Spacer for a solid oxide electrochemical device, solid oxide electrochemical device comprising such a spacer, and solid oxide electrochemical system comprising such devices

Abstract

The invention relates to a spacer for a solid oxide electrochemical device (200), the device (200) comprising: - at least one interconnector (102, 104); - a solid oxide electrochemical cell (106) arranged between the interconnector (102, 104) and another interconnector (102, 104); and - the spacer (202), arranged between the interconnectors (102, 104), in particular around the cell (106); characterised in that the spacer (202): - comprises a layer, referred to as the main layer, made of an electrically insulating ceramic matrix composite material, referred to as a CMC material, or of a precursor of the CMC material; and - is partially or entirely gas-tight. The invention further relates to a solid oxide electrochemical device comprising such a spacer. The invention further relates to a solid oxide electrochemical system comprising such electrochemical devices.

Description

DESCRIPTION Title: Spacer for solid oxide electrochemical device, solid oxide electrochemical device comprising such a spacer, and solid oxide electrochemical system comprising such devices

[0001] The present invention relates to a spacer for a solid oxide electrochemical device. It also relates to a solid oxide electrochemical device comprising such a spacer. It further relates to a solid oxide electrochemical system comprising such devices.

[0002] The field of the invention is generally the field of solid oxide electrochemical systems, of the electrolyzer or fuel cell type. State of the art

[0003] A solid oxide electrochemical system, SEOS, of the electrolyzer or fuel cell type, comprises a stack of unit devices. Each unit device of the stack comprises an electrically conductive interconnector and a solid oxide electrochemical cell arranged between said interconnector and another interconnector, for example of an adjacent electrochemical device. It is necessary to ensure electrical continuity between each interconnector and the cell, while avoiding direct electrical contact between said two interconnectors so as not to short-circuit the electrochemical cell. In addition, it is necessary to ensure gas flow circulation between the cell and each interconnector, which requires gas sealing between the interconnectors, around the cell.

[0004] In operation, the stack is brought to a high operating temperature, for example between 600°C and 850°C in the case of a solid oxide electrolyser, SOE. Therefore, it is necessary that the parts making up the SEOS are resistant to these temperatures and have similar expansion behaviors under penalty of degrading the SEOS. In addition, the SEOS operates in an oxido-reducing and humid atmosphere, which requires chemical compatibility of the parts that compose it.

[0005] Due to these constraints, in current architectures, electrical insulation is provided by an electrical insulation layer placed between the interconnectors, which is generally made of a mica-based material. However, the insulation layer made of mica is mechanically fragile, making it difficult to manufacture and handle, particularly when it is put under pressure during use of the stack, for example in the case of solid oxide electrolysers.

[0006] In some embodiments, gas sealing may be ensured by a multitude of sealing beads, generally made of glass, deposited between the parts forming the electrochemical device. The deposition of these sealing beads is time-consuming, making the manufacturing of the SEOS time-consuming and costly. In addition, a defect in these sealing beads will have significant consequences on the performance of the SEOS, or may even lead to degradation of the SEOS.

[0007] Furthermore, the use of the insulation layer combined with multiple sealing cords makes the SEOS architecture complex, making its manufacture and assembly expensive and time-consuming, not to mention the intrinsic fragility due to the insulation layer made of mica.

[0008] An aim of the present invention is to remedy at least one of the aforementioned drawbacks.

[0009] Another aim of the invention is to propose a solution to simplify the SEOS architecture.

[0010] Another aim of the invention is to propose a solution making the manufacturing of SEOS less time-consuming and / or less expensive. Statement of the invention

[0011] The invention proposes to achieve at least one of the aforementioned aims by a spacer for a solid oxide electrochemical device, said device comprising: - at least one interconnector (102,104), - a solid oxide electrochemical cell (106) disposed between said interconnector (102, 104) and another interconnector, and - said spacer, arranged between said interconnectors (102, 104), in particular, around said cell; characterized in that said spacer (202): - comprises a layer, called the main layer, made of a ceramic matrix composite material, called CMC material, or of a precursor of said CMC material, electrically insulating; and - is partly, or entirely, gas-tight.

[0012] Thus, the invention proposes the use of a gas-tight spacer which comprises a main layer made of a CMC material, or a CMC precursor, which is electrically insulating. Thus, the electrical insulation between the interconnectors and the gas-tightness between the interconnectors is directly ensured by the spacer. In other words, in the electrochemical device, these two functions are ensured by a single part, namely the spacer which comprises a main layer made of a CMC material, which simplifies the architecture of the electrochemical device and therefore of the SEOS, making the manufacturing of the SEOS less time-consuming and less expensive.

[0013] In addition, the spacer comprising the main layer made of CMC material has superior mechanical strength compared to a spacer made of a mica layer, allowing for simpler handling and manufacturing. Thus, the assembly of the spacer with the other parts of the electrochemical device is easier, which makes the manufacturing of the electrochemical device, and therefore of the SEOS, simpler, less time-consuming and less expensive.

[0014] By "gastight" or "tight" is meant a barrier to the passage of gas, preventing the passage of gases. In the present invention, it is believed that each sealed portion of the spacer is gastight when it opposes the passage of gases, and in particular the passage of hydrogen, so that the quantity of gas passing through said sealed portion is less than or equal to 6.10' 6 g / minute / cm 2 , especially at 3.10' 6 g / minute / cm 2, and even more particularly at 6.10' 7 g / minute / cm 2 : - at a temperature between 600°C and 850°C; and - when the pressure difference on either side of said sealed part is less than or equal to 100 mbar.

[0015] In an electrochemical device, gas-tightness means a seal that prevents communication between the fluids present in the different zones of said electrochemical device and in particular, a seal between: - the two zones located on either side of the electrochemical cell; and - possibly a flow supply channel entering said electrochemical device; and - possibly a flow extraction channel leaving said electrochemical device. This seal must be sufficient to prevent the mixing of the different gas flows so as not to impair the operation of the electrochemical device, or not to damage the electrochemical device. The spacer according to the invention can ensure at least one of these seals.

[0016] Furthermore, "gastight" or "tight" means a seal against gases present in the electrochemical device, at least at the operating temperature of said device. In other words, the spacer must be tight against gases present in the electrochemical device at least at the operating temperature of said electrochemical device. This seal may be achieved with a material that is gastight at all temperatures. Alternatively, this seal may be achieved with a material that is not initially gastight, for example at room temperature, but which becomes gastight at the operating temperature of the electrochemical device. For example, glass particles may not be gastight at room temperature, but give rise to a gastight sintered glass when said particles are heated to a temperature above the glass transition temperature of the glass.As will be described in the. Subsequently, gas tightness can be achieved in different ways, according to one of the variants described below.

[0017] By "electrically insulating" is meant electrical insulation at least at the operating temperature of the electrochemical device. In other words, the spacer must be electrically insulating at least at the operating temperature of said electrochemical device. This electrical insulation can be achieved with a material that is electrically insulating at all temperatures. Alternatively, this electrical insulation can be achieved with a material that is not initially electrically insulating, for example at room temperature, but which becomes electrically insulating at the operating temperature of the electrochemical device.

[0018] Furthermore, by "electrically insulating" is meant an electrical conductivity below a predefined limit, since any material can be electrically conductive to some extent.

[0019] By "ceramic matrix composite material", or "CMC material", or "CMC", is conventionally meant a ceramic composed of at least one ceramic textile stiffened by a ceramic matrix. By "precursor of a ceramic matrix composite material", or by "precursor of CMC material", or by "precursor of CMC", is meant a material capable of providing said CMC after exposure to temperature in situ in the solid oxide electrochemical device. For example, a material consisting of at least one ceramic textile incorporated in a matrix based on glass particles is a precursor of CMC when said matrix stiffens said textile after exposure to a temperature higher than the glass transition temperature of said glass.

[0020] A "textile" is an assembly of fibers, possibly a thread, especially an assembly of threads.

[0021] A "fiber" is a filament whose length is greater than 5 times its equivalent diameter. The "equivalent diameter" of a fiber is the diameter of a disk with the same surface area as its cross-section at mid-length.

[0022] In a textile, the fibers can be assembled in a disorderly manner, as in felt or paper, or in one or more preferential directions, preferably in the form of threads, themselves preferably in the form of one or more fabrics. A thread of a textile can be: - a “single yarn”, which is an assembly of fibers which, in cross-section, comprises more than 10, and preferably less than 500,000 fibers, and whose length is greater than 5 times the diameter; or - an “assembled yarn”, which is an assembly of single yarns which, in cross-section, preferably comprises more than 2 and preferably less than 500 single yarns.

[0023] A textile can be in particular: - an organized structure of fibers, and / or threads, simple or assembled, in particular a knit or a fabric, or - a random structure of fibers, and / or threads, single or assembled, for example a veil, and / or fibers not incorporated in the form of threads, said random structure being able to be for example a paper or a felt, a random structure not being preferred.

[0024] A "fabric" is made up of a network of parallel warp threads and weft threads crossing said network transversely.

[0025] A "knit" is made up of a network of threads in the form of loops.

[0026] A "sheet" is made up of a set of parallel wires.

[0027] The term "ceramic" means a product that is neither metallic nor organic. For the purposes of the present invention, carbon is considered a ceramic product. Glass and glass-ceramic are also considered ceramic products for the purposes of this application.

[0028] “Sintered glass” means a monolithic compound of said glass, obtained after heat treatment at a temperature above the glass transition temperature of said glass and cooling.

[0029] By "glass-ceramic material" or "glass-ceramic" is meant a microcrystalline compound obtained by controlled crystallization of a glass-ceramic precursor glass. The controlled crystallization of a precursor glass (conventionally in the solid state) is conventionally carried out during a step which follows, immediately or not, the step of obtaining said glass. precursor. Controlled crystallization is usually called “crystallization heat treatment”.

[0030] Glass-ceramic materials are composed of fine crystallizations (microcrystallizations), generally with an average size of less than 1 μm, bathed in a residual glassy phase. The quantity of glassy phase does not limit the invention. In particular, it may be very low.

[0031] Obtaining a glass-ceramic material therefore requires two stages, namely the manufacture of a precursor glass and then the crystallization of this glass.

[0032] Products manufactured by melting-cooling which, during their manufacture, do not pass through a stage in which they are in the glass state are therefore not glass-ceramic materials. Fused corundum, fused alumina, fused spinels, fused magnesia, fused mullite, fused mullite-zirconia and fused aluminium titanate, possibly doped, are not, in particular, glass-ceramic materials.

[0033] The spacer, made of CMC material, or CMC precursor, is gas-tight and electrically insulating.

[0034] The manufacture of a CMC, or a CMC precursor, may be carried out by any conventional method, and in particular include the following steps: - i) arrangement, on or in a textile, of a slip capable of forming a ceramic matrix after consolidation; - ii) before or after step i), shaping of the textile; - iii) optionally drying so as to obtain at the end of step i), ii) or iii), a CMC precursor; - iv) consolidation of said CMC precursor by heat treatment, preferably by sintering, so as to form the matrix and obtain the CMC.

[0035] In step i), the textile may in particular have the form of a sheet, for example a sheet consisting of threads extending substantially parallel to one another (said threads being called “unidirectional threads”), a knit, a fabric (i.e. a woven textile) or a stack of one or more sheets and / or knits and / or fabrics.

[0036] The textile may preferably have the form of a felt or a fabric or a sheet or a stack of felt(s) and / or sheet(s) and / or fabric(s). The stacking of the fabrics and / or sheets may be carried out in such a way that the threads of the different fabrics or sheets extend substantially all in the same direction, or in 2, 3, 4, 5 or 6 different directions, depending in particular on the desired mechanical properties.

[0037] Preferably, at least a portion of the, preferably all of the, fibers of the textile optionally assembled in the form of single and / or assembled threads, may be fibers comprising more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by mass of oxides.

[0038] Preferably, all fibers may have the same composition.

[0039] The arrangement of the slip in the textile can be carried out, for example, by impregnation.

[0040] Stacking can be done by pressing, or under vacuum, preferably after impregnation.

[0041] The manufacture of slip is well known to those skilled in the art. Slip is typically a suspension, for example of an aqueous base or an organic solvent, containing: - ceramic particles and / or ceramic particle precursors, i.e. compounds which transform into ceramic particles during the manufacture of CMC or CMC precursor, in particular during sintering; and - optionally dispersants, plasticizers, lubricants, and / or binders, preferably temporary.

[0042] The composition of the slip, the size distribution of the ceramic particles or ceramic precursors and the mineral filler of the slip are adapted to the type of fibers and the forming technique. For example, the slip can be placed on or in the textile, in particular by direct lamination, infusion, injection, infiltration or deposition, under atmospheric pressure or under higher pressure or under vacuum, at room temperature or at higher temperature.

[0043] Preferably, the ceramic particles may be particles comprising more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by mass of oxides.

[0044] In step ii), the textile obtained, preferably impregnated with the slip, is shaped. The desired shape is preferably the final shape of the CMC or the CMC precursor. In one embodiment, however, the shape can be modified after hardening of the matrix, for example by machining or by deformation.

[0045] In step iii), optional, drying is carried out. The person skilled in the art knows how to adjust the parameters of this step.

[0046] At the end of step i), ii) or iii), a CMC precursor is obtained.

[0047] In step iv), consolidation is carried out by heat treatment, preferably by sintering.

[0048] The person skilled in the art knows how to adjust the parameters of the process chosen for the manufacture of the CMC precursor, and in particular how to determine the particle size of the raw materials, the water content during shaping, and the temperature of the optional drying step. The person skilled in the art also knows how to adjust the heat treatment temperature and the holding time at this temperature during consolidation.

[0049] Preferably, the CMC may further have one or more of the following optional characteristics, or the CMC precursor allows the production of a CMC having one or more of the following optional characteristics: - the CMC may consist of oxides for more than 90% of its mass, preferably for more than 95% of its mass, preferably for more than 98% of its mass, preferably for more than 99% of its mass, preferably for more than 99.5% of its mass; - the CMC may have a total content (SiOz + AI2O3 + ZrO2 + U2O + Na2O + K2O + MgO + CaO + BaO + B2O3 + P2O5 + SrO + La2O3 + Y2O3 + ZnO) greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, as a percentage by mass based on the oxides; - the CMC may have an AI2O3 content greater than 80%, preferably greater than 85%, preferably greater than 90%, preferably greater than 95%, as a percentage by mass based on the oxides; - the CMC may have a SiOz content greater than 80%, preferably greater than 85%, preferably greater than 90%, preferably greater than 95%, as a percentage by mass based on the oxides; - the CMC may contain more than 20% and less than 80% by volume of fibers, the remainder being made up of the matrix; - the CMC fibers may be composed of more than 90%, preferably more than 95%, preferably more than 99% of oxides, in mass percentage; - the CMC fibers may have a total content (SiOz+A Os) greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, as a percentage by mass; - the CMC fibers may have a SiC content greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, preferably greater than 95%, preferably greater than 99%, as a percentage by mass; - the CMC fibers may have an AI2O3 content greater than 80%, preferably greater than 85%, preferably greater than 90%, preferably greater than 95%, preferably greater than 99%, as a percentage by mass; - CMC fibers can be mullite fibers; - all CMC fibers can have substantially the same chemical composition; - CMC fibers can be arranged in the form of a fabric; - the CMC matrix may be composed of more than 90%, preferably more than 95%, preferably more than 99% of oxides, in mass percentage; - the CMC matrix may comprise AI2O3 and / or SiC; - the CMC matrix may have a total content (SiOz + AI2O3 + ZrO2+ U2O + Na2O + K2O + MgO + CaO + BaO + B2O3 + P2O5 + SrO + La2O3 + Y2O3 + ZnO) greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, as a percentage by mass based on the oxides of the matrix.

[0050] According to embodiments, the spacer may comprise, on part or all of the main layer, a gas-tight layer, called a sealing layer, made of a sealing material.

[0051] In this case, the spacer may be made of a CMC material, or a precursor of such a CMC material, which may be either gas-tight, non-gas-tight, or partially gas-tight.

[0052] This allows for more freedom in the choice of sealing material, and / or CMC material, or CMC material precursor, but above all to adapt the gas tightness to different temperatures, and more generally to different operating conditions of the electrochemical device. For example, for an electrochemical device operating at a temperature of 600°C to 850°C, the sealing material can be chosen as gas tight at these temperatures. This sealing material can be different for a device operating at another temperature, for example 150°C. The same reasoning applies to the gases concerned by the sealing and which can differ from one device to another. Thus, by using the same CMC material, or the same CMC material precursor, for the spacer, it is possible to adapt it to different devices.

[0053] This embodiment also has the advantage of achieving sealing of the spacer quickly and without complication.

[0054] Preferably, in these embodiments, the CMC material, or said CMC material precursor, may have one or more of the optional characteristics described above.

[0055] The sealing material may be deposited, in the form of a layer, on at least a portion of at least one of the faces of the main layer. In particular, a layer of sealing material may be deposited on each face of the main layer, depending on the architecture of the electrochemical device.

[0056] The production of said layer of sealing material can be carried out using any technique known to those skilled in the art.

[0057] The layer of sealing material may be deposited on substantially all of at least one of the faces of the main layer. The sealing layer may also be deposited on only a portion of the surface of the main layer, for example in the form of one or more beads, said portion of the surface being determined so as to ensure sealing within the electrochemical device, as defined above, depending on its architecture.

[0058] The layer of sealing material can be produced using any technique known to those skilled in the art.

[0059] Preferably, the layer of sealing material may have a thickness less than or equal to 0.3 mm, in particular less than or equal to 0.2 mm, in particular less than or equal to 0.15 mm, in particular less than or equal to 0.10 mm, and even more particularly less than or equal to 0.05 mm.

[0060] According to embodiments, the sealing material may be, or may comprise: - glass particles, in particular glass-ceramic precursor glass particles; or - a layer of sintered glass, and in particular a layer of glass-ceramic precursor glass; or - a layer of glass ceramic.

[0061] In a first embodiment, called “mode 1”, the sealing material may be, or may comprise, glass particles. Preferably, the mass complement to the glass particles comprises at least one product chosen from: - an organic solvent, - water, and - an organic product, preferably a binder and / or a plasticizer and / or a dispersant. Preferably, the mass quantity of glass particles in the sealing material may be greater than 60%, preferably greater than 70%, and preferably less than 95%, after drying in air at 20°C for 10 hours.

[0062] In mode 1, the layer comprising glass particles is heat treated at a temperature above the glass transition temperature of the glass, preferably when the spacer is placed in the electrochemical device. If the glass transition temperature of the glass is above the operating temperature of the electrochemical device, said device may be momentarily brought to a temperature above the glass transition temperature before the temperature is then decreased to the operating temperature.

[0063] Preferably in this mode 1, the glass may be a glass-ceramic precursor glass, that is to say a glass capable of leading to a glass-ceramic using an appropriate heat treatment.

[0064] Preferably, said glass-ceramic precursor glass may have a total content (SiOz + AI2O3 + U2O + Na2O + K2O + MgO + CaO + BaO + B2O3 + P2O5 + SrO + La2O3 + Y2O3 + ZnO) greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, as a percentage by mass based on the oxides. Preferably, said vitroceramic precursor glass may also have a total content (SiO2 + MgO + CaO + BaO + B2O3 + SrO) greater than 24%, preferably greater than 30%, preferably greater than 35%, preferably greater than 40%, preferably greater than 45%, or even greater than 50%, or even greater than 55%, or even greater than 60%, or even greater than 65%, as a percentage by mass based on the oxides.

[0065] Preferably, when the glass is a glass-ceramic precursor glass, the layer comprising glass particles conventionally undergoes heat treatment at a temperature capable of generating crystallizations, for example when the spacer is placed in the electrochemical device. If said temperature is higher than the operating temperature of the electrochemical device, said device may be momentarily brought to said temperature before the temperature is then decreased to the operating temperature. Depending on the glass-ceramic precursor glass, the person skilled in the art knows how to determine the conditions of the heat treatment, in particular the temperature and the time at which it is held at this temperature to generate crystallizations, as described for example in document WO 2014 / 160948 A1.

[0066] In a second embodiment, called "mode 2", the sealing material may be, or may comprise, a layer of sintered glass. Preferably, the sealing material may be a layer of sintered glass. The person skilled in the art knows how to produce said layer of sintered glass. It may in particular be obtained by depositing glass particles on the surface of the spacer followed by heat treatment at a temperature above the glass transition temperature of the glass.

[0067] In this mode 2, the sintered glass layer is heat treated at a temperature above the glass transition temperature of the glass, preferably when the spacer is placed in the electrochemical device. If the glass transition temperature of the glass is above the operating temperature of the electrochemical device, said device may be momentarily brought to a temperature above the glass transition temperature before the temperature is then decreased to the operating temperature.

[0068] Preferably in this mode 2, the glass may be a glass-ceramic precursor glass, that is to say a glass capable of leading to a glass-ceramic using an appropriate heat treatment.

[0069] Preferably, said glass-ceramic precursor glass may have a total content (SiOz + AI2O3 + U2O + Na2O + K2O + MgO + CaO + BaO + B2O3 + P2O5 + SrO + La2O3 + Y2O3 + ZnO) greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, in percentage by mass based on the oxides. Preferably, said glass-ceramic precursor glass glass ceramic may also have a total content (SiOz + MgO + CaO + BaO + B2O3 + SrO) greater than 24%, preferably greater than 30%, preferably greater than 35%, preferably greater than 40%, preferably greater than 45%, or even greater than 50%, or even greater than 55%, or even greater than 60%, or even greater than 65%, as a percentage by mass based on the oxides.

[0070] Preferably, when the glass may be a glass-ceramic precursor glass, the sintered glass layer may conventionally undergo a heat treatment at a temperature capable of generating crystallizations, for example when the spacer is placed in the electrochemical device. If said temperature is higher than the operating temperature of the electrochemical device, said device may be momentarily brought to said temperature before the temperature is then decreased to the operating temperature. Depending on the glass-ceramic precursor glass, the person skilled in the art knows how to determine the conditions of the heat treatment, in particular the temperature and the time of holding at this temperature to generate crystallizations, as described for example in document WO 2014 / 160948 A1.

[0071] In a third embodiment, called “mode 3”, the layer of sealing material may be, or may comprise, a layer of glass-ceramic.

[0072] Preferably, the glass-ceramic layer may have a total content (SiOz + AI2O3 + U2O + Na2O + K2O + MgO + CaO + BaO + B2O3 + P2O5 + SrO + La2O3 + Y2O3 + ZnO) greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, as a percentage by mass based on the oxides. Preferably, the glass-ceramic layer may also have a total content (SiO2 + MgO + CaO + BaO + B2O3 + SrO) greater than 24%, preferably greater than 30%, preferably greater than 35%, preferably greater than 40%, preferably greater than 45%, or even greater than 50%, or even greater than 55%, or even greater than 60%, or even greater than 65%, as a percentage by mass based on the oxides.

[0073] Preferably in this mode 3, the glass-ceramic layer undergoes a heat treatment at a temperature above the glass transition temperature of its residual glass phase, when the spacer is placed in the electrochemical device. If the glass transition temperature of the residual glass phase is above the operating temperature of the electrochemical device, said device can be momentarily brought to a temperature above said glass transition temperature before the temperature is then decreased to the operating temperature.

[0074] According to an alternative embodiment, called alternative 1, the CMC material may comprise a matrix which is not gas-tight, or be a precursor of such a CMC material. In this case, the spacer comprises a sealing layer deposited over the entire main layer, such as the sealing layer described above.

[0075] This embodiment variant allows greater freedom in the choice of CMC material, or the precursor of such CMC material, to produce the spacer.

[0076] Preferably, in this variant 1, the CMC material, or the precursor of such a CMC material, may have one or more of the optional characteristics described above.

[0077] According to an embodiment variant, called variant 2, the CMC material comprises a deep waterproof matrix, on only part of the main layer, or be a precursor of such a CMC material.

[0078] In this case, the main layer and therefore the spacer have a deep seal on only part of said main layer, and therefore of said spacer. In other words, the spacer will be gas-tight at depth only for certain parts. This embodiment variant has the advantage of having a seal which is more robust and which is not sensitive to damage which may occur on the surface, without however requiring deep sealing of the entire spacer.

[0079] As explained above, the function of gas sealing is to prevent the mixing of gas flows circulating in different areas of the electrochemical device, for example: - in the two zones located on either side of the electrochemical cell, and - possibly in one / each gas flow supply channel entering the electrochemical device; and - possibly in one / each gas flow evacuation channel leaving the electrochemical device.

[0080] The spacer may be gas-tight at depth but only in certain parts of said spacer located between the different zones in which gas flows circulate, so as to ensure gas-tightness between these different zones. These deep-sealed parts of the spacer may be defined by a sealing pattern. The sealing pattern may comprise: - a portion extending between the two zones of the electrochemical device located on either side of the electrochemical cell, in particular in a direction parallel to the plane formed by the spacer; and / or - a portion extending between one / each gas supply channel entering the electrochemical device and the remainder of the spacer, in particular in a direction perpendicular to the plane formed by the spacer; and / or - a portion extending between one / each gas discharge channel exiting the electrochemical device and the remainder of the spacer, in particular in a direction perpendicular to the plane formed by the spacer.

[0081] Generally, the sealing pattern is defined to ensure the sealing of at least one area of ​​the electrochemical device in which a gas flow circulates, with respect to: - at least one other zone of the electrochemical device in which a gas flow circulates; and - possibly the exterior.

[0082] In this variant 2, the CMC material or CMC precursor may have one or more of the optional characteristics described above, for the parts of the spacer which are not gas-tight.

[0083] In one embodiment of this variant 2, called "variant 2.1", for at least one, in particular each, sealed part of the spacer, the matrix of the CMC precursor may be formed from, or may comprise, glass particles. Preferably, the mass complement to the glass particles may comprise at least one product chosen from an organic solvent, water and an organic product, preferably a binder and / or a plasticizer and / or a dispersant. Preferably, in the / each part of the spacer capable of becoming sealed, the matrix of the CMC precursor may comprise a mass quantity of glass particles greater than 60%, preferably greater than 70%, and preferably less than 95%, after drying in air at 20°C for 10 hours.

[0084] In this variant 2.1, the CMC precursor is heat treated at a temperature above the glass transition temperature of the glass, preferably when the spacer is placed in the electrochemical device. If the glass transition temperature of the glass is above the operating temperature of the electrochemical device, said device may be momentarily brought to a temperature above the glass transition temperature before the temperature is then decreased to the operating temperature.

[0085] Preferably, in variant 2.1, the glass may be a glass-ceramic precursor glass, i.e. a glass capable of leading to a glass-ceramic using suitable heat treatment.

[0086] Preferably, said glass-ceramic precursor glass may have a total content (SiOz + AI2O3 + U2O + Na2O + K2O + MgO + CaO + BaO + B2O3 + P2O5 + SrO + La2O3 + Y2O3 + ZnO) greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, in mass percentage based on oxides. Preferably, said glass-ceramic precursor glass also has a total content (SiO2 + MgO + CaO + BaO + B2O3 + SrO) greater than 24%, preferably greater than 30%, of preferably greater than 35%, preferably greater than 40%, preferably greater than 45%, or even greater than 50%, or even greater than 55%, or even greater than 60%, or even greater than 65%, as a percentage by mass based on the oxides.

[0087] Preferably, when the glass is a glass-ceramic precursor glass, the CMC precursor conventionally undergoes a heat treatment at a temperature capable of generating crystallizations in said glass, preferably when the spacer is placed in the electrochemical device. If said temperature is higher than the operating temperature of the electrochemical device, said device may be momentarily brought to said temperature before the temperature is then decreased to the operating temperature. Depending on the glass-ceramic precursor glass, the person skilled in the art knows how to determine the conditions of the heat treatment, in particular the temperature and the time of holding at this temperature to generate crystallizations, as described for example in document WO 2014 / 160948 A1.

[0088] In an embodiment of variant 2, called “variant 2.2”, for at least one, in particular each, sealed part of the spacer, the matrix of the CMC or of the CMC precursor may be, or may comprise, a sintered glass. The person skilled in the art knows how to produce said matrix from a sintered glass. It may in particular be obtained using glass particles heat-treated at a temperature above the glass transition temperature of the glass.

[0089] Preferably, in variant 2.2, the glass may be a glass-ceramic precursor glass, i.e. a glass capable of leading to a glass-ceramic using suitable heat treatment.

[0090] Preferably, said glass-ceramic precursor glass may have a total content (SiOz + AI2O3 + U2O + Na2O + K2O + MgO + CaO + BaO + B2O3 + P2O5 + SrO + La2O3 + Y2O3 + ZnO) greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, in percentage by mass based on the oxides. Preferably, said glass-ceramic precursor glass also has a total content (SiO2 + MgO + CaO + BaO + B2O3 + SrO) greater than 24%, preferably greater than 30%, preferably greater than 35%, preferably greater than 40%, preferably greater than 45%, or even greater than 50%, or even greater than 55%, or even greater than 60%, or even greater than 65%, as a percentage by mass based on the oxides.

[0091] Preferably, when the glass is a glass-ceramic precursor glass, the CMC or CMC precursor conventionally undergoes a heat treatment at a temperature capable of generating crystallizations in said glass, preferably when the spacer is placed in the electrochemical device. If said temperature is higher than the operating temperature of the electrochemical device, said device may be momentarily brought to said temperature before the temperature is then decreased to the operating temperature. Depending on the glass-ceramic precursor glass, the person skilled in the art knows how to determine the conditions of the heat treatment, in particular the temperature and the time of holding at this temperature to generate crystallizations, as described for example in document WO 2014 / 160948 A1.

[0092] In an embodiment of variant 2, called “variant 2.3”, for at least one, in particular each, sealed part of the spacer, the matrix of the CMC or of the CMC precursor may be, or may comprise, a glass-ceramic.

[0093] Preferably, said glass-ceramic may have a total content (SiOz + AI2O3 + IJ2O + Na2O + K2O + MgO + CaO + BaO + B2O3 + P2O5 + SrO + La2O3 + Y2O3 + ZnO) greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, as a percentage by mass based on the oxides. Preferably, said glass-ceramic may have a total content (SiO2 + MgO + CaO + BaO + B2O3 + SrO) greater than 24%, preferably greater than 30%, preferably greater than 35%, preferably greater than 40%, preferably greater than 45%, or even greater than 50%, or even greater than 55%, or even greater than 60%, or even greater than 65%, as a percentage by mass based on the oxides.

[0094] The spacer according to variant 2 can, for example, be manufactured using an impregnation technique involving masking.

[0095] The part of the fibers intended to receive the gas-tight matrix can be masked using a material, for example an organic material, so as to reproduce the sealing pattern. The fibers can then be impregnated with a non-gas-tight matrix. The masking is then removed, for example, using a thermal or chemical treatment. Then the fiber parts that are accessible again, following removal of the masking material, are impregnated with a gas-tight matrix, in particular as described in variants 2.1, 2.2 or 2.3.

[0096] In this variant 2, the spacer may not include a sealing layer. Indeed, in this case, the use of a sealing material is not necessary, the sealing of the parts of the spacer being mainly ensured by the matrix of the CMC material. Preferably, the spacer consists of the main layer made of said CMC material or a precursor of said CMC material.

[0097] Alternatively, the spacer may comprise, preferably consist of, a sealing layer deposited on the main layer: - over the entirety of said main layer; - or only on a part of said main layer, for example at the level of at least one part of said main layer which is not watertight at depth.

[0098] The sealing layer may be that described above, in particular a sealing layer obtained according to one of the methods 1-3 described above.

[0099] In other words, variant 2 of the CMC material can be combined with embodiments 1-3 of the sealing layer.

[0100] According to an embodiment variant, called variant 3, the CMC material may comprise a deep waterproof matrix, over the entire main layer, or be a precursor of such a CMC material.

[0101] In other words, the main layer, and therefore the spacer, can be gas-tight in depth, or in its thickness, for all parts of said main layer, and therefore of the spacer.

[0102] In this variant 3, the spacer can be made of a CMC material whose matrix is ​​gas-tight over its entire depth, or of a precursor of such a CMC material.

[0103] In this variant 3, the use of a sealing material is therefore not necessary, but is not excluded either, the sealing being ensured by the CMC matrix, in all parts of said spacer.

[0104] This variant 3 has the advantage of having a seal that is more robust and is not sensitive to damage that may occur on the surface. In addition, since the gas seal is on all parts of the spacer, the implementation of the spacer in the electrochemical device is simplified.

[0105] In an embodiment of variant 3, called “variant 3.1”, the matrix of the CMC material precursor may be formed from, or may comprise, glass particles. Preferably, the mass complement to the glass particles may comprise at least one product chosen from an organic solvent, water and an organic product, preferably a binder and / or a plasticizer and / or a dispersant. Preferably, the matrix of the CMC precursor may comprise a mass quantity of glass particles greater than 60%, preferably greater than 70%, and preferably less than 95%, after drying in air at 20°C for 10 hours.

[0106] In variant 3.1, the CMC precursor is heat treated at a temperature above the glass transition temperature of the glass, preferably when the spacer is placed in the electrochemical device. If the glass transition temperature of the glass is above the operating temperature of the electrochemical device, said device may be momentarily brought to a temperature above the glass transition temperature before the temperature is then decreased to the operating temperature.

[0107] Preferably, in variant 3.1, the glass may be a glass-ceramic precursor glass, i.e. a glass capable of leading to a glass-ceramic using suitable heat treatment.

[0108] Preferably, said glass-ceramic precursor glass may have a total content (SiOz + AI2O3 + U2O + Na2O + K2O + MgO + CaO + BaO + B2O3 + P2O5 + SrO + La2O3 + Y2O3 + ZnO) greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, as a percentage by mass based on the oxides. Preferably, said glass-ceramic precursor glass may have a total content (SiO2 + MgO + CaO + BaO + B2O3 + SrO) greater than 24%, preferably greater than 30%, preferably greater than 35%, preferably greater than 40%, preferably greater than 45%, or even greater than 50%, or even greater than 55%, or even greater than 60%, or even greater than 65%, as a percentage by mass based on the oxides.

[0109] Preferably, when the glass is a glass-ceramic precursor glass, the CMC precursor conventionally undergoes a heat treatment at a temperature capable of generating crystallizations in said glass, preferably when the spacer is placed in the electrochemical device. If said temperature is higher than the operating temperature of the electrochemical device, said device may be momentarily brought to said temperature before the temperature is then decreased to the operating temperature. Depending on the glass-ceramic precursor glass, the person skilled in the art knows how to determine the conditions of the heat treatment, in particular the temperature and the time of holding at this temperature to generate crystallizations, as described for example in document WO 2014 / 160948 A1.

[0110] In an embodiment of variant 3, called “variant 3.2”, the matrix of the CMC or of the CMC precursor may be, or may comprise, a sintered glass. The person skilled in the art knows how to produce said matrix from a sintered glass. It may in particular be obtained using glass particles heat-treated at a temperature above the glass transition temperature of the glass. [YES] Preferably, in variant 3.2, the glass may be a glass-ceramic precursor glass, i.e. a glass capable of leading to a glass-ceramic using suitable heat treatment.

[0112] Preferably, said glass-ceramic precursor glass may have a total content (SiOz + AI2O3 + U2O + Na2O + K2O + MgO + CaO + BaO + B2O3 + P2O5 + SrO + La2O3 + Y2O3 + ZnO) greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, as a percentage by mass based on the oxides. Preferably, said glass-ceramic precursor glass may have a total content (SiO2 + MgO + CaO + BaO + B2O3 + SrO) greater than 24%, preferably greater than 30%, preferably greater than 35%, preferably greater than 40%, preferably greater than 45%, or even greater than 50%, or even greater than 55%, or even greater than 60%, or even greater than 65%, as a percentage by mass based on the oxides.

[0113] Preferably, when the glass is a glass-ceramic precursor glass, the CMC or CMC precursor conventionally undergoes a heat treatment at a temperature capable of generating crystallizations in said glass, preferably when the spacer is placed in the electrochemical device. If said temperature is higher than the operating temperature of the electrochemical device, said device may be momentarily brought to said temperature before the temperature is then decreased to the operating temperature. Depending on the glass-ceramic precursor glass, the person skilled in the art knows how to determine the conditions of the heat treatment, in particular the temperature and the time of holding at this temperature to generate crystallizations, as described for example in WO 2014 / 160948 A1.

[0114] In one embodiment of variant 3, referred to as “mode 3.3”, the matrix of the CMC or the CMC precursor may be, or may comprise, a glass-ceramic.

[0115] Preferably, said glass-ceramic may have a total content (SiO2 + AI2O3 + IJ2O + Na2O + K2O + MgO + CaO + BaO + B2O3 + P2O5 + SrO + La2O3 + Y2O3 + ZnO) greater than 70%, preferably greater than 75%, preferably greater than 80%, preferably greater than 85%, preferably greater than 90%, in percentage by mass based on the oxides. Preferably, said glass-ceramic may have a total content (SiO2 + MgO + CaO + BaO + B2O3 + SrO) greater than 24%, preferably greater than 30%, preferably greater than 35%, preferably greater than 40%, preferably greater than 45%, or even greater than 50%, or even greater than 55%, or even greater than 60%, or even greater than 65%, as a percentage by mass based on the oxides.

[0116] In variant 3, the spacer may not have a sealing layer. Indeed, in this case, the use of a sealing material is not necessary, the sealing of the spacer being ensured by the matrix of the CMC material over the entire extent of the spacer. Preferably, the spacer consists of the main layer made of said CMC material or a precursor of said CMC material.

[0117] Alternatively, in variant 3, the spacer may comprise, preferably consist of, a sealing layer deposited on the main layer: - over the entirety of said main layer; - or only on a part of said main layer, for example to reinforce the sealing of certain parts of said spacer.

[0118] The sealing layer may be that described above, in particular a sealing layer obtained according to one of the methods 1-3 described above.

[0119] In other words, variant 3 of the CMC material can be combined with embodiments 1-3 of the sealing layer.

[0120] In an alternative embodiment, called “alternative 4”, the CMC material may comprise a matrix comprising a glass-ceramic precursor glass. In embodiments, the glass-ceramic precursor glass may be in the form of: - glass particles, as in variants 2.1 and / or 3.1 described above; or - a sintered glass, as in variants 2.2 and / or 3.2 described above.

[0121] In variant 4, the spacer may not have a sealing layer. Indeed, in this case, the use of a sealing material is not necessary. Preferably, the spacer consists of the main layer made of said CMC material or a precursor of said CMC material.

[0122] In variant 4, the spacer may comprise a sealing layer, as described above with reference to variant 1. In other words, variant 4 of the CMC material may be combined with embodiments 1-3 of the sealing layer.

[0123] The spacer can have any geometric shape depending on the architecture of the electrochemical device, and in particular the stack.

[0124] For example, the spacer may have a generally round shape, or a polygonal shape, for example a square, rectangle, etc.

[0125] The spacer can have any other shape, simpler or more complex.

[0126] The spacer can come in the form of several pieces.

[0127] Preferably, the spacer can be in the form of a single, single-piece part. This simplifies handling of the spacer. In addition, its assembly in each electrochemical device within the stack is simpler and less time-consuming.

[0128] Depending on the embodiments, the spacer may include a central opening allowing: - the passage of gas to, or from, the electrochemical cell; and / or - an electrical contact between: ■ the electrochemical cell, and ■ one, or each, interconnector, or an electrical contact part disposed between said electrochemical cell and said interconnector

[0129] This central opening can be of any shape.

[0130] This central opening can be of any dimension determined according to the size of the electrochemical cell and the architecture of the electrochemical device.

[0131] According to another aspect of the present invention, there is provided a solid oxide electrochemical device comprising: - at least one electrically conductive interconnector, - a solid oxide electrochemical cell arranged between said interconnector and another interconnector, and - a spacer according to the invention, arranged between said two interconnectors.

[0132] Such an electrochemical device has a simpler architecture and is easier to manufacture, while being less time-consuming and less expensive. Electrical insulation and gas-tightness between the interconnectors are ensured by the spacer, which is also easier to handle.

[0133] As mentioned above, the shape and dimensions of the spacer can be determined based on the architecture of the electrochemical device.

[0134] According to embodiments, the spacer may have a thickness greater than the thickness of the electrochemical cell.

[0135] This makes it possible to accommodate the electrochemical cell but also, optionally, one or more electrical contact elements between said electrochemical cell and the, or each, interconnector, without losing contact between the spacer and said at least one interconnector.

[0136] Different positions can be imagined between the spacer and the electrochemical cell, depending on the architecture of the electrochemical device.

[0137] According to embodiments, the electrochemical cell may be arranged on the spacer, above a central opening provided in said spacer. In this case, the central opening is smaller than the cell electrochemical and the cell is placed on the spacer on the side of one of these faces.

[0138] For example, a thinner support lip can be provided on the spacer around the central opening, at the cell size or slightly larger than the cell size, so that the cell can be placed on said support lip. Of course, other embodiments are possible.

[0139] This embodiment has the advantage of facilitating, in addition to the sealing between the interconnectors, the sealing between the cell and the spacer.

[0140] According to an exemplary embodiment, in this case, the cell can be fixed to the spacer, which can allow the cell and the spacer to be assembled before placing them in the electrochemical device.

[0141] According to embodiments, the electrochemical cell can be arranged inside a central opening provided in said spacer, in particular without physical contact with said spacer.

[0142] In this case, the cell is completely surrounded by the spacer.

[0143] According to an exemplary embodiment, in this case, the cell can be attached to an interconnector of the electrochemical device, or to any other part of the electrochemical device, depending on the architecture of said electrochemical device.

[0144] According to another aspect of the same invention, there is provided a solid oxide electrochemical system comprising a stack of several electrochemical devices of which at least one is an electrochemical device according to the invention.

[0145] Preferably, each electrochemical device of the system according to the invention is an electrochemical device according to the invention. The end electrochemical devices comprise an interconnector which is located on the side of the stack: the other interconnector, i.e. the interconnector located on the side opposite the stack, corresponds to a connecting piece of the stack. This connecting piece is also called a "manifold".

[0146] According to embodiments, the electrochemical system according to the invention may be a solid oxide electrolyser for the electrolysis of water vapour at high temperature, for example at a temperature between 600°C and 850°C.

[0147] According to embodiments, the electrochemical system according to the invention may be a solid oxide fuel cell, in particular for the generation of electricity by oxidation of a gas, and in particular of H2.

[0148] Of course, these examples are in no way limiting and the electrochemical system according to the invention can be of any type of electrochemical system. Description of figures and embodiments

[0149] Other advantages and characteristics will appear on examining the detailed description of non-limiting embodiments, and the attached drawings in which: - FIGURE 1 is a schematic representation of a non-limiting exemplary embodiment of a unitary electrochemical device of the state of the art; - FIGURES 2a-2c are schematic representations of three variants of a non-limiting exemplary embodiment of a unitary electrochemical device according to the invention; - FIGURES 3a and 3c are schematic representations of three variants of another non-limiting exemplary embodiment of a unitary electrochemical device according to the invention; - FIGURES 4a-4c are schematic representations of three variants of another non-limiting exemplary embodiment of a unitary electrochemical device according to the invention; and - FIGURE 5 is a schematic representation of a non-limiting exemplary embodiment of an electrochemical system according to the invention.

[0150] It is understood that the embodiments which will be described below are in no way limiting. In particular, it is possible to imagine variants of the invention comprising only a selection of characteristics described below isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art. This selection includes at least one preferably functional characteristic without structural details, or with only part of the structural details if it is this part which is only sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art.

[0151] In particular, all the variants and embodiments described can be combined with each other if there is no technical obstacle to this combination.

[0152] In the figures and in the rest of the description, the elements common to several figures retain the same reference.

[0153] FIGURE 1 is a schematic representation of a non-limiting exemplary embodiment of an electrochemical device according to the state of the art, in a sectional view.

[0154] The electrochemical device 100 of FIGURE 1 may, for example, be an electrochemical device for a solid oxide electrolyzer, SOE, or for a solid oxide fuel cell, SOFC, or for any other electrochemical system of the electrolyzer or fuel cell type.

[0155] The electrochemical device 100 comprises an interconnector 102, intended to cooperate with a second interconnector 104, for example of another electrochemical device, similar or identical.

[0156] The electrochemical device 100 further comprises an electrochemical cell 106 disposed between the interconnectors 102 and 104.

[0157] Each interconnector 102-104 is electrically conductive to supply the electrochemical cell 106 with electric current, for example in the case of an electrolyzer, or to capture an electric current generated at the electrochemical cell 106, for example in the case of a fuel cell.

[0158] The electrochemical cell 106 may be any type of electrochemical cell, in particular an electrochemical cell carrying out a redox reaction of compounds in a gas stream supplied to said electrochemical cell 106. For example, the electrochemical cell may be a cell of a solid oxide electrolyzer for decomposing water vapor molecules and producing a hydrogen-rich gas stream. For example, the electrochemical cell may be a cell of a solid oxide fuel cell for oxidizing hydrogen molecules with oxygen molecules to produce an electric current.

[0159] The electrochemical cell 106 may have any type of architecture. For example, the electrochemical cell may be composed of several layers of materials, one of these layers providing, among other things, a mechanical support function.

[0160] Optionally, the electrochemical device 100 may comprise an electrical contact layer (not shown) between the electrochemical cell 106 and the interconnector 102. Such an electrical contact layer may be made by a grid of an electrically conductive material, such as nickel, allowing the passage of the gas flow while ensuring electrical contact between the interconnector 102 and the electrochemical cell 106.

[0161] Optionally, the electrochemical device 100 may comprise an electrical contact layer (not shown) between the electrochemical cell 106 and the interconnector 104. Such an electrical contact layer may be produced in any possible form, for example in the form of a layer of LSM (for “lanthanum strontium manganite”) comprising gas circulation channels, thus allowing the passage of the gas flow while ensuring electrical contact between the interconnector 104 and the electrochemical cell 106.

[0162] The electrochemical device 100 further comprises a spacer 108 disposed between the interconnectors 102-104. The role of this spacer 108 is to provide electrical insulation between the interconnectors 102-104 so as not to electrically short-circuit the electrochemical cell 106. Generally, this spacer 108 is made of a mica-based material, which is electrically insulating at the operating temperature of the electrochemical device, this temperature being able for example to reach 600°C-850°C, or even higher temperatures, for example in the case of a solid oxide electrolyser, SOE.

[0163] In the example shown, the gas flow(s) is(are) supplied to the electrochemical cell by an inlet channel, CE, and recovered from the electrochemical cell, by an outlet channel, CS, each of the channels CE and CS passing through the interconnectors 102-104 and the spacer 108. One of the interconnectors 102-104 comprises a passage, for example formed by channels provided in the thickness of said interconnector 102-104, allowing the gas flow to pass from the channel CE to the electrochemical cell 106. The other of the interconnectors 104-102 also comprises a passage, for example formed by channels provided in the thickness of said interconnector 104-102, allowing the gas flow coming from the electrochemical cell 106 to be evacuated to the channel CS. According to an exemplary embodiment, the passage provided in one of the interconnectors 102-104 for the gas flow is arranged in a direction perpendicular to that of the passage provided in the other of the interconnectors 104-102.In the example shown, the circulation of the gas flow is indicated by dotted arrows.

[0164] However, the spacer made of a mica-based material, or a similar material, is not gas-tight. Thus, multiple gaskets 110 are provided in the electrochemical device 100 to provide gas-tightness between the interconnectors 102-104 and the electrochemical cell 106, so as to channel the gas flow(s) and direct the gas flow entering the electrochemical device 100 to the electrochemical cell 106, and collect the gas flow coming from the electrochemical cell 106 for evacuation from the electrochemical device 100. The depositing these seals 114 is time-consuming and is a sensitive operation because the slightest seal defect will cause a leak directly impacting the operation of the electrochemical device 100, or even leading to degradation of the electrochemical device 100. These seals 110 are generally made of sintered glass.

[0165] Furthermore, and above all, mica is a fragile material, which is difficult to work and handle. It is a source of fragility for the electrochemical device. This problem is accentuated when the electrochemical device is compressed, or put under pressure, due to the conditions in which the electrochemical reaction takes place.

[0166] All of these elements make the architecture of the electrochemical device 100 of FIGURE 1 complex, not very robust, and time-consuming and expensive to produce.

[0167] The invention proposes to remedy at least one of these drawbacks, partially or totally.

[0168] FIGURES 2a-2c are schematic representations of three variants of a non-limiting exemplary embodiment of an electrochemical device 200 according to the invention, in a sectional view.

[0169] Each of the variations of the device 200 shown in FIGURES 2a, 2b and 2c includes all of the elements of the unitary electrochemical device 100 of FIGURE 1, except for the differences noted below.

[0170] The electrochemical device 200 may, for example, be an electrochemical device for a solid oxide electrolyzer, SOE, or for a solid oxide fuel cell, SOFC, or for any other electrochemical system of the electrolyzer or fuel cell type.

[0171] The electrochemical device 200 comprises at least one of the two interconnectors 102 and 104, the electrochemical cell 106. The circulation of the gas flows in the electrochemical device 200 is identical to that of the unitary electrochemical device 100 of FIGURE 1.

[0172] The electrochemical device 200 comprises, in place of the spacer made of a mica-based material 108, a spacer 202 comprising a layer 204, called the main layer, made of a ceramic matrix composite material, CMC material, electrically insulating. The spacer 202 is furthermore gas-tight, over part or all of said spacer 202.

[0173] The spacer 202, made of CMC material, has superior mechanical strength compared to a mica layer, allowing for simpler handling and manufacturing. Thus, the assembly of the spacer 202 with the other parts of the electrochemical device is easier, making the manufacturing of the electrochemical device 200 simpler, less time-consuming and less expensive.

[0174] In addition, the spacer 202 is gas-tight and electrically insulating. Thus, the electrical insulation between the interconnectors 102-104 and the gas-tightness between said interconnectors 102-104 is directly ensured by the spacer 202. In other words, in the electrochemical device 200, these two functions are ensured by a single part, namely the spacer 202, which simplifies the architecture of the electrochemical device, making the manufacture of said electrochemical device less time-consuming and less expensive.

[0175] In all the variants shown in FIGURES 2a-2c, the spacer 202 is made in a single, monobloc piece.

[0176] The gas tightness of the spacer 202 can be obtained in one of the embodiments described above: - by the CMC material or the precursor of said CMC material used for the main layer 204, and / or - by a sealing layer deposited on the main layer. According to non-limiting exemplary embodiments, the gas-tightness of the spacer 202 can be obtained: - according to variant 1 of the CMC material or of the precursor of said CMC combined with a sealing layer in particular according to one of the modes 1-3 of said sealing layer; - according to variant 2 of the CMC material or the precursor of said CMC, optionally combined with a sealing layer in particular according to one of the modes 1-3 of said sealing layer; - according to variant 3 of the CMC material or of the precursor of said CMC, optionally combined with a sealing layer, in particular according to one of the modes 1-3 of said sealing layer.

[0177] In the variant shown in FIGURE 2a, the spacer 202 is completely sealed in depth. To do this, the spacer 202 comprises a main layer 204 made according to variant 3 described above. For example, the main layer 204 is made according to variant 3.3, that is to say with a CMC material, or a precursor of a CMC material, the matrix of which is formed by, or comprises, a glass-ceramic. In this variant, the spacer 202 consists of the main layer 204 so that said main layer 204 forms said spacer 202.

[0178] In the variant shown in FIGURE 2b, the spacer 202 is not sealed in depth, but only on the surface. To do this, the spacer 202 comprises a main layer 204 produced according to variant 1 described above. The main layer 204 of the spacer 202 is produced with a CMC material, or a precursor of said CMC material, which is not gas-tight, and the spacer 202 further comprises a layer 206 of sealing material deposited on the main layer 204. The sealing layer 206 can be obtained according to one of the modes 1-3 of the sealing layer described above, and in particular according to mode 2 in which the sealing layer 206 is formed by a sintered glass, preferably a glass-ceramic precursor glass.

[0179] In the variant shown in FIGURE 2c, the spacer 202 comprises a main layer 204 which is gas-tight in depth, but only in certain parts of the spacer, according to a sealing pattern 208. To do this, the main layer 204 of the spacer 202 is made according to the variant 2 described above. The main layer 204 of the spacer 202 is made with a CMC material, or a precursor of said CMC material, which is gas-tight, only for certain determined parts according to the sealing pattern 208.

[0180] In the examples of FIGURES 2a-2c, all of the seals 114 are retained. Thus, the electrochemical device 200 comprises: - sealing gaskets 110 between the spacer 202 and each of the interconnectors 102 and 104, on either side of the supply channel CE of the incoming gas flow, - sealing gaskets 110 between the spacer 202 and each of the interconnectors 102 and 104, on either side of the evacuation channel CS of the outgoing gas flow, - sealing gaskets 110 between the cell 106 and each of the interconnectors 102 and 104, at the periphery of the cell 106.

[0181] FIGURES 3a-3c are schematic representations of three variants of a second non-limiting exemplary embodiment of an electrochemical device according to the invention, in a sectional view.

[0182] Each of the electrochemical device 300 variants of FIGURES 3a-3c includes all of the elements of the electrochemical device 200, except for the differences noted below.

[0183] The electrochemical device 300 does not include sealing gaskets 110 between the spacer 202 and each of the interconnectors 102 and 104. Indeed, depending on the applications, the spacer 202 being already sealed, either on the surface or in depth, it is entirely possible not to use sealing gaskets between the spacer 202 and the interconnectors 102-104.

[0184] Like the device 200, the spacer 202 of the device 300 can be made gas-tight according to one of the variants described above.

[0185] In the variant shown in FIGURE 3a, the spacer 202 comprises a main layer 204 which is completely watertight in depth. To do this, the main layer 204 of the spacer 202 is produced according to variant 3 described above. For example, the main layer 204 of the spacer 202 is produced according to variant 3.2, i.e. with a CMC material, or a precursor of a CMC material, the matrix of which is formed by, or comprises, a sintered glass, said glass preferably being a glass-ceramic precursor glass. In this variant, the spacer 202 consists of the main layer 204 so that said main layer 204 forms said spacer 202.

[0186] In the variant shown in FIGURE 3b, the spacer 202 is not sealed in depth, but only on the surface. To do this, the main layer 204 of the spacer 202 is produced according to variant 1 described above. The main layer 204 of the spacer 202 is produced with a CMC material, or a precursor of said CMC material, which is not gas-tight, and the spacer 202 further comprises a layer 206 of sealing material deposited on the main layer 204. The sealing layer 206 can be obtained according to one of the modes 1-3 of the sealing layer described above, and in particular according to mode 2 in which the sealing layer 204 is formed by a sintered glass, preferably a glass-ceramic precursor glass.

[0187] In the variant shown in FIGURE 3c, the main layer 204 of the spacer 202 is gastight in depth, but only in certain parts of the spacer, according to a sealing pattern 208. To do this, the main layer 204 of the spacer 202 is made according to variant 2 described above. The main layer 204 of the spacer 202 is made with a CMC material, or a precursor of said CMC material, which is gastight only in certain determined parts according to the sealing pattern 208.

[0188] It should be noted that, in the electrochemical device 300, the seals 110 arranged between the cell 106 and each of the interconnectors 102 and 104, at the periphery of the cell 106, are retained.

[0189] According to an alternative not shown, the electrochemical device 300 may comprise only a portion of the seals 110 located between the spacer 202 and at least one of the interconnectors 102 and 104, and shown in the electrochemical device 200. Indeed, depending on the applications, the spacer 202 being already sealed, it is entirely possible not to use as many seals as those shown. in FIGURE 2, and thus reduce the complexity of the architecture of the electrochemical device while retaining part of the seals 110.

[0190] FIGURES 4a-4c are schematic representations of three variants of another non-limiting exemplary embodiment of an electrochemical device according to the invention, in a sectional view.

[0191] Each of the variations of the electrochemical device 400 of FIGURES 4a-4c includes all of the elements of the electrochemical device 200, except for the differences noted below.

[0192] In the electrochemical device 400, the electrochemical cell 106 is arranged on the spacer 202, above the central opening provided in said spacer 202. To do this, the spacer 202 comprises, around the central opening, a part 402, or a lip 402, of smaller thickness compared to the rest of the spacer 202. This lip 402 forms a support for the electrochemical cell 106. Thus, in the electrochemical device 400 the spacer 202 forms a support for the electrochemical cell 106.

[0193] Of course, the thickness of the cell 106 and / or the thickness of the spacer 202, in particular the thickness of the lip 402, can be adjusted to ensure electrical contacts between the electrochemical cell 106 and the interconnectors.

[0194] Like the devices 200 and 300, the spacer 202 of the device 400 can be made gas-tight according to one of the variants described above.

[0195] In the variant shown in FIGURE 4a, the spacer 202 comprises a main layer 204 which is completely sealed in depth. To do this, the main layer 204 of the spacer 202 is produced according to variant 3 described above. For example, the main layer 204 of the spacer 202 is produced according to method 3.3, i.e. with a CMC material, or a precursor of a CMC material, the matrix of which is formed by, or comprises, a glass-ceramic.

[0196] In the variant shown in FIGURE 4b, the spacer 202 is not sealed in depth, but only on the surface. To do this, the main layer 204 of the spacer is made according to variant 1 described above. The main layer 204 of the spacer 202 is made with a CMC material, or a precursor of said CMC material, which is not gas-tight, and the spacer 202 further comprises a layer 206 of sealing material deposited on said main layer 204. The sealing layer 204 can be obtained according to one of the modes 1-3 described above, and in particular according to mode 2 in which the sealing layer 206 is formed by a sintered glass, preferably a glass-ceramic precursor glass.

[0197] In the variant shown in FIGURE 4c, the main layer 204 of the spacer 202 is gastight in depth, but only in certain parts of the spacer 202, according to a sealing pattern 208. To do this, the main layer 204 of the spacer 202 is produced according to variant 2 described above: the main layer 204 of the spacer 202 is produced with a CMC material, or a precursor of said CMC material, which is gastight only in certain determined parts according to the sealing pattern 208.

[0198] In the example shown in FIGURES 4a-4c, the electrochemical device 400 comprises: - sealing gaskets 110 between the spacer 202 and each of the interconnectors 102 and 104, on either side of the supply channel CE of the incoming gas flow, - sealing gaskets 110 between the spacer 202 and each of the interconnectors 102 and 104, on either side of the evacuation channel CS of the outgoing gas flow, - at least one seal 110 between the cell 106 and the spacer 202, at the periphery of the cell 106.

[0199] According to an alternative not shown, the positioning of the electrochemical cell 106 as described with reference to FIGURES 4a-4c can be used in the electrochemical device 300 of FIGURES 3a-3c.

[0200] It is recalled that the FIGURES represent the electrochemical device in a schematic form and not all the elements of said electrochemical device are represented for the sake of clarity and for do not overload the FIGURES. For example, the electrochemical device may include an electrical contact layer (not shown) between the electrochemical cell 106 and the interconnector 102 and / or an electrical contact layer between the electrochemical cell 106 and the interconnector 104.

[0201] FIGURE 5 is a schematic representation of a non-limiting exemplary embodiment of an electrochemical system according to the invention.

[0202] The system 500 may for example be an electrolyzer, and in particular a solid oxide electrolyzer, SOE.

[0203] The SOE solid oxide electrolyser can be used for high temperature electrolysis, for example between 600°C and 800°C, of ​​water vapour to generate a hydrogen stream.

[0204] The electrolyzer 500 comprises a stack 502, also called a stack, of unitary electrochemical devices 504i-504 n. Each unitary electrochemical device 504i may be any one of the electrochemical devices 200, 300, or 400 described above.

[0205] The 504i and 504 unit electrochemical devices n which are located at the ends of the stack 502 do not include an interconnector on the end side of the stack 502 but connectors 506 and 508, also called manifold, for supplying gas flow and electricity to the stack 502.

[0206] The stack 502 is powered by an electric current 510 to carry out the electrochemical reaction.

[0207] The stack 502 is supplied by a first inlet gas stream 512 at high temperature and rich in water vapor. The electrochemical reaction produces a first outlet gas stream 514 rich in hydrogen and a second outlet gas stream 516 rich in oxygen, by decomposition of the water vapor molecules in contact with the electrochemical cell 106 of each electrochemical device 504i. Optionally, the stack 502 can be supplied by a second gas stream 518 at high temperature, for example air, for example to balance the pressures within the stack 502.

[0208] Of course, the electrochemical system 500 may include other components, such as heat exchangers, a hydrogen purification unit, safety valves, etc., which are not shown in FIGURE 5.

[0209] According to another example not shown, the electrochemical system according to the invention may be a fuel cell, and in particular a solid oxide fuel cell, SOFC, to produce an electric current by oxidation of hydrogen molecules for example.

[0210] Of course, the invention is not limited to the examples which have just been described.

Claims

CLAIMS 1. Spacer (202) for a solid oxide electrochemical device (200;300;400), said device (200;300;400) comprising: - at least one interconnector (102,104), - a solid oxide electrochemical cell (106) arranged between said interconnector (102, 104) and another interconnector (102; 104), and - said spacer (202), arranged between said interconnectors (102, 104), in particular, around said cell (106); characterized in that said spacer (202): - comprises a layer, called the main layer, made of a ceramic matrix composite material, called the CMC material, or of a precursor of said CMC material, electrically insulating; and - is partly, or entirely, gas-tight.

2. Spacer (202) according to the preceding claim, characterized in that the spacer comprises, on part or all of the main layer, a gas-tight layer, called a sealing layer, made of a sealing material.

3. Spacer (202) according to the preceding claim, characterized in that the sealing material is, or comprises: - glass particles, in particular glass-ceramic precursor glass particles; or - a layer of sintered glass, and in particular a layer of glass-ceramic precursor glass; or - a layer of glass ceramic.

4. Spacer (202) according to any one of claims 2 or 3, characterized in that the CMC material comprises a matrix which is not gas-tight, said sealing layer being deposited over the entire main layer.

5. Spacer (202) according to any one of claims 1 to 3, characterized in that the CMC material comprises a deep waterproof matrix, on only part of the main layer.

6. Spacer (202) according to any one of claims 1 to 3, characterized in that the CMC material comprises a deep waterproof matrix, over the entire main layer.

7. Spacer (202) according to any one of claims 5 or 6, characterized in that, for at least one sealed part of the main layer: - the CMC precursor matrix comprises glass particles, in particular glass-ceramic precursor glass particles; or - the CMC matrix, or the CMC precursor matrix, is, or comprises, a sintered glass, in particular a glass-ceramic precursor glass; or - the CMC matrix, or the CMC precursor matrix, is, or comprises, a glass-ceramic.

8. Spacer (202) according to any one of the preceding claims, characterized in that said spacer (202) is in the form of a single, single-piece part.

9. Spacer (202) according to any one of the preceding claims, characterized in that said spacer (202) comprises a central opening allowing: - the passage of gas to, or from, the electrochemical cell (106); and / or - an electrical contact between: ■ the electrochemical cell (106), and ■ one, or each, interconnector (102,104), or an electrical contact piece disposed between said electrochemical cell (106) and said interconnector (102,104).

10. Solid oxide electrochemical device (200;300;400) comprising: - at least one electrically conductive interconnector (102,104), - a solid oxide electrochemical cell (106) disposed between said interconnector (102,104) and another interconnector (102,104), and - a spacer (202), according to any one of the preceding claims, arranged between said two interconnectors (102, 104).

11. Device (200; 300; 400) according to the preceding claim, characterized in that the spacer (202) has a thickness greater than the thickness of the electrochemical cell (106).

12. Device (400) according to any one of claims 10 or 11, characterized in that the electrochemical cell (106) is arranged on the spacer (202), above a central opening provided in said spacer (202).

13. Device (200; 300) according to any one of claims 10 or 11, characterized in that the electrochemical cell (106) is arranged inside a central opening provided in the spacer (202), in particular without physical contact with said spacer (202).

14. Solid oxide electrochemical system (500) comprising a stack (502) of several electrochemical devices (502i-502 n ) at least one of which is an electrochemical device (200;300;400) according to any one of claims 10 to 13.

15. System (500) according to the preceding claim, characterized in that said system is a solid oxide electrolyzer for the electrolysis of water vapor at high temperature.

16. System according to claim 14, characterized in that said system is a solid oxide fuel cell.

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