Reinforced interconnector for electrochemical device and corresponding manufacturing method

Abstract

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

Description

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

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

[0002] The invention is of particular interest, in no way limiting, in solid oxide electrochemical devices, in particular high-temperature electrolysers. State of the art

[0003] The electrochemical devices known in the prior art generally comprise stacks of electrochemical cells which are connected to each other by interconnection members, 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 due to finning, in particular when they comprise metal plates or sheets.

[0006] The thinning of the interconnectors leads to a reduction in the lifetime of the device and a degradation of its performance, in particular by generating pressure losses in the fluid channels formed by the interconnectors. Statement 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 electrolyser or high-temperature fuel cell, the assembly comprising: - an electrochemical cell, - an interconnector which comprises a first surface and a second surface each forming an alternation of concave parts and convex parts, - force transmission elements which each extend into a respective one of the concave parts formed by the first surface of the interconnector and which are 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: - first channels which are each delimited by a respective one of said convex parts formed by the first surface of the interconnector and by the electrochemical cell, - second channels which are each delimited by a respective one of said 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 fining. 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 filler material such as a foam. In one embodiment, the interconnector comprises at least one corrugated plate. In particular, the interconnector may comprise a portion forming corrugations which may be obtained by stamping or hydroforming. In other words, the interconnector may comprise 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, among other things, ferritic steel. In one embodiment, the interconnector material comprises chromium or a chromium alloy. Alternatively, the interconnector material may comprise nickel or a nickel alloy. In one embodiment, the interconnector comprises 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 electrolyser.

[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 a respective one of said force transmission elements of each of said assemblies.

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

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

[0033] In one embodiment, the shaping step comprises 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 comprises 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 characteristics of the invention will appear on reading the detailed, non-limiting description which follows. Brief description of the figures

[0038] The following detailed description refers to the accompanying drawings in which: - [Fig.l] is a schematic view of an electrochemical device comprising stacks of electrochemical cells and interconnectors; - [Fig.2] is a schematic view of part of a stack of an electrochemical device, showing an electrochemical cell enclosed between two interconnectors, the cell comprising two electrodes and an electrolyte disposed between the electrodes; - [Fig.3] is a schematic view of an interconnector comprising a plate forming a corrugated portion which defines fluid channels; - [Fig.4] is a partial schematic sectional view of the corrugated portion of the interconnector of [Fig.3]; - [Fig.5] is a schematic 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 sectional view of a part of the stack of [Fig.5] forming an assembly which comprises one of the electrochemical cells, one of the interconnectors and a row of said reinforcing elements; - [Fig.7] is a schematic sectional view of part of a plate and wires arranged in a stamping or hydroforming press tool, before stamping or hydroforming; - [Fig.8] is a schematic sectional view of the plate and wires arranged in the tooling of [Fig.7] after stamping or hydroforming; - [Fig.9] is a schematic sectional view of the plate and wires after stamping or hydroforming.

[0039] Common references are used in the various figures to designate identical or similar elements. Detailed description of embodiments

[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 shown in a simplified manner in [Fig.l].

[0042] In this non-limiting example, the 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.l], the device 1 comprises two stacks 2 which each comprise 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 in the direction D3 which is here vertical.

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

[0047] In a manner known per se, the cell 3 comprises two electrodes 6 and 7, respectively forming 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. To do this, water vapor 10 is introduced at the cathode 7 which ensures the electrochemical reduction reaction resulting in a 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 which causes a migration of the superoxide ions 12 from the cathode 7 to the anode 6 through the electrolyte 8. At the anode 6, the superoxide ions 12 are oxidized resulting in a production of dioxygen 13 in gaseous form.

[0048] The interconnector 4 arranged on the anode 6, that is to say the one located 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 arranged on the cathode 7, that is to say the one located 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 direction DI.

[0049] Of course, the interconnector 4 arranged on the cathode 7 of the cell 3 of [Fig. 2] can also comprise first channels (not shown in [Fig. 2]) which open opposite the anode of another electrochemical cell (not shown in [Fig. 2]) of the stack 2, in order to evacuate a flow of dioxygen produced by this other cell. Similarly, the interconnector 4 arranged on the anode 6 of the cell 3 of [Fig. 2] can also comprise second channels (not shown in [Fig. 2]) which open opposite the cathode of another electrochemical cell (not shown in [Fig. 2]) of the stack 2, in order to evacuate 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 the surface 21 along 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 plate of the interconnector 4 is made of chrome or a chrome alloy.

[0054] The plate forming the interconnector 4 of figures 3 and 4 has been shaped so as to have 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 precisely, 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, 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”. In a non-limiting manner, the bearing surfaces 21S and 22S are in this example planar and extend parallel to the directions DI and D2.

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

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

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

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

[0062] In a non-limiting manner, the reinforcing elements 30 may comprise a chromium alloy, typically a ferritic steel of the “AISI 441” type.

[0063] The configuration of [Fig.5] is an assembled configuration which allows the device 1 formed by such a stack 2 to be put into service.

[0064] In the configuration of [Fig.5], the stack 2 is subjected to a force of pressing of its different components which is exerted globally in 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 the one hand with the first surface 21 of one of the interconnectors 4 and, on the other hand, 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 in 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 fluid channels 60 and 62 which each extend along the direction DI and which are organized in a double row.

[0067] The channels 60 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.

[0068] Thus, in each of the first rows of channels 60, the channels 60 of this row are spaced from each other in the direction D2. In each of the second rows of channels 60, the channels 60 of this 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 this row are spaced from each other in the direction D2. In each of the second rows of channels 62, the channels 62 of this 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 correspond here to said first channels and are intended to convey dioxygen, while the channels 60 correspond to said second channels and are intended to convey dihydrogen.

[0072] The reinforcing elements 30 of the stack 2 of [Fig. 5] are also organized in a double row, so as to 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.

[0073] Thus, in each of the first rows of reinforcing elements 30, the reinforcing elements 30 of this row are spaced from each other in the direction D2. In each of the second rows of reinforcing elements 30, the reinforcing elements 30 of this 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 a 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 respective of the cells 3 for the other rows of channels 60, - on a second side along D3, by a respective one of the concave parts 22A formed by the surface 22 of a respective one of the interconnectors 4, - on either side along D2, by portions of the corresponding interconnector 4 which connect two respective ones of the bearing surfaces 21S to a corresponding convex part 21B.

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

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

[0077] In the embodiment of [Fig. 5], the channels 60 and 62 are empty, that is to say they do not receive any filling material. The channels 60 and 62 are in particular devoid of foam.

[0078] The configuration of [Fig.5] thus makes it possible to define force paths Fl which extend generally parallel to the direction D3.

[0079] More precisely, each of these force paths F1 is formed by a respective one of said second rows (columns) of reinforcing elements 30 which make it possible to support the mechanical load applied to the stack 2.

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

[0081] The reinforcing elements 30 thus ensure the transmission of the plating force and make it possible to optimize the distribution of the mechanical loads in the stack 2.

[0082] Of course, the distribution of the mechanical loads in the stack 2 and / or the circulation of the gas flows in the channels 60 and / or 62 can be adjusted as needed by adjusting one or more parameters chosen from a list including, but not limited to: - the dimension of the reinforcement elements 30, - the dimension of the support surfaces 21S and / or 22S of the interconnectors 4, - the number and distribution of the reinforcing elements 30 in the 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 in order to form an assembly E1 as described above.

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

[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 comprises hollow parts 81, relative to said surface of the mold / die 80 on which the plate 4 is arranged.

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

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

[0089] The mold / die 80 and the counter-mold 85 are configured so as to shape the plate 4 and simultaneously shape the wires 30 so as to obtain the subassembly illustrated in [Fig.9], in which the plate 4 and the wires 30 thus shaped form the interconnector and the reinforcing elements of an assembly E1 as illustrated in [Fig.6].

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

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

[0092] In a variant not shown, reinforcing elements 30 may be otherwise arranged and / or shaped on an interconnector 4 previously stamped or hydroformed.

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

[0094] Alternatively, the concave and convex portions of an interconnector 4 may be formed using any other technique.

[0095] In an alternative embodiment, not shown, one or more of the channels 60 and / or 62 may comprise 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

Claims

1. Assembly (El) for an electrochemical device (1), in particular for a high-temperature electrolyzer or a high-temperature fuel cell, the assembly (El) comprising: - an electrochemical cell (3), - an interconnector (4) which comprises a first surface (21) and a second surface (22) each forming an alternation of concave portions (21A, 22A) and convex portions (21B, 22B), - force transmission elements (30) which each extend into a respective one of the concave portions (21A) formed by the first surface (21) of the interconnector (4) and which are 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: - first channels (62) which are each delimited by a respective one of said convex parts (21B) formed by the first surface (21) of the interconnector (4) and by the electrochemical cell (3), - second channels (60) which are each delimited by a respective one of said concave parts (22A) formed by the second surface (22) of the interconnector (4) and which open out on one side of the assembly (El) intended to be arranged on another electrochemical cell.,

2. Assembly (El) according to claim 1, in which 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, in which the interconnector (4) comprises at least one corrugated plate.

5. An 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 electrolyser 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 a respective one 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 comprises a hydroforming and / or stamping step.

10. A 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).

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