Method for producing plate assemblies, plate assemblies, and corresponding electrochemical cells

Abstract

The present invention relates to the production of a plate assembly (2) for a stack (1) of an electrochemical cell (3), wherein plates (22, 22', 4) arranged parallel to each other are additively manufactured in a plane oriented perpendicular to the plates (22, 22', 4). The present invention also relates to an electrochemical cell, an electrochemical system in the form of an electrolytic cell, having a cell stack comprising two end plates, wherein at least one such plate assembly (2) and at least two polymer electrolyte membranes are disposed between the two end plates.

Description

Technical Field

[0001] The present invention relates to a method for producing a plate assembly of a stack of electrochemical cells using an additive manufacturing method. Furthermore, the present invention relates to a plate assembly for an electrochemical system comprising additively manufactured components. Finally, the present invention relates to an electrochemical cell, particularly an electrolytic cell.

Background Art

[0002] The generative production of components of a fuel cell stack or an electrolytic cell is basically known, for example, from German Patent Application Publication No. 102013108413. The manufacturing techniques mentioned here are laser, electron beam and vapor jet sintering. The production method should also be suitable for connecting the components of the cell stack.

[0003] International Publication No. 2023 / 021217 discloses an integrated method for producing a monolithic solid oxide cell (SOC) stack based on a single 3D printing system. The method according to International Publication No. 2023 / 021217 includes the production of various electrodes as well as electrolytes and intermediate layers. Similarly, housing components including insulating ceramic materials should be able to be additionally manufactured.

[0004] U.S. Patent Application Publication No. 2015 / 0290860 addresses the shape of nozzles for the additive production of components of an electrochemical system. Nozzle shapes different from circular ones have been proposed. This should enable the construction of composites of various flat components having channels for the passage of fuel or air, among other things.

[0005] U.S. Patent Application Publication 2008 / 0008826 also deals with the additive manufacturing of fuel cell components. In this manufacturing process, powder layers are solidified by laser sintering for the purpose of producing regions with different porosity. At least two layers of the assembly described in U.S. Patent Application Publication 2008 / 0008826 have different compositions and different thicknesses.

[0006] A method for producing an electrochemical cell device described in German Patent Application Publication No. 102018100772 provides functional layers produced on a cell carrier by direct material deposition. The cell carrier is a cell separator that forms the outer boundary of the electrochemical cell. The cell carrier can be produced from stainless steel and may have a corrosion protection layer. The functional layers sequentially stacked on the cell carrier are configured in particular as a gas distribution layer and a catalyst layer. According to German Patent Application Publication No. 102018100772, it should also be possible to produce electrochemical functional layers having a gradient, the gradient being carried out with respect to the geometric design and / or material, and the gradient occurring in the stacking direction and / or transverse direction with respect to the stacking direction.

[0007] According to German Patent Application Publication No. 102014226567, at least a portion of the bipolar plate of a fuel cell system is produced using a generative lamination method. To form a flow field, the material should be selectively applied only to the protrusions of the bipolar plate's base plate topology. In this way, contact areas made from, for example, titanium, nickel, or chromium are produced.

[0008] U.S. Patent Application Publication No. 2005 / 0221150 deals with the additive manufacturing of honeycomb structures for electrochemical cells. In this manner, metal powders containing the elements nickel and chromium are solidified by laser sintering. In addition, the metal layer may contain bronze as a binder. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The present invention aims to further develop the production of layered cells in electrochemical systems compared to the cited prior art, and in particular to enable the simultaneous production of multiple cell components. [Means for solving the problem]

[0010] This objective is achieved, according to the present invention, by the method for producing a plate assembly of an electrochemical cell, in particular an electrolytic cell or fuel cell stack, as described in claim 1. This objective is also achieved by a plate assembly having the features of claim 7 and an electrochemical cell having the features of claim 14. Any embodiments and advantages of the present invention described below in relation to a plate assembly or an entire electrochemical system also apply to the production method according to this application, and vice versa.

[0011] A method for producing a plate assembly for an electrochemical cell stack is characterized in that plates arranged parallel to each other are produced in addition on a plane that is aligned perpendicular to the plates.

[0012] Simply put, this means that each individual plate in a plate assembly is like a slice cut from a tree with a saw, and cut across the grain. In contrast, plates made from a cell stack or other stack using conventional 3D printing methods are like a standard board that has been sawn longitudinally along the trunk of a tree, for the image to be reused.

[0013] Upright additive manufacturing of plates, where each plate is constructed upright on the 3D printing platform starting from a narrow plate edge, allows for the creation of particularly delicate and complex structures that would be impossible if plates were manufactured on the 3D printing platform starting from a large horizontal plate side. For example, recesses for forming overhangs can only be produced with low quality in 3D printing when plates are stacked one after another, i.e., horizontally, because when the powder material is melted by the laser, the laser beam reaches an undesirable depth, and a structure similar to the ceiling of a stalactite is formed on the resulting recess. The larger the desired overhang length and the smaller the rising angle of the solidified structure formed, the lower the print quality.

[0014] If the plates of a plate assembly are produced overlapping each other, the entire underside will form a 90° overhang toward the print base. This would require support from a support structure, which would have to be mechanically removed after 3D printing. The surface with the remainder of the support structure would not be suitable as a contact surface with the electrochemical cell membrane. In addition, the thermal residual stress in 3D printing is so large that such a support structure would not be mechanically retained.

[0015] At the same time, as print quality decreases, the load-bearing capacity of 3D printed structures under pressure decreases in recessed areas, which is unacceptable for safety reasons, especially in the case of electrochemical cells that operate under high operating pressure, such as electrolytic cells. Such problems can be avoided when constructing plate assemblies according to the method of the present invention, enabling the production of a wide range of high-quality 3D printed structures.

[0016] In addition, horizontal positioning of plate assemblies during 3D printing is uneconomical because, in contrast to vertical printing processes, due to spatial constraints, far fewer or even just one plate assembly can be printed simultaneously based on a print base of the same dimensions.

[0017] This has been found to be particularly significant when the plate assembly is formed integrally from plates arranged parallel to each other. However, to save assembly effort and reduce contact resistance when assembling electrochemical cells, at least two plates should be formed integrally.

[0018] The plate assembly according to the present invention comprises a plurality of integrally formed, additively manufactured, parallel, and not necessarily identical plates, with the 3D printed layer aligned orthogonally to these plates. A special advantage of the plate assembly is that there is a close material bond between the plates, eliminating the electrical losses that occur in the areas of contact between plates that are simply pressed against each other in conventional electrochemical cells. This enables the electrochemical cell to operate with high efficiency.

[0019] For example, the first type of plate can be constructed as a bipolar plate. The term "bipolar plate" is used here in the same way as the structure in a conventional electrochemical cell. However, a complete plate assembly can provide the electrical properties of such a bipolar plate because it is conductive overall and made of metallic material. Similarly, a plate constructed in this way as a 3D printed object can function as a porous transport layer in an electrochemical cell. In such cases, it is possible to construct a multilayer transport layer, in particular, where each layer has different porosity and / or thickness. During the additive manufacturing of the porous transport layer, the different layers for constructing the plate assembly appear as adjacent strips within the layer currently being constructed by 3D printing.

[0020] The additive manufacturing method according to the present invention can be configured particularly efficiently by simultaneously stacking multiple identical parallel plate groups on a 3D printing platform, each containing multiple different plates and positioned perpendicular to the 3D printing platform. Individual plate groups produced together in a printing batch can be assembled into a single cell stack or distributed across several cell stacks after additive manufacturing. Each plate assembly, also called a sandwich, can be de-powdered after being separated from the construction platform, i.e., the 3D printing platform. This can be followed by heat treatment. Optionally, the external surface of the plate assembly can be finished by grinding. Additional straightening processes can also be performed. Similarly, a conductive coating made from a precious metal, such as platinum, can be applied to at least a portion of one or both sides of the plate assembly. This makes it possible to coat a second layer outside the porous transport layer. The coating is preferably applied using PVD or PACVD methods. Optionally, before the coating process, plasma etching of the surface to be coated can be performed to remove any existing oxide layers, thereby ensuring good adhesion and electrical contact of the coating to the plate assembly. By providing a coating that includes pre-plasma etching of the existing oxide layer, the electrical resistance of the entire plate assembly, i.e., from polymer electrolyte film to polymer electrolyte film, can be achieved as if it were made entirely of gold.

[0021] According to various possible embodiments, the multiple plates to be attributed to the plate assembly are formed as porous layers of a sandwich-type plate assembly. In particular, the porous layers can be multilayer porous transport layers on the cathode or anode side of a subsequent electrochemical cell. In this case, the first layer of each porous transport layer is constructed to have particularly large pores, while the second layer of each porous transport layer is preferably constructed to be relatively thin and have fine pores. The latter second layer of each porous transport layer preferably forms the outer surface of the plate assembly in at least a portion of the plate assembly. The pores of the microporous second layer preferably have a diameter of less than 80 μm, particularly in the range of 60 to 80 μm, while the pores or channels of the coarse-porous first layer preferably have a diameter of greater than 0.2 mm, particularly greater than 1 mm.

[0022] The second microporous layer of each porous transport layer preferably has a thickness of less than 0.2 mm, and the first coarse-porous layer of each porous transport layer preferably has a thickness of more than 0.5 mm.

[0023] The openings representing the pores of each second layer are optionally introduced later during additive manufacturing into the porous transport layer, particularly into the outer microporous second layer. In the latter case, additional fine porosity can be created, for example, by plasma drilling, laser drilling, or etching. Essentially, the pores in the porous transport layer can have either a geometrically defined shape or an undefined shape with a probabilistic size distribution, in either case permeability, i.e., open porosity, is provided to the coarse-porous first layer and the microporous second layer.

[0024] In the case of the first macroporous first layer, for example, a defined shape in the form of a lattice is considered. During the operation of the electrochemical cell, this lattice transmits forces between adjacent cell components and at the same time provides a free flow cross-section for the operating medium. The same applies to the microporous second layer, which is in contact with the lattice and, in particular, provides a flat support surface for components adjacent to the second layer in the electrochemical cell, such as a proton-permeable polymer electrolyte membrane of the electrochemical cell or a gas diffusion layer made of carbon paper or carbon fleece. Due to 3D printing, the flat support surface has a roughness that results in an increase in the surface area of this support surface. Here, it has been found that a roughness in the range of Rz16 is effective.

[0025] Subsequently, the membrane is applied to the plate assembly either before or during the assembly of the entire electrochemical cell stack. In contrast to the membrane, the microporous second layer of the additionally produced plate assembly is adapted to the dominant conditions and the properties of the membrane during the operation of the electrochemical cell with regard to its electrical and corrosion properties. The membrane is arranged in the cell stack in a plane that intersects perpendicularly to the 3D printing plane that is continuously produced during additive manufacturing.

[0026] In contrast to the porous transport layer of the plate assembly, the bipolar plate, which is also part of the plate assembly, can form channels for the cooling medium that is separated from the operating medium of the electrochemical system. The cooling medium is particularly water. Preferably, at least one of the plates is configured as a bipolar plate, and both sides of the bipolar plate surround at least one channel for the passage of a fluid, here a coolant, between them.

[0027] Unlike the cooling medium, deionized water that is decomposed into hydrogen and oxygen by electrolysis must be used as process water. Therefore, the process water is supplied separately from the cooling medium in the electrolyzer.

[0028] For any type of electrochemical cell, a frame can be integrally connected to the plate, and this frame is also produced using additive manufacturing. Thereby, the plate assembly comprises a plate and preferably further comprises a frame with the plate, and the frame is formed with a lattice structure and at least one reinforcing part. The lattice structure reduces residual stress in 3D printing, thereby functioning to produce printability. Further, the lattice structure functions to reduce the weight of the plate assembly and to resist the internal pressure in the electrochemically active region of an electrochemical cell such as a pressure vessel.

[0029] Openings for the operating medium and the coolant, as well as openings for the assembly of the cell stack, can also be located within this frame. The frame preferably has reinforcing parts around its periphery and around the plurality of openings. Such reinforcing parts are a large mass of fluid-tight accumulations of material made of the same material as the lattice structure is formed of. The reinforcing parts in the region of the openings function to carry the cooling medium and the operating medium and to withstand pressure. The reinforcing parts in the region of the periphery of the plate assembly function to provide a fluid-tight and pressure-resistant jacket around the plate assembly when the electrochemical cell is assembled.

[0030] Regardless of whether the external shape of the bipolar plate is purely flat or more complex, the reinforcing parts can be constructed from several different materials. In particular, the materials can be titanium on the anode side and stainless steel on the cathode side. Alternatively, the entire bipolar plate or even the entire additively manufactured components of the electrochemical cell can be constructed from the same material, such as a light metal, especially titanium. A preferred titanium alloy is Ti6Al4V, which is heat-treatable and forms a dense oxide layer. This increases the notch impact strength, which is an important factor in a pressurized system, and reduces the embrittlement of the material caused by hydrogen.

[0031] The porous transport layers in contact with the bipolar plate on both sides can be fabricated from the same material as the material on which the relevant surfaces of the bipolar plate are formed. This means, in particular, that by additive manufacturing, all layers of the porous transport layer on the anode side can be made from titanium, and all layers of the porous transport layer on the cathode side can be made from stainless steel. Alternatively, for example, the coarse porous inner layer of the porous transport layer in contact with the bipolar plate can be fabricated from copper. This particularly improves heat dissipation from the bipolar plate.

[0032] One advantage of integrated plate assemblies, aside from the efficient and process-reliable manufacturing method and the resulting low electrical resistance, is that a special type of additive manufacturing makes it possible to eliminate seals between individual half-cells in electrochemical cells, particularly electrolytic cells, redox flow cells, or fuel cells. In addition, the prefabrication of the finished, non-uniform sandwich-like plate assemblies facilitates a highly efficient, geometrically accurate, and process-reliable assembly of the entire cell stack.

[0033] The electrochemical cell, and in particular the electrochemical system such as an electrolytic cell according to the present invention, comprises at least one cell stack having two end plates, wherein at least one plate assembly and at least two polymer electrolyte membranes according to the present invention are arranged between the two end plates. Due to the small number of individual components, such a cell is highly impermeable to the working medium and coolant and can be constructed quickly and efficiently.

[0034] In particular, each end plate is integrally formed and comprises a plurality of additively manufactured, mutually parallel plates, the 3D printed layer is aligned perpendicular to the plate, and each end plate has an electrical contact assembly. Instead of bipolar plates provided to the plate assembly, each end plate is provided with a carrier plate having a porous multilayer transport layer on only one side. The carrier plate can also be configured to have cooling channels. Essentially, the end plate is constructed similarly to a plate assembly without a porous transport layer on one side. The end plate can also preferably be configured like a plate assembly with respect to a frame made of a grid structure, openings and reinforcements, thereby allowing it to be adapted to the shape and design of the plate assembly.

[0035] The general process for producing electrochemical systems can be outlined as follows:

[0036] In the first step, the plate assembly is produced using a 3D printing method, particularly a laser 3D printing method. The integrated plate assembly is preferably produced with a frame thickness in the range of 7 to 12 mm, particularly 9 mm. The thickness of the first inner layer of the porous transport layer is selected to be less than 0.5 mm in particular. The porous structure of the first inner layer of the porous transport layer is formed using a 3D printing method. The first inner layer has a filigree rod structure that forms an elongated honeycomb pattern. Due to the long overhang of this rod structure, the orientation of the plate, starting from the narrow edge of the plate, ensures technical productivity.

[0037] The thickness of the second outer layer of the porous transport layer is selected to be less than 0.2 mm. The microporous structure of the second outer layer of the porous transport layer is formed using a 3D printing method, and optionally by further subsequent processing such as laser drilling. The second outer layer of the porous transport layer is preferably created as a regular three-dimensional pyramidal structure on each of the first inner layers.

[0038] The reinforcing portion in the peripheral region of the frame or in the region of the channel for the working medium shall have a thickness of at least 0.5 mm in order to ensure that it is fluid-tight and pressure-resistant.

[0039] In the second step, the plate assembly is ground on both sides. The grinding process optionally includes grinding the surface of a second layer outside the porous transport layer.

[0040] Optionally, in the third step, laser drilling is performed to form further pores in the second layer outside the porous transport layer.

[0041] The fourth step involves subsequent cleaning of the plate assembly.

[0042] In a fifth optional step, one or both of the second layers outside the porous transport layer can be coated. For example, PVD (Physical Vapor Deposition) can be used. Catalytically active precious metals or precious metal alloys such as platinum and / or iridium have been found to be suitable coating materials.

[0043] In the sixth step, a seal is inserted into the grooves around the second layer outside the channel and porous transport layer for the working medium. This can be done by inserting an O-ring or by injection molding.

[0044] In the seventh step, a cell stack or electrochemical system is constructed, in which multiple electrochemical cells are stacked, clamped together between two clamp plates, and electrically isolated from each other.

[0045] Different exemplary embodiments of the present invention will be described in more detail below with reference to the drawings. [Brief explanation of the drawing]

[0046] [Figure 1] This shows the plate assembly of an electrochemical cell stack. [Figure 2] Figure 1 shows a cross-sectional view of a manufacturing plant for simultaneously producing multiple plate assemblies. [Figure 3] A plate assembly with a media distribution structure, schematically illustrated, is shown. [Figure 4] This shows a plate assembly with a frame. [Figure 5] Figure 4 shows a three-dimensional view of the plate assembly in partial cross-section. [Figure 6] Further three-dimensional representations of the plate assembly are shown in partial cross-sections with enlarged details. [Figure 7] Figure 6 shows a further enlarged view of the plate assembly on the anode side. [Figure 8] Figure 6 shows an enlarged view of the plate assembly on the cathode side. [Figure 9] Figure 6 shows a further enlarged view of the plate assembly on the anode side. [Figure 10] Figure 9 shows a further enlarged view of the plate assembly on the anode side. [Figure 11] Figure 6 shows a further enlarged view of the plate assembly on the anode side. [Figure 12] Figure 6 shows a further enlarged view of the plate assembly on the anode side. [Figure 13a] The steps in constructing an electrochemical cell are shown. [Figure 13b] The steps in constructing an electrochemical cell are shown. [Figure 13c] The steps in constructing an electrochemical cell are shown. [Figure 13d] The steps in constructing an electrochemical cell are shown. [Figure 13e] The steps in constructing an electrochemical cell are shown. [Figure 13f] The steps in constructing an electrochemical cell are shown. [Figure 13g] The steps in constructing an electrochemical cell are shown. [Figure 13h] The steps in constructing an electrochemical cell are shown. [Figure 13i] The steps in constructing an electrochemical cell are shown. [Figure 13k] The steps in constructing an electrochemical cell are shown. [Figure 14] A schematic diagram of the structure of an electrolytic cell comprising two electrochemical cells is shown. [Figure 15] This shows a schematic flow chart for the production of plate assemblies. [Modes for carrying out the invention]

[0047] The same reference numeral used in a drawing indicates the same component throughout.

[0048] Figure 1 shows a plate assembly 2 for stacking electrochemical cells 3 (see Figure 14). The plate assembly 2 is integrally formed and comprises several additively manufactured, parallel plates 4, 7, and 11, with the 3D printed layers aligned orthogonally to the plates 4, 7, and 11. Starting with a bipolar plate 4 having channels 15 for the cooling medium, porous transport layers 7 and 11 are provided on both sides. Each bipolar plate 4 has one side in contact with the anode-side porous transport layer 7 and the other side in contact with the cathode-side porous transport layer 11. Each porous transport layer 7 and 11 is constructed of two layers, as can be seen from Figures 1 to 3. The anode-side porous transport layer 7 at the rear of the electrochemical cell 3 has a first inner layer 8 of coarse porosity connected to the bipolar plate 4. On top of this is a more microporous second outer layer 8, which is connected to the first inner layer 8, and its surface 22' faces the anode side of the polymer electrolyte membranes 34, 34' in the subsequent electrochemical cell 3 (see Figure 14). The porous transport layer 11 on the cathode side of the subsequent electrochemical cell 3 has a coarsely porous first inner layer 12 connected to the bipolar plate 4. On top of this is a more microporous second outer layer 13, which is connected to the first inner layer 12, and its surface 22 faces the cathode side of the polymer electrolyte membranes 34, 34' in the subsequent electrochemical cell 3 (see Figure 14). Fine pores 14, 14' are found in the second outer layers 9, 13 of the porous transport layers 7, 11. In exemplary embodiments, the diameter of the pores 14, 14' is approximately 60 μm. The pores 14 and 14' are not necessarily arranged in the regular pattern seen in Figures 1 to 3. Rather, the pores 14 and 14' can be arranged and formed probabilistically. The two cathode-side layers 12 and 13 of the porous transport layer 11 are made of stainless steel. In this case, the two anode-side layers 8 and 9 of the porous transport layer 7 are made of titanium. The bipolar plate 4 is produced from titanium on the anode side and from stainless steel on the cathode side.

[0049] Figure 2 shows a cross-section of a manufacturing plant for simultaneously producing multiple plate assemblies 2 as shown in Figure 1 by additive manufacturing. The plates 4, 7, and 11, which are arranged parallel to each other, are produced additively on a plane that is aligned perpendicular to the plates 4, 7, and 11.

[0050] This is based on a 3D printing platform 21 on which multiple plate assemblies 2 are simultaneously constructed in the construction direction AR. For this purpose, a 3D printing device is used that can apply different materials to one identical layer and solidify them using a laser. These layers are generally referred to as 3D printed layers and are aligned parallel to the surface of the 3D printing platform 21, thereby aligning them perpendicular to the plate-like components 4, 7, and 11 of the plate assembly 2. Thus, each plate 4, 7, and 11 of the plate assembly 2 is constructed in the construction direction AR, starting from the narrow edge of the plate. In this way, the coarsely porous first layers 8, 12 of the porous transport layers 7, 11 can also be produced in high quality, which would be impossible if the plates 4, 7, and 11 were constructed horizontally, i.e., if one plate was constructed successively in the construction direction AR.

[0051] In the embodiment shown in Figure 2, five plate assemblies 2 are produced simultaneously. In particular, channels 15 for the cooling medium and channels 16, 17, and 18 for the working medium of the electrochemical system 10 are formed. In this case, the working medium is an oxygen-containing gas, a hydrogen-containing gas, and process water.

[0052] The configuration direction AR forms a right angle with the stacking direction ST of the plate assembly 2. After the plate assembly 2 is removed from the manufacturing plant indicated by 23 as a whole, only partially shown in Figure 2, the plate assembly 2 can undergo final mechanical processing.

[0053] The aforementioned channels 15, 16, 17, and 18 pass through the frame 19, which are also produced during the additive manufacturing process, as schematically shown in Figure 3. The porous transport layer 11 on the cathode side and the adjacent side of the bipolar plate 4 are allocated to the half-cell 5 of the subsequent electrochemical cell 3. The porous transport layer 7 on the anode side and the adjacent side of the bipolar plate 4 are allocated to the half-cell 6 of the subsequent electrochemical cell 3. The working medium is supplied through channels 15, 16, 17, and 18 in the frame 19 of each plate assembly 2, the coolant is supplied to the bipolar plate 4 through channel 15, and in the case of an electrolytic cell, channel 16 supplies process water, and channels 17 and 18 discharge the reaction products formed from the process water.

[0054] Figure 4 is a side plan view showing a plate assembly 2 having a frame 19, where the second outer layer 9 of the porous transport layer 7 is located above it. The frame 19 comprises a grid structure 20 and at least one reinforcing section 24. The grid structure 20 functions to reduce residual stress in 3D printing, thereby resulting in printability. Furthermore, the grid structure functions to reduce the weight of the plate assembly and to counteract the internal pressure of the electrochemically active region of the electrochemical cell 3, such as a pressure vessel. The reinforcing section 24 surrounds the periphery and multiple openings in the frame 19 in the form of channels 15, 16, 17, 18 and guide openings 26. Thus, the reinforcing section 24 forms a pressure barrier for the working medium and, in the region of the guide openings 26, forms a smooth guide for threaded bolts 33 used to clamp components of the electrochemical cell 3 (see Figures 13a to 13k). Furthermore, a sensor receiving space 25 is provided, which can be used in the electrochemical cell 3 to house a measurement assembly or wires for connecting such a measurement assembly. Channels 15, 16, 17, 18 and the porous transport layer 7 are each surrounded by grooves 27 that are created during 3D printing, which are intended to house an elastomer seal 30 (see Figure 5).

[0055] Figure 5 shows a partial cross-sectional view of the integrated plate assembly 2 according to Figure 4, illustrating its internal structure. Here, we can see the bipolar plate 4 having cooling channels 15 for the coolant, the first inner layer 12 and the second outer layer 13 of the porous transport layer 11 on the cathode side. Furthermore, we can see the first inner layer 8 and the second outer layer 9 of the porous transport layer 7 on the anode side, and the structure of the second outer layer 9.

[0056] Figure 6 shows a three-dimensional representation of a further plate assembly 2 in the plane of channel 15 within the bipolar plate 4 in a partial cross-section. In the enlarged detail shown on the right, a portion of the porous transport layer 7 on the anode side can be seen. Its first inner layer 8 (shown here but not actually visible) has a filigree rod structure that forms an elongated honeycomb pattern. The second outer layer 9 formed on top of it has a pyramidal structure.

[0057] Figure 7 shows a further enlarged view of the plate assembly 2 according to Figure 6 on the anode side, which has one piece of frame 19 and an outer second layer 9 of pyramidal structure on a first inner layer 8 (shown here but not actually visible) which has filigree rod structures forming an elongated honeycomb pattern.

[0058] Figure 8 shows an enlarged view of the cathode side of the plate assembly 2 according to Figure 6, which shows an enlarged view of the back of the plate assembly 2 having one piece of frame 19 and an outer layer 13 as shown in Figure 6. The outer layer 13 also has a pyramidal structure and is arranged on a first inner layer 12 (shown here, but not actually visible) which is in the form of a filigree rod structure that forms an elongated honeycomb pattern.

[0059] Figures 9 and 10 show an enlarged view of the plate assembly 2 on the anode side, according to Figure 6, along with a diagram of the first inner layer 8 in the actual diagram of the transparent honeycomb structure formed by 3D printing, i.e., without the second outer layer 9.

[0060] Figures 11 and 12 show a further enlarged view of the plate assembly 2 according to Figure 6 on the cathode side, along with a diagram of the first inner layer 12 in the actual diagram of the transparent honeycomb structure formed by 3D printing, i.e., without the second outer layer 13.

[0061] Figures 13a to 13k illustrate the steps for constructing two electrochemical cells 3 using the plate assembly 2 shown in Figures 4 and 5. Naturally, any number of electrochemical cells 3 can be installed here.

[0062] According to Figure 13a, a reinforcing plate 31 is provided and equipped with threaded bolts 33. The threaded bolts 33 are covered with an electrically insulating coating, which is made of plastic in particular. According to Figure 13b, an insulating plate 32, preferably made of non-conductive plastic, is pressed against the threaded bolts 33 and in contact with the reinforcing plate 31.

[0063] Here, according to Figure 13c, an end plate 28 follows, which is integrally formed and comprises additively manufactured parallel plates, and the 3D printed layer is aligned perpendicular to these plates. The plates of the end plate 28 consist of a carrier plate 4' and a porous (two-layer) transport layer 7. The end plate 28 also has electrical connection contacts 28'. The carrier plate 4' is made of stainless steel, and the porous transport layer 7 is made of titanium.

[0064] According to Figure 13d, the gas diffusion layer 36 is applied to or placed on the porous transport layer 7, which is formed from fluid-permeable, compressible carbon paper or carbon fleece. This is optional and serves to compensate for tolerances when the cell components are screwed together.

[0065] According to Figure 13e, a polymer electrolyte membrane 34 follows, and according to Figure 13f, a plate assembly 2 follows. According to Figure 13g, the anode side of the plate assembly 2, which is opposite the polymer electrolyte membrane 34, is covered with a gas diffusion layer 36' in the region of the second outer layer 9 of the porous transport layer 7, and according to Figure 13h, a further polymer electrolyte membrane 34' is applied.

[0066] To configure any number of electrochemical cells 3 in sequence, additional plate assemblies 2, gas diffusion layers 36, and polymer electrolyte membranes 34 can be optionally installed here.

[0067] As shown in Figure 13i, a further end plate 29 follows, which is integrally formed and comprises additively manufactured parallel plates, with the 3D printed layer aligned perpendicularly to these plates. The plates of the end plate 29 are composed in the form of a further carrier plate 4' and a porous transport layer 11, which is not visible here. The end plate 29 also has electrical connection contacts 29'. The carrier plate 4' and the porous transport layer 11 are made of stainless steel.

[0068] In this regard, it should be noted that the end plates 28 and 29 each correspond to, for example, half of the plate assembly 2, and a carrier plate 4' is provided in place of the bipolar plate 4, and that the channels 15 for the coolant can also be passed through this carrier plate 4'. The end plates 28 and 29 may also each have a frame 19 having a grid structure 20, openings for channels 15, 16, 17, 18 for fluid supply and discharge, guide openings 26, and reinforcing sections 24.

[0069] Here, as shown in Figure 13k, an additional insulating plate 32' and an additional reinforcing plate 31' are attached, and threaded nuts 35 are fastened to threaded bolts 33. The components of the formed cell stack 1 are held together by the threaded bolts 33 so that good mechanical contact and, if necessary, electrical contact are formed between the components. Fluid connections 37 for supplying and removing the working medium to the electrochemical cell 3 or reaction products from the electrochemical cell 3 are also attached to the ends of the support plates 31, 31'. Thus, the cell stack 1 here comprises two electrochemical cells 3 (see Figure 14).

[0070] Figure 14 shows an exploded view of an electrochemical system indicated in 10 of the configuration of an electrolytic system for producing hydrogen from water. The core component of the electrolytic system is a cell stack 1, i.e., a stack comprising at least two electrochemical cells 3, as shown in Figure 13k. A first electrochemical cell 3 comprising an end plate 29, a polymer electrolyte membrane 34', a gas diffusion layer 36', and a plate assembly 2 (anode-side half-cell 6) is shown in order, and a second electrochemical cell 3 comprising a plate assembly 2 (cathode-side half-cell 5), a polymer electrolyte membrane 34, a gas diffusion layer 36, and an end plate 28.

[0071] Referring to Figure 1, the frame 19 of the plate assembly 2 has a frame thickness d that corresponds to the total thickness of the plate comprising the bipolar plate 4 and porous transport layers 7, 11.

[0072] Figure 15 shows a schematic flow chart for the production of the electrochemical system 10. In the first step 40, the plate assembly 2 is produced in one piece using a 3D printing method. In the second step 41, the plate assembly 2 is ground on both sides. The grinding process optionally includes grinding the surface indicated by 22, 22' of the outer layers 9, 13 of the porous transport layers 7, 11. Optionally, in the third step 42, laser drilling follows to form further pores in the outer second layers 9, 13 of the porous transport layers 7, 11. The fourth step 43 includes subsequent cleaning of the plate assembly 2. In the fifth optional step 44, the outer second layers 9, 13 of the porous transport layers 7, 11 can be coated. For example, a PVD method with prior plasma etching of the surface to be coated can be used. Platinum has been found to be particularly effective as a coating material. In the sixth step 45, the seal 30 is inserted into the groove 27. In the seventh step 46, the cell stack 1 or electrochemical system 10 is constructed, and a stacking process is carried out, for example, as shown in Figures 13a to 13k. [Explanation of Symbols]

[0073] 1. Cell stack, electrochemical cell stack 2 Plate Assembly 3 Electrochemical cell 4 Bipolar plates 4' Carrier Plate 5 Half Cell 6 Half Cells 7. Porous transport layer, anode side 8. First inner layer of the anode-side porous transport layer 9. Second outer layer of the anode-side porous transport layer 10 Electrochemical systems, electrolytic systems 11 Porous transport layer, cathode side 12 First inner layer of the cathode-side porous transport layer 13 Second outer layer of the cathode-side porous transport layer 14, 14' opening, pore 15 Channels for the cooling medium 16 Channels for the operating medium 17 Channels for the operating medium 18 Channels for the operating medium 19, 19' frame 20 Lattice structure 21 3D Printing Platforms 22, 22' Surface of the outer layer of the porous transport layer 23 Manufacturing Plants 24 Reinforcement section 25 Sensor housing space 26 Guide opening 27 Groove 28 End Plates 28' Electrical connection contact 29 End Plate 29' Electrical connection contact 30 stickers 31, 31' Reinforcement Plate 32, 32' Insulating Plate 33 Threaded bolts (with electrical insulating coating) 34, 34' Polymer electrolyte membrane 35 Screw nuts 36, 36' Gas Diffusion Coating 37 Fluid connection section 40. Step 1: 3D Printing 41. Second step: Grinding process 42 Optional third step: Laser drilling 43. Step 4: Cleaning 44 Optional fifth step: Coating 45. Step 6: Installation of seal 30 46. ​​Step 7: Lamination AR configuration direction ST stacking direction d Frame thickness

Claims

1. A method for producing a plate assembly (2) for a stack (1) of electrochemical cells (3), wherein plates arranged parallel to each other are added to a plane oriented perpendicular to the plates.

2. The method according to claim 1, characterized in that a plurality of identical, mutually parallel plate assemblies (2) are constructed on a 3D printing platform (21), each comprising a plurality of different plates and standing perpendicular to the 3D printing platform (21).

3. The method according to claim 2, characterized in that different plates made of different materials are produced additionally on the 3D printing platform (21) and applied to the same 3D printing layer.

4. The method according to any one of claims 1 to 3, characterized in that at least one of the plates is produced as a porous multilayer (7, 11), and different layers (8, 9, 12, 13) of the porous layer (7, 11) differ from each other with respect to at least one of the parameters, which are layer thickness and porosity.

5. The method according to claim 4, characterized in that an opening (14) is introduced in at least one of the plates to create porosity.

6. The method according to any one of claims 1 to 5, characterized in that the plate assembly (2) is integrally formed from plates arranged parallel to each other.

7. A plate assembly (2) for an electrochemical system (10), comprising a plurality of integrally formed and additively manufactured parallel plates, wherein a 3D printed layer is aligned perpendicularly to the plates.

8. The plate assembly (2) according to claim 7, comprising the plate and a frame (19) having the plate, wherein the frame (19) is formed to include a lattice structure (20) and at least one reinforcing portion (24).

9. The plate assembly (2) according to claim 7 or 8, characterized in that at least one of the plates is configured as a bipolar plate (4), and both sides of the bipolar plate (4) surround at least one channel (15) for the passage of fluid between them.

10. The plate assembly (2) according to claim 9, characterized in that both sides of the bipolar plate (4) are made of different materials.

11. The plate assembly (2) according to claim 9 or 10, wherein each plate in contact with the bipolar plate (4) is configured as a porous multilayer transport layer (7, 11), and each individual layer (8, 9, 12, 13) of each transport layer (7, 11) differs from one another in terms of both layer thickness and porosity.

12. The plate assembly (2) according to claim 11, characterized in that the bipolar plate (4) is in contact with a porous transport layer (11) made of steel on one side and with a porous transport layer (7) made of titanium on the other side.

13. The plate assembly (2) according to any one of claims 8 to 12, characterized in that the frame (19) has a peripheral edge and a plurality of openings, and the reinforcing portion (24) is arranged on the peripheral edge and surrounds the openings.

14. An electrochemical cell (3), an electrochemical system in the form of an electrolytic cell, comprising a cell stack (1) having two end plates (28, 29), wherein at least one plate assembly (2) according to any one of claims 7 to 13 and at least two polymer electrolyte membranes (34, 34') are disposed between the two end plates (28, 29).

15. The electrochemical cell (3) according to claim 14, wherein each end plate (28, 29) is integrally formed and comprises a plurality of additively manufactured parallel plates, the 3D printed layer being aligned perpendicular to the plates, and each end plate (28, 29) has an electrical contact assembly (28', 29').

16. The electrochemical cell (3) according to claim 14 or 15, wherein each end plate (31, 31') comprises a carrier plate (4') having a porous multilayer transport layer (7, 11) on only one side.

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