Interconnectors for stacks of solid oxide cells of the SOEC / SOFC type containing perforated contact layers

Abstract

The main subject of the present invention is an interconnector (5) for a stack of solid oxide cells of the SOEC / SOFC type, the interconnector (5) being intended to be placed between two adjacent electrochemical cells, the interconnector (5) being formed by assembling at least three elongated plates (22, 23) about a first and a second axis of symmetry, the central plate (22) comprising slots (71, 72, 73, 74), each slot comprising tabs and slits spaced apart so as to form a comb, in the interconnector (5), at least one of the first and second end plates (23) being covered in a central part by a contact layer (90), the surface area of ​​which is greater than the surface area of ​​the central part of the central plate, the contact layer (90) having a length (L) of the central part. p ) c ) and the at least one elongated contact slot (92) is formed to overlap with at least one slot (71, 72, 73, 74) of the central plate (22).

Description

[Technical Field]

[0001] The present invention relates to the general field of High Temperature Electrolysis (HTE), in particular High Temperature Steam Electrolysis (HTSE), carbon dioxide (CO2) electrolysis and also high temperature co-electrolysis of steam and carbon dioxide (CO2).

[0002] More specifically, the present invention relates to the field of high temperature solid oxide electrolysis cells (commonly referred to as SOECs).

[0003] It also relates to the field of high temperature solid oxide fuel cells (commonly referred to as SOFCs).

[0004] More generally, the invention therefore relates to the field of solid oxide cell stacks of the SOEC / SOFC type operating at high temperatures.

[0005] More specifically, the present invention relates to an interconnector for a stack of solid oxide cells of the SOEC / SOFC type comprising at least one perforated contact layer, and to a stack of solid oxide cells of the SOEC / SOFC type comprising a plurality of such interconnectors. [Background technology]

[0006] In the context of high-temperature solid oxide electrolysis cells (SOECs), it involves converting steam (H2O) to dihydrogen (H2) or other fuels (e.g., methane (CH4), natural gas, biogas, and dioxygen (O2)) and / or converting carbon dioxide (CO2) to carbon monoxide (CO) and dioxygen (O2) in the same electrochemical device by electric current. In the context of high-temperature solid oxide fuel cells (SOFCs), the operation is reversed, and current and heat are generated by supplying dihydrogen (H2) and dioxygen (O2) (typically found in air) and natural gas (i.e., with methane (CH4)). For simplicity, the following description focuses on the operation of high-temperature solid oxide electrolysis cells (SOECs) performing the electrolysis of steam. However, this operation is also applicable to the electrolysis of carbon dioxide (CO2) and even to the high-temperature co-electrolysis of steam (HTE) and carbon dioxide (CO2). In addition, this operation is transferable to the case of high-temperature solid oxide fuel cells (SOFCs).

[0007] To perform water electrolysis, it is advantageous to do so at high temperatures (typically between 600°C and 1000°C) because it is more advantageous to electrolyze steam rather 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 electrolysis cell of the SOEC type is composed of a stack of unit cells, each of which contains a solid oxide electrolysis cell (or electrochemical cell) (consisting of three anode / electrolyte / cathode layers stacked on top of each other) and an interconnection plate (also known as a bipolar plate or interconnector), often made of a metal alloy. Each electrochemical cell is clamped between two interconnection plates. The high-temperature solid oxide electrolysis cell of the SOEC type is then a stack of alternating electrochemical cells and interconnectors. A high-temperature solid oxide fuel cell of the SOFC type is composed of a stack of unit cells of the same type. Because this high-temperature technology is reversible, the same stack can operate in electrolysis mode, producing hydrogen and oxygen from water and electricity, or in fuel cell mode, producing electricity from hydrogen and oxygen.

[0009] Each electrochemical cell corresponds to an electrolyte / electrode assembly, which is typically a ceramic multilayer assembly, in which the electrolyte is formed by a central ionically conductive layer, which is solid, dense, and impermeable, and is clamped between two porous layers that form the electrodes. It should be noted that additional layers can be present, but are used only to strengthen one or more of the layers already described.

[0010] The electrical and fluidic interconnection device is an electronic conductor that, from an electrical point of view, ensures the connection of each unit electrochemical cell in the stack of unit cells, ensuring electrical contact between one side and the cathode of one cell and between the other side and the anode of the next cell, and, from a fluidic point of view, ensures the supply of reagents and the release of products for each of the cells. The interconnect thus serves the function of supplying and collecting current, and also defines the boundaries of gas flow compartments for distribution and / or collection.

[0011] More specifically, the main function of the interconnector is to ensure the flow of electrical current, but also the flow of gases in the vicinity of each cell (i.e.: injected steam, extracted hydrogen, and oxygen for HTE electrolysis; air and fuel (including injected hydrogen and extracted steam for SOFC cells)), and also to separate the anode and cathode compartments of two adjacent cells (which are the gas flow compartments on the anode and cathode sides of the cells, respectively).

[0012] In particular, for a high-temperature solid oxide electrolysis cell of the SOEC type, the cathode compartment contains steam and hydrogen (products of the electrochemical reaction), while the anode compartment contains drain gas (if present) and oxygen (another product of the electrochemical reaction).For a high-temperature solid oxide fuel cell of the SOFC type, the anode compartment contains the fuel, while the cathode compartment contains the oxidant.

[0013] To perform high-temperature steam electrolysis (HTE), steam (HO) is injected into the cathode compartment. Under the influence of an electric current applied to the cell, dissociation of water molecules in the form of steam takes place at the interface between the hydrogen electrode (cathode) and the electrolyte, which dissociation produces dihydrogen gas (H) and oxygen ions (O 2- ) is produced. Dihydrogen (H2) is collected and released at the hydrogen compartment outlet. Oxygen ions (O 2- ) migrates through the electrolyte and recombines into dioxygen (O) at the interface between the electrolyte and the oxygen electrode (anode). A drain gas (such as air) flows at the anode and can thus collect the oxygen evolved in gaseous form at the anode.

[0014] To ensure the operation of a solid oxide fuel cell (SOFC), air (oxygen) is injected into the cathode compartment of the fuel cell and hydrogen is injected into the anode compartment. The oxygen from the air is then mixed with O 2- The hydrogen dissociates into ions. These ions migrate through the electrolyte from the cathode to the anode, oxidizing the hydrogen and forming water with simultaneous electricity generation. In a SOFC fuel cell, similar to an SOEC electrolysis, vapor is found in the dihydrogen (H2) compartment. Only the polarity is reversed.

[0015] 1 is a schematic diagram showing the operating principle of a high temperature solid oxide electrolysis cell of the SOEC type. The function of such an electrolysis cell is to convert steam into hydrogen and oxygen according to the following electrochemical reactions: 2H2O → 2H2+ O2

[0016] This reaction is carried out electrochemically within the cells of the electrolysis cell. As shown schematically in FIG. 1, each unit electrolysis cell 1 is formed from a cathode 2 and an anode 4, which are 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 from porous materials, and the electrolyte 3 is impermeable to gases, an electronic insulator, and an ionic conductor. The electrolyte 3 can be, inter alia, an anion conductor, more specifically, O 2- The electrolytic cell can then be an anion conductor of protons (H + ) In contrast to electrolytes, they are called anionic electrolyzers.

[0017] The electrochemical reaction takes place at the interface between each of the electronic conductors and the ionic conductor.

[0018] At cathode 2, the half-reactions are: 2H2O + 4e - → 2H2 + 2O 2- .

[0019] At the anode 4, the half-reactions are: 2O 2- → O2+ 4e - .

[0020] The electrolyte 3 (interposed between the two electrodes 2 and 4) is charged to O under the influence of an electric field generated by a potential difference applied between the anode 4 and the cathode 2. 2- This is the site of iontophoresis.

[0021] As shown between brackets in Figure 1, the steam at the cathode inlet can be entrained by hydrogen H2, and the hydrogen produced and recovered at the outlet can be entrained by steam. Similarly, as shown by the dotted line, drain gas (e.g., air) can also be injected at the anode inlet to release the produced oxygen. Injecting the drain gas has the additional function of acting as a temperature regulator.

[0022] The unit electrolysis cell (or electrolysis reactor) consists of a unit cell as described above, with a cathode 2, an electrolyte 3, and an anode 4, and two interconnectors that perform the electrical and fluid distribution functions.

[0023] To increase the flow rate of hydrogen and oxygen produced, it is known to stack several unit electrolysis cells on top of each other (by separating them by interconnectors), the assembly being positioned between two end interconnect plates that support the power and gas supplies of the electrolysis cells (electrolysis reactors).

[0024] Thus, a high-temperature solid oxide electrolysis cell of the SOEC type comprises at least one (and generally several) electrolysis cells stacked on top of each other, each unit cell being formed from an electrolyte, a cathode and an anode, the electrolyte being interposed between the anode and the cathode.

[0025] As noted above, fluidic and electrical interconnection devices in electrical contact with one or more electrodes generally function to supply and collect electrical current and define one or more gas flow compartments.

[0026] The function of the cathode compartment is therefore to distribute the current and steam in contact with the cathode and also to recover the hydrogen.

[0027] The function of the anode compartment is to distribute the current to the anode in contact with it, and to recover the oxygen produced (optionally using a drain gas).

[0028] 2 shows an exploded view of a unit cell of a prior art SOEC-type high-temperature solid oxide electrolysis cell. The electrolysis cell includes multiple unit solid oxide electrolysis (SOEC)-type cells C1, C2 stacked alternately with interconnectors 5. Each cell C1, C2 consists of a cathode 2.1, 2.2 and an anode (only anode 4.2 of cell C2 is shown), with an electrolyte disposed between them (only electrolyte 3.2 of cell C2 is shown).

[0029] The interconnector 5 is typically a metal alloy component that ensures the separation between the cathode compartment 50 and the anode compartment 51, which are defined by the volume between the interconnector 5 and the adjacent cathode 2.1 and the volume between the interconnector 5 and the adjacent anode 4.2, respectively. It also ensures gas distribution to the cells. Steam is injected into each unit cell in the cathode compartment 50. Hydrogen produced in the cathodes 2.1 and 2.2 and residual steam in the cathodes 2.1 and 2.2 are collected in the cathode compartment 50 downstream of the cells C1 and C2 after dissociation of the steam by the cells C1 and C2. Oxygen produced in the anode 4.2 is collected in the anode compartment 51 downstream of the cells C1 and C2 after dissociation of the steam by the cells C1 and C2. The interconnector 5 ensures the flow of current between the cells C1 and C2 by direct contact with the adjacent electrodes, ie between the anode 4.2 and the cathode 2.1.

[0030] In the current stack structure (the stack is a sandwich structure formed by the interconnector and the electrochemical cells placed between two rigid terminal plates that are electrically insulated from the interconnector), the interconnector's dual function of gas distribution and current supply to the cells is fulfilled by contact layers, which are conductive metal and / or ceramic structures, in particular strontium-doped lanthanum manganite (LSM) ceramic structures or metal grids.

[0031] By way of example, French patent application No. 2996065 describes an interconnector in the form of a metal alloy substrate component, the base element of which is iron (Fe) or nickel (Ni), coated on one of its main planar faces by a thick metallic or ceramic contact layer, which is grooved by delimiting channels adapted to the distribution and / or collection of gases (for example steam HO, H2; O2, drain gas, etc.). In particular, a thick ceramic contact layer based on strontium-doped lanthanum manganite (LSM) (the thickness of which is greater than that of layers obtained by the so-called "thin layer" technique, typically between 2 μm and 15 μm thick) can be provided on the side of the oxygen electrode (anode in HTEs, cathode for SOFC fuel cells).

[0032] The development of industrial systems incorporating high-temperature solid oxide electrolysis cells (SOECs) and solid oxide fuel cells (SOFCs) involves an increase in the processed gas volume. To this end, it is necessary to increase the surface area and number of cells and interconnecting plates per stack. Furthermore, as the number of plates increases, the applied voltage and current levels must be adjusted. Due to their structure with a large surface area subjected to pressure, the level of pressurization of high-temperature stacks remains limited. To limit pressure losses, it becomes necessary to optimize the structure of the hydraulic network. This optimization involves, among other things, reducing singular head losses within the stack. The transition zones located at the feed inlet and outlet of the anode and cathode chambers are zones where geometric optimization allows for a significant increase in pressure loss.

[0033] To increase the production efficiency and obtain good homogeneity of operation of solid oxide cell stacks of the SOEC / SOFC type operating at high temperatures, the role of the interconnector is essential, in particular to obtain good electrical contact between the different parts of the stack and to allow good gas distribution inside the electrochemical cell. The interconnector can be made of metal and consist of three thin plates, as explained in French patent application no. 3024985.

[0034] Thus, Figure 3 shows in an exploded view an example of an interconnector 5 according to the prior art, formed by the assembly of three assembled and laminated thin metal sheets 21 to 23.

[0035] The three sheets 21, 22, 23 are elongated along two mutually perpendicular axes of symmetry X and Y, and are stacked and assembled together by welding. The central sheet 22 is inserted between the first end sheet 21 and the second end sheet 23.

[0036] The central sheet 22 includes a pressed central portion 70 defining the relief (or pressed) element 10, and is perforated at the periphery of the central portion 70 by four slots 71, 72, 73, 74. By "slots" is meant holes that pass through both sides of the metal sheet.

[0037] One of the planar end sheets 21 includes a planar central portion 69 that is perforated around the periphery of the central portion 69 by four slots 61, 62, 63, 64. The first end sheet 21 further includes two slits 67, 68, which are symmetrically disposed on either side of the Y-axis and are elongated along a length that substantially corresponds to the length of the central portion 69 along the Y-axis.

[0038] The other of the planar end sheets 23 includes a recessed central portion 89 that is perforated by four slots 81, 82, 83, 84 around the periphery of the central portion 89.

[0039] The slots 61, 71, 81, 63, 73, 83 in each sheet are elongated along a length that substantially corresponds to the length of the central portions 69, 70, 89 along the axis X, while the slots 62, 72, 82, 64, 74, 84 in each sheet are elongated along a length that substantially corresponds to the length of the central portions 69, 70, 89 along the axis Y.

[0040] The slots 71 to 74 of the central sheet 22 are wider relative to the slots 61, 81, 62, 82, 63, 83, 64, 84, respectively, and include, in their wider portions, sheet metal tabs 710, 720, 730, 740 spaced apart from one another forming combs. Each slit 711 defined between the edge of the widened slot 71 and the tab 710, or between two consecutive tabs 710, appears in a channel 11 defined by a relief element 10 or a pressed element. The same applies to the slits made on the sides of the slots 72, 73, 74.

[0041] The sheets 21, 22, 23 are typically made from ferritic steel with chromium of the order of 20%, preferably CROFER® 22APU or FT18TNb, which are based on nickel of the Inconel® 600 or Haynes® type, typically between 0.1 mm and 1 mm thick.

[0042] The choice of using a metal grid for the contact layer disposed on the interconnector is linked to a double technical and economic compromise. This type of structure, which is very simple to manufacture and low-cost, allows for homogeneous distribution of gas while ensuring flow throughout its thickness and allows for a large number of electrical contacts that are homogeneously distributed throughout the cell. To enhance the fluidic properties by ensuring complete coverage of the cell's surface area and to ensure good current transmission throughout the cell's surface area, the grid can be wider than the cell. At the edges of the grid that protrude from the cell, weld spots are typically created to lock the cell in place on the interconnector. In this type of configuration, the grid covers the gas inlet / outlet sections, reducing the flow cross-section and increasing the specific pressure loss in this zone. The size of the grid can be identical to the size of the cell, limiting its bending. However, in this configuration, some of the gas flows outside the usable zone, reducing the maximum utilization of the pumped gas.

[0043] Moreover, as explained in French patent application No. 3056337, the addition of glass in the grid makes it possible to guide the gas flow used in the usable zone.

[0044] To limit the pressure loss due to gas flow through the grid at the inlet and outlet, its size could be reduced to the usable size of the cells, but this would cause problems with cell bending. Also, with a grid size that is the size of the usable surface area, it would be difficult to guide the gas only within the usable zone. In fact, tightness would have to be created between the edges of the grid and the cells, which is not easy.

[0045] Therefore, there remains a need to optimize interconnectors, inter alia, from a fluidic and mechanical standpoint, and in particular to reduce the pressure losses that occur during gas flow. [Prior art documents] [Patent documents]

[0046] [Patent Document 1] French Patent Application No. 2996065 [Patent Document 2] French Patent Application No. 3024985 [Patent Document 3] French Patent Application No. 3056337 [Patent Document 4] French Patent Application No. 3045215 Summary of the Invention [Problem to be solved by the invention]

[0047] SUMMARY OF THE INVENTION It is an object of the present invention to at least partially remedy the above-mentioned needs and shortcomings associated with prior art embodiments.

[0048] In particular, it aims to generate an optimized interconnect design for stacks of solid oxide cells of the SOEC / SOFC type, with a contact layer geometry that makes it possible to improve the gas flow in the chambers supplying the cells, in particular by clearing zones located at the supply channel inlets / outlets on the interconnector. [Means for solving the problem]

[0049] The subject of the present invention is therefore, according to one of its aspects, an interconnector for a stack of solid oxide cells of the SOEC / SOFC type operating at high temperature, the interconnector being intended to be placed between two adjacent electrochemical cells of the stack, each electrochemical cell being formed from a cathode, an anode and an electrolyte interposed between the cathode and the anode, the interconnector being formed by assembling at least three elongated plates on first and second mutually perpendicular axes of symmetry, a central plate being interposed between a first end plate and a second end plate, the central plate comprising a central part and comprising, on its periphery, at least two elongated slots along a length substantially corresponding to the length of the central part on the first axis of symmetry and two elongated slots along a length substantially corresponding to the length of the central part on the second axis of symmetry, each slot comprising tabs spaced apart from one another to form a comb and slits defined between the edge of the slot and the tab or between two consecutive tabs, The interconnector is characterized in that at least one of the first end plate and the second end plate is covered in a central portion by a contact layer with the electrochemical cell, the surface area of ​​the contact layer being greater than the surface area of ​​the central portion of the central plate, in particular greater than the surface area of ​​the electrochemical cell, the contact layer including at least one elongated contact slot along a length greater than the length of the central portion at the first axis of symmetry and / or the second axis of symmetry, and the at least one elongated contact slot is formed to at least partially overlap at least one slot in the central plate including a tab.

[0050] The interconnector according to the invention may further comprise one or more of the following characteristics, taken individually or according to all possible technical combinations:

[0051] Said at least one contact slot in the contact layer can be obtained by different cutting methods, in particular it can be cut by a laser.

[0052] Moreover, the contact layer can be a thick, optionally porous, ceramic coating layer, the ceramic material being, inter alia, a compound of the formula La 1-x Sr x They are selected from lamellar structure materials such as lanthanum manganites of formula MO3 (where M (transition metal) = nickel (Ni), iron (Fe), cobalt (Co), manganese (Mn), chromium (Cr) alone or in mixtures), or lanthanide nickelates of formula Ln2NiO4 (Ln = lanthanum (La), neodymium (Nd), praseodymium (Pr)), or other conductive perovskite oxides.

[0053] Alternatively, the contact layer can be a thick metal coating layer, the metal material being selected, inter alia, from nickel (Ni) and its alloys or chromia-forming alloys, the base element of which is iron (Fe).

[0054] Additionally, the width of the at least one contact slot may be greater than the width of a channel formed by the portion of the tab of the at least one slot that is visible through the at least one contact slot.

[0055] Furthermore, the difference between the width of the at least one contact slot and the width of the channel formed by the portion of the tab of the at least one slot that is visible through the at least one contact slot can be 2.5 mm or more.

[0056] A portion of the at least one of the first and second end plates and a portion of a tab of the at least one slot in the center plate are visible through the at least one contact slot.

[0057] Moreover, the difference between the length of the at least one contact slot and the length of the central portion of the central plate may be greater than or equal to 2.5 mm.

[0058] The distance between the edge of the at least one contact layer and the at least one contact slot may be 5 mm or greater.

[0059] Moreover, the ratio of the surface area of ​​the at least one contact layer to the surface area of ​​the central portion of the central plate, in particular to the surface area of ​​the electrochemical cell, can be 75% or more.

[0060] Moreover, according to another of its aspects, the present invention further relates to a stack of solid oxide cells of the SOEC / SOFC type operating at high temperatures, the stack comprising a plurality of electrochemical cells and a plurality of interconnectors as defined above, the plurality of electrochemical cells each being formed from a cathode, an anode and an electrolyte interposed between the cathode and the anode, and the plurality of interconnectors being each positioned between two adjacent electrochemical cells.

[0061] The invention can be better understood by reading the following detailed description, by non-exhaustive examples of its implementation, and by studying the schematic and partial views of the accompanying drawings. [Brief explanation of the drawings]

[0062] [Figure 1] FIG. 1 is a schematic diagram illustrating the operating principle of a high-temperature solid oxide electrolysis cell (SOEC). [Figure 2] 1 is a schematic exploded view of a portion of a high temperature solid oxide electrolysis cell (SOEC) including an interconnector according to the prior art. [Figure 3] FIG. 1 shows an exploded view of an interconnector for a stack of high-temperature solid oxide cells of the SOEC / SOFC type, corresponding to an assembly of three thin sheets or plates. [Figure 4] FIG. 1 is a partial top perspective view of an example of an interconnector according to the present invention, which is composed of three thin sheets or plates, the central sheet including a tab. [Figure 5] FIG. 5 is a partial top view of the interconnector of FIG. 4, in which the second upper end plate is transparent. [Figure 6] FIG. 5 is a detailed top perspective view of the interconnector of FIG. 4, showing gas flow through the slots in the interface layer. [Figure 7] FIG. 10 is another detailed top view showing the geometry of the slots in the interface layer. [Figure 8] 1 shows a top perspective view of an assembly including a stack of solid oxide cells of the SOEC / SOFC type with an interconnector according to the invention and a system for clamping the stack. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0063] In all of these figures, the same reference numbers may designate the same or similar elements.

[0064] Moreover, the individual parts shown in the figures are not necessarily drawn to uniform scale in order to make the figures more readable.

[0065] Figures 1 to 3 have already been described above in the section relating to the prior art and the technical context of the present invention. With regard to Figures 1 and 2, it is specified that the symbols and arrows for distributing and recovering dihydrogen H, oxygen O, air, and electric current for supplying steam H, are shown for clarity and accuracy and illustrate the function of the device shown.

[0066] Moreover, it should be noted that all components (anode / electrolyte / cathode) of a given electrochemical cell are preferably ceramic. Moreover, the operating temperatures of high temperature SOEC / SOFC type stacks are typically between 600°C and 1000°C.

[0067] Moreover, the optional terms "upper" and "lower" are to be understood here according to the normal orientation of a stack of the SOEC / SOFC type when in its configuration for use.

[0068] The prior art interconnector 5 has already been described above with reference to Figure 3. Identical elements will not be described again but will remain within the scope of the present invention.

[0069] 4 to 7 partially illustrate an example of an interconnector according to the invention, which comprises three sheets 21, 22 and 23. In FIG.

[0070] In this example, in a non-limiting manner, the second end plate 23 is covered in the central part by a contact layer 90 intended to be interposed between the interconnector 5 and the electrochemical cell 1.

[0071] This contact layer 90 is, for example, a nickel grid in a hydrogen chamber.

[0072] The surface area of ​​the contact layer 90 is greater than the surface area of ​​the central portion 70 of the central plate 22 and greater than the surface area of ​​the electrochemical cell 1 .

[0073] Advantageously, the interface layer 90 includes two slots 92, which are opposite each other on either side of the central portion and extend along the length L of the central portion 70 at the first axis of symmetry X. p Length greater than L c , and are formed to overlap slots 71 and 73, respectively, in center plate 22, which include tabs 710 and 730, respectively.

[0074] In this contact layer 90 (or contact grid), a glass layer can be deposited to ensure good gas distribution and to maximize fuel utilization, as explained in French patent application No. 3056337. Thus, the benefits of adding glass as explained in this application are obtained, as well as a significant reduction in the specific pressure loss at the manifold outlet.

[0075] In fact, the slots 92 formed in the interface layer 90 form openings at the feed inlet / outlet sections located below the interface layer 90, allowing the gas flow to clear and thus limiting the differential pressure loss that is created. It should be noted that in Figures 5 and 6, the arrows G represent the direction of gas flow.

[0076] Advantageously, but not exclusively, the slots 92 are laser cut, which allows for clear gas flow. Laser cutting allows for precision and does not induce deformation and excessive thickness of the fibers. These cuts make it possible to prevent the presence of threads above the gas supply channels, thus increasing the flow cross section. It should be noted that for a standard, non-perforated contact layer, this limit on the hydraulic equivalent diameter can represent a maximum of 50% of the cross section (depending on the thread diameter, mesh, and channel geometry).

[0077] Advantageously, the cut-form slots 92 are produced without modifying the external dimensions of the contact layer 90, thus making it possible to ensure electrical contact over the entire surface area of ​​the cell with sufficient lateral projection of the contact layer 90 to allow its tack welding and, as explained in French patent application No. 3056337, optional lateral glass deposition.

[0078] It should also be noted that the constraints linked to the cut form of the slots 92 are directly linked to the technical parameters of the contact layer 90 (in particular the thread diameter and mesh parameters) and also to the geometry of the channels of the interconnector 5. If laser cutting the contours of the contact layer 90 and the slots 92 does not pose technical difficulties, the minimum distance between the outer edge and the cutting zone is, in particular, between 5 and 10 times the mesh width, in order to ensure good mechanical strength of the contact layer 90 by preventing the risk of fiber pull-out at the edge of the contact layer 90. This minimum distance makes it possible to have a sufficient surface area for tack welding the contact layer 90 onto the interconnector 5.

[0079] Moreover, to ensure good clearance of the contact layer 90 relative to the channel, the cutting width must slightly exceed the width of the channel. Thus, as can be seen in FIG. 7, the width l of each contact slot 92 c is the width l of the channels 71a, 73a formed by the portions of the tabs 710, 730 of the slots 71 and 73 that are visible through the contact slots 92, respectively. a is greater than.

[0080] In particular, the width l of each contact slot 92 c and the width l of each of the channels 71a and 73a a The difference between is 2.5 mm or more.

[0081] Additionally, the length L of each contact slot 92 c and the length L of the central portion 70 of the central plate 22 p is greater than or equal to 2.5 mm, and the distance between the edge of the contact layer 90 and the contact slot 92 is greater than or equal to 5 mm.

[0082] Moreover, the ratio of the surface area of ​​the contact layer 90 to the surface area of ​​the central portion 70 of the central plate 22, and in particular to the surface area of ​​the electrochemical cell 1, is 75% or more. 2For the cell, the contact layer 90 is 144 cm 2 This means that:

[0083] It should be noted that, in contrast to the contact layers of the prior art (which would have smaller dimensions and do not cover the channels), the perforated contact layer 90 according to the invention makes it possible to have an optimum bearing surface area to transmit the compressive forces applied to the stack, required for current transmission, without impeding the gas supply, and also makes it possible to increase the fuel utilization rate in accordance with French patent application No. 3056337. Since the cells are sandwiched between the contact layer 90 on one side and the LSM channel network on the other side, with a seal deposited on its periphery, the contact layer 90, which ensures external bearing in the mechanical contact zones of the cells, limits the stresses on the cells.

[0084] Moreover, FIG. 8 represents a stack 20 of solid oxide cells of the SOEC / SOFC type operating at high temperatures according to the invention.

[0085] More specifically, FIG. 8 shows an assembly 80 including a stack 20 of solid oxide cells of the SOEC / SOFC type and a clamping system 60 .

[0086] This assembly 80 has a structure similar to that of the assembly described in French patent application no. 3045215.

[0087] The stack 20 includes a plurality of electrochemical cells 1 and a plurality of interconnectors 5 according to the present invention, each of the plurality of electrochemical cells 1 being formed by a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and each of the plurality of interconnectors 5 being disposed between two adjacent electrochemical cells 1. This assembly of electrochemical cells 1 and interconnectors 5 may also be referred to as a "stack."

[0088] Moreover, the stack 20 includes an upper end plate 43 and a lower end plate 44, also referred to as the upper stack end plate 43 and the lower stack end plate 44, respectively, between which the plurality of electrochemical cells 1 and the plurality of interconnectors 5 are clamped, i.e., between which the stack is positioned.

[0089] Moreover, the assembly 80 also includes a system 60 for clamping the stack 20 of solid oxide cells of the SOEC / SOFC type, which includes an upper clamping plate 45 and a lower clamping plate 46 between which the stack 20 of solid oxide cells of the SOEC / SOFC type is clamped.

[0090] Each clamp plate 45, 46 of the clamp system 60 includes four clamp orifices 54. Moreover, the clamp system 60 further includes four clamp rods 55 (or tie rods) that extend through the clamp orifices 54 of the upper clamp plate 45 and through corresponding clamp orifices 54 of the lower clamp plate 46, allowing the upper clamp plate 45 and the lower clamp plate 46 to be assembled together. The clamp system 60 further includes clamping means 56, 57, 58 at the clamp orifices 54 of the upper clamp plate 45 and the lower clamp plate 46, respectively, that cooperate with the clamp rods 55 and allow the upper clamp plate 45 and the lower clamp plate 46 to be assembled together. More specifically, the clamping means includes, in each clamping orifice 54 of the upper clamping plate 45, a first clamping nut 56 which cooperates with a corresponding clamping rod 55 inserted through the clamping orifice 54. Additionally, the clamping means includes, in each clamping orifice 54 of the lower clamping plate 46, a second clamping nut 57 associated with a clamping washer 58 which cooperates with a corresponding clamping rod 55 inserted through the clamping orifice 54. The clamping washer 58 is positioned between the second clamping nut 57 and the lower clamping plate 46.

[0091] Naturally, the invention is not limited to the exemplary embodiments that have just been described, as various modifications can be made thereto by those skilled in the art. [Explanation of symbols]

[0092] 1. Electrolysis cell, electrochemical cell 2 cathodes 2.1 Cathode 2.2 Cathode 3 Electrolytes 3.2 Electrolytes 4 anodes 4.2 Anode 5 Interconnector 10 Relief Elements 11 channels 20 stacks 21 first end sheet, first end plate 22 Center Plate 23 second end sheet, second end plate 43 Upper end plate, upper stack end plate 44 Lower end plate, lower stack end plate 45 Upper clamp plate 46 Lower clamp plate 50 cathode compartment 51 Anode Compartment 54 Clamp Orifice 55 Clamp rod 56 First clamp nut 57 Second clamp nut 58 Clamp washer 60 Clamping System 61 slots 62 slots 63 Slots 64 slots 67 Slit 68 Slit 69 Central part 70 central part 71 Slots Channel 71a 72 slots 73 Slots Channel 73a 74 slots 80 Assembly 81 Slots 82 slots 83 Slots 84 slots 89 Central part 90 Contact layer 92 slots 710 Sheet Metal Tab 711 Slit 720 Sheet Metal Tab 730 Sheet Metal Tab 740 Sheet Metal Tab Cell C1 C2 cell G Gas flow direction L c Length of contact slot 92 L p Length of central part 70 l a Width of channels 71a, 73a l c Contact slot 92 width

Claims

1. An interconnector (5) for a stack (20) of solid oxide cells of the SOEC / SOFC type operating at high temperatures, the interconnector (5) intended to be placed between two adjacent electrochemical cells (1) of the stack (20), each electrochemical cell (1) being formed from a cathode, an anode and an electrolyte interposed between the cathode and the anode, the interconnector (5) being formed by assembling at least three elongated plates (21, 22, 23) on mutually orthogonal first and second axes of symmetry (X, Y), a central plate (22) being interposed between the first end plate (21) and the second end plate (23), an interconnector (5) in which the central plate (22) comprises a central portion (70) and at its periphery at least two elongated slots (71, 73) along a length substantially corresponding to the length of the central portion (70) in the first axis of symmetry and two elongated slots (72, 74) along a length substantially corresponding to the length of the central portion (70) in the second axis of symmetry (Y), each slot (71, 72, 73, 74) comprising tabs (710, 720, 730, 740) spaced apart from one another to form a comb, and slits (711) defined between the edges of the slots (71) and the tabs (710) or between two consecutive tabs (711), At least one of the first end plate (21) and the second end plate (23) is covered in its central portion (69, 89) by a contact layer (90) with the electrochemical cell (1), the surface area of ​​the contact layer (90) being greater than the surface area of ​​the central portion (70) of the central plate (22), in particular greater than the surface area of ​​the electrochemical cell (1), and the contact layer (90) is formed over a length (L) of the central portion (70) along the first axis of symmetry (X) and / or the second axis of symmetry (Y). ｐ ) ｃ ) along said at least one elongated contact slot (92), said at least one elongated contact slot (92) being formed to at least partially overlap at least one of said slots (71, 72, 73, 74) of said central plate (22) including said tabs (710, 720, 730, 740).

2. 2. The interconnector (5) according to claim 1, characterized in that the at least one contact slot (92) in the contact layer (90) is cut by a laser.

3. The contact layer (90) is a thick, optionally porous, ceramic coating layer, the ceramic material being, inter alia, of the formula La １－ｘ Sr ｘ MO ３ Lanthanum manganites of the formula Ln ２ NiO ４ 3. The interconnector (5) according to claim 1 or 2, characterized in that it is selected from lamellar structure materials such as lanthanide nickelates (Ln = lanthanum (La), neodymium (Nd), praseodymium (Pr)) or other conductive perovskite oxides.

4. 3. The interconnector (5) according to claim 1 or 2, characterized in that the contact layer (90) is a thick metal coating layer, the metal material being selected in particular from nickel (Ni) and its alloys or chromia-forming alloys, the base element of which is iron (Fe).

5. The width (l) of said at least one contact slot (92) ｃ ) is the width (l) of the channel (71a, 73a) formed by the portion of the at least one slot (71, 72, 73, 74) of the tab (710, 720, 730, 740) that is visible through the at least one contact slot (92). ａ 5. The interconnector (5) according to claim 1, wherein the thickness of the first electrode is greater than 1 / 2 mm.

6. The width (l) of the at least one contact slot (92) ｃ ) and the width (l) of the portion of the channel (71a, 73a) visible through the at least one contact slot (92) of the tab (710, 720, 730, 740) of the at least one slot (71, 72, 73, 74). ａ 6. The interconnector (5) according to claim 1, wherein the difference between the first and second electrodes is 2.5 mm or more.

7. 7. The interconnector (5) according to claim 1, wherein a portion of at least one of the first end plate (21) and the second end plate (23) and a portion of the tabs (710, 720, 730, 740) of the at least one slot (71, 72, 73, 74) of the central plate (22) are visible through the at least one contact slot (92).

8. The length (L) of the at least one contact slot (92) ｃ ) and the length (L ｐ 8. The interconnector (5) according to any one of claims 1 to 7, characterized in that the difference between the thicknesses of the first and second electrodes is 2.5 mm or more.

9. 9. The interconnector (5) according to any one of claims 1 to 8, characterized in that the distance between the edge of the at least one contact layer (90) and the at least one contact slot (92) is 5 mm or more.

10. 10. The interconnector (5) according to any one of claims 1 to 9, characterized in that the ratio of the surface area of ​​the at least one contact layer (90) to the surface area of ​​the central portion (70) of the central plate (22), in particular to the surface area of ​​the electrochemical cell (1), is 75% or more.

11. 11. A stack (20) of solid oxide cells of the SOEC / SOFC type operating at high temperatures, the stack (20) comprising a plurality of electrochemical cells (1) and a plurality of interconnectors (5) according to any one of claims 1 to 10, wherein the plurality of electrochemical cells (1) are each formed of a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and the plurality of interconnectors (5) are each arranged between two adjacent electrochemical cells (1).

Images