Method and device for producing a bipolar plate

Abstract

The invention relates to a method (100) for producing a functional assembly (200), the method (100) involving: - providing (101) a channel element (201), - providing (103) a bipolar plate element (203), - transferring (105) material in at least one contact region (207) of the channel element (201) in order to contact the bipolar plate element (203), the transfer (105) of the material being carried out by means of a laser (214) which melts the material and forms a material accumulation (205) at at least one point, and - connecting (107) the bipolar plate element (203) to the channel element (201) in that the bipolar plate element (203) is welded to each material accumulation (205) formed on the channel element (201).

Description

[0001] R.417502

[0002] - 1 -

[0003] Description

[0004] title

[0005] Method and apparatus for manufacturing a bipolar plate

[0006] The presented invention relates to a method for manufacturing a functional group, a bipolar plate, an electrochemical energy converter and a welding device according to the attached claims.

[0007] State of the art

[0008] In particular, functional groups with a precious metal coating are used in electrolysis systems to reduce contact resistance and prevent a deterioration of resistance due to a growing oxide layer over the lifetime of the functional group.

[0009] Such precious metal coatings are complex to manufacture and expensive.

[0010] Disclosure of the invention

[0011] Within the scope of the presented invention, a method for manufacturing a bipolar plate, a bipolar plate, an electrochemical energy converter and a welding device for manufacturing the functional group are presented.

[0012] Further features and details of the invention will become apparent from the respective dependent claims, the description, and the drawings. Features and details described in connection with the inventive method or the inventive welding apparatus naturally also apply in connection with R.417502 of the invention.

[0013] - 2 -

[0014] functional group or the electrochemical energy converter according to the invention and vice versa, so that with regard to the disclosure of the individual aspects of the invention, mutual reference is always made or can be made.

[0015] The presented invention serves in particular to provide a possibility for a cost-efficient electrochemical energy converter.

[0016] Thus, according to a first aspect of the presented invention, a method for manufacturing a functional group is presented.

[0017] The presented method comprises providing a channel element, providing a bipolar plate element, transferring material to at least one contact area of ​​the channel element for contacting the bipolar plate element, wherein the transfer of the material is carried out by means of a laser which melts the material and forms a material accumulation at at least one location, and connecting the bipolar plate element to the channel element by welding the bipolar plate element to respective material accumulations formed on the channel element.

[0018] The presented invention is based on two structures, namely a bipolar plate element and a channel element, in particular a so-called "flow-field", for distributing operating fluids in a cell of an electrochemical energy converter, such as an electrolysis system.

[0019] The bipolar plate element can, for example, be a flat, particularly rigid, metal part and, optionally, form a bipolar plate together with the channel element or on its own, i.e., without the channel element.

[0020] The channel element can be, for example, a profiled, especially embossed, metal part that is particularly flexible.

[0021] The channel element serves to guide operating fluids through a cell of an electrochemical energy converter. For this purpose, the channel element forms a multitude of channels. R.417502

[0022] - 3 -

[0023] According to the invention, the bipolar plate element and the channel element are joined together by a laser welding process. For this purpose, it is provided that a number of material accumulations are first formed on the channel element by melting and transferring, i.e., moving or rearranging, a metal forming the channel element using a laser. This means that molten material is transferred along the channel element so that the molten material accumulates at a predetermined location and forms a material accumulation there, such as a sphere or a mound.

[0024] After the material accumulations have formed on the channel element, they are used to weld the channel element to the bipolar plate element.

[0025] Due to the material accumulations, the presented method enables local gap-free welding in the respective welding areas, as the position of the material accumulations is known very precisely.

[0026] Furthermore, the presented method enables concealed welding at aspect ratios greater than 2.

[0027] Furthermore, the presented method enables the use of embossed or deep-drawn channel elements for the production of a bipolar plate.

[0028] Furthermore, the presented method eliminates the need for platinum coatings, as electrical conduction between the channel element and the bipolar plate element is ensured by welds. Accordingly, only coatings necessary for chemical function are required, and coatings for stable electrical conduction are omitted.

[0029] Furthermore, the presented method allows for flexibility in the process chain, enabling the coating sequence of PTL -> Platinum / BPP -> Gold to be applied before or after laser welding. R.417502

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[0031] Furthermore, the presented method enables the assurance of a smaller contact resistance over the lifetime of the functional group and the generation of stiffness of the functional group from flexible individual parts, so that their thickness can be reduced or minimized.

[0032] Furthermore, the presented method enables a particularly clean manufacturing process, so that no metals are transferred to electrodes and the risk of cell poisoning of a corresponding electrochemical cell is minimized.

[0033] The presented method utilizes the effect that liquid melt moves within a channel element due to surface tension. Accordingly, the melt can be transferred along a predefined trajectory and concentrated into a material accumulation at a predetermined point or area.

[0034] It may be provided that, prior to connecting the bipolar plate element to the channel element, the channel element is welded to a porous transport material on a first side, and that the connection of the bipolar plate element to the channel element takes place on a second side opposite the first side.

[0035] The presented method is particularly advantageous for welding a channel element, already welded on one side to a porous transport material, to a bipolar plate element. For this purpose, material accumulations as provided for in the invention are formed and then precisely welded to the bipolar plate element by directing the laser beam from a direction opposite the porous transport material onto the bipolar plate element. Due to the material accumulations, the welding of the channel element to the bipolar plate element is precise even when the laser beam is directed from a direction opposite the porous transport material onto the bipolar plate element, thus creating a robust and electrically conductive connection between the bipolar plate element and the channel element. R.417502

[0036] - 5 -

[0037] It may also be provided that, during the transfer of the material in the at least one contact area by the laser, at least one recess is created, so that a material accumulation forms at at least one end of the at least one recess.

[0038] A recess, especially a hole, leads to a particularly large amount of transferred material and a correspondingly large accumulation of material.

[0039] It may also be provided that, during the transfer of the material in the at least one contact area by the laser, several recesses are created, which are in particular arranged in a star shape and lead to a central accumulation of material.

[0040] Several recesses allow for a particularly large accumulation of material, resulting in a particularly large-area connection between the channel element and the bipolar plate element.

[0041] It may also be provided that, when connecting the bipolar plate element with the channel element, the laser acts on a respective material accumulation on a side of the bipolar plate element opposite the channel element, passing through the bipolar plate element.

[0042] The laser can heat the bipolar plate element, particularly if it is made of titanium, to melt the channel element. Alternatively, the laser can melt the bipolar plate element, particularly if it is made of stainless steel, to create direct access to the channel element, allowing it to be irradiated directly with the laser.

[0043] It may also be provided that the contact area of ​​the channel element is concave. R.417502

[0044] - 6 -

[0045] A concave contact area allows the bipolar plate element to come into contact with the contact area of ​​the channel element at the edges or margins of the contact area or a corresponding recess.

[0046] It may also be provided that, during the transfer of the material in at least one contact area, the laser is moved along an asymmetric curve.

[0047] An asymmetrical curve along which the laser is moved means that the melt moves completely or mostly to one end of the contact area and forms a correspondingly large accumulation of material there.

[0048] It may also be stipulated that the channel element is flexible when it is provided. That is, the channel element is provided in a flexible state.

[0049] A flexible channel element is particularly cost-effective to manufacture, thus providing a particularly cost-efficient functional group which in turn can be part of a particularly cost-efficient electrochemical energy converter.

[0050] It may also be provided that the channel element remains clamped in a clamping device at one position throughout the entire process.

[0051] Because the channel element remains clamped in a clamping device at one position throughout the entire process, the position of the respective material accumulations is known very precisely, so that the positions for welding the channel element to the bipolar plate element can also be made particularly precisely, namely at the known positions of the material accumulations.

[0052] It may also be provided that the support plate is positioned on the respective material accumulations, held down, and then secured with the R.417502

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[0054] Material accumulations are welded together, with the holding down being achieved by mechanical pressure and / or the application of a vacuum.

[0055] To provide mechanical pressure, the bipolar plate element or the stack of bipolar plate element and channel element can be weighted down, for example, with a weight, preferably a plate weight.

[0056] According to a second aspect, the presented invention relates to a functional group for an electrochemical energy converter, wherein the functional group is produced by a possible embodiment of the presented method.

[0057] Due to the presented method, the functional group shown is particularly cost-efficient. In particular, the functional group exhibits a zero-joint connection in the area between the bipolar plate element and the channel element.

[0058] For example, the bipolar plate element can be between 0.2 mm and 1.2 mm thick, preferably 0.5 mm.

[0059] For example, the channel element can be between 0.05 mm and 0.15 mm thick, preferably 0.1 mm.

[0060] It may be intended that the functional group does not have a platinum coating.

[0061] It may also be provided that the bipolar plate element and / or the channel element is made of stainless steel.

[0062] Stainless steel is a robust and cost-efficient material, so a corresponding functional group is also particularly cost-efficient and robust.

[0063] It may still be provided that the bipolar plate element and / or the channel element is made of titanium. R.417502

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[0065] Titanium is a particularly robust material, especially resistant to thermal stress, so a corresponding functional group is also particularly robust, especially resistant to thermal stress.

[0066] Accordingly, the presented functional group can be a titanium functional group, which, for example, includes titanium elements.

[0067] According to a third aspect, the presented invention relates to an electrochemical energy converter, wherein the electrochemical energy converter comprises a number of the presented functional groups.

[0068] Due to the functional groups presented, the electrochemical energy converter is particularly robust and cost-efficient.

[0069] The electrochemical energy converter presented can be, for example, an electrolysis system or a fuel cell system.

[0070] According to a fourth aspect, the presented invention relates to a welding device for manufacturing a functional group for an electrochemical energy converter.

[0071] The presented welding device comprises a laser welding robot and a computing unit configured to carry out a possible embodiment of the presented process using the laser welding robot.

[0072] In the context of the presented invention, a computing unit is to be understood as a computer, a processor, a control unit or any other programmable circuit.

[0073] Advantages described in detail with respect to the method for producing a functional group according to the first aspect of the invention apply equally to the functional group according to the second aspect of the invention and to the electrochemical energy converter according to the third aspect of the invention and to the welding apparatus according to the fourth aspect of the invention, and vice versa. R.417502

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[0075] Further advantages, features, and details of the presented invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination.

[0076] They each show schematically:

[0077] Figure 1 shows a possible embodiment of the presented method,

[0078] Figure 2 shows a cell element with a possible configuration of the presented bipolar plate.

[0079] Figure 3 shows a possible embodiment of the presented electrochemical energy converter, and

[0080] Figure 4 shows a possible embodiment of the welding device presented.

[0081] Fig. 1 shows a method 100 for producing a functional group 200 as shown, for example, in Fig. 2.

[0082] The method 100 comprises a first provisioning step 101 in which a channel element 201 is provided, and a second provisioning step 103 in which a bipolar plate element 203 is provided.

[0083] Furthermore, the method 100 comprises a transfer step 105 in which material is transferred to at least one contact area of ​​the channel element 201 for contacting the bipolar plate element 203, wherein the transfer of the material is carried out by means of a laser which melts the material and forms a material accumulation 205 at at least one location.

[0084] Furthermore, the method 100 comprises a connection step 107 in which the bipolar plate element 203 is connected to the channel element 201 by R.417502

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[0086] the bipolar plate element 203 is welded to the respective material accumulations 205 formed on the channel element 201.

[0087] Fig. 2 shows a cell element 210 comprising a functional group 200 and a porous transport layer 212.

[0088] The functional group 200 comprises a channel element 201 and a bipolar plate element 203.

[0089] The channel element 201 forms a material accumulation 205 in a contact area 207 for contacting the bipolar plate element 203.

[0090] A laser 214 heats the bipolar plate element 203 in the area of ​​the material accumulation 205 to such an extent that it is welded to the material accumulation 205 and, consequently, to the channel element 201.

[0091] Figure 3 shows an electrochemical energy converter 300. The electrochemical energy converter 300 comprises a cell stack 301 in which a plurality of cells 303 are arranged, each comprising functional groups 200, for example, according to Figure 2.

[0092] Fig. 4 shows a welding device 400 for the production of a functional group 200 e.g. according to Fig. 2, for an electrochemical energy converter 300 e.g. according to Fig. 3.

[0093] The welding device 400 comprises a laser welding robot 401 and a computing unit 403, which is configured to carry out the method 100 e.g. according to Fig. 1 by means of the laser welding robot 401.

Claims

R.417502 - 11 - Claims 1. Method (100) for producing a functional group (200), wherein the method (100) comprises: - Providing (101) a channel element (201), - Providing (103) a bipolar plate element (203), - Transferring (105) material into at least one contact area (207) of the channel element (201) to contact the bipolar plate element (203), wherein the transfer (105) of the material is carried out by means of a laser (214) which melts the material and forms a material accumulation (205) at at least one point, and - Connecting (107) the bipolar plate element (203) to the channel element (201) by welding the bipolar plate element (203) to the respective material accumulations (205) formed on the channel element (201).

2. Method (100) according to claim 1, characterized by that before connecting (107) the bipolar plate element (203) with the channel element (201), the channel element (201) is welded on a first side with a porous transport material (212) and the connection of the bipolar plate element (203) with the channel element (201) takes place on a second side opposite the first side.

3. Method (100) according to claim 1 or 2, characterized by that during the transfer (105) of the material in the at least one contact area (207) by the laser (214) at least one recess is created, so that a material accumulation (205) forms at at least one end of the at least one recess. R.417502 - 12 - 4. Method (100) according to one of the preceding claims, characterized in that that when transferring (105) the material in the at least one contact area (207) by the laser (214) several recesses are created, which are in particular star-shaped and lead to a central material accumulation (205).

5. Method (100) according to one of the preceding claims, characterized in that that when connecting the bipolar plate element (203) with the channel element (201), the laser (214) acts on a respective material accumulation (205) on a side of the bipolar plate element (203) opposite the channel element (201) through the bipolar plate element (203).

6. Method (100) according to one of the preceding claims, characterized in that that the contact area (207) of the channel element (201) is concave.

7. Method (100) according to one of the preceding claims, characterized in that that during the transfer (105) of the material in the at least one contact area (207) the laser (214) is moved along an asymmetric curve.

8. Method (100) according to one of the preceding claims, characterized in that that the channel element (201) is flexible when the channel element (201) is provided.

9. Method (100) according to one of the preceding claims, characterized in that R.417502 - 13 - that the channel element (201) remains clamped in a clamping device at one position throughout the entire procedure (100).

10. Method (100) according to any one of the preceding claims, characterized in that that the bipolar plate element (203) is positioned on the respective material accumulations (205), held down and then welded to the material accumulations (205), where the holding down is achieved by mechanical pressure and / or the application of a vacuum.

11. Functional group (200) for an electrochemical energy converter (300), wherein the functional group (200) is produced by a method (100) according to any one of claims 1 to 10.

12. Functional group (200) according to claim 11 , characterized by that the bipolar plate element (203) and / or the channel element (201) is made of stainless steel.

13. Functional group (200) according to claim 11 or 12, characterized by that the bipolar plate element (203) and / or the channel element (201) is made of titanium.

14. Electrochemical energy converter (300), wherein the electrochemical energy converter (300) comprises a number of functional groups (200) according to any one of claims 11 to 13.

15. Welding device (400) for the manufacture of a functional group (200) for an electrochemical energy converter (300), wherein the welding device (400) comprises: - a laser welding robot (401) and R.417502 - 14 - - a computing unit (403) configured to perform a method (100) according to any one of claims 1 to 10 using the laser welding robot (401).

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