Reinforced interconnector for electrochemical device and corresponding manufacturing process

Abstract

High-temperature electrolyzer comprising corrugated interconnectors (4) equipped with reinforcing rods (30). Manufacturing process relating thereto. Figure for the abstract: Fig. 5

Description

Title of the invention: Reinforced interconnector for electrochemical device and corresponding manufacturing process. Technical field

[0001] The present invention relates to the field of electrochemical devices and finds applications in particular in the sectors of renewable energy production, especially dihydrogen.

[0002] The invention is of particular, but not limiting, interest in solid oxide electrochemical devices, especially high-temperature electrolyzers. Prior art

[0003] Electrochemical devices known in the prior art generally include stacks of electrochemical cells which are connected together by interconnecting elements, also called "interconnectors".

[0004] In a high-temperature electrolyzer, the interconnectors are exposed for prolonged periods to high temperatures which are typically between 600°C and 850°C.

[0005] Under these conditions, the interconnectors are likely to deform by sagging, in particular when they include metal plates or sheets.

[0006] The fining of the interconnectors leads to a reduction in the lifespan of the device and a degradation of its performance, in particular by generating pressure losses in the fluidic channels formed by the interconnectors. Description of the invention

[0007] The invention aims to remedy the aforementioned drawbacks.

[0008] To this end, the invention relates to an assembly for an electrochemical device, in particular for a high-temperature electrolyzer or high-temperature fuel cell, the assembly comprising: - an electrochemical cell, - an interconnector comprising a first surface and a second surface, each forming an alternation of concave and convex parts, - force transmission elements, each extending into one of the respective concave parts formed by the first surface of the interconnector, and interposed between the interconnector and the electrochemical cell so as to be able to transmit a force exerted on one of the interconnector and the electrochemical cell to the other of the interconnector and the electrochemical cell,

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[0023] the whole forming: - the first channels, each delimited by one of the respective convex parts formed by the first surface of the interconnector and by the electrochemical cell, - of the second channels, each delimited by one of the respective concave parts formed by the second surface of the interconnector and which open on one side of the assembly intended to be placed on another electrochemical cell. Such force transmission elements, also called "reinforcing elements", make it possible to increase the mechanical resistance of the assembly and reduce the effects of sagging. The force transmission elements make it possible, in particular, to improve the force paths in the device, by adequately distributing the mechanical load. The invention also makes it possible to improve the electrical contact between the interconnector and the cell. In one embodiment, the force transmission elements form rods or bars. Preferably, the force transmission elements comprise a metallic material. In one embodiment, the first channels and / or the second channels are devoid of a filling material. In particular, the first channels and / or the second channels may be devoid of a filling material such as foam. In one embodiment, the interconnector includes at least one corrugated plate. In particular, the interconnector may include a part forming corrugations which can be obtained by stamping or hydroforming. In other words, the interconnector may include at least one stamped plate or hydroformed so as to form such undulations or, more generally, hollow parts. In one embodiment, the interconnector comprises a metallic material. The interconnector material may include, in particular, ferritic steel. In one embodiment, the interconnector material comprises chromium or a chromium alloy. Alternatively, the interconnector material may include nickel or a nickel alloy. In one embodiment, the interconnector includes a coating.

[0024] Such a coating may comprise a metallic material, preferably nickel or a nickel alloy.

[0025] Such a material of the interconnector and / or its possible coating makes it possible to increase the conductivity.

[0026] The invention also relates to an electrochemical device.

[0027] According to a first variant, the electrochemical device is a high-temperature electrolyzer.

[0028] According to a second variant, the electrochemical device is a high-temperature fuel cell.

[0029] The device of the invention comprises one or more assemblies as defined above.

[0030] In one embodiment, several of said assemblies are stacked so as to form one or more force paths which are each formed by one of the respective force transmission elements of each of said assemblies.

[0031] According to another aspect, the invention relates to a method for manufacturing and / or assembling such an assembly.

[0032] In one embodiment, the method includes a step of shaping the interconnector so as to form said concave and convex parts.

[0033] In one embodiment, the shaping step includes a hydroforming step and / or a stamping step.

[0034] Such a shaping step makes it possible to simplify the manufacture of the interconnector.

[0035] In one embodiment, the method includes a step of arranging said force transmission elements on said first surface of the interconnector.

[0036] Particularly advantageously, the shaping step can be carried out with the force transmission elements arranged on the first surface of the interconnector.

[0037] Other advantages and features of the invention will become apparent from the following detailed, non-limiting description. Brief description of the figures

[0038] The following detailed description refers to the attached drawings on which: - [Fig.1] is a schematic view of an electrochemical device comprising stacks of electrochemical cells and interconnectors; - Figure 2 is a schematic view of part of a stack of an electrochemical device, showing an enclosed electrochemical cell between two interconnectors, the cell comprises two electrodes and an electrolyte arranged between the electrodes; - [Fig.3] is a schematic view of an interconnector comprising a plate forming a corrugated part which defines fluidic channels; - [Fig.4] is a partial schematic cross-sectional view of the corrugated part of the interconnector of [Fig.3]; - [Fig.5] is a schematic cross-sectional view of part of a stack of an electrochemical device according to the invention, this stack comprising five electrochemical cells, five interconnectors, two terminal plates and reinforcing elements arranged between the interconnectors and the cells; - [Fig.6] is a schematic cross-sectional view of part of the stack of [Fig.5] forming an assembly which includes one of the electrochemical cells, one of the interconnectors and a row of said reinforcing elements; - the [Fig.7] is a schematic cross-sectional view of part of a plate and wires arranged in a stamping or hydroforming press tooling, before stamping or hydroforming; - [Fig.8] is a schematic cross-sectional view of the plate and wires arranged in the tooling of [Fig.7] after stamping or hydroforming; - [Fig.9] is a schematic cross-sectional view of the plate and wires after stamping or hydroforming.

[0039] Common references are used on the different figures to designate identical or analogous elements. Detailed description of implementation methods

[0040] Figures 1 to 6 include a reference frame defining orthogonal directions D1, D2 and D3.

[0041] An electrochemical device 1 according to the invention is represented in a simplified manner in [Fig.1].

[0042] In this non-limiting example, device 1 is a solid oxide electrolyzer configured to produce dihydrogen by gas phase electrolysis, i.e. a high temperature electrolyzer.

[0043] As an indication, electrolysis can be carried out at a temperature between 700°C and 850°C.

[0044] In the simplified example of [Fig. 1], device 1 comprises two stacks 2 which each include electrochemical cells, in this case electrolysis cells, between which interconnectors are interposed.

[0045] In each of the stacks 2, the electrochemical cells and the interconnectors are stacked alternately along the direction D3 which is vertical here.

[0046] Figure 2 schematically shows part of a stack 2 including an electrochemical cell 3 and two interconnectors 4 which are stacked along the direction D3. The cells and interconnectors of the stacks 2 of the device 1 of Figure 1 can be configured as described below with reference to Figure 2.

[0047] In a manner known per se, the cell 3 comprises two electrodes 6 and 7, forming respectively an anode and a cathode, as well as an electrolyte 8 disposed between the electrodes 6 and 7. The cell 3 is configured to dissociate water molecules into dihydrogen and dioxygen by redox reaction. To this end, water vapor 10 is introduced at the cathode 7, which carries out the electrochemical reduction reaction resulting in the production of dihydrogen 11 in gaseous form and superoxide ions 12. A potential difference is imposed between the anode 6 and the cathode 7, creating an electric field that causes the superoxide ions 12 to migrate from the cathode 7 to the anode 6 through the electrolyte 8. At the anode 6, the superoxide ions 12 are oxidized, resulting in the production of dioxygen 13 in gaseous form.

[0048] The interconnector 4 located on the anode 6, i.e., the one situated towards the bottom of [Fig. 2], comprises channels (not shown in [Fig. 2]), called "first channels," which open opposite the anode 6 so as to evacuate the flow of dioxygen 13 thus produced. The interconnector 4 located on the cathode 7, i.e., the one situated towards the top of [Fig. 2], comprises channels (not shown in [Fig. 2]), called "second channels," which open opposite the cathode 7 so as to evacuate the flow of dihydrogen 11 thus produced. In this example, these different channels extend along the DI direction.

[0049] Of course, the interconnector 4 located on the cathode 7 of cell 3 in [Fig. 2] can also include first channels (not shown in [Fig. 2]) opening opposite the anode of another electrochemical cell (not shown in [Fig. 2]) in the stack 2, in order to discharge a flow of dioxygen produced by this other cell. Similarly, the interconnector 4 located on the anode 6 of cell 3 in [Fig. 2] can also include second channels (not shown in [Fig. 2]) opening opposite the cathode of another electrochemical cell (not shown in [Fig. 2]) in the stack 2, in order to discharge a flow of dihydrogen produced by this other cell.

[0050] The invention relates more specifically to an interconnector 4 for such a stack 2 and to its cooperation with one or more electrochemical cells 3 of this stack 2.

[0051] A non-limiting example of an interconnector 4 according to the invention is shown in Figures 3 and 4.

[0052] In this example, the interconnector 4 is in the form of a plate or sheet having a first surface 21, which in this example is intended to come into contact with an anode of an electrochemical cell, and a second surface 22, opposite to the surface 21 according to D3, this second surface 22 being in this example intended to come into contact with a cathode of another electrochemical cell.

[0053] In this non-limiting example, the interconnector plate 4 is made of chrome or a chrome alloy.

[0054] The plate forming the interconnector 4 of figures 3 and 4 has been shaped to present a corrugated part 25, that is to say a part comprising an alternation, in this case along the direction D2, of concave and convex parts.

[0055] More specifically, the surfaces 21 and 22 of the interconnector 4 each have an alternation of concave parts 21A / 22A and convex parts 21B / 22B, so that the concave parts 21A of the surface 21 correspond to the convex parts 22B of the surface 22 and, conversely, that the convex parts 21B of the first surface 21 correspond to the concave parts 22A of the second surface 22 (see [Fig.4]).

[0056] In this example, the concave parts 21A / 22A of the first, respectively of the second, surface define hollows along D3 with respect to a part of this first, respectively second, surface which extends around the corrugated part 25 of the interconnector 4.

[0057] With reference to [Fig. 4], the concave portions 21A of the interconnector 4 each form surface elements 21S, also called "bearing surfaces". Similarly, the convex portions 22B of the interconnector 4 each form surface elements 22S, also called "bearing surfaces". Without limitation, the bearing surfaces 21S and 22S are in this example planar and extend parallel to the directions DI and D2.

[0058] Figure 5 shows part of a stack 2 according to the invention.

[0059] In this non-limiting example, stacking 2 of [Fig. 5] comprises cells electrochemical 3 as described above, interconnectors 4 similar to that of figures 3 and 4, force transmission elements 30, also called "reinforcing elements", end plates 40 and 42, and grids forming contact elements 50.

[0060] With reference to figures 4 to 6, each of the reinforcing elements 30 extends into one of the respective concave parts 21A formed by the surface 21 of the interconnectors 4, so as to bear on one of the respective bearing surfaces 21S.

[0061] In this example, the reinforcing elements 30 form metal rods or bars, each extending parallel to the direction DI.

[0062] By way of non-limitation, the reinforcing elements 30 may include a chromium alloy, typically a ferritic steel of the type “AISI 441”.

[0063] The configuration of [Fig.5] is an assembled configuration which allows the commissioning of the device 1 formed by such a stack 2.

[0064] In the configuration of [Fig.5], the stack 2 is subjected to a clamping force on its various components which is exerted globally along the direction D3 and which can be exerted on the stack 2 by conventional clamping means (not shown).

[0065] With reference to figures 4 to 6, when the components of the stack 2 are assembled according to the configuration illustrated in [Fig.5], each of the reinforcing elements 30 is in contact on one side with the first surface 21 of one of the interconnectors 4 and, on the other side, with one of the electrochemical cells 3, in this example with the anode of this cell 3, so that the anode of each of the cells 3 is at a non-zero distance along the direction D3 from the convex parts 21B formed by the first surface 21 of the corresponding interconnector 4.

[0066] In this configuration, the stack 2 forms fluidic channels 60 and 62 which each extend along the DI direction and which are arranged in a double row.

[0067] The channels 60 form, on the one hand, first rows, also called "rows", which are spaced from each other in the direction D3 and, on the other hand, second rows, also called "columns", which are spaced from each other in the direction D2.

[0068] Thus, in each of the first rows of channels 60, the channels 60 of that row are spaced from each other in the direction D2. In each of the second rows of channels 60, the channels 60 of that row are spaced from each other in the direction D3.

[0069] Similarly, the channels 62 form on the one hand first rows, also called "lines", which are spaced from each other in the direction D3 and, on the other hand, second rows, also called "columns", which are spaced from each other in the direction D2.

[0070] Thus, in each of the first rows of channels 62, the channels 62 of that row are spaced from each other in the direction D2. In each of the second rows of channels 62, the channels 62 of that row are spaced from each other in the direction D3.

[0071] In this example and with reference to the description of [Fig.2] above, the channels 62 here correspond to the said first channels and are intended to carry dioxygen, while the channels 60 correspond to the said second channels and are intended to carry dihydrogen.

[0072] The reinforcement elements 30 of the stack 2 of [Fig.5] are also arranged in a double row, so as to form on the one hand first rows, also called "rows", which are spaced from each other in the direction D3 and, on the other hand, second rows, also called "columns", which are spaced from each other in the direction D2.

[0073] Thus, in each of the first rows of reinforcement elements 30, the reinforcement elements 30 of that row are spaced from each other in the direction D2. In each of the second rows of reinforcement elements 30, the reinforcement elements 30 of that row are spaced from each other in the direction D3.

[0074] With reference to Figures 4 and 5, for each of the first rows of channels 60, the channels 60 are each delimited: - on the first side according to D3, either by the end plate 42 for the row located towards the bottom of [Fig.5], or by the cathode of one of the respective cells 3 for the other rows of channels 60, - on a second side according to D3, by one of the respective concave parts 22A formed by the surface 22 of one of the respective interconnectors 4, - on either side along D2, by portions of the corresponding interconnector 4 which connect two respective bearing surfaces 21S to a corresponding convex part 21B.

[0075] With further reference to Figures 4 and 5, for each of the first rows of channels 62, the channels 62 are each delimited: - on the first side along D3, by one of the respective convex parts 21B formed by the surface 21 of one of the respective interconnectors 4, - on a second side along D3, by the anode of one of the respective cells 3, - on a first side along D2, by one of the reinforcement elements 30, - on a second side along D2, by another of the reinforcement elements 30.

[0076] The stack 2 of [Fig.5] thus comprises a stacking along D3 of several sets El such as that illustrated in isolation in [Fig.6], each of these sets El comprising one respective of the interconnectors 4 of this stack 2, one respective of the cells 3 of this stack 2 and one respective of said first rows of reinforcement elements 30.

[0077] In the embodiment of [Fig. 5], channels 60 and 62 are empty, i.e., they do not receive any filling material. Channels 60 and 62 are specifically free of foam.

[0078] The configuration of [Fig.5] thus allows the definition of effort paths Fl which extend globally parallel to the direction D3.

[0079] More specifically, each of these force paths Fl is formed by one of the respective second rows (columns) of reinforcement elements 30 which enable the mechanical load applied to the stack 2 to be supported.

[0080] Schematically considering that said clamping force is exerted on the stack 2 from top to bottom of [Fig. 5], the force thus passes successively from plate 40 to: - the contact elements 50 interposed between the plate 40 and the assembly El located at the top of the [Fig.5], - cell 3 of this set El, - the 30 reinforcement elements of this El assembly, - the bearing surfaces formed by the concave parts of the first surface and the convex parts of the second surface of interconnector 4 of this assembly El, - the contact elements 50 interposed between this set El and the adjacent set El, - and so on up to plate 42.

[0081] The reinforcing elements 30 thus ensure the transmission of the clamping force and allow the optimization of the distribution of mechanical loads in the stack 2.

[0082] Of course, the distribution of mechanical loads in the stack 2 and / or the circulation of gas flows in the channels 60 and / or 62 can be adjusted as needed by manipulating one or more parameters chosen from a list including, but not limited to: - the dimension of the reinforcement elements 30, - the dimensions of the bearing surfaces 21S and / or 22S of the interconnectors 4, - the number and distribution of the 30 reinforcement elements in stack 2, - the distance along D3 between the support surfaces 21S and the convex parts 21B formed by the surface 21 of the interconnectors 4, - the distance along D3 between the concave parts 22A and the convex parts 22B formed by the surface 22 of the interconnectors 4.

[0083] The invention provides a method for manufacturing and assembling an interconnector 4 and reinforcing elements 30 to form an assembly El as described above.

[0084] Figures 7 to 9 illustrate a non-limiting example of a process.

[0085] With reference to [Fig.7], the interconnector 4 is initially in the form of a metal plate having a flat surface 22 arranged on a surface of a mold or die 80 of a stamping or hydroforming press tool.

[0086] The mold / die 80 includes hollow parts 81, relative to said surface of the mold / die 80 on which the plate 4 is disposed.

[0087] In this example, metal wires intended to form the reinforcing elements 30 initially have an overall cylindrical geometry and are arranged on the surface 21 of the plate 4 so as to be arranged each at the level of one of the respective hollow parts 81 of the mold 80.

[0088] The tooling includes a counter-mold 85 which is moved in the direction of the mold 80, from an initial configuration as illustrated in [Fig.7] in which the counter-mold 85 is away from the mold 80, to the configuration illustrated in [Fig.8].

[0089] The mold / matrix 80 and the counter-mold 85 are configured so as to conform the plate 4 and simultaneously conform the wires 30 so as to obtain the sub-assembly illustrated in [Fig.9], in which the plate 4 and the wires 30 thus formed form the interconnector and the reinforcing elements of an assembly El as illustrated in [Fig.6].

[0090] The stamping or hydroforming operation illustrated in [Fig.8] thus makes it possible to deform the plate 4 in such a way as to form the said concave and convex parts described above with reference to [Fig.4].

[0091] Numerous variations can be made to the preceding description, particularly concerning the geometry and / or material of the various components described above. For example, the invention can be implemented with a nickel interconnector 4. Alternatively, the interconnector 4 can be made of ferritic stainless steel or another ferritic alloy and include a coating comprising nickel or a nickel alloy.

[0092] In an unshown variant, reinforcement elements 30 can be otherwise arranged and / or shaped on a previously stamped or hydroformed interconnector 4.

[0093] For another example, reinforcing elements 30 can be attached to an interconnector 4, before or after stamping or hydroforming, for example by welding.

[0094] Alternatively, the concave and convex parts of an interconnector 4 can be formed according to any other technique.

[0095] In an alternative embodiment, not shown, one or more of the channels 60 and / or 62 may include a foam or other gas-permeable filling material.

[0096] More generally, the invention can be implemented to form an electrochemical device different from that described above, for example a high-temperature fuel cell.

Claims

Demands

1. Assembly (El) for an electrochemical device (1), in particular for a high-temperature electrolyzer or high-temperature fuel cell, the assembly (El) comprising: - an electrochemical cell (3), - an interconnector (4) comprising a first surface (21) and a second surface (22) each forming an alternation of concave parts (21A, 22A) and convex parts (21B, 22B), - force transmission elements (30) each extending into one of the respective concave parts (21A) formed by the first surface (21) of the interconnector (4) and interposed between the interconnector (4) and the electrochemical cell (3) so as to be able to transmit a force (Fl) exerted on one of the interconnector (4) and the electrochemical cell (3) to the other of the interconnector (4) and the electrochemical cell (3),the assembly (El) forming: - the first channels (62) which are each delimited by one of the respective convex parts (21B) formed by the first surface (21) of the interconnector (4) and by the electrochemical cell (3), - the second channels (60) which are each delimited by one of the respective concave parts (22A) formed by the second surface (22) of the interconnector (4) and which open onto one side of the assembly (El) intended to be placed on another electrochemical cell.

2. Assembly (El) according to claim 1, wherein the force transmission elements (30) form rods or bars, preferably comprising a metallic material.

3. Assembly (El) according to claim 1 or 2, wherein the first channels (62) and / or the second channels (60) are devoid of a filling material such as a foam.

4. Assembly (El) according to any one of claims 1 to 3, wherein the interconnector (4) comprises at least one corrugated plate.

5. Assembly (El) according to any one of claims 1 to 4, wherein the interconnector (4) comprises a metallic material and / or a coating comprising a metallic material.

6. Electrochemical device (1), for example high-temperature electrolyzer or high-temperature fuel cell, comprising one or more assemblies (El) according to any one of claims 1 to 5.

7. Device (1) according to claim 6, wherein several of said assemblies (El) are stacked so as to form one or more force paths (Fl) which are each formed by one respective of said force transmission elements (30) of each of said assemblies (El).

8. Method of manufacturing an assembly (El) according to any one of claims 1 to 5, comprising a step of shaping the interconnector (4) so ​​as to form said concave and convex parts.

9. A method according to claim 8, wherein the shaping step includes a hydroforming and / or stamping step.

10. Method according to claim 8 or 9, wherein the shaping step is carried out with the force transmission elements (30) arranged on the first surface (21) of the interconnector (4).