EP4334496A1

EP4334496A1 - Water electrolysis stack for generating hydrogen and oxygen from water

Info

Publication number: EP4334496A1
Application number: EP21726334.2A
Authority: EP
Inventors: Stefan Höller
Original assignee: Hoeller Electrolyzer GmbH
Current assignee: Hoeller Electrolyzer GmbH
Priority date: 2021-05-03
Filing date: 2021-05-03
Publication date: 2024-03-13
Also published as: JP2024516306A; AU2021444032A1; CA3215991A1; WO2022233386A1; CN117242208A; KR20240004580A

Abstract

The water electrolysis stack (0) is used to generate hydrogen and oxygen from water and has a number of PEM-type electrolysis cells (2) arranged to form a cell stack (1). A first channel for supplying water, a second channel for removing water and the product gas oxygen and a third channel for removing the product gas hydrogen pass through the cell stack (1). The electrolysis cells (2) have a catalytically coated proton exchange membrane which adjoins a bipolar plate via a sealing frame on the hydrogen side, the rear face of which bipolar plate in turn rests on the membrane of the adjacent cell on the oxygen side. The bipolar plate is designed as a sintered component and has a planar metal plate on which a metal frame is situated that accommodates a channel-forming element in a central recess, and thereabove a second metal frame having a central recess and a porous transport layer incorporated therein. The channels of the channel-forming element connect the first and the second channel of the cell stack.

Description

Title: Water electrolysis stack for generating hydrogen and oxygen from water

description

[01 ] The invention relates to a water electrolysis sfack for generating hydrogen and oxygen from water, which consists of a large number of PEM-type electrolysis cells arranged in a cell stack. [02] Such electrolysis facks are state-of-the-art and are increasingly being used to generate “green hydrogen” from regenerative electricity. Such stacks are usually mechanically clamped as cell stacks between two end plates and have channels penetrating them near the sides of the stack, which supply the PEM electrolysis cells with the reactant water and cooling water and for the removal of the product gas oxygen and the cooling water on the one hand, as well as the product gas hydrogen on the other hand serve. While the removal of hydrogen within the cell stack is relatively unproblematic, the water supply, with which water as a reactant is to be supplied to the electrolytic cell in sufficient quantities on the one hand and is to be supplied and removed as cooling water on the other hand, is technically more demanding.

[03] It is part of the prior art to provide porous transport layers in the electrolytic cells, which consist of titanium expanded metals, titanium felt or sintered titanium powder. In order to be able to feed process media to or from these transport layers, transport channels are required, which are to be provided on the back of the transport layers in order to ensure that the cells are adequately supplied with high power density. This includes the prior art, bipolar plates with to use embossed channels, through which the water penetrating through the side channels in the stack can be brought up to the PEM in sufficient quantity and can be removed from it again. Alternatively, these channels are formed by inserting expanded metal between the transport layer† and a planar bipolar plate. Both variants have disadvantages. If channels are imprinted in the bipolar plate, then these are open to the transport layer and must be bridged by it. In the case of electrolysers that are operated with low operating pressures, this is usually not a problem. With increasing operating pressure, however, a supporting component, eg a perforated plate, must be inserted so that the porous transport layer does not press into the channels†. Such sinking components increase the construction volume and the costs.

[04] In this respect, the variant in which expanded metals are inserted between the transport layer and the planar bipolar plate is more favorable. Due to the construction of the expanded metal, however, there are metal sections that lie transversely within the direction of flow and form an additional barrier to the flow. This is particularly problematic when the expanded metals are heavily compressed within the stack. Multi-layer construction is then often necessary, which increases the thickness of the individual electrolytic cell and thus of the cell stack† and also leads to increased manufacturing costs†.

[05] Against this background, the invention is based on the object of simplifying and improving a water electrolysis stack of the aforementioned type with regard to its construction, in particular in order to avoid the aforementioned problems.

[06] This object is achieved by a water electrolysis stack mi† the features specified in claim 1. Advantageous design Features of the invention are given in the subclaims, the following description and the drawing.

[07] The water electrolysis cell according to the invention for generating hydrogen and oxygen from water has a number of electrolysis cells of polymer-electrolytic membrane construction arranged in a cell stack. There is at least a first passage through the cell stack for the water supply to the electrolytic cells and at least a second passage through the cell stack for removing the excess water/cooling water and removing the oxygen. In addition, at least a third channel passing through the cell stack is provided for removing the hydrogen. The electrolytic cells have bipolar plates which are formed from at least one silicon component. This sinter component is built up with a flat metallic piaffe on which is arranged a first metallic frame which has in its central recess a channel-forming element which is incorporated into this metallic frame. A second metallic frame is arranged on the first metallic frame and has a porous transport layer incorporated in its central recess. The channel-forming element is arranged in such a way that it conductively connects the first and second channels of the channels penetrating the cell stack†.

[08] The basic structure of the water electrolysis stack typically has a first channel for the water supply, which passes through the cell stack, and a second channel, usually arranged opposite, which also passes through the cell stack and is intended for removing excess water/cooling water, and above which the oxygen formed during the electrochemical reaction is removed. The third channel passing through the cell stack can also be formed in pairs by two opposite channels arranged near the remaining sides of the water electrolysis stack, but also through a single channel or adjacent channels. This channel is used† to remove the hydrogen formed during the electrochemical reaction.

[09] The bipolar plates of the water electrolysis stack according to the invention are formed from at least one sintered component; the bipolar plates are advantageously formed from only one sintered component, which preferably consists of titanium or a titanium alloy. The structure of the bipolar plates is extremely material-saving and effective, and the overall height is comparatively low.

[10] The channel-forming element arranged in a metal frame between a flat metal plate and another frame with an integrated porous transport layer† is intended for the supply and disposal of the oxygen side of the electrolytic cell. The channel-forming element, which has a large number of channels† connecting the first and second channels in the stack, ensures highly effective reactant/cooling water supply to the membrane and cooling water removal and oxygen removal from the membrane†. Due to the fact that the channel-forming elements of the bipolar plates are integrated into frames†, these only have to absorb comparatively small compressive forces, even when the water electrolysis stack is operated at a high operating pressure of, for example, 80 bar. In particular, they are not subject to the Pressure Equipment Directive as pressure-bearing components, as is the case, for example, with a corrugated embossing of the bipolar plate as a whole. For this reason, small thicknesses of material can be used for the channel-forming elements†. This results in large free flow cross sections, which are particularly advantageous for the flow of water through the stack. Adequate hydrogen removal must also be ensured on the hydrogen side, but this is much simpler† because of the pressure that builds up there. such as gaseous hydrogen, which requires only small flow cross-sections†.

[11] The sintering structure of the present invention is constructed with a flat metallic piaffe, a first metallic frame disposed thereon having a channel-forming member incorporated therein, and a second metallic frame disposed on the first metallic frame having a porous transport layer incorporated therein. This structure is not to be understood as exhaustive, but rather represents the components that are at least present for this sintered component according to the invention. The individual components are typically all made of titanium, they are either solid or, for example, produced in MIM injection molding as green parts or brown parts† and assembled and then sintered between ceramic plates, for example, to form a one-piece sintered component and thus a bipolar plate. [12] The provided on the oxygen side of the bipolar plate channel-forming element can be formed according to the invention either by a shaped sheet, typically a corrugated sheet or by a porous transport layer, which is traversed by channels. Since the shaped sheet essentially has a flow-guiding function, large flow cross-sections can be realized in the channels. The cross section does not have to be sinusoidal, but rather square waves or rounded square waves can be formed, which are advantageous with regard to the flowability. The corrugated metal sheet of this channel-forming element is advantageously designed on the oxygen side in such a way that the corrugation spacing is less than 2 mm, preferably less than 1.5 mm and, in a particularly preferred embodiment, less than 1.0 mm. Comparatively narrow, tall channels can therefore be implemented, which is advantageous. [13] If the channel-forming element is in the form of a porous transport layer, this can either be designed in such a way that the channels are completely integrated into the transport layer or in such a way that the channels are open at least on one side. In the latter case, it is advantageous to form them in such a way that they are closed off by the flat metal plate. In this way, a large channel cross-section can be achieved with a comparatively thin transport layer. The channels can be formed by inserting appropriate rods during injection molding of the green part, which are dissolved †thermally or chemically, or by embossing them into the surface of the transport layer†.

[14] It is advantageous according to the invention to arrange the channels of the channel-forming element as straight as possible and parallel to one another in order to achieve the lowest possible flow resistance. However, it can be advantageous to arrange the ducts in a wavy line shape and advantageously staggered parallel to one another in such a way that a barrier-free passage is maintained, but that the structural support function of the component is increased. The channels are then designed in such a way that they have a preferably rectilinear free passage, but are designed in a wavy manner in the side wall in order to achieve this supporting effect.

[15] For the purposes of the invention, barrier-free means that there are no flow-swirling baffles in the channels, as is typically the case with obstacles that are arranged at an angle transversely or obliquely to the direction of flow. A wavy canal can therefore be barrier-free if it runs through the body in a sinusoidal or wavy manner, for example.

[16] In principle, the channel-forming element can be arranged and designed in the first metallic frame in such a way that it mi† its ends to the first or the second channel that penetrates the cell stack for the water supply or for the water discharge and the oxygen discharge†. When operating the stack at high pressures, however, it can be advantageous not to form this channel-forming element continuously between the vertical channels to support this, but to provide corresponding channels on both sides in the metallic frame, for example by embossing, which are preferably in curse† to the Channels of the channel-forming element are located and the se mi† the first or the second channel penetrating the stack conductively connect. Such a design has greater stability and allows the channel-forming element to be designed for a lower supporting load.

[17] In order to enable hydrogen removal from the hydrogen-carrying side of the electrolytic cell through the bipolar plate, it is advantageous according to a further development of the invention to provide the flat metallic plate with recesses or openings which open into channels in the first metallic Frames are formed, e.g. by embossing† and which flow into the third cell stack through the channel for hydrogen removal. These channels can be open on one side and, after sintering, are covered and closed by the second metallic frame arranged on top†. The recesses in the flat metallic plate are advantageously designed as rows of adjacent openings which ensure that the hydrogen product gas can pass through sufficiently.

[18] In order to ensure a suitable discharge to the recesses in the flat metallic plate of the sintered component on the hydrogen side of the electrolytic cell, it is advantageous to provide a frame on the side of the bipolar plate formed by the flat metallic plate, which fits tightly against this side † and the one central Recess having† in which another channel-forming element is arranged, the channels of which are conductively connected to the recesses in the flat metal plate. At the same time, this frame advantageously forms the sealing element† between the bipolar plate and the PEM; The seals are arranged circumferentially around the recesses which form the channels passing through the stack and circumferentially around the central recess which forms the active part of the electrolytic cell. [19] This further channel-forming element, which is arranged on the hydrogen side of the electrolytic cell, can advantageously be designed as a gas diffusion layer made up of ordered or unordered carbon fibers. Carbon fibers are preferably arranged here, which are connected to form a felt-like knitted fabric. [20] Alternatively, this channel-forming element by a

Corrugated sheet metal or expanded metal can be formed. On the hydrogen side, no barrier-free ducting is usually required, since the hydrogen is pressure-driven and seeks its specified path in the stack.

[21] A gas diffusion layer can also be used as a channel-forming element on the hydrogen side, which is optionally supported by one or more support plates having recesses. This support plate can be designed in one piece with the frame, into which the material of the frame, which is made of sheet metal, is embossed in the area of the central recess, so that the necessary space for the gas diffusion layer is formed.

[22] In order to ensure a quasi-homogeneous supply of water over the entire surface of the proton exchange membrane (PEM) on the oxygen side, it is advantageous to pre- See which covers the sintered part on one side, enough for the microporous layer to extend to the second frame†. Extending the microporous layer to this area is particularly advantageous as it will mask† any gaps between a channel forming element or gas diffusion layer within the frame and thus provide a fully uniform delivery of reactant across the face of the membrane†.

[23] Such a microporous layer is advantageous as a single component, e.g. as a foil or as a green part or brown part of a foil production†, placed on the other components, in particular the second frame and the component integrated into the recess, and sintered with the others Components connected to the sintered component. Alternatively, the microporous layer can also be applied to the component using screen printing or stencil printing and is then subsequently sintered with these.

[24] The bipolar plate lies† with its† through the second frame and the porous transport layer† integrated into it and the microporous layer applied to it, on the oxygen side of the proton exchange membrane. [25] Each electrolytic cell consists of a bipolar plate, a

sealing frame and a proton exchange membrane (PEM), which is catalytically coated†. The cells are stacked on top of each other so that one bipolar plate is part of two adjacent electrolytic cells. Clamped is this stack of electrolytic cells between two end plates that are mechanically clamped together.

[26] Advantageously, the thickness of the first metallic frame, which encloses the above-described channel-forming element in its central recess, is less than 1 mm, preferably less than 0.8 mm or particularly advantageously even smaller than 0.6 mm. This reduces the height of the stack and the maferial costs for production.

[27] Since the properties of the porous transport layer before sintering are not always guaranteed, particularly in the case of very thin layers, which is expedient when handling the components, the porous transport layer can, according to a further development of the invention be produced with the aid of a feedstock which is fibre-reinforced, preferably with plastic fibres, particularly preferably with polyethylene fibres. These fibers are removed in the process from the green part to the brown part, at the latest during sintering†.

[28] The channels provided in the channel-forming element of the sintered component can either extend to the corresponding channels penetrating the cell stack or, which is advantageous in terms of pressure resistance†, be connected by channels in the area between the central recess and the channels penetrating the cell stack. which are formed by corresponding channel-shaped recesses from the first frame. Such recesses can be produced inexpensively by simply punching†, but a certain overlap must be ensured so that a line connection to the channels penetrating the cell stack is achieved†.

[29] The invention is explained below with reference to an embodiment shown in the drawings. Show it:

1 shows a water electrolysis stack according to the invention in a greatly simplified perspective view, FIG. 2 shows the structure of an individual electrolysis cell of the stack according to FIG. FIG. 3 shows an exploded view of a first embodiment of the structure of a bipolar plate formed by a sintered component,

FIG. 4 shows a perspective partial section through the components according to FIG. 2 in assembled form, FIG. 5 shows a partial section view corresponding to the components according to FIG

figure 4,

FIG. 6 shows an alternative design in the representation according to FIG

5,

FIG. 6.1 the sliced skin according to FIG. 6 with an oblique cutting line,

FIG. 7 shows a further embodiment variant in the representation according to FIG. 5, and

FIG. 8 shows another embodiment variant in the representation according to FIG

5. [30] The basic structure of an electrolysis sfack is part of the

State of the art and is described in detail in WO 2019/228616, to which reference is made. The electrolysis stack 0, as shown in FIG. 1, consists of a number of electrolysis cells 2 arranged in a stack 1 above one another, which are clamped between two end plates 3 and electrically connected in series. The electrical connections 4 and 5 are brought out of the stack 0 at the side. The cells 2 are supplied via the cell stack 1 through channels 6, 7, 8, namely a first channel 6 for supplying the reactant water and as cooling water and a second channel 7 for Removal of the cooling water and the product gas oxygen. These first and second channels 6 , 7 are arranged opposite one another parallel to the longitudinal sides of the cell stack 1 . Furthermore, three third channels 8 penetrating the stack 1 are provided on a transverse side of the cell stack 1 and are used to remove the hydrogen product gas. In the illustrated embodiment of the stack 0, the cell stack 1 is clamped under the incorporation of insulating plates 3 between a lower end plate 9 and an upper end plate 10, which is clamped by means of ten bolts 11, each under the incorporation of plate spring assemblies 12. The ducts 6, 7, 8 lead out to duct connections in the upper end plate 10; in the figure, the duct connections 13 and 14 are provided for connecting the first and second ducts 6 and 7, whereas the duct connection 15 is connected to the third duct 8 is connected and is used to remove the product gas hydrogen.

[31 ] An electrolytic cell 2 has a catalytically coated proton exchange membrane 16 (PEM) - also referred to as a membrane electrode assembly (MEA) - on whose hydrogen side there is a sealing frame 17†, which seals the active part of the cell 2, i.e. the memb ran 16 against the laterally arranged channels 6, 7, 8 and the channels 6, 7, 8 themselves to the outside to seal†. This sealing frame 17, which rests against the PEM 16 on the hydrogen side, i.e. on the side on which the product gas hydrogen is separated, is also provided with seals 18 on the side facing away from the PEM 16 and is located there on a bipolar plate 19 which is designed as a sintered component made of titanium and whose structure will be described below. On the other side of the PEM 16, i.e. on the side on which oxygen is separated off as product gas and on which water is supplied as reactant and water flows past for cooling†, the other side of a next bipolar plate 19 is located, as is the case with such Stacks is common. The current is supplied via the electrical connections 4, 5 between the end plates 4, 9, 10. [32] In the structure of the bipolar plate 19 shown in Figures 2 and 3, this has a flat metallic plate 20 made of titanium, which is rectangular in shape and has recesses 21 in the corners for guide rods for mounting the stack 0 provided and on the long sides with recesses, which form the first and second channels 6 and 7 in the cell stack 1, and on the short side with three recesses, which form the third channel 8 in the cell stack 1, which is formed here from three sub-channels . Parallel to the recesses for the third channel 8, a recess 22 is provided opposite, which is provided for the supply of nitrogen, with which the stack 0 is flushed before it is taken out of service.

[33] The bipolar plate 19 is designed as a sintered component and is constructed from the titanium components shown in FIG. One side of this bipolar plate 19 is formed by a flat metal plate 20, the other side of which comes to rest on a first metal frame component 23, which has a central recess 24, and the rest of the channels 6, 7, 8 forming recesses aligned those in the first plate 20 as well as the recesses for the guide rods and the recess for the nitrogen channel. The central recess 24 is provided for the incorporation of a corrugated metal sheet 25 which is arranged in the recess 24 of the first metallic frame member 23 such that channels are formed which run between the first and second channels 6,7. However, the channels do not open directly into the first and the second channel 6, 7, but into intermediate channels 26, 27 which pass through the stack through indentations in the first metallic frame component 23 between the central recess 24 and the recesses for the first and the second Channels 6, 7 are formed.

[34] Furthermore, this first frame member 23 has channel-forming indentations 28 in the transverse direction, which differ substantially from the The narrow side of the central recess 24 extend into the recesses delimiting the third channel 8 . The hydrogen conducted through recesses 29 in the flat plate 20 is conducted via these recesses into the drift channel 8 for the removal of the hydrogen. The intermediate channels 26 and 27 as well as the channels formed by the channel-forming indentations 28 can be formed either by indentations in the first metallic frame components 23 or by recesses that are arranged in a comb shape and must be arranged such that on the one hand they form the necessary line connections, on the other hand, remain materially connected, which can be achieved† by appropriate overlaps in channels 6, 7.

[35] This first frame component 23 is adjoined by a second metallic frame component 30, which also has aligned channel recesses and recesses for the guide rods, as well as a central recess 31 in which a porous transport layer 32 ( PTL) ) formed from titanium fibers is incorporated†. This layer 32 is formed from a fiber reinforced feedstock. This permeable transport layer 32 and the edge of the recess 31 are overlaid by a microporous transport layer 33 (Micro Porous Layer (MPL)), which is also made of titanium. These components 20, 23, 25, 30, 32, 33, which later form the bipolar plate 19, are sintered one on top of the other, so that a one-piece component 19 made of titanium is created, which mi† one side, namely on the oxygen side on the PEM 16† and the other side of which is in contact with the subsequent PEM 16 via the sealing frame 17†. To protect the PEM 16, the bipolar plate 19 does not lie directly against the PEM 16, but is separated by a protective film 34, which also has a central recess 35 and corresponding channel-forming recesses and recesses for the guide rods and thus only outside of the active area of the electrolytic cell is effective. [36] This sealing frame 17 has where the active part of the cell is, i.e. aligned with the central recess 24 provided in the metal frame component 23, a support plate 36, which is formed by the material of the frame itself and which is closed or can be perforated ausgebildef to lead the hydrogen from the membrane 16 ERS. This support plate 36 does not lie directly against the PEM 16, but with the interposition of a gas diffusion layer 38 (Gas Diffusion Layer (GDL)), which is made of carbon fibers. Near the recesses for the third channel 8, this support plate has a longitudinal slot 37 which is aligned with the recesses 29 in the flat plate 20 of the bipolar plate component and via which the hydrogen is removed.

[37] In the embodiment shown in FIGS. 4 and 5, the corrugated sheet 25 has an approximately sinusoidal cross section and has a pronounced corrugation length compared to the corrugation height. However, as the sectional representation according to FIG. 6 makes clear†, this can also be designed completely differently†, where the wave length is only slightly larger than the wave height. This sinusoidal shape can deviate from a square wave and then result in particularly smooth cross-sections through which flow can take place.

[38] A corrugated sheet metal 44 (Figure 6, Fi gur 6.1) similar to the corrugated sheet metal 25 or an expanded metal 43 (Figure 4, Figure 5) can also be integrated into the sealing frame 17. to distribute the forces within the active part of the electrolytic cell 2 evenly.

[39] The corrosion requirements on the hydrogen side are lower than on the oxygen side, which is why the sealing sheet metal 17 and possibly also the expanded metal 43 or corrugated sheet metal 44 lying on this side not necessarily made of titanium, but alternatively made of stainless steel with an anti-corrosion coating.

[40] As far as the channel-forming element in the sintered component 19, which forms the bipolar plate, is concerned, this can also be formed by embossing corresponding channels in a porous transport layer 39 instead of a corrugated sheet, which the PTL 32 in the second Frame member 30 and the corrugated sheet metal 25 in the first frame member 23 replace†. This PTL 39 has channels 40 which are open towards the flat metallic plate 20 and which extend from one end of the PTL 39 to the other and are arranged parallel next to one another. These channels, which are only open at the ends in the sintering component 19 after sintering, are then closed off on this one side by the flat metallic plate 20 or the sintered material formed thereby.

[41] Figure 8 shows an embodiment variant in which channels 41 pass through the PTL 42 in a similar way as is the case with the PTL 39 in Figure 7, but in which the channels 41 lie completely within the PTL 42 and only at the ends are open.

In the variant embodiment illustrated in FIGS. 7 and 8, the central recess 24 in the first frame component 23 is provided continuously between the recesses for the first and two channels 6, 7 penetrating the stack. No corrugated sheet metal 25 is provided here as the channel-forming element, which is integrated into the recess 24 and is used for channel transport between the first and second channels 6, 7, but rather a channel-forming element in the form of a porous sheet with channels 40, 41 running through it Transportschich† 39 and 42. The channels are one-sided, namely open to the flat plate 20 and are closed by it. Comparatively large channel cross-sections can be formed by means of pliers, and these channels 40, 41, since they are in the porous transport layer 39, 42 are always permeable towards the transport layer, i.e. the channels 40, 41 have a certain guiding characteristic, but no fluid-tight channel wall, as is the case with the channel-forming corrugated sheet 25 of the first embodiment variant.

Reference List

0 electrolysis bag

1 cell stack

2 electrolytic cells 3 insulating panels

4 electrical connection

5 electrical connection

6 first channel for the supply of water

7 second channel for the removal of hydrogen and oxygen 8 third channel for the removal of hydrogen

9 lower end plate

10 top end plate

1 1 bolt

12 Disc spring packs 13 Duct connection for water supply

14 Duct connection for water drainage and oxygen drainage

15 duct connection for hydrogen removal

16 Proton exchange membrane, PEM, also referred to as Membrane Electrode Assembly (MEA) 17 Sealing frame

18 sprayed seals

19 Bipolar plate, Sinfer construction file

20 level metallic piaffe

21 Recesses for fitting fifes 22 Recess for nitrogen flushing 23 first metallic frame component

24 central recess in 23

25 corrugated iron

26 intermediate channels for water 27 intermediate channels for water and oxygen

28 channel-forming impressions

29 recesses in 20 for hydrogen

30 second metal frame assembly

31 central recess in 30 32 Porous Transport Layer, PTL, also referred to as Porous Transport Layer†

33 Microporous Transport Layer†, MPL, also known as Micro Porous Layer†

34 protective film 35 central recess in the protective film

36 support plate in the sealing frame

37 slot

38 Gas Diffusion Layer† (GDL)

39 PTL in Figure 7 40 channels in Figure 7

41 channels in Figure 8

42 PTL in Figure 8

43 expanded metal on the hydrogen side

44 corrugated iron on the hydrogen side

Claims

Expectations

1. Water electrolysis bag (0) for generating hydrogen and oxygen from water, with a number of electrolysis cells (2) of the PEM design arranged to form a cell stack (1), with at least a first cell stack (1) penetrating channel (6) for water supply, with at least one second channel (7) penetrating the cell stack (1) for oxygen and water removal and with at least one channel (8) penetrating the cell stack (1) for hydrogen removal, in which the electrolytic cells (2) have bipolar plates (19) which are formed from at least one sinter component (19) which is built up with a flat metal piaffe (20) with a first metal frame (23) arranged thereon a channel-forming element (25, 39, 42) incorporated therein and having a second metallic frame arranged on the first metallic frame (23).

(30) with a porous transport layer (32, 39, 42) incorporated therein, wherein the channels of the channel-forming element (25, 39, 42) connect the first and second channels (6, 7) of the channels (6 , 7, 8) cable connection f. 2. Wasserelekfrolysesfack according to claim 1, characterized in that the channel-forming element is formed by a corrugated sheet (25) GE.

3. Water electrolysis bag according to claim 2, characterized in that the shaft distance of the corrugated sheet (25) is less than 2 mm, preferably less than 1.5 mm and particularly preferably less than 1.0 mm. 4. Water electrolysis bag according to claim 1, characterized in that the channel-forming element is a porous transport layer (39, 42) through which channels (40, 41) pass.

5. Water electrolysis stack according to one of the preceding claims, characterized in that the channels of the channel-forming element (25, 40) are designed to be open on one side and are closed by the flat metallic piaffe (20).

6. Water electrolysis bag according to claim 4, characterized in that the channels (41) of the channel-forming element (42) are designed as closed channels within the porous transport layer (42).

7. Water electrolysis smoker according to one of the preceding claims, characterized in that the channels of the channel-forming element (25, 39, 42) run in a straight line and/or in a wavy line, preferably parallel to one another,

8. Water electrolysis filter according to one of the preceding claims, characterized in that the channels of the channel-forming element (25, 39, 42) are designed to be barrier-free.

9. Wasserelekfrolysesfack according to any one of the preceding claims che, characterized in that the flat metallic piaffe

(20) has recesses (29) which open into channels (28) which are formed in the first metallic frame (23) and which open into the third channel (8) penetrating the cell stack (1) for hydrogen removal. 10. Water electrolysis stack according to one of the preceding claims, characterized in that at the me- metallic plate (20) formed side of the bipolar plate (19) abuts a frame (17) which has a central recess in which another channel-forming element is arranged, the channels of which are connected to the recesses (29) in the flat metallic plate (20) are line-connected.

1 1. Water electrolysis stack according to claim 10, characterized in that the further channel-forming element is formed by a gas diffusion layer (38) which preferably consists of carbon fibers arranged like a felt. 12. Water electrolysis stack according to claim 10, characterized in that the further channel-forming element is formed by a corrugated sheet (44) or expanded metal (43).

13. Water electrolysis stack according to one of the preceding claims, characterized in that the further channel-forming element preferably lies against the hydrogen side of a catalytically coated proton exchange membrane (16) with the interposition of a support plate (36) having recesses and a gas diffusion layer (38).

14. Water electrolysis stack according to one of the preceding claims che, characterized in that the sintered component (19) at a

side is covered† by a microporous layer (33) which extends† to the second frame (30).

15. Water electrolysis stack according to one of the preceding claims, characterized in that the microporous layer (33) is produced as a single component, placed and sintered with the other components (20, 23, 25, 30, 32) to form the sintered component ( 19) is connected.

16. Water electrolysis bag according to one of the preceding claims, characterized in that the microporous layer (33) is applied by screen printing or stencil printing and is subsequently sintered. 17. Wasserelekfrolysesfack surface according to one of the preceding Ansprü, characterized in that the bipolar plate (19) with its through the second frame (30) and the po rous Transportschichf incorporated therein (32) and the applied thereto mikropo rous layer (33) on the Oxygen soap against a Profonenaususch membrane (16)†.

18. Water electrolysis stack according to one of the preceding claims, characterized in that the thickness of the first metallic frame (23) is less than 1 mm, preferably less than 0.8 mm and particularly preferably less than 0.6 mm. 19. Water electrolysis stack according to one of the preceding claims, characterized in that the porous transport layer (32,39,42) is produced with the aid of a feedstock which is fiber-reinforced, preferably with plastic fibers, particularly preferably with polyethylene fibers . 20. Water electrolysis stack according to one of the preceding claims, characterized in that channels are formed in the first metallic frame (23) by recesses/indentations (26, 27, 28) which provide a line connection to a channel passing through the cell stack (1). (6, 7, 8) form.