Electrochemical cell for metal oxidation, corresponding system and method

Abstract

The disclosure relates to an electrochemical structure composed of a first electrode (A1), a second electrode (C2), an electrolyte (E4) and an anionic transport layer (CTA) in which the anionic transport layer (CTA) is never in direct contact with the electrodes A1 and C2 at the same time, and the electrolyte E4 is an inorganic material solid at room temperature and composed of anions and cations.

Description

Description Title of the invention: Electrochemical cell for metal oxidation, corresponding system and method Field of the invention

[0001] L’invention se rapporte à la production de métaux. L’invention se rapporte à more particularly to the production of metals by an electrochemical method. The invention relates more particularly to the electrolysis of metals under conditions unfavorable to the use of liquid electrolyte. Prior Art

[0002] La métallurgie rejette une quantité considérable de CO2, dont la production de fer only represents about 7% of global emissions. Current industrial processes rely on the carbothermic process, which uses graphite for the reduction of oxides at high temperatures according to the following formula:

[0004] Cependant, cette technologie n’est pas compatible avec les ambitions de neutralité carbon.

[0005] L’alternative qui se présente s’appuie sur des technologies d’électrolyses hautesTemperatures. Three types of metal oxide electrolyzers are currently being explored: Fray-Farthing-Chen (FFC) Cambridge process and Hall-Héroult, by direct reduction of a metal oxide dissolved in a molten salt (700°C–1100°C); Metal Oxide Electrolysis (MOE), by direct reduction of the metal oxide in its liquid form (1400°C–1600°C); and calciothermic electrolysis, by indirect reduction of the metal oxide (700°C–900°C). Several companies have positioned themselves in this field, including Boston Metal® with MOE technology and Metalysis® with FFC technology.

[0006] Ainsi, les technologies FFC et Hall-Héroult sont une réduction directe des oxides metallic with the dissolution of metal oxides in a molten salt. The metal ions are reduced at the cathode and the oxygen ions are removed at the anode as dioxygen (WO1999064638A1).

[0007] Par ailleurs, la technologie de Boston Metal® « Électrolyse de l'oxyde fondu"(MOE) for steel production is a direct electrolysis process without the addition of molten salt, eliminating the need for coal in steel production (US8764962B2, WO2019055910A1). The developed MOE process and platform can use renewable electricity to convert iron ore into liquid metal. This direct approach eliminates several steps in the steelmaking process, thus avoiding coke production, iron ore sintering and pelletizing, blast furnace reduction, or refining in an oxygen basic converter." In the MOE platform, an inert anode is immersed in an electrolyte containing iron ore and then electrified. When the cell reaches a temperature of 1600°C, the electrons reduce the iron oxide in the ore, producing pure liquid metal at the cathode. There is no carbon dioxide or other harmful byproducts; the only byproduct produced is oxygen released at the anode. The overall reaction is as follows:

[0008]

[0009] De plus, la plateforme et la cellule MOE ne nécessite pas d'eau de traitement, de hazardous chemicals or precious metal-based catalysts. The result is a clean, high-purity liquid metal that can be sent directly to ladle metallurgy – no reheating is required.

[0010] Enfin, il existe les technologies de réduction indirecte basées sur la production d’un A strongly reducing precursor in molten salt (US20220145484A1, Carpenter 2022) is used. Calciothermic techniques are generally employed. Once formed at the cathode, the precursor then reduces the metal oxide to its metallic form.

[0011] D’autres acteurs se sont également positionnés pour l’utilisation in-situ du régolithe for space exploration, particularly for the production of oxygen and metals for the construction of equipment on the lunar surface.

[0012] Cependant, les technologies d’électrolyse pour la réduction des oxydes souffrent relatively low conversion yields, mainly due to the presence of ionic loops where species are reduced at the cathode (e.g., Fe 2+ ) are reoxidized at the anode (e.g., Fe 3+ ) because of significant diffusion in a liquid electrolyte, and operate at high temperatures (1600°C) which has the effect of reducing the range of compatible materials for the design of the electrolysis cell.

[0013] Par ailleurs, les interfaces gaz / liquide sont problématiques dans une cellule electrolysis occurs in the absence of or under low gravity. Indeed, the detachment of gas bubbles from the electrodes is reduced, which induces an accumulation of gas that blocks electrochemical reactions in the absence of gravity.

[0014] Il est donc souhaitable de disposer de solutions permettant d’améliorer le rendementconversion during the electrolysis of metal oxides, lowering the temperature for the implementation of the electrolysis cell and which is better suited to implementation conditions under low gravity by the suppression of a liquid phase.

[0015] L’invention vient améliorer la situation. Summary of the invention

[0016] L’invention vient améliorer la situation. Plus particulièrement, l’invention autorise la implementation of a metal reduction process at relatively low temperature, without necessarily requiring a liquid electrolyte, which allows for the production of metal even in the absence of gravity or in the presence of low gravity. More specifically, the disclosure relates to an electrochemical cell for the reduction of metal oxides comprising a chamber in which a first electrode and a second electrode are positioned, said cell further comprising means for heating the internal volume of said chamber, the cell being configured to receive an electrolyte in a (singular) solid form. According to the invention, at least one ion transport layer is located between the first electrode and / or the second electrode and the (singular) solid electrolyte.

[0017] Selon une caractéristique particulière la couche de transport anionique (CTA) estThe anion transport layer is designed to transport anions from the solid electrolyte to a first electrode while preventing this electrode from being blocked by the production of the gaseous phase at its surface. For example, the anion transport layer is designed to transport anions to the anode while preventing the oxidation reaction from being blocked by the gaseous phase produced at the anode.

[0018] Selon une caractéristique particulière les moyens de chauffage du volume interne de said enclosures are configured to deliver a temperature between 500°C and 1200°C.

[0019] Selon une caractéristique particulière, l’électrolyte sous une forme solide est un glass.

[0020] Selon une caractéristique particulière, le verre appartient au groupe comprenant : Soda-lime glass; borosilicate glass, fused silica, regolith glass. More generally, it refers to any other amorphous material characterized by a glass transition point (T g ) and a melting point (T m ), such that T g is less than T m , offering within this interval a working temperature range for redox reactions.

[0021] Selon une caractéristique particulière, ladite au moins une couche de transportanionic belongs to the group including: –molten salts, such as calcium chloride (CaCl2); – eutectics (of molten salts), such as lithium and potassium carbonates (Li2CO3-K2CO3), so as to lower the melting point; –metals of column 11 of the periodic table of elements such as silver (Ag) or gold (Au); –solid anion-conducting membranes with for example yttrium oxide-stabilized zirconia (YSZ).

[0022] Selon une caractéristique particulière, la première électrode est une anode et la The second electrode is a cathode.

[0023] Selon un autre aspect, l’invention se rapporte également à un procédé d’électrolyse of an electrolyte in solid form. This process includes the implementation of an electrochemical cell as described above, within which the electrolyte in solid form is inserted.

[0024] Selon une caractéristique particulière, le procédé comprend plus particulièrement :– A step of inserting the electrolyte in solid form into the electrochemical cell; – A step of adding the anionic transport layer to the interface between the first electrode and the electrolyte in solid form; – A step of hermetically sealing the electrochemical cell; – A heating step, using the M3 heating means, to reach a temperature between the glass transition temperature and the melting temperature of the electrolyte in solid form; – A step of applying a current setpoint to the electrode terminals with a current generator, the current density being selected to initiate the redox process.

[0025] Ainsi, la cellule électrochimique de la divulgation peut être utilisée pour produire,For example, using lunar regolith, metals, and oxygen, and utilizing energy produced in situ (e.g., from solar energy). Since regolith is composed of 99% oxygen, sodium, magnesium, aluminum, silicon, titanium, and iron, it is well-suited for the implementation of the electrochemical cell described in this disclosure. Other implementations of the electrochemical cell can obviously be developed depending on the requirements.

[0026] Selon un autre aspect, l’invention se rapporte également à la conduite de l’électrolyseusing a cell as previously described. Such a system includes the implementation of a computer program executable by a processor, on an electronic control board connected to the various means implemented for the use of the previously described cell. This computer program controls the implementation of the redox reaction of the electrolyte in solid form, notably by controlling the temperature within the cell enclosure, controlling the application of current commands to the electrode terminals, activating the means for extracting the gases produced during the redox reaction, and signaling the end of the reaction when certain measured values ​​indicate it. Brief description of the figures

[0027] D'autres caractéristiques et avantages de la divulgation apparaîtront plus clairementupon reading the following description of a particular embodiment, given by way of simple illustrative and non-limiting example, and the accompanying drawings, among which: – [Fig. 1] schematically illustrates an electrochemical cell of the invention; – [Fig. 2a] and [Fig. 2b] illustrate the implementation of a first configuration of the electrochemical cell; – [Fig. 3a] and [Fig. 3b] illustrate the implementation of a second configuration of the electrochemical cell; – [Fig. 4a] and [Fig. 4b] illustrate the implementation of a third configuration of the electrochemical cell; – [Fig. 5] illustrates the current as a function of the voltage applied across the electrodes with vitrified regolith in a test of a configuration of the cell of the invention; –[Fig.6a] and [Fig.6b] illustrate the use of a configuration of the cell of the invention with on the one hand a liquid anionic transport layer and on the other hand a solid anionic transport layer.

[0028] Description d’un mode de réalisation

[0029] Comme indiqué ci-dessus, les techniques actuelles de réduction électrolytiques n’ontThe current conversion efficiency of Hall-Héroult cells is poor, and / or they operate at high temperatures (>1200°C), and / or they use components that are extremely hazardous to human health, such as fluorinated compounds, and / or they are not suitable for low-severity situations. In this context, the disclosed technique involves the use of a method that allows operation at acceptable temperature levels (between 500°C and 1200°C) and current conversion efficiency levels close to 90% (Faraday efficiency). This technique can also be implemented with numerous oxides or anionic transport layers, and the results obtained are illustrated herein.

[0030] Selon la divulgation, il est décrit, en relation avec la [Fig.1], une vue de coupe d’uneA metal oxidation electrochemical cell (CEL) comprises a chamber E0 within which a first electrode A1 and a second electrode C2 are positioned. The electrochemical cell further comprises heating means M3 for the internal volume of said chamber. The electrochemical cell is configured to receive an electrolyte E4 in a solid form, for example. According to the disclosure, the first electrode A1 and / or the second electrode C2 is at least partially coated with an anionic transport layer (CTA).

[0031] Le contact entre l’électrolyte solide E4 introduit au sein de l’enceinte de la The electrochemical cell and the first electrode A1 are indirect. This is achieved via the anion transport layer (ATL). The function of the ATL is to transport anions towards the anode without blocking the gaseous phase produced at the anode interface, as detailed later.

[0032] Selon la divulgation, l’électrolyte sous une forme solide E4 introduit au sein deThe enclosure is made of glass. For the purposes of this implementation, glass is an amorphous material characterized by the absence of a crystalline lattice. This type of glass could, for example, be soda-lime glass (SLG), which primarily comprises silicon dioxide (SiO2), sodium hydroxide (Na2CO3), and lime (CaO). It could also be borax silicate glass, a type of glass that contains silicon dioxide (SiO2) and boron oxide (B2O3) in its chemical composition. It could also be fused silica, also known as fused silica or fused quartz glass, obtained from silicon dioxide (SiO2). In a space application, it could also be regolith glass, a type of glass formed naturally from the melting of regolith, for example, on the lunar surface.

[0033] De plus, la mise en œuvre de la cellule électrochimique peut également présenter uninterest in nano- or microcrystalline materials or crystals. However, glasses exhibit very distinct transition temperatures (T m and T g ) which are not necessarily found in the crystals. As explained later, the temperature of the CEL electrochemical cell should therefore be precisely controlled for these materials.

[0034] Ainsi, la cellule électrochimique CEL pour la réduction de métaux comprend, dansAt least one implementation includes the following elements: – A refractory enclosure E0, made of a high-temperature resistant material such as alumina or zirconia, to contain the cell and thermally insulate the system. – An anode A1, made of graphite or refractory metal, where anion oxidation takes place. Graphite is a material that is generally consumed and releases CO2 when the anion is oxygen, whereas refractory metals are ideally used for inert anodes that are not consumed and have a relatively low wear rate. – A cathode C2, made of conductive metal or alloy, where metal ion reduction occurs. – A heating system M3 (which can be external), such as a resistive or induction furnace, to maintain the cell at the required operating temperature (e.g., between 500 and 1200°C). – At least one anion transport layer (ATL), as explained previously. –A solid electrolyte E4, in the form of a glass.– Current collectors C5, for example made of stainless steel, connected to electrodes A1 and C2 to collect electrons and allow the flow of electric current. – Seals J6 made of refractory material, such as mica or azirconia, to ensure the cell is airtight and prevent gas leaks, particularly of oxygen produced by the reaction. – A gas extraction system S7 to extract the gases produced (for example, O2) from the cell.

[0035] Cette structure permet de créer un environnement contrôlé pour la réduction The electrochemical process of vitrified metal oxides maximizes anodic action by transporting anions out of the solid electrolyte. The dimensions of this cell are adapted to specific needs and configurations. The internal volume for receiving the solid E4 electrolyte can range from a few cubic decimeters to several tens of cubic decimeters.

[0036] La technique proposée permet ainsi de réaliser l'électrolyse du matériau (du verre) over a temperature range T such that with Tg the transition temperature of the glass and Tm the melting temperature of the glass.

[0037] On rappelle à toute fins utiles que la température de transition du verre, égalementKnown as the glass transition temperature (Tg), this is the temperature at which a glassy material transitions from a rigid solid to a rubbery, elastic state. This transition occurs when the molecular chains of the glass begin to move and rearrange in response to increasing temperature. Below the glass transition temperature, the glass is in a rigid, solid state with a disordered, amorphous molecular structure. Above the glass transition temperature, the glass becomes softer and more elastic, with a more fluid and mobile molecular structure. The glass transition temperature is typically between 500°C and 1200°C for common glasses and varies depending on the glass's composition and molecular structure. The melting temperature of glass (Tm) is the temperature at which a glassy material transitions from a solid to a liquid state.This temperature depends on the chemical composition and molecular structure of the glass, as well as the heating rate during the melting process. When glass is heated to its melting temperature, the molecular chains begin to break down and reorganize, resulting in a loss of viscosity and increased fluidity. The following table illustrates the temperature ranges for the glasses described above: Tg (°C) Tm (°C) Soda-Lime Glass 500 1000 Boro-Silicate Glass 700 1200 Fused Silica 1200 2200 Regolith Glass 600 1200.

[0038] Dans ces plages de température, en fonction du verre mis en œuvre, la conductivité ionic activity is activated and electrochemical reactions are possible with the reduction of cations (C m+ ) to the cathode and the oxidation of anions (A n- ) to the anode.

[0039] On rappelle que la conductivité ionique est différente de la conductivité électrique :Although the two quantities are often expressed with the same symbols (σ - sigma) and units (S / cm), these two conductivities are different. Ionic conductivity is generated by the movement of ions under the influence of an electric field. This ion movement occurs in an electrolyte such as solids and solutions. Ionic conductivity is measured with signals on the order of kHz. In contrast, electrical conductivity is generated by the movement of charge carriers such as electrons or holes in a metal or semiconductor. Electrical conductivity can be measured with direct current (DC) or alternating current (AC) signals. Both conductivities can sometimes be found in the same medium, particularly at temperatures above 1000°C. However, at room temperature, ionic conduction can be considered the only type of conduction through an electrolyte.

[0040] Comme indiqué précédemment, l'architecture de la cellule électrochimique estadapted to allow the evacuation of the gaseous phase generated at the anode. Indeed, the viscosity of the glass over this temperature range does not allow the gas bubbles to be released from the electrode (anode)-glass interface.

[0041] La cellule électrochimique ainsi décrite peut fonctionner sur des gammes de courantRelatively high (~0.1–2 A / cm²) values ​​are required for the reduction of vitrified metal oxides within a relatively low temperature range (500–1200°C). The solid electrolyte E4 can be shaped like a singularly cylindrical bar of unlimited diameter and length. The electrodes (A1 and C2) are positioned at each end of the cylindrical bar. The CTA, described below, is positioned between the anode and the cylindrical bar. The potential applied between the electrodes is singularly proportional to the equivalent resistance induced by the cylindrical bar. The ionic conductivity of the glass is estimated to be between 0.1 and 1 S / cm over the considered temperature range. The Joule heating effect generated through the cylindrical bar maintains the cell at temperature.

[0042] Par ailleurs, certains verres comprennent des éléments volatils sous leur formemetallic reduced at the cathode with, for example, metallic sodium which evaporates at a temperature of 883°C and magnesium which evaporates at a temperature of 1090°C. For this reason, the inventors determined that it is advantageous to work at relatively low temperatures T, between the vaporization temperature of the most volatile elements.

[0043] Plus particulièrement, en considérant que pour T compris entre la When ionic conductivity is activated, the constituent elements of the glass, particularly cations, can be reduced at the cathode according to the reaction:

[0044]

[0045] avec , la phase du cation et, les anions peuvent être oxydés à the anode according to the reaction:

[0047] Cependant la forme A° est une forme gazeuse qui ne peut être properly evacuated from the glass / anode interface over the temperature range considered.

[0048] Afin d'améliorer cette interface une couche de transport des anions CTA estintroduced according to the invention. The CTA's function is to transport anions to the anode without blocking the generation and evacuation of the gaseous phase produced at the interface between the metal oxide and the anode. The CTA can be a molten salt (NaCl, CaCl2, etc.), a eutectic (for example, a mixture of salts) with low viscosity, a liquid metal (e.g., silver, gold), or a solid such as Yttrium Stabilized Zirconia (YSZ). The CTA is selected according to the operating range defined by the glass's Tg and Tm temperatures.

[0049] Par exemple, un eutectique tel que CaCl2-NaCl est un bon CTA lorsque Tg < 900°C. The liquid eutectic layer between the solid electrolyte E4 and the anode A1 is between 0.1 cm and 5 cm thick. Liquid silver is more suitable for temperatures 1000°C < Tg < 2000°C, such as for fused silica, as liquid silver has a higher boiling point than salts. Similarly, the liquid metal layer acting as the CTA is between 0.1 cm and 5 cm thick.

[0050] Lorsqu’une CTA métallique est désirée, celle-ci est sélectionnée au sein de lacolumn 11 of the periodic table of elements, with an intermediate melting point (900-1100°C) and a high oxidation potential (difficult to oxidize).

[0051] Lorsqu’une phase liquide n'est pas désirée alors le CTA peut être une membrane A solid anion-conducting membrane onto which an electrode is sintered. Such a membrane allows only anions to pass through and conducts them to the anode. For example, technologies developed for solid oxide fuel cells (SOFCs) can be adopted using YSZ / LSM type half-cells (from the English for "Lanthanum"). strontium manganite”) or YSZ / Ni or other to remove the oxygen produced at the interface with the glass in the case where the anion of the glass is the oxygen ion (O 2- ). The YSZ membrane operates over temperature ranges of 500 to 1100°C and the membrane thickness is between 10µm and 5 mm.

[0052] Aussi, si les propriétés du verre le permettent, une anode spécifique, singulièrementA porous anode, allowing the evacuation of gases produced by the oxidation reaction, can be prepared directly on the glass surface. For example, the use of a porous anode specifically designed for the electrolysis of glasses below their melting point can be considered. The porous anode is configured to oxidize anions and vent gases from the reactive interface. This option reduces the need for a heat treatment unit (HTU).

[0053] Le CTA peut également, dans certaines situations être le verre lui-même dans lequel a temperature gradient is applied such that the temperature T < Tm at the cathode but T > Tm at the anode.

[0054] Avec l'introduction de la CTA et l'électrolyse du verre pour , l'efficacité The faradic conversion rate, which is the level of electrochemical conversion of electrons injected into the system, is estimated to be close to 90%. Indeed, the inventors determined that under these conditions, the evolution of gases at the cathode is suppressed, as are electrical conductivity through the electrolyte and ionic loops within the electrolyte.

[0055] Ainsi, la technique décrite permet d’exploiter les propriétés des verres sur cettetemperature range for the production of metals, particularly under variable gravitational conditions (in the absence of gravity or with low gravity, where conventional liquid electrolytes cannot be used), as well as in the nuclear industry.

[0056] Les figures 2a à 4b illustrent plusieurs exemples de réalisation de la cellule electrochemical of the invention, wherein several anionic transport layers and several electrochemical cell configurations are shown (the electrochemical cell configurations are shown in cross-sectional view). The heating means are not shown in these figures.

[0057] La [Fig.2a] illustre une vue de coupe d’un premier exemple de configuration de laElectrochemical cell (ECC) in a three-electrode setup. In this first example, the ECC comprises a graphite anode (A1) in a vertical position, extending into the upper part of the ECC. The ECC also includes a graphite cathode (C2) forming a horizontal base. Finally, a reference electrode (e-ref55) is pre-introduced into the soda-lime glass (SLG) by heating it above its melting point (Tm). The reference electrode is a nickel-chromium wire. A temperature probe (Stemp) is also introduced. The electrochemical reaction volume is delimited by a cylindrical enclosure E0 made of alumina, which acts as an insulator. In this embodiment, the electrochemical cell is biased at 2 Volts between the cathode and the anode while a reading of the reference electrode potential is taken.

[0058] Le volume de réaction de la cellule CEL comprend une couche d’étain à l’état liquide(under heating), in contact with the graphite cathode C2, the soda-lime glass SLG, whose reduction is to be carried out, and calcium chloride CaCl2 (eutectic) in contact with the anode A1 which acts as the CTA. As illustrated in [Fig. 2b], the potential of the reference electrode stabilizes around T σ =250°C during heating. For T < T σ The reference electrode is floating. An S → L transition is visible and corresponds to the solid-liquid transition of CaCl2 at 772°C. In the configuration described in [Fig.2a] and whose result is presented in [Fig.2b], soda-lime glass (SLG) is considered to behave as a material without viscosity, i.e. with an infinite coefficient, below the melting point Tm (~1000°C), but whose ionic conductivity is activated from 250°C when the potential of the reference electrode is stabilized, as illustrated in [Fig.2b].

[0059] La [Fig.3a] illustre un deuxième exemple de configuration de la celluleelectrochemical cell CEL in which two electrodes are used. The electrochemical cell CEL thus comprises an anode A1, in a vertical position penetrating the upper part of the cell CEL. The cell CEL also comprises a cathode C2, forming a horizontal base of the cell CEL. The electrochemical reaction volume is delimited by a cylindrical enclosure E0 made of alumina, acting as an insulator. In this embodiment, the electrochemical cell CEL also includes the temperature measurement device D3. The reaction volume of the cell CEL comprises soda-lime glass SLG with a base approximately 2 cm thick and approximately 3 cm in diameter, which is to be reduced on the cathode C2, and a mixture of lithium and potassium carbonates Li2CO3-K2CO3 (eutectic) acting as the CTA in contact with the anode A1 and the soda-lime glass SLG E4. [Fig.Figure 3b] represents the temperature, current density, and voltage measurements between the cathode and anode over a 50-minute period. It can be noted that the cell voltage tends to decrease at constant current density and stabilizes between 20 and 30 V. The maximum current density during this configuration is approximately 0.4 A / cm².

[0060] La [Fig.4a] illustre un troisième exemple de configuration de la cellule electrochemical, in which the glass (E4) is directly integrated onto the cathode in the form of a solid cylinder 2 cm in diameter and 3 cm high. The anode (A1) forms a cylinder approximately 5 cm in diameter and 2 cm high, the volume of which The internal structure is at least partially completed with a mixture of lithium and potassium carbonates, Li₂CO₃-K₂CO₃ (eutectic), which acts as the CTA (Cold Transfer Agent). Figure 4b shows the values ​​of the temperature, the potential between the anode and the cathode, and the current density over a 30-minute period. The current density is gradually increased while the voltage stabilizes between 20 and 30 V. Oscillations in the current density are observable and are due to the accumulation of gas under the glass cylinder produced on the anode. A maximum current density of approximately 1 A / cm² is reached during the test.

[0061] Durant les deux essais présentés dans les [Fig.3a], 3b, 4a et 4b, la température deThe cell temperature does not exceed 780°C, which is below the vaporization temperature of metallic sodium and the melting point of glass. A metallic deposit was visually observed between the cathode and the glass, the composition of which is a ternary mixture of the metal oxides that make up glass, namely sodium, calcium, and silicon in their metallic forms. The experiments thus proved that it is possible to reduce metal oxides to a vitrified form below the melting point (T m ) and with the addition of a CTA anionic transport layer.

[0062] Enfin, la [Fig.5] représente le courant en fonction de la tension appliqué aux bornesElectrodes with vitrified regolith, in the unusual shape of a round bar 1 cm in diameter and 2 cm high, resting on a graphite cathode, were used. Two cell tests were performed with the regolith: for the first test, the CTA took the form of a layer of CaCl2, and for the second, liquid silver. These configurations were tested between 800 and 950°C. In both cases, a relatively stable current could be measured through the round regolith bar at a temperature below its melting point (Tmelting). m ) of the regolith, which validates the technique implemented and the purpose of the disclosure.

[0063] Ces différents exemples de réalisation permettent de définir que la température Tσ à at which ionic conduction begins is lower than the melting temperature T mGlass. This can be used to reduce glass to a lower temperature than traditional methods without emitting carbon dioxide. This technique can be implemented on a wide variety of available glass (TiO2, Fe2O3, amorphous regolith, etc.). This is made possible by the anionic transport layer (ATL). This technology is not directly or indirectly dependent on gravity when the ATL is solid and can be used to produce deoxygenated materials for space programs.

[0064] Un procédé simple de mis en œuvre pour produire de tels matériaux est le suivant,As shown in Figure 6.a. with a liquid ATC and Figure 6.b. with a solid ATC: – The cell is prepared, according to the specific design, to accommodate the selected glass; – The selected glass is inserted into the cell; – Then an ATC is added at the interface between the anode A1 and the glass; – The cell is then hermetically sealed and the heating means M3 are activated until a temperature between T is reached g and T menabling the redox processes; –A current setpoint is applied across the electrodes using a current generator. The current density is selected to initiate the redox processes without damaging the CTA or the anode. The current generator adjusts to apply an appropriate voltage to obtain the desired current density. –Once the system is stable, electrolysis at a specific current can be performed. The duration depends on the quantity of material to be reduced. For example, a volume of 1 cm³ of soda-lime glass (SLG) is completely reduced in 9 hours of electrolysis at a density of 0.5 A / cm² and a potential of 2 to 50 V, generating approximately 1 liter of pure oxygen under standard conditions. The glass reduction occurs at the cathode, while the gases from the oxidation reaction are produced at the anode.–Once the required amount of material to be reduced has been reached, the system is stopped and the result of the process is collected and cooled outside the cell. The AHU is recycled.

[0065] Des variantes de procédé peuvent être envisagées avec par exemple un procédé continuous extraction of materials in their reduced form. In this case, a high-temperature zone is required to melt the metal oxides above their melting point T m The reaction at the cathode occurs below the melting point T m and the glass transition temperature T g The reaction at the anode can be carried out here above or below the melting point T m with respectively an inert anode for high temperatures or a CTA combined with a low temperature inert anode.

[0066] Aussi, si les propriétés de l’anode le permettent, l’anode peut être directement prepared on the solid electrolyte (E4) with for example the sintering of porous materials allowing the evacuation of the gaseous phase generated between the solid electrolyte and the anode.

[0067] Enfin dans le cas d’un système fonctionnant sous vide, la réaction d’oxydationcan be further driven by the thermionic effect. The thermionic effect is the emission of electrons in a vacuum from the surface of materials with the increase in temperature. The emission of electrons J is described by the Richardson equation:

[0068] J=A 2 GT exp(-Ф / kbT)

[0069] avec T la température du métal en Kelvin, Ф la fonction de travail du métal, kb la Boltzmann constant and A G Richardson's constant.

[0070] La cellule objet de la divulgation trouve un intérêt particulier dans le cadre de laImplementation of carbon-free metal production at reasonable temperatures, requiring reduced electrical heating power. Indeed, the configuration proposed in the prototype demonstrates that the electrical power required for cell operation is compatible with power sources such as photovoltaic panels or individual wind turbines. Such photovoltaic panels can be installed in uncontrolled environments. The main advantage, therefore, lies in the fact that a system comprising multiple photovoltaic panels or other means of green electricity generation can be connected to one or more cells to generate metals and oxygen, which, if necessary, is stored in a specially designed tank.This oxygen is then used as a reserve for the production of other elements, or for consumption (for example in the context of an ambient air recycling system).

[0071] Dans d'autres situations, la mise en œuvre de la solution décrite dans le cadre de la This process can be carried out in dedicated industrial facilities. In this case, the cell dimensions are modified, notably to allow them to produce larger quantities of oxygen and metals. The cells can be connected in series or in parallel. The objective of this implementation is to promote the use of non-carbon-based electricity to facilitate metal reduction.

[0072] Dans le cadre d’une mise en œuvre sur le sol lunaire, la cellule peut également être powered by a locally produced energy source designed for the space environment.

Claims

AMENDED CLAIMS received by the International Bureau on November 30, 2025 (30.11.2025) 1. Electrochemical cell (ECC) comprising a chamber (EO) for the electrolysis of a solid inorganic electrolyte (E4) within which are positioned: - a first electrode (A1), - a second electrode (C2), - an anionic transport layer (ATL), - a solid inorganic electrolyte (E4), - and heating means (MC3) configured to deliver a temperature between 200°C and 1500°C, characterized in that: - the electrolyte (E4) is a solid inorganic material at room temperature, consisting of anions and cations, the anions oxide (O 2- representing more than 90 % of the total molar concentration of anions, -the CTA is an inorganic material whose properties allow the transport of anions from the electrolyte (E4) to the electrode (A1) so that there is no accumulation of gas phase in the vicinity of the electrode (A1). - the anionic transport layer (CTA) is arranged so as to be in direct contact only with the first electrode (A1) and with the electrolyte (E4), but not to be simultaneously in direct contact with both electrodes (A1, C2), - and the electrolyte (E4) is arranged so as to be in direct contact only with the second electrode (C2) and with the anionic transport layer (CTA), but not simultaneously in direct contact with both electrodes (A1, C2).

2. Cell according to claim 1, in which the electrolyte (E4) has a glass transition temperature (T g lower than its melting point (T m ), the operating temperature being between Tg and T m and the temperature range [T g ;T m ] is between 200°C and 1500°C.

3. Cell according to any one of claims 1 or 2, wherein the electrolyte (E4) is selected from: - soda-lime glass, borosilicate glass, or molten silica, - a material obtained from the vitrification of a mixture of metallic oxides, - a material obtained from the vitrification of regolith.

4. Cell according to any one of claims 1 to 3, wherein the anion transport layer (ATL) is a liquid metallic phase based on a metal belonging to column 11 of the periodic table of elements, said phase being electrochemically reactive and forming the site of the oxidation reactions of the anions from the electrolyte (E4), while ensuring electronic continuity between these reactions and a solid electrode (A1).

5. Cell according to any one of claims 1 to 3, wherein the anion transport layer (CTA) is not in direct contact with the electrode (C2) which acts as the cathode and transports the anions from the electrolyte (E4) to the electrode (A1) which acts as the anode, allowing the oxidation reaction of the anions on the electrode A1 by preventing the accumulation of a gaseous phase on its surface.

6. Cell according to claim 5, wherein the anionic transport layer (CTA) is an electrolyte selected from molten salts and eutectic molten salts.

7. Cell according to claim 5, wherein the anion transport layer (CTA) is an electrolyte selected from solid anion-conducting membranes 8. A method for the direct reduction of an inorganic electrolyte (E4) in an electrochemical cell (ECC) according to any one of claims 1 to 7, wherein the electrolyte E4 is a solid inorganic material at room temperature, all of whose cations are reduced to metallic form at electrode (C2) and all of whose anions are extracted using the CTA and transformed into gaseous form in the vicinity of electrode (A1) at an operating temperature between 200 and 1500°C, and more precisely at an operating temperature between the glass transition temperature (T g ) and the melting temperature (T m ) of the electrolyte (E4).

9. A method according to claim 2, comprising: - the insertion of the electrolyte (E4) in solid form into the cell (CEL); - the addition of the anionic transport layer (CTA) at the interface between the first electrode (A1) and the electrolyte (E4); -A step of hermetically sealing the electrochemical cell (ECC); - heating using the means (MC3) until the temperature is between the glass transition temperature (T g ) and the melting temperature (T m ) of electrolyte E4; - and the application of a potential sufficient to initiate the redox reactions at the electrodes (A1, C2).

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