Interconnector for a stack of soec / sofc-type solid oxide cells having a perforated contact layer

Abstract

The main object of the invention is an interconnector (5) for a stack of SOEC / SOFC-type solid oxide cells, which is intended to be arranged between two adjacent electrochemical cells, is formed by the assembly of at least three plates (22, 23) which are elongated according to first and second axes of symmetry, the central plate (22) comprising openings (71, 72, 73, 74), each opening comprising tabs spaced apart from one another to form a comb and slots, characterized in that, of the first end plate and the second end plate (23), at least one is covered in the central portion with a contact layer (90), the surface area of which is greater than that of the central portion of the central plate, comprising at least one contact opening (92) elongated over a length (Lc) greater than the length (Lp) of the central portion and formed in superposition with at least one opening (71, 72, 73, 74) of the central plate (22).

Description

[0001] DESCRIPTION

[0002] Title: Interconnector for stacking of SOEC / SOFC type solid oxide cells comprising an openwork contact layer

[0003] TECHNICAL FIELD

[0004] 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 names "High Temperature Electrolysis" (HTE) and "High Temperature Steam Electrolysis" (HTSE), of the electrolysis of carbon dioxide (CO2), or even of the co-electrolysis of water vapor and carbon dioxide (CO2) at high temperature.

[0005] More specifically, the invention relates to the field of high-temperature solid oxide electrolysers, usually designated by the acronym SOEC (for “Solid Oxide Electrolysis Cell” in English).

[0006] 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).

[0007] Thus, more generally, the invention refers to the field of stacks of solid oxide cells of the SOEC / SOFC type operating at high temperature.

[0008] More specifically, the invention relates to an interconnector for a stack of solid oxide cells of the SOEC / SOFC type comprising at least one openwork contact layer, and a stack of solid oxide cells of the SOEC / SOFC type comprising a plurality of such interconnectors.

[0009] STATE OF THE PRIOR ART

[0010] In the context of a high-temperature solid oxide electrolyzer of the SOEC type, the aim is to transform, by means of an electric current, within the same electrochemical device, water vapor (H2O) into dihydrogen (H2) or other fuels such as methane (CH4), natural gas, biogas, and into dioxygen (O2), and / or to transform carbon dioxide (CO2) into carbon monoxide (CO) and dioxygen (O2). In the context of a high-temperature solid oxide fuel cell of the SOFC type, the operation is reversed to produce an electric current and heat by being supplied with dihydrogen (H2) and dioxygen (O2), typically air and natural gas, namely methane (CH4). For the sake of simplicity, the following description focuses on the operation of a high-temperature solid oxide electrolyzer of the SOEC type performing the electrolysis of water vapor.However, this operation is applicable to the electrolysis of carbon dioxide (CO2), or even to the co-electrolysis of high-temperature water vapor (HTE) with carbon dioxide (CO2). In addition, this operation can be transposed to the case of a high-temperature solid oxide fuel cell of the SOFC type.

[0011] To carry out the electrolysis of water, it is advantageous to carry it out 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 necessary for the reaction can be provided by heat, which is cheaper than electricity.

[0012] To implement high-temperature steam electrolysis (HTSE), a high-temperature solid oxide electrolyzer of the SOEC type consists of a stack of elementary patterns, each comprising a solid oxide electrolysis cell, or electrochemical cell, consisting of three anode / electrolyte / cathode layers superimposed on each other, and interconnection plates often made of metal alloys, also called bipolar plates or interconnectors. Each electrochemical cell is sandwiched between two interconnection plates. A high-temperature solid oxide electrolyzer of the SOEC type is then an alternating stack of electrochemical cells and interconnectors. A high-temperature solid oxide fuel cell of the SOFC type consists of the same type of stack of elementary patterns.Since 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.

[0013] Each electrochemical cell corresponds to an electrolyte / electrode assembly, which is typically a multi-layer ceramic assembly whose electrolyte is formed by a central ion-conducting layer, this layer being solid, dense and waterproof, and sandwiched between the two porous layers forming the electrodes. It should be noted that additional layers may exist, but these only serve to improve one or more of the layers already described.

[0014] The electrical and fluidic interconnection devices are electronic conductors which ensure, from an electrical point of view, the connection of each electrochemical cell of elementary pattern in the stack of elementary patterns, guaranteeing the electrical contact between one face and the cathode of a cell and between the other face and the anode of the following cell, and from a fluidic point of view, the supply of reactants and the evacuation of products for each of the cells. The interconnectors thus ensure the functions of supplying and collecting electric current and delimiting gas circulation compartments, for distribution and / or collection.

[0015] More precisely, the main function of the interconnectors is to ensure the passage of electric current but also the circulation of gases in the vicinity of each cell (namely: injected water vapor, hydrogen and oxygen extracted for EHT electrolysis; air and fuel including injected hydrogen and extracted water vapor for a SOFC cell), and to separate the anode and cathode compartments of two adjacent cells, which are the gas circulation compartments on the anode and cathode sides of the cells respectively.

[0016] In particular, for a high-temperature solid oxide electrolyzer of the SOEC type, the cathode compartment contains water vapor and hydrogen, the product of the electrochemical reaction, while the anode compartment contains a 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 oxidizer.

[0017] To carry out high-temperature steam electrolysis (HTE), water vapor (H2O) is injected into the cathode compartment. Under the effect of the electric current applied to the cell, the dissociation of water molecules in the form of vapor is carried out at the interface between the hydrogen electrode (cathode) and the electrolyte: this dissociation produces dihydrogen gas (H2) and oxygen ions (O 2). Dihydrogen (H2) is collected and discharged at the outlet of the hydrogen compartment. Oxygen ions (O 2 ) migrate through the electrolyte and recombine into oxygen (O2) at the interface between the electrolyte and the oxygen electrode (anode). A drain gas, such as air, can flow past the anode and thus collect the oxygen generated in gaseous form at the anode.

[0018] To operate a solid oxide fuel cell (SOFC), air (oxygen) is injected into the cathode compartment of the cell and hydrogen into the anode compartment. The oxygen in the air will dissociate into O ions 2- These ions will migrate in the electrolyte from the cathode to the anode to oxidize hydrogen and form water with simultaneous production of electricity. In SOFC cells, just like in SOEC electrolysis, the water vapor is in the dihydrogen (H2) compartment. Only the polarity is reversed.

[0019] For illustration purposes, 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:

[0020] 2 H2O -> 2 H2+ O2.

[0021] This reaction is carried out electrochemically in the cells of the electrolyser. As shown in Figure 1, each elementary electrolysis cell 1 is formed 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, electronically insulating and ionically conductive. The electrolyte 3 may in particular be an anionic conductor, more precisely an anionic conductor of O ions 2-and the electrolyser is then called an anionic electrolyser, as opposed to proton electrolytes (H + ).

[0022] Electrochemical reactions take place at the interface between each of the electronic conductors and the ionic conductor.

[0023] At cathode 2, the half-reaction is as follows:

[0024] 2 H2O + 4 e" -> 2 H2 + 2 O 2 '. At anode 4, the half-reaction is as follows:

[0025] 2 O O2+ 4 e;

[0026] Electrolyte 3, intercalated between the two electrodes 2 and 4, is the place of migration of the O ions 2- under the effect of the electric field created by the potential difference imposed between the anode 4 and the cathode 2.

[0027] As illustrated in parentheses in Figure 1, the water vapor at the cathode inlet may be accompanied by hydrogen H2 and the hydrogen produced and recovered at the outlet may be accompanied by water vapor. Similarly, as illustrated in dotted lines, a draining gas, such as air, may additionally be injected at the anode inlet to evacuate the produced oxygen. The injection of a draining gas has the additional function of acting as a thermal regulator.

[0028] 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 fluid distribution functions.

[0029] 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 supplies and gas supplies of the electrolyzer (electrolysis reactor).

[0030] A high-temperature solid oxide electrolyser of the SOEC type thus comprises at least one, generally a plurality of electrolysis cells stacked on top of each other, each elementary cell being formed of an electrolyte, a cathode and an anode, the electrolyte being interposed between the anode and the cathode.

[0031] As indicated previously, the fluidic and electrical interconnection devices which are in electrical contact with one or more electrodes generally provide the functions of supplying and collecting electric current and delimit one or more gas circulation compartments.

[0032] Thus, the so-called cathode compartment has the function of distributing the electric current and water vapor as well as recovering hydrogen at the cathode in contact.

[0033] The so-called anode compartment has the function of distributing the electric current as well as recovering the oxygen produced at the anode in contact, possibly using a draining gas.

[0034] Figure 2 represents an exploded view of elementary patterns 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 the cell C2 is shown), between which an electrolyte is arranged (only the electrolyte 3.2 of the cell C2 is shown).

[0035] The interconnector 5 is typically a metal alloy component that ensures the separation between the cathode 50 and anode 51 compartments, 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 ensures the distribution of gases to the cells. The injection of water vapor into each elementary pattern is done in the cathode compartment 50. The collection of the hydrogen produced and the residual water vapor at the cathode 2.1, 2.2 is carried out in the cathode compartment 50 downstream of the cell C1, C2 after dissociation of the water vapor by the latter. The collection of the oxygen produced at the anode 4.2 is carried out in the anode compartment 51 downstream of the cell C1, C2 after dissociation of the water vapor by the latter.The interconnector 5 ensures the passage of current between the cells C1 and C2 by direct contact with the adjacent electrodes, i.e. between the anode 4.2 and the cathode 2.1.

[0036] In current stack structures (a stack being a sandwich formed by the interconnectors and electrochemical cells placed between two rigid terminal plates, electrically insulated from the interconnectors), the dual function of the interconnectors for distributing gases and supplying electric current to the cells is ensured by contact layers, which are conductive metallic and / or ceramic structures, in particular ceramic structures of the strontium-doped lanthanum manganite (LSM) type, or even metallic grids.

[0037] For example, French patent application FR 2 996 065 A1 describes an interconnector in the form of a component with a metal alloy substrate, the basic element of which is Iron (Fe) or Nickel (Ni), with one of the main flat faces coated with a thick metal or ceramic contact layer, grooved to delimit channels suitable for the distribution and / or collection of gases, such as water vapor H2O, H2; O2, draining gas. In particular, a thick contact layer (whose thickness is greater than that of a layer obtained by a so-called "thin film" technology, typically a thickness of between 2 and 15 μm) made of strontium-doped lanthanum manganite (LSM) ceramic may be provided on the side of the oxygen electrode (anode in EHT, cathode for an SOFC cell).

[0038] The development of industrial systems integrating high-temperature solid oxide electrolyzers (SOECs) and solid oxide fuel cells (SOFCs) requires an increase in the volume of gas processed. This requires an increase in the surface area, the number of cells, and the number of interconnection plates per stack. The applied voltage and current levels must also be adjusted with the increase in the number of plates. Due to their structure, which has large surfaces subject to pressure, the pressurization level of high-temperature stacks remains limited. It is therefore necessary to optimize the structure of hydraulic networks to limit pressure losses. This optimization involves, in particular, reducing singular pressure losses within the stack.The transition zones located at the inlets and outlets of the anode and cathode chamber feeds are areas where optimization of geometries allows substantial gains in pressure loss.

[0039] To achieve increased production efficiency and good operating homogeneity of SOEC / SOFC solid oxide cell stacks operating at high temperatures, the role of interconnectors is essential, in particular to obtain good electrical contacts between the different parts of the stacks and also to allow good gas distribution within the electrochemical cells. The interconnectors can be metallic and composed of three thin plates, as described in French patent application FR 3 024985 A1.

[0040] Figure 3 thus represents, in an exploded view, an example of an interconnector 5 according to the prior art formed by the assembly of three thin metal sheets 21 to 23 assembled and laminated.

[0041] The three sheets 21, 22, 23 are elongated along two axes of symmetry X and Y orthogonal to each other, the sheets being laminated and assembled together by welding. A central sheet 22 is interposed between a first end sheet 21 and a second end sheet 23.

[0042] The central sheet 22 comprises a stamped central part 70 defining raised or stamped elements 10, and is pierced at the periphery of its central part 70, with four openings 71, 72, 73, 74. By “opening”, we mean a hole opening out on either side of a metal sheet.

[0043] One of the flat end sheets 21 comprises a flat central part 69 and is pierced, at the periphery of its central part 69, with four slots 61, 62, 63, 64. The first end sheet 21 further comprises two slots 67, 68, slots arranged symmetrically on either side of the Y axis. They are elongated over a length corresponding substantially to the length of the central part 69 along the Y axis.

[0044] The other of the flat end sheets 23 has a central part 89 which is hollowed out and pierced, at the periphery of its central part 89, with four openings 81, 82, 83, 84.

[0045] The slots 61, 71, 81, 63, 73, 83 of each sheet are elongated over a length corresponding substantially to the length of the central part 69, 70, 89 along the X axis, while the slots 62, 72, 82, 64, 74, 84 of each sheet are elongated over a length corresponding substantially to the length of the central part 69, 70, 89 along the Y axis.

[0046] The openings 71 to 74 of the central sheet 22 are widened respectively relative to the openings 61, 81, 62, 82, 63, 83, 64, 84, and they comprise in their widened part sheet metal tongues 710, 720, 730, 740 spaced from each other to form a comb. Each of the slots 711, defined between the edge of the widened opening 71 and a tongue 710 or between two successive tongues 710 opens onto the channels 11 defined by the reliefs 10 or stamped. The same applies to the slots made on the side of the openings 72, 73, 74.

[0047] The sheets 21, 22, 23 are typically made of ferritic steel with around 20% chromium, preferably CROFER® 22APU or FT18TNb, nickel-based Inconel® 600 or Haynes® type in thicknesses typically between 0.1 and 1 mm.

[0048] The choice to use metal grids for the contact layers, arranged on the interconnectors, is linked to a double technical and economic compromise. This type of structure, very simple to manufacture and low cost, allows, while ensuring the passage in its thickness, to distribute the gases homogeneously and to ensure a multitude of electrical contact points also distributed homogeneously over the entire cell. To improve fluidics by ensuring a sweep of the complete surface of the cell and to guarantee a good transfer of the current over the entire surface of the cell, the grids can be wider than the cell. On the edges of the grid, protruding from the cell, weld points are generally made to lock the latter in position on the interconnector.In this type of configuration, the grid covers the gas inlets / outlets, leading to a reduction in the flow section and an increase in the singular pressure drop in this area. The size of the grid can be identical to the size of the cell to limit the bending of the latter. On the other hand, in this configuration, part of the gas passes outside the useful area and reduces the maximum utilization rate of the sent gases.

[0049] In addition, the addition of glass in the grid, as described in French patent application FR 3 056 337 A1, makes it possible to guide the flow of gas used in the useful area.

[0050] To limit the pressure losses due to the passage of gas in the grid at the inlets and outlets, it is possible to reduce the size of the grid to the useful size of the cell, but cell bending problems arise. With a grid size the size of the useful area, it is also difficult to guide the gas only in the useful area. Indeed, a seal must be created between the edge of the grid and the cell, which is not easy. Also, there are still needs to optimize the interconnectors, particularly from a fluidic and mechanical point of view, and in particular to reduce the pressure losses occurring during the passage of gases.

[0051] STATEMENT OF THE INVENTION

[0052] The invention aims to at least partially remedy the needs mentioned above and the drawbacks relating to the achievements of the prior art.

[0053] It aims in particular to achieve an optimized design of interconnector for stacks of solid oxide cells of the SOEC / SOFC type, in particular by means of a geometry of the contact layers making it possible to improve the passage of gases in the chambers supplying the cells, by clearing the area located at the right of the inlets / outlets of the supply channels on the interconnectors.

[0054] The invention thus relates, according to one of its aspects, to an interconnector for a stack of solid oxide cells of the SOEC / SOFC type operating at high temperature, intended to be arranged between two adjacent electrochemical cells of the stack, each electrochemical cell being formed of a cathode, an anode and an electrolyte interposed between the cathode and the anode, the interconnector being formed by the assembly of at least three elongated plates along a first axis of symmetry and a second axis of symmetry orthogonal to each other, a central plate being interposed between a first end plate and a second end plate, the central plate comprising a central part and, at its periphery,at least two elongated slots over a length corresponding substantially to the length of the central part along the first axis of symmetry and two elongated slots over a length corresponding substantially to the length of the central part along the second axis of symmetry, each slot comprising tongues spaced from each other to form a comb and slots defined between the edge of a slot and a tongue or between two successive tongues, characterized in that at least one of the first end plate and the second end plate is covered in the central part with a contact layer with an electrochemical cell, the surface area of ​​which is greater than that of the central part of the central plate, and in particular that of an electrochemical cell,the contact layer comprising at least one contact lumen elongated over a length greater than the length of the central part along the first axis of symmetry and / or the second axis of symmetry and formed in at least partial superposition of at least one lumen of the central plate comprising tabs.,

[0055] The interconnector according to the invention may further comprise one or more of the following characteristics taken in isolation or in any possible technical combination.

[0056] Said at least one contact light of the contact layer can be obtained by different cutting methods, and in particular be laser cutting.

[0057] In addition, said contact layer may be a thick ceramic coating layer, porous or not, the ceramic material being chosen in particular from a lanthanum manganite of formula Lai- x Sr xMO3 with M (transition metals) = Nickel (Ni), Iron (Fe), Cobalt (Co), Manganese (Mn), Chromium (Cr), alone or in mixture, or materials with a lamellar structure such as lanthanide nickelates of formula Ln2NiO4 (Ln = Lanthanum (La), Neodymium (Nd), Praseodymium (Pr)), or another electrically conductive perovskite oxide.

[0058] Alternatively, said contact layer may be a thick metallic coating layer, the metallic material being chosen in particular from Nickel (Ni) and its alloys or chromino-forming alloys whose basic element is Iron (Fe).

[0059] Furthermore, the width of said at least one contact light may be greater than the width of the channel formed by the portion visible through said at least one contact light of the tabs of said at least one light.

[0060] In addition, the difference between the width of said at least one contact lumen and the width of the channel formed by the portion visible through said at least one contact lumen of the tabs of said at least one lumen may be greater than or equal to 2.5 mm.

[0061] A portion of said at least one of the first end plate and the second end plate and a portion of the tabs of said at least one lumen of the central plate may be visible through said at least one contact lumen.

[0062] Furthermore, the difference between the length of said at least one contact lumen and the length of the central portion of the central plate may be greater than or equal to 2.5 mm.

[0063] The distance between an edge of said at least one contact layer and said at least one contact lumen may be greater than or equal to 5 mm.

[0064] Furthermore, the ratio of the surface area of ​​said at least one contact layer to the surface area of ​​said central part of the central plate, in particular of an electrochemical cell, may be greater than or equal to 75%.

[0065] Furthermore, the invention also relates, according to another of its aspects, to a stack of solid oxide cells of the SOEC / SOFC type operating at high temperature, comprising 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 as defined previously, each arranged between two adjacent electrochemical cells.

[0066] BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The invention may be better understood by reading the detailed description which follows, non-limiting examples of its implementation, as well as by examining the schematic and partial figures of the attached drawing, in which:

[0068] [Fig. 1] is a schematic view showing the operating principle of a high-temperature solid oxide electrolyzer (SOEC),

[0069] [Fig. 2] is an exploded schematic view of a part of a high-temperature solid oxide electrolyser (SOEC) comprising interconnectors according to the prior art, [Fig. 3] is an exploded view of an interconnector for a stack of high-temperature SOEC / SOFC type solid oxide cells, corresponding to the assembly of three thin sheets or plates, [Fig. 4] is a partial perspective view from above of an example of an interconnector according to the invention, consisting of three thin sheets or plates, the central sheet comprising tabs,

[0070] [Fig. 5] is a partial top view of the interconnector of [Fig. 4], the second upper end plate being transparent,

[0071] [Fig. 6] is a detail view, from above and in perspective, of the interconnector of [Fig. 4] showing the flow of gases through a lumen of the contact layer,

[0072] [Fig. 7] is another detail view, from above, showing the geometry of a contact layer lumen, and

[0073] [Fig. 8] represents, in perspective and by observation from above, an assembly comprising a stack of solid oxide cells of the SOEC / SOFC type with interconnectors in accordance with the invention and a stack clamping system.

[0074] Throughout these figures, like references may designate identical or similar elements.

[0075] Furthermore, the different parts represented in the figures are not necessarily shown on a uniform scale, in order to make the figures more readable.

[0076] DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0077] Figures 1 to 3 have already been described previously in the section relating to the state of the prior art and the technical context of the invention. It is specified that, for Figures 1 and 2, the symbols and arrows for supplying water vapor H2O, distributing and recovering dihydrogen H2, oxygen O2, air and electric current are shown for the purposes of clarity and precision, to illustrate the operation of the devices shown.

[0078] Furthermore, it should be noted that all the constituents (anode / electrolyte / cathode) of a given electrochemical cell are preferably ceramics. The operating temperature of a high-temperature SOEC / SOFC stack is also typically between 600 and 1000°C. In addition, the possible terms “upper” and “lower” are to be understood here according to the normal orientation of a SOEC / SOFC stack when in its operating configuration.

[0079] An interconnector 5 according to the prior art has already been described previously with reference to FIG. 3. Identical elements will not be described again but remain within the scope of the invention.

[0080] Figures 4 to 7 partially illustrate an example of an interconnector according to the invention, comprising the three sheets 21, 22 and 23.

[0081] In this example, and in a non-limiting manner, the second end plate 23 is covered in the central part with a contact layer 90 intended to be interposed between the interconnector 5 and an electrochemical cell 1.

[0082] This contact layer 90 is for example a nickel grid in the hydrogen chamber.

[0083] The surface area of ​​the contact layer 90 is greater than that of the central part 70 of the central plate 22, and than that of an electrochemical cell 1.

[0084] Advantageously, the contact layer 90 comprises two slots 92, opposite on either side of the central part, elongated over a length L c greater than the length L p of the central part 70 along the first axis of symmetry X and formed in partial superposition respectively of the lights 71 and 73 of the central plate 22 comprising respectively the tabs 710 and 730.

[0085] In this contact layer 90, or contact grid, it is possible to deposit a layer of glass in order to ensure good distribution of the gases and to maximize the fuel utilization rates, as described in French patent application FR 3 056 337 A1. This provides the benefit of adding the glass described in this application and significantly reducing the singular pressure losses at the outlet of the clarinets.

[0086] Indeed, the lights 92 formed in the contact layer 90 constitute openings at the right of the inputs / outputs of the power supplies placed under the contact layer 90 allowing the passage of gases to be cleared and thus limiting the singular pressure losses created. Note that in figures 5 and 6, the arrows G represent the direction of circulation of the gases.

[0087] Advantageously, but not limited to, the openings 92 are laser cuts allowing the passage of gases to be cleared. Laser cutting allows for precision and avoids deformation of the strands and excess thicknesses. These cuts avoid the presence of wires above the gas supply channels and thus allow the passage section to be increased. Note that for a standard non-perforated contact layer, this restriction on the equivalent hydraulic diameter can represent up to 50% of the section (depending on the wire diameter, the mesh and the geometry of the channels).

[0088] Advantageously, the lights 92 in the form of cutouts are produced without modifying the external dimensions of the contact layer 90, thus making it possible to ensure electrical contact over the entire surface of the cell with a lateral overhang of the contact layer 90 sufficient to allow spot welding thereof, and the possible deposition of lateral glass as described in French patent application FR 3 056 337 A1.

[0089] It should also be noted that the constraints linked to the slots 92 in the form of cutouts are directly linked to the technical parameters of the contact layer 90, in particular the wire diameter and mesh parameters, and to the geometry of the channels of the interconnectors 5. If laser cutting of the contours of the contact layer 90 and the slots 92 does not pose any technical difficulties, to guarantee good mechanical strength of the contact layer 90 while avoiding the risks of the strands unraveling at the ends thereof, a minimum distance between the outer edge and the cutting zone is in particular between 5 and 10 times the mesh width. This minimum distance makes it possible to have a sufficient surface area for pointing the contact layer 90 on the interconnector 5.

[0090] Furthermore, to ensure good clearance of the contact layer 90 from the channels, the cutting width must slightly exceed the width of the channels. Thus, as seen in Figure 7, the width l c of each contact light 92 is greater than the width l a of the channel 71a, 73a formed by the portion visible through each contact light 92 of the tabs 710, 730 of the lights 71 and 73.

[0091] In particular, the difference between the width l c of each contact light 92 and the width l a of each channel 71a, 73a is greater than or equal to 2.5 mm.

[0092] Moreover, the difference between the length L c of each contact light 92 and the length L p of the central portion 70 of the central plate 22 is greater than or equal to 2.5 mm, and the distance between an edge of the contact layer 90 and a contact lumen 92 is greater than or equal to 5 mm.

[0093] Furthermore, 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, in particular of an electrochemical cell 1, is greater than or equal to 75%. In particular, for a cell of 100 cm 2 , the contact layer 90 will be 144 cm 2 .

[0094] It should be noted that compared to a contact layer of the prior art whose dimensions would be smaller, not covering the channels, the perforated contact layer 90 according to the invention makes it possible, without obstructing the gas supplies, to have an optimal support surface for the transfer of the compression forces applied to the stack, necessary for the transfer of current, and also makes it possible to increase the fuel utilization rate according to French patent application FR 3 056 337 A1. The cell being sandwiched between the contact layer 90 on one side and a network of LSM channels on the other, with a seal deposited on its periphery, a contact layer 90 providing external support to the mechanical contact zone of the cell limits the stresses on it.

[0095] Furthermore, Figure 8 represents a stack 20 of solid oxide cells of the SOEC / SOFC type operating at high temperature in accordance with the invention.

[0096] More specifically, FIG. 8 shows an assembly 80 comprising the stack 20 of solid oxide cells of the SOEC / SOFC type and a clamping system 60.

[0097] This assembly 80 has a structure similar to that of the assembly described in French patent application FR 3 045 215 A1.

[0098] The stack 20 comprises a plurality of electrochemical cells 1 each formed of a cathode, an anode and an electrolyte interposed between the cathode and the anode, and a plurality of interconnectors 5 according to the invention each arranged between two adjacent electrochemical cells 1. This set of electrochemical cells 1 and interconnectors 5 can also be referred to as a “stack”.

[0099] In addition, the stack 20 comprises an upper end plate 43 and a lower end plate 44, respectively also called upper stack end plate 43 and lower stack end plate 44, between which the plurality of electrochemical cells 1 and the plurality of interconnectors 5 are sandwiched, or between which the stack is located.

[0100] Furthermore, the assembly 80 also comprises a clamping system 60 for the stack 20 of solid oxide cells of the SOEC / SOFC type, comprising 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.

[0101] Each clamping plate 45, 46 of the clamping system 60 comprises four clamping holes 54. In addition, the clamping system 60 further comprises four clamping rods 55, or tie rods, extending through a clamping hole 54 of the upper clamping plate 45 and through a corresponding clamping hole 54 of the lower clamping plate 46 to allow the upper 45 and lower 46 clamping plates to be assembled together. The clamping system 60 further comprises clamping means 56, 57, 58 at each clamping hole 54 of the upper 45 and lower 46 clamping plates cooperating with the clamping rods 55 to allow the upper 45 and lower 46 clamping plates to be assembled together.More specifically, the clamping means comprise, at each clamping orifice 54 of the upper clamping plate 45, a first clamping nut 56 cooperating with the corresponding clamping rod 55 inserted through the clamping orifice 54. In addition, the clamping means comprise, at each clamping orifice 54 of the lower clamping plate 46, a second clamping nut 57 associated with a clamping washer 58, these cooperating with the corresponding clamping rod 55 inserted through the clamping orifice 54. The clamping washer 58 is located between the second clamping nut 57 and the lower clamping plate 46. Of course, the invention is not limited to the exemplary embodiments which have just been described. Various modifications may be made thereto by those skilled in the art.

Claims

CLAIMS 1. Interconnector (5) for a stack (20) of solid oxide cells of the SOEC / SOFC type operating at high temperature, intended to be arranged between two adjacent electrochemical cells (1) of the stack (20), each electrochemical cell (1) being formed of a cathode, an anode and an electrolyte interposed between the cathode and the anode, the interconnector (5) being formed by the assembly of at least three plates (21, 22, 23) elongated along a first axis of symmetry (X) and a second axis of symmetry (Y) orthogonal to each other, a central plate (22) being interposed between a first end plate (21) and a second end plate (23), the central plate (22) comprising a central portion (70) and, at its periphery, at least two slots (71, 73) elongated over a length corresponding substantially the length of the central part (70) along the first axis of symmetry (X) and two lights (72,74) elongated over a length corresponding substantially to the length of the central part (70) along the second axis of symmetry (Y), each light (71, 72, 73, 74) comprising tabs (710, 720, 730, 740) spaced from each other to form a comb and slots (711) defined between the edge of a light (71) and a tab (710) or between two successive tabs (711), characterized in that at least one of the first end plate (21) and the second end plate (23) is covered, at a central part (69, 89), with a contact layer (90) with an electrochemical cell (1), the surface area of ​​which is greater than that of the central part (70) of the central plate (22), and in particular that of an electrochemical cell (1), the contact layer (90) comprising at least one contact lumen (92) elongated over a length (L, c ) greater than the length (L p) of the central part (70) along the first axis of symmetry (X) and / or the second axis of symmetry (Y) and formed in at least partial superposition of at least one light (71, ni, 73, 74) of the central plate (22) comprising tabs (710, 720, 730, 740).

2. Interconnector according to claim 1, characterized in that said at least one contact lumen (92) of the contact layer (90) is a laser cut.

3. Interconnector according to claim 1 or 2, characterized in that said contact layer (90) is a thick ceramic coating layer, porous or not, the ceramic material being chosen in particular from a lanthanum manganite of formula Lai- x Sr xMO3 with M (transition metals) = Nickel (Ni), Iron (Fe), Cobalt (Co), Manganese (Mn), Chromium (Cr), alone or in mixture, or materials with a lamellar structure such as lanthanide nickelates of formula Ln2NiÜ4 (Ln = Lanthanum (La), Neodymium (Nd), Praseodymium (Pr)), or another electrically conductive perovskite oxide.

4. Interconnector according to claim 1 or 2, characterized in that said contact layer (90) is a thick metallic coating layer, the metallic material being chosen in particular from Nickel (Ni) and its alloys or chromino-forming alloys whose basic element is Iron (Fe).

5. Interconnector according to any one of the preceding claims, characterized in that the width (l c ) of said at least one contact light (92) is greater than the width (l a) of the channel (71a, 73a) formed by the portion visible through said at least one contact light (92) of the tabs (710, 720, 730, 740) of said at least one light (71, 72, 73, 74).

6. Interconnector according to any one of the preceding claims, characterized in that the difference between the width (l c ) of said at least one contact light (92) and the width (l a ) of the part of the channel (71a, 73a) which is visible through said at least one contact light (92) of the tabs (710, 720, 730, 740) of said at least one light (71, 72, 73, 74) is greater than or equal to 2.5 mm.

7. Interconnector according to any one of the preceding claims, characterized in that a part of said at least one of the first end plate (21) and the second end plate (23) and a part of the tabs (710, 720, 730, 740) of said at least one light (71, 72, 73, 74) of the central plate (22) are visible through said at least one contact light (92).

8. Interconnector according to any one of the preceding claims, characterized in that the difference between the length (L c ) of said at least one contact light (92) and the length (L p ) of the central part (70) of the central plate (22) is greater than or equal to 2.5 mm.

9. Interconnector according to any one of the preceding claims, characterized in that the distance between an edge of said at least one contact layer (90) and said at least one contact lumen (92) is greater than or equal to 5 mm.

10. Interconnector according to any one of the preceding claims, characterized in that the ratio of the surface area of ​​said at least one contact layer (90) to the surface area of ​​said central part (70) of the central plate (22), in particular of an electrochemical cell (1), is greater than or equal to 75%.

11. Stack (20) of solid oxide cells of the SOEC / SOFC type operating at high temperature, comprising a plurality of electrochemical cells (1) each formed of a cathode, an anode and an electrolyte intercalated between the cathode and the anode, and a plurality of interconnectors (5) according to any one of the preceding claims, each arranged between two adjacent electrochemical cells (1).

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