Power supply conductor and connection device for SOEC / SOFC type stacking

Abstract

The invention relates to an electrical connection device (100) between a power supply conductor (60) and a stack (20) of high-temperature SOEC / SOFC type solid oxide cells, comprising such a stack (20) and at least one power supply conductor (60) comprising a conductor body (61) and a fastening portion (64) for attachment to the upper terminal plate (43) and / or the lower terminal plate (44), characterized in that the conductor body (61) has a fastening end (61f) extending along a vertical axis (X) perpendicular to the first (P1) and second (P2) horizontal planes of the terminal plates (43, 44), and in that the fastening portion (64) of said at least one power supply conductor (60) is located at the end and in the axial extension, along the vertical axis (X), of the fastening end (61f) of the conductor body (61). Figure for the abstract: Figure 7A

Description

Title of the invention: Connection device between power supply conductor and SOEC / SOFC type stack. TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the general field of high temperature water 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 co-electrolysis of high temperature water (HTE) with 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 Electrolyzer Cell" in English).

[0003] It also relates to 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 electrical connection device between a power supply conductor and a stack of SOEC / SOFC type solid oxide cells operating at high temperature. STATE OF THE ART

[0006] In a high-temperature solid oxide electrolyzer (SOEC), the process involves transforming water vapor (H2O) into dihydrogen (H2) and dioxygen (O2) by means of an electric current within the same electrochemical device, and / or transforming carbon dioxide (CO2) into carbon monoxide (CO) and dioxygen (O2). In a high-temperature solid oxide fuel cell (SOFC), the operation is reversed, producing an electric current and heat when 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 (SOEC) performing water electrolysis.However, this principle is applicable to the electrolysis of carbon dioxide (CO2), and even to the co-electrolysis of water at high temperature (EHT) 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 carry it out at high temperature, typically between 600°C and 1000°C, and preferably between 650°C and 850°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 water electrolysis (HTW), 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 anode / electrolyte / cathode layers stacked one on top of the other, 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 of the SOEC type is thus an alternating stack of electrochemical cells and interconnectors. A high-temperature solid oxide fuel cell (SOFC) of the SOEC type consists of the same type of stack of elementary units.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.

[0009] Each electrochemical cell corresponds to an electrolyte / electrode assembly, which is typically a multilayer ceramic assembly in which the electrolyte is formed by a central ion-conducting layer. This layer is solid, dense, and impermeable, and is sandwiched between the two porous layers forming 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] The electrical and fluidic interconnection devices are electronic conductors that ensure, from an electrical point of view, the connection of each electrochemical cell of elementary pattern in 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, and from a fluidic point of view, thus combining the output of each of the cells. The interconnectors thus ensure the functions of supplying and collecting electrical current and delimit 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, hydrogen and oxygen extracted for EHT electrolysis; air and fuel including injected hydrogen and extracted water vapor) for an SOFC), and to separate 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 oxidizer.

[0013] To perform high-temperature steam electrolysis (HTE), steam (H2O) is injected into the cathode compartment. Under the effect of the electric current applied to the cell, the dissociation of water molecules into vapor 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 of the cell 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 dihydrogen (H2) compartment. Only the polarity is reversed.

[0015] By way of illustration, [Fig. 1] shows a schematic view illustrating 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:

[0016] 2 H2O 2 H2 + O2.

[0017] This reaction is carried out electrochemically in the cells of the electrolyzer. As shown schematically in [Fig. 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, electronic insulator and ionic conductor. 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 protonic electrolytes (H+).

[0018] The electrochemical reactions take place at the interface between each of the electronic conductors and the ionic conductor.

[0019] At cathode 2, the half-reaction is as follows:

[0020] 2H2O + 4 é -> 2H2 + 2 O2.

[0021] At anode 4, the half-reaction is as follows:

[0022] 2 O2 —> O2+4 e .

[0023] The electrolyte 3, intercalated between the two electrodes 2 and 4, is the site of migration of the O2 ions under the effect of the electric field created by the potential difference imposed between the anode 4 and the cathode 2.

[0024] As illustrated in parentheses in [Fig. 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 dashed line, a draining gas, such as air, may also be injected at the inlet to remove the oxygen produced. The injection of a draining gas has the additional function of acting as a thermal regulator.

[0025] 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, hydraulic and thermal distribution functions.

[0026] To increase the flow rates of hydrogen and oxygen produced, it is known to stack several elementary electrolysis cells one on top of the other, separating them with interconnectors. The assembly is positioned between two end interconnection plates that support the electrical and gas supplies of the electrolyzer (electrolysis reactor).

[0027] A high-temperature solid oxide electrolyzer of the SOEC type thus comprises at least one, generally 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.

[0028] As previously stated, the fluid and electrical interconnection devices which 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.

[0029] 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.

[0030] 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.

[0031] Figure 2 shows an exploded view of elementary motifs of an electrolyzer high-temperature solid oxide type SOEC according to the prior art. This electrolyzer comprises a plurality of elementary electrolysis cells Cl, C2, of the solid oxide type (SOEC), stacked alternately with interconnectors 5. Each Cl, C2 cell 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).

[0032] The interconnector 5 is a metal alloy component that provides the separation between the cathodic compartment 50 and 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 ensures the distribution of gases to the cells. The injection of water vapor into each elementary motif takes place in the cathodic 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 cathodic compartment 50 downstream of the cell Cl, C2 after the water vapor has been dissociated by the latter. The collection of the oxygen produced at the anode 4.2 is carried out in the anodic compartment 51 downstream of the cell Cl, C2 after the water vapor has been dissociated by the latter.Interconnector 5 ensures the passage of current between cells Cl and C2 by direct contact with adjacent electrodes, i.e. between the anode 4.2 and the cathode 2.1. .

[0033] Since the operating conditions of a high-temperature solid oxide electrolyzer (SOEC) are very close to those of a solid oxide fuel cell (SOFC), the same technological constraints are found.

[0034] Thus, the proper functioning of such SOEC / SOFC type solid oxide stacks operating at high temperature mainly requires compliance with the points stated below.

[0035] First, electrical insulation is necessary between two successive interconnectors to avoid short-circuiting the electrochemical cell. Good electrical contact and a sufficient contact surface between a cell and an interconnector are also required. The lowest possible ohmic resistance is sought between cells and interconnectors.

[0036] Furthermore, a seal must be provided between the anodic and cathodic compartments, otherwise there will be a recombination of the gases produced, leading to a decrease in efficiency and, above all, the appearance of hot spots damaging the stack.

[0037] Furthermore, it is essential to have a good distribution of gases both in the inlet and in the recovery of the products under penalty of loss of yield, inhomogeneity of pressure and temperature within the different elementary motifs, or even of prohibitive degradation of the electrochemical cells.

[0038] Finally, it is necessary to carefully control the gas inlet temperature to limit thermomechanical stresses in the electrochemical cell. In particular, it is desirable that the gas inlet temperature be very close to the cell's operating temperature. This is especially important since the electrochemical cell is composed of ceramic elements that are sensitive to temperature gradients.

[0039] The gases entering and exiting a high-temperature SOEC or SOFC stack operating at high temperature can be managed by means of suitable devices of a furnace such as that illustrated with reference to [Fig.3].

[0040] The furnace 15 thus comprises cold sections PF and hot sections PC, the latter including in particular the furnace floor 11, a loop tube 12 for managing gas inlets and outlets, and the high-temperature electrolysis (SOEC) or fuel cell (SOFC) stack 20. It should be noted that, in this [Fig. 3], the upper part located above the furnace floor 11 has only been partially shown in order to visualize the stack 20 and the loop tube 12. Also, although not visible here, the hot sections PC also include insulation and heating means.

[0041] A stack formed from a set of electrochemical cells and interconnectors can also be referred to by the English term "stack". There are usually between 25 and 1000, and typically about 75, electrochemical cells in a stack.

[0042] Furthermore, [Fig. 4] illustrates an example of such a stack 20, shown here with a clamping system comprising upper clamping plates 45 and lower clamping plates 46. The stack 20 comprises a plurality of electrochemical cells 41, each consisting of a cathode, an anode, and an electrolyte interposed between the cathode and the anode, and a plurality of intermediate interconnectors 42, each arranged between two adjacent electrochemical cells 41. In addition, it comprises an upper terminal plate 43 and a lower terminal plate 44, also referred to respectively as the upper stack terminal plate 43 and the lower terminal plate of the stack. lower stack 44, between which the plurality of electrochemical cells 41 and the plurality of intermediate interconnectors 42 are enclosed, i.e. between which the stack is located.

[0043] To operate, a stack must be supplied with gas and electrical current. The gas supply is achieved by placing the stack on a manifold, and the electrical supply is achieved by connecting the stack to a power supply that allows current to flow between the upper terminal plate 43 and the lower terminal plate 44. The greater the number of intermediate interconnectors 42 constituting the stack 20, the greater the power to be supplied, or produced in stack mode. For stacks 20 with several dozen interconnectors 42, conductors with electrical connections capable of carrying high current levels at high temperatures are required.

[0044] The power supply to a stack 20 is illustrated, by way of example, in [Fig. 5]. It is achieved by connecting electrical connectors 60 to the upper and lower parts of the stack 20, which are fixed either directly to the upper terminal plates 43 and lower terminal plates 44 (as in [Fig. 5]), or to a cover-type part, or upper cover (not shown), and the lower terminal plate 44. These electrical connectors 60, one of which is shown separately in [Fig. 6], are commonly called "current rods" because of their curved shape. They allow the passage of high current levels, on the order of several hundred amperes.

[0045] By way of example, the Applicant's patent application EP 3 098 889 A1 describes a mechanical concept for manufacturing such current rods. According to this concept, to reconcile the constraints related to the high operating temperature, the high current level, and the mechanical integration of the connectors, the current rods consist of a conductor made of a nickel-based superalloy tube of the Inconel® type, inside which a copper bar is welded by hot isostatic pressing, and to the end of which a fixing tab, also made of Inconel®, is welded. The electrical connection of the current rods is ensured by a bolted assembly that secures the connection flange located at the end of the current rod to the lower or upper terminal plate, or a cover.

[0046] In [Fig. 5], a current rod 60 can be seen directly attached to the upper terminal plate 43 and another current rod 60 directly attached to the lower terminal plate 44. In [Fig. 6], a current rod 60 can be seen comprising a rod body 61 made of an Inconel® sheath with a copper core, an Inconel® connection flange 62, and a screw / nut fastening connection 63. The structure of the rod body 61, with a conductive copper core embedded in an Inconel® sheath, allows the passage of high current levels Electrically, by limiting ohmic losses and therefore heating, the Inconel® casing protects the copper from oxidation. Under high-temperature operating conditions, the copper is exposed to atmospheric oxygen and can be severely degraded.

[0047] One of the drawbacks of this known principle lies in the electrical connection of the current rod 60 to the upper end plates 43 and lower end plates 44. This connection, which generates significant local electrical losses, imposes assembly constraints. The lower electrical conductivity of the Inconel® connecting flange located at the end of the current rod 60, combined with the electrical losses generated by the bolted connection, leads to the formation of a heating zone when high electrical currents pass through it. This hot spot, localized when the electrical connection deteriorates, can lead to significant damage to the stack 20 and the end plates 43, 44. The installation and tightening of this mechanical connection also require the implementation of an assembly procedure involving surface preparation, the use of appropriately sized fasteners (screws, nuts, washers), and tightening to a controlled torque.This type of assembly is also susceptible to loosening during thermal cycling. These loosenings significantly degrade the conductivity of the connection and can lead to disastrous consequences.

[0048] Thus, there is still a need to design alternative assemblies to make the electrical connections of the current supplies on the terminal plates of a stack. Description of the invention

[0049] The invention aims to remedy at least partially the needs mentioned above and the disadvantages relating to the achievements of the prior art.

[0050] The invention has in particular the objective of proposing an electrical connection solution improving the integration and compactness of the stack, by positioning the current leads inside the structure of the stack.

[0051] The invention thus relates, according to one of its aspects, to an electrical connection device between a power supply conductor and a stack of SOEC / SOFC type solid oxide cells operating at high temperature, comprising:

[0052] - a stack of SOEC / SOFC type solid oxide cells operating at high temperature, comprising:

[0053] - a plurality of electrochemical cells, each consisting of a cathode, a anode and an electrolyte intercalated between the cathode and the anode,

[0054] - a plurality of intermediate interconnectors arranged each between two cells adjacent electrochemical cells,

[0055] - an upper end plate and a lower end plate between in which the plurality of electrochemical cells and the plurality of intermediate interconnectors are enclosed, the upper terminal plate and the lower terminal plate extending substantially respectively in a first horizontal plane and in a second horizontal plane, parallel to each other,

[0056] - at least one power supply conductor, comprising:

[0057] - a conductor body,

[0058] - a portion of the fastener, for the fastening of said at least one conductor power supply to the upper terminal plate and / or the lower terminal plate,

[0059] characterized in that the conductor body of said at least one power supply conductor comprises a fixing end extending along a vertical axis, perpendicular to the first and second horizontal planes,

[0060] and in that the portion of the fixing of said at least one power supply conductor is located at the end and in the axial extension, along the vertical axis, of the fixing end of the conductor body.

[0061] Thanks to the invention, it is possible to provide electrical current without using external connections fastened by bolts, as per the prior art, thereby avoiding or limiting the problems generated by this type of mechanical connection, which is detrimental with regard to the local electrical losses generated. The introduction of a straight conductor through the stack structure allows for a connection perpendicular to the terminal plates. The usual connecting bracket and bolts can be replaced by a more direct mechanical connection that does not require the use of additional parts, such as nuts and bolts.

[0062] The device according to the invention may further comprise one or more of the following characteristics taken individually or in any possible technical combinations.

[0063] The vertical extension axis of the conductor body fixing end can pass through the upper terminal plate and / or the lower terminal plate.

[0064] In addition, the portion for fixing said at least one power supply conductor may be housed in the upper terminal plate and / or the lower terminal plate, and / or superimposed vertically, along the vertical axis, on the upper terminal plate and / or the lower terminal plate.

[0065] Furthermore, the conductor body of said at least one power supply conductor may pass, at least in part, particularly at the fastening end, through the plurality of electrochemical cells and the plurality of intermediate interconnectors. The fastening portion of said at least one power supply conductor electrical can be superimposed vertically, along the vertical axis, on the plurality of electrochemical cells and the plurality of intermediate interconnectors.

[0066] The fastening portion of said at least one power supply conductor may include a fastening head having a larger transverse dimension, relative to the vertical axis, in particular a diameter, greater than the largest transverse dimension, relative to the vertical axis, in particular a diameter, of the fastening end of the conductor body. The upper terminal plate and / or the lower terminal plate may include at least one opening, in particular a through opening, in which the fastening head of said at least one power supply conductor is housed, at least partially.

[0067] Thus, the conductor body, in particular the fastening end, may comprise an inner core and an outer sheath enclosing the inner core. The fastening head may comprise an upper portion of the head fixed to the outer sheath, in particular by welding, in particular by continuous, sealed welding.

[0068] In addition, the upper portion of the head can cover a portion of the upper inner core, in particular formed in the axial extension, with respect to the vertical axis, of the inner core, having a larger transverse dimension, with respect to the vertical axis, in particular a diameter, greater than the largest transverse dimension, with respect to the vertical axis, in particular a diameter, of the fixing end of the conductor body.

[0069] Said at least one orifice may include a counterbore on which the fixing head rests, in part.

[0070] Furthermore, the fastening portion of said at least one power supply conductor may include a fastening end having a larger transverse dimension, relative to the vertical axis, in particular a diameter, smaller than the largest transverse dimension, relative to the vertical axis, in particular a diameter, of the fastening end of the conductor body. The upper terminal plate and / or the lower terminal plate may include at least one opening, in particular a through opening, in which the fastening end of said at least one power supply conductor is housed, at least partially.

[0071] The conductor body, in particular the fastening end, may comprise an inner core and an outer sheath surrounding the inner core. The fastening end may comprise an upper portion of the end formed, in particular by machining, as an extension of the inner core, being made of the same material as the inner core, or attached to the outer sheath, in particular by welding, being made of a material different from that of the inner core, in particular the same material as the outer sheath or the upper terminal plate and / or the lower terminal plate.

[0072] The fastening tip may have a hollow end. Said at least one orifice may have, on its periphery, a hollow contour formed in the upper end plate and / or the lower end plate. The hollow end and the hollow contour may define walls between them intended to be fastened together, in particular by peripheral welding.

[0073] Furthermore, the fastening head or the fastening end of said at least one power supply conductor may have an external thread. Said at least one orifice may have an internal thread. The internal and external threads may together form a threaded connection for fastening said at least one power supply conductor to the upper terminal plate and / or the lower terminal plate.

[0074] The fixing head or the fixing end of said at least one power supply conductor can be fixed to the upper terminal plate and / or the lower terminal plate by welding, in particular by peripheral welding.

[0075] Furthermore, the mounting portion of said at least one power supply conductor may include a mounting hole, formed axially along the vertical axis, from the end of the mounting portion to the end of the mounting. The upper terminal plate and / or the lower terminal plate may include at least one hole, in particular a through hole, in which a mounting lug is housed, at least partially, fixed in particular by welding in said at least one through hole, having a projecting portion adapted to fit into the mounting hole.

[0076] The mounting hole may have an internal thread. The protruding portion of the mounting lug may have an external thread. The internal and external threads may together form a threaded connection for attaching said at least one power supply conductor to the upper terminal plate and / or the lower terminal plate.

[0077] Furthermore, the conductor body, in particular the fastening end, may comprise an inner core and an outer sheath enclosing the inner core. The fastening hole may be formed in the extension of the inner core at the fastening portion or in an added component on the fastening end, made in particular of the same material as the outer sheath. BRIEF DESCRIPTION OF THE FIGURES

[0078] Other advantages, purposes and special features of the invention will become apparent from the following non-limiting description of at least one embodiment of the present invention, with reference to the accompanying figures, in which: • Fig. 1 is a schematic view showing the operating principle of a high-temperature solid oxide electrolyzer (SOEC), Figure [Fig. 2] is a schematic exploded view of part of a high-temperature solid oxide electrolyzer (SOEC) including interconnectors according to the prior art, Figure 3 illustrates the principle of the architecture of a furnace on which a stack of high-temperature electrolysis cells (SOEC) or high-temperature fuel cells (SOFC) is placed. Figure 4 represents, in perspective and by observation from above, an example of a stack of SOEC / SOFC type solid oxide cells according to the prior art. Figure 5 illustrates, in perspective and by observation from above, an example of the prior art implantation of electric current rods on a stack of SOEC / SOFC type solid oxide cells. [Fig.6] represents, in isolation, an example of a current rod used in [Fig.5], Figure 7A schematically represents, in perspective, an example of an electrical connection device according to the invention comprising two power supply conductors and a stack of SOEC / SOFC type solid oxide cells operating at high temperature. Figure [7B] represents the device of Figure [7A] after the electrical power supply conductors have been attached. [Fig.7C] is a detailed cross-sectional view of [Fig.7B], [Fig.7D] schematically represents, in perspective and in isolation, an electrical supply conductor of [Fig.7A], Figure [7E] is a cross-sectional view of the power supply conductor of the [Fig.7D], Figure 8A schematically represents, in perspective, another example of an electrical connection device according to the invention comprising two power supply conductors and a stack of SOEC / SOFC type solid oxide cells operating at high temperature. Figure [8B] represents the device of Figure [8A] after the electrical power supply conductors have been attached. [Fig.8C] is a detailed cross-sectional view of [Fig.8B], [Fig.8D] schematically represents, in perspective and in isolation, an electrical supply conductor of [Fig.8A], Figure [8E] is a cross-sectional view of the power supply conductor of the [Fig.8D], Figure 9A schematically represents, in perspective, an example of an electrical connection device according to the invention comprising two power supply conductors and a stack of high-temperature SOEC / SOFC type solid oxide cells, Figure [9B] represents the device of Figure [9B] after the electrical power supply conductors have been attached. [Fig.9C] is a detailed cross-sectional view of [Fig.9B], [Fig.9D] schematically represents, in perspective and in isolation, an electrical supply conductor of [Fig.9A], Figure [9E] is a cross-sectional view of the power supply conductor of the [Fig.9D], Figure [1OA] schematically represents, in perspective, another example of a power supply conductor for an electrical connection device according to the invention. [Fig.1OB] is a cross-section of the power supply conductor of [Fig.1OA], Figure [1OC] shows a detailed cross-sectional view of a stack of SOEC / SOFC type solid oxide cells operating at high temperature for an electrical connection device according to the invention before fixing the power supply conductor of the [Fig.1OA], [Fig.1OD] is a view similar to that of [Fig.1OC] after fixing the power supply conductor of [Fig.1OA]. Figure 11A schematically represents, in perspective, another example of a power supply conductor for an electrical connection device according to the invention. [Fig.1 IB] is a cross-section of the power supply conductor of [Fig.11A], Figure [1IC] shows a detailed cross-sectional view of a stack of SOEC / SOFC type solid oxide cells operating at high temperature for an electrical connection device according to the invention before fixing the power supply conductor of the [Fig.llA], [Fig.llD] is a view similar to that of [Fig.llC] after fixing the power supply conductor of [Fig.llA]. Figure [12A] schematically represents, in perspective, another example of a power supply conductor for an electrical connection device according to the invention. [Fig.12B] is a cross-section of the power supply conductor of [Fig.1OA], Figure [12C] shows a detailed cross-sectional view of a stack high SOEC / SOFC type solid oxide cells temperature for an electrical connection device according to the invention before fixing the power supply conductor of the [Fig.12A], [Fig.12D] is a view similar to that of [Fig.12C] after fixing the power supply conductor of [Fig.12A]. Figure 13A schematically represents, in perspective, another example of a power supply conductor for an electrical connection device according to the invention. Figure [13B] is a cross-section of the power supply conductor of the [Fig.l3A] Figure [13C] shows a detailed cross-sectional view of a stack of SOEC / SOFC type solid oxide cells operating at high temperature for an electrical connection device according to the invention before fixing the power supply conductor of the [Fig. 13A], [Fig. 13D] is a view similar to that of [Fig. 1OC] after fixing the power supply conductor of [Fig. 13A]. Figure [14A] schematically represents, in perspective, another example of an electrical connection device according to the invention comprising two power supply conductors and a stack of SOEC / SOFC type solid oxide cells operating at high temperature, [Fig. 14B] is a detailed cross-sectional view of the electrical connection device of [Fig. 14A], Figure 15A schematically represents, in perspective, another example of a power supply conductor for an electrical connection device according to the invention. Figure [15B] is a cross-section of the power supply conductor of the [Fig.l5A] Figure [15C] shows a detailed cross-sectional view of a stack of SOEC / SOFC type solid oxide cells operating at high temperature for an electrical connection device according to the invention after fixing the power supply conductor of the [Fig. 15A], Figure [Fig. 10A] schematically represents, in perspective, another example of a power supply conductor for an electrical connection device according to the invention, [Fig.10B] is a cross-section of the power supply conductor of [Fig.10A], and Figure [10C] shows a detailed cross-sectional view of a stack high SOEC / SOFC type solid oxide cells temperature for an electrical connection device according to the invention after fixing the electrical supply conductor of the [Fig.lôA].

[0079] Throughout these figures, identical references may designate identical or analogous elements.

[0080] Furthermore, the different parts shown in the figures are not necessarily to a uniform scale, in order to make the figures more legible. DETAILED DESCRIPTION OF THE INVENTION

[0081] Figures 1 to 6 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 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 sake of clarity and precision, to illustrate the operation of the devices shown.

[0082] 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°C and 1000°C, and preferably between 650°C and 850°C.

[0083] Furthermore, the possible terms "upper" and "lower" are to be understood here in accordance with the normal orientation of a SOEC / SOFC type stack when in its configuration of use.

[0084] With reference to figures 7A to 16C, we will now describe several examples of the realization of electrical connection devices 100 between one or more, in particular two, power supply conductors 60 and a stack 20 of SOEC / SOFC type solid oxide cells operating at high temperature.

[0085] As described previously, such a stack 20 of SOEC / SOFC type solid oxide cells comprises: a plurality of electrochemical cells 41 each formed of a cathode, an anode and an electrolyte intercalated between the cathode and the anode; a plurality of intermediate interconnectors 42 each arranged between two adjacent electrochemical cells 41; an upper terminal plate 43 and a lower terminal plate 44 between which the plurality of electrochemical cells 41 and the plurality of intermediate interconnectors 42 are sandwiched.

[0086] As can be seen in [Fig.7A], and this also applies to the other embodiments described here, the upper terminal plate 43 and the lower terminal plate 44 extend respectively in a first horizontal plane PI and in a second horizontal plane P2, parallel to each other.

[0087] Furthermore, each power supply conductor 60 comprises a conductor body 61 and a fixing portion 64 for fixing the power supply conductor 60 to the upper terminal plate 43 and / or the lower terminal plate 44. In the embodiments described here, and in no way limiting the application, the fixing takes place on the upper terminal plate 43.

[0088] According to the invention, the conductor body 61 of a power supply conductor 60 has a mounting end 6If extending along a vertical axis X, perpendicular to the first P1 and second horizontal planes. Furthermore, the mounting portion 64 of the power supply conductor 60 is located at the end and in the axial extension, along the vertical axis X, of the mounting end 61f of the conductor body 61.

[0089] Advantageously, the vertical axis X of extension of the fixing end 6If of the conductor body 61 passes through the upper terminal plate 43 and / or the lower terminal plate 44.

[0090] In addition, the fixing portion 64 of an electrical supply conductor 60 can be housed in the upper terminal plate (43) and / or the lower terminal plate 44, as for example in the embodiments of Figures 7A-7E, 8A-8E, 9A-9E, 10A-10D, 11A-11D, 14A-14B, 15A-15C and 16A-16C, or can be superimposed vertically, along the vertical axis X, on the upper terminal plate 43 and / or the lower terminal plate 44, as for example in the embodiments of Figures 12A-12D and 13A-13D.

[0091] Furthermore, the conductor body 61 of a power supply conductor 60 can pass, at least in part, in particular at the fixing end 61f, through the plurality of electrochemical cells 41 and the plurality of intermediate interconnectors 42, as for example in all the embodiments described here except that of Figures 14A-14B in which the power supply conductors 60 pass through the upper terminal plate 43 outside of the electrochemical cells 41 and the intermediate interconnectors 42.

[0092] In the embodiment examples of figures 7A-7E, 8A-8E, 9A-9E and 14A-14B, the fastening portion 64 of each power supply conductor 60 has a fastening head 64t having, as seen in figures 7E, 8E and 9E, a diameter Dt greater than the diameter De of the fastening end 6If of the conductor body 61.

[0093] In addition, the upper terminal plate 43 has two through holes 71 in each of which is housed, at least partially, the fixing head 64t of one of the two electrical supply conductors 60.

[0094] Thus, each power supply conductor 60 passes through the structure of the stack 20 and is positioned perpendicularly against the terminal plate by means of a fixing head 64t which is positioned in the thickness of the terminal plate.

[0095] As seen in Figures 7E, 8E and 9E, the conductor body 61, in particular the fastening end 6If, comprises an inner core 61c, preferably of copper, and an outer sheath 61g, preferably of Inconel®, enveloping the inner core 61c, and the fastening head 64t comprises an upper portion of head 64ts fixed to the outer sheath 61g, in particular by welding S, in particular by continuous sealing welding.

[0096] The upper portion of the head 64ts can preferably be made of the same material as the terminal plate or even of the same material as the outer sheath 61g.

[0097] In the upper part of the mounting head 64t, a machining operation 67, in particular a counterbore, can be made to ensure clamping of the power supply conductor 60 in the case of threading as described below. However, clamping can also be achieved because the power supply conductor 60 is accessible under the lower terminal plate 44.

[0098] In the examples of Figures 7A-7E and 9A-9E, the upper head portion 64ts covers an upper inner core portion 64tc, formed in the axial extension, with respect to the vertical axis X, of the inner core 61c, which has a diameter Dtc greater than the diameter De of the fixing end 6If of the conductor body 61. Advantageously, this can optimize the distribution of electrical current at the connection. The upper inner core portion 64tc takes the form of a disk embedded in the upper head portion 64ts.

[0099] In the example of figures 8A-8E, the upper portion of the head 64ts is fitted onto the fixing end 6If, precisely fitted onto the inner core 61g and the outer sheath 61g.

[0100] In the examples of Figures 7A-7E and 8A-8E, the mounting head 64t of each power supply conductor 60 has an external thread, and each through-hole 71 has an internal thread. The internal and external threads together form a threaded connection for securing the power supply conductor 60 to the terminal plate. Thus, as shown schematically by arrow F in Figures 7A and 8A, each power supply conductor 60 is inserted vertically into a through-hole 71, and then clamping is performed, for example, by means of the machined part 67 or by accessing the power supply conductor 60 under the stack 20.

[0101] Additionally, the mounting head 64t of a power supply conductor 60 can be fixed by welding S, in particular by peripheral welding. Such a peripheral weld bead can improve the electrical connection. This welding S can be carried out in addition to the clamping achieved by the threaded connection, or a single weld S can be used, without the need for a threaded connection, as in the example of Figures 9A-9E.

[0102] Furthermore, as can be seen in figures 7A and 9A for example, a counterbore 72 can be provided for each through hole 71. The fixing head 64t can then bear, at least in part, against this counterbore 72.

[0103] Furthermore, as shown in the embodiments in Figures 10A-10D, 11A-11D, 15A-15C, and 16A-16C, the mounting portion of a power supply conductor 60 may include a mounting end 64e. The power supply conductors 60 are then inserted from below the stack 20. This mounting end 64e has a diameter De smaller than the diameter De of the mounting end 61f of the conductor body 61, as shown in Figures 10B and 11B. In addition, the upper terminal plate 43 has two openings 71 in which the two mounting ends 64e of the two power supply conductors 60 are housed, at least partially. Each opening 71 may or may not be through-hole.

[0104] As previously stated for the fixing head 64t, each fixing tip 64e may have an external thread and each orifice 71 may have an internal thread, together forming a threaded connection for fixing the power supply conductors 60 to the upper terminal plate 43. Each orifice 71 thus forms a tapped hole for receiving a threaded tip.

[0105] Additionally or alternatively, each fixing tip 64e can be fixed to the terminal plate by welding S, in particular by peripheral welding.

[0106] The fixing tip 64e can be machined onto the inner core 61c or welded to the outer sheath 61g. In the case of machining, a sealed peripheral weld between the end of the outer sheath 61g and the end plate is advantageously made to prevent the material of the inner core 61c, particularly copper, from being exposed to atmospheric oxygen. Indeed, at high temperatures, operating temperatures can exceed 300°C, and encapsulating the inner core 61c, particularly in the form of a copper bar, within a sheath, especially one made of a superalloy, can provide resistance to these high temperatures.

[0107] In the example of figures 10A-10D, the fixing tip 64e has an upper portion of tip 64es made, in particular by machining, in the extension of the inner core 61c, being made of the same material as the inner core 61c. The orifice 71 is not through here, it is a blind hole.

[0108] In the example of Figures 11A-11D, the fastening tip 64e has an upper portion of the tip 64es attached to the outer sheath 61g, in particular by welding, being made of a material different from that of the inner core 61c, in particular the same material as the outer sheath 61g or the end plate. The orifice 71 is through-hole here.

[0109] It should be noted that all connection solutions based on a threaded mechanical link can also be replaced or supplemented by connections of Welded connections are particularly suitable if the electrical connection makes this type of assembly difficult. For welded connections, it can be advantageous to machine the ferrules and end plates to allow for a butt weld between the two parts, between two thin walls, thus minimizing heat gain during the welding process. The ferrule can be made of the same material as the outer 61g sheath or the same material as the end plate.

[0110] In the examples of Figures 15A-15C and 16A-16C, the fastening tip 64e has a hollow end 64ec and the orifice 71 has, on its periphery, a hollow contour 71c formed in the end plate. The hollow end 54ec and the hollow contour 71c define walls between them intended to be joined together by peripheral welding S. In the example of Figures 15A-15C, the fastening tip 64e is made of the same material as the outer sheath 61g, whereas in the example of Figures 16A-16C, the tip 64e is made of a different material, in particular that of the end plate.

[0111] Furthermore, by equipping the terminal plate with a fixing lug 81, as in the examples of figures 12A-12D and 13A-13D, positioned vertically, the connection can also be made by electrical supply conductors 60 with a fixing portion 64 comprising a fixing orifice 64o, formed axially along the vertical axis X, from the end of the fixing portion 64 to the fixing end 6If.

[0112] The fixing lug 81 can be threaded and welded into the end plate. The fixing lug 81 advantageously comprises a projecting portion 81s adapted to fit into the fixing hole 64o, which advantageously comprises an internal thread forming a threaded connection with the external thread of the projecting portion 81s.

[0113] As in the example of Figures 12A-12D, the mounting hole 64o can be formed in the extension of the inner web 61c at the mounting portion 64. A tapped hole is thus directly formed in the inner web 61c. In this case, a watertight weld as described above is advantageously achieved.

[0114] Alternatively, as in the example of Figures 13A-13D, the fixing hole 64o can be formed in an added piece 65 on the fixing end 6If, made in particular of the same material as the outer sheath 61g.

[0115] Furthermore, in the example of Figures 14A-14B, the power supply conductors 60 pass through the outside of the stack 20. Advantageously, this can accommodate a stack 20 design for which it would not be possible to run the power supply conductors 60 through the inside of the stack 20 itself. Therefore, the terminal plate can have a design adapted to allow connection on the outer edges. Here, the upper terminal plate 43 has projecting portions 43s on which the holes 71 are formed.

[0116] It should be noted that advantageously, the largest transverse dimension, in particular the diameter, of the orifices 71 may be slightly greater than the largest transverse dimension, in particular the diameter, of the outer sheath 61g in order to ensure the absence of contact between the power supply conductor 60 and the intermediate interconnectors 42.

[0117] To determine which embodiment is most suitable depending on the device 100 considered, it is possible to perform finite element calculations to estimate the current and power densities associated with the ohmic losses in the plates 43, 44. The compromise of choosing one solution over another must then be made with regard to electrical performance (minimization of losses and homogeneity of current distribution) and the complexity of manufacturing and integrating the solution.

[0118] Such calculations have been performed and show that the solution in Figures 7A-7E appears to be the most efficient in minimizing Joule effect losses and exhibiting good homogeneity. However, its geometry can be complex to implement. The solution in Figures 11A-11D is simple to produce, but significant stresses arise at the interface with a high current density. To reduce this, interfaces between the inner core and the end plate with a large contact area should be favored.

[0119] Table 1 below summarizes the results obtained according to the solutions studied: Embodiment Resistance of the connecting part (p Q) Maximum Joule effect (W.m3) Maximum current density (A.m2) Figures 5-6 (previous art) 260 5.79 x 106 4.15 x 106 Figures 7A-7E 16 5.52 x 105 2.73 x 106 Figures 9A-9E 22 2.77 x 106 4.81 x 106 Figures 11A-11D 40 7.51 x 106 3.9 x 106 Table 1

[0120] All the envisaged embodiment examples make it possible to significantly reduce the resistance of the connection compared to the standard current rod.

[0121] Of course, the invention is not limited to the embodiments just described. Various modifications can be made to them by a person skilled in the art.

Claims

Demands

1. An electrical connection device (100) between a power supply conductor (60) and a stack (20) of high-temperature SOEC / SOFC type solid oxide cells, comprising: - a stack (20) of high-temperature SOEC / SOFC type solid oxide cells, comprising: - a plurality of electrochemical cells (41), each formed of a cathode, an anode, and an electrolyte intercalated between the cathode and the anode, - a plurality of intermediate interconnectors (42), each arranged between two adjacent electrochemical cells (41), - an upper terminal plate (43) and a lower terminal plate (44) between which the plurality of electrochemical cells (41) and the plurality of intermediate interconnectors (42) are sandwiched,the upper terminal plate (43) and the lower terminal plate (44) extending substantially respectively in a first horizontal plane (PI) and in a second horizontal plane (P2), parallel to each other, - at least one power supply conductor (60), comprising: - a conductor body (61), - a fixing portion (64), for fixing said at least one power supply conductor (60) to the upper terminal plate (43) and / or the lower terminal plate (44), characterized in that the conductor body (61) of said at least one power supply conductor (60) has a fixing end (61f) extending along a vertical axis (X), perpendicular to the first (PI) and second (P2) horizontal planes, and in that the fixing portion (64) of said at least one power supply conductor (60) is located at the end and in the axial extension, along the vertical axis (X),of the mounting end (61f) of the conductor body (61).

2. Device according to claim 1, wherein the vertical axis (X) of extension of the fixing end (61f) of the conductor body (61) passes through the upper terminal plate (43) and / or the lower terminal plate (44).

3. Device according to claim 1 or 2, wherein the fixing portion (64) of said at least one power supply conductor (60) is housed in the upper terminal plate (43) and / or the lower terminal plate (44), and / or superimposed vertically, along the vertical axis (X), on the upper terminal plate (43) and / or the lower terminal plate (44).

4. Device according to any one of the preceding claims, wherein the conductor body (61) of said at least one power supply conductor (60) passes, at least in part, in particular at the fixing end (61f), through the plurality of electrochemical cells (41) and the plurality of intermediate interconnectors (42), the fixing portion (64) of said at least one power supply conductor (60) being superimposed vertically, along the vertical axis (X), on the plurality of electrochemical cells (41) and the plurality of intermediate interconnectors (42).

5. Device according to any one of the preceding claims, wherein the fastening portion (64) of said at least one power supply conductor (60) comprises a fastening head (64t) having a larger transverse dimension (Dt), with respect to the vertical axis (X), in particular a diameter, greater than the largest transverse dimension (De), with respect to the vertical axis (X), in particular a diameter, of the fastening end (61f) of the conductor body (61), and wherein the upper terminal plate (43) and / or the lower terminal plate (44) comprises at least one orifice (71) in which the fastening head (64t) of said at least one power supply conductor (60) is housed, at least partially.

6. Device according to claim 5, wherein the conductor body (61), in particular the fastening end (61f), comprises an inner core (61c) and an outer sheath (61g) enclosing the inner core (61c), and wherein the fastening head (64t) comprises an upper head portion (64ts) fixed to the outer sheath (61g), in particular by welding (S), in particular by continuous sealed welding.

7. Device according to claim 6, wherein the upper head portion (64ts) covers an upper inner core portion (64tc), in particular formed in the axial extension, with respect to the vertical axis (X), of the inner core (61c), having a greater transverse dimension (Dtc), with respect to the vertical axis (X), in particular a diameter, greater than the largest transverse dimension (De), with respect to the vertical axis (X), in particular a diameter, of the fixing end (61f) of the conductor body (61).

8. Device according to any one of claims 5 to 7, wherein said at least one orifice (71) has a counterbore (72) on which rests, in part, the fixing head (64t).

9. Device according to any one of claims 1 to 4, wherein the fastening portion (64) of said at least one power supply conductor (60) comprises a fastening tip (64e) having a larger transverse dimension (De), with respect to the vertical axis (X), in particular a diameter, smaller than the largest transverse dimension (De), with respect to the vertical axis (X), in particular a diameter, of the fastening end (61f) of the conductor body (61), and wherein the upper terminal plate (43) and / or the lower terminal plate (44) comprises at least one orifice (71) in which the fastening tip (64e) of said at least one power supply conductor (60) is housed, at least partially.

10. Device according to claim 9, wherein the conductor body (61), in particular the fixing end (61f), comprises an inner core (61c) and an outer sheath (61g) enveloping the inner core (61c), and wherein the fixing tip (64e) comprises an upper tip portion (64es) formed, in particular by machining, in the extension of the inner core (61c), being made of the same material as the inner core (61c), or attached to the outer sheath (61g), in particular by welding, being made of a material different from that of the inner core (61c), in particular of the same material as the outer sheath (61g) or as the upper terminal plate (43) and / or the lower terminal plate (44).

11. Device according to claim 9 or 10, wherein the fixing tip (64e) has a hollow end (64ec) and wherein said at least one orifice (71) has, at its periphery, a hollow contour (71c) formed in the upper end plate (43) and / or the lower end plate (44), the hollow end (54ec) and the hollow contour (71c) defining between them walls intended to be fixed together, in particular by peripheral welding.

12. Device according to any one of claims 5 to 11, wherein the fixing head (64t) or the fixing tip (64e) of said at least one power supply conductor (60) has an external thread and wherein said at least one orifice (71) has an internal thread, together forming a threaded connection for fixing said at least one power supply conductor (60) to the upper terminal plate (43) and / or the lower terminal plate (44).

13. Arrangement according to any one of claims 5 to 12, wherein the fixing head (64t) or the fixing tip (64e) of said at least one power supply conductor (60) is fixed to the upper terminal plate (43) and / or the lower terminal plate (44) by welding (S), in particular by peripheral welding.

14. Device according to any one of claims 1 to 4, wherein the fixing portion (64) of said at least one power supply conductor (60) has a fixing hole (64o), formed axially, along the vertical axis (X), from the end of the fixing portion (64) to the fixing end (61f), and wherein the upper terminal plate (43) and / or the lower terminal plate (44) has at least one hole (71) in which is housed, at least partially, a fixing lug (81), fixed in particular by welding (S) in said at least one hole (71), having a projecting portion (81s) adapted to come into the fixing hole (64o).

15. Device according to claim 14, wherein the fixing hole (64o) has an internal thread and wherein the projecting portion (81s) of the fixing lug (81) has an external thread, together forming a threaded connection for fixing said at least one power supply conductor (60) to the upper terminal plate (43) and / or the lower terminal plate (44).

16. Device according to claim 14 or 15, wherein the conductor body (61), in particular the fixing end (61f), comprises an inner core (61c) and an outer sheath (61g) enveloping the inner core (61c), the fixing orifice (64o) being formed in the extension of the inner core (61c) at the fixing portion (64) or in an added piece (65) on the fixing end (61f), made in particular of the same material as the outer sheath (61g).