example, the carbonaceous material can comprise elemental carbon and additionally hydrogen, oxygen, and / or various metal elements, and the like, as well as mixtures thereof. As one of ordinary skill in the art would recognize, in circumstances where a step of reducing the alkali metal carbonate and / or the alkaline earth metal carbonate in an electrochemical cell is performed prior to step (i), the composition of the carbonaceous material on the electrode can depend on the composition of the alkali metal carbonate and / or the alkaline earth metal carbonate, generally present as an electrolyte, in the electrochemical cell.

[0034] In step (i) of the processes disclosed herein, any suitable alkali metal oxide and / or an alkaline earth metal oxide can be present on the electrode. Generally, the alkali metal oxide can comprise oxygen and an element selected from Group 1 of the periodic table. Illustrative examples of alkali metal oxide compounds that can be present on the electrode can include, but are not limited to, Li2O, Na2O, K2O. Rb2O, CS2O, and the like, including combinations thereof. Likewise, the alkaline earth metal oxide can comprise oxygen and an element selected from Group 2 of the periodic table. Illustrative examples of alkaline earth metal oxide compounds that can be present on the electrode can include, but are not limited to, BeO, MgO, CaO, SrO, BaO, and the like, including combinations thereof. As one of ordinary skill in the art would recognize, in circumstances where a step of reducing the alkali metal carbonate and / or the alkaline earth metal carbonate in an electrochemical cell is performed prior to step (i), the composition of the alkali metal oxide and / or the alkaline earth metal oxide on the electrode can be dependent on the composition of the alkali metal carbonate and / or the alkaline earth metal carbonate, generally present as an electrolyte, in the electrochemical cell.

[0035] The relative amounts of carbonaceous material and alkali metal oxide and / or alkaline earth metal oxide present on the electrode in step (i) is not particularly limited. Generally, the carbonaceous material and the alkali metal oxide and / or the alkaline earth metal oxide can be present on the electrode in any suitable amount, for example, from 0 to 30 mol % of the alkali metal oxide (or the alkaline earth metal oxide), or from 2 to 25 mol % of the alkali metal oxide (or the alkaline earth metal oxide). As one of ordinary skill in the art would recognize, in circumstances where a step of reducing the alkali metal carbonate and / or the alkaline earth metal carbonate in an electrochemical cell is performed prior to step (i), the respective amounts of carbonaceous material and alkali metal oxide and / or alkaline earth metal oxide present on the electrode can be dependent on certain reaction conditions such astemperature, electrolytic current, time, and the amount of alkali metal carbonate and / or the alkaline earth metal carbonate, generally present as an electrolyte, in the electrochemical cell. Further, in addition to the carbonaceous material and alkali metal oxide and / or alkaline earth metal oxide present on the electrode in step (i), other materials also can be present, often in minor amounts, such as an alkaline metal carbonate and / or alkaline earth metal carbonate.

[0036] In step (i), the electrode is contacted with a molten bath which comprises a mixture of an alkali metal carbonate and / or an alkaline earth metal carbonate and the alkali metal oxide and / or the alkaline earth metal oxide. Thus, the alkali metal oxide and / or the alkaline earth metal oxide present in the molten bath is the same alkali metal oxide and / or alkaline earth metal oxide present on the electrode. As a non-limiting example, when lithium oxide (Li2O) is present on the electrode in step (i), lithium oxide (Li2O) should be present in the molten bath as well. Any suitable alkali metal oxide and / or an alkaline earth metal oxide can be present in the molten bath, including combinations of two more of these oxide compounds.

[0037] Likewise, any suitable alkali metal carbonate and / or an alkaline earth metal carbonate can be present in the molten bath. Generally, the alkali metal carbonate can comprise a carbonate anion (CO32) and an element selected from Group 1 of the periodic table. Illustrative examples of alkali metal carbonate compounds that can be present in the molten bath can include, but are not limited to, Li2CO3. Na2COs, K2CO3. Rb2CO3, CS2CO3, and the like, including combinations or mixtures thereof in varying proportions. Likewise, the alkaline earth metal carbonate can comprise a carbonate anion and an element selected from Group 2 of the periodic table. Illustrative examples of alkaline earth metal carbonate compounds that can be present in the molten bath can include, but are not limited to, BeCOs, MgCCh, CaCCh, SrCCh, BaCCh, and the like, including combinations or mixtures thereof in varying proportions.

[0038] Typically, in the disclosed processes, the alkali metal element in both the alkali metal oxide and the alkali metal carbonate is the same. For example, in an aspect, the alkali metal oxide comprises Li2O and the alkali metal carbonate comprises L12CO3. In accordance with another aspect, the alkali metal oxide comprises Na2O and the alkali metal carbonate comprises Na2CC>3. In accordance with yet another aspect, the alkali metal oxide comprises K2O and the alkali metal carbonate comprises K2CO3.

[0039] Likewise, in the processes disclosed herein, the alkaline earth metal element in both the alkaline earth metal oxide and the alkaline earth metal carbonate is generally thesame. For example, in an aspect, the alkaline earth metal oxide comprises MgO and the alkaline earth metal carbonate comprises MgCCh. In accordance with another aspect, the alkaline earth metal oxide comprises CaO and the alkaline earth metal carbonate comprises CaCCh. In accordance with yet another aspect, the alkaline earth metal oxide comprises SrO and the alkaline earth metal carbonate comprises SrCOs. In accordance with still another aspect, the alkaline earth metal oxide comprises BaO and the alkaline earth metal carbonate comprises BaCCh

[0040] The relative amounts of the alkali metal oxide and / or the alkaline earth metal oxide present in the molten bath is not particularly limited. While not limited thereto, the amount of alkali metal oxide and / or the alkaline earth metal oxide present in the molten bath mixture can fall within a range from 0 to 30 mol %, based on the total moles of the alkali metal carbonate and / or an alkaline earth metal carbonate and the alkali metal oxide and / or the alkaline earth metal oxide components in the molten bath. In an aspect, the minimum amount of alkali metal oxide and / or the alkaline earth metal oxide present in the molten bath mixture can be 0. 2. 5, 8. 10, or 12 mol %. In another aspect, the maximum amount of alkali metal oxide and / or the alkaline earth metal oxide present in the molten bath mixture can be 30, 28, 25, 20, 18, or 15 mol %. Generally, the amount of alkali metal oxide and / or the alkaline earth metal oxide present in the molten bath mixture can range from any minimum amount of alkali metal oxide and / or the alkaline earth metal oxide present in the molten bath mixture to any maximum amount of alkali metal oxide and / or the alkaline earth metal oxide present in the molten bath mixture described herein. For instance, the amount of alkali metal oxide and / or the alkaline earth metal oxide present in the molten bath mixture (e.g.. the amount of Li2O in the molten bath) - based on the total moles of alkali metal carbonate and / or an alkaline earth metal carbonate and alkali metal oxide and / or the alkaline earth metal oxide components in the molten bath - can be in a range from 2 to 28 mol %, from 5 to 25 mol %, from 8 to 20 mol %, from 10 to 18 mol %, or from 12 to 15 mol %. As one of ordinary skill in the art would recognize, the amount of alkali metal oxide and / or the alkaline earth metal oxide present in the molten bath can be dependent on the amount of alkali metal carbonate and / or the alkaline earth metal carbonate present in the molten bath.

[0041] Likew ise, the relative amounts of the alkali metal carbonate and / or the alkaline earth metal carbonate present in the molten bath is not particularly limited. While not limited thereto, the amount of alkali metal carbonate and / or the alkaline earth metal carbonate present in the molten bath mixture can fall within a range from 0 to 99 mol %, based on the totalmoles of the alkali metal carbonate and / or an alkaline earth metal carbonate and the alkali metal oxide and / or the alkaline earth metal oxide components in the molten bath. In an aspect, the minimum amount of alkali metal carbonate and / or the alkaline earth metal carbonate present in the molten bath mixture can be 0, 20, 50, 70, 80, or 85 mol %. In another aspect, the maximum amount of alkali metal carbonate and / or the alkaline earth metal carbonate present in the molten bath mixture can be 99. 97. 95, 93, 92, or 90 mol %. Generally, the amount of alkali metal carbonate and / or the alkaline earth metal carbonate present in the molten bath mixture can range from any minimum amount of alkali metal carbonate and / or the alkaline earth metal carbonate present in the molten bath mixture to any maximum amount of alkali metal carbonate and / or the alkaline earth metal carbonate present in the molten bath mixture described herein. For instance, the amount of alkali metal carbonate and / or the alkaline earth metal carbonate present in the molten bath mixture (e.g., the amount of Li2COs in the molten bath) - based on the total moles of the alkali metal carbonate and / or an alkaline earth metal carbonate and the alkali metal oxide and / or the alkaline earth metal oxide components in the molten bath - can be in a range from 20 to 97 mol %, from 50 to 95 mol %, from 70 to 93 mol %, from 80 to 92 mol %, or from 85 to 90 mol %. As one of ordinary skill in the art would recognize, the amount of alkali metal carbonate and / or the alkaline earth metal carbonate present in the molten bath can be dependent on the amount of the alkali metal oxide and / or the alkaline earth metal oxide present in the molten bath.

[0042] The temperature of the molten bath or the mixture in the molten bath is not limited to a particular range. Generally, the temperature of the molten bath or the mixture in the molten bath is any temperature sufficient to remove (via melting and / or dissolution) all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide, as a liquid, from the electrode. For instance, the temperature of the mixture comprising the alkali metal carbonate and / or the alkaline earth metal carbonate and the alkali metal oxide and / or the alkaline earth metal oxide in the molten bath in step (i) can be equal to or slightly greater than the eutectic temperature of the mixture. The eutectic temperature refers to the minimum temperature at which the components of the molten bath melt to form a single, homogenous liquid phase. In one aspect, the temperature of the mixture comprising the alkali metal carbonate and / or the alkaline earth metal carbonate and the alkali metal oxide and / or the alkaline earth metal oxide in the molten bath can be greater than the melting point of the alkali metal carbonate and / or the alkaline earth metal carbonate, but less than the melting point of the alkali metal oxideand / or alkali earth metal oxide. In some aspects, the temperature of the mixture comprising the alkali metal carbonate and / or the alkaline earth metal carbonate and the alkali metal oxide and / or the alkaline earth metal oxide in the molten bath can be greater than the melting points of all of the respective components present in the mixture. In other aspects, the temperature of the mixture comprising the alkali metal carbonate and / or the alkaline earth metal carbonate and the alkali metal oxide and / or the alkaline earth metal oxide in the molten bath can be less than the melting points of all of the respective components present in the mixture. Additionally, the temperature of the mixture in the molten bath can be less than the melting point of the carbonaceous material present on the electrode. This means the temperature at which the carbonaceous material degrades, sublimes, or oxidizes, and this ensures that the carbonaceous material is removed as a solid, and not as a liquid, from the molten bath.

[0043] Often, the temperature of the molten bath or the mixture in the molten bath is at a minimum temperature of 500 °C, 550 °C, 600 °C, 650 °C, or 675 °C; additionally or alternatively, at a maximum temperature of 1600 °C, 1300 °C, 1100 °C, 950 °C, or 725 °C. Generally, the temperature of the molten bath or the mixture in the molten bath can be in a range from any minimum temperature disclosed herein to any maximum temperature disclosed herein. Accordingly, suitable non-limiting ranges can include the following: from 500 to 1600, from 550 to 1300, from 600 to 1100, from 650 to 950, from 675 to 950, or from 675 to 725 °C. In view of the disclosed aspects of the present invention, one of ordinary skill in the art would recognize that the temperature of the mixture in the molten bath can be dependent on the specific alkali metal carbonate and / or alkaline earth metal carbonate present in the molten bath, the specific alkali metal oxide and / or alkaline earth metal oxide present in the molten bath, the specific alkali metal oxide and / or alkaline earth metal oxide present on the electrode, and the specific carbonaceous material present on the electrode, among other factors.

[0044] In a particular aspect, when lithium carbonate (Li2CO3) and lithium oxide (Li2O) are present in the molten bath, the relative molar amounts of Li2O and Li2COs in the molten bath mixture may be selected to form or approximate a eutectic composition. A eutectic composition is characterized by a specific ratio of components at which the mixture exhibits the lowest possible melting temperature, enabling both components to melt simultaneously to form a homogenous liquid phase. Typically, the eutectic point for the molten bath mixture comprising Li2O and L12CO3 occurs when the mixture comprises from 12 to 15 mol % Li2O (based on the total moles of these components in the molten bath) andoperates at a temperature range from 675 to 725 °C. At this composition and temperature, the mixture in the molten bath becomes fully molten, with both Li2O and L12CO - melting simultaneously to form a single homogenous liquid phase. Advantageously, operating the molten bath at or near the eutectic composition may help avoid undesirable decomposition of lithium carbonate at elevated temperatures and support greater energy efficiency. Thus, eutectic or near-eutectic mixtures may be particularly beneficial in the processes disclosed herein.

[0045] Any suitable vessel or crucible can be used to contain the molten bath mixture. Generally, the vessel or crucible should be able to withstand the high temperatures and chemical properties of the mixture in the molten bath. For instance, the vessel or crucible can be constructed from materials including, but not limited to, ceramics, stainless steel, platinum, graphite, porcelain, any specialized materials designed for molten bath applications, and the like, as well as combinations thereof.

[0046] In step (i), the electrode can be contacted with the mixture in the molten bath using any suitable technique. Typically, the electrode can be dipped into the molten bath mixture, which is contained in any suitable vessel or crucible. Other techniques for contacting the electrode with the mixture in the molten bath include, but are not limited to, immersing or submerging the electrode, partial dipping the electrode, continuously dipping the electrode, vertically dipping the electrode, rotationally dipping the electrode, and the like, including combinations thereof.

[0047] The electrode can be contacted with the mixture in the molten bath for any suitable period of time. In general, the electrode can be contacted for a period of time sufficient for all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide to separate from the electrode, as a liquid, and deposit into the molten bath. Additionally or alternatively, the electrode can be contacted with the molten bath mixture for a time period sufficient for a portion of the carbonaceous material to separate from the electrode, as a solid, and deposit into the molten bath. It should be noted that some solid carbonaceous material (e.g.. graphite) may remain on the electrode. Illustrative time periods include, but are not limited to, from 10 min to 10 hr, from 15 min to 5 hr, from 30 min to 10 hr, or from 1 hr to 6 hr.

[0048] Referring now to step (ii) of the processes disclosed herein, all or a portion of the carbonaceous material is removed from the molten bath. All or a portion of the carbonaceous material can be removed or separated from the molten bath by any suitabletechnique known to those of skill in the art or by any suitable technique disclosed herein. Illustrative techniques for the removal or separation of the carbonaceous material include, but are not limited to, extracting, decanting, floatation, pressing, settling (e.g., density differences), centrifuging, filtering, draining, and the like, or any combination of two or more of these techniques. In one aspect, for example, floatation can be used, while in another aspect, decanting can be used.

[0049] The temperature in step (ii) can be any suitable temperature to remove all or a portion of the carbonaceous material from the molten bath. As one of ordinary skill in the art would recognize, the temperature suitable for step (ii) of the processes disclosed herein can be dependent on the technique or combination of techniques utilized to remove or separate the carbonaceous material from the molten bath. In an aspect, the temperature in step (ii) is substantially the same (+ / - 100 °C) as the temperature of the mixture in the molten bath in step (i). For instance, the temperature in step (ii) can be within 75 °C, within 50 °C, within 25 °C, or within 10 °C, of the temperature of the mixture in step (i).

[0050] Referring now to step (iii) of the process, CO2 can be introduced into the molten bath to convert all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide to the alkali metal carbonate and / or the alkaline earth metal carbonate. The CO2 can be introduced into the molten bath by any suitable technique known to those of skill in the art or by any suitable technique disclosed herein. Illustrative techniques for introducing the CO2 into the molten bath include, but are not limited to, sparging, direct injection, gas diffusion, and the like, including combinations thereof. In an aspect, the CO2 gas is superheated in step (in).

[0051] The amount of CO2 introduced into the molten bath can be any suitable amount of CO2 necessary to convert all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide to the alkali metal carbonate and / or the alkaline earth metal carbonate. Likewise, the temperature in step (iii) can be any suitable temperature to convert all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide to the alkali metal carbonate and / or the alkaline earth metal carbonate. In an aspect, the temperature in step (iii) is substantially the same (+ / - 100 °C) as the temperature of the mixture in the molten bath in step (i). For instance, the temperature in step (iii) can be within 75 °C, within 50 °C, within 25 °C, or within 10 °C, of the temperature of the mixture in step (i). Advantageously, when the temperature utilized in step (iii) is substantially the same as the temperature of themixture in the molten bath in step (i), the carbonation reaction of the alkali metal oxide and / or the alkaline earth metal oxide can be completed in a relatively short amount of time.

[0052] Consistent with aspects of the disclosure, the processes can further comprise a step of reducing an alkali metal carbonate and / or an alkaline earth metal carbonate in an electrochemical cell to the carbonaceous material and the alkali metal oxide and / or the alkaline earth metal oxide prior to step (i). The reduction of the alkali metal carbonate and / or the alkaline earth metal carbonate to the carbonaceous material and the alkali metal oxide and / or the alkaline earth metal oxide can occur at the interface of an electrode (e.g., the cathode or the negative electrode) in the electrochemical cell. The entire length of the electrode can be positioned within the electrochemical cell (and the electrolyte), or any suitable portion of the electrode can be positioned within the electrochemical cell (and the electrolyte).

[0053] The electrochemical cell can be operated at any suitable temperature necessary7to reduce the alkali metal carbonate and / or the alkaline earth metal carbonate to the carbonaceous material and the alkali metal oxide and / or the alkaline earth metal oxide. For example, the operating temperature of the electrochemical cell can be equal to or slightly greater than the eutectic temperature of mixture of the alkali metal carbonate and / or the alkaline earth metal carbonate and the alkali metal oxide and / or the alkaline earth metal oxide present in the electrochemical cell. The eutectic temperature refers to the minimum temperature at which the components of the electrochemical cell melt to form a single, homogenous liquid phase. In one aspect, the operating temperature of the electrochemical cell can be greater than the melting point of the alkali metal carbonate and / or the alkaline earth metal carbonate, but less than the melting point of the alkali metal oxide and / or alkali earth metal oxide. In some aspects, the operating temperature of the electrochemical cell comprising the alkali metal carbonate and / or the alkaline earth metal carbonate and the alkali metal oxide and / or the alkaline earth metal oxide can be greater than the melting points of all of the respective components present in the electrochemical cell. In other aspects, the operating temperature of the electrochemical cell comprising the alkali metal carbonate and / or the alkaline earth metal carbonate and the alkali metal oxide and / or the alkaline earth metal oxide can be less than the melting points of all of the respective components present in the electrochemical cell.

[0054] Representative and non-limiting ranges for the operating temperature of the electrochemical cell can include from 500 °C to 1000 °C, from 550 °C to 950 °C, from 600°C to 900 °C, from 650 °C to 875 °C, from 700 °C to 860 °C. or from 800 °C to 850 °C. One of ordinary skill in the art would recognize that the operating temperature of the electrochemical cell can be dependent on the composition of the alkali metal carbonate and / or the alkaline earth metal carbonate and the composition of the alkali metal oxide and / or alkali earth metal oxide. In a particular aspect of this invention, the temperature in the electrochemical cell is less than that of the mixture in the molten bath in step (i). In another particular aspect of this invention, the temperature in the electrochemical cell is greater than that of the mixture in the molten bath in step (i).

[0055] Beneficially, when an electrode is transferred from the electrochemical cell, there is no cool down period required before contacting the electrode with the mixture in the molten bath. As a non-limiting example, an electrode operating in an electrochemical cell at 500 °C to 1000 °C can be directly contacted with the molten bath mixture at a temperature of 500 °C to 1600 °C in step (i), without needing to be cooled down first. As a result, energyconsumption of the overall process can be significantly reduced since no drastic thermal swings (e.g.. cool down prior to re-heating) are required between the electrochemical cell and the molten bath.

[0056] Advantageously, in circumstances where a step of reducing the alkali metal carbonate and / or the alkaline earth metal carbonate in an electrochemical cell is performed prior to step (i), all or a portion of the alkali metal carbonate and / or the alkaline earth metal carbonate formed in step (iii) can be recycled to the electrochemical cell, making the disclosed processes cyclic or circular. Therefore, the processes disclosed herein can further comprise, after step (iii), a step of recy cling the alkali metal carbonate and / or the alkaline earth metal carbonate to the electrochemical cell. Additionally, in an aspect, no heating is needed or utilized for recycling the alkali metal carbonate and / or the alkaline earth metal carbonate back to the electrochemical cell.

[0057] It is also contemplated that the steps of the processes disclosed herein can be performed in the same vessel. Thus, and advantageously, steps (i)-(iii) can be performed in the same vessel. This is not a requirement, so alternatively, step (i) and step (iii) of the processes disclosed herein can be performed in a different vessel. It is also contemplated that one or more of the steps of the processes disclosed herein can be performed in an inert atmosphere comprising Ar, He, N2, or any combination thereof. Thus, step (i), step (ii), and / or step (iii) can be earned out in an inert atmosphere comprising Ar, He, N2, or any combination thereof, either individually or in any combination.

[0058] Referring now to FIG. 1. which illustrates process 100 for removing carbonaceous materials from an electrode and from oxide by-products that are co-deposited on the electrode. In process 100, electrochemical cell 105 comprises Li2CCh electrolyte 110 (and U2O electrolyte), cathode 115, and anode 120. IJ2CO3 electrolyte 110 dissociates into Li+and CCL2-ions in electrochemical cell 105. The CCL2-ions reduce at the interface of cathode 115 to form graphite 125 and oxide ions. The Li+ions reduce at the interface of cathode 115 and combine with oxide ions to form IJ2O 130. Cathode 115, which is at least partially covered with graphite 125 and U2O 130, is transferred from the electrochemical cell 105 and dipped into molten bath vessel 135 containing mixture 140 that comprises Li2CO? and Li2O. A portion of graphite 125 is removed, as a solid, from cathode 1 15 and dispersed into molten bath vessel 135. Concurrently, all or a portion of IJ2O 130 is removed, as a liquid, from cathode 115 and dissolved into molten bath vessel 135. Then, all or a portion of (solid) graphite 125 is removed from mixture 140 in molten bath vessel 135 by floatation and / or decanting 145. Next, superheated CO2 150 is sparged into molten bath vessel 135 through gas feed line 155 to convert all or a portion of the Li2O 130 to U2CO3. All or a portion of the Li2COs produced can be recycled to electrochemical cell 105 through recycle line 160 to replenish Li2COs electrolyte 110 in electrochemical cell 105. Optionally, no heating is needed or utilized for recycling the IJ2CO3 produced back to electrochemical cell 105.EXAMPLES

[0059] The invention is further illustrated by the following examples, which are not to be construed in any way as imposing limitations to the scope of this invention. Various other aspects, embodiments, modifications, and equivalents thereof which, after reading the description herein, may suggest themselves to one of ordinary' skill in the art without departing from the spirit of the present invention or the scope of the appended claims.EXAMPLE 1Thermal decomposition behavior of lithium carbonate (LijCOp

[0060] A thermogravimetric analysis (TGA) was conducted to evaluate the thermal stability and decomposition of lithium carbonate (Li2CO3). The Li2CO3 sample was heated under a flowing helium (He) atmosphere at a ramp rate of 20 °C per minute from 0 to 1000 °C using a TGA system coupled with a mass spectrometer (TGA-MS).

[0061] FIG. 2 presents an overlay of the TGA weight loss curve and the ion current signal corresponding to a mass-to-charge ratio (m / z) of 44, which is characteristic of carbon dioxide (CO2). The TGA curve (left y-axis) shows the percent weight loss of the Li2COs sample as a function of time (min) and temperature (°C). The ion current (mA) curve (right y-axis) indicates the signal intensity for CO2 detected by the mass spectrometer as the temperature increases.

[0062] As shown in FIG. 2, Li2CCh begins to lose mass near its melting point (723 °C). A pronounced increase in ion current for m / z 44 is observ ed between approximately 750 °C and 900 °C, confirming the evolution of CO2. This mass loss and gas evolution are consistent with the thermal decomposition of Li2COs to lithium oxide (IJ2O) and CO2, represented by the following formula:Li2COs - L12O + CO2 .

[0063] The weight loss of the Li2CO3 sample levels off by approximately 950 °C, indicating that the majority’ of the decomposition reaction has occurred by this point. These results establish an upper temperature threshold for the thermal stability of Li2CCh and demonstrate the importance of limiting the operating temperature in both molten baths and electrochemical cells containing Li2CCh in order to avoid parasitic CO2 evolution and degradation of the molten composition in each system. This thermal behavior supports the disclosed processes which rely on effective carbon deposition and regeneration.EXAMPLE 2Thermal behavior and carbon dioxide (CO2) uptake of lithium oxide (Li2O)

[0064] A thermogravimetric analysis (TGA) was conducted to evaluate the carbon dioxide (CO2) uptake behavior of lithium oxide (Li2O). The Li2O sample was heated under a flowing CO2 atmosphere at a ramp rate of 20 °C per minute from 0 to 750 °C using a TGA system. FIG. 3 presents the TGA weight curve showing the percent weight gain of the Li2O sample as a function of time (min) and temperature (°C).

[0065] As shown in FIG. 3, the Li2O sample exhibits a significant increase in weight upon heating in the presence of CO2, indicating formation of lithium carbonate (Li2CC>3) via reaction with the CO2 gas. Upon further heating beyond approximately 475 °C, additional weight gain is observed, reflecting continued CO2 uptake at elevated temperatures. The thermal behavior of the Li2O sample is consistent with enhanced surface reactivity and solid- state diffusion.

[0066] These results demonstrate that Li2O can absorb CO2 in the solid state and form L12CO3 through the following reaction:Li2O + CO2 - Li2COs .

[0067] The thermal behavior of Li2O supports the regeneration step (iii) of the disclosed processes, in which CO2 is introduced into the molten bath following the removal of all or a portion of the carbonaceous material from the electrode. The observed reactivity of Li2O with CO2 confirms that the molten bath can be effectively re-carbonated, enabling continuous or cyclic operation.EXAMPLE 3Operating window for a molten lithium carbonate (Li2COs) and lithium oxide (Lid)) system

[0068] A phase diagram was constructed to define the operating window for molten mixtures of lithium carbonate (Li2CC>3) and lithium oxide (Li2O). FIG 4 presents a phase diagram showing the operating temperature and composition phase behavior of the LizCOs and Li2O system, where the y-axis represents temperature in Kelvin and the x-axis represents mol % Li2O, such that pure Li2CO3 is located at 0 mol % Li2O on the far left, and the Li2CO3 content decreases as the Li2O concentration increases along the x-axis.

[0069] As shown in FIG. 4, a fully molten region exists between approximately 5 to 15 mol % Li2O. Within this window, the mixture remains fully liquid betw een about 975 K to about 1075 K (about 700 °C to about 800 °C). Operating within this composition and temperature range allows for effective melt handling while minimizing thermal decomposition of Li2CO3. A eutectic point occurs at around 13.1 mol % Li2O (which corresponds to approximately 5.7 wt. % Li2O), where the mixture achieves its lowest fully molten temperature near 975 K (about 700 °C). This eutectic composition defines a preferred operating point for the Li2COs and Li2O system because it enables complete melting of the mixture at a minimum temperature. These results support the disclosed processes by identifying a stable region and eutectic point for the molten bath (and optionally the electrochemical cell) when Li2CO and Li2O are utilized.EXAMPLE 4

[0070] A molten metal bath was prepared comprising a mixture of lithium oxide (Li2O) and lithium carbonate (Li2CO3), with relative amounts of Li2O and Li2COs being approximately 5.7 wt. % Li2O and 94.3 wt. % Li2COs, respectively. The molten bath mixturewas held at a temperature of 750 °C. An electrode that was partially covered with a carbonaceous material and Li2O was transferred from an electrochemical cell and then immersed into the molten bath mixture. For portions of the experiment, a lid was placed on top of the vessel containing the molten bath mixture and the electrode to create a closed system, helping to maintain heat and reduce loss of carbon dioxide (CO2) from any decomposition of Li2COs.

[0071] After immersion, a portion of the Li2O was removed as a liquid from the electrode and dissolved into the molten bath mixture. Surprisingly, a portion of the carbonaceous material was removed as a solid from the electrode and dispersed into the molten bath mixture, while a portion of the carbonaceous material remained on the electrode.

[0072] A sample of the carbonaceous material taken from the electrode was removed for analysis. The sample of carbonaceous material was analyzed using transmission electron microscopy (TEM). FIG. 5 and FIG. 6 show representative TEM images of the recovered carbonaceous material. The TEM images show carbon-rich structures on the submicron- scale. Elemental information obtained through the TEM analysis indicated the presence of carbon, as well as oxygen, aluminum, chromium, nickel, and iron. These additional elements are believed to be impurities introduced during processing. The sample of carbonaceous material was further analyzed by X-ray diffraction (XRD), which confirmed the presence of carbon in the material.

[0073] The invention is described herein with reference to numerous aspects and specific examples. Many variations will suggest themselves to those skilled in the art in light of the detailed description. All such obvious variations are within the full intended scope of the appended claims. Other aspects of the invention can include, but are not limited to, the following (aspects are described as “comprising’’ but, alternatively, can “consist essentially of’ or “consist of’):

[0074] Aspect 1. A process comprising: (i) contacting an electrode at least partially covered with a carbonaceous material and an alkali metal oxide and / or an alkaline earth metal oxide, and a molten bath comprising a mixture of an alkali metal carbonate and / or an alkaline earth metal carbonate with the alkali metal oxide and / or the alkaline earth metal oxide; wherein all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide is removed as a liquid from the electrode and dissolved into the molten bath, and a portion of the carbonaceous material is removed as a solid from the electrode and dispersed into the molten bath; (ii) removing all or a portion of the carbonaceous material from the molten bath;and (iii) introducing CO2 into the molten bath to convert all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide to the alkali metal carbonate and / or the alkaline earth metal carbonate.

[0075] Aspect 2. The process defined in aspect 1, wherein the temperature of the mixture in step (i) is a temperature sufficient to remove (via melting and / or dissolution) all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide (as a liquid) from the electrode.

[0076] Aspect 3. The process defined in aspect 1 or 2, wherein the temperature of the mixture in step (i) is less than the melting point of the carbonaceous material.

[0077] Aspect 4. The process defined in any one of aspects 1-3, wherein the temperature of the mixture in step (i) is greater than the melting temperature (e.g., eutectic point) of the mixture.

[0078] Aspect 5. The process defined in any one of aspects 1-4, wherein the temperature in step (ii) is substantially the same (+ / - 100 °C) as the temperature of the mixture in step (i).

[0079] Aspect 6. The process defined in any one of aspects 1-5, wherein the temperature in step (iii) is substantially the same (+ / - 100 °C) as the temperature of the mixture in step (i).

[0080] Aspect 7. The process defined in any one of aspects 1-6. further comprising, prior to step (i), a step of reducing the alkali metal carbonate and / or the alkaline earth metal carbonate in an electrochemical cell to the carbonaceous material and the alkali metal oxide and / or the alkaline earth metal oxide.

[0081] Aspect 8. The process defined in aspect 7, wherein the temperature in the electrochemical cell is less than that of the mixture in step (i).

[0082] Aspect 9. The process defined in aspect 7 or 8, further comprising, after step (iii), a step of recycling the alkali metal carbonate and / or the alkaline earth metal carbonate to the electrochemical cell.

[0083] Aspect 10. The process defined in aspect 9, wherein no heating is utilized for recycling the alkali metal carbonate and / or the alkaline earth metal carbonate to the electrochemical cell.

[0084] Aspect 11. The process defined in any one of aspects 1-10, wherein the alkali metal oxide comprises Li2O and the alkali metal carbonate comprises Li2CO3.

[0085] Aspect 12. The process defined in any one of aspects 1-10, wherein the alkali metal oxide comprises Na2O and the alkali metal carbonate comprises Na2CO?.

[0086] Aspect 13. The process defined in any one of aspects 1-10, wherein the alkali metal oxide comprises K2O and the alkali metal carbonate comprises K2CO3.

[0087] Aspect 14. The process defined in any one of aspects 1-10, wherein the alkaline earth metal oxide comprises MgO and the alkaline earth metal carbonate comprises MgCCh.

[0088] Aspect 15. The process defined in any one of aspects 1-10, wherein the alkaline earth metal oxide comprises CaO and the alkaline earth metal carbonate comprises CaCO3

[0089] Aspect 16. The process defined in any one of aspects 1-10, wherein the alkaline earth metal oxide comprises SrO and the alkaline earth metal carbonate comprises SrCO3.

[0090] Aspect 17. The process defined in any one of aspects 1-10, wherein the alkaline earth metal oxide comprises BaO and the alkaline earth metal carbonate comprises BaCCh.

[0091] Aspect 18. The process defined in any one of aspects 1-17, wherein the carbonaceous material comprises graphite, graphene, carbon black, amorphous carbon, activated carbons, carbon nanotubes, carbon (nano)fibers. fullerenes, or any combination thereof.

[0092] Aspect 19. The process defined in any one of aspects 1-17, wherein the carbonaceous material comprises graphite (with any suitable degree of graphitization), a graphitizable material (which is convertible to graphite in a furnace), or any combination thereof.

[0093] Aspect 20. The process defined in any one of aspects 1-19, wherein in step (ii), all or a portion of the carbonaceous material is removed from the molten bath using any suitable technique or any technique disclosed herein, e.g., extracting, decanting, floatation, pressing, settling (density differences), centrifuging, filtering, draining, or any combination thereof.

[0094] Aspect 21. The process defined in any one of aspects 1-20, wherein the electrode is a cathode.

[0095] Aspect 22. The process defined in aspect 21. wherein the cathode comprises titanium, stainless steel, graphite, a metal super alloy comprising two or more of Ni, Cr, Fe, and / or Mo, or any combination thereof.

[0096] Aspect 23. The process defined in any one of aspects 1-22, wherein the CO2 in step (iii) is superheated.

[0097] Aspect 24. The process defined in any one of aspects 1-23, wherein step (i) and step (iii) are performed in a different vessel.

[0098] Aspect 25. The process defined in any one of aspects 1-23, wherein steps (i)- (iii) are performed in the same vessel.

[0099] Aspect 26. The process defined in any one of aspects 1-25, wherein step (i). step (ii), and / or step (iii) are performed in an inert atmosphere comprising Ar, He, N2, or any combination thereof.

Claims

CLAIMSWhat is claimed is:

1. A process comprising:(i) contacting an electrode at least partially covered with a carbonaceous material and an alkali metal oxide and / or an alkaline earth metal oxide, and a molten bath comprising a mixture of an alkali metal carbonate and / or an alkaline earth metal carbonate with the alkali metal oxide and / or the alkaline earth metal oxide; wherein all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide is removed as a liquid from the electrode and dissolved into the molten bath, and a portion of the carbonaceous material is removed as a solid from the electrode and dispersed into the molten bath;(ii) removing all or a portion of the carbonaceous material from the molten bath; and(iii) introducing CO2 into the molten bath to convert all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide to the alkali metal carbonate and / or the alkaline earth metal carbonate.

2. The process of claim 1, wherein a temperature of the mixture in step (i) is a temperature sufficient to remove all or a portion of the alkali metal oxide and / or the alkaline earth metal oxide from the electrode.

3. The process of claim 1 or 2, wherein a temperature of the mixture in step (i) is less than a melting point of the carbonaceous material.

4. The process of any one of claims 1-3, wherein a temperature of the mixture in step (i) is greater than a melting temperature of the mixture.

5. The process of any one of claims 1-4, wherein a temperature in step (ii) is substantially the same as a temperature of the mixture in step (i).

6. The process of any one of claims 1-5, wherein a temperature in step (iii) is substantially the same as a temperature of the mixture in step (i).

7. The process of any one of claims 1-6, further comprising, prior to step (i), a step of reducing the alkali metal carbonate and / or the alkaline earth metal carbonate in an electrochemical cell to the carbonaceous material and the alkali metal oxide and / or the alkaline earth metal oxide.

8. The process of claim 7, wherein a temperature in the electrochemical cell is less than (or greater than) that of the mixture in step (i).

9. The process of claim 7 or 8, further comprising, after step (iii), a step of recycling the alkali metal carbonate and / or the alkaline earth metal carbonate to the electrochemical cell.

10. The process of claim 9, wherein no heating is utilized for recycling the alkali metal carbonate and / or the alkaline earth metal carbonate to the electrochemical cell.

11. The process of any one of claims 1-10, wherein an amount of the alkali metal oxide and / or the alkaline earth metal oxide present in the mixture in step (i) is in a range from 2 to 28 mol %, from 5 to 25 mol %, from 8 to 20 mol %, from 10 to 18 mol %, or from 12 to 15 mol %, based on total moles of the alkali metal carbonate and / or an alkaline earth metal carbonate and the alkali metal oxide and / or the alkaline earth metal oxide in the mixture.

12. The process of any one of claims 1-11, wherein the alkali metal oxide comprises Li2O and the alkali metal carbonate comprises LnCCh.

13. The process of claim 12, wherein an amount of the Li2O present in the mixture in step (i) is from 12 to 15 mol %, based on total moles of the L12O and the Li2COs in the mixture.

14. The process of claim 12 or 13, wherein a temperature of the mixture in step (i) is in a range from 675 to 725 °C.

15. The process of any one of claims 12-14, wherein in step (iii), CO2 is introduced into the molten bath to convert all or a portion of the Li2O to the Li2CO3.

16. The process of any one of claims 1-11, wherein: the alkali metal oxide comprises Na20 and the alkali metal carbonate comprises Na2COs; the alkali metal oxide comprises K2O and the alkali metal carbonate comprises K2CO3; the alkaline earth metal oxide comprises MgO and the alkaline earth metal carbonate comprises MgCCh: the alkaline earth metal oxide comprises CaO and the alkaline earth metal carbonate comprises CaCCh; the alkaline earth metal oxide comprises SrO and the alkaline earth metal carbonate comprises SrCOs; or the alkaline earth metal oxide comprises BaO and the alkaline earth metal carbonate comprises BaCCh.

17. The process of any one of claims 1-16, wherein the carbonaceous material comprises graphite, graphene, carbon black, amorphous carbon, activated carbons, carbon nanotubes, carbon (nano)fibers, fullerenes, or any combination thereof.

18. The process of any one of claims 1-16, wherein the carbonaceous material comprises graphite, a graphitizable material, or any combination thereof.

19. The process of any one of claims 1-18, wherein in step (ii), all or a portion of the carbonaceous material is removed from the molten bath via extracting, decanting, floatation, pressing, settling, centrifuging, filtering, draining, or any combination thereof.

20. The process of any one of claims 1-19, wherein the electrode is a cathode.

21. The process of claim 20, wherein the cathode comprises titanium, stainless steel, graphite, a metal super alloy comprising two or more of Ni. Cr, Fe, and / or Mo. or any combination thereof.

22. The process of any one of claims 1-21, wherein the CO2 in step (iii) is superheated.

23. The process of any one of claims 1-22, wherein step (i) and step (iii) are performed in a different vessel.

24. The process of any one of claims 1-22, wherein steps (i)-(iii) are performed in the same vessel.

25. The process of any one of claims 1-24, wherein step (i). step (ii), and / or step (iii) are performed in an inert atmosphere comprising Ar, He, N2, or any combination thereof.

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