Apparatus and method for additive manufacturing of multi-material assemblies on a platform integrated in a common machine table, in particular electrochemical cells

Abstract

A method for additive manufacturing components, particularly electrochemical cells, specifies the construction of components (4) layer by layer from powder material using a 3D printing apparatus (9) on platforms (3) integrated in a common machine tool table (2) and separated from each other, wherein these platforms (3) are simultaneously and sequentially height-adjusted relative to the working surface (18) of the machine tool table (2). Furthermore, an apparatus (1) for additive manufacturing components (4,5,6), particularly components of electrochemical cells (16), is provided, especially for carrying out the method.

Description

[0001] This invention relates to a method for additive manufacturing components, particularly electrochemical cells. Furthermore, the invention also relates to an apparatus suitable for carrying out this method.

[0002] An apparatus for generative manufacturing of components is known, for example, from DE 10 2019 201 494 A1. This known apparatus uses different material powders in component manufacturing, which may differ from one another in their physical and chemical properties and / or composition. The planar coated material powder may completely or partially fill the component platform. According to the teachings of DE 10 2019 201494 A1, selective irradiation of the powder layer can be performed by laser, ion, or electron beams, wherein the irradiation section and the coating section are alternated.

[0003] An apparatus for additive manufacturing of three-dimensional components, described in DE 10 2017 208 132 A1, includes multiple devices arranged above a build platform, each having at least three arms articulated to a processing head, and the lengths of these arms are adjustable. A supply channel for conveying a suspension or liquid suitable for printing extends through at least one arm. According to the apparatus of DE 10 2017 208 132 A1, the arrangement and control of the individual devices allow multiple devices to be used simultaneously to manufacture one or more components.

[0004] DE 10 2016 204 462 A1 describes a method for additive manufacturing components and a support plate for supporting the additively manufactured components. It is envisioned that a blank component is first additively manufactured on the support plate. Subsequently, at least a portion of the support plate is clamped in a machine tool. According to DE 10 2016 204 462 A1, it is further envisioned that a separate machining step is performed on the blank component on the machine tool.

[0005] DE 10 2015 105 568 A1 relates to the additive manufacturing of flow fields in fuel cells. In this process, flow field channels are formed, particularly by additively forming channel walls on a plate. This plate can, for example, be a gas diffusion layer.

[0006] A bipolar plate disclosed in EP 4113672 A1 should be entirely fabricated by additive manufacturing. In the additive manufacturing process, it is envisioned that a filled plastic matrix, a filled electrode matrix, or an unfilled plastic matrix are added sequentially, with a sealing edge formed by the unfilled plastic matrix. Conversely, the proton exchange membrane and gas diffusion layer should be used as pre-fabricated, separately manufactured components.

[0007] CN 111463449 A describes steps for manufacturing a metal powder used in the fabrication of bipolar plates. Accordingly, the metal is processed by grinding at a temperature of 50°C to 500°C over a period of several hours.

[0008] Documents US 11,260,586 B2 and DE 10 2017 120 750 B4 describe different apparatuses and methods for manufacturing components via 3D multimaterial printing. Also relevant to the topic of multimaterial 3D printing are WO 2019 / 185626 A1, WO 2018 / 059833 A1, and WO 2019 / 185466 A1.

[0009] The objective of this invention is to further develop, compared with the prior art, an additive manufacturing method that can be used to manufacture components, particularly components for manufacturing electrochemical cells (e.g., fuel cells, redox flow batteries, battery cells, or electrolyzers), wherein the aim is to achieve particularly high manufacturing flexibility without making the operation too complex.

[0010] According to the present invention, this task is solved by the method for additive manufacturing components, particularly electrochemical cells, according to claim 1. To implement this method, an apparatus having the features of claim 8 is applicable. The embodiments and advantages of the invention set forth below in relation to the apparatus of this application also apply to the manufacturing method, and vice versa.

[0011] Electrochemical battery components, especially fuel cells, preferably polymer electrolyte fuel cells or electrolyzers manufactured by this method, are preferably components having a polymer electrolyte membrane and / or for water electrolysis, or redox flow batteries or battery cells.

[0012] This manufacturing method specifies the use of a 3D printing apparatus that uses powdered material as the raw material for 3D printing, i.e., generative manufacturing. Components are built layer-by-layer using multi-material 3D printing on separate platforms integrated into a common machine tool table. Multi-material 3D printing here refers to a 3D printing method that uses at least two different materials for layer construction. Theoretically, there is no upper limit to the number of different 3D printing materials. For example, additive manufacturing can use three, four, or more different 3D printing materials. These can be, for example, plastics or ceramic or metal-based materials. In any case, during the 3D printing process, the platform's height is adjusted progressively, i.e., sequentially, simultaneously, relative to the machine tool table's working surface. This means that the platform is set at a uniform height at each step. During the construction of components from individual layers, the spaces between the platforms remain free of powdered material, i.e., 3D printing material.

[0013] Regardless of the quantity of different 3D printing materials, at least one generatively formed layer contains multiple materials. Other layers can be constructed in a homogeneous material manner. In any case, at least a portion of the layer's volumetric region contains multiple workpieces generated on different platforms. Simultaneously, the volumetric region between these platforms and the workpieces remains empty throughout the manufacturing process. This enables faster manufacturing compared to conventional methods and offers significant variability in manufacturing due to its multi-material prototyping characteristics.

[0014] Depending on the possible process variations, during component construction, the platform is lowered below the working surface. Here, each new layer of the component can be built directly above the working surface of the machine tool table. After component forming is complete, i.e., after the platform is at its maximum lowering, the component can be raised via a lifting device connected to the platform. The upper surface of the platform at its maximum elevation is specifically flush with the working surface of the machine tool table. All platforms can be mechanically connected to a vertically adjustable element of the lifting device. Alternatively, the platform can be adjusted, for example, by hydraulic adjustment or by a single electromechanically driven electronic synchronous adjustment.

[0015] As a powdered 3D printing material, uncured material residues from the 3D printing process can be reused. This is particularly suitable for 3D printing materials that may be located next to a partially formed component on the same platform at different manufacturing stages. On a single platform, a single workpiece or multiple workpieces that do not necessarily need to be identical can be built layer by layer. To minimize excess powdered 3D printing material, a filler powder can be used, which can be easily processed and reused after de-powdering. Such powder can fill the gaps formed between workpieces generated on the same platform, or the voids between different platforms. In its simplest case, the processing of powdered material is carried out as a sieving process, thereby removing larger particles, especially those formed due to welding, from the powder.

[0016] Each platform may have a rectangular shape, but not all platforms need to be exactly the same. Depending on the geometry of the workpiece to be manufactured, platforms with curved profiles in the top view can be used. In specific cases, hexagonal or other planar shapes of the platforms can also effectively utilize space while adapting to the workpiece geometry. Platforms can be configured to be interchangeable and can be tool-free for replacement.

[0017] According to one possible process variation, regardless of the platform's planar shape, a layer of the first component is constructed on the first platform in a homogeneous manner, while the same layer of the second component is also constructed on the second platform in a homogeneous manner, but using a different material than the first component. Alternatively, at least one layer of the same component can be constructed in a heterogeneous manner, i.e., in multi-material 3D printing. In this case, for example, similar components can be constructed on separate platforms using multi-material 3D printing. It is also possible to construct different types of components simultaneously on the same platform.

[0018] Components produced generatively via multi-material 3D printing include, for example, components of electrochemical cells, such as fuel cells or electrolyzers. Such components may include, in particular, electrode plates, separators, bipolar plates with flow-through cooling channels, and open-pore gas diffusion layers (GDLs) / open-pore transport layers (PTLs). In subsequent operating cells containing additively manufactured parts, such as fuel cells or electrolyzers, it is preferable to have gas diffusion layers / porous transport layers on both the cathode and anode sides, which may be constructed in the same manner or differ from each other. This generative manufacturing method can be implemented such that a uniform gas diffusion layer / porous transport layer is generated in a common process step, or open-pore gas diffusion layers / porous transport layers on the cathode and anode sides are generated differently. In either case, the gas diffusion layer / porous transport layer may be generated together with at least one bipolar plate, electrode plate, separator, or part thereof as an integral component. The composition of bipolar plates, electrode plates, or separators is usually different from that of the open gas diffusion layer / open transport layer connected to them and belonging to the same monolithic 3D multimaterial printing component.

[0019] Generally, multi-material 3D printing can combine materials with different metal contents for generative manufacturing. For example, one material may be a pure metal except for process-induced impurities, while another material to be processed in the same manufacturing process may have a low or no metal content. The different materials can be applied to the platform in powder form, so that at any point in the manufacturing process, it is not necessary to seamlessly fill the entire working area of ​​the machine table with these materials in one layer. The remaining areas of the layer can either remain empty or be filled with the aforementioned filler powder.

[0020] The present invention relates to additive manufacturing components, particularly electrochemical cells, and especially to an apparatus for carrying out the method of the invention, comprising a plurality of platforms mounted in a common machine tool table, separated from each other, with adjustable height, and lowerable below the working surface of the machine tool table, and at least one printhead designed for simultaneous, layer-by-layer fabrication of components allocated to each platform in multi-material 3D printing.

[0021] The lifting device used to lower and raise the platform can be designed to lower the components being manufactured at the same time to a position where they—at least except for the topmost layer—are below the working surface of the machine tool table.

[0022] The apparatus of the present invention preferably manufactures electrochemical battery components, particularly components of fuel cells (preferably polymer electrolyte fuel cells), electrolyzers (preferably for water electrolysis), or redox flow batteries. Optionally, the apparatus—regardless of the type of workpiece—is designed to simultaneously process 3D printing materials with different metal contents. The curing of the 3D printing materials used can be performed, in particular, by laser in a manner known per se.

[0023] One possible structural configuration envisions using a single printhead to deposit material layer by layer across all platforms. A greater number of printheads can also be used. Similarly, multiple laser processing heads can be used, such as two, three, four, or even more than ten. In all cases, the movable parts of the apparatus for multi-material 3D printing can be adjusted using mechanisms already known (e.g., screw drives in the form of ball screws). Linear electric direct drive can also be employed for the parts (e.g., the processing head). Additionally, the multi-material 3D printing apparatus may include monitoring devices, such as in the form of an optical system, or a system that can detect the electrical properties of the workpiece during or immediately after additive manufacturing.

[0024] An embodiment of the present invention will be further described below with reference to the accompanying drawings. Parts of the drawings are schematically shown in the drawings: Figure 1 A single component of an apparatus for manufacturing components, viewed from a top view, comprising multiple workpieces undergoing an additive manufacturing process. Figure 2 A schematic cross-sectional view shows a stack of electrochemical cells, including multiple components manufactured using the apparatus shown in the figure. Figure 3 Figure 1 shows a schematic side view of the device. Figure 4 A schematic cross-sectional view partially illustrates an additively manufactured component produced using the apparatus shown in Figure 1, which is configured as a multi-material component. Figure 5 - 9 Figure 1 shows the device and several components in additive manufacturing at different manufacturing stages. Figure 10 Figure 1 shows the apparatus and the components manufactured in the steps of Figures 5 to 9.

[0025] An apparatus for additive manufacturing of components, here for an electrochemical cell, indicated by reference numeral 1, is a production apparatus configured as a multi-material 3D printing device and includes a machine table 2 on which multiple platforms 3 are arranged at the same height, which in this example appear as strips in the top view. The component 4 manufactured by the production apparatus 1, which will be further described later, is used for a battery stack, also referred to as a stack, consisting of electrochemical cells 16 and indicated by reference numeral 15.

[0026] The battery stack 15 includes multiple electrochemical cells 16, such as fuel cells or electrolytic cells, located between two end plates 8. Between each pair of cells 16, a bipolar plate 5 is disposed, with half of the bipolar plate belonging to two adjacent half-cells 17. Each cell 16 consists of two half-cells 17 separated from each other by a proton-permeable membrane 7. The bipolar plate 5 separates one half-cell 17 of the first electrochemical cell 16 from one half-cell 17 of the other electrochemical cell 16. Within the space between the membrane 7 and the bipolar plate 5, at least one so-called open-pore gas diffusion layer 6 exists for the fuel cell, or at least one so-called open-pore transport layer 6 exists for the electrolytic cell. The gas diffusion layer / open-pore transport layer 6 and the bipolar plate 5 together constitute component 4, i.e., the workpiece, which is manufactured in a production manner in the production apparatus 1.

[0027] For a further explanation of the structure of production apparatus 1, please refer to Figure 3. Subsequently, a 3D printing device 9, which constitutes the core component of production apparatus 1, is used to generate the workpiece 4, i.e., the multi-material assembly.

[0028] The printhead 10, designated 10, allows for the selective use of two different materials with varying metal contents for printing. To this end, in the schematic shown in Figure 3, the printhead 10 internally comprises two volumes 11 and 12, each connected to a storage container 13 and 14 for a different material. Alternatively, a separate printhead 10 can be provided for each material.

[0029] The print head 10 can achieve multi-axis movement using various known mechanisms, such as ball screw drives. Powdered material stored in the storage containers 13 and 14 can be precisely placed onto the respective platforms 3 via the print head 10. Unlike conventional methods (where an entire layer of the 3D printing device is filled with powdered material), the print head 10 has the ability to lay different materials on defined planar areas on the same platform 3. Planar areas of the platform 3 where the layer for building the workpiece 4 does not need to be constructed can either remain free of 3D printing material or be filled with a filler powder. In either case, it is not necessary to place 3D printing material between the platforms 3. Conversely, these areas can also remain free of any material or be filled with a filler powder that can be easily reused.

[0030] The layered structure of component 4 is shown in Figure 4. Here, the first layer S1 is entirely composed of the first material, while the layer S2 above it, as shown in Figure 4, is partially composed of the first material and partially of the second material. In this example, the first material is the material of the bipolar plate 5, and the second material is the material of the gas diffusion layer / aperture transport layer 6. The materials of the different components 5 and 6 of component 4 differ from each other in terms of their metal content.

[0031] In the structure shown in Figure 4, the gas diffusion layer / aperture transport layer 6 is located above the bipolar plate 5. This structure can be combined with another structure that forms a mirror image of it, wherein the mirror plane is horizontal, i.e., orthogonal to the drawing plane. In the completed stack 15, one of the structures is connected to the cathode side, and the other structure is connected to the anode side. For example, the gas diffusion layer / aperture transport layer 6 on the cathode side is located above the bipolar plate 5 shown in Figure 2, while the gas diffusion layer / aperture transport layer 6 on the anode side is located below the same bipolar plate 5. The regions of the gas diffusion layer / aperture transport layer 6 and the corresponding bipolar plate 5 are constructed on different platforms 3 of the production apparatus 1 in the same process, and the differences between the two are formed during the generative manufacturing process. If it is necessary to test the characteristics of the workpiece 4, such as electrical characteristics or characteristics involving dielectric permeability, the component 4 still located on the platform 3, the individual component 4 removed from the production apparatus 1, or the component 4 loaded into the stack 15 can be tested accordingly. Similarly, this can also be done when stack 2 is a stack of other electrochemical cells 16 (e.g., cell units or redox flow cells).

[0032] Figures 5 through 10 illustrate the various steps of the generative manufacturing of component 4. The upper surface of the machine table 2 forms a working surface 18. As shown in Figures 5 through 10, platform 3 can be positioned such that its upper surface is on the same plane as the working surface 18. From this plane, platform 3 can be lowered, with each platform 3 positioned in a recess 21 in the machine table 2. For this purpose, a lifting device, indicated by 18, is provided and mechanically connected to all platforms 3 in this example.

[0033] In the structure shown in Figure 5, each component 4 is in a partially completed state. During each manufacturing stage, the lifting device 18 adjusts the platform 3 to the same height and lowers it to such a degree that the upper surface of the component 4 lies within the plane of the working surface 18. Next to each component 4, uncured powder 22, i.e., 3D printing material, is visible, and this powder is located on the same platform 3. The gaps between the platforms 3, indicated by ZR, do not contain 3D printing material.

[0034] In the step shown in Figure 6, powder 22 is placed on platform 3, and thus also on component 4, while space ZR remains free of powder 22 in this step. Powder 22 extending beyond the working surface 18 is cured in the step shown in Figure 7, wherever necessary for constructing component 4, by laser radiation LS generated by laser 20.

[0035] Figure 8 shows the state of components 4 after the steps in Figure 7, i.e., they have grown a layer of S1, S2. Components 4 now extend beyond the working surface 18 and are still surrounded by uncured powder 22. In this state, as shown in Figure 9, components 4 are further lowered until their surfaces are once again at the level of the working surface 18.

[0036] The steps shown in Figures 5 through 9 are repeated until the additive manufacturing of component 4 is complete. Then, as shown in Figure 10, all platforms 3 are raised to such an extent that the upper edge of platform 3 is flush with the working surface 18, and component 4 can be removed from the machine table 2. After powder removal, component 4 is removed from the production unit manually or automatically; optionally, subsequent mechanical and / or chemical processing is performed after the additive manufacturing of component 4, which is formed as a multi-material 3D printed part.

[0037] Explanation of reference numerals in the attached figures 1. Production equipment, equipment for additive manufacturing components. 2 Machine tool table 3 platforms 4 components, workpiece 5 bipolar plates 6. Open-pore gas diffusion layer / open-pore transport layer 7. Membrane 8 end plates 9. Printing device 10 Printheads 11 Partial Volume 12-part volume 13 Storage containers 14 Storage containers 15 Battery stacks, stacked 16 Electrochemical Cells 17 half-cell 18 Working surfaces 19 Lifting device 20 lasers 21 Grooves 22 Powder, 3D Printing Material LS laser radiation S1, S2 layers Space between the two ZR platforms

Claims

1. A method for additive manufacturing of components, particularly electrochemical cell components, in, Component (4) is manufactured layer by layer from powder material using a 3D printing device (9) through multi-material 3D printing. The components are formed on a platform (3) that is integrated into a common machine tool table (2) and is separate from each other. These platforms (3) simultaneously and gradually adjust their height relative to the working surface (18) of the machine tool table (2). Furthermore, during the multi-material 3D printing process, the space (ZR) between the platforms (3) is kept free of powder material.

2. The method according to claim 1, characterized in that, The platform (3) is lowered below the working surface (18) during the component (4) construction process.

3. The method according to claim 2, characterized in that, Each new layer (S1, S2) component (4) is constructed directly above the working surface (18).

4. The method according to claim 3, characterized in that, After component (4) is formed, that is, after platform (3) is reduced to its maximum extent, The component (4) is lifted by a lifting device (19) connected to the platform (3).

5. The method according to any one of claims 1 to 4, characterized in that, A certain layer (S1, S2) of the first component (4) is constructed on the first platform (3) in a material homogeneous manner. The same layers (S1, S2) of the second component (4) are also constructed on the second platform (3) in a homogeneous manner. However, the materials used are different from those of the first component (4).

6. The method according to any one of claims 1 to 4, characterized in that, At least one layer (S1, S2) of the same component (4) is constructed in a material heterogeneous manner by materials with different metal contents.

7. The method according to any one of claims 1 to 6, characterized in that, Component (4) is a component of an electrochemical cell (16), particularly a component of a fuel cell or electrolyzer. Among them, in the common process steps of the platform (3) with highly consistent adjustment, In addition to the bipolar plate (5), open gas diffusion layers (6) or open transport layers (6) with different cathode and anode sides are also generated on the platform (3).

8. An apparatus (1) for additive manufacturing components (4, 5, 6), particularly for electrochemical cell (16) components, especially for a multi-material 3D printing apparatus for carrying out the method of any one of claims 1 to 7. This includes multiple platforms (3) mounted on a common machine tool table (2), which are separate from each other. The height can be adjusted simultaneously, and it can be lowered below the working surface (18) of the machine tool table (2). And at least one printhead (10) designed to synchronously produce layer by layer the components (4, 5, 6) assigned to each platform (3).

9. The apparatus according to claim 8, characterized in that, A lifting device (19) is provided for lowering the platform (3). The lifting device is designed to lower the synchronously manufactured components (4, 5, 6) to a position below the working surface (18) at least except for the uppermost layer (S2).

10. The apparatus according to claim 8 or 9, characterized in that, The device is designed to process 3D printing materials with different metal contents simultaneously. Furthermore, the same printhead (10) is designed to build materials layer by layer on all platforms (3).

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