Electrolysis assembly

Abstract

The invention relates to an electrolysis assembly comprising at least one housing with an interior and at least one stack assembly in the interior of the housing. The stack assembly comprises a plurality of electrolysis cells stacked in a stacking direction, and at least some of the electrolysis cells comprise a respective membrane electrode assembly and a respective interconnector, wherein the membrane electrode assembly and the interconnector each have an oxygen side and a hydrogen side, and at least some of the electrolysis cells have contact elements between the membrane electrode assembly and the interconnector, said contact elements being designed to be viscous in an operating state of the electrolysis assembly and solid in a rest state of the electrolysis assembly.

Description

[0001] DESCRIPTION

[0002] Electrolysis arrangement

[0003] The invention relates to an electrolysis arrangement which can be used in electrolysis plants such as high-temperature electrolysis plants or fuel cell plants.

[0004] The electrolysis arrangement according to the invention is particularly suitable for use in solid oxide electrolysis cell systems (SOEC) and in reversible solid oxide cell systems (rSOC) in electrolysis mode. Such systems are primarily used for high-temperature electrolysis (HTE).

[0005] A solid oxide electrolyzer (SOEC) comprises at least one electrolysis cell that uses electrical energy to split water (H2O) into its components, hydrogen (H2) and oxygen (O2). The structure and function of a solid oxide electrolysis cell are similar to those of a solid oxide fuel cell (SOFC), as they are based on the same technology. A key difference is that electrolysis uses water vapor (H2O(g)) as the input medium (reactant gas), whereas a fuel cell uses oxygen and fuel gas (e.g., hydrogen) as the input media.

[0006] A solid oxide electrolyzer utilizes high-temperature operation (typically 650-1000°C) because its efficiency is significantly higher than that of other electrolysis technologies. This technology takes advantage of the fact that at these temperatures, the ceramic materials used in the electrolytes become ionically conductive. A solid oxide electrolyzer consists of several components, each performing a different function. The essential components of a solid oxide electrolyzer include a stack with numerous cells, each cell comprising, among other components, an anode, an electrolyte layer, and a cathode. The cathode often contains a mixture of nickel and electrolyte materials. Water, in the form of steam in high-temperature electrolysis, is fed to the cathode.The electrolysis process works as follows: when an electrical voltage is applied to the cell that is above the open-circuit voltage (OCV), the water diffuses into the cathode, where the electrochemical conversion (redox reaction) of the water vapor takes place by absorbing electrons, producing hydrogen and oxygen ions. The electrolyte layer consists of a solid electrolyte material, such as yttrium-stabilized zirconia (YSZ). This electrolyte layer enables the transport of oxygen ions (O). 2 ) from the cathode to the anode. The anode consists of anode materials such as lanthanum manganese cobaltite or lanthanum ferrite. At the anode, the oxygen ions (O 2 ) molecular oxygen (O2) is produced by releasing electrons.

[0007] Solid oxide electrolysis cells are efficient due to their high operating temperatures and can produce clean hydrogen. They are used in hydrogen production, energy storage, and other industrial processes.

[0008] High-temperature electrolysis (HTE) is an electrolysis process for producing hydrogen from water at high temperatures using electrical energy. In contrast to low-temperature electrolysis (LTE), which operates at temperatures below 100 degrees Celsius, high-temperature electrolysis takes place at much higher temperatures, typically in the range of 500 to 1000 degrees Celsius. In low-temperature electrolysis, a polymer electrolyte membrane (PEM) is usually used as the electrolyte and is therefore often referred to as a PEM electrolysis process. The PEM is a thin polymer membrane that allows protons to pass through while blocking electrons and gases. A perfluorosulfonated polymer, such as Nafion, is often used as the material for the PEM. PEM electrolysis is frequently used in applications where fast response time and flexibility are required.These include, for example, hydrogen production for fuel cell vehicles, the integration of renewable energies through electrolysis and decentralized hydrogen production.

[0009] In a generic electrolysis arrangement, several, often a large number, of membrane electrode assemblies (MEAs) are arranged in a stack. Such stacks are also called electrolysis cell stacks or fuel cell stacks. Such stacks generally have a large number of levels, with each MEA of a stack being considered a single level. Interconnectors (also known as bipolar plates) are arranged between these levels. In a stack, a large number of these MEAs and interconnectors are stacked as repeating units. The finished stack is also referred to as a stack. Such stacks can have several hundred levels, in particular more than 800 or more than 900 levels.

[0010] For the electrolysis process, gas streams are fed into and removed from the MEA. The supplied gas is typically guided through channels arranged on the surface of the MEA.

[0011] EP 3360187 A1 discloses a system for regulating the pressure of a reactor for high-temperature electrolysis or co-electrolysis (HTE) or for a pressurized SOFC fuel cell stack. The operation of the system includes: regulating the volume flow of a moisture-containing gas upstream of one of the chambers to ensure electrochemical stability at a preset operating point; and pressure control using valves located downstream of the stack to regulate gases, including the moisture-containing gas, which are generally hot.

[0012] From US 2008118803 A1 a fuel cell unit is known, consisting of an electrolyte with an anode on one side and a cathode on the other side, each provided with a flow / gas distribution grid with gas supply / discharge, wherein each grid is adjacent to a separator plate and a seal acting on the separator plate.

[0013] Research into conventional electrolysis systems has shown that the structural designs of known systems leave room for optimizing electrolysis with high efficiency during continuous operation.

[0014] The object of the present invention is to provide an electrolysis system that enables high efficiency even during continuous operation. This object is achieved by the electrolysis system specified in the claims. Advantageous embodiments are the subject of the subclaims.

[0015] According to the invention, an electrolysis arrangement comprises at least one housing with an interior space, and at least one stack arrangement arranged in the interior space of the housing, wherein the stack arrangement comprises a plurality of electrolysis cells stacked in a stacking direction, wherein at least some of the electrolysis cells each comprise a membrane electrode assembly (MEA) and an interconnector, and wherein the membrane electrode assembly and the interconnector each have an oxygen side and a hydrogen side. The electrolysis arrangement is characterized in that at least some electrolysis cells have support elements between the membrane electrode assembly and the interconnector, and wherein the support elements are designed and configured such that they are viscous in an operating state of the electrolysis arrangement and solid in a rest state of the electrolysis arrangement.

[0016] The support elements according to the invention primarily serve to adjust and fix the MEA relative to the interconnector. A load flow pointing in the stacking direction of the stack arrangement due to tension between the components of the stack arrangement can also be at least partially compensated by the support elements, thus reducing the risk of damage to the MEA. These tension states within the stack arrangement are, for example, the result of different material expansion of the components of the stack arrangement during temperature changes due to different thermal expansion coefficients.

[0017] The support elements are preferably separate elements that are placed between the MEA and the interconnectors to create the stack arrangement. The material of the support elements is selected so that they are viscous when the electrolysis arrangement is in operation. This ensures good contact between the support elements on the MEA on the one hand and on the interconnector on the other. The support elements are preferably arranged between the oxygen sides of the MEA and the interconnector. The transition between a viscous state and a solid state of the support elements occurs, for example, at the glass transition temperature. When the electrolysis arrangement is in operation, the support elements assume a temperature of over 900°C, in particular 950°C. When the electrolysis arrangement is in the idle state, the electrolysis process is stopped and the temperature of the arrangement is below the glass transition temperature of the support elements.

[0018] A design with support elements with a height of approximately 200 to 400 pm has proven technically successful. The support elements are preferably made of glass or glass ceramic.

[0019] In a preferred variant, the interconnector of a stack arrangement according to the invention is a flat metal component. The component can be made, for example, of the material known under the designation Crofer 22, such as the materials 1.4760 XlCrTiLa22 or 1.4755 - XlCrWNbTiLa22-2. For rapid and cost-effective production of a large number of interconnectors, the interconnector can be a punched sheet. In principle, it is conceivable that the shape of the plate-shaped interconnectors can be freely selected, i.e., in particular, round, circular, oval, square, triangular, or the like. However, it has been shown that the production of a stack arrangement according to the invention is facilitated when the interconnectors are rectangular. The plate-shaped interconnector can thus be stacked quickly and easily orientated.

[0020] The interconnector and the membrane-electrode assembly are plate-shaped elements whose flat surfaces each define a hydrogen and oxygen side. Within the stack arrangement, the hydrogen sides of directly adjacent membrane-electrode assemblies and interconnectors face each other. Likewise, the oxygen sides of directly adjacent membrane-electrode assemblies and interconnectors face each other, as do the hydrogen sides. During electrolysis, oxygen is produced on the oxygen side of the membrane-electrode assembly, which is transported away through the space formed between the oxygen side of the membrane-electrode assembly and the oxygen side of the interconnector.A reactant gas, in this case water vapor, which is conducted between the hydrogen side of a membrane electrode assembly and an interconnector, is converted into product gas, in this case hydrogen, during electrolysis on the hydrogen side of the membrane electrode assembly.

[0021] The space between the oxygen sides of the interconnectors and membrane electrode assemblies is fluidically separated from the space between the hydrogen sides of the interconnectors and membrane electrode assemblies to prevent mixing of hydrogen and oxygen. For this purpose, seals are planned to be provided on the hydrogen side and the oxygen side between the interconnectors and the membrane electrode assemblies.

[0022] In a preferred embodiment, it is contemplated that on the oxygen side of at least some membrane electrode assemblies there is at least one layer which has recesses for receiving the support elements, and wherein the layer having the recesses is preferably an oxygen-permeable structure by means of which oxygen released on the oxygen side of the membrane electrode assembly can be diverted to a side edge of the membrane electrode assembly.

[0023] The oxygen-permeable structure on the oxygen side of the membrane-electrode assembly serves to dissipate oxygen generated on the oxygen side of the membrane-electrode assembly into the interior of the housing. For this purpose, according to a preferred embodiment, the oxygen-permeable structure is designed to be open in the region of at least one side surface of the stack assembly to dissipate the oxygen into the interior of the housing. It is conceivable that the oxygen-permeable structure is designed as a channel structure, preferably a channel structure oriented substantially perpendicular to the direction of a reactant gas channel structure. The channels can, in particular, be designed as ribs.The channels can be limited laterally by channel bridges, downwards by the body of the MEA and upwards the channels can be open so that oxygen generated between the MEA and the interconnector arranged above it can be discharged in a directed manner.

[0024] Oxygen can also be conducted into the interior if the oxygen-conducting structure is designed as a gas-permeable material, for example, as a porous ceramic or the like. In particular, the oxygen-conducting structure can be a layer or one or more coatings of the membrane-electrode assembly. Oxygen transport can be achieved, in particular, by means of a pressure gradient between the interior of the housing of the electrode assembly and the gas-conducting space between the oxygen sides of two membrane-electrode assemblies and interconnectors arranged directly above one another.

[0025] According to one embodiment, the support elements and / or the recesses have a contour shape selected from the group consisting of circular, circular segment-shaped, square, rectangular, quadrangular, triangular, or diamond-shaped. The contour shapes of the support elements, i.e., the outer contour of the support elements in a plane parallel to the plane of the MEA, do not have to be identical to the contour of the recesses. Preferably, the support elements are arranged between the oxygen sides of the MEA and the interconnector. It must be ensured that oxygen can be discharged laterally between the oxygen sides of the MEA and the interconnector.

[0026] A design that has proven technically successful is one in which the surface area of ​​the projection area of ​​a support element is approximately 5-15% of the surface area of ​​the membrane electrode assemblies of the electrolysis cell that can be exposed to reactant gas. The projection area of ​​a support element is defined as the area projected by orthogonal projection into the plane of the membrane electrode assemblies or the interconnector of the electrolysis cell.

[0027] Preferably, the surface area of ​​the projection surface of the support elements can be smaller than the surface area of ​​the recesses for accommodating the support elements. This allows for the creation of free space around the support surfaces between the oxygen sides of the MEA and the interconnector, even when support elements are closely arranged in the edge area of ​​the MEA, which serves to dissipate oxygen.

[0028] For the design of the interconnectors, a first variant envisions at least some interconnectors being formed as flat, particularly plate-shaped components that are free of gas-conducting structures on the hydrogen side and / or on the oxygen side. These interconnectors are preferably designed as flat steel sheets. The interconnectors may have coatings that, however, do not have a gas-conducting function. For example, an oxygen-impermeable coating may be arranged on the oxygen side of the interconnectors, preventing oxygen from passing through to the metallic material of the interconnector in order to reduce or prevent oxidation of the metallic material.

[0029] The interconnectors preferably each have two manifold openings, by means of which a reactant gas manifold structure and a product gas manifold structure are formed within the stack arrangement. The manifold openings of the interconnectors that delimit the manifold structures within the stack arrangement are preferably completely open, i.e., are formed without webs within their outer opening edge. Each interconnector preferably has exactly one manifold opening for forming the reactant gas manifold structure and exactly one manifold opening for forming the product gas manifold structure.

[0030] According to one embodiment, at least some of the electrolysis cells may comprise a mesh-like metal mesh, preferably comprising nickel, in particular an iron-nickel alloy, arranged between the membrane electrode assembly and the interconnector. The ratio of iron to nickel in the metal mesh may, for example, be 50:50. The use of an iron-chromium alloy, preferably the material known as Crofer 22, for example, material 1.4760 XlCrTiLa22 or 1.4755 - XlCrWNbTiLa22-2, is also conceivable.

[0031] The production of a stack arrangement can be facilitated by at least some components of the stack arrangement, such as membrane electrode assemblies, interconnectors, connector plates, top plate and / or base plate, each having an orientation feature by means of which the components can be oriented in the stack assembly for producing the stack arrangement, in particular according to the poka-yoke principle. In particular, with an orientation feature on the interconnectors, these can advantageously be oriented and arranged manually, mechanically or with machine support, in particular using the poka-yoke principle, in order to produce the stack assembly of the stack arrangement in such a way that a specific alignment pattern is achieved within the stack arrangement. The orientation features facilitate the detection of the orientation of the components in order to reduce or completely avoid errors.

[0032] In particular, it can be provided that at least some interconnectors in the stack arrangement are stacked alternately rotated by 180° based on orientation features arranged on the interconnectors. The 180° rotation can occur about the axis running in the stacking direction. This rotation can be performed, for example, in order to arrange the interconnectors in the stacked assembly of the stack arrangement on one side at one edge or mirror-symmetrically at two opposite edges with alternating placement. For example, contact devices for connecting electrical connector bodies can be placed alternately in the stack arrangement in such a way that they are more easily accessible for later contacting, for example, to test the functionality of the stack arrangement after joining.

[0033] For an enclosure of the stack arrangement that allows the application of high compressive forces to the stack composite of the stack arrangement, it is intended that the stack arrangement has a top plate that limits the stack arrangement upwards in the stacking direction and a base plate that limits the stack arrangement downwards in the stacking direction.

[0034] According to one embodiment, the transition between a base plate and the first electrolysis cell of the stack arrangement in the stacking direction, or between the last electrolysis cell in the stacking direction and a top plate of the stack arrangement, is envisaged for a connector plate to be arranged between the top plate and the last membrane-electrode arrangement in the stacking direction, arranged below the top plate, and / or for a connector plate to be arranged between the base plate and the first membrane-electrode arrangement in the stacking direction, arranged above the base plate. According to a preferred embodiment, the connector plate is designed as a plate-shaped sheet, wherein the outer contour of the connector plate corresponds at least substantially to the contour of the interconnector arranged adjacent to the connector plate in the stacking direction, and wherein the connector plate is preferably free of gas-conducting structures.

[0035] Such a connector plate, which preferably has a contour shape corresponding to the interconnectors, can fulfill various functions. On the one hand, the connector plate can establish an electrically conductive connection between the base plate or top plate and the first or last electrolysis cell. Furthermore, the connector plate can be designed and configured to absorb and compensate for mechanical stresses in the stack arrangement, particularly those directed in the stacking direction. This can reduce the risk of stress cracks in the electrolysis cells of the stack arrangement and in particular in the membrane-electrode assemblies of the electrolysis cells. In particular, the connector plate can serve to compensate for unevenness of the electrolysis cells arranged one above the other, which can reduce electrical contact with the top or base plate.These unevennesses can arise, for example, from joining the stack during assembly. Due to its flexibility, the connector plate establishes a flat contact with the stack of electrolysis cells compared to the top or bottom plate, with the connector plate, in turn, being in electrical contact with the top or bottom plate.

[0036] A connector plate arranged between the base plate and the first electrolysis cell above the base plate in the stacking direction preferably has manifold openings if it covers the reactant gas opening or the product gas opening of the base plate. In principle, the connector plate can have the same external dimensions, in particular the same thickness dimensions, as an interconnector. However, it can also be thicker or thinner than the interconnector. Interconnectors and connector plates are preferably made of the same material. A connector plate is preferably electrically conductive, such that an electrical contact is established between the connector plate and the base plate or top plate. The connector plate can serve, among other things, to compensate for different mechanical compressive forces across the cross-sectional area of ​​the stack arrangement, seen perpendicular to the stacking direction.For example, due to an MEA positioned approximately centrally to an interconnector, higher compressive forces may occur in the center of the stack arrangement than in the edge region of the stack arrangement. Accordingly, the connector plate may be designed to be thicker in its edge region than in its center region.

[0037] According to one embodiment, it is provided that the connector plate, and / or the top plate and / or the base plate has a coating, wherein the coating comprises a semiconducting oxide ceramic, in particular a ceramic comprising lanthanum (La), strontium (Sr), manganese (Mn) and / or cobalt (Co), preferably lanthanum-strontium-manganese-cobalt (LSMC), manganese cobalt iron oxide (MCF), lanthanum strontium manganese (LSM), lanthanum-strontium-cobalt-iron oxide (LSCF) or lanthanum-manganese-cobalt (LMC).

[0038] With regard to the coating of the connector plate, it is envisaged that the connector plate has a coating on at least one side, at least in some areas, in particular such that several spaced-apart surface areas of the connector plate are coated, preferably in the form of a checkerboard pattern. The free areas between the coating zones can help to allow a high binder content in the coating to escape during the curing of the layer, for example, in a joining process during the production of the stack arrangement. Without sufficient opportunity for the binder content to escape, for example via the free areas between the coating zones, pore formation or undesirable height differences on the connector plate can occur after the coating has cured.

[0039] To support a joining process during the manufacture of the stack arrangement according to the invention and to maintain a clamping force between the base plate and the top plate of the stack arrangement, it can be provided that the top plate and the base plate each have clamping devices, in particular in the form of holding elements projecting outwards at the edge region of the top plate and the base plate, such that clamping means can be arranged on the outside of the stack arrangement at a distance from the stack arrangement between the clamping devices of the top plate and the base plate, by means of which a tensile force acting between the top plate and the base plate along the stack direction axis can be applied.

[0040] The clamping devices can in particular be arranged such that the holding elements are aligned at the top and bottom in the stacking direction. This makes it easy to attach a clamping device running parallel to the stacking axis to the holding elements, with which a tensile force running parallel to the stacking direction axis can be applied between the top plate and the base plate. It is conceivable that the holding elements of the base plate and / or the top plate have holes for receiving or attaching clamping devices. The clamping device can be, for example, a rod(s) or a belt that is connected to the holding elements of the top plate and the base plate. When arranging clamping devices between the top plate and the base plate, care must be taken to ensure that the clamping devices do not create a potential equalization between the top plate and the base plate or with interconnectors arranged in the stack arrangement.The clamping devices should therefore be electrically insulated or non-conductive, at least in the contact area of ​​the clamping devices of the top plate and / or base plate.

[0041] For the electrical contacting of the top plate and / or the base plate, in particular for supplying the electrical energy required for the electrolysis process to the stack arrangement, it is envisaged that the top plate and / or the base plate have contact devices for electrically contacting the top plate and / or the base plate. In a particularly advantageous embodiment, the contact devices are formed by means of the clamping devices.

[0042] For electrical contacting of the interconnectors, for example for measuring the electrical potential of an electrolysis cell, it can be provided that at least some of the interconnectors have at least one contact device in their edge region, which is electrically conductively connected to the interconnector.

[0043] In principle, various designs are conceivable for the design of the contact devices of the interconnectors. Preferably, in any case, it is contemplated that the contact devices are configured and designed in such a way that, even in a closely stacked stack of the stack arrangement, measuring equipment can be easily inserted with little risk of electrical bridging of stacked interconnectors. According to a first variant, it can be provided that the contact device comprises a hole, in particular an elongated hole, machined into the edge region of the interconnector. With a hole or elongated hole, in particular through the interconnector as seen in the stacking direction, suitable measuring equipment can be connected to the interconnector quickly and easily, in particular with a force-fitting and / or form-fitting connection. The contact devices can protrude laterally outwards at the side edge of the stack arrangement to support easy contacting.Preferably, however, the contact devices can be arranged such that they are located within the side edge of the stacking arrangement. The side contour of the stacking arrangement between the top plate and the bottom plate is, for example, approximately rectangular in shape with four straight side edges when projected orthogonally onto a plane perpendicular to the stacking direction.

[0044] In order to enable rapid contacting and to reduce the risk of unwanted electrical bridging of interconnectors stacked on top of one another, it is contemplated that the interconnectors, each having at least one contact device, are designed and / or arranged within the stack arrangement in such a way that the contact devices of the interconnectors of two electrolysis cells stacked on top of one another are arranged offset from one another transversely to the stacking direction.

[0045] To further improve fast and reliable contacting of the interconnectors, the interconnectors can be provided with recesses in their edge areas, which are aligned in the stacking direction of the stack arrangement with the contact device of an interconnector arranged directly above and below. This places the contact device of an interconnector prominently above the contact devices of its immediate neighbors in the stack, supporting accurate contacting.

[0046] The following should be noted regarding the definition: In the context of this application, the term "interconnector" refers to both an interconnector and a bipolar plate. The statements regarding interconnectors contained in this application also apply accordingly to bipolar plates. High-temperature electrolysis, in the context of this application, refers to electrolysis in the temperature range between 600°C and 1000°C, in particular 800°C and 950°C. However, high-temperature analysis is not limited to this temperature range; it can also be carried out at higher temperatures, for example, up to 1400°C.

[0047] The present invention is explained in more detail with reference to the following drawings. They show:

[0048] Fig. 1 is a highly schematic representation of an inventive

[0049] Electrolysis arrangement,

[0050] Fig. 2 is a simplified exploded view of a preferred variant of

[0051] MEA, interconnectors and glass seals of an electrolysis arrangement according to the invention,

[0052] Fig. 3 is a simplified exploded view of a general structure of a

[0053] Stack arrangement of an electrolysis arrangement according to the invention,

[0054] Fig. 4a, 4b, 4c a simplified sectional view of a stack arrangement halved lengthwise with a tapered manifold structure,

[0055] Fig. 5 a simplified exploded view of stacked interconnectors,

[0056] Fig. 6a, 6b a detailed view of glass seals on an interconnector,

[0057] Fig. 7 a connector plate, and

[0058] Fig. 8 is a highly schematic sectional view of channel cross-sections on an interconnector.

[0059] Figure 1 shows a highly schematic representation of an electrolysis arrangement 10 according to the invention with a housing 12 and a stack arrangement 16 arranged in the interior 14 of the housing 12. The stack arrangement 16 comprises a plurality of electrolysis cells 18, which in the present example are enclosed in the stacking direction S at the bottom by a base plate 42 and at the top by a top plate 40. A reactant gas manifold structure 66 and a product gas manifold structure 68 are indicated by dashed lines. Within the reactant gas manifold structure 66, a reactant gas, such as water vapor (H2O(g)), is fed into the stack arrangement 16 and guided to the electrolysis cells 18. In the product gas manifold structure 68, a product gas, such as hydrogen (H2), is guided away from the electrolysis cells 18 and out of the stack arrangement 16.

[0060] Figure 2 shows an exploded view of a preferred variant of an electrolysis cell, consisting of a membrane electrode assembly (MEA) 20, an interconnector 22, a glass seal 46 arranged above the interconnector 22, and two glass seals 44 arranged below the interconnector 22. The plate-shaped MEA 20 has a hydrogen side (bottom side not shown) and an oxygen side (top side shown). The interconnector 22, which is also approximately plate-shaped, also has a hydrogen side (top side shown) and an oxygen side (bottom side not shown). The oxygen side of the interconnector 22 lies on the oxygen side of the MEA 20 when the electrolysis cell is assembled. To form a stack arrangement 16 (cf. Fig. 1 or Fig. 3), a plurality of electrolysis cells 18 are stacked one above the other in a stacking direction S.Accordingly, an MEA 20 is connected to the hydrogen side of the interconnector 22. The adjoining MEA 20 of an electrolysis cell 18 arranged immediately above in the stacking direction S lies with its hydrogen side on the hydrogen side of the interconnector 22 of the electrolysis cell 18 arranged directly below.

[0061] The interconnector 22 has two manifold openings 28, 30, a first manifold opening 28 serving for the conduction of reactant gas and a second manifold opening 30 serving for the conduction of product gas. On the oxygen side of the interconnector 22, two glass seals 44 are arranged around the opening edge of the manifold openings 28, 30. The glass seals 44 seal the manifold openings 28, 30 of two stacked electrolysis cells 18 in such a way that a reactant gas stream or the product gas stream is respectively guided through a reactant gas manifold structure 66 or product gas manifold structure 68 formed by the manifold openings 28, 30 of stacked electrolysis cells 18. The individual electrolysis cells 18 are furthermore designed such that a reactant gas flow guided in a reactant gas manifold structure 66 can be guided from there to the hydrogen side of the interconnector 22.On the hydrogen side of the interconnector 22, the reactant gas stream for the electrolysis process comes into contact with the hydrogen side of an MEA 20 located on the hydrogen side of the interconnector 22. During the electrolysis process, the reactant gas is converted into product gas between the hydrogen side of the interconnector 22 and the hydrogen side of the MEA 20. The resulting product gas is further conducted on the hydrogen side of the interconnector 22 into the manifold opening 30 of the interconnector 22, which is provided for the conduction of product gas.

[0062] To guide reactant gas from the manifold opening 28 of the interconnector 22, a reactant gas line structure 32 can be formed on the hydrogen side of the interconnector 22—as in the example shown. The channel structure on the interconnector 22 can have 60 to 100 channels to achieve a fine, laminar flow.

[0063] As also indicated in Fig. 2, an oxygen-permeable structure 34 designed as a channel structure can be formed on the oxygen side of the MEA 20 for guiding the oxygen generated there. The oxygen-permeable structure 34 can be designed and configured such that the oxygen is discharged in a lateral direction, transverse to the orientation of the reactant gas conduit structure 32. The electrolysis cell 18 is configured such that, in a stacked arrangement of several electrolysis cells 18 to form a stack arrangement 16, the oxygen is released from the stack arrangement 16 into the interior 14 of the housing 12.

[0064] Glass seals 44, 46 on the hydrogen side and on the oxygen side of the interconnector 22 ensure a gas-tight seal between electrolysis cells 18 stacked in a stack arrangement 16, in particular between the interconnectors 22 of directly adjacent electrolysis cells 18, such that the reactant gas manifold structure 66 and the product gas manifold structure 68 are fluidically separated from one another with respect to the interior space 14 of the housing 12. The glass seal 46 on the hydrogen side of the interconnector 22 is arranged such that it completely surrounds the interconnector 22 in the edge region of its hydrogen side. In the assembled state of the stack arrangement 16, the glass seal 44 seals a first interconnector 22, in the stacking direction S, on its hydrogen side, from a second interconnector 22, arranged adjacently in the stacking direction S, on its oxygen side.The glass seals 44, 46 interact with the interconnectors 22 of stacked electrolysis cells 18 in such a way that, on the one hand, a fluidically conductive connection is formed between the hydrogen sides of the directly stacked MEA 20 and interconnector 22, the reactant gas manifold structure 66 for the reactant gas, and the product gas manifold structure 68 for the product gas. Furthermore, the glass seals 44, 46 interact with the interconnectors 22 of stacked electrolysis cells 18 in such a way that the space between the oxygen sides of the directly stacked MEA 20 and interconnector 22 is fluidically connected to the interior 14 of the housing 12 of an electrolysis arrangement 10.

[0065] On the oxygen side of the MEA 20, as shown in Fig. 2, support elements 48 can be provided between the MEA 20 and the interconnector 22. These support elements serve to compensate for mechanical stresses between the MEA 20 and the interconnector 22, in particular caused by temperature differences. The support elements 48 are preferably made of glass or a glass ceramic and are therefore also called glass pins. When the electrolysis cell 18 heats up, mechanical stresses arise due to the different thermal expansion coefficients of the different materials of the various components of the electrolysis cell 18. With a thickness of well under one millimeter, for example, 80 μm, preferably 30 μm, the MEA 20 is a fragile structure that can crack or break under mechanical stress. In particular, localized compressive loads lead to fractures in the MEA 20.The support elements 48, together with the seals 44, 46, ensure that the MEA 20 does not warp when the electrolytic cell 18 heats up. The support elements 48 can be arranged at least partially in recesses 64 of the MEA 20, wherein the recesses 64 are preferably incorporated into the MEA 20 in a non-penetrating manner. The recesses 64 are preferably incorporated into a first layer of the MEA 20. Alternatively, the recesses 64 are formed by applying multiple layers to the MEA 20, with certain layers not being applied in certain regions.

[0066] Figure 3 shows a simplified exploded diagram in schematic form of the general structure of a stack arrangement 16. In the example shown in Figure 3, the stack arrangement 16 has three MEAs 20, i.e., three levels. The stack arrangement 16 according to the invention can alternatively comprise fewer or more MEAs 20 and thus correspondingly more levels. The number of levels depends on the desired performance of the electrolysis arrangement 10. On the ceiling side, above the last MEA 20 in the stacking direction S, the stack arrangement 16 terminates with a top plate 40. On the bottom side, below the first MEA 20 in the stacking direction, the stack arrangement 16 terminates with a base plate 42.

[0067] Three electrolysis cells 18 are arranged above the base plate 42. In the example shown, the electrolysis cells 18 each comprise a mesh-like metal mesh 38, preferably made of nickel mesh, an MEA 20, two glass seals 44 provided for sealing the manifold openings 28, 30 of the interconnectors 22, an interconnector 22, and another glass seal 46 provided for sealing the edge region of the interconnectors 22. The mesh-like metal mesh 38 is optional. The mesh-like metal mesh 38 can form a gas-conducting structure and can also serve to mechanically support the MEA 20 on the interconnector 22. The base plate 42 is in this case designed on its upper side analogously to a hydrogen side of an interconnector 22 and is sealed with a glass seal 46 arranged on the upper side relative to the interconnector 22 of the first electrolysis cell 18 in the stacking direction S.The third and final electrolysis cell 18 in the stacking direction S has, instead of an interconnector 22, a top plate 40, which is configured on its underside analogously to the oxygen side of an interconnector 22. Unlike the interconnectors 22, the top plate does not have manifold openings 28, 30. The top plate 40 closes the stack arrangement 16 at the top in the stacking direction S and seals the reactant gas and product gas manifold structures 66, 68 formed in the stack arrangement 16.

[0068] The stack arrangements 16 according to the invention can have a few, for example, 30 or 60, or many, for example, 400 to approximately 900 levels. Stack arrangements 16 with more than 900 levels are also conceivable in principle, although it should be noted that the requirements for the mechanical stability of the arrangement increase with the number of levels.

[0069] Directly below the top plate 40 of the stack arrangements 16, a further interconnector 22 (not shown) or a connector plate (not shown) can be inserted between the uppermost MEA 20 and the top plate 40. The connector plate is preferably electrically conductive in order to realize an electrical connection between the stack and the top or bottom plate, and further preferably has a non-stick coating. The non-stick coating serves to mechanically decouple the stack from the top or bottom plate. The connector plate can additionally have a structure designed such that, when the temperature changes, the different thermal expansions of the different materials can be mechanically compensated, in particular transversely to the stacking direction.

[0070] Figures 4a, 4b, and 4c show three schematic partial sections of the cross-section of a stack arrangement 16 with a tapered cross-section of a manifold structure 66, 68. In particular, Figures 4a-c each show a tapered manifold structure 66, 68, in which the taper extends from the base plate 42 across the electrolysis cells 18 stacked one above the other in the stacking direction S to the top plate 40 sealingly closing the manifold structure 66, 68. The taper can be provided in the reactant gas manifold structure 66 and / or in the product gas manifold structure 68.

[0071] In the example according to Figure 4a, the tapering of the manifold structure 66, 68 is implemented by means of the manifold openings 28, 30 incorporated into the interconnectors 22. As schematically indicated, the interconnectors 22 have manifold openings 28, 30 of different sizes for this purpose, with the interconnectors 22 of individual electrolysis cells being selected and the electrolysis cells 18 being stacked in such a way that a tapered structure results in the stack arrangement 16. As shown, this can in particular produce an approximately wedge-shaped structure. A wedge shape is achieved, for example, if the manifold openings 28, 30 of the interconnectors 22 are each approximately rectangular with two side lengths and the manifold openings 28, 30 narrow upwards along one side length in the stacking direction S. Alternatively, the tapered structure can also be approximately conical in shape.A pyramid shape or truncated pyramid shape is achieved, for example, if the manifold openings 28, 30 of the interconnectors 22 are each approximately rectangular with two side lengths, and the manifold openings 28, 30 narrow upwards along both side lengths in the stacking direction S. Figure 4b shows a tapered manifold structure 66, 68, in which the taper is implemented by means of an insert body 50 inserted into the manifold structure 66, 68. The interconnectors 22 of the individual electrolysis cells 18 each have manifold openings 28, 30 of the same size. Identical interconnectors 22 can thus be used to provide the individual electrolysis cells 18 of a stack arrangement 16, which significantly reduces the manufacturing effort. To form the taper, the insert body 50 is inserted into the manifold structure 66, 68 formed by means of the manifold openings 28, 30.The insert body 50 can - as shown - have an approximately triangular cross-section in the stacking direction S, so that a wedge-shaped tapered structure is realized.

[0072] Figure 4c shows a special form of a tapered manifold structure 66, 68 produced by means of an insert body 50. As in the embodiment according to Fig. 4b, the interconnectors 22 of the individual electrolysis cells 18 each have manifold openings 28, 30 of the same size. In contrast to the embodiment in Fig. 4b, the insert body 50 does not have a straight-line tapered surface, but rather a curved one. This creates a curved, tapered manifold structure 66, 68, which enables a particularly laminar flow of the reactant gas or product gas into or out of the electrolysis cells 18.

[0073] Figure 5 shows a stack arrangement 16 in which, to illustrate details, only the interconnectors 22 of individual electrolysis cells 18 are shown. The interconnectors 22 each have at least one orientation feature 60, in the example shown here, a reactant gas line structure 32 formed with guide channels, two manifold openings 28, 30, and on two opposite sides at the edge, in each case, a contact device 52 - in the example shown as an elongated hole - for establishing an electrically conductive contact with the interconnector 22. In addition to the contact device 52 designed as an elongated hole, a recess 54 is incorporated into the edge region of the interconnector 22 on each of the two opposite side edges of the interconnector 22.The contact device 52, designed as an elongated hole in the example shown, can be used to connect measuring devices for testing the stack arrangement, for example to identify defective electrolysis cells. In this embodiment, the interconnectors 22 are stacked one on top of the other, each rotated by 180°, so that the contact devices 52 designed as elongated holes and the recesses 54 are arranged alternately one above the other in the stack. The orientation feature 60 serves to avoid errors during stacking and to enable immediate or early error detection and prevention through technical precautions or devices. The idea for this originates from the poka-yoke principle. If a stacked stack arrangement 16 is only joined after stacking, an error in the stack can no longer be corrected. As long as the stack arrangement 16 is not yet joined, a stacking error can still be corrected.

[0074] Figures 6a and 6b each show an interconnector 22 with a glass seal 46 arranged on the hydrogen side of the interconnector 22. As shown in a detailed view of Figures 6a and 6b, the glass seals 46 can be applied to the interconnector 22 in a special shape. In the present case, Fig. 6a shows a meandering pattern, and Fig. 6a shows a zigzag pattern of the glass seal 46 applied to the interconnector 22. Other patterns are also conceivable. This special application pattern increases the length of the band-shaped glass seal compared to a straight pattern. This allows a larger surface area of ​​the sealing material to be provided with the same amount of sealing material compared to a straight pattern, which enables better degassing of the sealing material during a subsequent sintering process. This improved degassing can accelerate the sintering process.Alternatively, the same area can be sealed using less sealing material. This saves sealing material because less material is applied, the sealing performance is not compromised, and excess sealing material that can escape from the stack during sintering is avoided.

[0075] Figure 7 schematically shows a connector plate 36, which can be arranged, for example, below a top plate 40 or above a base plate 42. The connector plate 62 has a coating 62 on at least one side. The coating 62 can - as in the example shown - be arranged in the manner of a checkerboard pattern on the surface of the connector plate 36. A coating can also be present on the side of the connector plate 36 not shown. Figure 8 shows, very schematically, examples of channel cross-sectional shapes of a reactant gas line structure 32 designed as a channel structure on the hydrogen side of an interconnector 22. The channel structure shown is shown in a sectional view. As the figure shows, the channels 70 can be separated from one another by means of two channel webs 72 arranged adjacent to one another. The example shown illustrates conceivable cross-sectional shapes of the channel webs 72 andthe cross-sectional shapes of the channels 70 thus formed. An MEA 20 (not shown) is arranged above the channel webs 72 in the stack arrangement 16. The channels 70 are limited at the bottom by the body of the interconnector 22 or a coating present on the interconnector 22. At the top, the channels 70 are open towards an MEA 20 (not shown) arranged above them. For the electrolysis process, the reactant gas guided in the channels 70 comes into contact with the MEA 20 at the open upper sides of the channels 70. In order to also provide a sufficient amount of reactant gas in the edge region of the channels 70 for contact with the MEA 20, it is provided that the flank steepness F of the side walls of the channel webs 72 is greater than or equal to 85°. The flank steepness is referred to as the median of the plane defined by the plate-shaped interconnector 22.

[0076] LIST OF REFERENCE SYMBOLS

[0077] 10 Electrolysis arrangement 50 Insert body

[0078] 12 Housing 52 Contact device

[0079] 14 Interior 54 Recess

[0080] 16 stack arrangement 56 meandering structure

[0081] 18 electrolysis cells 58 zigzag structure

[0082] 20 Membrane electrode assembly 60 Orientation feature

[0083] 22 Interconnector 62 Coating

[0084] 24 reactant gas openings 64 recesses

[0085] 26 Product gas opening 66 Educt gas manifold structure

[0086] 28 Manifold opening 68 Product gas manifold structure

[0087] 30 manifold opening 70 channels

[0088] 32 Educt gas line structure 72 channel webs

[0089] 34 oxygen-permeable structure

[0090] 36 Connector plate S stacking direction

[0091] 38 net-like metal mesh F flank steepness

[0092] 40 top plate

[0093] 42 base plate

[0094] 44 Glass seal

[0095] 46 Glass seal

[0096] 48 support elements

Claims

CLAIMS 1. An electrolysis arrangement (10) comprising at least one housing (12) with an interior space (14), and at least one stack arrangement (16) arranged in the interior space (14) of the housing (12), wherein the stack arrangement (16) comprises a plurality of electrolysis cells (18) stacked in a stacking direction (S), wherein at least some of the electrolysis cells (18) each comprise a membrane electrode assembly (MEA) (20) and an interconnector (22), and wherein the membrane electrode assembly (20) and the interconnector (22) each have an oxygen side and a hydrogen side, characterized in that at least some electrolysis cells (18) have support elements (48) between the membrane electrode assembly (20) and the interconnector (22), and wherein the support elements (48) are designed and configured such that they are viscous in an operating state of the electrolysis arrangement (10) and solid in a rest state of the electrolysis arrangement (10).

2. Electrolysis arrangement (10) according to claim 1, characterized in that on the oxygen side of at least some membrane electrode arrangements (20) there is at least one layer which has recesses (64) for receiving the support elements (48), and wherein the layer having the recesses (64) is preferably an oxygen-permeable structure (34) by means of which oxygen released on the oxygen side of the membrane electrode arrangement (20) can be diverted to a side edge of the membrane electrode arrangement (20).

3. Electrolysis arrangement (10) according to claim 1 or 2, characterized in that the support elements (48) and / or the recesses (64) have a contour shape selected from the group consisting of circular, circular segment-shaped, square, rectangular, quadrangular, triangular or diamond-shaped.

4. Electrolysis arrangement (10) according to at least one of the preceding claims, characterized in that the surface area of ​​the projection surface of a support element (48) is approximately 5-15% of the surface area of ​​the membrane-electrode arrangements (20) of the electrolysis cell (18) to which reactant gas can flow.

5. Electrolysis arrangement (10) according to at least one of the preceding claims, characterized in that the surface size of the projection surface of the support elements (48) is smaller than the surface area of ​​the recesses (64) for receiving the support elements (48).

6. Electrolysis arrangement (10) according to at least one of the preceding claims, characterized in that at least some interconnectors (22) are designed as a flat, in particular plate-shaped component which is free of gas-conducting structures on the hydrogen side and / or on the oxygen side, wherein these interconnectors (22) are preferably designed as a flat steel sheet.

7. Electrolysis arrangement (10) according to at least one of the preceding claims, characterized in that at least some of the electrolysis cells (18) comprise a net-like metal mesh (38), preferably comprising nickel, in particular an iron-nickel alloy, which is arranged between the membrane electrode arrangement (20) and the interconnector (22).

8. Electrolysis arrangement (10) according to at least one of the preceding claims, characterized in that at least some components of the stack arrangement (16), such as membrane electrode arrangements (20), interconnectors (22), connector plates (36), top plate (40) and / or bottom plate (42) each have an orientation feature (60) by means of which the components can be aligned in the stack assembly in order to produce the stack arrangement (16), in particular according to the poka-yoke principle.

9. Electrolysis arrangement (10) according to at least one of the preceding claims, characterized in that at least some interconnectors (22) in the stack arrangement (16) are stacked alternately rotated by 180° using orientation features (60) arranged on the interconnectors (22).

10. Electrolysis arrangement (10) according to at least one of the preceding claims, characterized in that the stack arrangement (16) has a top plate (40) delimiting the stack arrangement (16) upwards in the stacking direction (S) at the top and a bottom plate (42) delimiting the stack arrangement (16) downwards in the stacking direction (S).

11. Electrolysis arrangement (10) according to claim 10, characterized in that the coating of the top plate (40) and / or the bottom plate (42) comprises a semiconducting oxide ceramic, in particular a ceramic comprising lanthanum (La), strontium (Sr), manganese (Mn) and / or cobalt (Co), preferably lanthanum-strontium-manganese-cobalt (LSMC), manganese cobalt iron oxide (MCF), lanthanum strontium manganite (LSM), lanthanum-strontium-cobalt-iron oxide (LSCF), or lanthanum-manganese-cobalt (LMC).

12. Electrolysis arrangement (10) according to at least one of the preceding claims, characterized in that the top plate (40) and the base plate (42) each have clamping devices, in particular in the form of holding elements projecting outwards at the edge region of the top plate (40) and the base plate (42), such that clamping means can be arranged on the outside of the stack arrangement at a distance from the stack arrangement between the clamping devices of the top plate (40) and the base plate (42), by means of which a tensile force acting between the top plate (40) and the base plate (42) along the stack direction axis can be applied.

13. Electrolysis arrangement (10) according to at least one of the preceding claims, characterized in that at least some of the interconnectors (22) have in their edge region at least one contact device (52) which is electrically conductively connected to the interconnector (22).

14. Electrolysis arrangement (10) according to claim 13, characterized in that the contact device (52) comprises a hole, in particular an elongated hole (52), machined into the edge region of the interconnector (22).

15. Electrolysis arrangement (10) according to claim 13 or 14, characterized in that the interconnectors (22) each having at least one contact device (52) are designed and / or arranged within the stack arrangement (16) in such a way that the contact devices (52) of the interconnectors (22) of two electrolysis cells (18) stacked one above the other are arranged offset from one another transversely to the stacking direction (S).

16. Electrolysis arrangement (10) according to at least one of the preceding claims, characterized in that the stack arrangement (16) has a top plate (40) delimiting the stack arrangement (16) upwards in the stacking direction (S) at the top and a bottom plate (42) delimiting the stack arrangement (16) downwards in the stacking direction (S) at the bottom.

17. Electrolysis arrangement according to claim 16, characterized in that a connector plate (36) is arranged between the top plate (40) and the last membrane-electrode arrangement (20) in the stacking direction (S) and arranged below the top plate (40) and / or that a connector plate (36) is arranged between the bottom plate (42) and the first membrane-electrode arrangement (20) in the stacking direction (S) and arranged above the bottom plate (40).

18. Electrolysis arrangement according to claim 17, characterized in that the connector plate (36) is designed as a plate-shaped sheet, wherein the outer contour shape of the connector plate (36) corresponds at least substantially to the contour shape of the interconnector (22) arranged adjacent to the connector plate (36) in the stacking direction (S), and wherein the connector plate (36) is preferably free of gas-conducting structures.

19. Electrolysis arrangement according to claim 17 or 18, characterized in that the connector plate (36) has a coating (62) at least on one side, at least in some areas, in particular such that several spaced-apart surface areas of the connector plate (36) are coated, preferably in the form of a checkerboard pattern.

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