Electrolytic cell with optimized contact of catalyst layers
By setting up a current bridge and lateral connectors in the CO2 electrolysis cell, the problem of insufficient conductivity of the catalyst layer was solved, achieving uniform voltage distribution and expansion of the catalyst layer area, thus simplifying the manufacturing process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SIEMENS ENERGY GLOBAL GMBH & CO KG
- Filing Date
- 2024-09-16
- Publication Date
- 2026-07-14
Smart Images
Figure CN122396820A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an electrolytic cell for CO2 electrolysis. The electrolytic cell has a gas chamber containing CO2 and a water chamber containing electrolyte, the gas chamber and the water chamber being separated from each other by a gas diffusion layer and a catalyst layer. Here, it is necessary for the catalyst layer to be in contact. Background Technology
[0002] Renewable electricity, such as solar and wind power, can be provided in some locations to a degree exceeding local demand. In such cases, the efficient use of available electricity becomes problematic. One possibility is the electrolysis of water into hydrogen and oxygen. However, the storage and transportation of hydrogen are problematic. Furthermore, it is known to utilize available renewable electricity through the electrochemical conversion of CO2, thereby combining the greenhouse gas CO2 as a product. The electrochemical reduction reaction of carbon dioxide (CO2) into hydrocarbons via CO2 electrolysis represents a highly promising alternative to other energy storage strategies.
[0003] To reduce CO2, an electrolytic cell with an anode side and a cathode side is used. An anode is present on the anode side, and this anode is in contact with a liquid electrolyte. A cathode is present on the cathode side, and this cathode is in contact with the CO2 to be reduced. In a conventionally used electrolytic cell, a chamber for containing CO2 is arranged on the cathode side, and a chamber for containing the electrolyte is arranged on the anode side; these chambers are separated from each other by gas diffusion electrodes.
[0004] The general operating methods of electrolytic cells used for CO2 electrolysis are well known to those skilled in the art. This is described, for example, in WO 2023 217624 A1 or WO 2019 096985 A1.
[0005] It has proven advantageous that the gas diffusion electrode is formed of a non-conductive gas diffusion layer and a conductive catalyst layer. Here, contact with the catalyst layer is required from the cathode side.
[0006] Contact with the catalyst layer typically occurs at the periphery of the catalyst layer, for example, by applying a copper strip. If the expansion of the electrolytic cell is small, a sufficiently uniform voltage distribution can be achieved on the surface of the catalyst layer.
[0007] The problem lies in the limited conductivity of the catalyst layer and the typically small layer thickness used in catalyst layers. Combined with the necessity of providing sufficient catalyst layer area for practical applications, it is not easy to ensure a sufficient, and particularly uniform, voltage between the catalyst layer and the anode.
[0008] To address this problem, a known implementation proposes arranging a conductive mesh, for example a conductive mesh made of copper, on the catalyst layer opposite to the gas diffusion layer, i.e., on the anode side in the electrolyte.
[0009] However, this arrangement has several drawbacks. Firstly, the arrangement of the conductive mesh in the electrolyte can adversely affect the electrochemical process. Secondly, the smaller spacing between the anode and the conductive mesh is disadvantageous relative to the spacing between the anode and the catalyst layer. Furthermore, the effective area of the catalyst layer is reduced by the mesh arrangement. Summary of the Invention
[0010] The objective of this invention is to provide the most uniform voltage possible across the area of the catalyst layer. Here, the effectively usable area of the catalyst layer should be as large as possible.
[0011] This objective is achieved through an embodiment of the invention according to the teachings of claim 1. Advantageous embodiments are the subject of the dependent claims.
[0012] This type of electrolytic cell is specified for use in CO2 electrolysis. The electrolytic cell has a cathode side and an opposing anode side. Starting from the cathode side, in a direct or indirect order, the electrolytic cell comprises:
[0013] - Cathode plate,
[0014] - Air chamber,
[0015] - Gas diffusion layer,
[0016] - Catalyst layer,
[0017] - Water chamber, and
[0018] - Anode plate.
[0019] The cathode plate and the anode plate together form the sealed ends of the electrolytic cell on both sides.
[0020] The gas chamber is a cavity in the electrolytic cell into which CO2 is supplied as specified during operation. The water chamber is a separate cavity into which electrolytes are present as specified during operation.
[0021] The gas diffusion layer, together with the catalyst layer, forms the gas diffusion electrode. This electrode separates the gas chamber from the water chamber. Here, for functional reasons, the gas diffusion layer must be permeable to CO2 but prevent the passage of liquid.
[0022] The gas diffusion layer is, in a particularly advantageous manner, non-conductive. For this purpose, the gas diffusion layer is made of a non-conductive material, or has at least one non-conductive coating.
[0023] In contrast, the catalyst layer is particularly advantageously conductive. Therefore, the catalyst layer is made of a conductive material or has at least one conductive coating.
[0024] Accordingly, the advantageous gas diffusion electrode in this case is formed by a non-conductive gas diffusion layer and a conductive catalyst layer.
[0025] Furthermore, it is feasible for the catalyst layer or gas diffusion layer itself to be composed of multiple layers. For possible and advantageous layer structures, refer to known prior art.
[0026] It is evident that the gas chamber and gas diffusion layer, as well as the catalyst layer and water chamber, must be advantageously sealed around each other to enable the gas chamber and water chamber to function as cavities. It is also evident that appropriate interfaces are needed for introducing fluid into and removing fluid from the gas chamber or water chamber, respectively.
[0027] In a simple and advantageous manner, the gas chamber is directly adjacent to the cathode plate.
[0028] A particularly advantageous feature is that the gas diffusion layer is adjacent to the gas chamber.
[0029] If the catalyst layer is directly adjacent to the gas diffusion layer, efficient CO2 electrolysis can be achieved.
[0030] A particularly advantageous feature is that the water chamber is adjacent to the catalyst layer.
[0031] In a simple and advantageous manner, the water chamber is adjacent to the anode plate.
[0032] Here, the anode plate preferably also forms the anode of the electrolytic cell.
[0033] Depending on the function, it is necessary to be able to apply voltage to the electrolytic cell. Here, it is particularly advantageous that the current to the electrolytic cell is connected on the anode side at the anode plate and on the cathode side at the cathode plate.
[0034] In order to achieve the most uniform voltage distribution at the catalyst layer and reduce the disadvantages caused by the conductive grid on the anode side, it is further specified that multiple current bridges penetrate the gas diffusion layer and establish conductive connections from the catalyst layer directly or indirectly to the cathode plate.
[0035] In this embodiment, the current flow to the catalyst layer is distributed across multiple current bridges, eliminating the need for corresponding transport from the outer edge of the catalyst layer to its surface. Therefore, the necessity of arranging a conductive grid in the water chamber and then in the electrolyte from the edge of the catalyst layer is eliminated. This allows for flexible cell size design and removes limitations on small structural dimensions.
[0036] It is obvious and advantageous that the surrounding edges of the catalyst layer can be electrically contacted without weakening, so that the edge region of the catalyst layer is supplied with voltage.
[0037] If the corresponding current bridge penetrates the catalyst layer, then the contact between the current bridge and the catalyst layer can be optimized. Accordingly, it is further stipulated that at least most of the current bridges penetrate the catalyst layer.
[0038] At least most implementations where the current bridge penetrates the catalyst layer particularly advantageously open up the possibility of arranging a conductive element that partially covers the catalyst layer at the current bridge on the anode side of the catalyst layer. Therefore, further improved contact of the catalyst layer can be achieved through additional elements.
[0039] However, the reduction in effective area due to the additional elements must be taken into account, and accordingly, this should only be chosen to be so large that reliable contact of the catalyst layer can be achieved in the corresponding current bridge.
[0040] According to the present invention, optimized contact is achieved by using lateral connectors that electrically connect at least two current bridges to each other, and at the same time, additional contact of the catalyst layer is caused by abutment on the anode side of the catalyst layer.
[0041] Preferably, the lateral connectors connect two current bridges, although multiple lateral connectors may exist. It is also possible to specify that the lateral connectors connect, for example, three or four current bridges. Furthermore, it is possible to specify that the lateral connectors are connected to multiple current bridges. Important for this invention is that there are connectors between the current bridges on the anode side, which rest against the catalyst layer, while maintaining a small coverage area of the catalyst layer as much as possible.
[0042] To ensure a defined spacing between the cathode plate and the gas diffusion layer, particularly to guarantee the position of the gas diffusion layer and the width of the gas chamber, it is particularly advantageous to use a contact base as a spacer. Here, the contact base needs to be connected to the cathode plate. Conversely, it is specified to be in contact with the gas diffusion layer. Obviously, the contact base is located in or penetrates the gas chamber.
[0043] The contact base can be implemented in various ways. Therefore, on the one hand, the contact base can be inserted into the corresponding receiving portion in the cathode plate by means of a plug-in connection.
[0044] However, it is advantageous that the contact base and the cathode plate are securely connected, simplifying the manufacturing process. For example, threaded fastening is feasible. However, it is particularly advantageous that the cathode plate and the contact base are manufactured integrally or as a single unit. This can be achieved, for example, by casting or additive manufacturing methods.
[0045] In a particularly advantageous manner, the contact base enables a conductive connection between the cathode plate and the current bridge. It is obvious that a conductive connection between the cathode plate and the contact base is necessary for this. Accordingly, it is particularly advantageous that the current bridge is conductively connected to the contact base. Since the current bridge penetrates the gas diffusion layer and the contact base rests against the gas diffusion layer, the necessary structural dimensions of the current bridge are thus reduced.
[0046] In the presence of a contact base, the conductive connection between the current bridge and the cathode plate can be achieved in different ways.
[0047] In a particularly advantageous embodiment, the current bridge is detachably inserted into a receiving portion in the contact base. This allows for greater design freedom in the contact of the catalyst layer via the current bridge.
[0048] In one alternative variation, the current bridge is specified to be securely connected to the contact base. Similar to the connection between the contact base and the cathode plate, this can be achieved, for example, via a threaded connection. Similarly, an integral or monolithic structure of the contact base and the current bridge is also feasible.
[0049] It is not absolutely necessary for every current bridge to be connected to the lateral connector. Instead, it is advantageous to stipulate that bridge heads are arranged on the current bridges without lateral connectors, the bridge heads serving as disks connected to the corresponding current bridges and electrically connected to the catalyst layer surrounding the current bridges. In this respect, a portion of the current bridge is electrically connected to the lateral connector, and another portion of the current bridge has a bridge head.
[0050] In order to connect the bridge head and / or lateral connector to the current bridge, it can be specified that the conductive connection is established by the abutment of the bridge head and / or lateral connector on the current bridge.
[0051] If the current bridge is securely connected to the contact base, the bridge head and / or at least one lateral connector utilizing the aforementioned connection at the current bridge is particularly advantageous in that case.
[0052] Alternatively, it is particularly advantageous that the bridgehead and / or lateral connectors are securely and / or integrally connected to the current bridge.
[0053] If the current bridge is detachably inserted into the contact base, a secure connection between the bridge head and / or the lateral connector and the current bridge is particularly advantageous.
[0054] In any case, it is particularly advantageous that there is no conductive connection in the water chamber from the current bridge and the lateral connectors, and (if present) the bridge head to the electrolyte. For this purpose, a non-conductive coating can be provided, for example.
[0055] If a non-conductive cladding is provided, it is always possible to alternatively provide a non-conductive covering or sheath. However, small structural dimensions for electrical insulation are advantageously achieved using non-conductive cladding.
[0056] Furthermore, depending on the size of the electrolytic cell and the rigidity of the gas diffusion layer and the catalyst layer, it is advantageous to arrange at least one spacer in the water chamber. Here, it is necessary to provide a defined position for the spacer between the anode plate and the catalyst layer.
[0057] Therefore, the spacer should ensure that the spacing between the anode plate and the catalyst layer does not change due to deformation of the catalyst layer.
[0058] By combining the contact base with spacers, the positions of the catalyst layer and the gas diffusion layer can be reliably determined. This ensures that the catalyst layer adheres planarly to the gas diffusion layer.
[0059] In the first option, it can be specified that multiple spacers are arranged in the water chamber. Here, the spacers must be securely connected to the anode plate so that their positions are determined.
[0060] In the second option, it can be specified that a single-piece spacer is placed between the anode plate and the catalyst layer in the water chamber. To ensure the most unobstructed flow possible in the water chamber, the spacer is designed as a grid. Here, the covered area of the anode plate and the catalyst layer should be as small as possible, and the grid-shaped spacer is otherwise spaced apart from the anode plate and, in particular, from the catalyst layer.
[0061] In both cases, it is particularly advantageous that the spacer is attached to the catalyst layer on the side of the catalyst layer at the corresponding current bridge and in sections around the current bridge. Attachment is advantageously made at least at the location of the current bridge at the bridge head or on the transverse connector.
[0062] Particularly advantageously, the contact between the bridge abutment and / or the lateral connector on the catalyst layer can be improved by abutting one or more spacers on the bridge abutment and / or the lateral connector.
[0063] Advantageously, it is feasible to securely arrange the bridge abutments and / or lateral connectors at the grid-like spacers or at multiple spacers connected to the anode plates. This simplifies the assembly process. For example, the bridge abutments and / or lateral connectors can be secured by adhesive bonding.
[0064] Particularly advantageous when using mesh-like spacers is the secure connection of the bridge heads and / or lateral connectors. Depending on the manufacturing method, these can be cast on the cathode side. Alternatively, the spacers can be made of a conductive material that forms the bridge heads and / or at least one lateral connector on the cathode side and is insulated relative to the anode plate.
[0065] If a spacer is used and the core of the spacer is made of a conductive material, it is particularly advantageous to specify that no conductive connection is provided from the spacer to the electrolyte in the water chamber. For this purpose, the spacer is advantageously provided with a non-conductive coating (or other electrical insulation) on the side facing the water chamber.
[0066] Similarly (if present), a conductive connection from the current bridge to the anode plate is not permitted via the spacer. Therefore, if the core of the spacer is made of a conductive material, the surfaces facing the anode plate and / or the catalyst layer must also have a non-conductive coating (or other electrical insulation).
[0067] Instead of electrically connecting the current bridges to the cathode plate via contact bases, it is feasible to provide at least one current distributor. Here, the current distributor is fixed to the cathode plate for positioning and for electrical connection. Furthermore, it is specified that at least two current bridges are electrically connected to one current distributor respectively. Preferably, one current distributor is present for each of the four contact current bridges. Here, the presence or absence of contact bases for supporting the gas diffusion layer is irrelevant.
[0068] In a simple implementation, similar to the implementation with a contact base, the current distributor is essentially located in the gas chamber.
[0069] The use of the current distributor preferably achieves a flexible implementation, making elastic deformation of the current distributor between the current bridge and the cathode plate feasible. This avoids unacceptable pressure loads caused by different dimensions and / or thermal expansion in the electrolytic cell—especially when the spacing is determined by the outer casing.
[0070] In this case, the support of the gas diffusion layer can also be advantageously achieved through a flexible current distributor. Therefore, its position and contact with the catalyst layer can be more advantageously ensured without the need for an additional contact base.
[0071] To electrically connect the current bridge to the current distributor, it is possible to specify that the current bridge is loosely attached to the current distributor. This is particularly advantageous if the current bridge is provided with a firmly connected bridge head and / or lateral connector. This allows for a simpler assembly of the current bridge from the anode side, opposite the current distributor on the cathode side, through the catalyst layer and gas diffusion layer.
[0072] On the other hand, it can be specified that the current bridge and the current distributor are firmly connected. This requires assembling the current distributor with the current bridge from the cathode side through the gas diffusion layer.
[0073] The number of current bridges per catalyst layer area can be selected differently. A larger number results in a more uniform voltage distribution across the catalyst layer area. However, a problem arises simultaneously: as the number of current bridges increases, the effective area of the catalyst layer decreases. Furthermore, a large number of current bridges increases the cost of manufacturing the electrolytic cell.
[0074] Therefore, it has proven advantageous to have at least one current bridge per 10 cm² of catalyst layer area. Conversely, the number of current bridges should not be chosen to be greater than one per 1 cm². Attached Figure Description
[0075] Figure 1 A first embodiment of the structure for an electrolytic cell according to the invention is shown schematically in cross-section. Here, the connection from the current bridge to the cathode plate is established via a contact base.
[0076] Figure 2 A third embodiment of the structure for an electrolytic cell according to the invention is shown schematically in cross-section. Figure 2 Starting with the example, spacers are supplemented and arranged in the water chamber.
[0077] Figure 3 A fourth embodiment of the structure for an electrolytic cell according to the invention is shown schematically in cross-section. Instead, multiple spacers are used here, and a current distributor is present in the gas chamber instead of a contact base. Detailed Implementation
[0078] exist Figure 1 The structure of the electrolytic cell 11 according to a first embodiment of the present invention is schematically sketched in the simplified sketch. The structure of the electrolytic cell 11 is similarly shown in the simplified sketch in order from the cathode side 02 to the anode side 03.
[0079] A cathode plate 14 with adjacent gas chambers 06 is present on the cathode side 02. Furthermore, a contact base 16 is integrally attached to the cathode plate 14. The contact base 16 is present at the locations where current bridges 20 are respectively located.
[0080] In this specification, the contact base 16 is attached to the gas diffusion layer 08, thereby determining the position of the gas diffusion layer 08 on the cathode side 02.
[0081] The current bridge 20 on the anode side 03 of the catalyst layer 09 is either provided with a bridge head 18 or connected to the transverse connector 19 according to the invention.
[0082] Bridgehead 18 is conductively and annularly attached to catalyst layer 09 around current bridge 20. Similarly, transverse connector 19 is conductively attached to catalyst layer 09 in a point- or line-like manner in the region between the two current bridges 20.
[0083] Through the aforementioned implementation, the contact of the catalyst layer 09 is significantly improved. Considering the effective area coverage of the catalyst layer 09, it is important to note that the bridge head 18 or the transverse connector 19 is chosen only to be large enough to ensure reliable contact of the catalyst layer 09 when emanating from the current bridge 20.
[0084] The arrangement of the contact base 16, combined with the implementation of the current bridge 20 having an integral bridge head 18 or a transverse connector 19, enables continuous contact between the current bridge 20 and the contact base 16 through a plug-in connection.
[0085] If the position of the current bridge 20 is reliably determined by plug-in connection after assembly, the solution described above can simultaneously ensure the positions of the catalyst layer 09 and the gas diffusion layer 08 in the electrolytic cell 11.
[0086] exist Figure 2 Another embodiment of the electrolytic cell 21 according to the invention is schematically sketched, building upon the previous examples. In this regard, only discussions of... Figure 2 The differences from previous implementation schemes.
[0087] In the embodiment described, a grid-like spacer 17 is provided in the water chamber 07. Here, by using a grid-like shape for the spacer 17, it is intended to minimize obstruction to the free flow within the water chamber 07.
[0088] At least it is specified that the spacer 17 has a defined position in the water chamber 07. It is also necessary to provide a contact on the anode side 03 at the anode plate 05, and conversely, to provide a contact on the cathode side 02 at the position of the current bridge 20.
[0089] In the described embodiment, spacer 17 is provided to cover the corresponding bridge head 18 and transverse connector 19. It is also possible to specify that, for assembly, the current bridge 20 having the bridge head 18 or transverse connector is pre-fixed to the spacer 17, for example, by adhesive.
[0090] Furthermore, it can be preliminarily identified that the spacer surrounds the bridge head 18 and the transverse connector 19 towards the water chamber 07. When a non-conductive material is used for the spacer 17, it thus prevents the conductive connection of the electrolyte from the bridge head 18 to the water chamber 07.
[0091] exist Figure 3 Another embodiment of the electrolytic cell 31, based on empirical observation, is sketched. Unlike the previous two embodiments, the use of a contact base is omitted in this case.
[0092] To achieve a conductive connection from the current bridges 20 to the cathode plate 04, in this embodiment, a current distributor 26 is specified. The current distributor 26 is fixed to the cathode plate 04 and otherwise resembles a contact base located within the gas chamber 06. In this embodiment, it is now specified that each of the four current bridges 20 is conductively abutted against a current distributor 26.
[0093] Furthermore, it is specified that the current distributor 26 is designed to be elastically deformable, thereby compensating for inaccuracies in the position of the current bridge 20 attached to the current distributor 26, such inaccuracies being caused, for example, by tolerances or thermal bonding.
[0094] Furthermore, in the embodiments described above, instead of the grid-like spacers, a plurality of spacers 27 are now used, each of which is integrally fixed to the anode plate 25.
[0095] To prevent conductive connection between the spacer 27 and the electrolyte in the water chamber 07, it is further specified that the spacer 27 has a non-conductive coating 28 on the side facing the water chamber 07 and on the side facing the cathode side 02.
[0096] In addition, to simplify assembly, it can be specified that the corresponding current bridge 20 with bridge head 18 or transverse connector 19 is fixed to the corresponding spacer 27 by adhesive bonding, for example.
Claims
1. An electrolytic cell (01, 1, 21, 31) for CO2 electrolysis, the electrolytic cell having a cathode side (02) and an anode side (03), the electrolytic cell comprising, in a direct or indirect order: - Cathode plate (04, 14). -Air chamber (06). -Gas diffusion layer (08). -Catalyst layer (09). -Water chamber (07), and - Anode plate (05, 25); The electrolytic cell also includes multiple current bridges (10, 20), which are electrically connected to the cathode plate (04, 14) and the catalyst layer (09) and penetrate the gas diffusion layer (08) and the catalyst layer (09). Its features are, A transverse connector (19) is provided, which is electrically connected to at least two current bridges (20) on the anode side (03) of the catalyst layer (09) and electrically abuts against the catalyst layer (09).
2. The electrolytic cell (11, 21, 31) according to claim 1, wherein, The transverse connector (19) is securely and / or integrally connected to the corresponding current bridge (20).
3. The electrolytic cell (11, 21, 31) according to claim 2, characterized in that, A contact base (16) is provided, which is connected to the cathode plate (14) and abuts against the gas diffusion layer (08); Specifically, the contact base (16) is securely and / or integrally connected to the cathode plate (14).
4. The electrolytic cell (11, 21) according to claim 3, wherein, The current bridge (20) can be detachably inserted into the contact base (16) and electrically connected.
5. The electrolytic cell (11, 21, 31) according to any one of claims 1 to 3, characterized in that, A bridge head (18) is provided, which is electrically connected to one of the current bridges (20) on the anode side (03) of the catalyst layer (09) and electrically abuts against the catalyst layer (09).
6. The electrolytic cell (11, 21, 31) according to claim 5, wherein, The bridge head (18) is securely and / or integrally connected to the current bridge (20).
7. The electrolytic cell (11, 21, 31) according to any one of claims 1 to 6, wherein, The current bridge (10) and / or the bridge head (18) and / or the transverse connector (19) have a non-conductive coating pointing toward the water chamber (07).
8. The electrolytic cell (21, 31) according to any one of claims 1 to 7, characterized in that, At least one spacer (17) is provided, which is fastened in the water chamber (07) between the anode plate (05) and the catalyst layer (09).
9. The electrolytic cell (21, 31) according to claim 8, wherein, Multiple spacers (27) are securely connected to the anode plate (25).
10. The electrolytic cell (21, 31) according to claim 8, wherein, The spacer (17) is designed as a grid.
11. The electrolytic cell (21, 31) according to any one of claims 8 to 10, wherein, The spacers (17, 27) surround the bridge abutment (18) and / or the transverse connector (19).
12. The electrolytic cell (11, 21, 31) according to any one of claims 8 to 10, wherein, The spacers (17, 27) are made of non-conductive material, or at least have a non-conductive coating (28) pointing towards the water chamber (07).
13. The electrolytic cell (31) according to any one of claims 1 to 12, characterized in that, A current distributor (26) is provided, which is fixed at the cathode plate (04) and electrically connected to a plurality of current bridges (20).
14. The electrolytic cell (31) according to claim 13, wherein, The current distributor (26) is capable of elastic deformation between the cathode plate (04) and the current bridge (20).
15. The electrolytic cell (01, 11, 21, 31) according to any one of claims 1 to 14, wherein, Based on the area of the catalyst layer (09), there is at least one current bridge (10, 20) per 10 cm2 and at most one current bridge (10, 20) per 1 cm2.