Battery element for an electrochemical energy converter and method and welding device for manufacturing a battery element

Abstract

The invention relates to a cell element (100, 200) for an electrochemical energy converter. The cell element (100, 200) comprises a transport layer (101) and a bipolar plate (103), wherein the bipolar plate (103) comprises a conducting structure (105) for conducting an operating medium, wherein the conducting structure (105) has an at least partially embossed surface (107), wherein the transport layer (101) is directly welded together with the conducting structure (105) in the region of the embossed surface (107) by means of a platinum-free connection in the form of a plurality of weld points (109).

Description

Technical Field

[0001] According to the appended claims, the present invention relates to a battery element for an electrochemical energy converter, a method for manufacturing the battery element for the electrochemical energy converter, and a welding apparatus for manufacturing the battery element for the electrochemical energy converter. Background Technology

[0002] In particular, bipolar plates with noble metal coatings are used in electrolysis systems to reduce transition resistance and prevent the resistance from deteriorating due to the grown oxide layer during the service life of the bipolar plate.

[0003] This type of precious metal coating is costly and expensive to manufacture.

[0004] Furthermore, the bipolar plates are connected to the transport layer, such as a permeable sponge-like structure, via resistance welding. Laser welding is not used for this because it cannot reliably prevent localized gaps. Summary of the Invention

[0005] Within the framework of the proposed invention, a battery element for an electrochemical energy converter, a method for manufacturing the battery element, and a welding apparatus for manufacturing the battery element are provided. Further features and details of the invention are derived from the corresponding dependent claims, description, and drawings. Hereinafter, the features and details described in conjunction with the manufacturing method or welding apparatus according to the invention also apply to the battery element according to the invention, and vice versa, so that disclosures of various aspects of the invention may always be mutually referenced or mutually explanatory.

[0006] The proposed invention is particularly relevant to the possibility of providing a cost-effective battery element for electrochemical energy converters.

[0007] Therefore, according to the first aspect of the proposed invention, a battery element for an electrochemical energy converter, such as an electrolysis system or a fuel cell system, is proposed.

[0008] The proposed battery element includes a transport layer and a bipolar plate, wherein the bipolar plate includes a conductive structure for conducting the operating medium, wherein the conductive structure has at least a partially imprinted surface, and wherein the transport layer and the conductive structure are directly welded together in the region of the imprinted surface via platinum-free connections in the form of multiple welded joints.

[0009] The proposed battery element may be, for example, a half-cell of a battery in a stack used for an electrochemical energy converter.

[0010] In the context of the proposed invention, the transport layer should be understood as a porous transport layer or "Porous Transport Layer" (PTL).

[0011] In the context of the proposed invention, the embossed surface should be understood as a surface shaped according to a three-dimensional pattern or spatial pattern and comprising a first region and a second region, wherein the first region differs from the second region in its height position. Accordingly, for example, the first region first or only contacts a flat surface guided onto the embossed surface.

[0012] Furthermore, the imprinted surface is flexible or elastic, allowing it to deform but be pressed back to its initial position by spring force.

[0013] The proposed invention is based on a welded connection between the conductive structure of the bipolar plate, such as a channel system or imprint plate, and a porous transport layer.

[0014] Here, the welded connection forms a platinum-free connection that allows the bipolar plate to be directly connected to the transmission layer, i.e., without an intermediate layer.

[0015] Due to the deformability of the embossed surface of the conductive structure, a spring force is provided when the conductive structure is pressed onto the transport layer. This spring force presses the various raised areas of the conductive structure onto the transport layer, and thereby causes material tolerance compensation between the embossed surface, which is the first mating member, or the conductive structure, and the transport layer, which is the second mating member.

[0016] Due to the compensation of material tolerances, a safe or reliable contact is achieved between the conductive structure and the transmission layer, the so-called "local zero gap," which allows the conductive structure and the transmission layer to be welded together during the laser welding process.

[0017] Here, the welding of the conductive structure and the transmission layer results in a particularly low transition resistance between the conductive structure, or bipolar plate, and the transmission layer, so that precious metals, especially platinum coatings, can be omitted not only in the bipolar plate or the conductive structure but also in the transmission layer on the side facing the welding area.

[0018] The embossed surface may, for example, include multiple annular spring profiles.

[0019] Because of the multiple welding points provided according to the present invention and the manufacturing method according to the present invention, the noble metal layer, especially the platinum layer, used to reduce the contact resistance between the bipolar plate and the transmission layer can be omitted.

[0020] Accordingly, the transmission layer can be configured to have a noble metal layer only on the side opposite to the multiple welding points.

[0021] The conductive structure can be configured to include multiple channels constructed on the substrate structure of the bipolar plate, wherein multiple welding points are constructed on the bottom of at least one channel.

[0022] To construct a weld joint in a conductive structure including a channel, the imprinted surface may include multiple annular spring profiles formed on the bottom surface of the channel. For example, the spring profiles may have a spring height within the height variance of the conductive structure's surface. Specifically, the spring profiles may have a diameter less than 500 µm and a spring height greater than 50 µm.

[0023] For example, the embossed surface may include a large number of spring profiles constructed with a grid spacing of 1 mm or greater, so that current carrying capacity is ensured through corresponding welded joints between the conductive structure and the transmission layer.

[0024] Additionally, the conductive structure may include an imprinted plate soldered to a substrate structure of the bipolar plate, wherein the conductive structure includes a number of connecting elements that are soldered together with the substrate structure and with the transport layer via corresponding solder joints.

[0025] By using an embossing plate, for example, instead of ductile metal, to construct the conductive structure of a bipolar plate, a pre-defined connection geometry can be created that causes weld joints with the substrate structure of the bipolar plate and with the transport layer at pre-defined locations.

[0026] For this purpose, the imprint plate may include a number of connecting elements, such as arms or tabs, which extend in a predetermined height profile toward the bipolar plate substrate or toward the transport layer. Accordingly, each connecting element may be configured elastically or flexibly to cause compensation for material tolerances between the imprinted surface or conductive structure, which serves as a first mating element, and the transport layer, which serves as a second mating element, or the bipolar plate substrate, which serves as a third mating element.

[0027] By using an imprint plate as the conductive structure, especially on the substrate structure, on the side of the conductive structure facing the substrate structure, on the side of the conductive structure facing the transmission layer, and on the side of the transmission layer facing the conductive structure, the noble metal coating used to reduce the contact resistance between the bipolar plate and the conductive structure can be abandoned.

[0028] For example, the connecting elements can be configured to alternately move upwards and downwards, and to be offset at 90° or in a star shape. This offset arrangement of the connecting elements creates a three-dimensional frame that provides good rigidity to the battery elements for further processing, such as when connecting them to other battery elements to form a battery.

[0029] According to the second aspect, the proposed invention relates to a method for manufacturing a battery element for an electrochemical energy converter.

[0030] The proposed manufacturing method involves arranging a transmission layer and a bipolar plate conductive structure stacked one on top of the other, wherein the conductive structure has an imprinted surface.

[0031] Furthermore, the proposed manufacturing method includes pressing the conductive structure onto the transport layer in such a way that the imprinted surface is deformed and point contact between the conductive structure and the transport layer is ensured, and constructing multiple welding points at the points of contact between the imprinted surface and the transport layer so that the conductive structure and the transport layer are directly welded together via platinum-free connectors.

[0032] Multiple welding points can be constructed using tools such as scanners and fiber lasers, thus allowing for welding times of a few milliseconds for each weld point and a few seconds for each battery element. Correspondingly, the track speed during welding can be selected between 0.25 m / s and 0.75 m / s.

[0033] The proposed manufacturing method is based on an extrusion process in which the conductive structure is pressed or pressed onto the transport layer, thereby deforming the imprinted surface and ensuring point contact between the conductive structure and the transport layer.

[0034] To press the conductive structure onto the transmission layer, an automated clamping device or an operating robot can be used, for example. In particular, a pre-given weight can be placed on the conductive structure or bipolar plate to provide a clamping force that elastically compresses the connecting elements.

[0035] The conductive structure can be configured to include multiple channels constructed on the substrate structure of the bipolar plate, and multiple welding points constructed on the bottom of at least one channel.

[0036] By constructing the welded portion on the bottom of at least one channel, which serves as the lowest point of the conductive structure, the channel, or the bottom of the channel itself, can function as a spring element and can be altered in its cross-section, for example, by compression. Alternatively or additionally, a spring element can be embossed in the bottom of the channel, such that the bottom has a varying height profile and contacts the transport layer only at local minima, to construct the welded portion.

[0037] Alternatively, the conductive structure may include an imprint plate, which forms a large number of connecting elements. A first number of connecting elements are welded to the substrate structure of the bipolar plate, and a second number of connecting elements are welded to the transmission layer. Each connecting element has a rounded contact area, and the connecting elements are spot-welded on the contact area.

[0038] The rounded contact area serves two purposes: firstly, it predefines the geometry of the welding area, and secondly, it ensures reliable contact between the conductive structure and the transmission layer or substrate structure.

[0039] It can also be configured to automatically construct each welding part with the help of a laser welding robot, wherein the laser welding robot determines the position of the welding part based on the image obtained by the optical sensor of the surface to be imprinted and the image recognition algorithm, wherein the image recognition algorithm determines the position of the welding part at such point that the surface to be imprinted contacts the transfer layer.

[0040] To select points for constructing weld joints, an automatic image recognition system can be used. This system, for example, identifies local minima on a surface and selects these minima as points for constructing weld joints. Such an automatic image recognition system dynamically compensates for tolerances when contact occurs between the conductive structure and the transport layer or substrate structure.

[0041] It can also be set up to automatically construct each welding part with the help of a laser welding robot, wherein the laser welding robot constructs the welding part in a fixed, pre-defined position.

[0042] In particular, when using an imprint plate as a conductive structure, the positions of each welding part can be precisely pre-defined, so that these positions can be stored in memory and provided to the laser welding robot.

[0043] According to the third aspect, the proposed invention relates to a welding apparatus for manufacturing battery elements for electrochemical energy converters.

[0044] The proposed welding apparatus includes a laser welding robot and a computing unit configured in a possible configuration for executing the proposed manufacturing method.

[0045] In the context of the proposed invention, a computing unit should be understood as a computer, processor, control device, or any other programmable circuit.

[0046] Because laser welding robots perform contactless welding, the risk of battery poisoning due to metal ion transfer is minimized.

[0047] The welding apparatus may be configured to have surfaces made of titanium in various regions where it contacts the transport layer and / or conductive structure.

[0048] Battery element poisoning due to metal ion transfer is prevented by using surfaces made of titanium or titanium element in various regions where the welding device contacts the transport layer and / or conductive structure.

[0049] The advantages described in detail regarding the battery element for an electrochemical energy converter according to the first aspect of the present invention also apply to the manufacturing method for manufacturing the battery element for an electrochemical energy converter according to the second aspect of the present invention and the welding apparatus for manufacturing the battery element for an electrochemical energy converter according to the third aspect of the present invention.

[0050] Other advantages, features, and details of the invention will become apparent from the following description, in which embodiments of the invention are described in detail with reference to the accompanying drawings. Herein, the features mentioned in the claims and the description are substantially important to the invention, individually or in any combination. Attached Figure Description

[0051] The attached figures schematically illustrate: Figure 1 Based on the schematic diagram of the configuration of existing battery elements, Figure 2 First view of one possible configuration of the proposed battery element. Figure 3 :according to Figure 2 A second view of the battery components. Figure 4 : A first view of another possible configuration of the proposed battery element. Figure 5 :according to Figure 4 A second view of the battery components. Figure 6 One possible configuration of the proposed manufacturing method. Figure 7 One possible configuration of the proposed welding apparatus, and Figure 8 Used according to Figure 7 One possible configuration of the clamping component of the welding device. Detailed Implementation

[0052] exist Figure 1 The image shows a battery element 1000 according to the prior art.

[0053] The battery element 1000 includes a bipolar plate 1100 and a transport layer 1200. A first noble metal layer 1110 is disposed on the bipolar plate. The transport layer includes a second noble metal layer 1210 and a third noble metal layer 1220 on a porous structure 1230.

[0054] Accordingly, the battery element 1000 includes three noble metal layers 1110, 1210 and 1220.

[0055] These three precious metal layers 1110, 1210 and 1220 are necessary because the bipolar plate 1100 is welded over a large area in region 1230 onto the transport layer 1200 via resistance welding.

[0056] exist Figure 2 The image shows a battery element 100. The battery element 100 includes a transport layer 101 and a bipolar plate 103.

[0057] The bipolar plate 103 includes a conductive structure 105 for conducting the operating medium.

[0058] The conductive structure 105 further includes at least a partially imprinted surface 107.

[0059] The transport layer 101 and the conductive structure 105 are directly welded together in the region of the embossed surface 107 via platinum-free connectors in the form of multiple welded parts 109.

[0060] The battery element 100 has an optional noble metal layer 111 only on the side of the transmission layer 101 opposite to the plurality of solder sites 109.

[0061] Accordingly, battery element 100 has two fewer precious metal layers than battery element 1000 according to the prior art.

[0062] exist Figure 3 As can be seen, the conductive structure 105 constructs a large number of channels 113, and at the bottom 115 of each of these channels, there are welding parts 109 in the form of welding points.

[0063] To provide the welding area 109, as indicated by arrow 119, the bipolar plate 103 is pressed onto the transmission layer 101, such that the local minimum, i.e., a particularly deep region of the imprinted surface 107, can contact the transmission layer 101 and be connected to the transmission layer by a laser welding process.

[0064] Here, the imprinted surface 107 is elastically configured such that when the imprinted surface 107 is pressed onto the transport layer 101, the material tolerances of the transport layer 101 and the bipolar plate 103 are compensated.

[0065] exist Figure 4 The diagram shows a cross-section through another battery element 200. Here, the bipolar plate 103 includes an imprinted plate 121, which forms an elastic or flexible connecting element 123. Accordingly, the imprinted plate 121 is welded to the bipolar plate 103 via a first connecting element 123a and to the transport layer 101 via a second connecting element 123b.

[0066] For safe and simple spot welding, the connecting element 123 is rounded or spherical at its connection point before welding.

[0067] exist Figure 5 The battery element 200 is shown in a top view, in which it can be seen that the connecting elements 123 are arranged in a radially staggered group around a central point.

[0068] The connecting element is welded to the transport layer 101 made of sintered titanium at the welding point 109.

[0069] exist Figure 6 The diagram shows the materials used for manufacturing according to... Figure 1 Method 300 for manufacturing a battery element 100 for an electrochemical energy converter.

[0070] Manufacturing method 300 includes an arrangement step 301 in which a transmission layer and a bipolar plate are arranged stacked one on top of the other, wherein the transmission structure has an imprinted surface.

[0071] Furthermore, the manufacturing method 300 includes an extrusion step 303 in which the conductive structure is pressed onto the transport layer such that the imprinted surface is deformed and point contact is ensured between the conductive structure and the transport layer.

[0072] In addition, the manufacturing method 300 includes a construction step 305 in which a plurality of welding points are constructed at the points where the imprinted surface contacts the transport layer for welding the conductive structure to the transport layer.

[0073] Here, the transport layer has a noble metal layer only on the side away from the multiple welding sites.

[0074] exist Figure 7 The diagram shows the materials used for manufacturing according to... Figure 1 A welding device 400 for a battery element 100 used in an electrochemical energy converter.

[0075] The welding apparatus 400 includes a laser welding robot 401 and a computing unit 403 configured to perform operations based on... Figure 6 Manufacturing method 300.

[0076] To clamp the connecting elements, the welding device may include multiple [parts / equipments]. Figure 8 The clamping elements 405 shown are configured to bend or clamp the connecting element 123. Accordingly, the clamping elements 405 may be made of titanium or include contact areas made of titanium to prevent poisoning of the transport layer 101 by metal ions.

Claims

1. Battery elements (100, 200) for electrochemical energy converters. in, The battery elements (100, 200) include: - Transport layer (101). -Bipolar plate (103). The bipolar plate (103) includes a conductive structure (105) for conducting the operating medium. The conductive structure (105) has at least a partially imprinted surface (107). The transport layer (101) and the conductive structure (105) are directly welded together in the region of the embossed surface (107) via a platinum-free connection in the form of multiple welded parts (109).

2. The battery element (100, 200) according to claim 1, characterized in that, The conductive structure (105) includes a plurality of channels (113) constructed on the substrate structure of the bipolar plate (101). The plurality of welded portions (109) are constructed on the bottom (115) of at least one channel (113).

3. The battery element (100, 200) according to claim 1 or 2, characterized in that, The conductive structure (105) includes an imprint plate (121) which is welded to the substrate structure of the bipolar plate (103). The conductive structure (105) includes a number of connecting elements (123) which are welded together with the substrate structure and the transmission layer (101) via corresponding welding points (109).

4. A manufacturing method (300) for manufacturing battery elements (100, 200) for use in electrochemical energy converters. in, The manufacturing method (300) includes: - The conductive structure (105) of the transmission layer (101) and the bipolar plate (103) is arranged stacked on top of each other (301), wherein the conductive structure (105) has an imprinted surface (107). - The conductive structure (105) is pressed (303) onto the transport layer (101), causing the imprinted surface (107) to deform and ensuring point contact between the conductive structure (105) and the transport layer (101). - A plurality of welding points (109) are constructed (305) at the point where the embossed surface (107) contacts the transport layer (101) to directly weld the conductive structure (105) and the transport layer (101) together via a platinum-free connection.

5. The manufacturing method (300) according to claim 4, characterized in that, The conductive structure (105) includes a plurality of channels (113) constructed on the substrate structure of the bipolar plate (103), and the plurality of welding points (109) are constructed on the bottom (115) of at least one channel (113).

6. The manufacturing method (300) according to claim 4 or 5, characterized in that, The conductive structure (105) includes an embossed plate (121) which forms a plurality of connecting elements (123). In this configuration, a first number of connecting elements (123a) are welded to the substrate structure of the bipolar plate (103), and a second number of connecting elements (123b) are welded to the transmission layer (101). Each connecting element (123) has a rounded contact area, and the connecting element (123) is spot-welded on the contact area.

7. The manufacturing method (300) according to any one of claims 4 to 6, characterized in that, The laser welding robot (401) automatically constructs each welding part (109), wherein the laser welding robot (401) determines the position of the welding part based on the image of the imprinted surface (107) obtained by an optical sensor and an image recognition algorithm. The image recognition algorithm identifies the location of the welding point as such that the imprinted surface (107) is in contact with the transport layer (101) at the point.

8. The manufacturing method (300) according to any one of claims 4 to 6, characterized in that, The laser welding robot (401) automatically constructs each welding part (109), wherein the laser welding robot (401) constructs the welding part (109) at a fixed, predetermined position.

9. Welding apparatus (400) for manufacturing battery elements (100, 200) for electrochemical energy converters. in, The welding apparatus (400) includes: - Laser welding robot (401). - A computing unit (403) configured to perform the manufacturing method (300) according to any one of claims 4 to 8.

10. The welding apparatus (400) according to claim 9, characterized in that, The welding device (400) has a surface made of titanium in each of the following regions: in which the welding device (400) is in contact with the transport layer (101) and / or the conductive structure (105).

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