seal for an electrochemical device, preferably a fuel cell or an electrolyser

Abstract

The present invention relates to a composition, preferably in the form of a paste or a solid, comprising at least one inorganic material based on glass and / or glass-ceramic and at least one source of lanthanum, a seal for an electrochemical device obtained from said composition, a method for manufacturing said seal, the use of said seal in an electrochemical device, and an electrochemical device comprising at least said seal.

Description

Title of the invention: Seal for an electrochemical device, preferably a fuel cell or an electrolyzer

[0001] The present invention relates to a composition, preferably in the form of a paste or a solid, comprising at least one inorganic material based on glass and / or glass-ceramic and at least one source of lanthanum, a seal for an electrochemical device obtained from said composition, a method for manufacturing said seal, the use of said seal in an electrochemical device, and an electrochemical device comprising at least said seal.

[0002] The field of the invention is the field of electrochemical devices, preferably high temperature, and in particular solid oxide electrochemical devices such as solid oxide electrolysers, also known by the Anglicism "Solid Oxide Electrolyser Cell" (corresponding abbreviation "SOEC"), "High Temperature Electrolysis" (corresponding abbreviation "HTE"), or "High Temperature Steam Electrolysis" (corresponding abbreviation "HTSE") or solid oxide fuel cells, also known by the Anglicism "Solid Oxide Fuel Cell" (corresponding abbreviation "SOFC"). State of the art

[0003] An electrolyser generally comprises at least one cell containing two electrodes: an anode, a cathode, and an electrolyte interposed between the electrodes, at least a first and a second metal interconnector (also called interconnection plates or bipolar plates) arranged on either side of the cell. The cell defines a so-called anode compartment between the first interconnector and the anode, and a so-called cathode compartment between the second interconnector and the cathode. During the electrolysis of water, an electrolytic reaction makes it possible to decompose the water (H2O) into dioxygen (O2) and dihydrogen gas (H2) using an electric current. In particular, in the cathode compartment, electrons from a voltage source are supplied to the cathode (or hydrogen electrode) and allow the water vapor (H2O) distributed to the cathode to be reduced to dihydrogen (H2) and recovered.The resulting O2 ions migrate through the electrolyte, which conducts oxygen O2 ions between the cathode and anode at high temperatures of about 700°C. In the anode compartment, the oxygen O2 ions are oxidized at the anode (or air electrode or oxygen electrode) to oxygen (O2) molecules, and the resulting oxygen is recovered, possibly using a carrier gas such as nitrogen or air. The interconnectors. carry the current and distribute the gases (e.g. water vapor, and possibly the carrier gas) to the electrodes. They also ensure the junction between two adjacent cells. In an electrolyzer, several cells are generally assembled in series using interconnectors to form a stack of several cell-interconnection assembly units. The stacking of cells and interconnectors in contact with each other requires the use of electrically insulating gaskets, to ensure the seals between the anode and cathode compartments but also with the outside. These seals have the function of ensuring good electrical insulation and guaranteeing better recovery of the gases produced. In particular, they prevent a short circuit and / or gas leaks between the two anode and cathode compartments and to the outside.Such seals may be seals ensuring sealing between the two compartments of each cell, seals ensuring sealing between the inlet (water vapor) and outlet (dihydrogen) gas supplies, and / or seals ensuring sealing of the electrolyser with the outside.

[0004] In a fuel cell, the operation is reversed to produce an electric current and heat, being supplied with gaseous dihydrogen (H2) or natural gas (eg methane CH4), and gaseous dioxygen (O2) or air. The notation of the electrodes is also reversed, naming the dihydrogen electrode the anode and the dioxygen electrode the cathode.

[0005] Currently, the most widely used electrolysis cells comprise an electrolyte composed of solid oxide(s). These are referred to as solid oxide electrolysis cells. In particular, the electrolysis cells comprise an electrolyte based on yttrium-stabilized zirconium dioxide (YSZ); a porous cathode comprising yttrium-stabilized zirconium dioxide (YSZ), a mixture of nickel and yttrium-stabilized zirconium dioxide (YSZ), or a mixture of nickel and gadolinium-doped cerium dioxide (GDC); and a porous anode (oxygen electrode or air electrode) comprising a lanthanum-based oxide, such as lanthanum-strontium-cobalt ferrite (LSCF) or lanthanum-strontium-cobalt (LSC), optionally mixed with gadolinium-doped cerium dioxide (GDC). The interconnectors may be made of a metal alloy containing chromium. The joints may be made of glass or glass-ceramic.Composite seals based on glass and mica or glass and ceramic have also been proposed.

[0006] By way of example, application FR3014246 A1 describes the use of sealing means ensuring sealing between the two cathode and anode compartments of each cell, of sealing means ensuring sealing between the inlet and outlet gas feeds and of sealing means ensuring sealing of the device with the outside. These sealing means are filed on a porous support using a robot and a pneumatic syringe in the form of a glass paste comprising, for example, a glass powder of the "Schott GO 18-311" type mixed with an ethanol-type solvent and a terpineol-type binder). Then, the resulting paste is heated so that it melts and fills specific openings in the porous support to form watertight partitions. This solution is however not entirely satisfactory in that the sealing means obtained do not prove to be sufficiently resistant from a mechanical point of view, in particular due to the excessive fluidity of the glass, to be able to maintain the seal in the face of the imposed pressure differences.

[0007] There is therefore a need for seals for electrochemical devices, in particular for electrolysers and fuel cells, preferably operating at high temperatures, which are mechanically and / or thermomechanically strong. There is also a need for seals which can be prepared in a reliable, simple and reproducible manner.

[0008] The aim of the present invention is therefore to provide a seal with mechanically and / or thermomechanically improved properties.

[0009] Another aim of the present invention is to provide a method for manufacturing a seal that is simple to implement, reproducible and reliable. Statement of the invention

[0010] The first subject of the invention is a composition for a sealing joint, preferably in solid form or in the form of a paste, characterized in that it comprises at least one inorganic material chosen from glasses, glass-ceramics, glasses reinforced by ceramic particles, and one of their mixtures, and at least one source of lanthanum chosen from La, La2O3, La2Zr2O7, LaCrO3, LaFeO 3, and one of their mixtures.

[0011] Thanks to the combination of at least one inorganic material chosen from glasses, glass-ceramics, glasses reinforced by ceramic particles, and one of their mixtures, and at least one source of lanthanum chosen from La, La2O3, La2Zr2O7, LaCrO3, LaFeO3, and one of their mixtures, the intrinsic mechanical properties of the seal obtained from said composition are improved and / or the anchoring properties of the seal obtained from said composition within the electrochemical device are improved.

[0012] In the composition of the invention, the inorganic material is in particular in the form of solid particles, preferably of a size ranging from approximately 50 nm to 50 μm, and particularly preferably of a size ranging from approximately 500 nm to 10 μm.

[0013] In the composition of the invention, the source of lanthanum is in particular in the form of solid particles, preferably of a size ranging from approximately 50 nm to 50 pm. The size can be modulated depending on the role of the source of lanthanum. A source of reactive lanthanum, e.g., La or La2O3, ideally has a finer particle size, preferably from about 50 nm to 1 pm, and a source of lanthanum as a mechanical reinforcement, e.g., La2Zr2O7, LaCrO3, or LaFeO3, has a larger particle size, preferably from about 1 pm to 50 pm

[0014] The composition is preferably in solid form; or in the form of a paste (also called slip, mud, or slurry).

[0015] When the composition is in the form of a paste, it may further comprise at least one solvent, preferably chosen from water, alcohols, carbonates, ketones, and aromatic hydrocarbons.

[0016] Examples of alcohols that may be mentioned are C1-C5 alcohols such as methanol, ethanol, or propanol.

[0017] Examples of carbonates include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, or methyl and ethyl carbonate.

[0018] Examples of ketones include butanone.

[0019] Examples of aromatic hydrocarbons include toluene.

[0020] When the composition is in the form of a paste, it may further comprise at least one organic binder, preferably chosen from polyalcohols such as polyvinyl alcohol, polyesters such as poly(vinyl butyral), and celluloses.

[0021] When the composition is in the form of a paste, it may further comprise at least one dispersant, preferably chosen from vegetable oils such as corn oil and linseed oil, animal oils such as fish oils, fatty acids such as oleic acid, polyacids such as citric acid, and phosphoric acid diesters.

[0022] The composition in the form of a paste preferably comprises from 60% to 98% by mass approximately of lanthanum source(s) and inorganic material, relative to the total mass of the composition.

[0023] When the composition is in solid form, it is preferably in powder form, i.e. in the form of a powder.

[0024] According to a first preferred embodiment of the invention, the source of lanthanum is La2Zr2O7, optionally mixed with at least one other source of lanthanum.

[0025] This thus makes it possible to improve the mechanical strength of the seal. La2Zr2O7 in particular ensures the role of mechanical reinforcement of the seal.

[0026] In this first embodiment, La2Zr2O7 preferably represents at least approximately 15% by mass, and particularly preferably from approximately 40% to 95% by mass, relative to the total mass of the inorganic material and of the lanthanum source(s) in the composition.

[0027] According to a second preferred embodiment of the invention, the source of lanthanum is La2O3, optionally mixed with at least one other source of lanthanum.

[0028] This thus makes it possible to ensure the anchoring of the seal within the electrochemical device. In particular, La2O3 has a surface reactivity which allows the creation of interface layers with one or more elements of the electrochemical device.

[0029] In this second embodiment, La2O3 preferably represents at least approximately 0.1% by mass, and particularly preferably from approximately 0.5% to 10% by mass, relative to the total mass of the inorganic material and of the lanthanum source(s) in the composition.

[0030] According to a third preferred embodiment of the invention, the source of lanthanum is LaCrO3 or LaFeO3, optionally mixed with at least one other source of lanthanum.

[0031] This thus makes it possible to improve the mechanical strength of the seal. LaCrO3 or LaFeO3 in particular ensures the role of mechanical reinforcement of the seal.

[0032] In this third embodiment, LaCrO3 preferably represents at least approximately 15% by mass, and particularly preferably from approximately 40% to 95% by mass, relative to the total mass of the inorganic material and of the lanthanum source(s) in the composition.

[0033] In this third embodiment, LaFeO3 preferably represents at least approximately 15% by mass, and particularly preferably from approximately 40% to 95% by mass, relative to the total mass of the inorganic material and lanthanum source(s) in the composition.

[0034] When the composition comprises La as a source of lanthanum, this represents at most approximately 5% by mass, and particularly preferably from 0.01% to approximately 4% by mass, relative to the total mass of the inorganic material and the source(s) of lanthanum in the composition.

[0035] The (as a source of lanthanum) makes it possible to ensure the anchoring of the sealing gasket within the electrochemical device.

[0036] According to a preferred embodiment of the invention, the composition comprises at least La2O3 in combination with La2Zr2O7, LaCrO3, or LaFeO3, as sources of lanthanum. This thus makes it possible to ensure both good mechanical strength and good anchoring within the electrochemical device.

[0037] The contents of La2Zr2O7, LaCrO3, LaFeO3, and La2O3 in said composition may be such as those described in the first, second and third embodiments above.

[0038] The composition may further comprise La. This thus makes it possible to further improve the anchoring of the seal within the electrochemical device.

[0039] The La content in said composition may be as described above.

[0040] According to a particularly preferred embodiment of the invention, the composition comprises at least La2O3 in combination with La2Zr2O7, as sources of lanthanum.

[0041] The composition of the invention comprises at least one inorganic material chosen from glasses, glass-ceramics, glasses reinforced by ceramic particles, and one of their mixtures.

[0042] Examples of glass-ceramics include glass-ceramics marketed by Schott, in particular the “G018” range.

[0043] Examples of glasses include those marketed by Corning such as “Corning 0080” glass.

[0044] The inorganic material preferably has a coefficient of thermal expansion ranging from approximately 5 x 106 to 15 x 106 K1 (20°C, 300°C).

[0045] Said inorganic material may have a glass transition temperature less than or equal to the operating temperature of the electrochemical device.

[0046] The operating temperature of the electrochemical device, in particular of the electrolyser type operating at high temperature, generally ranges from approximately 600 to 1000°C, and preferably from approximately 600 to 800°C.

[0047] Preferably, said inorganic material has a glass transition temperature less than or equal to approximately 700°C, particularly preferably less than or equal to approximately 650°C, and more particularly preferably less than or equal to approximately 600°C.

[0048] The composition of the invention may be prepared by mixing the lanthanum source(s) with the inorganic material to form a resulting powder. The resulting powder may undergo a heat treatment (calcination, pre-sintering) and / or may be ground. The grinding makes it possible in particular to obtain a homogeneous powder composition with the desired particle size. The heat treatment makes it possible to adjust the microstructure and / or to give it sufficient mechanical strength for handling before the heat treatment which makes it possible to form the joint and which will ensure the establishment of the seal.

[0049] Alternatively, the composition may be prepared by mixing the lanthanum source(s), the inorganic material, optionally at least one solvent, optionally a dispersant, and optionally an organic binder. This thus makes it possible to form a slip or an ink (also called a paste).

[0050] Other additives may be added such as a plasticizer or any other ingredient allowing the pasty consistency of the composition to be adjusted.

[0051] The composition may have a dynamic viscosity ranging from approximately 1 to 15 Pa.s. Viscosity can be measured using a rotational viscometer with variable speeds, for example using a Brookfield type viscometer having 3 or 4 spindles and a rotation speed ranging from about 12 to 60 revolutions per minute.

[0052] The second subject of the invention is a seal for an electrochemical device, characterized in that it is obtained by heat treatment of a composition in accordance with the first subject of the invention at a temperature above a glass transition temperature of the inorganic material.

[0053] Consequently, when the composition in accordance with the first subject of the invention is heat-treated at a temperature above a glass transition temperature of said inorganic material, this results in a seal which makes it possible to ensure sealing in the electrochemical device.

[0054] The heat treatment temperature may be the operating temperature of said electrochemical device, preferably a temperature greater than approximately 600°C, particularly preferably greater than approximately 650°C, and more particularly preferably greater than approximately 700°C.

[0055] The heat treatment temperature may be at most 1000°C.

[0056] The heat treatment preferably lasts at least approximately 30 min, and particularly preferably approximately 1 to 5 hours.

[0057] The seal is preferably obtained in situ during the first operation of said electrochemical device.

[0058] The difference between the heat treatment temperature and the glass transition temperature of the inorganic material is preferably at least 30°C, and even more preferably at least 50°C.

[0059] Before reaching the heat treatment temperature, a temperature rise from room temperature (18-25°C) to the heat treatment temperature at a rate of approximately 0.1 to 10°C per minute, and preferably approximately 1 to 5°C per minute, may be implemented. This temperature rise is particularly suitable when the composition is in the form of a paste. This temperature rise may in particular make it possible to optionally remove the solvent, optionally the organic binder, optionally the dispersant and / or optionally any of the aforementioned additives.

[0060] A temperature stage ranging from approximately 350 to 450°C may be added during which the temperature rise is stopped, preferably for at least approximately 30 min, and particularly preferably for a period ranging from approximately 45 min to 2 h. This stage is particularly suitable when the composition is in the form of a paste. This thus makes it possible to optionally eliminate the solvent, optionally the organic binder, optionally the dispersant and / or optionally any aforementioned additive.

[0061] The third subject of the invention is a method for manufacturing a seal for an electrochemical device, characterized in that it comprises at least one step i) of applying a composition conforming to the first subject to a support, then a step ii) of heat treatment at a temperature above a glass transition temperature of the inorganic material.

[0062] Step i)

[0063] Step i) may be carried out by casting the composition onto said support or by extruding the composition onto said support.

[0064] The casting step is preferably carried out by strip casting.

[0065] The casting step is particularly suitable when the composition is in the form of a paste.

[0066] The extrusion step is preferably carried out using a controlled deposition device.

[0067] The extrusion step is particularly suitable when the composition is in solid form.

[0068] Application step i) may be followed by a drying step i-1). Drying may in particular allow the solvent to be evaporated if it is present in the composition.

[0069] At the end of the drying step after casting, the dried composition may undergo a shaping step such as cutting (for example cutting with a die, knife, or laser), calendering, heat pressing and / or rolling.

[0070] The extrusion step can be carried out using a syringe, for example by extruding the composition in the form of a bead.

[0071] The support can be any type of support, and preferably a support made of metal, inorganic material of the ceramic or mineral type, or non-stick material, for example of the “Mylar” type.

[0072] Step ii)

[0073] Heat treatment ii) is as defined in the second subject of the invention.

[0074] Step ii) is preferably carried out on the composition in situ during the first operation of said electrochemical device.

[0075] Step i')

[0076] Between steps i) and ii), the method may comprise a step i') during which a temperature is raised from room temperature (18-25°C) to the heat treatment temperature of step ii) at a rate of approximately 0.1 to 10°C per minute, and preferably approximately 1 to 5°C per minute, in order to reach the heat treatment temperature as defined in the invention. This temperature increase is particularly suitable when the composition is in the form of a paste. This rise in temperature can in particular make it possible to possibly eliminate the solvent, possibly the organic binder, possibly the dispersant and / or possibly any of the aforementioned additives.

[0077] Step i') may also comprise a hold at a temperature ranging from approximately 350 to 450°C during which the temperature rise is stopped, preferably for at least approximately 30 min, and particularly preferably for a period ranging from approximately 45 min to 2 h. This hold is particularly suitable when the composition is in the form of a paste. This thus makes it possible to optionally eliminate the solvent, optionally the organic binder, optionally the dispersant and / or optionally any of the aforementioned additives.

[0078] Step i') makes it possible in particular to eliminate all the ingredients used to form a composition in the form of a paste. At the end of step i'), the composition is then in particular a solid composition comprising the inorganic material and the source(s) of lanthanum.

[0079] Step iii)

[0080] The method may further comprise a step iii) of cooling.

[0081] Cooling step iii) may be carried out so as to pass from the temperature heat treatment as defined in the second subject of the invention or in the third subject for step ii) at a temperature lower than said heat treatment temperature and higher than the glass transition temperature of the inorganic material.

[0082] Step iO)

[0083] The method according to the third subject of the invention may comprise, before step i), a step iO) of mixing at least one inorganic material chosen from glasses, glass-ceramics, glasses reinforced by ceramic particles, and one of their mixtures, with at least one source of lanthanum chosen from La, La2O3, La2Zr2 O7, LaCrO3, LaFeO3, and one of their mixtures, to form a composition, preferably in solid form or in the form of a paste.

[0084] The composition of the invention can be prepared by solid or liquid means as described in the first subject of the invention.

[0085] In particular, a powder of at least one source of lanthanum may be mixed with a powder of inorganic material to form a resulting powder. The resulting powder may undergo a heat treatment (calcination, pre-sintering) and / or may be ground. The grinding makes it possible in particular to obtain a homogeneous powder composition with the desired particle size. The heat treatment makes it possible to adjust the microstructure and / or to give it sufficient mechanical strength for handling before the heat treatment which makes it possible to form the seal and which will ensure the establishment of the seal.

[0086] Alternatively, the composition may be prepared by mixing said at least one source of lanthanum, the inorganic material, optionally at least one solvent, optionally a dispersant, and optionally an organic binder.

[0087] Other additives may be added such as a plasticizer or any other ingredient allowing the pasty consistency of the composition to be adjusted.

[0088] On-site manufacturing

[0089] Step ii) is preferably carried out in situ, e.g. during operation of the device. The composition is then preferably placed within the electrochemical device before step ii). Step i) can be implemented either by direct application of the composition to at least one part of said electrochemical device (the support is then a part of an electrochemical device), or by application of the composition to a support external to the electrochemical device, then transfer of the composition from said external support to at least one part of said electrochemical device.

[0090] The external support may be made of non-stick material, for example of the “Mylar” type. The support as a part of said electrochemical device may be a support made of metal or of an inorganic material of the ceramic or mineral type.

[0091] In this in situ manufacturing embodiment, step i) preferably comprises bringing the composition in accordance with the first subject of the invention into contact with at least two parts of an electrochemical device, to form a part / composition / part assembly.

[0092] Step i) can then be carried out by casting the composition onto at least one of the two parts or onto a contact element between the two parts; or by extruding the composition onto at least one of the two parts or onto a contact element between the two parts.

[0093] At the end of step i), or at least before step ii), the composition is placed in abutment against the two parts.

[0094] Step ii) is then a step of heat treatment of the part / composition / part assembly at a temperature above a glass transition temperature of the inorganic material, to form a seal placed between the two parts.

[0095] The heat treatment is as defined in the second subject of the invention and in the third subject of the invention (step ii)).

[0096] During the process of the invention, the composition in accordance with the first subject of the invention is heat-treated at a temperature above a glass transition temperature of said inorganic material, this leads to a joint which makes it possible to ensure sealing in the electrochemical device, and in particular between the two parts.

[0097] The two parts can be two interconnectors on either side of a cell, an interconnector and a cathode of the same cathode compartment, or an interconnector and an electrolyte of the same anode compartment.

[0098] In the invention, the electrolyte is preferably a solid electrolyte.

[0099] The electrolyte preferably comprises zirconium, and particularly preferably comprises YSZ.

[0100] The interconnectors each preferably comprise chromium and / or iron.

[0101] According to a preferred embodiment of the invention, the source of lanthanum in the composition is adapted to at least one of the two parts, according to one of the following alternatives: - the composition comprises at least La2Zr2O7, and preferably at least La2Zr2O7 in combination with La2O3, and one of the two parts is an electrolyte, preferably comprising zirconium, - the composition comprises at least LaCrO3, and preferably at least LaCrO3 in combination with La2O3, and at least one of the two parts is an interconnector, preferably comprising chromium, - the composition comprises at least LaFeO3 and preferably at least LaFeO3 in combination with La2O3, and at least one of the two parts is an interconnector, preferably comprising iron, - the composition comprises at least LaCrO3 and LaFeO3 and preferably at least LaCrO3 and LaFeO3 in combination with La2O3, and at least one of the two parts is an interconnector, preferably comprising iron and chromium

[0102] The fourth object of the invention is the use of a seal in accordance with the second object of the invention or manufactured according to a method in accordance with the third object of the invention, in an electrochemical device, preferably in a fuel cell or an electrolyser.

[0103] The seal of the invention can be used in an electrochemical device such as a fuel cell or an electrolyser, preferably operating at high temperature, particularly preferably in a fuel cell or a solid oxide electrolyser, and more particularly preferably in a solid oxide electrolyser.

[0104] Thanks to the seal of the invention, the seals are more robust from a mechanical and thermomechanical point of view, which makes it possible to improve the electrochemical performance of said device and to avoid short circuits.

[0105] The fifth subject of the invention is an electrochemical device such as a fuel cell or an electrolyser, preferably operating at high temperature, particularly preferably a fuel cell or a solid oxide electrolyser, and more particularly preferably a solid oxide electrolyser, including: - at least one elementary cell containing an anode, a cathode, and an electrolyte interposed between the anode and the cathode, - at least one first and one second interconnector arranged on either side of the elementary cell, the elementary cell defining an anode compartment between the anode and the first interconnector, and the elementary cell defining a cathode compartment between the cathode and the second interconnector, and - at least one seal, characterized in that the seal is in accordance with the second object of the invention or manufactured according to a method in accordance with the third object of the invention.

[0106] The electrochemical device comprises at least one seal, and preferably several seals in accordance with the second subject of the invention or manufactured according to a method in accordance with the third subject of the invention.

[0107] These seals have improved mechanical strength and thus make it possible to improve the service life of the electrochemical device.

[0108] According to a preferred embodiment, the seal is placed in abutment against the first interconnector and the electrolyte, in abutment against the first and second interconnectors, or in abutment against the second interconnector and the cathode, and preferably in abutment against the first interconnector and the electrolyte.

[0109] Depending on the position of the seal in the device, its composition, and in particular the source of lanthanum used, can be adapted so as to optimize its mechanical and thermomechanical properties.

[0110] According to a particularly preferred embodiment, the electrochemical device comprises: - at least one first sealing gasket placed in abutment against the first interconnector and the electrolyte, - at least one second seal placed in abutment against the first and second interconnectors, and - at least a third seal placed in abutment against the second interconnector and the cathode, at least one of said first, second, or third seals being in accordance with the second subject of the invention or manufactured according to a method in accordance with the third subject of the invention, and preferably said first, second, and third seals being in accordance with the second subject of the invention or manufactured according to a method in accordance with the third subject of the invention.

[0111] The first seals are preferably located at the periphery of air supply and oxygen recovery ducts produced.

[0112] The third seals are preferably located at the periphery of water vapor supply and hydrogen recovery pipes produced.

[0113] The electrolyte preferably comprises zirconium, and particularly preferably comprises YSZ.

[0114] The first interconnector preferably comprises chromium and / or iron.

[0115] The second interconnector preferably comprises chromium and / or iron.

[0116] The first seal is preferably obtained from a composition in accordance with the first subject of the invention comprising one or more sources of lanthanum chosen from La2Zr2O7, LaCrO3, and LaFeO3, optionally in combination with La2O3 and / or La. The combination with La2O3 is more particularly preferred so as to have a homogeneous joint-interface junction.

[0117] The second seal is preferably obtained from a composition in accordance with the first subject of the invention comprising one or more sources of lanthanum chosen from LaCrO3 and LaFeO3, more preferably in combination with La2O3 and / or La. The combination with La2O3 is more particularly preferred so as to have a homogeneous seal-interface junction.

[0118] The third seal is preferably obtained from a composition in accordance with the first subject of the invention comprising one or more sources of lanthanum chosen from LaCrO3 and LaFeO3, more preferably in combination with La2O3 and / or La. The combination with La2O3 is more particularly preferred so as to have a homogeneous seal-interface junction.

[0119] According to a preferred embodiment of the invention, the device further comprises one or more interface layers formed by heat treatment of said seal at a temperature above a glass transition temperature of the inorganic material, and any one of the first interconnector, electrolyte, or second interconnector comprises at least one metallic element capable of reacting with at least one source of lanthanum of said seal (or of said composition from which it is derived) during said heat treatment.

[0120] Interface layers can thus form in situ between the seal and at least one of the parts of the device. This thus makes it possible to promote the anchoring of the seal within the electrochemical device.

[0121] The source of lanthanum is preferably La2O3 or La, and particularly preferably La2O3 optionally in combination with La.

[0122] The metallic element is preferably chosen from Cr, Zr, and Fe.

[0123] The heat treatment temperature may be the operating temperature of said electrochemical device, preferably a temperature greater than approximately 600°C, particularly preferably greater than approximately 650°C, more particularly preferably greater than approximately 700°C, and even more particularly preferably greater than approximately 750°C.

[0124] The heat treatment temperature may be at most approximately 1000°C.

[0125] The heat treatment preferably lasts at least approximately 30 min, and particularly preferably approximately 1 to 5 hours.

[0126] In particular, the electrochemical device comprises at least any one of the following interface layers: - at least one interface layer formed by heat treatment of a first seal as defined above, said interface layer being placed in abutment against said first seal and the electrolyte, said lanthanum source comprising at least La2Zr2O7 in combination with La2O3, - at least one interface layer formed by heat treatment of a first seal as defined above, said interface layer being placed in abutment against said first seal and the first interconnector, said lanthanum source comprising at least LaCrO3 and / or LaFeO3, in combination with La2O3, - at least one interface layer formed by heat treatment of a second seal as defined above, said interface layer being placed in abutment against said second seal and the first interconnector, said lanthanum source comprising at least LaCrO3 and / or LaFeO3, in combination with La2O3, - at least one interface layer formed by heat treatment of a second seal as defined above, said interface layer being placed in abutment against said second seal and the second interconnector, said lanthanum source comprising at least LaCrO3 and / or LaFeO3, in combination with La2O3, - at least one interface layer formed by heat treatment of a third seal as defined above, said interface layer being placed in abutment against said third seal and the second interconnector, said lanthanum source comprising at least LaCrO3 and / or LaFeO3, in combination with La2O3. Description of figures and examples

[0127] Other advantages and characteristics will appear on examining the detailed description of non-limiting embodiments, and the appended drawings in which: [Fig.l] [Fig.l] is a schematic representation of a first example of embodiment of the device according to the fifth object of the invention; [Fig.2] [Fig.2] is a schematic representation of a second exemplary embodiment of the device according to the fifth object of the invention.

[0128] It is understood that the embodiments which will be described below are in no way limiting. In particular, variants of the invention may be imagined. comprising only a selection of features described subsequently, isolated from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art. This selection includes at least one preferably functional feature without structural detail, or with only a part of the structural details if this part is only sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art.

[0129] In the figures, the elements common to several figures retain the same reference.

[0130] [Fig.l] represents an electrochemical device 1 according to the invention, such as a solid oxide electrolyser comprising: - at least one elementary cell 2 containing a porous anode 3 (oxygen electrode or air electrode) comprising for example a lanthanum-based oxide, such as lanthanum-strontium-cobalt ferrite (LSCF) or lanthanum-strontium-cobalt (LSC), optionally mixed with gadolinium-doped cerium dioxide (GDC); a porous cathode 4 comprising for example yttrium-stabilized zirconium dioxide (YSZ), a mixture of nickel and yttrium-stabilized zirconium dioxide (YSZ), or a mixture of nickel and gadolinium-doped cerium dioxide (GDC); and an electrolyte 5 for example based on yttrium-stabilized zirconium dioxide (YSZ). Said electrolyte is in particular interposed between the anode and the cathode. - at least a first interconnector 6 and a second interconnector 7 arranged on either side of the elementary cell 2, the elementary cell 2 defining an anode compartment 8 between the anode 3 and the first interconnector 6, and the elementary cell 2 defining a cathode compartment 9 between the cathode 4 and the second interconnector 7.

[0131] The electrochemical device comprises: - at least one first seal (10a, 10b) placed in abutment against the first interconnector 6 and the electrolyte 5, - at least one second seal (11a, 11b) placed in abutment against the first and second interconnectors (6, 7), and - at least one third seal (12a, 12b) placed in abutment against the second interconnector 7 and the cathode 4, at least one of said first, second, or third seals being in accordance with the second subject of the invention or manufactured according to a method in accordance with the third subject of the invention, and preferably said first, second, or third seals being in accordance with the second subject of the invention or manufactured according to a method in accordance with the third object of the invention.

[0132] Preferably, the first seal (10a, 10b) is obtained from a composition in accordance with the first subject of the invention comprising one or more sources of lanthanum chosen from La2Zr2O7, LaCrO3, and LaFeO3, optionally in combination with La2O3 and / or La.

[0133] Preferably, the second seal (11a, 11b) is preferentially obtained from a composition in accordance with the first subject of the invention comprising one or more sources of lanthanum chosen from LaCrO3 and LaFeO3, more preferentially in combination with La2O3 and / or La.

[0134] Preferably, the third seal (12a, 12b) is preferentially obtained from a composition in accordance with the first subject of the invention comprising one or more sources of lanthanum chosen from LaCrO3 and LaFeO3, more preferentially in combination with La2O3 and / or La

[0135] In [Fig. 1], the entry of water vapor into the cathode compartment 9 and the exit of dihydrogen from the cathode compartment 9 can be visualized. The entry of air into the anode compartment 8 and the exit of air and dioxygen from the anode compartment 8 can be visualized.

[0136] The first sealing joints (10a, 10b) are preferably located at the end network of air supply and oxygen recovery ducts produced (ducts not shown).

[0137] The third seals (12a, 12b) are preferably located at the periphery of conduits for supplying water vapor and recovering the dihydrogen produced (conduits not shown).

[0138] [Fig.2] represents an electrochemical device 100 according to the invention, such that a solid oxide electrolyzer having the same characteristics as described above for device 1, except that device 100 further comprises one or more interface layers.

[0139] In particular, the electrochemical device 100 comprises at least any one of the following interface layers: - at least one interface layer (102a, 102b) formed by heat treatment of a first seal as defined above (10a, 10b), said interface layer being placed in abutment against said first seal (10a, 10b) and the electrolyte 5, said lanthanum source comprising at least La2Zr2O7 in combination with La2O3, - at least one interface layer (101a, 101b) formed by heat treatment of a first seal as defined above (10a, 10b), said interface layer (101a, 101b) being placed in abutment against said first seal (10a, 10b) and the first interconnector 6, said lanthanum source comprising at least less LaCrO3 and / or LaFeO3, in combination with La2O3, - at least one interface layer (111a, 111b) formed by heat treatment of a second seal as defined above (11a, 11b), said interface layer (111a, 111b) being placed in abutment against said second seal (11a, 11b) and the first interconnector 6, said lanthanum source comprising at least LaCrO3 and / or LaFeO3, in combination with La2O3, - at least one interface layer (112a, 112b) formed by heat treatment of a second seal as defined above (11a, 11b), said interface layer (112a, 112b) being placed in abutment against said second seal (11a, 11b) and the second interconnector 7, said lanthanum source comprising at least LaCrO3 and / or LaFeO3, in combination with La2O3, - at least one interface layer (121a, 121b) formed by heat treatment of a third seal as defined above (12a, 12b), said interface layer (121a, 121b) being placed in abutment against said third seal and the second interconnector 7, said lanthanum source comprising at least LaCrO3 and / or LaFeO3, in combination with La2O3.

[0140] Example 1: manufacturing a seal in accordance with the second subject of the invention or manufactured according to a method in accordance with the third subject of the invention

[0141] A composition in accordance with the invention was prepared in the form of a paste comprising 39% by mass of La2Zr2O7, 38% by mass of an inorganic material sold under the reference “Schott G018-311” (glass ceramic), 8% by mass of ethanol and 8% by mass of methyl and ethyl carbonate as solvents, 1% by mass of a dispersant of the phosphoric acid diester type (“CP213”), 4% by mass of an organic binder of the poly(vinyl butyral) type, and 2% by mass of a plasticizer of the polyethylene glycol type (“PEG 400”).

[0142] This composition was applied to a support by tape casting. In particular, the composition was placed in a casting tank, then cast onto a polyester support (e.g. “Mylar” type support) which moves continuously to allow tape application. The composition is left to air dry to remove the solvents and then the resulting tape is directly incorporated into an electrolyzer, for example pressing against the electrolyte and the first interconnector.

[0143] The seal is manufactured in situ by operating the electrolyser at a temperature of 700°C.

[0144] Example 2: manufacturing a seal in accordance with the second subject of the invention or manufactured according to a method in accordance with the third subject of the invention

[0145] A composition in accordance with the invention was prepared in the form of a paste comprising 70% by mass of La2Zr2O7, 1% by mass of La2O3, 7% by mass of an inorganic material (glass) sold under the reference “Corning 0080”, 8% by mass mass of ethanol and 8% by mass of methyl and ethyl carbonate as solvents, 1% by mass of a phosphoric acid diester type dispersant (“CP213”), 3% by mass of an organic binder of the poly(vinyl butyral) type, and 2% by mass of a polyethylene glycol type plasticizer (“PEG 400”).

[0146] This composition was applied to a support as described in Example 1. The composition is left to air dry and then the resulting strip is directly incorporated into an electrolyser, for example pressing against the electrolyte and the first interconnector.

[0147] The seal is manufactured in situ by operating the electrolyser at a temperature of 700°C.

[0148] An interface layer is also fabricated in situ in abutment against the seal and the electrolyte.

Claims

Claims

1. Composition for a seal, characterized in that it comprises at least one inorganic material chosen from glasses, glass-ceramics, glasses reinforced by ceramic particles, and one of their mixtures, and at least one source of lanthanum chosen from La, La2O3, La2Zr2O7, LaCrO3, LaFeO3, and one of their mixtures.

2. Composition according to claim 1, characterized in that it is in solid form or in the form of a paste.

3. Composition according to claim 1 or claim 2, characterized in that the source of lanthanum is La2O3, optionally mixed with at least one other source of lanthanum.

4. Composition according to any one of the preceding claims, characterized in that the source of lanthanum is La2Zr2O7, optionally mixed with at least one other source of lanthanum.

5. Composition according to any one of the preceding claims, characterized in that the source of lanthanum is LaCrO3 or LaFeO3, optionally mixed with at least one other source of lanthanum.

6. A composition according to any preceding claim, characterized in that the composition comprises at least La2O3 in combination with La2Zr2O7, LaCrO3, or LaFeO3, as sources of lanthanum.

7. Composition according to any one of the preceding claims, characterized in that said inorganic material has a glass transition temperature less than or equal to 700°C.

8. Seal for an electrochemical device, characterized in that it is obtained by heat treatment of a composition as defined in any one of the preceding claims at a temperature above a glass transition temperature of the inorganic material.

9. Method for manufacturing a seal for an electrochemical device, characterized in that it comprises at least one step i) of applying a composition as defined in any one of claims 1 to 7 to a support, then a step ii) of heat treatment at a temperature above a glass transition temperature of the inorganic material.

10. Method according to claim 9, characterized in that it comprises before step i), a step i0) of mixing at least one inorganic material selected from glasses, glass-ceramics, glasses reinforced with ceramic particles, and a mixture thereof, with at least one source of lanthanum selected from La, La2O3, La2Zr2O7, LaCrO3, LaFeO3, and a mixture thereof, to form a composition.

11. Method according to claim 9 or 10, characterized in that it comprises between steps i) and ii), a step i') during which a temperature is raised from room temperature to the heat treatment temperature of step ii) at a rate of 0.1 to 10°C per minute.

12. Use of a seal as defined in claim 8 or manufactured according to a method as defined in any one of claims 9 to 11, in an electrochemical device, preferably in a fuel cell or an electrolyser.

13. Electrochemical device, preferably a fuel cell or electrolyser, comprising: - at least one elementary cell containing an anode, a cathode, and an electrolyte interposed between the anode and the cathode, - at least one first and one second interconnector arranged on either side of the elementary cell, the elementary cell defining an anode compartment between the anode and the first interconnector, and the elementary cell defining a cathode compartment between the cathode and the second interconnector, and - at least one seal, characterized in that the seal is as defined in claim 8 or manufactured according to a method as defined in any one of claims 9 to 11.

14. Device according to claim 13, characterized in that the sealing gasket is placed in abutment against the first interconnector and the electrolyte, in abutment against the first and second interconnectors, or in abutment against the second interconnector and the cathode.

15. Device according to claim 13 or 14, characterized in that it further comprises one or more interface layers formed by heat treatment of said seal at a temperature above a glass transition temperature of the inorganic material, and any one of the first interconnector, electrolyte, or second interconnector comprises at least one metallic element capable of reacting with at least one source of lanthanum of said seal during said heat treatment.

Images