WO2021198137A1 - Method for producing a gas- and/or electron-conducting structure and fuel/electrolysis cell - Google Patents

Abstract

The invention relates to a method for producing a gas- and electron-conducting structure for a fuel cell or electrolysis cell, to a method for producing a fuel cell or electrolysis cell, to a method for producing a fuel cell stack, to a gas- and electron-guiding structure for a fuel cell or electrolysis cell, to a fuel cell or electrolysis cell, and to a fuel cell stack. In a method for producing a gas- and electron-conducting structure (10) for a fuel cell (20) or electrolysis cell, material (12) is deposited on at least one region of a surface (30) in order to form the gas- and electron-conducting structure (10).

Description

Method for producing a gas and / or electron conduction structure and

Fuel / electrolysis cell

description

The invention relates to a method for producing a gas and / or electronic line structure for a fuel cell or electrolytic cell, a method for producing a fuel cell or electrolytic cell, a method for producing a fuel cell stack, a gas and / or electronic line structure for a fuel cell or electrolytic cell, a Fuel cell or electrolysis cell and a fuel cell stack.

Fuel cells are a promising way of generating electrical energy that does not require the direct emission of potentially harmful reaction products. Fuels for fuel cells, especially hydrogen, can be produced from excess electrical energy in times of current peaks, e.g. by means of electrolysis cells and stored for later use. Fuel cells are one option for emission-free drives for future climate-friendly mobility. In addition, there are already a large number of possible applications for fuel cells, such as for off-grid power supply for buildings and facilities. Since electrolysis cells, which are used, for example, to produce fuel for fuel cells, have a comparable (for example in the low temperature range such as alkaline or polymer electrolyte membrane electrolysers), e.g. In some cases, they even have an analog structure (e.g. solid oxide electrolysis cells in the high temperature range) like fuel cells, some developments in fuel cells can be directly transferred to electrolysis cells.

Since a single fuel / electrolysis cell does not provide sufficient electrical voltage for many practical applications, several cells are usually connected in series. In this case, the cathode of a first fuel cell is connected in an electrically conductive manner to the anode of a second fuel cell and the cathode of the second fuel cell, if necessary, is in turn connected to the anode of a third fuel cell. The anode in fuel cell operation can also be referred to as the fuel gas or fuel electrode and the cathode as the air electrode, whereas this in the Electrolysis operation is reversed. A series connection of several fuel cells can be implemented as a stack or fuel cell stack in which the individual fuel cells are stacked on top of or next to one another. In particular, the individual components are also stacked in layers within the fuel cell. The external electrodes of the external fuel cells are then used to derive the electrical current. Interconnectors are arranged between adjacent electrodes for mechanical and electrical connection. These contain gas line structures in order to transport the respective gas or gas mixture to each electrode or to discharge the gas or gas mixture that is formed. In addition, interconnectors are electrically conductive, so they also serve as an electron conduction structure in order to ensure the electrical contacting of the electrodes adjacent to them. Alternatively or in addition, the electrodes themselves can have gas and / or electron conduction structures.

The publication "Improved Robustness and Low Area Specific Resistance with Novel Contact Layers for the Solid Oxide Cell Air Electrode" by Talic et al., Published in ECS Transactions, discloses a contact layer with manganese, cobalt and copper to produce the electrically conductive connection. The publication "SOC Development at Forschungszentrum Jülich" by Blum et al., Also published in ECS Transactions, describes large solid oxide fuel cells. The publication "Analysis of the Cathode Electrical Contact in SOFC Stacks" by Kennouche et al., Published in the Journal of The Electrochemical Society, discloses contact layers for producing the electrical contact between the interconnector and the cathode of solid oxide fuel cells. The publication "Solid Oxide Fuel Cell Development at Forschungszentrum Juelich" by Blum et al., Published in Fuel Cells, describes the arrangement of a large number of solid oxide fuel cells in a fuel cell stack, with thick interconnectors made of chromium steel being arranged between the individual fuel cells. The publication "Investigation of Ni-coated steel meshes as alternative anode contact material to nickel in an SOFC stack" by Babelot et al., Published in the International Journal of Hydrogen Energy, describes network structures made of nickel and coated with nickel as a contact material between Anode and interconnector.

EP 2 859 608 B1 describes a gas distribution element made from formed sheet metal for a fuel cell, which is made up of several layers and has a contact surface perforated by openings Having contacting the fuel cell. EP 3 087 632 B1 discloses an interconnector with structures for distributing gas and means for adjusting a flow rate. GB 2 420 440 A describes a layer of a fuel cell stack which has a metal sheet with porous areas and gas distribution channels formed on at least one side of the sheet. WO 2015/144 970 A1 describes a fuel cell stack with several plates for conducting gas, a sealing arrangement and a gas-permeable contact structure.

The gas and / or electron conduction structures of conventional interconnectors are produced by reshaping, such as stamping sheet metal parts, which occurs in particular when using thin sheet metal. Due to the high tool costs, this is expensive and not very flexible. Alternatively, when using thicker sheet metal, gas ducts are produced using machining processes such as milling. This is tedious and therefore also expensive. The powder-metallurgical production of interconnectors is also known, which is also associated with significant costs. The interconnectors described are also largely complex to manufacture. The conventional interconnectors also have the disadvantage that they do not contact the electrode in the gas-conducting areas and thus do not allow electrical contact, which has to be compensated for by electrical cross-conduction, and on the other hand, do not allow gas to pass through in the areas contacting the electrode, which is compensated by gas diffusion must become. This means that the full capacity of the cells cannot be used, since there is an under-supply of gas in some areas and increased ohmic resistances in some areas.

A fuel cell 20 known from the prior art is shown schematically in FIG. This fuel cell, also referred to as a repeating unit, is intended to be arranged many times on top of one another in a fuel cell stack, also referred to as a stack. It comprises two electrodes 40, namely a cathode 41, also referred to as an air electrode, and an anode 42, also referred to as a fuel gas electrode. These are arranged on opposite sides of an electrolyte 64 and together with it form the basis of the fuel cell 20.

Above the anode 42 is the anode substrate 62, on which in turn a network structure 60 is arranged. The latter is used to make electrical contact with the anode 42 and to conduct the fuel gas to the anode 42. One such solution is not possible due to the corrosive conditions in the area of the cathode 41. The interconnector 44, which in the embodiment shown here is produced by milling a comparatively thick sheet metal, is used to make electrical contact with the cathode 41 and to conduct air to the cathode 41. By means of milling, flow channels 14 were produced on the above-illustrated side of the interconnector 44 in order to produce a gas and / or electron conduction structure 10 for the supply of air. To prevent the evaporation of chromium-containing substances, a protective layer 51 was then applied. In order to improve the electrical contact between the interconnector 44 or the protective layer 51 and the cathode 41, a contact layer 52 was applied to the cathode 41.

The area of the interconnector shown below is used when several fuel cells 20 are stacked one on top of the other, i.e. when a further fuel cell 20 is arranged directly below the fuel cell 20 shown, to seal between the air side of a fuel cell 20 and the fuel side of the fuel cell 20 below the interconnector 44 is the fluidic connection between the flow channels 14 for air and the network structure 60 for fuel gas. The fuel cell 20 shown here is expensive due to the elaborately manufactured interconnector 44 and requires a large amount of space.

Electrolysis cells use the reverse process with basically the same structure as that of the fuel cell. Here, the reaction is forced to proceed in the opposite direction by applying an electric current. This means that electrical energy is stored in chemical form, e.g. as hydrogen, and can later be converted back into electricity or used for other chemical processes.

It is the object of the invention to provide a further developed method for producing a gas and / or electron conduction structure for a fuel cell or electrolytic cell, a further developed method for producing a fuel cell or electrolytic cell, a further developed method for producing a fuel cell stack, a further developed gas and / or electron conduction structure for a fuel cell or electrolysis cell, a further developed fuel cell or electrolysis cell and a further developed fuel cell stack. A method for producing a gas and / or electron conduction structure for a fuel cell or electrolytic cell according to claim 1, as well as a method for producing a fuel cell or electrolytic cell, a method for producing a fuel cell stack, a gas and / or electron conduction structure for a fuel cell or electrolysis cell, a fuel cell or electrolysis cell and a fuel cell stack according to the dependent claims. Advantageous embodiments emerge from the subclaims.

The object is achieved by a method for producing a gas and / or electron conduction structure for a fuel cell or electrolysis cell, in which material is applied to at least one area of a surface to form the gas and / or electron conduction structure.

The method according to the invention is simple and inexpensive in comparison to the methods known from the prior art, since no shaping and no cutting method are necessary. A wide variety of materials can be applied and thus used to produce the gas and / or electron conduction structure. The provision of the material forming the surface or the material separating the two gas spaces is also particularly advantageous as a result of the invention, since a simple and inexpensive flat or flat component can be used for this. The method according to the invention can be used for any desired stack design.

The application of the material serves to form the gas and / or electron conduction structure. The formation of the gas and / or electron conduction structure means the production or formation of that three-dimensional structure which is used in the fuel cell or electrolysis cell of the gas line and / or the electron line, in particular for the purpose of making electrical contact. In particular, the applied material forms the gas and / or electron conduction structure on the surface. A pure coating of an already existing three-dimensional structure is therefore not a method according to the invention, since no gas and / or electron conduction structure is produced here.

A gas line structure is a three-dimensional structure for supplying or discharging gas or gas mixture to or from an electrode of a fuel cell or Electrolytic cell. The gas and / or electron conduction structure is at least partially gas-permeable. It can also be designed as a gas distribution structure. In some areas it can be suitable for guiding or redirecting a gas flow. A particularly high gas permeability of the gas line structure is desirable. The gas line structure produced with the method according to the invention is used in particular to supply fuel or oxidizing agent to an electrode and / or to discharge reaction product from an electrode. In the fuel cell or electrolysis cell, it is typically arranged on the side of the electrode facing away from the electrolyte. An electron conductive structure is an electrically conductive structure. In particular, it is used to make electrical contact with electrodes of a fuel or electrolysis cell, for example in a fuel cell stack. It can be used for the electrical connection of an anode of a first fuel cell and a cathode adjacent to the anode of a second fuel cell adjacent to the first fuel cell in a fuel cell stack.

Application means applying material to a surface. The surface of a component is meant. In particular, the material is a shapeless material. Typically the material is a liquid, pasty or powdery material or granulate. Accordingly, the application of the material can be an archetype process. If necessary, after the application of the material, the method comprises at least one further step in order to produce the gas and / or electron conduction structure, such as, for example, solidifying the material. In particular, the applied material is firmly connected to the surface or to the component forming the surface. However, it can also be present separately, for example in the case of an extruded material which is applied to the surface during assembly by inserting it.

The material can be, for example, lanthanum-strontium-cobalt-ferrite, also referred to as LSCF. It can be a material called LCC10. This is a Co- and Cu-doped La-Mn perovskite material. Lanthanum strontium manganate, LSM, or lanthanum strontium cobaltite, LSC, can also be used. In principle, any electrode material can be used, such as B. perovskites, spinels, fluorites, Ruddlesden-Popper phases, Brownmillerites and the like, as they are also used as air electrode material in a fuel cell or electrolytic cell. A fuel cell comprises two electrodes that are separated from one another by an electrolyte. The electrolyte is permeable to ions and can be configured as a liquid or solid. It can be designed as a membrane. The cathode is supplied with an oxidizing agent, for example an oxygen-containing gas or gas mixture. The anode is supplied with the fuel, for example hydrogen, natural gas or methanol. An electrical voltage is generated between the electrodes through an electrochemical reaction. The fuel cell is, in particular, a solid oxide fuel cell (SOFC), a high-temperature fuel cell whose electrolyte is designed as a ceramic solid.

In particular, the method according to the invention is used to produce a gas and / or electron conduction structure for a fuel cell, which is provided for use in a fuel cell stack. Here, as described, the task arises of providing gas and / or electron conduction structures for supplying fuel and oxygen and for removing reaction products between the individual fuel cells arranged in series.

The gas and / or electron conduction structure can also be produced for an electrolysis cell, also referred to as an electrolysis cell. It can be, for example, a solid oxide electrolysis cell (English: “solid oxide electrolyzer cell”, SOEC), ie a solid oxide fuel cell that can be operated in reverse mode. Everything that has been said in relation to a fuel cell according to the invention, including all process steps for producing the fuel cell and all parts thereof, applies accordingly to an electrolysis cell and vice versa.

In one embodiment, the gas and / or electron conduction structure is produced in such a way that at least one straight channel and in particular a plurality of straight channels arranged in parallel to the gas line are generated. A straight channel can run parallel to the direction of flow or at any angle to the direction of flow. Alternatively or in addition, a curved or winding channel can be created.

In one embodiment, a web with a width between 0.1 mm and 10 mm, in particular between 0.3 mm, is used as part of a gas and / or electron conduction structure and 5 mm and preferably between 1 mm and 3 mm. In one embodiment, material is applied in a layer thickness between 1 pm and 5 mm, in particular between 10 pm and 1 mm and preferably between 50 pm and 200 pm. This can be repeated as often as desired in order to produce the gas and / or electron conduction structure at the desired height. The gas and / or electron conduction structure can also be produced by just a single application of material, for example in the order of magnitude mentioned. The layer thickness is measured perpendicular to the surface.

In one configuration, the material is an electrically conductive material, in particular a metallic or ceramic material, so that the gas and / or electron conduction structure is set up to make electrical contact with an electrode.

The electrical contacting of an electrode is used for the electrical connection of an electrode to a line element or the electrical contacting of two adjacent electrodes in a fuel cell stack. The electrode is thus an electrode of the fuel cell or an electrode of an adjacent fuel cell in a fuel cell stack. In particular, the gas and / or electron conduction structure that is produced is used, in addition to the gas conduit, for the electrical connection of two adjacent electrodes. It can thus be referred to as a gas and electron conduction structure or as a gas conduction and contact structure.

Due to the above-described necessity of supplying and removing gases, direct flat contact with adjacent electrodes of a fuel cell stack is not possible. In a fuel cell stack that has been produced using this embodiment of the method according to the invention, the gas and / or electron conduction structure is thus located between two electrodes of adjacent fuel cells, more precisely between an electrode and the interconnector, which in turn is an anode of a first fuel cell and a Cathode of a second fuel cell separates from each other.

A metallic material is a material that has metallic properties. In particular, it comprises at least one metal in elemental form and / or as an alloy or intermetallic phase. This has the advantage of being similar in species the component forming the surface, for example the interconnector preliminary stage. The electrically conductive material can also be an electrically conductive ceramic material. In particular, an oxide ceramic is used.

This refinement has the advantage that the method is particularly simple and inexpensive, since no additional components for electrical contacting are necessary in addition to the gas and / or electron conduction structure.

In one configuration, the gas and / or electron conduction structure is produced in such a way that at least one flow channel remains between areas of applied material.

In other words, the material is applied in such a way that at least one flow channel is produced. A flow channel is an area of a gas and / or electron conduction structure, in particular a channel free of applied material, in which a gaseous medium can circulate unhindered. In other words, the flow channel is arranged in such a way that it is delimited by applied material on at least two sides, in particular opposite sides, of the flow channel. Material applied between areas means that there is at least one straight line on which a flow channel, that is to say an area free from the material, as well as material applied on both sides of this respective area, lie. In one embodiment, the flow channel has a width between 0.1 mm and 20 mm, in particular between 0.5 mm and 10 mm and preferably between 1 mm and 5 mm. The width of the flow channel is measured parallel to the surface.

In particular, the material is applied in the form of elongated elements such as, for example, webs, between which no material is applied. In general, a flow channel is not restricted in terms of its spatial extent, but in one embodiment it can have a longitudinal extent which is at least a factor of 5, in particular a factor of 10, greater than at least one and in particular both transverse extents oriented perpendicular to the longitudinal extent.

In one embodiment, at least a region of the surface remains free of the material for the purpose of forming a flow channel. In other words it will Material is only applied to certain areas of the surface and other areas of the surface remain free of the material. In particular, a large number of areas of the surface remain free of the material for the purpose of forming flow channels.

In this way, particularly inexpensive fuel cells and electrolysis cells can be produced, since material is used particularly sparingly.

In one embodiment, the material is applied to a surface of a flat component, in particular a sheet metal part.

A flat component is a component which has a significantly smaller extent in a first direction of extent than in two directions of extent that are perpendicular to the first direction of extent and perpendicular to one another. In particular, a flat component is meant. The flat component can be a sheet metal part. Typically the surface is a flat surface. Typically, the second surface of the flat component opposite the surface is also a flat surface.

Due to the simple and cost-effective shape of the component having the surface, this configuration enables a particularly simple and cost-effective production of a fuel cell or electrolysis cell. For example, the electrode and / or an interconnector preliminary stage can thus be designed as a flat sheet metal, which considerably simplifies production and coating and considerably reduces costs. In addition, a particularly flat and thus space-saving design of a fuel cell or electrolysis cell can be implemented.

In one embodiment, the material is applied by means of a printing process, in particular by means of screen printing, pad printing or a 3D printing process.

In screen printing, the material is printed onto the surface with a squeegee through an object called a screen and having openings. The sieve is in particular a fine-meshed fabric. In particular, 3D screen printing is possible, in which the material is applied in layers by means of screen printing. In this case, the paste to be applied comprises, for example, a metallic or ceramic powder, a solvent and possibly a binder. The binder can go out the printed material are burned out, so that a porous material remains after a temperature treatment such as a heat treatment or sintering.

With pad printing, the material is applied to the surface by means of an elastic pad, in particular made of silicone rubber. The transfer of the material can be done by pressing it in different thicknesses.

In 3D printing, also known as additive manufacturing, the material is applied layer by layer to create a three-dimensional structure. The applied material can be solidified or hardened by means of physical and / or chemical processes. Depending on the material to be applied, different 3D printing processes are possible, such as laser beam melting, electron beam melting, laser sintering, 3D screen printing or DSD processes ("Shaping-Debinding-Sintering") such as "Binder Jetting" or green body production using "Fused Deposition Modeling" , "Fused Layer Modeling" or "Material Extrusion". These methods enable a particularly flexible production of the gas and / or electron conduction structure, since no component-specific tools are required and the shape of the gas and / or electron conduction structure can be freely selected. Processes are possible which solidify the material only selectively and in this way produce the gas and / or electron conduction structure.

In one embodiment, the material is applied by means of a casting process, in particular by means of film casting. A liquid material, also referred to as slip, is applied to the surface and wiped off with a doctor blade and / or distributed. The film is then formed from this in a subsequent drying process. The film can be solidified by a temperature treatment. This process is already being used to manufacture components for fuel cells and electrolysis cells, so that it can be implemented particularly easily and cost-effectively in existing processes.

In one embodiment, the material is applied by means of extrusion. A pasty mass is continuously pressed out of a shaping opening under pressure and a body called an extrudate is created with the Cross section of the opening. Extrusion is a proven and easy-to-use process.

In one embodiment, the material is applied using a spraying method, in particular with masking. Here, droplets or particles of a liquid or pasty material collide with the surface and are solidified or hardened there. Masking an area ensures that the corresponding area is not coated. The wide range of adjustable parameters enables this method to be used particularly flexibly, especially for irregularly shaped surfaces.

In one embodiment, the material is subjected to a heat treatment, for example sintered, after it has been applied. During sintering, the strength of the applied material increases without it being completely melted. This is done in particular with metallic or ceramic materials. In this way, a particularly strong, hard and thus permanent gas and / or electron conduction structure can be produced. A particularly advantageous thermal conductivity can also be achieved in this way. A heat treatment can fundamentally change the structure and / or increase the cohesion of the particles and thus generate a suitable gas and / or electron conduction structure.

In one embodiment, the applied material is used to produce a porous gas and / or electron conduction structure so that gases or gas mixtures can be supplied and removed through the applied material. Here, the applied material has interconnected cavities in its interior, which allow the supply and discharge of gaseous media. This can be done at least partially by means of diffusion.

The material to be applied is selected and / or processed in such a way that, after the gas and / or electron conduction structure has been produced, it enables the transport of gases or gas mixtures in its interior. A material is selected that forms a porous gas and / or electron conduction structure. A porous material can be used. The applied material can be treated in such a way that a porous structure is formed. For example, a binder of an applied material can be burned out to produce the porous structure. For example, the material is applied in the form of webs between which gas or gas mixture can circulate freely. Due to the porosity, the webs can be made wider than in conventional gas line structures, so that improved electrical contact is possible with good gas line at the same time.

A porous material enables the material to be arranged on almost or completely over the entire surface, so that complete electrical contact is ensured with simultaneous gas permeability. This means that neither locally increased ohmic resistances nor areas of local gas undersupply occur.

Alternatively, a dense gas and / or electron conduction structure can be produced by means of the applied material, so that a supply and discharge of gases or gas mixtures through the applied material is not possible. Thus, the supply and discharge of gases or gas mixtures can only take place between areas of applied material or, in other words, in cavities that remain free. In particular, an at least substantially and in particular completely gas-impermeable material is applied for this purpose.

In one embodiment, the material is applied flat to at least one area of the surface and in particular to the entire surface.

Two-dimensional application means a complete application and in particular also a uniform application. Flat application on the entire surface means flat application on the area of the surface which is provided for the formation of a gas and / or electron conduction structure. It is not excluded here that no material is applied to minor areas of the surface, in particular in the edge areas of the respective component. In the fuel cell or the electrolysis cell, these areas typically serve to connect and / or seal the layers and for this reason must, if necessary, remain free of material. These areas of the surface typically make up less than 20%, in particular less than 10%, and in one example less than 5% of the total area of the surface. In one configuration, the material is applied to a surface of an electrode, in particular a cathode.

In this embodiment, the surface of the electrode is used directly in order to form the gas and / or electron conduction structure thereon. In this way, a particularly good electrical contact is made possible, which enables a low resistance. Typically, the cell is made with a mechanical support structure, anode, electrolyte and cathode and then the material is applied to the surface of the electrode. Several such cells can now be combined to form a fuel cell stack. However, it cannot be ruled out that the material is applied to the electrode before it is brought into contact with the electrolyte.

In one embodiment, the material is applied, for example printed, to the fuel cell or electrolysis cell that has been manufactured or provided.

The fuel, for example hydrogen or methanol, is applied to the anode. Thus, reducing conditions usually prevail. A metallic network is often used here, for example comprising nickel, in order to achieve electrical contact with simultaneous gas permeability. On the other hand, an oxidizing agent, often an oxygen-containing gas or gas mixture, is present at the cathode. Due to the corrosive or oxidizing conditions due to high temperatures and the oxidizing agent, metallic meshes, as in the case of the anode, with the exception of very expensive noble metal meshes, cannot be used. The method according to the invention thus enables the production of a space-saving and corrosion-resistant gas and / or electron conduction structure also in the area of the cathode, without having to resort to expensive and complex gas and / or electron conduction structures that are formed on or in the interconnector by means of forming or machining processes.

In one embodiment, the material is applied to a surface of an interconnector precursor for the purpose of producing an interconnector.

Interconnectors are arranged between adjacent electrodes for mechanical and electrical connection. An interconnector is an element which is arranged between two adjacent fuel cells of a fuel cell stack, also referred to as a stack, and on the one hand the gas transport to and from at least one electrode is guaranteed and, on the other hand, the electrical contacting of the electrode is used. In addition, they serve as a seal between the fuel side of a fuel cell and the oxidizing agent side of an adjacent fuel cell. In particular, an interconnector ensures the gas transport to or from two adjacent electrodes of the two fuel cells and is used to make electrical contact with these two electrodes. These are in particular an anode and a cathode. The side located on one side of the interconnector can be referred to as the air side and is used to transport oxygen-containing operating gases to the cathode and to transport possible reaction products away from the cathode. The side of the interconnector facing away from the air side can be referred to as the fuel side and is used to transport fuel to the anode and to remove possible reaction products. An interconnector can also be referred to as a bipolar plate.

An interconnector within the meaning of the invention comprises in particular a gas and / or electron conduction structure. An interconnector precursor is a component from which an interconnector can be produced by applying material to form the gas and / or electron conduction structure. In this embodiment, the gas and / or electron conduction structure is thus formed directly on a surface of an interconnector. This configuration enables a particularly simple and inexpensive production of a fuel cell or electrolysis cell. The interconnector preliminary stage can be designed as a flat sheet metal, which also makes production and, if necessary, coating much easier and thus considerably reduces costs. There is no need for expensive processes such as milling or embossing.

In one embodiment, the applied material corresponds to the material of the component forming the surface. This can in particular be the material separating the gas spaces. In other words, material of the same type is applied to the surface. In one embodiment, a gas and / or electron conduction structure made of the material of an electrode is formed thereon. Thus, an electrode constructed from a uniform material is produced. For example, the material is lanthanum strontium cobalt ferrite, also known as LSCF, or LCC10. Other ceramic materials are also possible, as explained above. Applying material of the same type, for example by means of printing, enables a particularly simple process that enables a very firm connection and ensures optimum electrical conductivity. In one embodiment, a gas and / or electron conduction structure from the material of the interconnector precursor is formed thereon. In this way, an interconnector constructed from a uniform material is produced. The applied material is in particular a metallic material.

In one embodiment, a protective layer is applied to the applied material, at least in some areas, in order to prevent the evaporation of chromium-containing substances. The protective layer can comprise manganese oxide, consist of manganese oxide or be formed from a mixed oxide of, for example, manganese, cobalt and / or iron. However, the protective layer is not restricted to the aforementioned compounds. It serves to reduce or prevent the evaporation of chromium species from chromium-containing steels, from which, for example, interconnectors can be made, in particular during operation of the fuel cell or electrolysis cell. These are in particular gaseous chromium compounds that impair cell performance. The protective layer is applied in particular to the air side of interconnectors. This can be done with a spraying process such as wet powder spraying or plasma spraying. During the production of a fuel cell, a protective layer and / or a contact layer can be applied to an interconnector precursor or an interconnector. A contact layer can also be applied to a protective layer.

In one embodiment, a contact layer is applied to the applied material or to a protective layer, at least in regions, in order to improve electrical contacting. In the fuel cell or electrolysis cell, the contact layer improves the electrical contact between the gas and / or electron conduction structure and the component lying thereon, for example an electrode or an interconnector. The application can take place with a spraying method such as wet powder spraying, but is not limited to this.

The application of the protective layer and / or the contact layer turns out to be simpler and less error-prone due to the method according to the invention, since the application of the respective layer on flat areas is possible, which is the known problem of inadequate layer homogeneity in connection with application to three-dimensional structures and the associated problem associated decreased Protective effect fixes. A higher contour accuracy can be achieved. For example, the effective contact area can be increased. There is also no lens formation, which would further reduce the effective contact area.

A second aspect of the invention is a method for producing a fuel cell or electrolysis cell, comprising the production according to the invention of a gas and / or electron conduction structure.

In particular, the method further comprises the provision of an electrolyte and the provision of two electrodes arranged on opposite sides of the electrolyte, namely an anode and a cathode. The gas and / or electron conduction structure can take place on a surface of an electrode. The method can furthermore comprise the provision of an interconnector preliminary stage. In this case, the gas and / or electron conduction structure can take place on at least one surface of the interconnector preliminary stage for the purpose of producing an interconnector. The embodiments and features disclosed above in connection with the aspect of the invention described at the outset can also be applied to this aspect of the invention.

In one embodiment of the method, the material is applied to a surface of an electrode and a contact layer is applied at least in regions to an interconnector for contacting the gas and / or electron conduction structure of the electrode in order to improve electrical contacting. The contact layer consists in particular of the material applied to the surface of the electrode. Alternatively, for the purpose of producing an interconnector, the material is applied to a surface of an interconnector precursor and a contact layer is applied at least in some areas to an electrode for contacting the gas and / or electron conduction structure of the interconnector made from the interconnector precursor in order to establish electrical contact to enhance. The contact layer consists in particular of the material applied to the surface of the interconnector.

The material is applied directly or indirectly to the surface of the electrode or the interconnector precursor. For example, a further layer such as a protective layer can be arranged between them. The interconnector for contacting the gas and / or electron conduction structure of the electrode is an interconnector which is provided to contact the gas and / or electron conduction structure formed on the electrode in the fuel cell or electrolysis cell to be produced or in a fuel cell stack comprising the fuel cell. Here, too, it is of course possible for at least one further layer, such as a protective layer, to be arranged between them. The contact layer is therefore applied to at least one area of an interconnector, in particular one side of an interconnector, which is provided for direct or indirect contacting of the electrode. Analogously to this, the electrode for contacting the gas and / or electron conduction structure of the interconnector is an electrode that is provided in the fuel cell or electrolysis cell to be produced or in a fuel cell stack to be produced with the fuel cell that is on the interconnector that was produced from the interconnector preliminary stage to contact produced gas and / or electron conduction structure. Here, too, further layers, such as the protective layer, can be arranged between the components. The contact layer is therefore applied to at least one region of an electrode which is provided for direct or indirect contacting of the interconnector. The electrical contacting of the electrode and interconnector made of materials of the same type as described in this embodiment leads to an improved electrical contact and thus to a minimized contact resistance.

In one embodiment, the applied material corresponds to the material of the component that makes electrical contact with the gas and / or electron conduction structure. This includes that component which is provided for making electrical contact with the gas and / or electron line structure in the fuel cell or electrolysis cell or in a fuel cell stack comprising the fuel cell. The component can in particular be an interconnector or an electrode.

A third aspect of the invention is a method for producing a fuel cell stack, comprising the production according to the invention of a gas and / or electron conduction structure and / or the production according to the invention of a fuel cell. In particular, the method comprises the provision of a plurality of fuel cells. The gas and / or electron conduction structure can then be formed between two adjacent electrodes of two adjacent fuel cells. The embodiments and features disclosed above in connection with the aspect of the invention described at the beginning and with the method for producing a fuel cell or electrolysis cell can also be applied to this aspect of the invention.

An additional aspect of the invention is a method for producing a membrane module, in particular for gas separation, in which material is applied to at least one area of a surface to form the gas and / or electron conduction structure. In particular, a multi-layer membrane module and / or a membrane module composed of planar components is produced. The embodiments and features disclosed in connection with the other aspects of the invention can also be applied to this aspect of the invention.

Another additional aspect of the invention is an electrode for a fuel cell or an electrolysis cell, comprising a gas and / or electron conduction structure. This is produced in particular with the method according to the invention. The gas and / or electron conduction structure is in particular produced in one piece with the electrode or molded onto it. The embodiments and features disclosed in connection with the other aspects of the invention can also be applied to this aspect of the invention.

A fourth aspect of the invention is a gas and / or electron conduction structure for a fuel cell or electrolysis cell, comprising a material applied to at least one area of a surface to form a gas and / or electron conduction structure. In particular, the gas and / or electron conduction structure is produced using the method according to the invention. Typically, the applied material is firmly connected to the surface or to the component forming the surface.

A fifth aspect of the invention is a fuel cell or electrolysis cell, in particular a solid oxide fuel cell, comprising a gas according to the invention and / or electron conduction structure. In particular, this is produced with the method according to the invention.

A sixth aspect of the invention is a fuel cell stack. This comprises at least one gas and / or electron conduction structure according to the invention and / or at least one fuel cell according to the invention. In particular, this is produced with the method according to the invention. In particular, a gas and / or electron conduction structure is arranged between two adjacent electrodes of adjacent fuel cells. In particular, a gas and / or electron conduction structure is arranged between all adjacent electrodes of adjacent fuel cells.

A fuel cell stack is also referred to as a stack. The gas and / or electron conduction structure can be arranged on an interconnector arranged between the adjacent electrodes of the adjacent fuel cells and / or be formed on the surface of the interconnector. It can be arranged on at least one of the adjacent electrodes and / or formed on the surface of the electrode. The fuel cell stack can also be operated in reverse mode as an electrolysis cell, for example a solid oxide electrolysis cell. The embodiments and features disclosed in connection with the other aspects of the invention can also be applied to the fourth, fifth and sixth aspects of the invention.

In the following, further exemplary embodiments of the invention will also be explained in more detail with reference to figures.

Show it:

FIG. 1: a schematic representation of a fuel cell according to the prior art; and

FIG. 2: a schematic representation of a fuel cell according to the invention.

FIG. 1 has already been discussed in the course of the assessment of the prior art. In the simplified illustrations of both figures, frame parts and seals are not shown in each case. The same components in the two figures are provided with the same hatching. FIG. 2 shows a gas and / or electron conduction structure 10 produced by the method according to the invention in a fuel cell 20. This fuel cell 20 also comprises two electrodes 40, namely a cathode 41, also referred to as an air electrode, and an anode 42, also referred to as a fuel gas electrode. These are arranged on opposite sides of the electrolyte 64, which is optionally supplemented by a diffusion barrier, and together with this form the basis of the fuel cell 20.

Thin functional layers require a mechanical support structure to achieve manageable components. Such a support structure can be assigned to the electrolyte, one of the electrodes, or a separate substrate, so that the following types of construction are possible: “electrolyte / anode / cathode / inert / metal-supported cells”, abbreviated as ESC / ASC / CSC / ISC / MSC. The support layer used here is assigned to the anode 42 and is also referred to as the anode substrate 62. A network structure 60, which is designed here as a nickel network, is in turn arranged on this. This serves to make electrical contact with the anode 42 and as a spacer to an interconnector of a further fuel cell arranged above in a fuel cell stack and thus to conduct the fuel gas to the anode 42. As described, such a solution is not possible in the area of the cathode 41.

In the fuel cell 20 according to the invention, the gas and / or electron conduction structure 10 is used to conduct air to the cathode 41. To produce the gas and / or electron conduction structure 10, material 12 is applied to areas of the surface 30 of an electrode 40, namely the cathode 41 been. Areas that are free of applied material 12 are arranged between the areas of the applied material 12, which are designed in the form of webs. These are flow channels 14 in which air can freely circulate.

The material 12 is in particular applied layer by layer by means of a 3-D screen printing process and then sintered. It is an electrically conductive ceramic material 12 which, in addition to the function of gas conduction, also serves to conduct electrons, that is to say to make electrical contact with the cathode 41. In addition, it is a porous material which accordingly provides a porous gas and / or electron conduction structure 10, which also supplies and removes gases in the interior of the webs produced enables. In this way, the gas line is improved and wider webs are possible, which at the same time improve the electrical contact.

The material 12 was applied to a flat surface 30 of the cathode 41, which is designed as a flat component 32. In this way, a particularly inexpensive and space-saving cathode 41 was achieved. The material 12 can, for example, correspond to the material of the component 32 forming the surface 30, namely the cathode 41.

To prevent the evaporation of chromium-containing substances, a protective layer 51 was applied to the interconnector 44. In order in turn to improve the electrical contact between the interconnector 44 or the protective layer 51 and the material 12 forming the gas and / or electron conduction structure 10, a contact layer 52 was applied to the protective layer 51. In principle, it is also possible to apply the protective layer 51 to the gas and / or electron conduction structure 10, for example in order to save material. However, due to the interrupted surface of the gas and / or electron conduction structure 10, this is more complex and therefore not recommendable under certain circumstances. In principle, the contact layer can be applied to the cell, that is to say to at least one of the electrodes, and / or the interconnector.

The fuel cell 20, shown here in the form of a repeating unit, is also provided for arrangement in a fuel cell stack, also referred to as a stack, which is stacked one on top of the other. In this case, the lower side of the interconnector 44 of a fuel cell 20 consequently rests against the upper side of a network structure 60 of the adjacent fuel cell 20. The interconnector 44 serves as a gas-tight seal between the air side of the fuel cell 20 in the area of the cathode 41 and the fuel side of the fuel cell 20 in the area of the anode 42. List of reference symbols

Gas and / or electron conduction structure 10

Material 12

Flow channel 14

Fuel cell 20

Surface 30

Component 32

Electrode 40

Cathode 41

Anode 42

Interconnector 44

Protective layer 51

Contact layer 52

Network structure 60

Anode substrate 62

Electrolyte 64

In one embodiment, the material is applied by means of a printing process, in particular by means of stencil printing. Application by stencil printing is preferable to screen printing if dry film thicknesses of more than 150 μm are to be achieved and complex shapes with cutouts are not required.

In one embodiment, the material is applied using a method that is not a generative manufacturing method. Material is applied, but especially not in several layers. As a result, the process is significantly accelerated, particularly in comparison to the generative manufacturing process, so that industrial mass production is made possible or significantly simplified. In particular, the material is applied by means of screen printing, pad printing or a casting process, for example film casting, an injection molding process or by extrusion. The method can be a printing method.

In particular, the gas and / or electron conduction structure is designed in such a way that no further channel-shaped structures are required for gas supply, for example for gas supply to the active cell surface of a stack level. The gas and / or electron conduction structure can accordingly be the gas conduit alone guarantee. The gas line means the supply and discharge of the fuel gases and reaction products to / from the active cell surface. The interconnector then mainly serves to conduct electrons. Such a structure could be recognized by the fact that if the gas and / or electron conduction structure were removed from a given cell and if the adjacent components were in direct contact, an adequate gas supply to the active cell surface would no longer be guaranteed.

In particular, the gas and / or electron conduction structure is designed in such a way that it is used to make contact with the adjoining component, in particular the interconnector or the electrode. It is therefore not necessary to arrange an additional contact layer and / or protective layer between them. As described, however, it is possible to arrange an additional contact layer and / or protective layer.

In particular, the gas and / or electron conduction structure is not itself the (electrochemically active) electrode and / or the electrode is not located directly on the interconnector. The gas and / or electron conduction structure can be located between the electrode and the interconnector.

The material can be applied to a surface of a flat component. The flat component can, for example, be contoured for mechanical reinforcement. It can have form elements for stiffening.

In the event that the material is applied to a surface of an electrode, no gas line structures are required for the contacting component, in particular an interconnector. The interconnector can thus be designed as a flat component, which brings significant savings in terms of technical complexity and costs. Alternatively, the material can be applied to a flat interconnector precursor, which is provided, for example, with a protective layer and / or a contact layer, in order in this way to enable a flat component as an adjacent electrode.

In one embodiment, the cathode is essentially free of metal. This means that the cathode has a metal content based on the mass of less than 5%, in particular less than 1% and, for example, less than 0.5%. In particular, the fuel cell or electrolysis cell or the

Fuel cell stack constructed in such a way that the gas and / or electron conduction structure rests on a surface of an electrode. The interconnector is in turn in contact with the gas and / or electron conduction structure. This enables a flat and possibly even design of the interconnector. This can for example be designed as a sheet metal. It can be contoured as described.

A protective layer and / or a contact layer can be arranged between the surface and the gas and / or electron conduction structure. In particular, they can be arranged on the surface. A protective layer and / or a contact layer can be arranged between the gas and / or electron conduction structure and the interconnector. In particular, they can be arranged on the interconnector. The gas and / or electron conduction structure can comprise or consist of ceramic material.

Claims

Expectations 1. A method for producing a gas and / or electron conduction structure (10) for a fuel cell (20) or electrolytic cell, in which material (12) is used to form the gas and / or electron conduction structure (10) on at least one area of a surface (30) ) is applied. 2. The method according to claim 1, characterized in that the applied material (12) corresponds to the material of the component (32) forming the surface (30). 3. The method according to any one of the preceding claims, characterized in that by means of the applied material (12) a porous gas and / or electron conduction structure (10) is produced, so that a supply and discharge of gases or gas mixtures through the applied material (12 ) can take place through it. 4. The method according to claim 3, characterized in that the material (12) is applied flat to at least one area of the surface (30) and in particular to the entire surface (30). 5. The method according to any one of the preceding claims, characterized in that the material (12) is an electrically conductive material (12), in particular a metallic or ceramic material (12), so that the gas and / or electron conduction structure (10) for electrical contacting of an electrode (40) is set up. 6. The method according to any one of the preceding claims, characterized in that the gas and / or electron conduction structure (10) is produced in such a way that at least one flow channel (14) remains between areas of applied material (12). 7. The method according to any one of the preceding claims, characterized in that the material (12) is applied to a surface (30) of a flat component (32), in particular a sheet metal part or an electrode. 8. The method according to any one of the preceding claims, characterized in that the material (12) is applied by means of a printing process, in particular by means of screen printing, pad printing or a 3D printing process, that the material (12) is applied by means of a casting process, for example film casting, is applied by means of a spraying process or by means of extrusion, and / or that the material (12) is subjected to a heat treatment, in particular sintered, after application. 9. The method according to any one of claims 1-8, characterized in that the material (12) is applied to a surface (30) of an electrode (40), in particular a cathode (41). 10. The method according to any one of claims 1-8, characterized in that the Material (12) for the purpose of producing an interconnector (44) on a Surface (30) of an interconnector precursor is applied. 11. The method according to any one of the preceding claims, characterized in that a protective layer (51) is applied to the applied material (12) at least in some areas in order to prevent evaporation of chromium-containing substances, and / or that the applied material (12) or a contact layer (52) is applied to a protective layer (51) at least in regions in order to improve electrical contacting. 12. A method for producing a fuel cell (20) or electrolysis cell, comprising the production of a gas and / or electron conduction structure (10) according to any one of claims 1-11. 13. The method according to claim 12, characterized in that - The material (12) is applied to a surface (30) of an electrode (40) and a contact layer (52) is applied at least in some areas to an interconnector (44) for contacting the gas and / or electron conduction structure (10) in order to provide a to improve electrical contact, wherein the contact layer (52) in particular consists of the material (12) applied to the surface (30) of the electrode (40), or - the material (12) is applied to a surface (30) of an interconnector precursor for the purpose of producing an interconnector (44) and to a Electrode (40) for contacting the gas and / or electron conduction structure (10) of the interconnector (44), a contact layer (52) is applied at least in some areas in order to improve electrical contacting, the contact layer (52) in particular from being applied to the surface (30) of the interconnector (44) applied material (12). 14. A method for producing a fuel cell stack, comprising the production of a gas and / or electron conduction structure (10) according to one of claims 1-11 and / or the production of a fuel cell (20) according to one of claims 12 and 13. 15. Gas and / or electron conduction structure (10) for a fuel cell (20) or electrolysis cell, comprising a material (12) applied to at least one area of a surface (30) to form the gas and / or electron conduction structure (10). 16. Fuel cell (20) or electrolysis cell, in particular solid oxide fuel cell, comprising a gas and / or electron conduction structure (10) according to claim 15. 17. Fuel cell stack, comprising at least one gas and / or electron conduction structure (10) according to claim 15 and / or at least one fuel cell (20) according to claim 16, wherein in particular between two adjacent electrodes (40) of adjacent fuel cells (20) a gas and / or electron conduction structure (10) is arranged.