Device and method for carbon dioxide electrolysis or carbon monoxide electrolysis

Abstract

The invention relates to an anode-side half cell (38) for an electrochemical cell (10) of an electrolytic apparatus (12) for carbon dioxide electrolysis and / or carbon monoxide electrolysis, having - a separator (24) in the form of a diaphragm, which has an anode-side separator surface (40) and a cathode-side separator surface (42) opposite the anode-side separator surface (40), - a catalyst layer (44), which has a first catalyst surface (46) and a second catalyst surface (48) opposite the first catalyst surface (46), the first catalyst surface (46) facing the anode-side separator surface (40), and - a fluid-permeable anode plate (50), which has a first anode surface (52), the first anode surface (52) facing the second catalyst surface (48).

Description

[0001] Description

[0002] Apparatus and method for carbon dioxide or carbon monoxide electrolysis

[0003] The invention relates to an anode-side half-cell for an electrochemical cell of an electrolysis device for carbon dioxide electrolysis and / or carbon monoxide electrolysis. Furthermore, the invention relates to an electrochemical cell of an electrolysis device for carbon dioxide electrolysis and / or carbon monoxide electrolysis, comprising a cathode section having an electrical cathode connection, a gas diffusion electrode, a first feed connection for supplying carbon dioxide, and a first discharge connection for discharging electrolyzed substances at least partially formed during the intended operation of the electrochemical cell, and an anode section separated from the cathode section by means of a separator, comprising an electrical anode connection, an anode plate,The invention comprises a second inlet port for supplying a proton-donating substance and a second outlet port for removing electrolysis residues at least partially formed during the intended operation of the electrochemical cell, wherein the cathode and anode ports are configured to be electrically coupled to corresponding electrical connections of an energy source providing an electrolysis voltage. Furthermore, the invention relates to an electrolysis device for carbon dioxide electrolysis and / or carbon monoxide electrolysis. Finally, the invention also relates to a method for manufacturing an anode-side half-cell for an electrochemical cell of an electrolysis device for carbon dioxide electrolysis and / or carbon monoxide electrolysis.

[0004] Anode-side cells, electrochemical cells, electrolysis devices for carbon dioxide electrolysis and / or carbon monoxide electrolysis, as well as methods for manufacturing anode-side cells, are fundamentally known in the prior art, so that no separate written proof is required. Electrochemical cells and electrolysis devices derived from them serve to convert carbon dioxide, at least partially, into carbon monoxide and / or other hydrocarbons. In addition to carbon dioxide, carbon monoxide can also be used alternatively or supplementarily to produce the other hydrocarbons, at least partially.

[0005] Carbon dioxide is a substance produced during the use of fossil fuels, in particular, and is released into the atmosphere in large quantities. Carbon dioxide is a greenhouse gas and therefore an undesirable substance in the atmosphere. The invention addresses the challenge of making carbon dioxide usable for a wide range of chemical industries. Carbon monoxide, on the other hand, is a starting material for the chemical industry and can be used to manufacture a variety of chemical products. This goal can be improved, if not achieved, by producing carbon monoxide from carbon dioxide. Furthermore, other hydrocarbons, such as methane, alcohols, and / or the like, can also be produced through carbon dioxide electrolysis. These other substances can also be obtained by the electrolysis of carbon monoxide.

[0006] In practice, it has been shown that the production of carbon monoxide, or other hydrocarbons, from carbon dioxide or carbon monoxide is not only very complex but also fraught with problems. For example, in carbon dioxide electrolysis, it is necessary that the carbon dioxide be at least partially converted into carbon monoxide through reduction. This requires providing a suitable environment for reduction as well as a substance whose oxidation allows the reduction of carbon dioxide. Therefore, in many applications, it is common to use an ion-conducting solution or a water-based electrolyte within the electrochemical cell.In the anode-side region of the electrochemical cell, the ion-conducting solution or the water-based electrolyte is split, allowing protons to be released and oxygen to be emitted. The water in the ion-conducting solution or the water-based electrolyte thus acts as a proton-donating substance. This part of the reaction typically takes place in the anode region.

[0007] After passing through a suitable separator, preferably one that is permeable only to protons, the protons can be made available in a cathode region of the electrochemical cell for the reduction of carbon dioxide. A reaction in the cathode region then at least partially splits the carbon dioxide, producing carbon monoxide. Furthermore, the released oxygen can then, for example, combine with the protons to form water.

[0008] The electrochemical cell typically has at least one cathode region and an anode region separated from the cathode region by a separator. To carry out the electrochemical reaction in the electrochemical cell, an anode is located in the anode region and a cathode in the cathode region, both of which are subjected to a suitable electrical potential. Furthermore, at least in the anode region, a catalyst is arranged to support or enable the desired reaction.

[0009] For the desired chemical reaction to take place in the electrochemical cell, the substances can be present in either a partially liquid or a partially gaseous state. If at least the carbon dioxide is supplied in gaseous form, the cathode can, for example, have a gas diffusion electrode. The gas diffusion electrode allows a solid, a liquid, and a gaseous substance to be brought into contact with each other, so that the desired electrochemical reaction can be achieved. A gas diffusion electrode is known, for example, from European patent application 19182 017.4.

[0010] The reaction in the electrochemical cell preferably utilizes an electrolyte. The electrolyte can, for example, be a preferably aqueous salt solution. If the salt solution is used as the electrolyte, the electrolyte can be the same on both the anode and cathode sides. The electrolyte can therefore be supplied from a single reservoir. Such an electrolyte is sometimes also called a monolyte. Furthermore, it is of course also possible to use different electrolytes in the anode and cathode regions, with the cathode region then containing a catholyte and the anode region an anolyte. In the anode region, the anolyte can be water, whereas the catholyte in the cathode region can be a salt solution. Other electrolyte configurations are also conceivable.

[0011] In electrolysis devices of this type, achieving a uniform current density across the intended reaction surface proves problematic, particularly with regard to the anode, in order to ensure optimal performance of the electrochemical cell. Substances that simultaneously serve as catalysts and provide electrical conductivity are especially problematic in this respect. Furthermore, arranging the various components in a predetermined position and connecting them in a predetermined manner, particularly on the anode side, has proven challenging. This results in complex assembly and construction. Reliability can be compromised both during the manufacturing of the electrochemical cell and during its intended operation. Similar problems can arise in the electrolysis of carbon monoxide.

[0012] The invention is based on the objective of improving a generic anode-side half-cell, an electrochemical cell, a generic electrolysis device, and also a method for their manufacture, so that the homogeneity of the current density in the area of ​​the anode is improved and the manufacture or construction of the electrochemical cell, in particular the anode-side half-cell, can be improved.

[0013] The invention proposes as a solution an anode-side half-cell, an electrochemical cell, an electrolysis device and a method for their manufacture according to the independent claims.

[0014] Advantageous further training opportunities arise from the characteristics of the dependent requirements.

[0015] With regard to a generic anode-side half-cell, it is particularly proposed that the anode-side half-cell comprises a separator designed as a membrane, which has an anode-side separator surface and a cathode-side separator surface opposite the anode-side separator surface, a catalyst layer which has a first catalyst surface and a second catalyst surface opposite the first catalyst surface, wherein the first catalyst surface faces the anode-side separator surface, and a fluid-permeable anode plate which has a first anode surface, wherein the first anode surface faces the second catalyst surface.

[0016] Furthermore, with regard to a generic electrochemical cell, it is particularly proposed that the anode area and the separator are designed as an anode-side half-cell according to the invention.

[0017] With regard to a generic electrolysis device, it is particularly proposed that the electrochemical cells are designed according to the invention, wherein the electrochemical cells are arranged spatially directly adjacent to one another.

[0018] With regard to a generic method, the invention specifically proposes that it comprises the following steps:

[0019] - Arranging an anode-side separator surface of a separator designed as a membrane, which has a cathode-side separator surface opposite the anode-side separator surface, on a first catalyst surface of a catalyst layer, which catalyst layer has a second catalyst surface opposite the first catalyst surface, and

[0020] - Arranging a first anode surface of a fluid-permeable anode plate on the second catalyst surface.

[0021] One aspect of the invention is the modular design of the electrochemical cell, which improves not only its efficiency but also its reliability and manufacturing technology. Furthermore, a modular structure allows for improved electrical coupling on the anode side with respect to the electrical anode connection, resulting in improved homogeneity of the anode's electrical current density. Overall, the invention simplifies assembly and increases its reliability, while also improving efficiency, particularly the Faraday efficiency, and reliability during operation. This, in turn, improves the overall efficiency of carbon dioxide electrolysis.

[0022] The anode-side half-cell is preferably a component that forms part of an assembly, in particular a modular assembly, of the electrochemical cell. Preferably, the anode-side half-cell is a separately handleable assembly. The anode-side half-cell provides the anode compartment and the separator and can therefore be easily connected to the other components or elements of the electrochemical cell. The design of the anode-side half-cell allows for the provision of a fully tested component for completing the electrochemical cell, thus simplifying the overall assembly process. Furthermore, the reliability of the assembly can be increased. At least the anode-side half-cell preferably has a stacked structure. In particular, its elements are arranged directly adjacent to one another.The stacked assembly can be at least partially fixed by means of mechanical connecting elements. The connection can be detachable or permanent. Furthermore, the anode-side half-cell can have its own housing or partial housing. The housing or partial housing can serve at least partially as a connecting element. In addition, clamps, clips, screws, rivets, and / or the like can be provided as connecting elements. Adhesives, solder, and / or the like can also be provided as connecting elements. These design features can, of course, be equally provided for the cathode-side half-cell or for the electrochemical cell comprising both the anode-side and cathode-side half-cells.

[0023] Preferably, a cathode-side half-cell can also be provided, comprising the corresponding elements of the cathode compartment. To complete the electrochemical cell, only at least these two elements—namely, the anode-side half-cell and the cathode-side half-cell—need to be combined and arranged together. Depending on the design and requirements, however, additional elements can also be provided.

[0024] In particular, it can of course be provided that the electrochemical cell has a housing in which at least the anode-side half-cell is arranged. This can also be provided for the cathode-side half-cell. However, at least on the cathode side, it can also be provided that some of the elements or components of the anode-side half-cell are arranged as individually manageable elements in a predetermined manner. They can then be connected to each other with mechanical connecting elements to achieve or fix the desired arrangement. The connecting elements can be, for example, clamping rings, screw connections, clip connections, and / or the like.

[0025] The electrochemical cell provides a reaction environment that allows the carbon dioxide, preferably supplied in gaseous form, to be at least partially converted into carbon monoxide. However, the carbon dioxide can also be supplied in liquid form using a solvent. This solvent can simultaneously act as an electrolyte for the electrochemical cell, or at least as a catholyte.

[0026] The electrochemical cell can, for example, have an electrical cathode terminal in the cathode region, which allows an electrical connection to be established to the electrical energy source that can supply the cathode terminal with an electrical cathode potential. The electrical cathode potential is different from the electrical anode potential and is preferably selected such that the desired electrochemical reaction can be achieved. The electrical potential difference between the electrical anode potential and the electrical cathode potential is, for example, about 7 V, preferably less than about 7 V, particularly preferably 5 V or less, especially about 3.8 V.

[0027] The cathode section further comprises a gas diffusion electrode, a first supply port for supplying carbon dioxide, particularly in gaseous form, and a first discharge port for discharging electrolytes at least partially formed during the intended operation of the electrochemical cell. The electrolytes include, in particular, the carbon monoxide produced by the intended electrolysis, which is also preferably in gaseous form. Furthermore, the electrolytes may also include residual carbon dioxide that was not converted during the intended operation of the electrochemical cells. Finally, other substances may be present as electrolytes, for example, water, especially in the form of water vapor, hydrogen, and / or the like.Depending on requirements, the electrolysis substances can be separated from each other by separation processes, so that in particular the carbon monoxide produced by the intended operation of the electrochemical cell can be separated from the other substances.

[0028] The separator is preferably a separator permeable to protons. Preferably, the separator is made exclusively of a proton-permeable material, for example, a substance such as Nafion or the like. The separator can also, for example, be an ion-conducting membrane, a porous material permeable to liquids, such as a frit or porous material on a support grid, polymer-bonded porous material, and / or the like, the aforementioned materials also serving, for example, as a support. The separator can be formed as a thin film or layer, particularly in the form of a membrane. Furthermore, the separator can also be integrally formed with at least one of the adjacent elements of the electrochemical cell, particularly with the catalyst layer. The catalyst layer is a layer that extends at least partially parallel to the separator.Preferably, the catalyst layer and an anode-side separator surface are bonded together to form a single unit. The catalyst layer comprises a suitable material that allows protons to be released from a proton-donating substance supplied to the anode region via a second feed port and transferred to the cathode region via the separator. The proton-donating substance can be, for example, water, a salt solution, and / or the like. The anode region can also have a second drain port for removing electrolysis residues that are at least partially formed during the intended operation of the electrochemical cell. If the electrolyte or anolyte is water, the residue can, for example, comprise oxygen, particularly in gaseous form.

[0029] Furthermore, the anode area can have an electrical anode connection which, like the cathode connection of the cathode area, can be electrically coupled to the electrical energy source, so that the anode of the anode area can be exposed to the electrical anode potential.

[0030] The separator has an anode-side separator surface and a cathode-side separator surface opposite the anode-side separator surface. Similarly, the catalyst layer has a first catalyst surface and a second catalyst surface opposite the first catalyst surface. The first catalyst surface faces the anode-side separator surface. "Facing" means, among other things, that the first catalyst surface and the anode-side separator surface are arranged opposite each other. Preferably, these surfaces can contact each other. Particularly preferably, these two surfaces are connected to each other, especially firmly connected, so that they can, for example, form an integral component. In particular, the catalyst layer can be arranged on the anode-side separator surface in the manner of a coating.This can improve the manufacturing of the electrochemical cell as well as the anode-side half-cell and also increase reliability in intended operation.

[0031] The anode-side half-cell further comprises the fluid-permeable anode plate, which has a first anode surface and a second anode surface opposite the first anode surface. The first anode surface faces the second catalyst surface. Here, too, the two surfaces can be arranged opposite each other. Preferably, these two surfaces are connected to each other, for example, rigidly connected. The anode plate is preferably made of a highly electrically conductive material, for example, titanium or a titanium alloy, or the like. Furthermore, the anode plate is preferably designed such that it allows the electrolyte, in particular the anolyte, to be supplied to the catalyst surface, specifically to the second catalyst surface. The anolyte, like the catholyte, can be liquid and / or gaseous.Furthermore, the design of the anode plate also allows for the removal of electrolysis residues from the area of ​​the second catalyst surface. This enables the electrochemical cell to operate continuously and as intended.

[0032] Preferably, the anode plate comprises a second anode surface opposite the first anode surface and a contact plate arranged on the second anode surface, wherein at least the anode plate or the contact plate serves for electrical connection to an electrical power source that provides an electrical anode potential. The contact plate reduces, if not completely eliminates, electrical voltage gradients during the intended operation of the electrochemical cell. The contact plate is arranged on the second anode surface and preferably makes contact with it not only mechanically but also electrically. At least the anode plate or the contact plate serves for electrical connection to the electrical power source. The contact plate is preferably also made of a highly electrically conductive material. Preferably, the contact plate is made of titanium or a titanium alloy.Furthermore, the contact plate can also incorporate additional highly electrically conductive structures, for example, made of a different material with good electrical conductivity, such as silver, silver alloys, copper, copper alloys, and / or the like. This design improves the uniform distribution of the anode potential across the second anode surface and thus also across the first anode surface, thereby reducing the effects of varying current density across the anode surface. This allows for better homogenization of the electrochemical cell's functionality across the available surface area, resulting in an overall improvement in efficiency.

[0033] The contact plate can be designed as a rigid plate and preferably has dimensions similar to the anode plate. The anode plate has dimensions, at least with respect to the first and second anode surfaces, that are preferably adapted to the second catalyst surface in order to achieve high functionality.

[0034] The cathode and anode terminals of the electrochemical cell are preferably designed to be electrically coupled to the corresponding electrical terminals of the energy source providing the electrolysis voltage. For this purpose, appropriate electrical connections can be provided that allow for electrical contact in the usual manner, for example, plug-in terminals, screw terminals, weld terminals, and / or the like.

[0035] Regarding the electrolysis unit, it is further proposed that the electrochemical cells be arranged in close proximity to one another. This allows for a compact design of the electrolysis unit overall, while also facilitating easy connection of the electrochemical cells. In particular, the first and second feed connections as well as the first and second discharge connections can be connected in parallel for flow control purposes, ensuring that the electrochemical cells are supplied with the required substances in a substantially uniform manner and that the corresponding products are simultaneously removed during normal operation of the electrochemical cell. Furthermore, the electrical interconnection of the electrochemical cells for normal operation can be easily achieved.

[0036] The electrochemical cells can be connected at least partially in series and / or parallel.

[0037] From a process engineering perspective, it is possible to position the anode-side separator surface against the first catalyst surface. This can be achieved, for example, by coating the anode-side separator surface with the catalyst. This ensures a reliable, strong connection between the separator and the catalyst. The second catalyst surface can then be connected to the first anode surface, for example, using an electrically conductive adhesive or similar material. Alternatively, the first anode surface can be biased against the second catalyst surface to achieve the necessary contact. Furthermore, a first layer of catalyst material can be applied to the first anode surface of the anode plate.The first layer of catalyst material formed in this way can be bonded to the first anode surface in the manner of a coating. A second layer of separator material can be applied to this catalyst material layer. Preferably, the second separator material layer is also bonded to the first catalyst material layer in the manner of a coating. This allows for the simple creation of a single-piece assembly. Of course, combinations of the aforementioned embodiments are also possible.

[0038] Furthermore, the contact plate can be positioned on the second anode surface to ensure good electrical contact between the anode plate and the contact plate. This allows the anode potential to be essentially homogeneous, preferably uniform across the anode plate, so that the anode potential is also available as homogeneously as possible on the second catalyst surface. At least the anode plate or the contact plate serves for electrical connection to the power source, for which purpose appropriate connection means can be provided to establish a reliable, electrically conductive connection to the power source. Separate connection means can be provided for this purpose, which contact the anode plate and / or the contact plate.In this way, a simple manufacturing process can be achieved, which is also well suited for mass production, especially automated mass production. This ensures reliability not only in the production of the electrochemical cells, particularly the anode-side half-cell, but also in their intended operation, as this manufacturing process allows for the guarantee of the most homogeneous and consistent manufacturing conditions possible.

[0039] Furthermore, it is proposed that the catalyst layer at least partially comprises iridium(IV) oxide. This material is particularly suitable for use as a catalyst for carrying out carbon dioxide electrolysis. Naturally, the iridium(IV) oxide can also be mixed with other substances that further improve its function as a catalyst, or at least enhance the mechanical properties of the catalyst layer. In addition, another metal oxide can also be used. Combinations of these are also possible.

[0040] According to a further development study, it is proposed that at least the anode plate or the contact plate should be made of titanium and / or a titanium alloy. Titanium has been shown to be particularly advantageous in the anode region for carbon dioxide electrolysis. At the same time, titanium provides good electrical conductivity, allowing the anode potential to be generated as uniformly as possible across the surfaces of the anode plate.

[0041] According to a further advantageous embodiment, it is proposed that the anode plate be at least partially porous. The porous design of the anode plate facilitates the simple introduction of the fluid anolyte or the proton-donating substance into the catalyst or catalyst layer. Known methods can be used to create the porosity. Furthermore, the anode plate can be provided with additional through-holes that open into the respective opposing anode surfaces. Depending on the design, these through-holes can be distributed evenly or asymmetrically across the anode surfaces.The porosity can be selected in a suitable manner depending on the viscosity and / or other physical properties, such as the temperature or the like of the anolyte and / or the proton-donating substance.

[0042] It is further proposed that the first anode surface be connected to the second catalyst surface by means of an electrically conductive connection technique. This electrically conductive connection technique enables a rigid bond between the first anode surface and the second catalyst surface, thus forming a single, preferably one-piece, assembly. Simultaneously, a highly conductive connection, preferably over the largest possible contact area, can be achieved between the first anode surface and the second catalyst surface. This allows the potential gradient with respect to the electrical anode potential to be largely reduced, if not essentially completely suppressed, during the intended operation of the electrochemical cell.Electrically conductive connection technology can be implemented, for example, by welding, gluing, soldering, combinations thereof, and / or similar methods. Using electrically conductive connection technology, a conductive connection can be achieved at multiple points and / or across an entire area, for example, over the entire contact surface or a predefined sub-area of ​​the contact surface.

[0043] Preferably, the joining technique utilizes an electrically conductive adhesive. This allows the first anode surface to be bonded to the second catalyst surface using the electrically conductive adhesive. This enables a simple and reliable bond between the first anode surface and the second catalyst surface, resulting in a strong, separately manageable assembly. Furthermore, this assembly can be tested separately for functionality, thus improving its reliability. For example, an electrically conductive adhesive based on 1-20 wt% PTFE, 1-20 wt% PVDF, or similar materials can be used. Additionally, epoxy resin- or cyanoacrylate-based adhesives can also be employed.

[0044] Preferably, the adhesive contains particles of iridium(IV) oxide. This allows for a particularly favorable transition between the adhesive and the catalyst. Therefore, the adhesive does not adversely affect the catalyst's performance; rather, it can further enhance the catalyst's effect.

[0045] The adhesive can be applied across the entire surface between the first anode surface and the second catalyst surface. Alternatively, the adhesive can be applied only partially between the two surfaces, for example, forming a predefined pattern or similar. This minimizes the amount of adhesive required while ensuring a reliable and strong bond between the surfaces.

[0046] It is further proposed that the second catalyst surface have projections extending from this surface, through the first anode surface and into the anode plate to connect with it. This allows for a further improvement in the connection between the second catalyst surface and the first anode surface. In particular, a transition zone can be achieved on the anode plate side of the first anode surface by already having catalyst material present, thus further improving the catalytic function. Overall, this can also improve the efficiency of the anode-side half-cell, and consequently, the efficiency of the electrochemical cell.

[0047] Furthermore, it is proposed that the protrusions be made of the same material as the catalyst layer. This not only ensures a good bond but also improves the function of the catalyst.

[0048] The protrusions can be designed to be pressed into the anode plate, thereby improving the bond between the first anode surface and the second catalyst surface. In particular, this can better absorb any shearing action between the two surfaces.

[0049] It is further proposed that the projections are formed by spaced-apart pins and that the anode plate, in particular the first anode surface, has receiving openings for the pins. This makes it possible to couple the anode plate to the catalyst layer, at least mechanically, but preferably also electrically, in the manner of a plug connection. For this purpose, the receiving openings can be adapted to the mechanical dimensions of the pins in order to enable an electrical connection in addition to a mechanical one. This further improves the homogeneity of the electrical anode potential in the region of the catalyst layer. The plug connection can be designed in the manner of a pin grid array (PGA), in which the contacts, here the receiving openings and the pins, are arranged in a predetermined grid.The contacts can also be arranged in a staggered pin grid array (SPGA) configuration, where the contacts are staggered in adjacent rows. To create the connection, the pins can be designed such that a predetermined insertion force is required. Preferably, the connection can be a low-insertion-force (LIF) connection. Alternatively, the connection can be a zero-insertion-force (ZIF) connection, where the connection can be made with virtually no force. In this case, a clamping device can be used to create a clamping connection between the pins and the receiving openings when the connection is inserted.The clamping connection can be actuated by means of a drive element, preferably manually operated, allowing switching between a locked and an unlocked state. This not only ensures a reliable connection but also allows the connection to be re-engaged. According to a further development, it is proposed that the contact plate has a contact plate surface opposite the second anode surface, which includes connecting elements for at least the mechanical connection of the contact plate surface to the second anode surface. This allows the contact plate to be mechanically firmly connected to the second anode surface. Furthermore, it is possible to simultaneously establish a good electrical connection between the second anode surface and the contact plate.This connection further improves the homogeneity of the anode potential of the anode plate. The contact plate is preferably also made of a highly electrically conductive material, which can be selected to be suitable for the anode plate. For example, the contact plate can also be made of titanium or a titanium alloy. Furthermore, the contact plate can also have at least partial connection areas made of a highly electrically conductive material such as silver, silver alloys, copper, copper alloys, and / or the like. In addition, the contact plate can also have corresponding conduction patterns across its surface, which further improve the overall electrical conductivity of the contact plate and thus further support the homogeneity of the anode potential.

[0050] Preferably, the connecting elements and the contact plate are electrically conductive. The connecting elements can, for example, be made of the same material as the contact plate. The connecting elements can be formed, for example, by projections on the contact plate. These projections can be designed to mechanically and electrically contact the second anode surface in a predetermined manner. This allows for a simple and reliable connection between the contact plate surface and the second anode surface, reducing, if not largely eliminating, gradients in the anode potential across the entire area of ​​the anode plate. The connecting elements can be connected to the second anode surface by means of a force. Alternatively, they can also be welded or soldered.

[0051] It is further proposed that the connecting elements and / or the projections are formed by spaced-apart pins. The pins can be arranged in a grid pattern on the contact plate surface. The pins preferably have a diameter smaller than the thickness of the contact plate. The pins can have a round or square cross-section along their longitudinal axis. Preferably, the pins are designed to establish good electrical contact on the anode side with the second anode surface and the anode plate.

[0052] For this purpose, axial ends can be formed with a mandrel or a hemispherical shape.

[0053] Regarding the electrochemical cell, it is further proposed that the cathode and anode components be arranged in a stack. Alternating the arrangement of these components allows for a modular layered structure, which is particularly advantageous for manufacturing. Furthermore, the resulting stack can be easily mechanically stabilized, making the electrochemical cell assembly manageable. Additionally, the electrochemical cell can be tested separately. This design is especially well-suited for the automated production of electrochemical cells.

[0054] The exemplary embodiments described below are preferred embodiments of the invention. The features and combinations of features specified above in the description, as well as those mentioned in the following description of exemplary embodiments and / or shown individually in the figures, are not only usable in the combinations specified, but also in other combinations. Thus, embodiments that are not explicitly shown and explained in the figures, but can be derived and generated from the described embodiments by separate combinations of features, are also to be considered disclosed by the invention.The features, functions, and / or effects illustrated by the embodiments can each, considered independently, represent individual features, functions, and / or effects of the invention, each of which further develops the invention independently. Therefore, the embodiments should also include combinations other than those described in the embodiments. Furthermore, the described embodiments can also be supplemented by additional features, functions, and / or effects of the invention already described.

[0055] FIG 1 shows a schematic functional block view of an electrolysis device for carbon dioxide electrolysis with a plurality of electrically connected electrochemical cells in series;

[0056] FIG 2 shows a schematic sectional view of an electrochemical cell of the electrolysis device according to FIG 1;

[0057] FIG 3 shows a schematic sectional view of the anode-side half-cell of the electrochemical cell according to FIG 2 in a first embodiment;

[0058] FIG 4 shows a schematic sectional view similar to FIG 3 in a second embodiment;

[0059] FIG 5 shows a schematic sectional view like FIG 3 in a third embodiment;

[0060] FIG 6 a schematic enlarged representation of area VI in FIG 5; FIG 7 a schematic sectional view based on FIG 3 in a fourth embodiment;

[0061] FIG 8 shows a schematic perspective view of a catalyst surface with projections shaped like pins, in the configuration according to FIG 7;

[0062] FIG 9 shows an enlarged view of area IX in FIG 8; and

[0063] FIG 10 shows a schematic top view of a first anode surface of an anode plate, which serves to connect with the catalyst layer according to FIG 8.

[0064] FIG. 1 shows a schematic functional block diagram of an electrolysis unit 12 for carbon dioxide electrolysis, in which, during normal operation, carbon monoxide is at least partially produced from carbon dioxide. The electrolysis unit 12 comprises a plurality of electrochemical cells 10 in which the carbon dioxide electrolysis takes place, two of which are shown as examples in FIG. 1. In the present embodiment, the electrochemical cells 10 are electrically connected in series, with the series connection being connected to an electrical power source 36 by means of electrical conductors 82 in order to supply the electrochemical cells 10 with electrical potentials at the respective electrodes, as will be explained below.

[0065] Each of the electrochemical cells 10 has a cathode region 14 and an anode region 26, which are separated from each other by a separator 24. The cathode region 14 comprises an electrical cathode terminal 16, a gas diffusion electrode 18 which is electrically coupled to the cathode terminal 16, a first supply terminal 20 for supplying carbon dioxide, and a first discharge terminal 22 for discharging electrolytes, including carbon monoxide, that are at least partially formed during the intended operation of the electrochemical cell 10. Furthermore, the electrolytes may also contain residual carbon dioxide that was not converted in the electrochemical cell 10. Other residual substances are also possible. The cathode region 14 is also connected to lines 30 for supplying and discharging a catholyte, in this case a salt solution.

[0066] The anode area 26 comprises an electrical anode connection 28, an anode plate 50 which is electrically coupled to the electrical anode connection 28, a second supply connection 32 for supplying a proton-donating substance, and a second discharge connection 34 for discharging electrolysis residues formed at least partially during the intended operation of the electrochemical cell 10.

[0067] The cathode terminal 16 and the anode terminal 28 are designed to be electrically coupled to a suitable or corresponding electrical electrolysis voltage from the electrical energy source 36. The respective first and second supply terminals 20, 32, as well as the respective first and second discharge terminals 22, 34, are each connected in parallel in a flow-optimized manner, so that the electrochemical cells 10 can be supplied from their respective sources for the corresponding substances during intended operation.

[0068] FIG. 2 shows a schematic sectional view of one of the electrochemical cells 10 according to FIG. 1. For clarity, the supply connections 20, 32 and the discharge connections 22, 34 are not shown. FIG. 2 shows a sectional view of one of the electrochemical cells 10. It can be seen that the electrochemical cell 10 has a stacked structure. The cathode region 14 comprises a catholyte element 74, which is adjacent to a gas diffusion electrode 18, which in this case at least partially represents the cathode. The gas diffusion electrode

[0069] 18 further adjoins a contact frame 76, which in this case is made of silver or a silver alloy. The contact frame 76 adjoins a gas spacer element 78, which serves, among other things, to supply carbon dioxide and remove carbon monoxide. The gas spacer element 78 adjoins a window 18, with which the cathode region 14 is closed. In alternative embodiments, an end plate or the like may be provided instead of or in addition to the window 18.

[0070] The catholyte element 74 is adjacent to the separator 24, specifically to a cathode-side separator surface 42. Opposite the cathode-side separator surface, the separator 24 has an anode-side separator surface. The separator 24 is made of a material permeable to protons. In the present embodiment, the material for the separator 24 is Nation. Of course, in alternative embodiments, another suitably appropriate material can be used.

[0071] The structure and function of the gas diffusion electrode 18 is described, for example, in the European patent application.

[0072] 19 182 017.4 is known. Therefore, reference is made to the relevant disclosure in this regard.

[0073] In the present embodiment, the anode section 26 is designed as a single unit together with the separator 24. This allows for the creation of a separately manageable unit, which simplifies the manufacture of the electrochemical cell 10 and improves its reliability not only during manufacturing but also during intended operation.

[0074] For this purpose, the separator 24 in the anode region 26 is designed with a catalyst layer 44 in the form of a membrane electrode assembly (MEA). The separator 24 is also designed as a membrane. The separator 24 has an anode-side separator surface 40 and an anode-side separator surface 40 facing the overlying cathode-side separator surface 42. Furthermore, the catalyst layer 44 has a first catalyst surface 46 and a second catalyst surface 48 opposite the first catalyst surface 46. The first catalyst surface 46 faces the anode-side separator surface 40. In the present embodiment, the first catalyst surface 46 is rigidly connected to the anode-side separator surface 40. The catalyst layer 44 can therefore be applied to the anode-side separator surface 40 in the manner of a coating.This results in a reliable, solid connection between the catalyst layer 44 and the separator 24.

[0075] The anode area 26 further comprises a fluid-permeable anode plate 50, which has a first anode surface 52 and a second anode surface 54 opposite the first anode surface 52. The first anode surface 52 faces the second catalyst surface 48. In the present embodiment, the first anode surface 52 is connected to the second catalyst surface 48. As will be explained below, this connection can be realized in different ways, according to the various embodiments discussed below.

[0076] The anode plate 50 is designed to be porous in order to achieve the desired gas permeability or the desired permeability for a liquid, for example water or the like.

[0077] A contact plate 56 is arranged on the second anode surface 54. The contact plate 56 has a contact surface 68 that is connected to the second anode surface 54. The contact plate 56 is electrically coupled to the electrical anode connection 28. An end plate 72 is arranged on a surface of the contact plate 56 opposite the contact surface 68, and this end plate 72 seals off the anode area 26 to the outside.

[0078] The separator 24, the catalyst layer 44, and the anode plate 50 form an anode-side half-cell 38 as a modular unit. Depending on the design and requirements, the modular unit can also include the contact plate 56. The anode-side half-cell 38, and in particular its structure, will be explained in more detail with reference to the following exemplary embodiments.

[0079] The catalyst layer 44 is predominantly composed of iridium(IV) oxide. However, depending on the desired functionality, other metal oxides or mixtures thereof can also be used.

[0080] The anode plate 50 and the contact plate 56 are made of a titanium alloy. This ensures good electrical conductivity, so that the electrical anode potential is as uniform and homogeneous as possible across the anode surfaces 52 and 54. This promotes the efficiency of the electrolysis process in the electrochemical cell 10.

[0081] Water or a salt solution can be used as the anolyte, which also provides the proton-donating substance, thus supplying protons for the desired electrochemical reaction of carbon dioxide electrolysis. A chemical reaction can be carried out at the anode according to the following equation:

[0082] At the cathode, a main reaction takes place according to the following chemical equation:

[0083] C02(g) + H20(l) + 2e — CO(g) + 20H

[0084] 2H20(l) + 2 e — ► H2(g)+ 20H

[0085] FIG. 3 shows a first embodiment of the anode-side half-cell 38. FIG. 3 shows that the second catalyst surface 48 is connected to the first anode surface 52 via an adhesive 58. In this embodiment, the adhesive 58 is a diffusion-open adhesive that forms a metallurgical bond between the second catalyst surface 48 and the first anode surface 52. The adhesive can, for example, contain PTFE, PVDF, or N-methyl-2-pyrroloidone as a solvent. Upon addition, N-methyl-2-pyrroloidone dissolves the two aforementioned polymers, and subsequently, after evaporation, a solid adhesive layer forms. In principle, however, other adhesives, for example, those based on epoxy resin or cyanoacrylate, can also be used.

[0086] The adhesive 58 preferably consists of the same or a similar substance as the separator 24. In general, it should be noted that if, as intended, Nafion is used as the material for the separator 24, which is a perfluorinated copolymer containing a sulfone group as an ionic group, a similar substance should be used for the adhesive, preferably one that does not introduce any foreign chemical components into the electrolysis process, so that the electrolysis process remains as unaffected as possible. The use of other adhesives is therefore essentially limited by the requirement that the electrolysis process is not significantly impaired.

[0087] The second anode surface 54 is mechanically and electrically connected to the contact plate 56 via connecting elements 70. The connecting elements 70 can provide a point connection or a continuous mechanical and electrical connection, for example by means of welding or adhesive spots, or by soldering or the like, depending on suitability.

[0088] In the present embodiment, the anode plate 50 is electrically coupled to the electrical energy source 36, specifically to its electrical anode potential. The contact plate 56 ensures that, even with a porous anode plate 50, a substantially homogeneous electrical anode potential is maintained across the anode surfaces 52 and 54, even at high current densities.

[0089] FIG. 4 shows a further embodiment of an anode-side half-cell 38 based on the embodiment according to FIG. 3. In contrast to the embodiment according to FIG. 3, in the embodiment according to FIG. 4 the adhesive 58 is replaced by the adhesive 60. The further structure corresponds to the embodiment according to FIG. 3.

[0090] The adhesive 60 can be designed in principle like the adhesive 58, but it additionally comprises fibers made of iridium(IV) oxide. This allows its function, particularly with regard to its catalytic effect, to be further improved. Otherwise, the structure of the anode-side half-cell 38 corresponds to the structure already explained with reference to FIG. 3. The adhesive 60 exhibits, in particular, a higher electrical conductivity than the adhesive 58.

[0091] FIG 5 shows a further embodiment for an anode-side half-cell 38 based on the embodiment according to FIG 4, for which further reference is made to the relevant explanations.

[0092] In the embodiment according to FIG. 5, iridium is applied to separator strips coated with iridium(IV) oxide fibers or iridium(IV) oxide, or optionally other plastic or metal fibers or strips, during the manufacturing of the separator 24 on one side of the separator 24, specifically on the anode-side separator surface 40. In a subsequent manufacturing step, the separator 24, which thus already contains the catalyst layer 44, is then connected to the first anode surface 52 of the anode plate 50. The connection can be made as explained with reference to FIGS. 3 and 4. In this way, the catalyst layer 44 can be mechanically bonded more securely to the separator 24.

[0093] The adhesive 58, 60 between the catalyst layer 44 and the anode plate 50 can be applied over the entire surface or at specific points, depending on the application. FIG 6 shows an enlarged section of FIG 5 in area VI.

[0094] FIG. 7 shows a further embodiment of an anode-side half-cell 38, which is fundamentally based on the embodiments described above according to FIGS. 3 to 6, for which further reference is made to the corresponding descriptions. In contrast to the embodiments according to FIGS. 3 to 6, no adhesive is provided in the embodiment according to FIG. 7. Instead, the second catalyst surface 48 of the catalyst layer 44 has projections 62 made of catalyst material, which extend through the first anode surface 52 into the anode plate 50. In this embodiment, the electrical energy source 36 is also electrically coupled to the contact plate 56. This allows for both a good electrical and mechanical connection and, at the same time, good efficiency with regard to the intended electrolysis of carbon dioxide. FIGS. 8 to 10 show an embodiment based on the embodiment according to FIG. 7.As can be seen in FIGS. 8 to 10, the membrane assembly consisting of the separator 24 and the catalyst layer 44 can be pluggably connected to the anode plate 50. This allows not only simple assembly but also easy detachment, enabling the anode plate 50 to be separated from the membrane assembly consisting of the separator 24 and the catalyst layer 44 if necessary. For this purpose, the embodiment according to FIG. 7 provides that the catalyst layer 44 has projections 62 as pins 66. These protrude from the second catalyst surface 48 (FIG. 8). FIG. 9 shows an enlarged section in area IX of FIG. 8.

[0095] FIG. 10 shows a schematic top view of the first anode surface 52 and the anode plate 50. It can be seen that receiving openings 64 are provided in accordance with the arrangement of the pins 66 of the catalyst layer 44 as shown in FIG. 8. When the catalyst layer 44 is connected to the anode plate 50, the pins 66 are inserted into the receiving openings 64. This ensures a reliable mechanical and electrical connection between the anode plate 50 and the catalyst layer 44.

[0096] Advantageously, the connection can be designed to be detachable. This can be achieved by applying a suitable separating force, allowing the anode plate 50 to be easily removed from the catalyst layer 44. However, a connection requiring virtually no force can also be provided, in which the anode plate 50 includes a locking element. This element allows the pins 66 to be inserted into the receiving openings 64 with minimal force in a first locking position and to be secured in the receiving openings 64 in a second locking position. This also enables simple, detachable assembly. Overall, the invention significantly simplifies the design of the electrochemical cell 10 and the electrolysis unit 12. Furthermore, it also increases reliability.Potassium bicarbonate, potassium sulfate, or similar substances can be used as the catalyte.

[0097] With the anode-side half-cell 38 according to the invention, a Faraday efficiency in the range of about 90% to 100%, preferably about 95%, can be achieved. The electrolysis preferably takes place in a temperature range above room temperature. Preferably, the temperature range can be selected from about 40°C to about 90°C, particularly preferably at about 60°C.

[0098] The following advantages can be achieved with this invention:

[0099] • A firm connection between a contact structure on an anodic side is achieved through a composite of the catalyst layer and the separator.

[0100] • Frequent contacting can ensure that the anode potential remains essentially uniform across the surface, even at high current densities.

[0101] • The assembly consisting of the separator and the catalyst layer is considerably less prone to swelling and therefore also less prone to buckling off the contact.

[0102] • The separator coating with the catalyst can be protected from mechanical abrasion during further handling in the manufacturing process or during normal operation.

[0103] • No great force is required to make contact.

[0104] • Improved handling in production and simplified assembly can be achieved. The aforementioned embodiments serve solely to illustrate the invention and are not intended to limit it.

Claims

An anode-side half-cell (38) for an electrochemical cell (10) of an electrolysis device (12) for carbon dioxide electrolysis or for carbon monoxide electrolysis, having- a separator (24) which is in the form of a membrane and has an anode-side separator surface (40) and a cathode-side separator surface (42) on the opposite side from the anode-side separator surface (40), - a catalyst layer (44) having a first catalyst surface (46) and a second catalyst surface (48) on the opposite side from the first catalyst surface (46), wherein the first catalyst surface (46) faces the anode-side separator surface (40), and- a fluid-permeable anode plate (50) having a first anode surface (52), wherein the first anode surface (52) faces the second catalyst surface (48). - wherein the second catalyst surface (48) has projections (62)that protrude from this surface and project into the anode plate (50) through the first anode surface (52) for bonding to the anode plate (50).The anode-side half-cell as claimed in claim 1, characterized in that the anode plate (50) has a second anode surface (54) on the opposite side from the first anode surface (52), where a contact plate (56) is disposed on the second anode surface (52) and where at least the anode plate (50) or a contact plate (56) serves for electrical connection to an electrical energy source (36) which provides an electrical anode potential.The anode-side half-cell as claimed claim 1, characterized in that at least the anode plate (50) or the contact plate (56) includes titanium or a titanium alloy.The anode-side half-cell as claimed in claim 1 , characterized in that the anode plate (50) is at least partly porousThe anode-side half-cell as claimed claim 1 , characterized in that the first anode surface (52) is connected to the second catalyst surface (48) by means of an electrically conductive bonding techniqueThe anode-side half-cell as claimed in claim 5, characterized in that the bonding technique uses an electrically conductive adhesive (58, 60), where the adhesive (60) includes particles of iridium(IV) oxide. The anode-side half-cell as claimed claim 1 , characterized in that the projections (62) are formed from the same material as the catalyst layer (44).The anode-side half-cell as claimed in claim 7, characterized in that the projections (62) are formed by mutually spaced pins (66) and the anode plate (50), the first anode surface (52), has receiving openings (64) for receiving the pins (66).The anode-side half-cell as claimed in any one of claims 2 to 8, characterized in that the that the contact plate (56) has a contact plate surface (68) which is on the opposite side from the second anode surface (54) and has connecting elements (70) at least for mechanical connection of the contact plate surface (68) to the second anode surface (54).The anode-side half-cell as claimed in claim 9, characterized in that the the connecting elements (70) and the contact plate (56) are electrically conductive. An electrochemical cell (10) of an electrolysis device (12) for carbon dioxide electrolysis or for carbon monoxide electrolysis, comprising- a cathode region (14) having an electrical cathode connection (20), for supply of carbon dioxide or carbon monoxide and a first drain connection (22) for draining of electrolysis substances at least partly formed in the intended operation of the electrochemical cell (10),- an anode region (26) which is formed separately from the cathode region (14) by means of a separator (24) and has an electrical anode connection (28), an anode plate (50), a second feed connection (32) for supply of a proton-releasing substance and a second drain connection (34) for draining of electrolysis residues at least partly formed in the intended operation of the electrochemical cell (10), - wherein the cathode connection (16) and the anode connection (28) are designed to be electrically coupled to corresponding electrical connections of an electrical energy source (36) that provides an electrical electrolysis voltage,characterized in that the anode region (26) and the separator (24) are designed as anode-side half-cell (38) as claimed in claim 1. The electrochemical cell as claimed in claim 11, characterized in that the elements of the cathode region and of the anode region (14, 26) are arranged in a stack. An electrolysis device (12) for carbon dioxide electrolysis or for carbon monoxide electrolysis, characterized by electrochemical cells (10) as claimed in claim 11 or 12, where the electrochemical cells (10) are in a spatially directly adjoining arrangement. A method of producing an anode-side half-cell (38) for an electrochemical cell (10) of an electrolysis device (12) for carbon dioxide electrolysis or for carbon monoxide electrolysis, comprising the steps of- arranging an anode-side separator surface (40) of a separator (24) which is in the form of a membrane and has a cathode-side separator surface (42) on the opposite side from the anode-side separator surface (40) at a first catalyst surface (46) of a catalyst layer (44), which catalyst layer (44) has a second catalyst surface (48) on the opposite side from the first catalyst surface (46), and- arranging a first anode surface (52) of a fluid-permeable anode plate (50) at the second catalyst surface (48) wherein the second catalyst surface (48) has projections (62) that protrude from this surface and project into the anode plate (50) through the first anode surface (52) for bonding to the anode plate (50).

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