EP4702173A1

EP4702173A1 - Cell-layer, frame and bipolar-plate for an electrolysis cell stack

Info

Publication number: EP4702173A1
Application number: EP23722838.2A
Authority: EP
Inventors: Lucas Prinsen
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2023-04-24
Filing date: 2023-04-24
Publication date: 2026-03-04
Also published as: CN121013919A; WO2024223017A1

Abstract

The invention relates to a cell-layer (200) for an electrolysis cell stack (60) of an electrolyser aggregate (51), in particular a water-electrolyser aggregate (51), comprising a frame (250), particularly a cathode frame (250), in which a transport structure (210) of the electrolysis cell stack (60) is accommodated in its major central area, wherein the frame (250) comprises at least one circumferentially open chimney-throughhole (256) serving for an outflowing product-medium (56) of the electrolysis cell stack (60), wherein offside the product-medium chimney-throughhole (256), between an inner edge of the frame (250) and an outer edge of the transport structure (210) a fluid passage (257) is arranged, wherein the fluid passage (257) opens into at least one product-medium chimney-throughhole (256).

Description

Title

Cell-layer, frame and bipolar-plate for an electrolysis cell stack

The invention relates to a cell-layer and a frame for an electrolysis cell stack of an electrolyser aggregate, in particular a water-electrolyser aggregate. Furthermore, the invention relates to a bipolar-plate for an electrolysis cell stack of an electrolyser aggregate, in particular a water-electrolyser aggregate. Moreover, the invention relates to an electrolysis cell stack, an electrolyser aggregate and an electrolyser system.

State of the Art

For example, in a water-electrolyser of an electrolyser aggregate (stationary or mobile), e. g. of an electrolyser system e. g. of or as an electrolyser installation, an electrochemical conversion of water into hydrogen and oxygen takes place with the use of electrical energy accompanied by the generation of heat. The electrolyser aggregate comprises at least one membrane-device formed as a simple membrane, a membrane-electrode-assembly (MEA) or a bipolar-mem- brane (BPM). The membrane-device may comprise an anion exchange membrane (AEM) and/or a proton exchange membrane (PEM).

Typically, the electrolyser aggregate is formed with a plurality of membrane-devices arranged in a stack and bipolar-plates arranged therebetween, with two electrode-chambers, an anode-chamber and a cathode-chamber, formed between each two membrane-devices and an interposed bipolar-plate. This arrangement forms the so-called electrolysis cell stack (cell stack, stack) with a large number of single electrolysis-cells (single-cells). Object of the Invention

In electrolytic cell stacks, especially with monolayer bipolar-plates, the production of a product-medium is quite inhomogeneous across the active areas of the electrolytic cell stacks. - It is an object of the invention to provide an alternative or improved electrolysis cell stack of an electrolyser aggregate, in particular of a water- electrolyser aggregate.

Disclosure of the Invention

The problem of the invention is solved by means of a cell-layer for an electrolysis cell stack of an electrolyser aggregate, in particular a water-electrolyser aggregate; by means of a frame, particularly a cathode frame, for an electrolysis cell stack of an electrolyser aggregate, in particular a water-electrolyser aggregate; by means of a bipolar-plate for an electrolysis cell stack of an electrolyser aggregate, in particular a water-electrolyser aggregate; by means of an electrolysis cell stack for an electrolyser aggregate; and by means of a electrolyser aggregate or electrolyser system. - Advantageous further embodiments, additional features and/or advantages of the invention result from the dependent claims and the following description.

In the state of the art - cf. fig. 2 - of electrolysis cell stacks 60 it is known to apply monolayer bipolar-plates (100) (not shown in fig. 2, cf. fig. 9 which shows an inventive bipolar-plate 100) which are provided with elongated corrugations for example by press-forming, wherein these corrugations are established on both sides of the bipolar-plates (100). These corrugations are oriented such that linear anode fluid-channels (120) are provided between a supply-medium inlet-chimney 93 and a discharge-medium outlet-chimney 94 on an anode-side (79) of the bipolar-plate (100) (perpendicular to the arrows in fig. 2), to feed the electrolysis cell stack 60 with a supply-medium 53. Such a fluid-chimney 93, 94, (96) may have more than one chimney-throughhole (cf. fig. 6, 8 and 9 which also show embodiments of the invention).

Based on experimental investigations of electrolytic cell stacks 60, the following was discovered. Since a flow direction of a product-medium 56 (direction of the arrows in fig. 2), for example the produced hydrogen 56, to the product-medium outlet-chimney 96 having one or more fluid-throughholes, is perpendicular to the above mentioned anode fluid-channels 120, the product-medium 56 must flow via a transport structure 210 (PTL, GDL etc., cf. below) to the product-medium outletchimney 96 on the cathode-side (89) of a single-cell 61 (cf. fig. 1). Hereby the production of the product-medium 56 towards a middle of a single-cell 61 is increased, since a pressure drop of the product-medium 56 must occur between the middle of the single-cell 61 and the product-medium outlet-chimney 96 to effect a flow of the product-medium 56 through the transport structure 120.

The inventive cell-layer overcomes the problem of a too inhomogeneous production of the product-medium. The cell-layer comprises a frame, particularly a cathode frame, in which a transport structure of the electrolysis cell stack is accommodated in its major central area, wherein the frame comprises at least one circumferentially open chimney-throughhole serving for an outflowing productmedium of the electrolysis cell stack, wherein offside the product-medium chimney-throughhole, between an inner edge of the frame and an outer edge of the transport structure a fluid passage is arranged, wherein the fluid passage opens into at least one product-medium chimney-throughhole. - The frame may also be constructed as an anode and cathode frame. Furthermore, the frame may be designed and/or designated as a PTL-frame and/or gasket.

The invention enables the product-medium in an electrolytic cell stack to use the anode fluid-channels at the cathode sides of the bipolar-plates. This means that the product medium no longer has to pass through the transport structure in plane direction, but only has to pass the transport structure in a direction perpendicular thereto, i. e. the longitudinal direction of the electrolysis cell stack. So, the production of the product medium across the active areas of the electrolytic cell stacks may be homogenised.

The frame is preferably made of a rigid polymer and/or is especially designed to define a substantial cathode-chamber at its inner circumference. The transport structure may be formed as a PTL (porous transport layer), a GLD (gas diffusion layer), a carbon element, a sintered metal element, a fibre element, a flow field and/or a flow structure etc. The transport structure may be part of a membrane- device (cf. below), may be formed as a separate part or may be a part of a bipolar-plate. A (cathode- and/or anode-)electrode at an electrode-chamber may be provided, as its name implies, on the membrane-electrode-assembly and/or may be provided on a side of the transport structure facing the membrane.

A second frame, in particular an anode-frame (for example of the same singlecell) of the electrolysis cell stack also has at least one product-medium chimney- throughhole. This at least one product-medium chimney-throughhole is on the one hand coaxial with the product-medium chimney-throughhole of the first frame, in particular the cathode frame, and is on the other hand, in contrary to the fist frame, formed circumferentially closed.

The fluid passage may be further confinable or confined by the bipolar-plate and/or the membrane-device for or of the cell-layer. The bipolar-plate may be constructed especially integrally (monolayer bipolar-plate) or may be made of a cathode-plate and an anode-plate firmly connected to each other (single-piece formation, duallayer bipolar-plate). The membrane-device may be in the form of a simple membrane, a membrane-electrode-assembly (MEA) or a bipolar-mem- brane (BPM), wherein the membrane-device may comprise at least one transport structure. The cell-layer, i. e. the frame (incl. the transport structure), the bipolar- plate and/or the membrane-device can, for example, be essentially rectangular, square, elliptical or circular.

The fluid passage may open into the actual product-medium chimney-throughhole as an inner portion of a product-medium outlet-chimney of the electrolysis cell stack. And/or the fluid passage may open into the circumferentially open section of the product-medium chimney-throughhole for the product-medium. Further, the fluid passage may connect exactly or at least two product-medium chim- ney-throughholes of exactly or at least one side of the frame. Moreover, the fluid passage has a width (diameter) between the frame and the transport structure of about 0.5% to 2.5%, in particular of about 1%, of an extension of the frame or the transport structure in its width direction or in its longitudinal direction, and/or may extend essentially perpendicular to fluid channels, especially anode fluidchannels, of a directly adjacent bipolar-plate. A single fluid passage may extend along an entire length of the transport structure preferably connecting two product-medium chimney-throughholes in the peripheral areas of the frame outside the transport structure. At least one or both product-medium chimney-throughholes may open at one or two sides of a cornerarea of the transport structure inside the frame. And two such single fluid passages may be arranged between two inner edges of the frame and two outer edges of the transport structure, wherein the fluid passages are arranged opposite each other in the cell layer with respect to the transport structure.

The frame may comprise at least one, preferably exactly or at least two, centring projections protruding into a fluid passage, which serve to centre the transport structure in the frame. The centring projection may be designed in such a way that it determines a width (diameter) of the fluid passage between the frame and the transport structure. Further, the centring projection may have a through- recess for a passage of the product-medium through or over the centring projection. Further, the centring projection and/or the frame may have a through-recess for bypassing the centring projection. The through-recess may be designed as a notch, groove or a throughhole at/in the centring projection.

At least one product-medium chimney-throughhole may not extend substantially along an entire side of the transport structure. This applies especially to all product-medium chimney-throughholes. In his case four product-medium chimney- throughhole may be established in the frame. The product-medium chimney- throughholes may be only arranged at the corner-areas of the transport structure in the frame. Furthermore, the respective product-medium chimney-throughhole may open at one or two sides of its corner-area at the transport structure.

The frame preferably further comprises at least one circumferentially closed chimney-throughhole serving for an inflowing supply-medium and at least one circumferentially closed chimney-throughhole serving for an outflowing dischargemedium especially on opposite sides in the frame. The second frame of the electrolysis cell stack also has at least one supply-medium chimney-throughhole and at least one discharge-medium chimney-throughhole. These chimney- throughholes are coaxial with the respective chimney-throughholes of the first frame and may be circumferentially closed or circumferentially open. The at least one supply-medium chimney-throughhole and/or the at least one discharge-medium chimney-throughhole may be arranged in the frame outside the product-medium chimney-throughholes or angled with respect to the productmedium chimney-throughholes. In the second case at least one product-medium chimney-throughhole may be at least partially in line with at least one supply-medium chimney-throughhole and/or at least one discharge-medium chimney- throughhole. - In circumferential direction of the frame, all chimney-throughholes may be arranged on a simple, single closed circumferential line in the frame. The closed circumferential line may be approximately rectangular, square, elliptical or circular in shape, and the active area of the bipolar-plate may have a similar configuration.

The frame may comprise at least four assembly-throughholes for clamping the frame in the electrolysis cell stack. An assembly-throughhole may be accommodated between a product-medium chimney-throughhole and a supply-medium chimney-throughhole or a discharge-medium chimney-throughhole, preferably in a corner-area of the frame. This applies in particular to the said four assembly- throughholes.

At least one, two, three, four or more assembly-throughholes may be accommodated in the frame between two adjacent product-medium chimney-throughholes on one side of the frame. Moreover, a space between assembly-throughholes or the assembly-throughholes of one side of the frame may be free of any chimney- throughholes. - Some or all assembly-throughholes are preferably arranged symmetrically with respect to two mutually perpendicular axes (main axes) in the bi- polar-plate. This also applies to the supply-medium chimney-throughholes, the discharge-medium chimney-throughholes and/or the product-medium chimney- throughholes of the frame.

The cell-layer may further comprise a bipolar-plate. The bipolar-plate may be constructed as a monolayer bipolar-plate comprising anode fluid-channels which are functional for a supply-medium. Such a bipolar-plate may be produced for example by press forming, die cutting etc. The anode fluid-channels of the bipolar-plate may be functional for the product-medium at a cathode side of the bipo- lar-plate. Further, the bipolar-plate may be constructed as an inventive bipolar- plate (see the following).

The inventive frame comprises an inner major central area for accommodating a transport structure for the electrolysis cell stack, wherein the frame comprises at least one or more centring projections protruding into the inner major central area. - Such a centring projection is intended for mechanically contacting the transport structure in the electrolysis cell stack. The centring projection and/or the frame preferably has a through-recess for allowing fluid to bypass the centring projection. Furthermore, the frame and/or the centring projection may be formed as described above or below (omitting the transport structure from the cell-layer, of course).

The inventive bipolar-plate comprises chimney-throughholes for fluid-chimneys in the electrolysis cell stack, wherein at least one chimney-throughhole serves for an inflowing supply-medium, at least one chimney-throughhole serves for an outflowing discharge-medium and at least four chimney-throughholes serve for an outflowing product-medium, wherein said at least four product-medium chimney- throughholes are arranged at at least four corner-areas or at at least four sectors of an active area of the bipolar-plate.

The active area of the bipolar-plate may correspond more or less to the area of a transport structure in an electrode-chamber of the electrolysis cell stack. - Respectively two directly adjacent corner-areas of the bipolar-plate may be arranged mirror-symmetrical with respect to a main axis of the bipolar-plate (rectangular or square bipolar-plate). Or respectively two directly adjacent sectors may be arranged rotation-symmetrical with respect to a centre of the bipolar-plate, wherein an angle of rotation is less than or equal to about 90° (elliptical or circular bipolar- plate).

Respectively two of the at least four corner-areas or respectively two of the at least four sectors may lie opposite to each other with respect to a centre of the bipolar-plate. I. e. at least two times two corner-areas or at least two times two sectors are opposite to each other with respect to the centre (e. g. essentially the (geometric) centre of gravity) of the bipolar-plate. A product-medium chimney- throughhole may be arranged exactly or at least at one side, or at both sides of its related corner-area. This can of course relate to more than one product-medium chimney-throughhole, especially two, three, four or more product-medium chimney-throughholes.

In circumferential direction of the bipolar-plate, said chimney-throughholes are arranged on a simple, single closed circumferential line in the bipolar-plate. The closed circumferential line may be approximately rectangular, square, elliptical or circular in shape, and the active area of the bipolar-plate may have a similar configuration. Furthermore, all chimney-throughholes of the bipolar-plate may be arranged on the simple, single closed circumferential line in the bipolar-plate.

The bipolar-plate may comprise assembly-throughholes for clamping the electrolysis cell stack. The assembly-throughholes may be arranged away from the outer corner-areas at only two sides of the bipolar-plate. The two sides of the bipolar- plate may be the two shorter sides of the bipolar-plate. For a respective outercorner assembly-throughhole, a product-medium chimney-throughhole can be arranged between an outer corner of the bipolar-plate and said assembly- throughhole. Preferably the bipolar-plate comprises only three, four or more assembly-throughholes at one side. Moreover, some or all assembly-throughholes are preferably arranged symmetrically with respect to two mutually perpendicular axes (main axes) in the bipolar-plate.

All assembly-throughholes of one side of the bipolar-plate may be arranged between product-medium chimney-throughholes. Preferably, the assembly-through- holes may also be arranged on or nearby the single closed circumferential line of the bipolar-plate. Furthermore, a space between assembly-throughholes or the assembly-throughholes of one side of the bipolar-plate is free of any chimney- throughhole.

Brief Description of the Figures

The invention is explained in more detail below by means of examples of embodiments with reference to the attached schematic and not scaled drawing. In the context of the invention, a feature may be positive, i. e. present, or negative, i. e. absent. In this specification, a negative feature is not explicitly explained as a feature unless, in accordance with the invention, it is emphasised that it is absent.

I. e. the invention actually made, and not one constructed by the prior art, is to omit this feature. The absence of a feature (negative feature) in an example of an embodiment shows that the feature is optional, if applicable (skilled person). - The merely exemplary figures (fig.) of the drawing show: fig. 1 in a simplified block diagram an embodiment of an electrolyser aggregate with an electrolysis cell stack, for an electrolyser system, fig. 2 a top view of a frame and a transport structure of an electrolysis cell stack, according to the explained above state of the art, fig. 3 to 7 top views of five exemplary embodiments of inventive cell-layers at least comprising a frame and a transport structure, fig. 8 a three-sided broken away top view of a centring projection of the frame for centring the transport structure, and fig. 7 a top view of a bipolar-plate of an electrolysis cell stack, according to an exemplary embodiment of the invention.

Embodiments of the Invention

The invention (cf. also above) is explained in more detail for an electrolysis cell stack 60 of an water electrolyser aggregate 51 (cf. fig. 1). However, the invention is also applicable to a CC>2-electrolyser aggregate. - In the drawing, only those sections of the electrolyser system are shown which are necessary for an understanding of the invention. - Although the invention is described and illustrated in more detail by preferred embodiments, the invention is not limited by the disclosed embodiments. Other variations may be derived therefrom without departing from the scope of protection of the invention.

Fig. 1 shows an electrolyser aggregate 51 according to a general embodiment, having at least one, in particular a plurality of electrochemical single-cells 61 (single electrolysis-cell 61) bundled into an electrolysis cell stack 60 housed in a preferably fluid-tight stack housing 66. Each single-cell 61 comprises an electrodechamber 62 formed as an anode-chamber 62 and an electrode-chamber 63 formed as a cathode-chamber 63, which are spatially and electrically separated from each other by a membrane-device 65.

Between two directly adjacent membrane-devices 65, 65 including a respective anode-chamber 62 and a respective cathode-chamber 63, a bipolar-plate 100 is arranged. The bipolar-plate 100 serves, among other things, to supply/discharge media 531 54, 56 for the anode-chamber 62 of a first single-cell 61 directly adjacent thereto and the cathode-chamber 63 of a second single-cell 61 directly adjacent thereto and, in addition, realises an electrically conductive connection between these single-cells 61 , 61. - The cathode-chambers 63 and, if appropriate, their common inflow-area, and/or their respective electrodes form a cathode 89, and the anode-chambers 62 and, if appropriate, their common inflow-area, and/or their respective electrodes form an anode 79 of the electrolysis cell stack 60.

The membrane-device 65 may be formed as a simple membrane, a membrane- electrode-assembly (MEA) or a bipolar-membrane (BPM). The membrane-device 65, i. e. its membrane, may comprise an anion exchange membrane (AEM) and/or a proton exchange membrane (PEM). A membrane-electrode-assembly 65 may have the form of a catalyst coated AEM I PEM (CCM). And a bipolar- membrane may have an AEM and a PEM. Furthermore, the membrane-device 65 may have at least one transport structure 210 (cf. fig. 2-6), as a porous transport layer (PTL) 210, a gas diffusion layer (GLD) 210, a carbon element, a sintered metal element 210, a fibre element 210, a flow field 210 and/or a flow structure 210 etc., on at least one of its two large-surface sides.

Instead of being part of a membrane-device 65 a transport structure 210 may also be a part separate from the membrane-device 65. Furthermore, a transport structures 210 may be part of a bipolar-plate 100. The transport structures 210 of the membrane-devices 65, the transport structures 210 as individual parts and/or the transport structures 210 of the bipolar-plates 100, which are not explicitly shown in fig. 1 , are arranged in the anode-chambers 62 and the cathode-chambers 63 of the electrolysis cell stack 60.

Frames 250 (cf. figs. 2 to 7) are included between a membrane-device 65 and two bipolar-plates 100 that each encompass a respective (anode/cathode) trans- port structure 210. Depending on a construction of the electrolysis cell stack 60, these (anode/cathode) frames 250 can each be a single part made of relatively compliant material, in which case it provides fluid sealing of the anode-chambers 62 and the cathode-chambers 63 to the outside of the electrolysis cell stack 60 and is often referred as a ‘gasket’ 250. Or an anode and/or cathode frame 250 may be constituted by multiple layers such as a layer of relatively hard material, encompassing the transport structure 210 and a layer of relatively compliant material, providing the said fluid sealing to the outside of the electrolysis cell stack 60. In some stack constructions such compliant, sealing layer is, however, vulcanized on the bipolar-plate 100, rather than being part of the frame 250.

In addition to the electrolyser aggregate 51 the electrolyser system comprises peripheral system components, such as a control unit, which may be one of the electrolyser installation itself, etc. - For supplying the electrolysis cell stack 60 with water 53 as a supply-medium 53 (inflowing), the electrolyser aggregate 51 has a water supply 70. Water 53 may also be understood to mean an alkaline aqueous electrolyte 53. And for discharging the media 54, 56 of the electrolysis cell stack 60, the electrolyser aggregate 51 has a media discharge 80.

The water supply 70 comprises in particular a water reservoir 73 for the water 53 (inflowing), a supply-medium-path 71 (medium-path 71) and a water conveying- device 76 at/in the supply-medium-path 71. - The media discharge 80 has at least one discharge-medium-path 81 (medium-path 81) for (warmed cooling) water 54 (outflowing) or (warmed cooling) water with produced oxygen 54 (outflowing) back into the water reservoir 73, possibly with a gas separator for oxygen, and/or in another direction (shown dashed), e. g. into the environment 2.

A product-medium 56 (outflowing/discharging) of the electrolyser aggregate 51 , i. e. the produced hydrogen 56, is transported away through a product-medium- path 82 (medium-path 82) of the media discharge 80. Here, a water separator 83 with a valve 84 may be used in the product-medium-path 82 to separate water in the product-medium-path 82. The water separated in the water separator 83 can be conveyed back into the water reservoir 73 or in another direction, e. g. into the environment 2, if applicable by gravity. The product-medium 56 can be stored, for example, in a hydrogen storage tank 85, whereby the product-medium-path 82 can lead directly in the hydrogen storage tank 85. It is of course possible to transport the hydrogen 56 away in another way.

Depending on an embodiment of the electrolyser aggregate 51 , a media guidance in the electrolysis cell stack 60 can be configured differently. Here, it is possible to provide a tempering different from an electrochemical function of the electrolysis cell stack 60, in particular a water cooling, or to realise the tempering together with the electrochemical function of the electrolysis cell stack 60.

In particular in the case of membrane-devices 65 with AEMs, it is possible to establish a supply of water 53 exclusively on the anode-side, if appropriate (dotted arrow at the anode 79). Here, the water 53 can flow directly into the 'anode' 79. Furthermore, in the case of membrane-devices 65 with PEMs, it is possible to establish a supply of water 53 exclusively on the cathode-side, if appropriate (dotted arrow at the cathode 89). Here, the water 53 can flow directly into the cathode 89.

In the case of an alkaline AEM-electrolyser which is operated on the anode-side and/or cathode-side with alkaline solution, e. g. a KOH solution, only anions, i. e. usually OH- ions, pass through the membrane-devices 65 in the direction to the electrodes of the of the anode 79. And in the case of a PEM-electrolyser, the membrane-devices 65 should only allow cations, i. e. usually H⁺ ions, to pass to the electrodes of the cathode 89.

In a PEM-electrolyser, water 53 may be supplied to the anode-chambers 62 and a discharge-medium 54 comprising water and oxygen is removed from them. The cathode-chambers 63 preferably contain the majority of the hydrogen produced.

In particular, the cathode-chambers 63 have a higher pressure, e. g. in the range of about 25bar to about 30bar and even higher. This pressure is higher than a pressure which is present in the anode-chambers 62 and is in the order of magnitude of about 1 bar to about 5 bar. The electrode-chambers 62, 63 must be sealed against each other in the electrolysis cell stack 60.

In an electrolysis cell stack 60 of a water-electrolyser aggregate 51 (cf. drawing), a flow of water 53 as a supply-medium 53 (reactant) is fed into the anode-chambers 62 of its single-cells 61 via a supply-medium inlet-chimney 93 (fluid-chimney 93) in the electrolysis cell stack 60. The supply-medium 53 then passes through the anode-chambers 62 of the single-cells 61 via an anode transport structure and anode fluid channels 120 of a bipolar-plate 100 (cf. fig. 9), and exits the single-cells 61 via a discharge-medium outlet-chimney 94 (fluid-chimney 94) of the electrolysis cell stack 60. These fluid-chimneys 93, 94 are preferably provided on opposite sides of the electrolysis cell stack 60 (flow direction of the supply-medium 53 in fig. 2 perpendicular and in fig. 9 according to the arrows).

During operation of the water-electrolyser aggregate 51 , oxygen is generated as an electrolysis product across the so-called active areas (that more or less correspond to the surface areas of the anode transport structures, also cf. an active area 110 of a bipolar-plate 100 in fig. 9) of the single-cells 61. The oxygen is carried away from the anodes in the anode-chambers 62 by a fluid flow in the singlecells 61 to the discharge-medium outlet-chimney 94, wherein in the anode-chambers 62 a two-phase fluid flow with an increasing oxygen content along the single-cells 61 towards the discharge-medium outlet-chimney 94 appears.

A similar arrangement may be provided for the cathode-sides of the single-cells 61 (cf. fig. 2 to 7 and 9), however in this case fluid-throughholes on either sides of the electrolysis cell stack 60 are established as a product-medium outlet-chimney 96 for the generated product-medium 56 as an electrolysis product during operation. The product-medium outlet-chimney 96 may comprise at least or more than one fluid-throughhole in the electrolysis cell stack 60, for which the frame 250 comprises an equal number of product-medium chimney-throughholes 256. This also applies to the fluid-throughholes for the other chimneys 93, 94 in the electrolysis cell stack 60. Accordingly the frame 250 also comprises at least one chimney-through-hole 253 for an inflowing supply-medium 53 and at least one chimney-throughhole 254 for an outflowing discharge-medium 54 preferably on opposite sides in the frame 250.

That the product-medium 56 can flow to the product-medium outlet-chimney 96 with a comparatively low pressure difference and a comparatively low pressure drop compared to the state of the art, cf. the invention (fig. 3 to 8), a size, especially a width (width direction WD), of a cathode transport structure 210 is less than an inner size, especially an inner width, of a major central area of the cath- ode frame 250 for receiving the transport structure 210, such that an open space 257 or a fluid passage 257 is created therebetween on at least one side between the frame 250 and its transport structure 210.

Via such an open space 257 or a fluid passage 257 in a cell-layer 200 at least comprising the frame 250 and the transport structure 210, the product-medium 56 can flow relatively freely from a middle of a single-cell 61 to the at least one fluid- throughhole of a product-medium outlet-chimney 96 in the electrolysis cell stack 60 (cf. arrows in fig. 7). For the product-medium outlet-chimney 96 the frame 250 comprises at least one product-medium chimney-throughhole 256 for the outflowing product-medium 56. The cell layer 200 is of course a part of a single cell 61 of the electrolysis cell stack 60. - This is particularly useful if a length dimension in longitudinal direction LD of a single-cell 61 is large and in particular larger than its width dimension in width direction WD of the single-cell 61 .

I. e. the cell-layer 200 comprises at least one fluid passage 257 between an inner edge of the frame 250 and an outer edge of the transport structure 210, wherein the fluid passage 257 is in fluid-communication with at least one product-medium chimney-throughhole 256 in the frame 250, which in turn is in fluid-communication with the product-medium outlet-chimney 96 of the electrolysis cell stack 60. For this, at least one product-medium chimney-throughhole 256 is circumferentially open in the frame 250, wherein the fluid passage 257 opens into the at least one product-medium chimney-throughhole 256. - Such a fluid passage 257, cf. fig. 3 and the arrows, is preferably established on both sides in width direction WD between the frame 250 and the transport structure 210 accommodated in the frame 250.

Preferably the frame 250 is provided with one or more centring projections 270, cf. fig. 8, to centre the transport structure 210, as shown in fig. 4 to 7, in the frame 250. It is preferred that a centring projection 270 extend over a full height or thickness (direction of the electrolysis cell stack 60) of the frame 250 to support (rather than dent into) the transport structure 210. For this case a through-recess (notch, groove, throughhole) is preferably established in the centring projection 270 and/or in the frame 50 near or behind the centring projection 270, to allow the product-medium 56 to pass around/behind the centring projection 270. - A reversal, i. e. providing the centring projection 270 at the transport structure 210 is of course possible.

Further, since the product-medium 56 directed to the product-medium chimney- throughholes 256, will mainly flow through the fluid passages 257, the fluid- throughholes of a product-medium outlet-chimney 96 in the electrolysis cell stack 60, i. e. also the product-medium chimney-throughholes 256 in the frame 200, need not extend over a large or nearly a full width WD of the frame 200, i. e. the cell-layer 200 and the single-cell 61. Instead, the product-medium outlet-chimney 96, i. e. the product-medium chimney-throughholes 256 in the frame 200 can be provided only at the corner-areas 212 of the transport structure 210 in the frame 200; cf. fig. 5 to 7. This also applies to a bipolar-plate 100, a membrane-device 65 and an anode frame of the respective single-cell 61.

This not only increases the strength and rigidity of the frame 250 as well as that of other components, but also allows for a more compact design of the entire electrolysis cell stack 60 by placing bolts of clamping devices 67 (assembly- throughholes for clamping the electrolysis cell stack 60) between these cornerareas 212. The clamping devices 67 of the electrolysis cell stack 60 may be placed between directly adjacent product-medium outlet chimneys 96 in the electrolysis cell stack 60 and therefore between directly adjacent product-medium chimney-throughholes 256 in the frame 200.

The electrolysis cell stack 60 may comprise at least four clamping devices 67 for clamping the single-cells 61 together as an electrolysis cell stack 60. A clamping- throughhole may accommodated between a fluid-throughhole of a product-medium outlet-chimney 96 and a fluid-throughhole of a supply-medium inlet-chimney 93 or of a discharge-medium outlet-chimney 94, preferably in a corner-area of the electrolysis cell stack; cf. fig. 3 and 4. Further, at least one, two, three, four or more clamping-throughholes may be accommodated in the electrolysis cell stack 60 between two adjacent fluid-throughholes of a product-medium outlet-chimney 96 on one side of the electrolysis cell stack 60. Moreover a space between clamping-throughholes or the clamping-throughholes of one side of the electrolysis cell stack 60 is free of any chimney-throughholes of any fluid-chimney 93, 94, 96 in the electrolysis cell stack 60. In the electrolysis cell stack 60 the at least one chimney-throughhole for the sup- ply-medium inlet-chimney 93 and/or the at least one chimney-throughhole for the discharge-medium outlet-chimney 94 may be arranged radially outside the at least one chimney-throughhole for the product-medium outlet-chimney 96 (cf. fig. 5 and 6) or angled with respect to the product-medium outlet-chimney 96 (cf. fig. 3, 4 and 7). In the angled case, at least two chimney-throughholes for the pro- duct-medium outlet-chimney 96 may lie on opposite sides of the electrolysis cell stack 60, wherein at least two chimney-throughholes for the supply-medium inletchimney 93 and the discharge-medium outlet-chimney 94 may also lie on opposite sides of the electrolysis cell stack 60, wherein these second sides are perpendicular to the said first sides.

In circumferential direction CD of a respective component of the electrolysis cell stack 60, all chimney-throughholes 253, 254, 256 of a frame 250 and/or all chimney-throughholes 153, 154, 156 of a bipolar-plate 100 may be arranged on a simple, single closed circumferential line CL of this component. This may additionally apply to assembly-throughholes 260, 160 or all assembly-throughholes 260, 160 of the frame 250 and/or the bipolar-plate 100. This also applies to the whole electrolysis cell stack 60, i. e. another component such as an anode frame, a mem- brane-device 65 etc.

An inventive bipolar-plate 100 comprises chimney-throughholes 153, 154, 156 for fluid-chimneys 93, 94, 96, wherein at least four product-medium chimney- throughholes 156 are arranged at at least four corner-areas 112 (fig. 9) or at at least four sectors (not shown) of an active area 110 of the bipolar-plate 100. Such a product-medium chimney-throughhole 156 may be arranged exactly or at least at one side, or at both sides of its related corner-area 112 of the active area 110.

A comparison of fig. 9 (bipolar-plate 100) with fig. 7 (cell-layer 200) shows again the anode-side (79, fig. 9) and cathode-side (89, fig. 7) flow of a respective fluid through a single-cell 61 of the electrolysis cell stack 60. In particular, due to the (anode) fluid channels 120 in the (monolayer) bipolar-plate 100, the respective fluid can flow on both sides at the active area 110 of the bipolar-plate 100 along the fluid channels 120. I. e. the anode fluid channels 120 of the bipolar-plate 100 are functional at the cathode-side of the bipolar-plate 100. When a cathode-side fluid reaches a fluid passage 257, which is in direct fluid-communication with a product-medium chimney-throughhole 256, the fluid enters the fluid passage 257, effectively turns and flows straight towards its nearest product-medium chimney- throughhole 256. - Here, the fluid passage 257 may be continued within the frame 250, i. e. it no longer needs to be additionally formed by the transport structure 210. This is also applicable to the other embodiments.

Claims

Patent Claims

1 . Cell-layer (200) for an electrolysis cell stack (60) of an electrolyser aggregate (51), in particular a water-electrolyser aggregate (51), comprising a frame (250), particularly a cathode frame (250), in which a transport structure (210) of the electrolysis cell stack (60) is accommodated in its major central area, wherein the frame (250) comprises at least one circumferentially open chimney-throughhole (256) serving for an outflowing productmedium (56) of the electrolysis cell stack (60), characterised in that offside the product-medium chimney-throughhole (256), between an inner edge of the frame (250) and an outer edge of the transport structure (210) a fluid passage (257) is arranged, wherein the fluid passage (257) opens into at least one product-medium chimney-throughhole (256).

2. Cell-layer (200) according to the preceding claim, characterised in that the fluid passage (257):

• is further confinable or confined by a bipolar-plate (100) and/or a mem- brane-device (65) for or of the cell-layer (200)

• opens into the actual product-medium chimney-throughhole (256) as an inner portion of a product-medium outlet-chimney (96) of the electrolysis cell stack (60), and/or

• opens into the circumferentially open section of the product-medium chimney-throughhole (256) for the product-medium (56).

3. Cell-layer (200) according to one of the preceding claims, characterised in that the fluid passage (257):

• connects exactly or at least two product-medium chimney-throughholes (256) of exactly or at least one side of the frame (250),

• has a width between the frame (250) and the transport structure (210) of about 0.5% to 2.5%, in particular of about 1%, of an extension of the frame (250) or the transport structure (210) in its width direction (WD) or in its longitudinal direction (LD), and/or

• extends essentially perpendicular to fluid channels (120), especially anode fluid-channels (120), of a directly adjacent bipolar-plate (100).

4. Cell-layer (200) according to one of the preceding claims, characterised in that:

• a single fluid passage (257) extends along an entire length (LD) of the transport structure (210) preferably connecting two product-medium chimney-throughholes (256) in the peripheral areas of the frame (250) outside the transport structure (210),

• at least one or both product-medium chimney-throughholes (256) open at one or two sides of a corner-area (212) of the transport structure (210) inside the frame (250), and/or

• two such single fluid passages (257) are arranged between two inner edges of the frame (250) and two outer edges of the transport structure (210), wherein the fluid passages (257) are arranged opposite each other in the cell layer (200) with respect to the transport structure (210).

5. Cell-layer (200) according to one of the preceding claims, characterised in that:

• the frame (250) comprises at least one, preferably exactly or at least two, centring projections (270) protruding into a fluid passage (257), which serve to centre the transport structure (210) in the frame (250),

• the centring projection (270) is designed in such a way that it determines a width of the fluid passage (257) between the frame (250) and the transport structure (210), and/or

• the centring projection (270) and/or the frame (250) has a through- recess (272) for bypassing the centring projection (270).

6. Cell-layer (200) according to one of the preceding claims, characterised in that: at least one product-medium chimney-throughhole (256) does not extend substantially along an entire side of the transport structure (210), • the product-medium chimney-throughholes (256) are only arranged at the corner-areas (212) of the transport structure (210) in the frame (250), and/or

• the respective product-medium chimney-throughhole (256) opens at one or two sides of its corner-area (212) at the transport structure (210).

7. Cell-layer (200) according to one of the preceding claims, characterised in that:

• the frame (250) further comprises at least one circumferentially closed chimney-throughhole (253) serving for an inflowing supply-medium (53) and at least one circumferentially closed chimney-throughhole (254) serving for an outflowing discharge-medium (54) on opposite sides in the frame (250),

• the at least one supply-medium chimney-throughhole (253) and/or the at least one discharge-medium chimney-throughhole (254) is arranged in the frame (250) outside the product-medium chimney-throughholes (256) or angled with respect to the product-medium chimney- throughholes (256),

• in circumferential direction (CD) of the frame (250), all chimney- throughholes (253, 254, 256) are arranged on a simple, single closed circumferential line (CL) in the frame (250).

8. Cell-layer (200) according to one of the preceding claims, characterised in that the frame (250) comprises at least four assembly-throughholes (260) for clamping the frame (250) in the electrolysis cell stack (60), wherein:

• an assembly-throughhole (260) is accommodated between a productmedium chimney-throughhole (256) and a supply-medium chimney- throughhole (253) or a discharge-medium chimney-throughhole (254), preferably in a corner-area of the frame (250),

• at least one, two, three, four or more assembly-throughholes (260) are accommodated in the frame (250) between two adjacent productmedium chimney-throughholes (256) on one side of the frame (250), and/or a space between assembly-throughholes (260) or the assembly- throughholes (260) of one side of the frame (250) is free of any chimney- throughholes (253, 254, 256).

9. Cell-layer (200) according to one of the preceding claims, characterised in that the cell-layer (200) further comprises a bipolar-plate (100), wherein:

• the bipolar-plate (100) is constructed as a monolayer bipolar-plate (100) comprising anode fluid-channels (120) which are functional for a supplymedium (53),

• the anode fluid-channels (120) of the bipolar-plate (100) are functional for the product-medium (56) at a cathode side of the bipolar-plate (100), and/or

• the bipolar-plate (100) is constructed as a bipolar-plate (100) according to one of the following claims.

10. Frame (250), particularly cathode frame (250), for an electrolysis cell stack (60) of an electrolyser aggregate (51), in particular a water-electrolyser aggregate (51), comprising an inner major central area for accommodating a transport structure (210) for the electrolysis cell stack (60), characterised in that the frame (250) comprises at least one or more centring projections (270) protruding into the inner major central area.

11 . Bipolar-plate (100) for an electrolysis cell stack (60) of an electrolyser aggregate (51), in particular a water-electrolyser aggregate (51), wherein the bipolar-plate (100) comprises chimney-throughholes (153, 154, 156) for fluid-chimneys (93, 94, 96) in the electrolysis cell stack (60), wherein at least one chimney-throughhole (153) serves for an inflowing supply-medium (53), at least one chimney-throughhole (154) serves for an outflowing dis- charge-medium (54) and at least four chimney-throughholes (156) serve for an outflowing product-medium (56), characterised in that said at least four product-medium chimney-throughholes (156) are arranged at at least four corner-areas (112) or at at least four sectors of an active area (110) of the bipolar-plate (100).

12. Bipolar-plate (100) according to the preceding claim, characterised in that:

• respectively two of the at least four corner-areas or respectively two of the at least four sectors lie opposite to each other with respect to a centre of the bipolar-plate (100),

• a product-medium chimney-throughhole (156) is arranged exactly or at least at one side, or at both sides of its related corner-area (112), and/or

• in circumferential direction (CD) of the bipolar-plate (100), said chimney- throughholes (153, 154, 156) are arranged on a simple, single closed circumferential line (CL) in the bipolar-plate (100).

13. Electrolysis cell stack (60) for an electrolyser aggregate (51), comprising a plurality of membrane-devices (65) and a plurality of bipolar-plates (100), which alternate with one another in the electrolysis cell stack (60), characterised in that the electrolysis cell stack (60) further comprises a plurality of cell-layers (200) between its membrane-devices (65) and its bipolar-plates (100), wherein cell-layers (200) are formed according to one of the preceding claims, and/or bipolar-plates (100) are formed according to one of the preceding claims.

14. Electrolysis cell stack (60) according to the preceding claim, characterised in that the electrolysis cell stack (60) comprises at least four clamping devices (67) for clamping the single-cells (61) together in the electrolysis cell stack (60), wherein:

• a clamping-throughhole is accommodated between a fluid-throughhole of a product-medium outlet-chimney (96) and a fluid-throughhole of a supply-medium inlet-chimney (93) or of a discharge-medium outletchimney (94), preferably in a corner-area of the electrolysis cell stack (60),

• at least one, two, three, four or more clamping-throughholes are accommodated in the electrolysis cell stack (60) between two adjacent flu- id-throughholes of a product-medium outlet-chimney (96) on one side of the electrolysis cell stack (60), and/or

• a space between clamping-throughholes or the clamping-throughholes of one side of the electrolysis cell stack (60) is free of any chimney- throughholes of any fluid-chimney (93, 94, 96) of the electrolysis cell stack (60).

15. Electrolyser aggregate (51) or electrolyser system, comprising an electrolysis cell stack (60), a water supply (70) and a media discharge (80), wherein the water supply (70) and the media discharge (80) are fluid-mechanically connected to the electrolysis cell stack (60), characterised in that the electrolysis cell stack (60) is formed according to the preceding claim.