Method for manufacturing a solid oxide electrochemical reactor comprising sealing and insulation assemblies

Abstract

A method for manufacturing a solid oxide electrochemical reactor, comprising the following steps: – producing an electrically insulating support (1) with through-holes (2); – depositing at least one fusible seal bead (15) onto a selected element from the group consisting of the interconnecting plates (6) and the electrically insulating support (1); – performing a hardening operation on the fusible seal bead (15); – compressing the fusible seal bead (15) along the stacking direction and plastically deforming it; – pressing an alternating stack and heating it to the melting temperature of the fusible seal bead (15), so that the fusible seal bead (15) extends into the through-holes (2) of the electrically insulating support (1) and forms a seal connecting two interconnecting plates (6) through these through-holes (2). Figure for the abstract: Fig. 9

Description

Title of the invention: Method for manufacturing a solid oxide electrochemical reactor comprising sealing and insulation assemblies Technical field

[0001] The invention relates to the technical field of solid oxide electrochemical reactors, and more precisely solid oxide electrolyzers (SOEC, "Solid Oxide Electrolyzer Cell") and solid oxide fuel cells (SOFC, "Solid Oxide Fuel Cell").

[0002] These electrolysers and fuel cells are electrochemical reactors of the same nature but with reverse operation, operating at high temperature, currently of the order of 600°C to 1000°C. They make it possible, in the case of an electrolyser, to obtain dihydrogen and dioxygen from water (for the electrolysis of water), and in the case of a fuel cell, to provide electrical energy from dihydrogen, or another fuel, and dioxygen.

[0003] These electrochemical reactors consist of one or more stacks of electrochemical cells held tightly together to ensure electrical contacts and sealing. Each electrochemical cell comprises a layer of solid electrolyte sandwiched between two layers of electrodes. The layer of solid electrolyte allows the transport of ions between the anodic and cathodic layers, the latter being the site of the chemical reactions.

[0004] In a "SOEC" type reactor, the water molecule is dissociated into dihydrogen at the hydrogen electrode (cathode), the O2 ions migrate through the electrolyte to recombine on the oxygen electrode side (anode) into dioxygen. "SOEC" cells thus produce dihydrogen by dissociating water molecules.

[0005] In a "SOFC" type reactor, oxygen is reduced at the oxygen electrode (cathode), the O2 ions migrate through the electrolyte. An oxidation reaction then takes place at the hydrogen electrode (anode) and the "SOFC" cells thus produce electricity and water by combining dihydrogen and dioxygen.

[0006] These electrochemical reactors are arranged in alternating stacks of electrochemical cells and interconnection plates. The interconnection plates are interposed between the cells to ensure sealing between cells, as well as to manage the supply and collection of gases or liquids participating in the reaction. Sealing between interconnection plates is therefore a critical point to avoid mixing of fluids.

[0007] The interconnection plates are also conductive and allow the connection electrical insulation of the cells. The electrical insulation between interconnection plates is therefore also a critical point, to avoid short-circuiting a cell.

[0008] The sealing and electrical insulation within these electrochemical reactors are therefore among the most critical points in operation, for reasons of performance and quality, operational safety, lifespan and security. PRIOR ART

[0009] Document FR3014246 describes an electrochemical reactor comprising means high-performance sealing.

[0010] This electrochemical reactor comprises: - an alternating stack of electrochemical cells and interconnection plates, in a stacking direction, the electrochemical cells each comprising a layer of solid electrolyte arranged between two layers of electrodes, and the interconnection plates comprising electrically conductive plates provided with reaction fluid distribution channels; - at least one transverse channel for circulation of reaction fluids between the interconnection plates; - sealing and insulation assemblies arranged between the interconnection plates.

[0011] These sealing means give good functional results. However, they are difficult and expensive to manufacture and implement, and suffer from significant manufacturing hazards, particularly for stacks comprising a large number of cells. In particular, this solution is not very suitable in the context of industrial production, which is nevertheless necessary for the deployment of solid oxide electrochemical reactor solutions. Statement of the invention

[0012] The aim of the invention is to improve the solid oxide electrochemical reactors of the prior art.

[0013] To this end, the invention relates to a method for manufacturing a solid oxide electrochemical reactor which comprises: - an alternating stack of electrochemical cells and interconnection plates, in a stacking direction, the electrochemical cells each comprising a layer of solid electrolyte arranged between two layers of electrodes, and the interconnection plates comprising electrically conductive plates provided with reaction fluid distribution channels; - at least one transverse channel for circulation of reaction fluids between the interconnection plates; - sealing and insulation assemblies arranged between the plates interconnection.

[0014] This method comprises the following steps: - production of an electrically insulating support comprising a sheet of electrically insulating material pierced with through openings; - depositing at least one electrically insulating fusible joint bead on an element selected from the group consisting of interconnection plates and the electrically insulating support; - carry out a hardening operation of the fusible joint cord; - compress the fusible joint cord along the stacking direction, and deform it plastically; - produce an alternating stack of electrochemical cells and interconnection plates, and place the electrically insulating support between two interconnection plates; - pressing said alternating stack along the stacking direction, and bringing it to a melting temperature of the fusible joint bead, so that the fusible joint bead extends into the through openings of the electrically insulating support, and forms a seal connecting two interconnecting plates through these through openings.

[0015] The reaction fluids referred to are the fluids that are brought to the electrodes and the fluids that are drained from the electrodes. These are, depending on the operating mode (fuel cell or electrolyzer) of the electrochemical reactor, high-temperature water vapor, dihydrogen, dioxygen, etc.

[0016] The method according to the invention makes it possible to produce electrochemical reactors benefiting from the highest performance in terms of electrical insulation and sealing, jointly.

[0017] In the sealing and insulation assemblies thus produced, the electrically insulating support and the fusible joint cooperate to form a seal which adheres to the interconnection plates, so as to ensure electrical insulation and to form a gas-tight barrier at the interfaces between this sealing and insulation assembly and the interconnection plates.

[0018] In addition to the performance provided by the use of sealing and insulation assemblies, the invention allows better control of manufacturing, and therefore leads to better quality electrochemical reactors.

[0019] In the prior art, the implementation of sealing and insulation assemblies is essentially the responsibility of the laboratory or small series production, with meticulous and difficult to repeat handling. The invention allows industrial-scale production of solid oxide electrochemical reactors, with the required quality and repeatability. The invention thus contributes to the deployment of these solutions which are required for the future, in a context of diversification of energy sources.

[0020] The invention makes it possible to increase production scales, also by increasing the capacities of solid oxide electrochemical reactors, by concretely allowing the increase in the size of the stacks. The invention is thus particularly suitable for the current objectives of increasing the number of layers in the reactors, leading to an increase in the height of the stacks, and increased complexity in the control of their manufacture. The management of height variations is in fact particularly critical during the manufacture of the reactors.

[0021] The expected performance for future solid oxide electrochemical reactors tends to require the implementation of very high stacks which may include hundreds of interconnection plates. In addition, the cumulative length of the sealing barriers (i.e. the addition of the sealing joint lengths) for each stage of an electrochemical reactor may be of the order of 2 meters. In the case, for example, of a 20 kW power reactor consisting of 75 stages, a cumulative length of the sealing joints of approximately 150 m is achieved.

[0022] The invention allows a lowering of the total height of the stacks before pressing, in combination with the creation of shaped and height-calibrated bearing surfaces on the fusible joint beads. The lowering of the stack height before pressing also results in a reduction of the lowering stroke of the stack during clamping, thus reducing the complexity of the necessary guides, and reducing the risk of the stack collapsing.

[0023] The invention thus improves the quality of the sealing and electrical insulation barriers, and simplifies the assembly of the stacks.

[0024] The method according to the invention may include the following additional characteristics, alone or in combination:

[0025] - in the step of producing the electrically insulating support, the through openings are arranged in discontinuous grooves arranged along joint lines;

[0026] - in the step of producing the electrically insulating support, said sheet of material electrically insulating is further pierced with a central window for the positioning of an electrochemical cell, the joining lines being arranged around this central window;

[0027] - in the step of producing the electrically insulating support, said sheet of material electrically insulating is further pierced with at least one side window intended for the passage of the transverse channel for circulation of the reaction fluids, the joining lines being arranged around this side window;

[0028] - in the step of producing the electrically insulating support, several joining lines parallels are arranged side by side;

[0029] - said parallel joining lines are formed of discontinuous grooves which have discontinuities arranged in staggered rows;

[0030] - the electrically insulating support comprises a single-piece frame;

[0031] - in the step of depositing at least one fusible joint bead, joint beads fuses are placed on the edge of each through opening;

[0032] - in the step of compressing the fusible joint bead, all the joint beads fuse are calibrated at the same height;

[0033] - in the step of compressing the fusible joint bead, the compression is carried out by a press comprising jaws extending along a flat surface substantially perpendicular to the stacking direction;

[0034] - in the step of compressing the fusible joint bead, the compression is carried out by applying a predetermined force;

[0035] - in the step of compressing the fusible joint bead, the compression is carried out by applying a predetermined displacement;

[0036] - in the step of compressing the fusible joint bead, the fusible joint bead is plastically deformed to present flat surfaces substantially perpendicular to the stacking direction;

[0037] - in the step of producing an alternating stack of electrochemical cells and interconnection plates, the stacking is carried out in a press comprising guiding means following the stacking direction, the step of compressing the fusible joint bead being carried out in this same press;

[0038] - the fusible joint cord comprises: a glass or glass-ceramic powder, or ceramic; a solvent; and a binder;

[0039] - in the step of depositing at least one fusible joint bead, the joint bead fuse is deposited on an interconnection plate; and in the step of compressing the fusible joint cord, the compression is carried out on the assembly formed by this interconnection plate and the fusible joint cord; and in the step of producing an alternating stack of electrochemical cells and interconnection plates, the fusible joint cord is brought into contact with the electrically insulating support;

[0040] - in the step of depositing at least one fusible joint bead, the joint bead fuse is deposited on the electrically insulating support; and in the step of compressing the fusible joint cord, the compression is carried out on the assembly formed by this electrically insulating support and the fusible joint cord; and in the step of producing an alternating stack of electrochemical cells and interconnection plates, the fusible joint cord is brought into contact with an interconnection plate;

[0041] - in the step of depositing at least one fusible joint bead, the joint bead fuse is deposited on the areas between the joint lines. PRESENTATION OF FIGURES

[0042] Other characteristics and advantages of the invention will emerge from the non-limiting description which follows, with reference to the appended drawings in which:

[0043] - [Fig. 1] is a perspective view of an electrically insulating support implemented in the method according to the invention;

[0044] - [Fig.2] is a partial sectional view of an alternating stack of electric cells trochemicals and interconnection plates, implemented in the method according to the invention;

[0045] - [Fig.3] is a detailed view of a sealing and insulation assembly put in works in the method according to the invention;

[0046] - [Fig.4], [Fig.5], [Fig.6], [Fig.7], [Fig.8], [Fig.9], [Fig.10], and [Fig.l 1] illustrate steps of the method according to a first embodiment of the invention;

[0047] - [Fig.12], [Fig.13], [Fig.14], [Fig.15], [Fig.16], [Fig.17], [Fig.18] and [Fig. 19] illustrate the steps of the method according to a second embodiment of the invention.

[0048] Elements similar and common to the various embodiments bear the same reference numbers in the figures. DETAILED DESCRIPTION

[0049] The subject of the invention is a method for manufacturing a solid oxide electrochemical reactor, such as a solid oxide fuel cell, or a solid oxide electrolyser, with an operating temperature of the order of 600 to 1000°C. This electrochemical reactor can also be reversible, being able to operate alternately in the two modes (solid oxide electrolyser or solid oxide fuel cell).

[0050] The solid oxide electrochemical reactor comprises: - an alternating stack of electrochemical cells and interconnection plates, in a stacking direction, the electrochemical cells each comprising a layer of solid electrolyte arranged between two layers of electrodes, and the interconnection plates comprising electrically conductive plates provided with reaction fluid distribution channels; - at least one transverse channel for circulation of reaction fluids between the interconnection plates; - sealing and insulation assemblies arranged between the interconnection plates.

[0051] Solid oxide electrochemical reactors are of known construction and will not be described in more detail here, apart from the elements relating to the invention which concerns the manufacturing process of such an electrochemical reactor.

[0052] The electrochemical reactor illustrated has, for example, a constitution similar to that described in document FR3014246, and notably comprises sealing and insulation assemblies, arranged between the interconnection plates.

[0053] [Fig.l] illustrates an electrically insulating support 1 provided to form one of the sealing and insulating assemblies of the electrochemical reactor according to the invention.

[0054] This electrically insulating support 1 comprises a sheet of insulating material pierced with a through opening 2. This sheet of insulating material is preferably made of a material with high insulating properties, for example a mica sheet. Any mineral compound other than mica can also be used, as well as ceramics, polymers, or any other material suitable for the operating temperature and having the required electrically insulating properties.

[0055] In the present example, the electrically insulating support 1 comprises a single-piece frame which has the general shape of a square frame, intended to be placed in a stack of electrochemical cells and interconnection plates which are themselves square. The electrically insulating support 1 of this particular example forms a frame with a central window 3 provided for the positioning of an electrochemical cell. This assembly will be sandwiched between two interconnection plates to form the elementary pattern of the stack.

[0056] The electrically insulating support 1 may also, as a variant, have any other shape to correspond to stacks of different shapes (rectangular, circular, oval, etc.) and may also have shapes other than a frame, such as a linear shape, and may perform its function on only a portion of an area between two interconnection plates.

[0057] The electrically insulating support 1 further comprises, in this example, lateral windows 4 which participate in the constitution of transverse channels for the circulation of reaction fluids between the interconnection plates.

[0058] The through openings 2 of the insulating support 1 are, in this example, produced in the form of discontinuous grooves extending along the joining lines. These joining lines are arranged around the central window 3 and around the side windows 4, according to the example illustrated in [Fig.l].

[0059] Several joining lines can be arranged in parallel and side by side, this is the case of the joining lines between each side window 4 and the edge of the electrically insulating support 1. In this case, the discontinuities of the grooves are preferably placed in staggered rows, in order to lengthen the possible leakage path between two adjacent joining lines, to improve the sealing of the finished stack. The material of the electrically insulating support 1 can therefore have a certain porosity, which will not harm the sealing once joints are put in place in the discontinuous grooves. constituting the through openings 2.

[0060] [Fig.2] is a partial sectional view illustrating an elementary pattern of the stack of the electrochemical reactor, with an electrochemical cell 5 arranged between two interconnection plates 6. An alternating stack within the meaning of the present invention thus comprises, in a known manner, an alternation of electrochemical cells 5 and interconnection plates 6, as many times as necessary depending on the size of the desired stack, superimposed in a stacking direction D.

[0061] Each electrochemical cell 5 comprises a solid electrolyte layer 8 arranged between two electrode layers 9, 10, one of which is an anode and the other is a cathode. Each interconnection plate 6 comprises different layers 6A, 6B, 6C allowing the distribution of the reaction fluids. The electrochemical cells 5 and the interconnection plates 6 may for example be in accordance with the description of document WO2016026740.

[0062] The partial section of [Fig.2] illustrates a portion of the edge of this elementary pattern of the alternating stack of the electrochemical reactor, and illustrates in particular a transverse channel 7 for circulation of the reaction fluids between the interconnection plates 6. In a known manner, each transverse channel 7 allows a reaction fluid (whether supplied or produced at the level of the electrode layers 9, 10) to circulate from one interconnection plate 6 to the other.

[0063] The interconnection plates 6 of this example comprise three layers 6A, 6B, 6C. In the view of [Fig.2], where only one electrochemical cell 5 is illustrated: - a first external layer 6A is provided with reaction fluid distribution channels for the electrochemical cell which is located above the interconnection plate 6 in question; - a second external layer 6B is provided with reaction fluid distribution channels for the electrochemical cell which is located below the interconnection plate 6 in question; - a central layer 6C is provided with channels intended for the circulation of a cooling fluid.

[0064] The reaction fluid distribution channels allow either the supply of fluids necessary for the reaction to the electrodes, or the drainage from the electrodes of the fluids produced by the reaction (water vapor, oxygen, hydrogen, etc.).

[0065] In the example illustrated in [Fig.2], layer 6A of the lower interconnection plate 6 manages the reaction fluids for the lower electrode 10, while layer 6B of the upper interconnection plate 6 manages the reaction fluids for the upper electrode 9.

[0066] Sealing means allow the reaction fluids to be directed to or from the appropriate electrodes 9, 10, avoiding mixing of the fluids. In this example, a seal 11 is arranged between the solid electrolyte layer 8 and the interconnection plate 6 below, to divide the flows specific to each electrode.

[0067] The electrochemical reactor further comprises a sealing and insulation assembly 12 making it possible to create a seal between the interconnection plates 6.

[0068] This sealing and insulation assembly 12 is formed of the electrically insulating support 1 of [Fig.l], associated with a sealing gasket 13 which extends into the through openings 2 of the electrically insulating support 1 by connecting two interconnection plates 6 through the through openings 2.

[0069] [Fig. 3] is a detailed perspective view of the sealing and insulation assembly 12 with the electrically insulating support 1, one of its through openings 2, and the sealing gasket 13 which has two faces 14 each intended to adhere to an interconnection plate 6. This figure thus presents the sealing barrier formed by the method according to the invention.

[0070] A high-performance seal is thus achieved from one interconnection plate 6 to the other, by a sealing gasket 13 passing through each through opening 2.

[0071] The arrangement of the through openings 2, here produced in the form of jointing lines along which discontinuous grooves extend, ensures that the physical integrity of the electrically insulating support 1 is maintained, which remains in one piece, thus ensuring proper positioning of all the joints. The jointing lines may be straight lines, curved lines, dotted lines, wavy lines, or any other shape suitable for a particular application.

[0072] The method according to the invention comprises a first step of producing the electrically insulating support 1 of [Fig.l], pierced with the through openings 2. This step consists of cutting to size a sheet of electrically insulating material, mica in this example, and forming in this sheet the various windows 3, 4 required, as well as the through openings 2. Any suitable manufacturing method can be used here, for example: machining the mica sheet, laser cutting, punching, machining by milling, etc., or even molding or additive manufacturing for materials suitable for this.

[0073] The next step of the method consists of depositing at least one fusible joint bead 15 on the electrically insulating support 1. The volume of fusible joint beads 15 deposited is determined with the aim of filling all the through openings 2, and of adhering to the interconnection plates 6 on either side of each through opening 2.

[0074] [Fig.4] illustrates in perspective the result of this deposit of fusible joint bead and [Fig.5] is the corresponding front view.

[0075] In the present example, fusible joint cords 15 are deposited on each face of the electrically insulating support 1, for better distribution of the joint.

[0076] In this example, the fusible joint beads 15 are deposited on the areas between the joining lines, that is to say on the solid parts of the electrically insulating support 1 which are located between the joining lines of the through openings 2. The fusible joint beads 15 are therefore deposited at the edge of each through opening 2. Each through opening 2 is thus bordered by fusible joint beads 15.

[0077] The fusible joint beads 15 are for example deposited in the form of paste by an extrusion device, such as a robotic arm equipped with a syringe. Any other method suitable for depositing paste beads can be used, for example spraying, additive manufacturing, strip joint deposition, etc.

[0078] In the present example, these fusible joint cords 15 have a width of the order of 1 to 2 mm.

[0079] The material constituting the deposited fusible joint cords 15 is a material having a melting point beyond which it will form a seal impervious to reaction fluids and electrically insulating. Preferably, this material is based on glass or glass-ceramic. It can also be based on other materials, such as a ceramic or a suitable polymer.

[0080] In the present example, the fusible joint bead is made of a mixture of glass powder, an ethanol-type solvent, and a terpineol-type binder. This joint bead 15 is fusible, because when the melting point of the glass powder is reached, the glass powder agglutinates into molten glass, to form the joint extending into the through openings 2 of the electrically insulating support 1. The glass powder in this example is ground glass, with an average particle size between 30 μm and 0.1 μm.

[0081] The next step of the method, after the deposition of the fusible joint beads 15, consists of carrying out an operation of hardening the fusible joint beads 15.

[0082] In the present example, taking into account the material chosen for the fusible joint bead 15, this hardening step can be carried out by implementing the evaporation of the solvent (here ethanol), by a drying operation. This drying operation can be carried out by any suitable means, possibly providing ventilation operations, temperature increase, etc.

[0083] The drying time which corresponds to the evaporation of the most volatile solvents is a function of the quantity of fusible joint deposited and the geometry of the deposited bead. In practice, the external surface of the fusible joint beads can form a rigid crust in a few minutes, and the core drying of the bead can take several hours. A drying time of 24 hours at room temperature can, for example, be implemented.

[0084] Alternatively, this curing step may be carried out by any other means suitable for the material of the fusible joint bead. For example, exposure to UV rays in the case of a fusible joint comprising a UV-crosslinkable element, or by implementing a resting time in the case of a fusible joint comprising a curable two-component mixture.

[0085] Thanks to this step, the fusible joint cords 15 undergo an increase in their hardness, and keep the same shape as in FIGS. 4 and 5. The assembly formed by the electrically insulating support 1 and the hardened fusible joint cords 15 is then manipulable.

[0086] The next step of the method, illustrated in the front view of [Fig.6], consists of placing this assembly under pressure, and compressing the fusible joint beads 15 in the stacking direction D.

[0087] [Fig. 6] schematically illustrates a press comprising jaws 16 which extend along a flat surface the size of the electrically insulating support 1 and substantially perpendicular to the stacking direction, and which are adapted to compress all the fusible joint beads 15. Preferably, the jaws 16 are as perfectly perpendicular as possible to the stacking direction.

[0088] The result of the operation of compressing the fusible joint beads 15 is illustrated in the front view of [Fig.7] and in the perspective view of [Fig.8]. The fusible joint beads 15 have been plastically deformed, that is to say they retain the acquired shape, even after removal from the press.

[0089] The fusible joint cords 15 thus deformed have a height H (corresponding to their dimension along the compression direction D) which is calibrated by the compression step.

[0090] Preferably, the compression can be calibrated by predetermining the pressure applied by the press. The step of compressing the fusible joint beads 15 is then carried out by compression consisting of applying a predetermined force. In the present example, taking into account the dimensions of the elements of the stack, this clamping force may be between 1 kN and 1,000 kN, and preferably between 20 and 100 kN. “Compression force-crushing” charts may be implemented for the different geometries of interest.

[0091] All the fusible joint cords 15 are thus calibrated to the same height H by cold pressing.

[0092] According to a particularly advantageous example, the compression stroke applied to each fusible joint bead 15 is equal to the tolerance linked to the operation of depositing the fusible joint beads 15, with a multiplying factor. For example, this compression stroke may be equal to three times (multiplying factor of 3) 50 μm, or 150 μm, in the case where the tolerance linked to the operation of depositing the joint beads fuse 15 is 50 pm. This ensures that all fuse joint 15 cords will be effectively compressed and calibrated in height.

[0093] The tolerance linked to the operation of depositing the fusible joint beads 15 depends on the process and the equipment used to carry out the deposit, and corresponds to the possible interval of the differences in joint height actually deposited for the same instruction.

[0094] Alternatively, the compression step may be carried out according to other criteria. For example, the compression step of the fusible joint beads 15 is carried out by a compression consisting of applying a predetermined displacement, that is to say by calibrating the displacement of the jaws 16 by a predetermined value, calibrating the predetermined height H for each fusible joint bead 15.

[0095] The compression step also makes it possible to do without any operation of shaping or rectification of the fusible joint beads 15, which could have been necessary in the prior art, such as cutting or flattening the pins left by the paste deposition operation, etc.

[0096] According to a particularly advantageous example, the compression step also makes it possible to form a flat surface 17 on the fusible joint cords 15, preferably perpendicular to the stacking direction D, which promotes the stability of the alternating stack, especially if the latter comprises a large number of electrochemical cells 5 and interconnection plates 6.

[0097] The next step of the method is illustrated in the perspective view of [Fig. 9] and its front view of [Fig. 10]. This step consists of producing the alternating stack of electrochemical cells 5 and interconnection plates 6, with the aim of producing the electrochemical reactor, with the electrically insulating support 1 arranged at the locations provided for the sealing and insulation assemblies 12. As previously, for reasons of clarity, only one elementary pattern of the stack has been illustrated (between two interconnection plates 6), it being understood that the stack comprises as many of these patterns as necessary. The invention allows stacks of significant height, for example of the order of 80 stages of electrochemical cells 5. In addition, in the views of FIGS. 9 and 10, only a portion of the interconnection plates 6 and the electrically insulating support 1 (equipped with its dried and compressed fusible joint cords 15) has been shown.The other portions of the stack, comprising the electrochemical cells 5, known elsewhere, have not been illustrated.

[0098] According to the present embodiment, the installation of the electrically insulating support 1 brings with it the fusible joint cords 15 which it carries. Generally, an electrically insulating support 1 with its fusible joint cords 15 is provided for each stage of the stack, that is to say that such an assembly formed of the electrically insulating support 1 and fusible joint cords 15 are arranged between each pair of interconnection plates 6.

[0099] From this stack assembly, sealing within the electrochemical reactor being manufactured can be achieved.

[0100] The alternating stacking assembly of figures 9 and 10 is preferably carried out in a press which advantageously comprises guide means 18 following the stacking direction D, for each element of the stack (the guide means 18 are shown diagrammatically by axis lines in [Fig. 10]).

[0101] The next operation of the method consists of pressing said alternating stack along the stacking direction D and bringing it to a melting temperature of the fusible joint beads 15. This melting temperature is higher than the melting point of the fusible joint beads 15, so as to obtain the melting of the latter.

[0102] In the present example, the melting temperature of the fusible joint cords 15 is between 850°C and 1000°C (for an electrochemical reactor operating for example at 800°C), and is in any case lower than the operating temperature provided for the electrochemical reactor.

[0103] During this step, the fusible joint beads 15 melt and deform under the effect of the applied pressure.

[0104] The fusible joint thus forms a seal 13 by spreading into the through openings 2 under the effect of the press, and by adhering to the interconnection plates located opposite these through openings. A seal 13 is thus formed, by extending into the through openings 2 of the electrically insulating support 1, and by connecting two interconnection plates 6 through the through openings 2, as illustrated in [Fig. 11].

[0105] These essential operations in the manufacture of the electrochemical reactor are thus carried out, with the sealing and insulation assemblies 12 required to allow the operation of the electrochemical cells 5. The rest of the manufacturing process of the electrochemical reactor (electrical and fluidic connections, etc.) takes place in a conventional manner.

[0106] Figures 12 to 19 illustrate a second embodiment of the manufacturing method according to the invention in which the fusible joint cords 15, rather than being deposited on the electrically insulating support 1, are alternatively deposited on the interconnection plates 6.

[0107] According to this second embodiment, after a first step of producing the electrically insulating support 1, pierced with the through openings 2, a second step consists of depositing at least one fusible joint bead 15 on each interconnection plate 6. The perspective view of [Fig. 12], and its front view of [Fig. 13], illustrate the deposition of the fusible joint beads 15 on one face of a plate interconnection plate 6. The deposition of the fusible joint cords 15 can also take place on both sides of each interconnection plate 6.

[0108] The deposition procedure and the deposited material are the same as in the first embodiment. Similarly, the volume of fusible joint bead 15 deposited is determined in order to fill all the through openings 2, and to adhere to the interconnection plates 6 on either side of each through opening 2 of the electrical insulating supports 1.

[0109] The next step of the method consists of carrying out the operation of hardening the fusible joint beads 15, in this example by evaporation of a solvent using an operation of drying the fusible joint beads 15 or any other suitable method, as for the first embodiment.

[0110] The next step of the method consists of placing this assembly, consisting of an interconnection plate 6 provided with its fusible joint cords 15, under pressure, and compressing the fusible joint cords 15 in the stacking direction D, in the same way as in the first embodiment.

[0111] The result of the operation of compressing the fusible joint beads 15 is illustrated in the front view of [Fig. 14] and in the perspective view of [Fig. 15]. The fusible joint beads 15 thus plastically deformed have a calibrated height and, in this example, a flat surface 17.

[0112] The next step of the method is illustrated in the perspective view of [Fig. 16] and consists of placing the electrically insulating support 1 on the interconnection plate 6 provided with its dried and compressed fusible joint cords 15, with the aim of initiating the formation of an alternating stack with an electrochemical cell 5 (not visible in the partial view of [Fig. 16]), an interconnection plate 6, and the electrically insulating support 1 intended to form the sealing and insulation assembly 12 at the required locations.

[0113] The alternating stacking of electrochemical cells 5 and interconnection plates 6 is continued, with the installation of another interconnection plate 6 provided in the same way with dried and compressed fusible joint cords 15. The perspective view of [Fig. 17] as well as the corresponding front view of [Fig. 18] illustrates an elementary pattern of the stack, in partial view, with an electrically insulating support 1 between two interconnection plates 6.

[0114] From this stack assembly, produced in a press with guiding means following the stacking direction D, the sealing within the electrochemical reactor being manufactured can be achieved in the same way as in the first embodiment, with the press clamping said alternating stack following the stacking direction D, at the melting temperature of the fusible joint beads 15, so that the fusible joint thus forms a seal 13 by spreading in the through openings 2 under the effect of the press, and adhering to the interconnection plates 6 located opposite these through openings 2. A seal 13 is thus formed, extending into the through openings 2 of the electrically insulating support 1, and connecting two interconnection plates 6 through the through openings 2, as illustrated in [Fig. 19].

[0115] This second embodiment makes it possible to limit the handling of the electrically insulating support 1 which may be fragile, this is the case for example when it is made of mica, by transferring certain handling to the interconnection plates 6. This second embodiment also makes it possible to mechanically preserve the electrically insulating support 1, in particular when it is compressible, by avoiding a compression step.

[0116] Alternative embodiments may be envisaged. In particular, the shape of the electrically insulating support, and therefore of the sealing and insulation assembly 12 obtained, may vary and may, for example, consist only of linear sealing barriers, arranged at the appropriate locations around each electrochemical cell 5, rather than in the form of a frame as in the example illustrated. Similarly, the sealing and insulation assemblies 12 may be provided for any type of sealing required between two interconnection plates 6, other than the sealing around the transverse channels 7 and the sealing towards the outside of the reactor.

Claims

Claims

1. Method for manufacturing a solid oxide electrochemical reactor which comprises: - an alternating stack of electrochemical cells (5) and interconnection plates (6), in a stacking direction (D), the electrochemical cells (5) each comprising a layer of solid electrolyte (8) arranged between two layers of electrodes (9, 10), and the interconnection plates (6) comprising electrically conductive plates provided with reaction fluid distribution channels; - at least one transverse channel (7) for circulation of the reaction fluids between the interconnection plates (6); - sealing and insulation assemblies (12) arranged between the interconnection plates (6); this method being characterized in that it comprises the following steps: - production of an electrically insulating support (1) comprising a sheet of electrically insulating material pierced with through openings (2);- depositing at least one electrically insulating fusible joint bead (15) on an element selected from the group consisting of the interconnection plates (6) and the electrically insulating support (1); - carrying out an operation of hardening the fusible joint bead (15); - compressing the fusible joint bead (15) in the stacking direction (D), and plastically deforming it; - producing an alternating stack of electrochemical cells (5) and interconnection plates (6), and arranging the electrically insulating support (1) between two interconnection plates (6); - pressing said alternating stack in the stacking direction (D), and bringing it to a melting temperature of the fusible joint bead (15), so that the fusible joint bead (15) extends into the through openings (2) of the electrically insulating support (1), and forms a seal (13) connecting two interconnection plates (6) through these through openings (2).;

2. Method according to claim 1, characterized in that, in the step of producing the electrically insulating support (1), the through openings (2) are arranged in discontinuous grooves arranged along joining lines.

3. Method according to claim 2, characterized in that, in the step of production of the electrically insulating support (1), said sheet of electrically insulating material is further pierced with a central window (3) for the positioning of an electrochemical cell (5), the joining lines being arranged around this central window (3).

4. Method according to one of claims 2 or 3, characterized in that, in the step of producing the electrically insulating support (1), said sheet of electrically insulating material is further pierced with at least one lateral window (4) intended for the passage of the transverse channel (7) for circulation of the reaction fluids, the joining lines being arranged around this lateral window (4).

5. Method according to one of claims 2 to 4, characterized in that, in the step of producing the electrically insulating support (1), several parallel joining lines are arranged side by side.

6. Method according to claim 5, characterized in that said parallel joining lines are formed of discontinuous grooves which comprise discontinuities arranged in staggered rows.

7. Method according to one of the preceding claims, characterized in that the electrically insulating support (1) comprises a single-piece frame.

8. Method according to one of the preceding claims, characterized in that, in the step of depositing at least one fusible joint bead (15), fusible joint beads (15) are deposited on the edge of each through opening (2).

9. A method according to claim 8, characterized in that, in the step of compressing the fusible joint bead (15), all the fusible joint beads (15) are calibrated to the same height (H).

10. Method according to one of the preceding claims, characterized in that, in the step of compressing the fusible joint bead (15), the compression is carried out by a press comprising jaws (16) extending along a flat surface substantially perpendicular to the stacking direction (D).

11. Method according to one of the preceding claims, characterized in that, in the step of compressing the fusible joint bead (15), the compression is carried out by applying a predetermined force.

12. Method according to one of claims 1 to 10, characterized in that, in the step of compressing the fusible joint bead (15), the compression is carried out by applying a predetermined displacement.

13. A method according to one of the preceding claims, characterized in that, in the step of compressing the fusible joint bead (15), the bead of fusible joint (15) is plastically deformed to present flat bearing surfaces (17) substantially perpendicular to the stacking direction (D).

14. Method according to one of the preceding claims, characterized in that, in the step of producing an alternating stack of electrochemical cells (5) and interconnection plates (6), the stack is produced in a press comprising guide means (18) following the stacking direction (D), the step of compressing the fusible joint bead (15) being carried out in this same press.

15. Method according to one of the preceding claims, characterized in that the fusible joint bead (15) comprises: a glass, or glass-ceramic, or ceramic powder; a solvent; and a binder.

16. Method according to one of the preceding claims, characterized in that: in the step of depositing at least one fusible joint bead (15), the fusible joint bead (15) is deposited on an interconnection plate (6); and in the step of compressing the fusible joint bead (15), the compression is carried out on the assembly formed by this interconnection plate (6) and the fusible joint bead (15); and in the step of producing an alternating stack of electrochemical cells (5) and interconnection plates (6), the fusible joint bead (15) is brought into contact with the electrically insulating support (1).

17. Method according to one of claims 1 to 15, characterized in that: in the step of depositing at least one fusible joint bead (15), the fusible joint bead (15) is deposited on the electrically insulating support (1); and in the step of compressing the fusible joint bead (15), the compression is carried out on the assembly formed by this electrically insulating support (1) and the fusible joint bead (15); and in the step of producing an alternating stack of electrochemical cells (5) and interconnection plates (6), the fusible joint bead (15) is brought into contact with an interconnection plate (6).

18. A method according to claim 17 when dependent on claim 2, characterized in that, in the step of depositing at least one fusible joint bead (15), the fusible joint bead (15) is deposited on the areas between the joint lines.

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