ARRANGEMENT WITH A STACK OF SOEC / SOFC SOLID OXIDE CELLS AND EXTERNAL GUIDES

Description

DOMAINE TECHNIQUE

[0001] The present invention relates to the general field of high temperature electrolysis (HTE), in particular high temperature steam electrolysis (HTSE), respectively designated by the English terms "High Temperature Electrolysis" (HTE) and "High Temperature Steam Electrolysis" (HTSE), of carbon dioxide (CO2) electrolysis, or even of high temperature co-electrolysis of water vapor and carbon dioxide (CO2).

[0002] More specifically, the invention relates to the field of high-temperature solid oxide electrolyzers, usually designated by the acronym SOEC (for "Solid Oxide Electrolysis Cell" in English).

[0003] It also concerns the field of high-temperature solid oxide fuel cells, usually referred to by the acronym SOFC (for "Solid Oxide Fuel Cells" in English).

[0004] Thus, more generally, the invention relates to the field of SOEC / SOFC type solid oxide stacks operating at high temperature.

[0005] More specifically, the invention relates to an assembly comprising a stack of SOEC / SOFC type solid oxide cells and external guiding elements, as well as an associated conditioning method. ÉTAT DE LA TECHNIQUE ANTÉRIEURE

[0006] In a high-temperature solid oxide electrolyzer (SOEC), the process involves converting water vapor (H₂O) into hydrogen (H₂) and oxygen (O₂) using an electric current within the same electrochemical device, and / or converting carbon dioxide (CO₂) into carbon monoxide (CO) and oxygen (O₂). In a high-temperature solid oxide fuel cell (SOFC), the operation is reversed, producing both electricity and heat when fueled by hydrogen (H₂) or other fuels such as methane (CH₄), natural gas, biogas, and oxygen (O₂), typically from air. For simplicity, the following description focuses on the operation of a high-temperature SOEC performing water vapor electrolysis.However, this principle is applicable to the electrolysis of carbon dioxide (CO2), and even to the co-electrolysis of high-temperature steam with carbon dioxide (CO2). Furthermore, this principle can be transposed to the case of a high-temperature solid oxide fuel cell (SOFC).

[0007] To carry out the electrolysis of water, it is advantageous to do so at high temperature, typically between 600 and 1000°C, because it is more advantageous to electrolyze water vapor than liquid water and because part of the energy required for the reaction can be supplied by heat, which is cheaper than electricity.

[0008] To implement high-temperature steam electrolysis (HTSE), a high-temperature solid oxide electrolyzer (SOEC) consists of a stack of elementary units, each comprising a solid oxide electrolysis cell, or electrochemical cell, made up of three stacked anode / electrolyte / cathode layers, and interconnecting plates made of metallic alloys, also called bipolar plates or interconnectors. Each electrochemical cell is sandwiched between two interconnecting plates. A high-temperature solid oxide electrolyzer (SOEC) is therefore an alternating stack of electrochemical cells and interconnectors. A high-temperature solid oxide fuel cell (SOFC) is made up of the same type of stack of elementary units.Because this high-temperature technology is reversible, the same stack can operate in electrolysis mode and produce hydrogen and oxygen from water and electricity, or in fuel cell mode and produce electricity from hydrogen and oxygen.

[0009] Each electrochemical cell consists of an electrolyte / electrode assembly, typically a multilayer ceramic assembly where the electrolyte is formed by a central ion-conducting layer. This layer is solid, dense, and impermeable, sandwiched between two porous layers that form the electrodes. It should be noted that additional layers may exist, but these serve only to improve one or more of the layers already described.

[0010] Electrical and fluidic interconnecting devices are electronic conductors that ensure, from an electrical standpoint, the connection of each electrochemical cell of elementary pattern within the stack of elementary patterns, guaranteeing electrical contact between one face and the cathode of one cell and between the other face and the anode of the next cell. From a fluidic standpoint, they ensure the supply of reactants and the removal of products for each cell. The interconnectors thus perform the functions of supplying and collecting electrical current and delineate gas circulation compartments for distribution and / or collection.

[0011] More specifically, the interconnectors have the main function of ensuring the passage of electric current but also the circulation of gases in the vicinity of each cell (namely: injected water vapor, extracted hydrogen and oxygen for EHT electrolysis; air and fuel including injected hydrogen and extracted water for a SOFC), and of separating the anodic and cathodic compartments of two adjacent cells, which are the gas circulation compartments on the anode and cathode sides of the cells respectively.

[0012] In particular, for a high-temperature solid oxide electrolyzer (SOEC), the cathode compartment contains water vapor and hydrogen, products of the electrochemical reaction, while the anode compartment contains a draining gas, if present, and oxygen, another product of the electrochemical reaction. For a high-temperature solid oxide fuel cell (SOFC), the anode compartment contains the fuel, while the cathode compartment contains the propellant.

[0013] To perform high-temperature steam electrolysis (HTE), steam (H₂O) is injected into the cathode compartment. Under the influence of the electric current applied to the cell, the dissociation of water molecules into steam occurs at the interface between the hydrogen electrode (cathode) and the electrolyte. This dissociation produces hydrogen gas (H₂) and oxygen ions (O₂⁻). The hydrogen (H₂) is collected and discharged from the hydrogen compartment. The oxygen ions (O₂⁻) migrate through the electrolyte and recombine into oxygen (O₂) at the interface between the electrolyte and the oxygen electrode (anode). A draining gas, such as air, can circulate at the anode and thus collect the oxygen generated in gaseous form at the anode.

[0014] To operate a solid oxide fuel cell (SOFC), air (oxygen) is injected into the cathode compartment and hydrogen into the anodic compartment. The oxygen in the air dissociates into O2- ions. These ions migrate through the electrolyte from the cathode to the anode to oxidize the hydrogen and form water, simultaneously producing electricity. In an SOFC, as in SOEC electrolysis, water vapor is found in the hydrogen (H2) compartment. Only the polarity is reversed.

[0015] For example, the figure 1 represents a schematic view showing the operating principle of a high-temperature solid oxide electrolyzer of the SOEC type. The function of such an electrolyzer is to transform water vapor into hydrogen and oxygen according to the following electrochemical reaction: 2 H 2 O → 2 H 2 + O 2 .

[0016] This reaction is carried out electrochemically in the cells of the electrolyzer. As shown schematically on the figure 1 Each elementary electrolysis cell 1 consists of a cathode 2 and an anode 4, placed on either side of a solid electrolyte 3. The two electrodes (cathode and anode) 2 and 4 are electronic and / or ionic conductors, made of porous material, and the electrolyte 3 is gas-tight, an electronic insulator, and an ionic conductor. The electrolyte 3 can, in particular, be an anionic conductor, more precisely an anionic conductor of O2- ions, and the electrolyzer is then called an anionic electrolyzer, as opposed to proton electrolytes (H+).

[0017] Electrochemical reactions take place at the interface between each of the electronic conductors and the ionic conductor.

[0018] At cathode 2, the half-reaction is as follows: 2 H 2 O + 4 e -< → 2 H 2 + 2 O 2-< .

[0019] At anode 4, the half-reaction is as follows: 2 O 2-< → O 2 + 4 e -< .

[0020] Electrolyte 3, intercalated between the two electrodes 2 and 4, is the site of migration of O 2- ions under the effect of the electric field created by the potential difference imposed between the anode 4 and the cathode 2.

[0021] As illustrated in parentheses on the figure 1 The water vapor entering the cathode may be accompanied by hydrogen (H₂), and the hydrogen produced and recovered at the outlet may be accompanied by water vapor. Similarly, as illustrated by the dotted line, a draining gas, such as air, can also be injected at the anode inlet to remove the oxygen produced. The injection of a draining gas also serves as a thermal regulator.

[0022] An elementary electrolyzer, or electrolysis reactor, consists of an elementary cell as described above, with a cathode 2, an electrolyte 3, and an anode 4, and two interconnectors which provide the electrical and fluidic distribution functions.

[0023] To increase the flow rates of hydrogen and oxygen produced, it is known to stack several elementary electrolysis cells on top of each other, separated by interconnectors. The assembly is positioned between two end interconnection plates that support the electrical and gas supplies of the electrolyzer (electrolysis reactor).

[0024] A high-temperature solid oxide electrolyzer of the SOEC type thus comprises at least one, usually a plurality of electrolysis cells stacked one on top of the other, each elementary cell being formed of an electrolyte, a cathode and an anode, the electrolyte being intercalated between the anode and the cathode.

[0025] As previously stated, fluid and electrical interconnection devices that are in electrical contact with one or more electrodes generally provide the functions of supplying and collecting electrical current and delimit one or more gas circulation compartments.

[0026] Thus, the so-called cathodic compartment has the function of distributing the electric current and water vapor as well as recovering hydrogen at the cathode in contact.

[0027] The so-called anodic compartment has the function of distributing the electric current as well as recovering the oxygen produced at the anode in contact, possibly with the help of a draining gas.

[0028] There figure 2 represents an exploded view of elementary motifs of a high-temperature solid oxide electrolyzer of the SOEC type according to the prior art. This electrolyzer comprises a plurality of elementary electrolysis cells C1, C2, of the solid oxide cell (SOEC) type, stacked alternately with interconnectors 5. Each cell C1, C2 consists of a cathode 2.1, 2.2 and an anode (only the anode 4.2 of cell C2 is shown), between which is disposed an electrolyte (only the electrolyte 3.2 of cell C2 is shown).

[0029] The interconnector 5 is a metal alloy component that separates the cathode compartment 50 from the anodic compartment 51, defined by the volumes between the interconnector 5 and the adjacent cathode 2.1 and between the interconnector 5 and the adjacent anode 4.2, respectively. It also distributes the gases to the cells. Water vapor is injected into each element in the cathode compartment 50. The hydrogen produced and residual water vapor at cathodes 2.1 and 2.2 are collected in the cathode compartment 50 downstream of cell C1 and C2 after the water vapor has been dissociated by the cell. The oxygen produced at anode 4.2 is collected in the anodic compartment 51 downstream of cell C1 and C2 after the water vapor has been dissociated by the cell.The interconnector 5 ensures the passage of current between cells C1 and C2 by direct contact with the adjacent electrodes, i.e. between the anode 4.2 and the cathode 2.1.

[0030] To ensure good electrical contact between all the interconnectors, the electrochemical cells and the interconnectors are sandwiched between two rigid plates, called the upper terminal plate and the lower terminal plate, which are electrically insulated from the interconnectors. This resulting sandwich is called a "stack," and thus comprises the upper and lower terminal plates, the electrochemical cells, and the interconnectors. This stack must be kept under compressive force to ensure good electrical continuity of the contact planes between the plates.

[0031] During the first phase of manufacturing the stacks, the glass-ceramic seal is formed by subjecting the stack to a thermal cycle while applying a controlled compressive force to the stack. This thermal cycle is called the conditioning cycle.

[0032] Indeed, the various seals between circuits are ensured by fused glass gaskets. This fused glass is obtained by depositing slip, a precursor to glass. The slip is deposited in the form of beads sandwiched between the interconnecting plates (or interconnectors). This slip then dries in place, resulting in a bead made of glass powder binders. Thus, in a cold state, before the heating cycle that will form the glass, the interconnecting plates are separated by beads of dried slip. These beads will melt during the heating cycle, and the contacts will be established at the reactive zones described previously. The melting of the beads can result in a reduction of more than 50% in the thickness of the slip bead. These beads can also be made of already densified glass, sandwiched between two successive interconnectors in the stack.Just as in the conditioning cycle with dried slip cords, the melting of the glass joint will cause the space between the interconnectors to sag, but to a lesser extent than with slip.

[0033] In all cases, it is important to ensure guidance in a direction perpendicular to the plane of the interconnectors, or collinear with the direction of the compressive force exerted by the interconnecting and end plates. Such guidance guarantees that, during the stack's settling, which occurs during glass formation, the stack's constituent parts (particularly interconnectors, insulating plates, and end plates) remain correctly aligned with each other. During this phase, the stack's height decreases by approximately 50%, resulting in significant vertical movement of the stack.

[0034] The development of industrial systems incorporating high-temperature electrolyzers requires an increase in the volume of gas treated (in SOEC or SOFC). To achieve this, an increase in surface area, the number of cells, and the number of interconnectors is necessary. However, a significant increase in the number of plates, and therefore in the stack height, poses numerous technical challenges, particularly during the manufacturing phases. Indeed, the greater the stack height, the more critical the control of the guidance becomes.

[0035] In current designs, this guidance is provided by cylindrical columns positioned inside the stack structure, passing through the various plates in which cylindrical or oblong holes are machined, sized to the diameter of the columns. The base of these columns is mechanically locked into the lower end plate.

[0036] This type of system has several limitations due to the small diameters of the guide columns imposed by the internal structure of the interconnectors. Achieving satisfactory guidance of numerous thin plates over considerable heights using these columns requires precise control of the relative clearances between the columns and the diameters of the through holes. This type of assembly, with its tight clearances, exposes the system to the risk of rotational jamming, which can occur during the glass-ceramic sealing cycle, during which the stack exhibits a significant drop in height. It should be noted that the force applied to ensure contact between the different plates is not particularly high, and therefore any accidental jamming of the plates relative to their guide elements is problematic.Furthermore, this type of guidance also requires cutting operations on the columns that protrude from the stack after conditioning, which after the thermal cycle cannot be dismantled and remain at the heart of the stack.

[0037] For example, the figures 3A et 3B represent the current guidance solution. Two columns 11 and 12 are used to guide the plates P of the stack 20 (shown here very schematically) as they descend. The plates P can be interconnecting plates, insulating plates, or even the lower and upper end plates. Here, on the figure 3B For example, the upper and lower terminal plates P are considered to be represented; the other plates P sandwiched between them are therefore not shown. On one side, a circular orifice O1 is used, and the fit between the plate P and the column 11 is very fine, for example, on the order of 0.1 mm of clearance J1. On the other side, the orifice O2 in the plate P is oblong in cross-section, leaving a larger clearance J2. Therefore, applying pressure in the center to lower the plates P, as indicated by the arrows F, as the glass-ceramic seals melt, can cause a slight deflection of these plates P, and thus result in a buttressing blockage, represented by AC on the diagram. figure 3B , on column 11 on which the fit is tight. In practice, in order to avoid these risks of AC buttressing, the clearance J1 around the guide column 11 can be drastically increased, which then fundamentally degrades the guiding function and is therefore not at all desirable.

[0038] The document DATABASE WPI, Thompson Scientific, LondonGB; AN 2021-E9634D XP002807937 and the document CN113782802A both describe systems representative of the prior art and which have the identified disadvantages.

[0039] There is therefore a need to offer an effective guidance solution to avoid this buttressing problem while maintaining guidance accuracy during the slump of the plate stack. EXPOSÉ DE L'INVENTION

[0040] The invention aims to remedy at least partially the needs mentioned above and the drawbacks related to prior art achievements.

[0041] The invention thus relates, according to one of its aspects, to an assembly comprising: a stack of high-temperature SOEC / SOFC type solid oxide cells, consisting of a plurality of plates stacked one on top of the other in a vertical direction substantially perpendicular to each horizontal plane, with each plate having an upper surface, a lower surface and an external lateral surface, said plurality of plates comprising at least: a plurality of electrochemical cells each formed of a cathode, an anode and an electrolyte intercalated between the cathode and the anode, and a plurality of interconnectors arranged each between two adjacent electrochemical cells, an upper terminal plate and a lower terminal plate, between which the plurality of electrochemical cells and the plurality of interconnectors are enclosed, at least two guide elements ensuring the vertical stacking guidance of at least a portion of the stack plates, characterized in that said at least two guide elements extend vertically in the vertical direction, bearing against the external lateral surface of each plate of said at least a portion of the plates. According to the invention, at least two guide elements can be fixed by means of a fastening device to a lower support plate on which the stack is placed and / or to an upper support plate under which the stack is placed, and the fastening device can comprise a fastening base, fixed to the lower support plate and / or to the upper support plate, an elastic compression return member, one end of which is in contact with a guide element and the other end is in contact with the fastening base, and a fastening screw mounted on the base.

[0042] The assembly according to the invention may further comprise one or more of the following characteristics taken individually or in any possible technical combinations.

[0043] Each horizontal plane is defined in particular by horizontal directions that are perpendicular to each other. The aforementioned.

[0044] The elastic compression return element can be made of metallic alloy, in particular metallic superalloy, especially nickel-based, for example Inconel ®< 718 or 750, or Haynes ®< 230 ®< , or of ceramic, for example by additive manufacturing, among others.

[0045] In addition, each guide element may include a support device cooperating with the fixing device, including in particular at least one support plane for the elastic compression return element and a support base in contact with the lower support plate and / or the upper support plate.

[0046] In addition, said at least two guiding elements may be at least partly of substantially cylindrical shape and may have, in cross-section with respect to the vertical direction, a substantially circular, triangular, triangular and semi-circular, square and / or rectangular shape.

[0047] Furthermore, these at least two guide elements, particularly those rectangular in cross-section, may be evenly distributed around each plate, with the same number of guide elements on each face of each plate. These at least two guide elements may be present in a number of at least four, six, eight, or more, and in particular in an even number. In the case of four guide elements, these may be positioned centrally with respect to each face of the plate. In the case of eight guide elements, two guide elements may be positioned on either side of each corner of a four-sided plate.

[0048] Furthermore, each plate of said at least a part of the plates may have at least two notches formed on the lateral surface of the plate in which said at least two guide elements, in particular of circular, oval or "V" shape, come to rest.

[0049] Each notch of at least some of the notches may have a "V" shape obtained by the formation of two tangent planes on the lateral surface of the plate.

[0050] The "V" shape can define an angle between 15° and 60°. In addition, the depth of the "V" shape, defined as the height of the "V", between the lateral surface and the union of the two tangent planes, can be between 2 mm and 15 mm, notably on the order of 10 mm.

[0051] Furthermore, the number of said at least two guiding elements may be between 2 and 12, in particular equal to 4.

[0052] Furthermore, at least two guide elements can be held together by means of at least one elastic element extending substantially transversely with respect to the vertical direction.

[0053] Each elastic element may include a sliding element having one end fixed to a guide element, capable of sliding inside a fixed element, having one end fixed to another guide element, the sliding and fixed elements being connected to each other by means of at least one elastic tension return element.

[0054] Furthermore, said at least two guiding elements may be made of at least one electrically insulating material.

[0055] Furthermore, the invention also relates, according to another of its aspects, to a method of conditioning a stack of SOEC / SOFC type solid oxide cells operating at high temperature of an assembly as defined above, characterized in that it comprises the step of guiding in vertical stacking at least a part of the plates constituting the stack by means of said at least two guiding elements. BRÈVE DESCRIPTION DES DESSINS

[0056] The invention will be better understood upon reading the detailed description that follows, the non-limiting examples of its implementation, and upon examination of the schematic and partial figures in the attached drawing, on which: [ Fig. 1 ] is a schematic view showing the operating principle of a high-temperature solid oxide electrolyzer (SOEC), [ Fig. 2 ] is an exploded schematic view of part of a high-temperature solid oxide electrolyzer (SOEC) including interconnectors according to the prior art, [ Fig. 3A] et [Fig. 3B ] represent, schematically and partially, respectively from a top view and from a side view, a principle according to the prior art of guiding the plates of a high-temperature SOEC / SOFC type stack, [ Fig. 4A ] represents, in perspective view, an overall example according to the invention comprising a high-temperature SOEC / SOFC type stack and four guiding elements, [ Fig. 4B ] is an enlarged view along B1 of [ Fig. 4A ], [ Fig. 5 ] represents a detail of the making of a "V"-shaped notch on the stacking plates of [ Fig. 4A ], [ Fig. 6 ] is a detailed view of the fastening device on the lower support plate for stacking [ Fig. 4A ], [ Fig. 7 ] is a top view of [ Fig. 6 ], [ Fig. 8 ] represents, in front view, the lower end plate of the stack of [ Fig. 4A ], [ Fig. 9 ] represents, according to a perspective view, a guiding element of the whole of [ Fig. 4A ], [ Fig. 10 ] represents, according to a perspective view, a variant embodiment of a guiding element, [ Fig. 11 ] represents, from a perspective view, another example of an assembly according to the invention comprising a high-temperature SOEC / SOFC type stack and four guiding elements, in which elastic elements are used, [ Fig. 12 ] is a top view of [ Fig. 11 ], [ Fig. 13A ] represents, from a perspective view, an example of an elasticity element of the set of [ Fig. 11 ], [ Fig. 13B ] is a view according to B2 of [ Fig. 13A ], [ Fig. 14 ] illustrates, in perspective, the stacking of the lower terminal plate of a stack of an assembly according to the invention, [ Fig. 15 ] is a detailed view of [ Fig. 14 representing a fastening device, [ Fig. 16] et [Fig. 17 ] are detailed views allowing visualization of the manufacturing details of the fastening device, [ Fig. 18 ] represents, according to a perspective view, a variant embodiment of a guiding element, [ Fig. 19A ] represents, in perspective view, an upper support plate and four guide elements, [ Fig. 19B ] is an enlarged view along B3 of [ Fig. 19A illustrating a fastening device, [ Fig. 20A ] represents, in perspective view, a variant embodiment of an assembly according to the invention comprising a high-temperature SOEC / SOFC type stack and four guide elements, using the upper support plate of [ Fig. 19A ], And [ Fig. 20B ] is an enlarged view along B4 of [ Fig. 20A ].

[0057] Throughout these figures, identical references may designate identical or analogous elements.

[0058] Furthermore, the different parts represented in the figures are not necessarily shown on a uniform scale, in order to make the figures more legible. EXPOSÉ DÉTAILLÉ DE MODES DE RÉALISATION PARTICULIERS

[0059] THE figures 1 à 3 have already been described previously in the section relating to the prior art and the technical context of the invention. It is specified that, for the figures 1 et 2 The symbols and arrows for supplying water vapor H2O, distributing and recovering dihydrogen H2, oxygen O2, air and electric current, are shown for clarity and accuracy, to illustrate the operation of the devices shown.

[0060] Furthermore, it should be noted that all the components (anode / electrolyte / cathode) of a given electrochemical cell are preferentially ceramics. The operating temperature of a high-temperature SOEC / SOFC stack is also typically between 600 and 1000°C.

[0061] Furthermore, the possible terms "upper", "lower", "horizontal" and "vertical" are to be understood here according to the normal orientation of a SOEC / SOFC type stack when in its usage configuration.

[0062] THE figures 4A à 20B These illustrations demonstrate the principle of external guidance according to the invention. Compared to an internal guidance system for a stack, external guidance offers several advantages, particularly for tall stacks. Located at the periphery, it simplifies the integration of cooling circuit passages placed in the corners of the stacks. Furthermore, eliminating internal guide columns makes it easier to package multiple sub-stacks under the same press. Indeed, in a configuration incorporating internal guidance, once the stack has been reduced in height, the columns protrude from the upper end plate, preventing the placement of a second stack on top of it. For this reason, this type of internal guidance does not allow the simultaneous production of assemblies of several independent sub-stacks stacked one on top of the other on the same press bed.Furthermore, one of the advantages of external guidance according to the invention may also be the easy dismantling of the guide columns which allows a reduction in the size of the stack compared to internal guides and which opens up new possibilities for geometric configuration or internal design of the stacks.

[0063] Thus, the figures 4A à 9 relate to a first example of the realization of an assembly 80 according to the invention comprising a stack 20 of SOEC / SOFC type solid oxide cells operating at high temperature.

[0064] This stacking 20 consists of a plurality of plates P stacked one on top of the other along a vertical direction Z which is perpendicular to each of the plates P extended in horizontal planes parallel to the horizontal plane with axes X and Y, as seen on the figure 4A .

[0065] The stack 20 comprises a plurality of electrochemical cells C1, C2 as defined previously, here for example 100 electrochemical cells, each consisting of a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and a plurality of interconnectors 5 arranged between two adjacent electrochemical cells C1, C2. Furthermore, the stack 20 comprises an upper terminal plate 42 and a lower terminal plate 41, between which the plurality of electrochemical cells C1, C2 and the plurality of interconnectors 5 are sandwiched.

[0066] A plate P of the stack 20 can, for example, be formed by an electrochemical cell C1, C2, an interconnector 5, the upper terminal plate 42, the lower terminal plate 41, or even an insulating plate 25, for example made of mica, as can be seen on the figure 5 Each of these plates P has a top surface Sp, a bottom surface Si and an external lateral surface SI, represented in particular on the figure 5 The external lateral surface SI connects the upper surface Sp and the lower surface Si.

[0067] Furthermore, to achieve external guidance of the vertically stacked plates P, the assembly 80 according to the invention comprises four guide elements 11, 12, 13, 14, here in the form of guide columns. The number of these guide elements may be between 2 and 12, preferably being 4.

[0068] These guide columns 11, 12, 13 and 14 extend vertically along the vertical direction Z, bearing against the external lateral surface SI of each plate P. Thus, external guidance is achieved by bearing on the external face(s) of the stack.

[0069] In this example, each guide column 11, 12, 13, 14 has a cylindrical shape and a circular shape in cross-section with respect to the vertical direction Z, as can be seen for example on the figure 9 Alternatively, any other shape would be possible, including square or rectangular.

[0070] Furthermore, each plate P of stack 20 is substantially square in shape with a lateral surface SI, thus comprising four lateral faces. On each lateral face is formed a notch V1, V2, V3, V4 in which a guide column 11, 12, 13, 14 rests.

[0071] These four notches V1, V2, V3, and V4 are advantageously in the form of a "V," obtained by forming two tangent planes on the lateral face. Alternatively, any other shape is possible, notably circular or oval. It is also possible to have no notch formed on the P plates.

[0072] Thus, external guidance is achieved here by cylindrical column-type supports on flat edges. Specifically, the guidance is obtained by creating a support between a cylindrical face of a column and two tangent planes obtained by machining a "V" shaped notch.

[0073] As seen on the figures 5 And 8 Specifically, each notch V1, V2, V3, V4 has a "V" shape that defines an opening angle α between 15° and 60°. Advantageously, the same type of notch is used on all the plates P that make up stack 20. The number of notches used here is 4 to ensure guidance by an equivalent number of columns 11, 12, 13, 14. Alternatively, this number can be between 2 and 12.

[0074] Furthermore, the depth Pv of the "V" shape of each notch V1, V2, V3, V4, defined as the height of the "V", between the lateral surface SI and the union of the two tangent planes, as visible on the figure 8 The depth (Pv) is between 2 mm and 15 mm, with a typical depth of around 10 mm. This depth is adjustable according to the specific geometric constraints of the stack 20 and the desired guide height. Therefore, depending on the chosen depth (Pv), several guide column diameters can be considered while maintaining a geometry that ensures tangential support between the cylindrical surface and the bearing planes formed by the "V" machined on the edges of the plates (P). The position of the notches (V1, V2, V3, V4) can be freely chosen and adapted to the geometry of the plates (P), provided that each notch is preferably paired with another notch positioned in a substantially diametrically (or diagonally) opposite direction.

[0075] It should be noted that a shape other than a "V" can be used for all or part of the notches V1, V2, V3, V4, including a circular or oval shape. In particular, a circular shape can provide a single point of contact, thus reducing friction compared to a "V" shape. Advantageously, the diameter of the notch, or its largest transverse dimension, should also be greater than that of a guide post.

[0076] Furthermore, in order to ensure sufficient support contact while accommodating the coplanar movements of the plates P due to expansions during the manufacturing phase of the sealing glass-ceramic, it is advantageous to fix the guide columns 11, 12, 13, 14 by means of a fixing device 50 to a lower support plate 30 and / or an upper support plate 31.

[0077] More specifically, in order to ensure guidance with continuous support of the columns 11, 12, 13, 14 on the plates P without generating significant stresses that could cause them to buckle, the columns are mounted on at least one support plate 30, 31 with an interface enabling the following mechanical functions: maintaining the perpendicularity of the columns and their vertical locking; the translation of the columns in the axis of the movement of the faces of the stack; and the compression of the elastic elements bearing on the columns.

[0078] In this example of the figures 4A à 9 A fixing device 50 is provided at the base of each guide column 11, 12, 13, 14 to ensure the mechanical support of the column on the stack 20 by incorporating an elastic element, as visible on the figures 6 et 7 in particular. Each fixing device 50 is therefore fixed to the lower support plate 30 corresponding here to the support plate of the manufacturing bench, i.e. the manifold.

[0079] Thus, each fixing device 50 comprises a fixing base 51 or shoe, which is attached to the lower support plate 30, an elastic compression return element 52, here a compression spring (or alternatively a set of washers), one end of which is in contact with the guide column 11, 12, 13, 14 and the other end is in contact with the fixing base 51, and a fixing screw 53 mounted on the base 51, this fixing screw 53 allowing fixing and adjustment.

[0080] The majority of the vertical sagging movement of stack 20 observed during the glass-ceramic formation phase occurs within a temperature range of 650°C to 750°C. These temperatures, which are lower than the maximum temperature reached during the manufacturing cycle, allow the use of metallic compression springs 52 that retain sufficient mechanical properties to ensure a compressive force. Thus, compression springs 52 can, for example, be made of nickel-based metallic superalloys, such as Inconel® 718 or 750, which are used industrially for manufacturing springs for very high-temperature applications.Furthermore, the drastic drop in the elastic and mechanical properties of the spring material at temperatures above 750°C is not problematic in itself, since the stack 20 movements beyond this temperature are minimal, thus relieving the guiding stresses. Compression springs 52 can be of the single-use fusible type, maintaining their mechanical function at temperatures below 750°C. They can therefore be made of any material that retains good elastic properties and exhibits low creep at these temperatures. For example, compression springs 52 can also be made of Haynes® 230® type metallic superalloys, or even of ceramics, for example, produced through additive manufacturing.

[0081] In addition, in order for each guide column 11, 12, 13, 14 to be embedded and fixed in the lower support plate 30, or support plate of the manufacturing bench, or even also in the lower end plate 41, the column is also modified at its base.

[0082] Thus, as can be seen in particular on the figure 9 , each guide element 11, 12, 13, 14 includes a support device 60 cooperating with the fixing device 50. This support device 60 includes a support plane 61, of flattened shape, to allow the support of the compression spring 52, and a support base 62 which comes into contact with the lower support plate 30. In addition, the lower end of the column corresponds to a lower guide pin 64 on which a locking ring 65 of the circlip type is provided.

[0083] For this type of assembly, the position and relative clearances between the guide columns 11, 12, 13, 14 and the stack 20 plates P must be determined based on the expansion of the various assembly components. The material of a guide column can preferably be a material with the same coefficient of expansion as the stack 20, for example, a ferritic steel, such as VDM® Crofer or K41®, and preferably also the same material as the lower support plate 30 or the support plate of the manufacturing bench.

[0084] Advantageously, each guide column 11, 12, 13, 14 has the smallest possible point of contact to limit friction. To ensure this point of contact, the columns have a circular cross-section, as on the figure 9 , can be chosen. Alternatively, as illustrated by the figure 10 Triangular or, in this case, semi-triangular and semi-circular columns can be used. In this case, the column has a bearing edge 66 which can come into direct contact with the lateral surface SI of a plate P, without the need to form a notch on it.

[0085] Furthermore, the guidance can be implemented in such a way that the columns 11, 12, 13, 14 are held in place by means of an additional elastic element, as illustrated by the figures 11 à 13B .

[0086] Thus, two guide columns 11, 12 and 13, 14 can be held together by means of an elastic element, respectively 70 and 71 extending transversely with respect to the vertical direction Z.

[0087] These elasticity elements 70 and 71 can be chosen to retain their elasticity as high as possible and at least up to 750°C.

[0088] Thus, each elasticity element 70, 71 comprises a sliding bar 81, according to the double arrow F visible on the figure 13A , provided with an end 84 in the form of a mounting ring fixed to a column 12 or 13, and suitable for sliding inside a fixed bar 82, provided with an end 85 in the form of a mounting ring also fixed to another column 11 or 14.

[0089] These sliding bars 81 and fixed bars 82 are connected to each other by means of tension springs 83 mounted on pins 88 of these bars 81, 82.

[0090] Advantageously, these elastic elements 70, 71 help maintain the columns parallel to each other during stacking. They prevent or limit potential separation and deformation of the columns during stacking movements. They can be fusible and made of the same high-temperature material as the columns.

[0091] THE figures 14 à 17 illustrate the stacking of the lower end plate 41 on the lower support plate 30 and the fixing of the columns 11, 12, 13 and 14 on the lower support plate 30 by means of four fixing devices 50.

[0092] In addition to what has been described previously, we can see on the figure 15 that the lower support plate 30 has a counterbore 92 and a flat 91 to allow the guidance of the column and the base 51 or shoe. The base 51 ensures the perpendicularity of the column and the guide pin 64, machined to receive the circlip 65 (or any other equivalent, for example a pin or a clamping ring), is inserted into the counterbore 92 to ensure vertical locking, protruding beyond the thickness of the plate 30.

[0093] This assembly as illustrated in figures 14 à 17 This allows for the centering of the stack 20 on the bench, enabling the initial setup of the assembly to be aligned with the applied force. Perpendicularity is ensured by the base 62, and locking is achieved by the ring 65 mounted on the end of the column that protrudes from the plate 30. The guided translational movement of the column is achieved by the sliding of the base 62 within an oblong slot, or counterbore 92, machined in the plate 30. The retention and compression of the compression spring 52 are ensured by the mounting base 51, the position of which is laterally locked by the flat 91. The screw 53 allows adjustment of the compression level of the spring 52.

[0094] Assembly 80 is designed for assembling a stack 20 to provide guidance during a thermal cycle for forming the glass-ceramic seal. To enable its use in conditioning cycles that include powering up the stack, each column 11, 12, 13, 14 can be made of at least one electrically insulating material to prevent short-circuiting the different stack stages. Any insulating material can be used, such as a ceramic material, for example alumina, Macor®, among others, or a metallic material that becomes insulating after heating, such as aluminoforming, as well as any material that is initially conductive but covered with an insulating layer.

[0095] Preferably, each guide column 11, 12, 13, 14 can be made of VDM ®< Crofer to allow for coefficients of thermal expansion identical to those of stack 20 and can be covered with a layer of insulating material resistant to high temperatures, for example of yttria zirconia type.

[0096] Alternatively, each column 11, 12, 13, 14 can also be made in two parts as illustrated by the figure 18 . Thus, as an example, the column 11 may comprise a first part 11a made for example of alumina and a second metallic part 11b, the two parts being connected by a threaded, welded or brazed connection Lfb.

[0097] Furthermore, the fixing principle described above for the lower support plate 30 can also be applied to an upper support plate 31 as illustrated by the figures 19A à 20B for a stack 20 geometry of cylindrical type.

[0098] The upper support plate 31 includes a central base 95 of the support ball joint, and four fixing devices 50 for fixing the four guide columns 11, 12, 13 and 14.

[0099] In this cylindrical geometry of the stack 20, the columns can rest directly on the lateral surfaces SI of the plates P without requiring notches. With this type of support, larger column diameters can also be used. It should be noted that this type of configuration, placed on top of the stack 20 rather than attached to the lower support plate 30, can also be adapted to stacks with straight edges, as described previously.

Claims

1. An assembly (80) including: - a stack (20) of SOEC / SOFC-type solid-oxide cells operating at high temperature, consisting of a plurality of plates (P) stacked on top of one another according to a vertical direction (Z) substantially perpendicular to each horizontal plane of extent of each plate (P), each plate (P) including an upper surface (Sp), a lower surface (Si) and an outer lateral surface (SI), said plurality of plates (P) including at least: - a plurality of electrochemical cells (C1, C2) each formed by a cathode, an anode and an electrolyte interposed between the cathode and the anode, and a plurality of interconnectors (5) each arranged between two adjacent electrochemical cells (C1, C2), - an upper end plate (42) and a lower end plate (41), between which the plurality of electrochemical cells (C1, C2) and the plurality of interconnectors (5) are sandwiched, - at least two guiding elements (11, 12, 13, 14) ensuring guidance into a vertical stack of at least part of the plates (P) of the stack (20), characterized in that said at least two guiding elements (11, 12, 13, 14) extend vertically according to the vertical direction (Z) bearing against the outer lateral surface (SI) of each plate (P) of said at least part of the plates (P), wherein said at least two guiding elements (11, 12, 13, 14) are fastened by means of a fastening device (50) to a lower support plate (30) on which the stack (20) is placed and / or to an upper support plate (31) under which the stack (20) is placed, and the fastening device (50) includes a fastening base (51), secured to the lower support plate (30) and / or to the upper support plate (31), a compressive elastic return member (52), one end of which is in contact with a guiding element (11, 12, 13, 14) and the other end is in contact with the fastening base (51), and a fastening screw (53) mounted on the base (51).

2. The assembly according to claim 1, characterized in that the compressive elastic return member (52) is made of a metal alloy, in particular of a metal superalloy, in particular nickel-based, or made of ceramic, for example by additive manufacturing.

3. The assembly according to claim 1 or 2, characterized in that each guiding element (11, 12, 13, 14) includes a support device (60) cooperating with the fastening device (50), including at least one support plane (61) of the compressive elastic return member (52) and a support base (62) in contact with the lower support plate (30) and / or the upper support plate (31).

4. The assembly according to any one of the preceding claims, characterized in that said at least two guiding elements (11, 12, 13, 14) have at least partially a substantially cylindrical shape and having, in cross-section with respect to the vertical direction (Z), a substantially circular, triangular, triangular and semi-circular, square and / or rectangular shape.

5. The assembly according to any one of the preceding claims, characterized in that each plate (P) of said at least part of the plates (P) includes at least two notches (V1, V2, V3, V4) formed over the lateral surface (SI) of the plate (P) in which said at least two guiding elements (11, 12, 13, 14), in particular circular, oval or "V"-like shaped, bear.

6. The assembly according to claim 5, characterized in that each notch (V1, V2, V3, V4) of at least part of the notches (V1, V2, V3, V4) has a "V"-like shape obtained by forming two planes tangent on the lateral surface (SI) of the plate (P).

7. The assembly according to claim 6, characterized in that the "V"-like shape defines an angle (α) comprised between 15° and 60°.

8. The assembly according to claim 6 or 7, characterized in that the depth (Pv) of the "V"-like shape, defined as the height of the "V", between the lateral surface (SI) and the intersection of the two tangent planes, is comprised between 2 mm and 15 mm, in particular in the range of 10 mm.

9. The assembly according to any one of the preceding claims, characterized in that the number of said at least two guiding elements (11, 12, 13, 14) is comprised between 2 and 12, in particular equal to 4.

10. The assembly according to any one of the preceding claims, characterized in that said at least two guide elements (11, 12; 13, 14) are held secured together by means of at least one elastic element (70, 71) extending substantially transversally with respect to the vertical direction (Z).

11. The stack according to claim 10, characterized in that each elastic element (70, 71) includes a sliding element (81) provided with one end (84) fastened to a guiding element (11, 12, 13, 14), able to slide inside a fixed element (82), provided with one end (85) fastened to another guiding element (11, 12, 13, 14), the sliding (81) and fixed (82) elements being connected together by means of at least one tensile elastic return member (83).

12. The stack according to any one of the preceding claims, characterized in that said at least two guiding elements (11, 12, 13, 14) are made of at least one electrically-insulating material.

13. A method for conditioning a stack (20) of SOFC / SOFT-type solid-oxide cells operating at high temperature of an assembly (80) according to any one of the preceding claims, characterized in that it includes the step of guiding into a vertical stack at least part of the plates (P) making up the stack (20) by means of said at least two guiding elements (11, 12).