Guide rod for the fabrication of a solid oxide electrochemical system and method for manufacturing such a system

Abstract

The invention relates to a guide rod (200) for the manufacture of a solid oxide electrochemical system (100), said electrochemical system comprising a stack (130) of unit devices (170), each device comprising at least one interconnector (150), a solid oxide electrochemical cell (160) and a spacer (140) interposed between said interconnector and an interconnector of an adjacent device, each interconnector and each spacer having at least one perforation (152, 142), preferably at least two perforations, allowing the passage of said associated guide rod, in order to maintain the stack in a predefined position, said manufacture comprising a step of compressing the stack (130) obtained during the stacking step, said guide rod being made up of an assembly of a first (210) and a second (220) sections,said assembly being reversible so as to allow the separation of said sections at the end of the compression step. The invention also relates to the manufacture of an electrochemical system. Figure [3],

Description

Title of the invention: Guide rod for manufacturing a solid oxide electrochemical system and method of manufacturing such a system Technical field

[0001] The present invention relates to a guide rod for the manufacture of a solid oxide electrochemical system.

[0002] The invention also relates to a method for manufacturing a solid oxide electrochemical system, using such a rod.

[0003] The field of the invention is generally the field of solid oxide electrochemical systems, of the electrolyzer or fuel cell type. State of the art

[0004] A solid oxide electrochemical system, of the electrolyzer or fuel cell type, comprises a stack of unit devices also called SRU for "Single Repetitive Unit". Each unit device of the stack comprises an electrically conductive interconnector and a solid oxide electrochemical cell arranged between said interconnector and another interconnector, for example of an adjacent unit device.

[0005] It is necessary to correctly position the various elements of the unitary devices, in order to ensure electrical continuity between each interconnector and the electrochemical cell, while avoiding direct electrical contact between two adjacent interconnectors so as not to short-circuit the electrochemical cell.

[0006] In operation, the stack is brought to a high operating temperature, for example between 600°C and 850°C in the case of a solid oxide electrolyser. Consequently, it is necessary for the parts making up the electrolyser to be resistant to these temperatures and to have similar expansion behaviours, otherwise the electrolyser will be damaged. In addition, the electrolyser operates in a redox and humid atmosphere, which requires chemical compatibility of the parts making it up.

[0007] Due to these constraints, in current architectures, electrical insulation is provided by a layer of electrical insulation placed between the interconnectors, and which is generally made of a mica-based material.

[0008] In addition, it is also necessary to correctly position the various constituent elements of the electrochemical devices, in order to ensure circulation of gas flow between the cell and each interconnector. It is also necessary to maintain a gas seal between the interconnectors, around the electrochemical cell. trophic.

[0009] This is why it is known to achieve gas sealing by means of a multitude of sealing cords, generally made of glass-ceramics, deposited between the parts forming the electrochemical device.

[0010] It is also known during the manufacture of the stack to compress the stack of unit devices, for example by pressing, so that the electrochemical cells are pressed against each other. This has the effect of improving the electrical conductivity and reducing the contact resistance between the electrochemical cells.

[0011] However, during compression which is carried out at high temperatures so as to melt joints, for example slip, to obtain the sealing beads, it is necessary to monitor this compression and in particular to ensure that the stack does not deform laterally, which could compromise the electrical insulation as well as the sealing.

[0012] In order to hold the stack of unitary devices in place, one or more rods, for example made of ceramics, can be used passing through this stack.

[0013] However, due to the reduction in the height of the stack after compression, it is necessary to eliminate the portion of the rods which protrude from the stack.

[0014] To do this, it is possible to saw off the portion of the stems that protrudes at the base.

[0015] However, this operation is energy-intensive, since it requires equipment to saw the material, generally ceramic, and remove the portion of the rods that protrudes.

[0016] Furthermore, this operation is polluting since it generates dust, shavings, and vapors from the heating of the cutting lubricant.

[0017] Finally, this operation is expensive since a dedicated machining station must be provided.

[0018] An aim of the present invention is to remedy at least one of the drawbacks aforementioned.

[0019] Another aim of the invention is also to propose an alternative which makes it possible to limit, or even eliminate, waste, in order to be able to avoid the operations of recycling the excess length of the rods. Statement of the invention

[0020] For this purpose, the invention relates to a guide rod for the manufacture of a solid oxide electrochemical system, said electrochemical system comprising a stack of unit devices, each unit device comprising at least one interconnector, a solid oxide electrochemical cell and a spacer interposed between said interconnector and an interconnector of an adjacent device, each interconnector and each spacer having at least one perforation, preferably at least one perforation.

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[0032] at least two perforations, allowing the passage of said associated guide rod, in order to maintain the stack in a predefined position, said manufacturing comprising a step of high temperature compression of the stack obtained during the stacking step, characterized in that: - said guide rod consists of an assembly of a first and a second section, said assembly being reversible so as to allow the separation of said sections at the end of the compression step, - said guide rod is electrically insulating and resistant to high temperatures. Various embodiments of the invention are provided, integrating, according to all of their possible combinations, the various optional characteristics set out below. According to a certain embodiment, the first and second sections each comprise a first end, the first end of the first section being interlockable with the first end of the second section. According to a certain embodiment, the assembly of said two first ends is carried out by gluing. This assembly method may be preceded by the fitting together of the ends of the first and second sections, depending on whether the first ends are fit-together or not. Gluing is a quick and easy process. Furthermore, the melting of the glue during the high-temperature compression process allows the two sections to be separated. All that remains is to remove the section in the upper position. Advantageously, the assembly of said two first ends is carried out using a quick-setting glue, preferably a cyanoacrylate glue. In the case where the ends of the first and second sections are interlocking, the assembly of said first two ends can be carried out using a force-fit assembly. Force mounting is a simple and quick operation to carry out which does not require additional fixing means. According to another embodiment, said two first ends are configured to allow a bayonet-type assembly. This type of assembly remains simple and quick without requiring a special assembly station. According to yet another embodiment, said two first ends are configured to allow assembly by screwing. This type of assembly is also simple and quick without requiring a workstation. special assembly.

[0033] According to yet another embodiment, said two first ends are held together by means of an elastic sleeve extending over a length allowing the two sections to be kept aligned.

[0034] Preferably, the rod is made of ceramic, so as to guarantee electrical insulation and resistance to high temperatures.

[0035] The invention also relates to a method for manufacturing a solid oxide electrochemical system, comprising a stack of a plurality of unit devices, each device comprising at least one interconnector, a solid oxide electrochemical cell and a spacer interposed between said interconnector and an interconnector of an adjacent device, each interconnector and each spacer having at least one perforation, preferably at least two perforations, allowing the passage of said associated guide rod, in order to maintain the stack in a predefined position, characterized in that said method comprises: - A step of providing a plurality of interconnectors, preferably pre-assembled to their solid oxide electrochemical cell, and a plurality of spacers, - A step of providing at least one, preferably at least two guide rods consisting of a first and a second section which can be assembled reversibly in accordance with the invention, - A step of removing sealing gaskets on the plurality of interconnectors and / or on the plurality of spacers, - A step of alternately stacking the plurality of interconnectors and spacers, so as to obtain a stack of a plurality of unitary devices according to a predefined position and in which the at least one, preferably the at least two guide rods, consisting of a first and a second assembled sections, pass through the perforations of the interconnectors and the spacers.

[0036] Various embodiments of the invention are provided, integrating according to all of their possible combinations the different optional characteristics set out below.

[0037] Advantageously, the manufacturing method further comprises: - A high-temperature compression step of the stack of unit devices, - A step of separating said first and second sections, so as to keep only the second section in the compressed stack.

[0038] Preferably, according to the configuration in which the electrochemical system at solid oxide comprises an upper plate and a lower plate framing the stack of the plurality of unit devices, the second section has a length Ht2 strictly less than the height Hs2 of the assembly constituted by the upper plate, the lower plate and the compressed stack.

[0039] Equally advantageously, the first section has a length Htl such that Htl + Ht2 is strictly greater than the height Hsl of the assembly constituted by the upper plate, the lower plate and the stack before compression. Brief description of the FIGURES

[0040] The invention will be better understood on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which: - [Fig.l] is a schematic perspective representation of a non-limiting example of a guide rod for the manufacture of a solid oxide electrochemical system. - [Fig.2] is a schematic front representation of a non-limiting example of a guide rod inserted into a solid oxide electrochemical system before compression for the left part of the figure and after compression for the right part of the figure. - [Fig. 3] is an exploded schematic perspective view of a non-limiting exemplary embodiment of a solid oxide electrochemical system according to one embodiment of the invention. - [Fig.4] is a schematic perspective representation of a non-limiting exemplary embodiment of a solid oxide electrochemical system according to an embodiment of the invention and after compression. - [Fig.5] is a schematic perspective representation of a non-limiting example of a detail of a solid oxide electrochemical system.

[0041] It is understood that the embodiments which will be described below are in no way limiting. In particular, it will be possible to imagine variants of the invention comprising only a selection of characteristics described below isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art. This selection comprises at least one preferably functional characteristic without structural details, or with only a part of the structural details if it is this part which is only sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art.

[0042] In particular, all the variants and all the embodiments described can be combined with each other if nothing prevents this combination from a technical point of view.

[0043] In the figures and in the remainder of the description, the elements common to several figures retain the same reference. Detailed description of the FIGURES

[0044] [Fig.l] is a schematic representation of a non-limiting exemplary embodiment of a guide rod configured for an electrochemical system according to the invention.

[0045] The guide rod 200 consists of an assembly of a first section 210 and a second section 220.

[0046] According to the principle of the invention, the assembly is reversible so as to allow the separation of said sections at the end of the compression step.

[0047] “Reversible” means that the two sections can be joined, then separated, then joined again to restore the integrity of the rod.

[0048] The guide rod is configured to pass through perforations provided in the stack of unit devices, and remain, at least as far as the lower section is concerned, in the electrochemical system. It therefore has electrically insulating properties and high temperature resistance properties.

[0049] "High temperature resistant" means that the rod can withstand temperatures of around 900°C.

[0050] The rod may be, for example, made of ceramic or steel coated with a layer of ceramic.

[0051] According to a first embodiment, the first 210 and the second 220 sections each comprise a first end 211, 221, the first end 211 of the first section being able to fit together with the first end 221 of the second section.

[0052] This embodiment is advantageous insofar as the interlocking promotes the alignment of the two rod sections. Good alignment is indeed important in order to prevent an element of the stack from catching when passing through the transition between the two sections.

[0053] It is understood that the first ends 211, 221 have a complementary shape allowing said ends to fit together.

[0054] This complementarity of shape can be obtained by making a bore at one of the first ends and by machining the complementary shape on the other of the first ends.

[0055] The assembly of said two first ends can also be carried out by gluing, whether the first ends are interlocking or not.

[0056] Gluing in addition to the interlocking of the first ends constitutes an advantageous assembly method since the contact surfaces between the two sections, and therefore the surfaces covered with glue, are larger.

[0057] Preferably, a quick-setting glue can be used, preferably a cyanoacrylate glue.

[0058] According to a variant, the interlocking of said two first ends can be carried out using a force-fit assembly.

[0059] For this purpose, a bore with a conical profile can be provided in one of the first ends and the machining of an equally conical profile on the other of the first ends.

[0060] According to another embodiment, the first end 211 of the first section and the first end 221 of the second section are machined to allow a bayonet-type assembly.

[0061] According to yet another embodiment, the first end 211 of the first section and the first end 221 of the second section are threaded to allow assembly by screwing.

[0062] According to yet another embodiment, the first end 211 of the first section and the first end 221 of the second section are held together by means of an elastic sleeve.

[0063] This sleeve may be made of an elastomer and may extend over a length allowing the two sections to be kept aligned.

[0064] As shown in [Fig.2] and 3, an electrochemical system comprises a stack 130 of a plurality of unit devices 170, the stack being framed by a lower plate 120 and an upper plate 110.

[0065] Each unit device 170, also called SRU for “Single Repetitive Unit” comprises at least one interconnector 150, a solid oxide electrochemical cell 160 and a spacer 140 interposed between said interconnector and an interconnector of an adjacent unit device.

[0066] Each interconnector and each spacer respectively has at least one perforation 152, 142, preferably at least two perforations, allowing the passage of an associated guide rod 200, in order to maintain the stack in a predefined position.

[0067] The interconnectors and spacers are generally square in shape and have two perforations arranged at two opposite vertices. This arrangement makes it possible to maintain the stack while minimizing the number of perforations to be machined.

[0068] In more detail, [Fig.5] represents a non-limiting example of an electrochemical device according to a sectional view.

[0069] The electrochemical device may for example be an electrochemical device for a solid oxide electrolyser, SOE, or for an oxide fuel cell. solid, SOFC, or for any other electrochemical system such as an electrolyzer or fuel cell.

[0070] The electrochemical device is mainly composed of a unit device 170 and the interconnector 150 of an adjacent unit device.

[0071] The electrochemical device therefore comprises an interconnector 150, designed to cooperate with a second interconnector 150, of another unitary device, similar or identical.

[0072] The electrochemical device further comprises an electrochemical cell 160 disposed between the interconnectors 150.

[0073] Each interconnector 150 is electrically conductive to supply the electrochemical cell 160 with electric current, for example in the case of an electrolyzer, or to capture an electric current generated at the level of the electrochemical cell 160, for example in the case of a fuel cell.

[0074] The electrochemical cell 160 may be any type of electrochemical cell, in particular an electrochemical cell carrying out a redox reaction of compounds present in a gas stream supplied to said electrochemical cell 160. For example, the electrochemical cell may be a cell of a solid oxide electrolyzer for decomposing water vapor molecules and producing a hydrogen-rich gas stream. For example, the electrochemical cell may be a cell of a solid oxide fuel cell for oxidizing hydrogen molecules with oxygen molecules to produce an electric current.

[0075] The electrochemical cell 160 may have any type of architecture. For example, the electrochemical cell may be composed of several layers of materials, one of these layers providing, among other things, a mechanical support function.

[0076] Optionally, the electrochemical device may comprise an electrical contact layer (not shown) between the electrochemical cell 160 and one of the interconnectors 150. Such an electrical contact layer may be made by a grid of an electrically conductive material, such as nickel, allowing the passage of the gas flow while ensuring electrical contact between the interconnector and the electrochemical cell.

[0077] Optionally, the electrochemical device may comprise an electrical contact layer (not shown) between the electrochemical cell 106 and the other of the interconnectors 150. Such an electrical contact layer may be produced in any possible form, for example in the form of an LSM (for “lanthanum strontium manganite”) layer comprising gas circulation channels, thus allowing the passage of the gas flow while ensuring electrical contact between the interconnector and the electrochemical cell.

[0078] The electrochemical device further comprises a spacer 140 disposed between the interconnectors 150. This spacer 140 has the role of providing electrical insulation between the interconnectors 150 so as not to electrically short-circuit the electrochemical cell 160. Generally, this spacer 140 is made of a mica-based material, which is an electrical insulator at the operating temperature of the electrochemical device, this temperature being able for example to reach 600°C-850°C, or even higher temperatures, for example in the case of a solid oxide electrolyser.

[0079] In the example shown, the gas flow(s) is(are) supplied to the electrochemical cell by an inlet channel 180, and recovered from the electrochemical cell, by an outlet channel 190, each of the channels 180 and 190 passing through the interconnectors 150 and the spacer 140. One of the interconnectors 150 comprises a passage, for example formed by channels provided in the thickness of said interconnector, allowing the gas flow to pass from the channel 180 to the electrochemical cell 160. The other of the interconnectors also comprises a passage, for example formed by channels provided in the thickness of said interconnector, allowing the gas flow coming from the electrochemical cell 160 to be evacuated to the channel 190. According to an exemplary embodiment, the passage provided in one of the interconnectors for the gas flow is arranged in a direction perpendicular to that of the passage provided in the other of the interconnectors.In the example shown, the circulation of the gas flow is indicated by dotted arrows.

[0080] The spacer made of a mica-based material, or a similar material, which is not gas-tight. Thus, multiple seals 300 are provided in the electrochemical device to provide gas-tightness between the interconnectors 150 and the electrochemical cell 160, so as to channel the gas flow(s) and direct the gas flow entering the electrochemical device to the electrochemical cell 160, and collect the gas flow coming from the electrochemical cell for evacuation from the electrochemical device. These seals 300 are generally made of sintered glass.

[0081] The method for manufacturing a solid oxide electrochemical system 100 comprising a rod according to the invention will now be described.

[0082] According to a first step, a plurality of interconnectors 150 are provided, preferably each pre-assembled to a solid oxide electrochemical cell 160, as well as a plurality of spacers 140.

[0083] According to a second step, at least one, preferably at least two guide rods 200 in accordance with the invention are provided.

[0084] According to a third step, sealing gaskets 300 are deposited on the plurality of interconnectors and / or on the plurality of spacers.

[0085] These seals can be in the form of slip beads, deposited for example by means of a robotic operation.

[0086] The slip is classically a suspension, for example of aqueous base or of an organic solvent, containing: - ceramic or glass particles; and - optionally dispersants, plasticizers, lubricants, and / or binders, preferably temporary.

[0087] According to a fourth step, the plurality of interconnectors and spacers are stacked alternately, so as to obtain a stack 130 of a plurality of unitary devices 170 according to a predefined position and in which the at least one, preferably the at least two guide rods pass through the respective perforations 152, 142 of the interconnectors and the spacers.

[0088] Concretely, the lower plate 120 is first positioned on a plane and at least one, preferably at least two, guide rods are fixed.

[0089] Then the first interconnector pre-assembled to an electrochemical cell and on which a sealing bead has been deposited is pressed against the lower plate. This is followed by an alternation of spacer 140 and interconnectors 150.

[0090] After stacking the so-called closing interconnector, the plate is positioned on upper 110.

[0091] During stacking, temporary steel rods may be used whose diameter is adjusted to the diameter of the perforations 152, 142 of the interconnectors and the spacers, then these temporary rods may be replaced by the ceramic rods 200 of a slightly smaller diameter at the end of stacking.

[0092] As shown in the left part of [Fig.2], we obtain the electrochemical system which has a height Hsl.

[0093] In order to improve the electrical conductivity and reduce the contact resistance between the electrochemical cells, and also to seal the system, the method further comprises a step of high-temperature compression of the stack 130 of the unit devices.

[0094] This step leads to the evaporation of the binders, solvents and other liquids present in the slip and allows the vitrification of the sealing beads 300. This results in a spreading of the sealing joints 300, and consequently a collapse of the stack 130.

[0095] As shown in the right part of [Fig.2], the compressed electrochemical system then has a height Hs2 lower than Hsl.

[0096] In order to keep the electrochemical system compressed, the electrochemical system is locked in this position by means of fasteners. The upper plate 110 and the lower plate 120 have for this purpose passages 111, 121 respectively for screw / nut type fixing means.

[0097] The locking ensures a compression of the order of 4000 N which guarantees the sealing of the system.

[0098] Finally, a step of separating said first and second sections is carried out, so that only the second section remains in the compressed stack.

[0099] As shown in [Fig.2], the second section has a length Ht2 strictly less than the height Hs2 of the assembly consisting of the upper plate, the lower plate and the compressed stack.

[0100] Preferably, the first end 221 of the second section 220 is located inside the upper plate 110 while the second end 222 of the second section 220 is located inside the lower plate 120.

[0101] The first section 210 has a length Htl such that Htl + Ht2 is strictly greater than the height Hsl of the assembly constituted by the upper plate, the lower plate and the stack before compression.

[0102] In other words, the second end 212 of the first section 210 opens out of the upper plate 110.

[0103] This allows for a rod to pass through the stack before compression.

[0104] The first section 210 can be removed either by removing the rod 200 and disassembling the two sections 210, 220, then reintroducing the second section into the stack, or by disassembling the two sections 210, 220 within the stack 130.

[0105] It is also possible to provide means for anchoring the second end 222 of the second section 220 in the lower plate 120, in order to be able to unscrew the first section 210 in the case of an assembly by screwing or of the bayonet type.

[0106] In the case of assembly by gluing, the high temperature compression step melts the glue, which allows the first section to be removed directly.

[0107] Once the electrochemical system is locked, it is possible to place it under an electro-reducing atmosphere to activate the electrochemical cells.

[0108] Then, we can carry out various leak-tightness tests, voltage and current measurements of the electrochemical system.

[0109] Once removed, the first section 210 can be used for the manufacture of another electrochemical system. It is then assembled to a section similar to the second section 220.

[0110] The use of a rod composed of two removable sections according to the invention thus makes it possible to avoid having to saw the rod and to recycle the waste at the end of the manufacture of the electrochemical system.

[0111] Of course, the invention is not limited to the examples which have just been described.

Claims

Claims

1. Guide rod (200) for manufacturing a solid oxide electrochemical system (100), said electrochemical system comprising a stack (130) of unit devices (170), each device comprising at least one interconnector (150), a solid oxide electrochemical cell (160) and a spacer (140) interposed between said interconnector and an interconnector of an adjacent device, each interconnector and each spacer having at least one perforation (152, 142), preferably at least two perforations, allowing the passage of said associated guide rod, in order to maintain the stack in a predefined position, said manufacturing comprising a step of compressing the stack (130), characterized in that: - said guide rod consists of an assembly of a first (210) and a second (220) sections,said assembly being reversible so as to allow the separation of said sections at the end of the compression step, - said guide rod is electrically insulating and resistant to high temperatures.,

2. Guide rod according to claim 1, characterized in that the first (210) and the second (220) sections each comprise a first end (211, 221), the first end (211) of the first section being able to fit together with the first end (221) of the second section.

3. Guide rod according to any one of the preceding claims, characterized in that the assembly of said two first ends is carried out by gluing.

4. Guide rod according to any one of the preceding claims, characterized in that the assembly of said two first ends is carried out by means of a quick-setting glue, preferably a cyanoacrylate glue.

5. Guide rod according to claim 2, characterized in that the fitting of said two first ends is carried out by force-fitting.

6. Guide rod according to claim 1, characterized in that the first (210) and second (220) sections each comprise a first end (211, 221), the first end (211) of the first section and the first end (221) of the second section being configured to allow a bayonet-type assembly.

7. Guide rod according to claim 1, characterized in that the first (210) and the second (220) sections each comprise a first end (211, 221), the first end (211) of the first section and the first end (221) of the second section being configured to allow assembly by screwing.

8. Guide rod according to claim 1, characterized in that the first (210) and the second (220) sections each comprise a first end (211, 221), the first end (211) of the first section and the first end (221) of the second section being held together by means of an elastic sleeve extending over a length allowing the two sections to be kept aligned.

9. Guide rod according to any one of the preceding claims, characterized in that said rod is made of ceramic.

10. A method of manufacturing a solid oxide electrochemical system (100), comprising a stack (130) of a plurality of unit devices (170), each device comprising at least one interconnector (150), a solid oxide electrochemical cell (160) and a spacer (140) interposed between said interconnector and an interconnector of an adjacent device, each interconnector and each spacer having at least one perforation (152, 142), preferably at least two perforations, allowing the passage of said associated guide rod, in order to maintain the stack in a predefined position, characterized in that said method comprises: - A step of providing a plurality of interconnectors (150) preassembled to their solid oxide electrochemical cell (160), and a plurality of spacers, - A step of providing at least one,preferably at least two guide rods (200) according to any one of claims 1 to 9, - A step of depositing seals (300) on the plurality of interconnectors and / or on the plurality of spacers, - A step of alternately stacking the plurality of interconnectors and spacers, so as to obtain a, stacking (130) of a plurality of unitary devices (170) according to a predefined position and in which the at least one, preferably the at least two guide rods pass through the perforations (152, 142) of the interconnectors and the spacers.

11. Method for manufacturing a solid oxide electrochemical system, according to the preceding claim, characterized in that the method further comprises: - A step of compressing at high temperature the stack of unit devices, - A step of separating said first and second sections, so that only the second section remains in the compressed stack.

12. Method for manufacturing a solid oxide electrochemical system, according to the preceding claim and in which the solid oxide electrochemical system (100) comprises an upper plate (110) and a lower plate (120) framing the stack (130) of the plurality of unitary devices (170), characterized in that the second section has a length Ht2 strictly less than the height Hs2 of the assembly constituted by the upper plate, the lower plate and the compressed stack.

13. Method for manufacturing a solid oxide electrochemical system, according to the preceding claim, characterized in that the first section has a length Htl such that Htl + Ht2 is strictly greater than the height Hsl of the assembly constituted by the upper plate, the lower plate and the stack before compression.