Apparatus and method for electrolysis of carbon dioxide or carbon monoxide

Abstract

The invention relates to an anode-side half-cell (38) for an electrochemical cell (10) of an electrolysis device (12) for carbon dioxide electrolysis and / or carbon monoxide electrolysis, the anode-side half-cell comprising a separator (24) configured as a membrane, the separator having an anode-side separator surface (40) and a cathode-side separator surface (42) opposite the anode-side separator surface (40), a catalyst layer (44) having a first catalyst surface (46) and a second catalyst surface (48) opposite 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).

Description

Technical Field

[0001] The present invention relates to an anode-side half-cell for use in an electrochemical cell of an electrolysis device for carbon dioxide electrolysis and / or carbon monoxide electrolysis. Furthermore, the present invention relates to an electrochemical cell of an electrolysis device for carbon dioxide electrolysis and / or carbon monoxide electrolysis, comprising a cathode region and an anode region separated from the cathode region by a separator, the cathode region having an electrical cathode port, a gas diffusion electrode, a first feed port for supplying carbon dioxide, and a first discharge port for discharging electrolysis substances at least partially generated during normal operation of the electrochemical cell; and an anode region having an electrical anode port, an anode plate, a second feed port for supplying a proton donor substance, and a second discharge port for discharging electrolysis residues at least partially generated during normal operation of the electrochemical cell. The cathode port and the anode port are electrically coupled to corresponding electrical ports for supplying an electrolysis voltage. Furthermore, the present invention relates to an electrolysis device for carbon dioxide electrolysis and / or carbon monoxide electrolysis. Finally, the invention also relates to a method for producing an anode-side half-cell for an electrochemical cell of an electrolysis device for the electrolysis of carbon dioxide and / or for the electrolysis of carbon monoxide. Background Art

[0002] Anode-side cells, electrochemical cells, electrolysis devices for the electrolysis of carbon dioxide and / or carbon monoxide, and methods for producing anode-side cells are generally known in the prior art and therefore require no specific documentation. The electrochemical cells and electrolysis devices constructed therefrom serve to at least partially convert carbon dioxide into carbon monoxide and / or other hydrocarbons. Carbon monoxide may also be used alternatively or additionally to carbon dioxide to at least partially produce other hydrocarbons.

[0003] Carbon dioxide is a substance that is generated when using fossil fuels, in particular, and released into the atmosphere in large quantities. Carbon dioxide is a greenhouse gas and is therefore an undesirable substance in the atmosphere. The problem addressed by the present invention is to make carbon dioxide usable in a wide range of chemical industries. In contrast, carbon monoxide is a raw material for the chemical industry and can be used to produce a large number of chemical products. By producing carbon monoxide from carbon dioxide, this goal can be improved, if not achieved. In addition, other hydrocarbons such as methane, alcohols and / or the like can also be produced in the electrolysis of carbon dioxide. These other substances can also be obtained by electrolyzing carbon monoxide.

[0004] Practice has shown that the production of carbon monoxide or other hydrocarbons from carbon dioxide or carbon monoxide not only requires large consumption, but also has problems. For example, for the electrolysis of carbon dioxide, carbon dioxide needs to be at least partially converted into carbon monoxide by reduction. For this purpose, it is necessary to provide an environment suitable for reduction and a substance that allows carbon dioxide reduction by self-oxidation. Therefore, in many applications, ion-conducting solutions or water-based electrolytes are usually used in electrochemical cells. In the anode side area of ​​the electrochemical cell, the ion-conducting solution or water-based electrolyte is decomposed, thereby being able to provide protons and release oxygen. Here, the water in the ion-conducting solution or the water in the water-based electrolyte acts as a proton donor. This part of the reaction usually occurs at the anode or the anodic region.

[0005] After passing through a suitable separator, preferably one that is permeable only to protons, the protons can be used in the cathode region of the electrochemical cell to reduce carbon dioxide. The carbon dioxide is then at least partially decomposed by reactions in the cathode region, thereby producing carbon monoxide. Furthermore, the released oxygen can, for example, form water together with the protons.

[0006] An electrochemical cell typically has at least one cathode region and an anode region, the anode region being separated from the cathode region by a separator. To carry out an electrochemical reaction in the electrochemical cell, an anode is arranged in the anode region and a cathode is arranged in the cathode region, and a suitable potential is applied to the anode and cathode. In addition, a catalyst is arranged at least in the anode region to support or enable the desired reaction in the anode region.

[0007] In order to carry out the desired chemical reaction in the electrochemical cell, the desired substance can be present at least partially in liquid form or at least partially in gaseous form. If at least the carbon dioxide is supplied in gaseous form, the cathode can comprise, for example, a gas diffusion electrode. This gas diffusion electrode allows solid, liquid, and gaseous substances to come into contact with one another, thereby enabling the desired electrochemical reaction. Gas diffusion electrodes are known, for example, from European Patent Application No. 19 182 017.4.

[0008] The reaction in the electrochemical cell preferably uses an electrolyte. This electrolyte can be formed, for example, from a salt solution, which is preferably aqueous. If a salt solution is used as the electrolyte, the electrolyte on the anode side and the cathode side can be the same. Therefore, the electrolyte can be provided by a single container. Such an electrolyte is sometimes also referred to as a single electrolyte. In addition, it is of course also possible to use different electrolytes in the anode region and the cathode region, wherein the cathode region has a catholyte and the anode region has an anolyte. In the anode region, the anolyte can be formed from water, while in the cathode region, the catholyte can be a catholyte formed in the form of a salt solution. In addition, other electrolyte configurations are conceivable.

[0009] For this type of electrolyzer, achieving a uniform current density distribution across the provided reaction surfaces, particularly at the anode, in order to achieve a good electrochemical cell effect has proven problematic. In particular, substances that simultaneously serve as catalysts and are required to provide electrical conductivity have proven problematic. Furthermore, arranging the various components in predetermined positions and connecting them in a predetermined manner has proven problematic, particularly on the anode side. This leads to costly assembly and design. Reliability suffers both during the manufacture of the electrochemical cell and during normal operation.

[0010] Similar problems may arise in the electrolysis of carbon monoxide. Summary of the Invention

[0011] The object of the present invention is to improve such an anode-side half-cell, an electrochemical cell, such an electrolysis device and a method for producing the same, so that the homogeneity of the current density in the region of the anode is increased and the production and design of electrochemical cells, in particular anode-side half-cells, can be improved.

[0012] As a solution, the present invention proposes an anode-side half-cell, an electrochemical cell, an electrolysis device and a method for producing the same according to the independent claims.

[0013] Advantageous developments are defined by the features of the dependent claims.

[0014] Regarding such an anode-side half-cell, it is particularly proposed that the anode-side half-cell has a separator constructed as a membrane, a catalyst layer and an anode plate permeable to fluid, wherein the separator has an anode-side separator surface and a cathode-side separator surface opposite to the anode-side separator surface; the catalyst layer has a first catalyst surface and a second catalyst surface opposite to the first catalyst surface, wherein the first catalyst surface faces the anode-side separator surface; and the anode plate has a first anode surface, wherein the first anode surface faces the second catalyst surface.

[0015] Furthermore, it is proposed in particular with respect to this electrochemical cell that the anode region and the separator form an anode-side half-cell according to the invention.

[0016] With regard to such an electrolysis device, it is particularly proposed that the electrochemical cells according to the invention be configured such that the electrochemical cells are arranged directly adjacent to one another in space.

[0017] Regarding this method, the present invention particularly proposes that the method has the following steps:

[0018] - arranging an anode-side separator surface of a separator configured as a membrane on a first catalyst surface of a catalyst layer, the separator having a cathode-side separator surface opposite to the anode-side separator surface, the catalyst layer having a second catalyst surface opposite to the first catalyst surface, and

[0019] - arranging the first anode surface of the fluid permeable anode plate on the second catalyst surface.

[0020] The modular design of the electrochemical cell is one of the concepts of the present invention, which not only improves the effectiveness, but also improves the reliability and manufacturing technology. In addition, a modular structure can be achieved, which allows for improved electrical coupling related to the electrical anode port on the anode side, thereby achieving an overall improvement in the homogeneity of the current density at the anode. In summary, the present invention can, on the one hand, simplify assembly and simultaneously improve reliability during assembly, and on the other hand, improve efficiency, in particular Faraday efficiency, and reliability during normal operation. In this way, the efficiency of carbon dioxide electrolysis can also be improved overall.

[0021] The anode-side half-cell is preferably a structural unit that forms part of the electrochemical cell's structure, particularly its modular structure. The anode-side half-cell is preferably a separately handled component. It provides the anode space and separator and can therefore be easily connected to other components or parts of the electrochemical cell. The design of the anode-side half-cell allows for the production of a fully tested structural unit for the electrochemical cell, thereby simplifying installation overall. Furthermore, it improves reliability during installation. At least the anode-side half-cell preferably has a stacked structure. In particular, the components of the anode-side half-cell are arranged one behind the other. The stack can be at least partially secured by mechanical connecting elements. This connection can be detachable or non-detachable. Furthermore, the anode-side half-cell can have its own housing or housing portion. This housing or housing portion can at least partially serve as a connecting element. Fasteners, clamps, screws, rivets, and / or the like can also be used as connecting elements. Adhesives, solder, and / or the like can also be used as connecting elements. Of course, these design features can also be provided for a cathode-side half-cell or an electrochemical cell having an anode-side half-cell and a cathode-side half-cell.

[0022] Preferably, a cathode-side half-cell can also be provided, which includes corresponding elements of the cathode space. To complete the electrochemical cell, at a minimum, only two elements, the anode-side half-cell and the cathode-side half-cell, need to be arranged in combination to form the electrochemical cell. However, additional elements may also be provided depending on the design and requirements.

[0023] In particular, it is of course possible to provide 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, it can also be provided, at least on the cathode side, that some elements or components of the anode-side half-cell are arranged in a predetermined manner as individually handleable elements. These elements can then be connected to one another via mechanical connecting elements to achieve or secure the desired arrangement. The connecting elements can be, for example, locking rings, threaded connections, clip-on connections, and / or the like.

[0024] The electrochemical cell is provided with a reaction zone that allows the carbon dioxide, which is 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 via a solvent. At the same time, the solvent can form the electrolyte of the electrochemical cell, at least the catholyte.

[0025] The electrochemical cell may have, for example, an electrical cathode port in the cathode region, which allows for an electrical connection to be established with a power source, which allows a cathode potential to be applied to the cathode port. The cathode potential is different from the anode potential and is preferably selected to enable the desired electrochemical reaction. The potential difference between the anode potential and the cathode potential is, for example, about 7 V, preferably less than about 7 V, particularly preferably 5 V or less, in particular about 3.8 V.

[0026] The cathode region also includes a gas diffusion electrode, a first feed port for inputting carbon dioxide, particularly in the form of gas, and a first discharge port for discharging an electrolytic substance formed at least in part in the normal operation of the electrochemical cell. The electrolytic substance especially includes the carbon monoxide produced by conventional electrolysis, which is also preferably present as a gas. In addition, the electrolytic substance can also include unconverted carbon dioxide residues in the normal operation of the electrochemical cell. Finally, other substances can exist as electrolytic substances, such as water, particularly in the form of water vapor, hydrogen and / or the like. As needed, the electrolytic substances can be separated from each other by a separation process, so that the carbon monoxide produced by the normal operation of the electrochemical cell can be separated from other substances.

[0027] The separator is preferably a proton-permeable separator. The separator is preferably permeable only to protons and is formed, for example, from a material such as Nafion or the like. The separator can also comprise, for example, an ion-conducting membrane, a porous material that allows the passage of liquids, such as a glass frit or a porous material on a support grid, a polymer-bound porous material, and / or the like, wherein the aforementioned materials can also serve as a support, for example. The separator can be formed as a thin foil or layer, in particular in the form of a membrane. Furthermore, the separator can also be integrally formed with at least one adjacent element of the electrochemical cell, in particular with the catalyst layer.

[0028] The catalyst layer is a layer extending at least partially parallel to the separator. Preferably, the catalyst layer and the separator surface on the anode side are connected to each other and form an integral unit. The catalyst layer comprises a suitable substance that allows protons to be released from the proton donor substance delivered to the anode region through the second feed port, and can be transported to the cathode region through the separator. The proton donor substance can be, for example, water, a salt solution and / or the like. The anode region can also have a second discharge port for discharging electrolysis residues at least partially formed during conventional operation of the electrochemical cell. If the electrolyte or anolyte is formed by water, the residue may include, for example, oxygen, particularly oxygen in the form of gas.

[0029] Furthermore, the anode region can have an electrical anode terminal which, like the cathode terminal of the cathode region, can be electrically coupled to a power source so that an anode potential can be applied to the anode of the anode region.

[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 in particular that the first catalyst surface and the anode-side separator surface are arranged opposite each other. Preferably, these surfaces can be in contact. Particularly preferably, the two surfaces are connected to each other, in particular firmly connected to each other, so that they can form an integral structural unit, for example. In particular, the catalyst layer can be arranged on the anode-side separator surface, depending on the type of coating. This can improve the production of electrochemical cells and half-cells on the anode side and can increase reliability in normal operation.

[0031] The half-cell on the anode side further comprises a fluid-permeable anode plate having a first anode surface and a second anode surface opposite the first anode surface. The first anode surface faces the second catalyst surface. Here, the two surfaces can also be arranged opposite each other. Preferably, the two surfaces are connected to each other, for example, firmly connected to each other. The anode plate is preferably made of a material with good electrical conductivity, such as titanium, a titanium alloy or the like. In addition, the anode plate preferably allows the electrolyte, in particular the anolyte, to be transported to the catalyst surface, more precisely to the second catalyst surface. The anolyte and the catholyte can be liquid and / or gaseous. In addition, the structure of the anode plate also makes it possible to discharge electrolysis residues from the area of ​​the second catalyst surface. As a result, long-term normal operation of the electrochemical cell can be achieved.

[0032] The anode plate preferably 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 is adapted to be electrically connected to a power source that provides the anode potential. The contact plate can be used to reduce, if not completely avoid, voltage gradients during normal operation of the electrochemical cell.

[0033] The contact plate is arranged on the second anode surface and preferably contacts the second anode surface not only mechanically but also electrically. At least the anode plate or the contact plate is used to electrically connect to the power supply. The contact plate is preferably also made of a material with good electrical conductivity. Preferably, the contact plate is formed of titanium or a titanium alloy. However, in addition, the contact plate may also have an additional structure with good electrical conductivity, for example, made of other materials with good electrical conductivity, such as silver, silver alloy, copper, copper alloy and / or the like. This design can improve the uniform distribution of the anode potential on the second anode surface, and thereby also improve the uniform distribution of the anode potential on the first anode surface, wherein the influence caused by different current densities on the anode surface can be reduced. This allows for better homogenization of the function of the electrochemical cell on the available surface, thereby improving efficiency as a whole.

[0034] The contact plate can be constructed as a rigid plate and preferably has the same dimensions as the anode plate. At least with respect to the first and second anode surfaces, the anode plate has dimensions preferably adapted to the second catalyst surface in order to enable high performance.

[0035] The cathode port and the anode port of the electrochemical cell are preferably configured to be electrically coupled to corresponding electrical ports of an energy source that provides the electrolysis voltage. For this purpose, corresponding electrical ports can be provided that allow electrical contact in a conventional manner, such as plug-in ports, threaded ports, welded ports, and / or the like.

[0036] Regarding the electrolysis device, it is further proposed to arrange the electrochemical cells directly adjacent to each other in space. This makes it possible to achieve a compact structure of the electrolysis device as a whole, wherein, at the same time, a simple connection of the electrochemical cells can also be achieved. In particular, the first feed port and the second feed port as well as the first discharge port and the second discharge port can be connected in parallel in a flow-technical manner, so that the required substances can be supplied to the electrochemical cell in a substantially uniform manner and the corresponding products can be discharged by the normal operation of the electrochemical cell at the same time. In addition, the electrical interconnection of the electrochemical cells for normal operation can be achieved in a simple manner. The electrochemical cells can be connected in series and / or in parallel at least in part.

[0037] From a process technology perspective, it can be provided that the separator surface on the anode side is arranged on the first catalyst surface. This can be achieved, for example, by coating the separator surface on the anode side with a catalyst. In this way, a reliable and strong connection between the separator and the catalyst can be achieved. The second catalyst surface can then be connected to the first anode surface, for example by means of a conductive adhesive or the like. However, in principle, it can also be provided that the first anode surface is prestressed relative to the second catalyst surface by force so that corresponding contact can be achieved. It can also be provided that a first layer made of catalyst material is applied to the first anode surface of the anode plate. The first layer made of catalyst material thus formed can be connected to the first anode surface in the form of a covering layer. A second layer made of separator material can be applied to this layer made of catalyst material. This second layer made of separator material is preferably also connected to the first layer made of catalyst material in the form of a covering layer. In this way, a structural unit of an integral structure can be provided in a simple manner. Of course, combinations of the above-mentioned embodiments can also be provided.

[0038] In addition, the contact plate can be arranged on the second anode surface so that good electrical contact can be achieved between the anode plate and the contact plate. As a result, the anode potential can be constructed essentially homogeneously, preferably uniformly, on the anode plate, so that the anode potential can also be provided as homogeneously as possible on the second catalyst surface. At least the anode plate or the contact plate is used to be electrically connected to the power supply, and for this purpose corresponding port facilities can be provided, which allow a reliable conductive connection to be established with the power supply. For this purpose, a separate port facility can be provided that is in contact with the anode plate and / or the contact plate. In this way, a simple production method can be achieved, which is also very suitable for mass production, in particular automated mass production. As a result, reliability can be achieved not only in the production of electrochemical cells, in particular half-cells on the anode side, but also in conventional operation, because the production method allows production conditions that are as homogeneous as possible to be ensured.

[0039] It is further suggested that the catalyst layer at least partially comprise iridium (IV) oxide. This material is particularly suitable for use as a catalyst for carbon dioxide electrolysis. Of course, iridium (IV) oxide can also be mixed with other substances that further improve the catalyst function or at least improve the mechanical properties of the catalyst layer. In addition, other metal oxides can also be provided. Combinations of these substances are also possible.

[0040] According to a further development, it is proposed that at least the anode plate or the contact plate comprise titanium and / or a titanium alloy. It has been shown that titanium is particularly advantageous in the anode region for CO2 electrolysis. Furthermore, titanium provides good electrical conductivity, thereby enabling the anode potential to be generated as uniformly as possible over the surface of the anode plate.

[0041] According to another advantageous design, it is proposed that the anode plate be constructed to be at least partially porous. The porous construction of the anode plate makes it possible to simply feed the fluid anolyte or the proton donor substance into the region of the catalyst or the catalyst layer. The porosity can be generated using known methods. Furthermore, it can of course be provided that the anode plate has supplementary through-holes that lead to the corresponding opposite anode surfaces. Depending on the design, these through-holes can be distributed evenly or asymmetrically over the extension of the anode surface. The porosity can be selected in a suitable manner depending on the viscosity and / or other physical properties of the anolyte and / or the proton donor substance, such as temperature or the like.

[0042] It is further suggested that the first anode surface is connected to the second catalyst surface by a conductive connection technology. The conductive connection technology makes it possible to firmly connect the first anode surface to the second catalyst surface, thereby being able to form a structural unit that is particularly integral. At the same time, a good conductive connection can be achieved between the first anode surface and the second catalyst surface, preferably on a contact surface that is as large as possible. This allows, if the potential gradient cannot be substantially completely suppressed in the conventional operation of the electrochemical cell, to further reduce the potential gradient relative to the anode potential. The conductive connection technology can be achieved, for example, by welding, gluing, brazing, combinations thereof and / or similar methods. With the help of the conductive connection technology, a conductive connection can be achieved at multiple points and / or in a surface manner, for example, on the entire contact surface or a pre-specified partial area of ​​the contact surface.

[0043] The connection technology preferably uses a conductive adhesive. In this way, the first anode surface can be connected to the second catalyst surface via the conductive adhesive. In this way, a strong connection between the first anode surface and the second catalyst surface can be achieved in a simple and reliable manner, thereby enabling a strong bond that can be handled separately. In addition, the performance of the bond can be tested separately. This makes it possible to improve reliability. For example, a conductive adhesive can be used as an adhesive, which is based on, for example, 1-20% by mass of polytetrafluoroethylene (PTFE), 1-20% by mass of polyvinylidene fluoride (PVDF) or the like. In addition, an adhesive based on epoxy resin or cyanoacrylate can also be used.

[0044] The binder preferably comprises particles composed of iridium (IV) oxide. This allows for a particularly favorable transition between the binder and the catalyst. The binder therefore does not have to adversely affect the effectiveness of the catalyst. On the contrary, the binder can further support the effectiveness of the catalyst.

[0045] The adhesive can be arranged over the entire surface between the first anode surface and the second catalyst surface. However, it is also possible to arrange the adhesive only partially between the two surfaces, for example, in a predefined pattern or the like. This can minimize the adhesive requirement while achieving a reliable, good connection between the surfaces.

[0046] It is further proposed that the second catalyst surface has a projection protruding from it, which, for connection to the anode plate, extends through the first anode surface into the anode plate. This allows for a further improved connection between the second catalyst surface and the first anode surface. In particular, a transition region can be created on the anode plate side in the region of the first anode surface, i.e., by already having catalyst material present, thereby further improving the catalytic function. Overall, this can also improve the efficiency of the anode-side half-cell, and thus the efficiency of the electrochemical cell.

[0047] Furthermore, it is recommended that the protrusions be formed from the same material as the catalyst layer, thereby achieving not only a good connection but also improving the function of the catalyst.

[0048] The projections can be designed to press into the anode plate and in this way improve the firm connection between the first anode surface and the second catalyst surface. In particular, this allows for better absorption of warping effects between the two surfaces.

[0049] It is further proposed that the projections are formed by pins arranged spaced apart from one another, and that the anode plate, in particular the first anode surface, has a receiving opening for accommodating the pins. In this way, the anode plate can be coupled to the catalyst layer at least mechanically, but preferably also electrically, in the form of a plug-in connection. For this purpose, the receiving opening can be configured to adapt to the mechanical dimensions of the pin so that an electrical connection is achieved in addition to the mechanical connection. This can further improve the homogeneity of the anode potential in the region of the catalyst layer. The plug-in connection can be configured in the form of a pin grid array (PGA), in which the contacts of the receiving opening and the pins are arranged in a predetermined grid. The contacts can also be arranged in the form of a staggered pin grid array (SPGA), in which the contacts in adjacent rows are arranged staggered with respect to one another. In order to produce the plug-in connection, the pins can be configured relative to the receiving opening so that a predetermined force is required to insert them. The connection can preferably be configured in the form of a low insertion force (LIF) connection. In addition, the connection can be configured in the form of a zero insertion force (ZIF) connection, in which the connection can be achieved essentially without force. For this purpose, provision can be made for a clamping device to provide a clamping connection between the pin and the receiving opening in the inserted state. This clamping connection can be actuated by a preferably manually actuated drive element, thereby enabling switching between a locked state and an unlocked state. This not only enables a secure connection but also allows it to be released again.

[0050] According to an improved solution, it is recommended that the contact plate have a contact plate surface opposite the second anode surface, and that the contact plate surface have at least a connecting element for mechanically connecting the contact plate surface to the second anode surface. In this way, the contact plate can be mechanically and firmly connected to the second anode surface. In addition, there is the possibility of simultaneously establishing a good electrical connection between the second anode surface and the contact plate. This connection can further improve the homogeneity of the anode potential of the anode plate. The contact plate is preferably also made of a material with good electrical conductivity, which can be selected as the material of the anode plate in an appropriate manner. For example, the contact plate can also be made of titanium or a titanium alloy. The contact plate can also at least partially have a port area, which can be formed of a highly conductive material such as silver, a silver alloy, copper, a copper alloy, and / or the like. In addition, the contact plate can also have a corresponding conductor pattern on its planar extension, which further improves the electrical conductivity of the contact plate as a whole and thus further supports the homogeneity of the anode potential.

[0051] Preferably, the connecting element and the contact plate are electrically conductive. The connecting element can, for example, be made of the same material as the contact plate. The connecting element can, for example, be formed by a projection on the contact plate. The projection can be configured 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, which can reduce, if not substantially avoid, the anode potential gradient across the planar extent of the anode plate. The connecting element can be connected to the second anode surface by force. Furthermore, the connecting element and the second anode surface can also be welded or soldered.

[0052] Furthermore, it is recommended that the connecting element and / or the projection be formed by pins arranged at a distance from one another. The pins can be configured in the manner of a grid on the contact plate surface. The pins preferably have a diameter that is smaller than the thickness of the contact plate. The pins can have a circular or angular cross-section in their longitudinal extent. The pins are preferably configured to establish good electrical contact with the second anode surface and the anode plate on the anode side. For this purpose, the axial ends can be configured with spikes or hemispherical shapes.

[0053] Regarding electrochemical cells, it is further suggested that the elements of the cathode and anode regions be arranged in a stack. By arranging the elements of the cathode and anode regions alternately, a modular layer structure can be achieved, which is particularly advantageous in terms of manufacturing. In addition, the stack formed in this way can be mechanically stabilized in a simple manner, so that the electrochemical cells consisting of the components can be handled individually. In addition, the electrochemical cells can also be tested individually. This design is particularly conducive to the automated production of electrochemical cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The embodiments explained below are preferred embodiments of the present invention. The features and feature combinations given above in the specification and the features and feature combinations mentioned in the following description of the embodiments and / or shown separately in the drawings can be used not only in the respective given combinations, but also in other combinations. Therefore, the present invention also includes or is deemed to disclose embodiments that are not explicitly shown and explained in the drawings, but that appear or can be produced by individual feature combinations from the explained embodiments. The features, functions and / or utilities shown in the embodiments themselves can each show the individual features, functions and / or utilities of the present invention to be considered independently of each other, and these features, functions and / or utilities should also further develop the present invention independently of each other. Therefore, the embodiments should also include combinations other than the combinations in the explained embodiments. In addition, the described embodiments can also be supplemented by other features, functions and / or utilities described in the present invention.

[0055] Figure 1A schematic functional block diagram of an electrolysis apparatus for electrolysis of carbon dioxide having a plurality of electrochemical cells electrically connected in series;

[0056] Figure 2 according to Figure 1 A schematic cross-sectional view of an electrochemical cell of an electrolysis device;

[0057] Figure 3 In the first design, according to Figure 2 A schematic cross-sectional view of an anode side half-cell of an electrochemical cell;

[0058] Figure 4 In the second design, Figure 3 A schematic cross-sectional view of

[0059] Figure 5 In the third design scheme, Figure 3 A schematic cross-sectional view of

[0060] Figure 6 Figure 5 Schematic enlarged view of region VI;

[0061] Figure 7 The fourth design scheme is based on Figure 3 A schematic cross-sectional view of

[0062] Figure 8 In accordance with Figure 7 A schematic perspective view of a catalyst surface with projections configured in the form of pins in a design of ;

[0063] Figure 9 Figure 8 A magnified view of region IX; and

[0064] Figure 10 Used according to Figure 8 Schematic top view of the first anode surface of the anode plate connected to the catalyst layer. DETAILED DESCRIPTION

[0065] Figure 1 The electrolysis device 12 for electrolysis of carbon dioxide is shown in a schematic functional block diagram. In normal operation of the electrolysis device, carbon monoxide is at least partially produced from carbon dioxide. The electrolysis device 12 includes a plurality of electrochemical cells 10 in which carbon dioxide electrolysis occurs. Two of the electrochemical cells are in Figure 1 In the present embodiment, it is provided that the electrochemical cells 10 are electrically connected in series, wherein the series circuit is connected to the power supply 36 via an electrical line 82 in order to apply a potential to the electrochemical cells 10 in a corresponding manner at the individual electrodes, as will be explained below.

[0066] 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 port 16, a gas diffusion electrode 18, a first feed port 20 for feeding carbon dioxide, which is electrically coupled to the cathode port 16, and a first discharge port 22 for discharging electrolytic substances at least partially formed during normal operation of the electrochemical cell 10, which in particular include carbon monoxide. In addition, the electrolytic substances may of course also contain carbon dioxide residues that have not been converted in the electrochemical cell 10. In addition, other residues are also possible. In addition, the cathode region 14 is connected to a line 30 for feeding and discharging a catholyte, here a salt solution.

[0067] The anode region 26 comprises an electrical anode port 28 , an anode plate 50 , a second feed port 32 for supplying a proton-donating substance, which is electrically coupled to the electrical anode port 28 , and a second discharge port 34 for discharging electrolysis residues at least partially formed during normal operation of the electrochemical cell 10 .

[0068] The cathode port 16 and the anode port 28 are designed to be electrically coupled to a suitable or corresponding electrolysis voltage of a power supply 36. The respective first feed port 20 and second feed port 32 as well as the respective first discharge port 22 and second discharge port 34 are each fluidically connected in parallel so that, during normal operation, the electrochemical cell 10 can be supplied with the corresponding substances from the corresponding sources.

[0069] Figure 2 The schematic cross-sectional view shows Figure 1 One of the electrochemical cells 10. For clarity, the feed ports 20, 32 and the discharge ports 22, 34 are not shown.

[0070] Figure 2 One of the electrochemical cells 10 is shown in a sectional view. As can be seen, the electrochemical cell 10 has a stacked structure. The cathode region 14 comprises a cathode electrolyte element 74, which adjoins a gas diffusion electrode 18, which in the present case at least partially represents the cathode. The gas diffusion electrode 18 is also adjacent to a contact frame 76, which in the present case is formed from silver or a silver alloy. The contact frame 76 adjoins a gas separator element 78, which serves in particular for the supply of carbon dioxide and the discharge of carbon monoxide. The gas separator element 78 adjoins a window 80, with which the cathode region 14 is closed. In alternative designs, end plates or the like can also be provided instead of the window 80 or in addition to it.

[0071] Catholyte element 74 also abuts separator 24, more specifically, cathode-side separator surface 42. Separator 24 has an anode-side separator surface opposite this cathode-side separator surface. Separator 24 is currently formed from a proton-permeable material. In the current design, Nafion is used as the material for separator 24. Other suitable materials may also be used in alternative designs.

[0072] The structure and function of the gas diffusion electrode 18 are known, for example, from European Patent Application 19 182 017.4. Reference is therefore made to the relevant publication in this respect.

[0073] In the present embodiment, the anode region 26 is formed as a structural unit together with the separator 24. This allows the creation of individually processable units that simplify the production of the electrochemical cell 10 and improve reliability both during production and during normal operation.

[0074] For this purpose, in the anode region 26, it is provided that the separator 24 is provided with a catalyst layer 44 in the manner of a membrane electrode assembly (MEA). For this purpose, the separator 24 is also constructed as a membrane. The separator 24 has an anode-side separator surface 40 and a cathode-side separator surface 42 opposite the anode-side separator surface 40. In addition, 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 current design, it is provided that the first catalyst surface 46 is firmly 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 form of a coating. In this way, a reliable and firm connection between the catalyst layer 44 and the separator 24 is achieved.

[0075] The anode region 26 further comprises a fluid-permeable anode plate 50 having 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 design, it is provided that the first anode surface 52 is connected to the second catalyst surface 48. As will be explained below, this connection can be achieved in different ways, in particular according to the different embodiments discussed below.

[0076] In the present case, the anode plate 50 is designed to be porous in order to enable the desired permeability for gases or also for liquids such as water or the like.

[0077] The contact plate 56 is arranged on the second anode surface 54. To this end, the contact plate 56 has a contact plate surface 68 connected to the second anode surface 54. The contact plate 56 is electrically coupled to the electrical anode port 28. An end plate 72 is arranged on the surface of the contact plate 56 opposite the contact plate surface 68 and closes the anode region 26 to the outside.

[0078] Separator 24, catalyst layer 44, and anode plate 50 form an anode-side half-cell 38 as a structural unit. Depending on the design and requirements, the structural unit may further include a contact plate 56. Anode-side half-cell 38, and in particular, its structure, will be explained in more detail with reference to other embodiments described below.

[0079] Currently, the catalyst layer 44 is primarily formed from iridium (IV) oxide. However, in principle, other metal oxides or mixtures thereof can also be used, depending on the desired properties.

[0080] Currently, the anode plate 50 and the contact plate 56 are formed from a titanium alloy. This allows for good electrical conductivity, so that the anode potential is formed as evenly or homogeneously as possible across the anode surfaces 52, 54. This promotes the efficiency of the electrolysis process in the electrochemical cell 10.

[0081] Either water or a salt solution can be used as the anolyte, which also provides a proton donor substance, thereby being able to provide protons for the desired electrochemical reaction of carbon dioxide electrolysis.

[0082] At the anode, the chemical reaction can be realized according to the following equation:

[0083] 2H20(l)+4OH-→O2(g)+4e-+4H2O(l)

[0084] At the cathode, the main reaction occurs according to the following chemical equation:

[0085] CO2(g)+H2O(l)+2e-→CO(g)+20H-

[0086] 2H2O(l)+2e-→H2(g)+20H-

[0087] Figure 3 A first embodiment of the anode-side half cell 38 is shown. Figure 3It is obvious that the second catalyst surface 48 is connected to the first anode surface 52 by an adhesive 58. In this design, the adhesive 58 is a gas-permeable adhesive that establishes a material connection between the second catalyst surface 48 and the first anode surface 52. The adhesive can have, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF) and N-methyl-2-pyrrolidone as a solvent. N-methyl-2-pyrrolidone dissolves the above-mentioned two polymers after addition and subsequently forms a strong adhesive layer after evaporation. However, in principle, other adhesion adhesives can also be used, for example, adhesives based on epoxy resins or based on cyanoacrylates.

[0088] The binder 58 is preferably made of the same or similar material as the separator 24. It should be noted that if Nafion, a perfluoropolymer containing sulfone groups as ionic groups, is used as the separator 24 material as currently specified, a similar material should be used as the binder as much as possible, which minimizes the introduction of foreign chemical components into the electrolysis process, thereby ensuring that the electrolysis process remains unaffected. Accordingly, the use of other binders is generally limited to those that do not significantly negatively affect the electrolysis process.

[0089] The second anode surface 54 is mechanically and electrically connected to the contact plate 56 via a connecting element 70. The connecting element 70 can provide a point-like or continuous mechanical and electrical connection, for example, via welded or adhesive points or by soldering or the like, depending on the suitability.

[0090] In the present embodiment, the anode plate 50 is electrically coupled to the power source 36, more precisely to the anode potential of the power source. Via the contact plate 56, a substantially homogeneous anode potential can be set on the porous anode plate 50, even at high current densities, across the anode surfaces 52, 54.

[0091] Figure 4 Shown based on Figure 3 Other designs of the anode side half cell 38 of the design scheme. Figure 3 The design scheme is different. Figure 4 The design scheme of provides that the adhesive 58 is replaced by the adhesive 60. Other structures are in accordance with Figure 3 Example of .

[0092] The adhesive 60 can be constructed essentially like the adhesive 58, but further comprises fibers made of iridium (IV) oxide. This can further improve the functionality, in particular with regard to the catalytic effect. Furthermore, the structure of the half-cell 38 on the anode side conforms to the already described Figure 3Specifically, adhesive 60 has a higher electrical conductivity than adhesive 58 .

[0093] Figure 5 Shown based on Figure 4 For further embodiments of the anode-side half-cell 38 of the embodiment of FIG. 1 , please refer to the related exemplary embodiments in addition.

[0094] In accordance with Figure 5 In the embodiment of the invention, iridium (IV) oxide fibers or separator strips coated with iridium (IV) oxide or, if appropriate, other plastic or metal fibers or metal strips are already applied to one side of the separator 24 during the production of the separator 24, more precisely to the separator surface 40 on the anode side. In a subsequent production step, the separator 24, which already contains the catalyst layer 44, is connected to the first anode surface 52 of the anode plate 50. This connection can be referred to Figure 3 and Figure 4 In this way, the catalyst layer 44 can be connected to the separator 24 in a more mechanically stable manner.

[0095] The adhesives 58 , 60 between the catalyst layer 44 and the anode plate 50 may be arranged over the entire surface or in spots, respectively, depending on the application. Figure 6 Shown Figure 5 Zoomed in screenshot of area VI.

[0096] Figure 7 A further embodiment of the anode-side half cell 38 is shown, which is based in principle on the Figures 3 to 6 Therefore, please refer to the relevant embodiments for supplementary reference. Figures 3 to 6 The design scheme is different. Figure 7 In the embodiment of the present invention, no adhesive is provided. Instead, the second catalyst surface 48 of the catalyst layer 44 has a projection 62 made of catalyst material, which extends through the first anode surface 52 into the anode plate 50. This embodiment also provides for the power source 36 to be electrically coupled to the contact plate 56. This ensures both a good electrical and mechanical connection and good efficiency in the electrolysis of carbon dioxide in accordance with the arrangement.

[0097] Figures 8 to 10 Shown based on Figure 7 From Figures 8 to 10It is obvious that the membrane structure composed of the separator 24 and the catalyst layer 44 can be connected to the anode plate 50 in an insertable manner. In this way, not only a simple assembly can be achieved, but also detachability can be achieved, which allows the anode plate 50 to be separated from the membrane structure composed of the separator 24 and the catalyst layer 44 as needed. For this purpose, according to Figure 7 The design solution provides that the catalyst layer 44 provides the protrusion 62 as a pin 66. The protrusion extends from the second catalyst surface 48 ( Figure 8 )protrude. Figure 9 Shown Figure 8 A magnified screenshot of area IX.

[0098] Figure 10 The anode plate 50 is shown in a schematic top view on the first anode surface 52. It can be seen that the anode plate 50 is shown in a schematic top view on the first anode surface 52. Figure 8 The arrangement of the pins 66 of the catalyst layer 44 provides a receiving opening 64. When the catalyst layer 44 is connected to the anode plate 50, the pins 66 are introduced into the receiving opening 64. This enables a reliable mechanical and electrical connection between the anode plate 50 and the catalyst layer 44.

[0099] Advantageously, provision can be made for the connection to be detachable. This can be achieved by a corresponding separation force, so that the anode plate 50 can ultimately be easily removed from the catalyst layer 44. However, in principle, a substantially forceless connection can also be provided by the anode plate 50 comprising a locking element that allows, in a first locking state, the pin 66 to be introduced into the receiving opening 64 with virtually no force and, in a second locking state, secures the pin 66 in the receiving opening 64. In this way, a simple, detachable mounting can be simultaneously achieved.

[0100] In summary, the present invention makes it possible to significantly simplify the structure of the electrochemical cell 10 and the electrolysis device 12. Furthermore, the reliability can be improved. For example, potassium bicarbonate, potassium sulfate, or the like can be used as the catholyte.

[0101] With the anode-side half-cell 38 according to the present invention, a Faradaic efficiency in the range of approximately 90% to 100%, preferably approximately 95%, can be achieved. The electrolysis is preferably carried out at a temperature above room temperature. This temperature range can preferably be from approximately 40° C. to approximately 90° C., particularly preferably at approximately 60° C.

[0102] The following advantages can be achieved by the present invention:

[0103] • A strong connection between the contact structures on the anode side is achieved by the composite consisting of catalyst layer and separator.

[0104] Frequent contacting makes it possible to ensure that the anode potential lies essentially uniformly on the surface even at high current densities.

[0105] The structural unit consisting of separator and catalyst layer is significantly less prone to swelling or expansion and thus less prone to protruding from the contact portion (buckling).

[0106] The catalyst-coated coating of the separator can be protected from mechanical wear and tear during other handling in the manufacturing field or during normal operation.

[0107] ·No high force is required for contact.

[0108] Enables better handling and simplified installation in production.

[0109] The aforementioned embodiments are merely intended to illustrate the present invention and should not limit the present invention.

Claims

1. A half-cell (38) on the anode side of an electrochemical cell (10) for an electrolysis device (12) for carbon dioxide electrolysis and / or carbon monoxide electrolysis, the half-cell on the anode side comprising: a separator (24) configured as a membrane, the separator having an anode-side separator surface (40) and a cathode-side separator surface (42) opposite the anode-side separator surface (40); - a catalyst layer (44) having a first catalyst surface (46) and a second catalyst surface (48) opposite the first catalyst surface (46), wherein The first catalyst surface (46) faces the separator surface (40) on the anode side; as well as - a fluid-permeable anode plate (50) having a first anode surface (52), wherein the first anode surface (52) faces the second catalyst surface (48), - the second catalyst surface (48) has a projection (62) protruding from the surface, the projection extending through the first anode surface (52) into the anode plate (50) for connection to the anode plate (50), the projection (62) being formed by pins (66) arranged at a distance from one another, and the anode plate (50) having a receiving opening (64) for receiving the pins (66).

2. The anode-side half-cell according to claim 1, characterized in that The anode plate (50) has a second anode surface (54) opposite the first anode surface (52), wherein a contact plate (56) is arranged on the second anode surface (54), and wherein at least the anode plate (50) or the contact plate (56) is adapted to be electrically coupled to a power source (36) that provides an anode potential.

3. The anode-side half-cell according to claim 1 or 2, characterized in that At least the anode plate (50) or the contact plate (56) comprises titanium or a titanium alloy.

4. The anode-side half-cell according to claim 1 or 2, characterized in that The anode plate (50) is at least partially porous.

5. The anode-side half-cell according to claim 1 or 2, characterized in that The first anode surface (52) is connected to the second catalyst surface (48) via a conductive connection technique.

6. The anode-side half-cell according to claim 5, characterized in that The connection technology uses an electrically conductive adhesive (58, 60), wherein the adhesive (60) comprises particles made of iridium (IV) oxide.

7. The anode-side half-cell according to claim 1 or 2, characterized in that The protrusion (62) is formed of the same material as the catalyst layer (44).

8. The anode-side half-cell according to claim 1 or 2, characterized in that The first anode surface (52) has a receiving opening (64) for receiving the pin (66).

9. The anode-side half-cell according to claim 2, characterized in that: The contact plate (56) has a contact plate surface (68) opposite the second anode surface (54), the contact plate surface having a connecting element (70) for at least mechanically connecting the contact plate surface (68) to the second anode surface (54).

10. The anode-side half-cell according to claim 9, characterized in that The connecting element (70) and the contact plate (56) are designed to be electrically conductive.

11. An electrochemical cell (10) for an electrolysis device (12) for the electrolysis of carbon dioxide and / or for the electrolysis of carbon monoxide, the electrochemical cell comprising: a cathode region (14) having an electrical cathode port (16), a gas diffusion electrode (18), a first feed port (20) for feeding carbon dioxide, and a first discharge port (22) for discharging electrolytic substances at least partially formed during normal operation of the electrochemical cell (10); an anode region (26) separated from the cathode region (14) by a separator (24), the anode region having an electrical anode port (28), an anode plate (50), a second feed port (32) for supplying a proton-donating substance, and a second discharge port (34) for discharging electrolysis residues at least partially formed during normal operation of the electrochemical cell (10), -in, The cathode port (16) and the anode port (28) are configured to be electrically coupled to respective electrical ports of a power source (36) that provides an electrolysis voltage. It is characterized in that the anode region (26) and the separator (24) are designed as an anode-side half-cell (38) according to one of the preceding claims.

12. The electrochemical cell according to claim 11, wherein The elements of the cathode region (14) and the anode region (26) are arranged in a stack.

13. An electrolysis device (12) for electrolysis of carbon dioxide and / or for electrolysis of carbon monoxide, characterized in that An electrochemical cell (10) according to claim 11 or 12 is provided, wherein the electrochemical cells (10) are arranged directly adjacent to one another in space.

14. A method for producing an anode-side half-cell (38) for an electrochemical cell (10) of an electrolysis device (12) for the electrolysis of carbon dioxide and / or for the electrolysis of carbon monoxide, comprising the following steps: - arranging an anode-side separator surface (40) of a separator (24) configured as a membrane, the separator having a cathode-side separator surface (42) opposite the anode-side separator surface (40), on a first catalyst surface (46) of a catalyst layer (44), the catalyst layer (44) having a second catalyst surface (48) opposite the first catalyst surface (46); and - arranging a first anode surface (52) of a fluid-permeable anode plate (50) on said second catalyst surface (48), - the second catalyst surface (48) has a projection (62) protruding from the surface, the projection extending through the first anode surface (52) into the anode plate (50) for connection to the anode plate (50), the projection (62) being formed by pins (66) arranged at a distance from one another, and the anode plate (50) having a receiving opening (64) for receiving the pins (66).

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