Electrolysis cell and method for manufacturing an electrolysis cell

Abstract

The present invention relates to an electrolysis cell (10) comprising at least one substantially planar backwall (17), at least one current conducting part (20) and at least one electrode (12). In order to overcome the drawbacks of welding technologies commonly used in the connection of components of the electrolysis cell (10), it is suggested that a connection between the at least one backwall (17) and the at least one current conducting part (20) and / or a connection between the at least one support part (20) and the at least one electrode (12) is a clinching joint (22). Furthermore, the present invention relates to a method for manufacturing such an electrolysis cell (10).

Description

[0001] Electrolysis cell and method for manufacturing an electrolysis cell

[0002] The present invention relates to an electrolysis cell according to claim 1 and a method for manufacturing an electrolysis cell according to claim 14.

[0003] Electrolysis cells are nowadays usually made from metallic sheet metals which comprise beneficial electrical conductivity properties. Depending on the specific designation, either sheet metal pans for single element electrolysis cells or bipolar plates for filter press electrolysis cells are used. In any case, those are connected to current conducting parts and to the electrode by welding.

[0004] The welding technology, especially the commonly used laser welding technology, has several drawbacks. Firstly, laser welding consumes much time. This process step therefore constitutes a bottleneck for increasing the output quantity in the manufacturing of electrolysis cells. In the setup of new manufacturing lines or even manufacturing plants, a high level of experience in the specific laser welding process is required in order to achieve a similar high quality from the start of manufacturing on the new manufacturing line or in the new manufacturing plant.

[0005] Secondly, a further reduction of material thickness is very difficult to achieve, as the laser welding technology requires a certain minimum material thickness for obtaining a reliable welding quality.

[0006] Although laser welding introduces relatively low thermal energy and thus low mechanical strain in principle, when applied on larger areas or lengths it leads to significant residual stresses in the assembled structure. Due to this stress, a very thorough quality control is necessary. External leakages and mechanical damages due to faults in the weld positioning or by material deviations and defects need to be detected and prevented, also in the long term. Weld seam failures do not necessarily result in immediate leakages. But years of operation and exposure to thermal cycles, micro defects in the weld seam can develop into pores or cracks. Therefore small deviations in the welding process can have an enormous impact on the service life of the electrolysis cell, and the necessary quality control makes this process step both time consuming and expensive.It is therefore an objective of the present invention to provide an electrolysis cell in which the drawbacks of the laser welding technology are overcome. In a further aspect of the present invention, a method for manufacturing such an electrolysis cell shall be provided.

[0007] This objective is achieved by an electrolysis cell in accordance with claim 1. The further aspect is achieved by a method for manufacturing an electrolysis cell in accordance with claim 14. Preferred embodiments are subject of the dependent claims.

[0008] An electrolysis cell according to the present invention comprises at least one substantially planar backwall, at least one current conducting part and at least one electrode. A connection between the at least one backwall and the at least one current conducting part and / or a connection between the at least one current conducting part and the at least one electrode is a clinching joint.

[0009] Clinching is a mechanical fastening process used to join two or more components without the need for additional fasteners, heat or adhesives. It involves deforming the materials together using a punch and a die, creating an interlock that secures the components. The process is typically performed using a press machine, where the punch forces the materials into the die, forming a localized joint. It is energy-efficient and allows for high productivity, minimal maintenance and the absence of fumes or waste.

[0010] Using a clinching joint as a connection between the at least one backwall and the at least one current conducting part and / or as a connection between the at least one current conducting part and the at least one electrode provides several advantages. Compared to laser welding, clinching is a very quick fastening process. The aforementioned bottleneck in the manufacturing of electrolysis cells can thus be eliminated. The overall manufacturing output quantity can thus be increased, and the setup of new manufacturing lines or plants does not require exhaustive calibration or teaching.

[0011] In clinching, the material of the components is only deformed, without any risk of thermal or mechanical perforation. The quality control effort can thus be reduced, as only one geometrical criterion needs to be checked at each clinching joint. In particular, no leakage test needs to be performed, saving both time and costs.In a preferred embodiment of the invention, the at least one current conducting part is made of a sheet metal. This material has advantageous properties in terms of electrical conductivity and viscosity. The electrical conductivity is one of the key features in an electrolysis cell, as this component allows for the efficient transmission of an electrical current. The viscosity allows for the deformation during clinching without the risk of material breaking.

[0012] In an alternative preferred embodiment of the invention, the at least one current conducting part is made of a flexible material. Such a design allows for a high flexibility with regard to the positioning of the individual components, while reliably fulfilling the main task of transmitting a current.

[0013] In a further preferred embodiment of the present invention, a section of the at least one current conducting part is aligned parallel ly with the at least one backwall and / or the at least one electrode. Aligning the components which are to be connected by the clinching joint provides a safe, reliable and reproducible clinching process.

[0014] In conventional electrolysis cells, the current conducting parts often have an I-shape or are designed as so called l-webs. This design is necessary for creating a reliable connection when connected to the backwall by laser welding. By changing from laser welding technology to clinching, different designs for the current conducting parts become possible. In a preferred embodiment, the at least one current conducting part has an S-, Z-, L- or U-shape in cross-section. Those designs have in common that they all contain a substantially flat bottom section, which allows for a simple connection to the at least one backwall by forming a clinching joint. The upper section of the at least one current conducting part provides sufficient space for connecting the at least one electrode, either by forming a clinching joint or by conventional fastening technics.

[0015] A further advantage of the clinching technology is that more than two components can be connected with another in one fastening spot. In a preferred embodiment, the electrolysis cell comprises at least one contacting part or a second contacting backwall, wherein the at least one backwall is arranged between the at least one current conducting part and the at least one contacting part or the second contacting backwall, wherein the connection between all three components is a single clinching joint. Alternatively, the connectionbetween the at least one contacting part or the second contacting backwall and the at least one backwall is a clinching joint.

[0016] In welding, a material-lock is formed by locally melting the material of the components to be connected. This requires the materials of the components to have similar thermo-physical properties, in particular with regard to the melting points, which need to be identical or at least very similar. In practice, this means that welding can almost exclusively by used when the components to be connected consist of the same material.

[0017] Clinching on the other hand is independent of the melting points of the materials to be connected. Therefore, in a preferred embodiment of the invention, the at least one backwall and / or the at least one current conducting part and / or the at least one contacting part or the second contacting backwall and / or the at least one electrode are made from different materials. This freedom of material selection allows to design the electrolysis cell with regard to other properties such as a light weight or an improved electrical conductivity. Alternatively, as with conventional laser welding technology, the at least one backwall and / or the at least one current conducting part and / or the at least on contacting part or the second contacting backwall and / or the at least one electrode can be made from the same material.

[0018] In a preferred embodiment of the invention, the materials of the at least one backwall and / or the at least one current conducting part and / or the at least one contacting part or the second contacting backwall and / or the at least one electrode are chosen from titanium (Ti), nickel (Ni), cupper (Cu), aluminum (Al) and steel alloys. This wide range of materials allows a user or designer to select that optimal material for each component with regard to the desired properties of the electrolysis cell.

[0019] Furthermore, it is possible to use a base material with a certain coating as the at least one backwall and / or the at least one current conducting part and / or the at least one contacting part or the second contacting backwall and / or the at least one electrode. This design options provides for additional possibilities to save material and reduce costs while obtaining the desired physical, mechanical and / or electrochemical properties.In another preferred embodiment, the thickness of the at least one backwall and / or the at least one current conducting part and / or the at least one contacting part or the second contacting backwall and / or the at least one electrode is greater than 0.1 mm, preferably greater than 0.3 mm, more preferably greater than 0.6 mm, and smaller than 2 mm, preferably smaller than 1.6 mm, more preferably smaller than 1.3 mm.

[0020] In conventional electrolysis cells, the reduction of material thickness is limited by the welding technology, as this fastening method requires a certain minimum material thickness for producing a safe, reliable and reproducible connection. By using clinching joints, the material thickness can be reduced, thus allowing for an optimization of weight and costs.

[0021] According to a preferred embodiment of the invention, the clinching joint comprises a clinching rivet. This means that in the fastening step the punch is equipped with a rivet, which then presses the components to be connected into the die. The clinching rivet itself is not removed from the connection but remains a part of it. In that way, the clinching rivet can act as the contacting part. By such means, the stiffening of the clinching joint can be further increased while simultaneously strengthening the connection.

[0022] In another preferred embodiment of the invention, the clinching joint has a circular shape in a top view. The circular shape, which is generated by a circular punch pressing the components to be connected into a circular die, ensures that the strain on the materials is similar over the whole circumference of the connection. This is in contrast to e.g. rectangular shapes, in which the strain in the corners is higher, thus creating predetermined breaking points.

[0023] In yet another preferred embodiment, a section of the current conducting part located between two adjacent clinching joints is cut out. Besides the additional savings in material and cost, this feature enhances the electrical conductivity characteristics. The actual contact surface between the at least one backwall and the at least one current conducting part and the at least one contacting part or the second contacting backwall is thus reduced to a clinching joint and its immediate surroundings. The electrical current transmitted from one component to another is thereby evenly distributed in a predetermined manner. Undesired local heat generation and efficiency losses can thus be avoided.A method for manufacturing an electrolysis cell comprises in a first step a parallel alignment of a substantially planar section of the at least one current conducting part with the at least one backwall or with a substantially planar section of the at least one electrode. In a second step, a punch of a clinching tool is pressing a material of the at least one current conducting part and a material of the at least one backwall or the at least one electrode into a die of the clinching tool, thus forming a clinching joint.

[0024] By using a clinching tool and forming a clinching joint as connection between the at least one current conducting part and the at least one backwall or the at least one electrode, the previous bottleneck in the manufacturing of electrolysis cells is eliminated. The time required for the fastening process is reduced, thereby accelerating the manufacturing process and providing an opportunity to increase the output quantity. Furthermore, clinching is an easy-to-control technology with good reproducibility. As the material of the components to be connected is only deformed, but not thermally or mechanically perforated, end-of-line quality control can be simplified, eliminating the leakage test compared to laser welding technology and also reducing the necessary effort for visual inspections. This allows for a further increase in output quantity as well as for cost reduction.

[0025] In a preferred embodiment of the method, a substantially planar section of at least one contacting part or the second contacting backwall is aligned parallel ly with the at least one backwall and the substantially planar section of the at least one current conducting part, thus forming a clinching joint of at least three components. In other words, the contacting part or the second contacting backwall, the backwall and the the current conducting part are connected by a single clinching joint.

[0026] In a further preferred embodiment, the punch of the clinching tool is equipped with a clinching rivet which remains in the clinching joint. In such an embodiment, the punch of the clinching tool itself does not have direct contact with either of the components to be connected, but only presses the clinching rivet into the materials which are thereby pressed into the die of the clinching tool. Contrary to the punch, the clinching rivet is not removed at the end of the clinching process but remains in the clinching joint, thus acting as the contacting part. This increases the stiffness of the clinching joint and strengthens the connection of the connected components.The invention is explained in more detail below with reference to the accompanying drawings. In the figures show:

[0027] Fig. 1 an exemplary embodiment of an electrolysis cell in accordance with the present invention in a schematic view;

[0028] Fig. 2 a detailed view of a half shell assembly according to Fig. 1 ;

[0029] Fig. 3 a detailed schematic view of a clinching joint connecting a backwall and a current conducting part;

[0030] Fig. 4 an illustration of a clinching tool;

[0031] Fig. 5 a detailed schematic view of a clinching joint connecting a backwall, a second contacting backwall and a current conducting part;

[0032] Fig. 6 a detailed view of a clinching joint comprising a clinching rivet connecting a backwall and a current conducting part;

[0033] Fig. 7 a perspective view of a section in which a backwall and a current conducting part are connected by clinching joints;

[0034] Figs. 8a-d different embodiments of electrolysis cells with differently shaped current conducting parts in a schematic view; and

[0035] Fig. 9 an exemplary embodiment of an electrolysis cell with a filter press design.

[0036] Fig. 1 shows an exemplary embodiment of an electrolysis cell 10 in accordance with the present invention comprising a pair of half shell assemblies 11. Each half shell assembly may include an electrode 12 accommodated in a chamber 13. A sheet-like separator or membrane 14, such as an ion exchange membrane or diaphragm, may be arranged between the opposing electrodes 12.

[0037] The half shell assembly 11 includes a half shell comprising a backwall plate 15 and a backwall frame 16, which together form a backwall 17. The backwall plate 15 extends in the cell height direction as well as the cell width direction and faces the electrode 12 when assembled. The backwall frame 16 extends from the periphery of the backwall plate 15 so as to define a volumetric space for the chamber 13. The backwall frame 16 has a flange portion 18 at its end opposite the backwall plate 15.The electrode 12 is arranged within the chamber 13 defined by the half shell assemblies 11 , serving as the site for electrochemical reactions. Depending on which side the electrode 12 is arranged with respect to the separator or membrane 14, the electrode 12 functions as either the cathode or the anode of the electrolysis cell 10.

[0038] The half shell assembly 11 may further include one or more current conducting parts 20 that are designed to transmit a current between the electrode 12 and the backwall 17. The one or more current conducting parts 20 may be designed to withstand the operational stresses and thermal expansion that occur during electrolysis.

[0039] Fig. 2 shows a detailed view of a half shell assembly 11 according to Fig. 1. The half shell assembly 11 comprises a backwall 17 which defines the chamber 13. Facing the open side of chamber 13 and arranged therein is the electrode 12. The electrode 12 is fixed to the backwall 17 and secured in the chamber 13 through one or more current conducting parts 20. In the depicted embodiment, the current conducting parts 20 have a Z-shape, with a substantially planar bottom section aligned parallelly with the backwall plate 15 of the backwall 17 and a substantially planar top section aligned parallelly with the electrode 12.

[0040] The connection between each current conducting part 20 and the electrode 12 is a conventional welding joint 21 , while the connection between each current conducting part 20 and the backwall 17 is a clinching joint 22, which will be explained in more detail in the following.

[0041] Fig. 3 shows a schematic view of a clinching joint 22 connecting a backwall 17 with a current conducting part 20, while Fig. 4 shows a clinching tool comprising a punch 23 and a die 24 used to create clinching joint 22. During clinching, the material of the backwall 17 and the current conducting part 20 is pressed into the die 24 by the punch 23. This deformation creates an undercut in the component that is placed closer to the die 24, which is the current conducting part 20 in the illustrated embodiment. In the same step, the undercut is filled with material from the backwall 17. Since the material which fills the undercut is not separated from the rest of the material of the backwall 17, a secure connection between the backwall 17 and the current conducting part 20 is formed.Fig. 5 shows a schematic view of a clinching joint 22 connecting three separate components in a single connection. In addition to the embodiment according to Fig. 3, a second contacting backwall 19 is arranged at the side of the backwall 17 opposite of the current conducting part 20. The undercut created in the material of the current conducting part 20 during clinching is filled by material from the backwall 17. In the backwall 17 itself there is formed an undercut during clinching, which is filled by material of the second contacting backwall 19.

[0042] In the embodiments illustrated in Figs. 3, 4 and 6, the materials of the backwall 17, current conducting part 20 and second contacting backwall 19 can be (partly) identical or different from another. Clinching allows the connection of materials having different thermo-physical properties. Alternatively, e.g. if certain surface characteristics of one or more of the components are desired, it is possible to use a base material having a particular coating, through which these characteristics can be achieved.

[0043] Fig. 6 shows a different embodiment of a clinching joint 22, comprising a clinching rivet 26 which acts as a contacting part. While the deformation of the current conducting part 20 is similar to that of the embodiment shown in Fig. 3, due to the different shape of the clinching rivet 26 compared to the punch 23 of Fig. 4 an undercut is also formed in the backwall 17. This undercut in the backwall 17 is filled by the clinching rivet 26, which remains an integral part of the clinching joint 22, providing stiffness and increasing the strength of the connection.

[0044] Fig. 7 shows a perspective illustration of a connection between a backwall 17 and a current conducting part 20. The current conducting part 20 is L-shaped, with the bottom section aligned parallelly with the backwall 17. Several clinching joints 22 form a connection between the backwall 17 and the current conducting part 20. Several cut-outs 27 are arranged in between the clinching joints 22, thus essentially reducing the contact surface between the backwall 17 and the current conducting part 20 to the clinching joints 22 and their immediate surroundings. This design allows for an even and predetermined transmission of electrical current from the current conducting part 20 to the backwall 17, thus preventing a local heat generation and a loss in efficiency of the electrolysis cell 10.Figs. 8a-d show schematic views of electrolysis cells 10 with varying shapes of the current conducting parts 20. The embodiment displayed in Fig. 8a comprises Z-shaped current conducting parts 20, while the embodiment displayed in Fig. 8b comprises U-shaped current conducting parts 20, which are arranged so that the open side faces the electrode 12. In the embodiment displayed in Fig. 8c, the current conducting parts 20 are also U-shaped, with the open side facing the backwall frame 16 and the leg arranged closer to the electrode 12 being shorter than the leg arranged closer to the respective backwall 17. In the embodiment of the electrolysis cell 10 shown in Fig. 8d, the current conducting part 20 is L-shaped, with one leg arranged parallelly to the backwall 17 and the other leg protruding towards the electrode 12.

[0045] Fig. 9 is a schematic view of an electrolysis cell 10 in filter press design. The components and their arrangement are similar to that of the half shell assembly 11 of Fig. 2. On the side of the backwall 17 opposite the current conducting parts 20 and the electrode 12, a second contacting backwall 19 is arranged, which is a part of an adjacent electrolysis cell 10. In this embodiment, each clinching joint 22 connects the current conducting part 20, the backwall 17 and the second contacting backwall 19 in a single fastening spot. This allows for a compact and robust electrolysis cell 10 in filter press design.240105P10WC

[0046] Reference sign list

[0047] 10 Electrolysis cell

[0048] 11 Half shell assembly

[0049] 12 Electrode

[0050] 13 Chamber

[0051] 14 Membrane

[0052] 15 Backwall plate

[0053] 16 Backwall frame

[0054] 17 Backwall

[0055] 18 Flange portion

[0056] 19 Second contacting backwall

[0057] 20 Current conducting part

[0058] 21 Welding joint

[0059] 22 Clinching joint

[0060] 23 Punch

[0061] 24 Die

[0062] 25

[0063] 26 Clinching rivet

[0064] 27 Cut-out

Claims

Claims1. Electrolysis cell (10) comprising at least one substantially planar backwall (17), at least one current conducting part (20) and at least one electrode (12), wherein a connection between the at least one backwall (17) and the at least one current conducting part (20) and / or a connection between the at least one current conducting part (20) and the at least one electrode (12) is a clinching joint (22).

2. Electrolysis cell (10) according to claim 1 , wherein the at least one current conducting part (20) is made of a sheet metal.

3. Electrolysis cell (10) according to claim 1 , wherein the at least one current conducting part (20) is made of a flexible material.

4. Electrolysis cell (10) according to any one of the preceding claims, wherein a section of the at least one current conducting part (20) is aligned paral lelly with the at least one backwall (17) and / or the at least one electrode (12).

5. Electrolysis cell (10) according to any one of the preceding claims, wherein the at least one current conducting part (20) has a S-, Z-, L- or U-shape in crosssection.

6. Electrolysis cell (10) according to any one of the preceding claims, further comprising at least one contacting part or a second contacting backwall (19), wherein the connection between the at least one current conducting part (20) and the at least one backwall (17) and the at least one contacting part or the second contacting backwall (19) is a clinching joint.

7. Electrolysis cell (10) according to any one of the preceding claims, wherein the at least one current conducting part (20) and / or the at least one backwall (17) and / or the at least one contacting part or the second contacting backwall (19) are made from identical or different materials.

8. Electrolysis cell (10) according to claim 7, wherein the materials of the at least one backwall (17) and / or the at least one current conducting part (20) and / or the at least one contacting part or the second contacting backwall (19) and / or theat least one electrode (12) are chosen from titanium (Ti), nickel (Ni), cupper (Cu), aluminum (Al) and steel alloys.

9. Electrolysis cell (10) according to any one of the preceding claims, wherein the at least one current conducting part (20) and / or the at least one backwall (17) and / or the at least one contacting part or the second contacting backwall (19) are made from a coated base material, preferably from a coated sheet metal.

10. Electrolysis cell (10) according to any one of the preceding claims, wherein a thickness of the at least one backwall (17) and / or the at least one current conducting part (20) and / or the at least one contacting part or the second contacting backwall (19) and / or the at least one electrode (12) is greater than 0.1 mm, preferably greater than 0.3 mm, more preferably greater than 0.6 mm, and smaller than 2 mm, preferably smaller than 1.6 mm, more preferably smaller than 1.3 mm.

11. Electrolysis cell (10) according to any one of the preceding claims, wherein the clinching joint comprises a clinching rivet (26).

12. Electrolysis cell (10) according to any one of the preceding claims, wherein the clinching joint has a circular shape in a top view.

13. Electrolysis cell (10) according to any one of the preceding claims, wherein a section of the current conducting part (20) and / or the contacting part located between two adjacent clinching joints (22) is cut out.

14. Method for manufacturing an electrolysis cell (10) according to any one of the preceding claims, wherein a substantially planar section of the at least one current conducting part (20) is aligned parallelly with the at least one backwall (17) or a substantially planar section of the at least one electrode (12), and a punch (23) of a clinching tool is pressing a material of the at least one current conducting part (20) and a material of the at least one backwall (17) or the at least one electrode (12) into a die (24) of the clinching tool, thus forming a clinching joint (22).

15. Method according to claim 14, wherein a substantially planar section of at least one contacting part or the second contacting backwall (19) is aligned parallelly with the at least one backwall (17) and the substantially planar section of the at14 / 15240105P10WOleast one current conducting part (20), thus forming a clinching joint (22) of three components.

16. Method according to claim 14 or 15, wherein the punch (23) of the clinching tool is equipped with a clinching rivet (26) which remains in the clinching joint (22).

Images