CELL FRAME FOR AN ELECTROLYSIS CELL

Description

[0001] The invention relates to an electrolysis cell for generating gaseous hydrogen, which comprises at least one anion exchange membrane, at least one first cell frame, and at least one second cell frame arranged along a cell axis. The present invention is characterized by a particularly simple yet advantageous design of the electrolysis cell for the electrolysis process.

[0002] EP2898115B1 shows a cell frame for an electrolysis block, in particular for alkaline water electrolysis, with a front-side discharge channel structure and a rear-side discharge channel structure. The cell frame is formed from a material with sealing properties and has sealing beads and corresponding sealing notches on an opposite side. The cell frame further has product gas discharge structures for the separate discharge of two product gases through product gas discharge openings and discharge channels, wherein the product gas discharge openings are formed on the cell frame offset from one another by a predetermined angle in the circumferential direction, in particular by an angle between 5° and 60°.With regard to the simplicity of the design of the cell frames used and in particular with regard to the use of the cell frames in an electrolysis block for carrying out the electrolysis process, this disclosure shows only a partially satisfactory technical solution.

[0003] Furthermore, EP3696298A1 describes a cell frame for an electrolysis or fuel cell block with a plurality of collecting channel openings configured for media supply and media removal through the cell frame. The disclosed cell frame comprises a distribution channel structure configured for media supply from a respective supplying collecting channel opening to an associated half-space adjacent to the receiving opening and for media removal from this half-space to an associated, discharged collecting channel opening. This disclosed embodiment of a cell frame is only partially satisfactory in terms of simplicity of design and effectiveness of media supply and media removal.

[0004] The object of the present invention was to overcome the disadvantages of the prior art and to provide an electrolysis cell which is particularly easy to manufacture, while at the same time the physical process of electrolysis should be as efficient as possible.

[0005] This object is achieved by an electrolysis cell according to the claims.

[0006] The electrolysis cell according to the invention for generating gaseous hydrogen comprises, arranged along a cell axis, at least one anion exchange membrane, at least one first cell frame, and at least one second cell frame. The cell axis is preferably oriented horizontally. The cell frames each define an inner region provided for receiving an electrolyte and / or a membrane electrode assembly. The membrane electrode assembly is formed by the anion exchange membrane and at least one electrode and / or a diffusion layer. It is expedient if the membrane electrode assembly has a first electrode on a first flat side of the anion exchange membrane and a second electrode on a second flat side of the anion exchange membrane opposite the first flat side, one of the electrodes acting as the cathode in the electrolysis process and the other electrode acting as the anode.The diffusion layer ensures an electrically conductive connection between a flat side of a bipolar plate and an electrode arranged closest to the bipolar plate, whereby at the same time electrolyte can diffuse through the diffusion layer.

[0007] The at least one first cell frame and the at least one second cell frame are arranged such that they are spaced apart in the direction of the cell axis with respect to their respective spanned frame plane, wherein the first cell frame bears directly or indirectly on a first flat side of the anion exchange membrane in a liquid- and gas-tight manner, and the second cell frame bears directly or indirectly on an opposite second flat side of the anion exchange membrane in a liquid- and gas-tight manner. It should also be noted that an additional flat seal can be arranged along the cell axis between the first and / or second cell frame and the anion exchange membrane.

[0008] Furthermore, the electrolysis cell comprises at least one first flow channel and at least one second flow channel, each of which is formed by fluidically communicating openings in the first and second cell frames and in the anion exchange membrane, and whose main direction runs parallel or substantially parallel to the cell axis. The at least one first flow channel and the at least one second flow channel are spaced radially from the cell axis and positioned opposite one another with respect to the cell axis.

[0009] The at least one first cell frame and the at least one second cell frame each have at least one outflow channel structure, which is fluidically connected to the first flow channel and to the interior region of the respective cell frame. Furthermore, the at least one first cell frame and the at least one second cell frame each have at least one inflow channel structure, which is fluidically connected to the second flow channel and to the interior region of the respective cell frame.

[0010] The inflow channel structure and / or the outflow channel structure have at least two subchannels extending at an angle to one another, which subchannels open directly into the at least one first flow channel and / or exit directly from the at least one second flow channel. Each of the subchannels is fluidically connected to the interior of the respective cell frame.

[0011] The arrangement of the inflow channel structure and the outflow channel structure in conjunction with the sub-channels thus creates a favorable flow distribution in the interior of the electrolysis cell, which avoids the formation of regions with low flow velocities relative to the average flow velocity in the interior. This results in particularly advantageous flow through, in particular the most efficient possible flushing, of the interior region bounded by the cell frame and, subsequently, a high degree of removal of the product gases or gas bubbles formed in the interior regions of the cell frames. The described arrangement of the anion exchange membrane, the at least one first cell frame, and the at least one second cell frame creates an interior region bounded by the respective cell frame on each side of the anion exchange membrane.The respective inner area on each side of the anion exchange membrane thus forms a half-cell of the electrolysis cell, which half-cells are provided for carrying out the electrolysis.

[0012] During the electrolysis process, product gases are generated within the respective half-cell at the anion exchange membrane. The disclosed advantageous design of the electrolysis cell and the resulting advantageous flow conditions within the respective half-cell promote the detachment of gas bubbles from the anion exchange membrane in the edge regions of the respective half-cell. This not only increases the service life of the anion exchange membrane but also improves its effectiveness. A further advantageous effect is the even distribution of fluid or electrolyte within the half-cells due to the special design of the outflow channel structure and the inflow channel structure, and the associated improved cooling or, if necessary, improved warming of the anion exchange membrane, depending on the operating state of the electrolysis cell.

[0013] According to an advantageous development, it is possible for the first and / or second cell frame to have an inner boundary edge that defines a boundary section of the interior region, and for this inner boundary edge to have an upper and / or a lower rectilinear subsection in the upper region and / or in the lower region with respect to a vertically extending frame plane of the first and / or second cell frame. In this case, in the lower rectilinear subsection, at least one subchannel of the inflow channel structure runs parallel or aligned with the lower rectilinear subsection, and furthermore, in the upper rectilinear subsection, at least one subchannel of the outflow channel structure runs parallel or aligned with the upper rectilinear subsection.

[0014] It may be useful if the sub-channels of the outflow channel structure and / or the sub-channels of the inflow channel structure run in a straight line.

[0015] The main advantage of this development is that the operating medium flowing into and out of the interior of the electrolysis cell, or the electrolyte or a two-phase mixture of electrolyte and dissolved gases, is guided into the peripheral zones of the interior. This results in ideal utilization of the area of the anion exchange membrane that is active during the electrolysis process. It also results in a homogenized distribution of the operating medium in every interior area of a cell frame, or in every half-cell of the electrolysis cell, which further ensures a high efficiency of the electrolysis cell. This advantageous feature also improves the convective heat transfer between the operating medium and the respective cell frame, and subsequently between the active area of the anion exchange membrane and the respective cell frame.This advantageous effect increases the operational reliability of the electrolysis cell and also extends its service life. Furthermore, the requirements for material properties and thickness, or rather, the thickness extension along the cell axis of the anion exchange membrane, are reduced, which provides a significant economic advantage with regard to electrolysis cell production.

[0016] Also advantageous is a design according to which it can be provided that at least one sub-channel of the outflow channel structure is fluidically coupled to the inner region of the first and / or second cell frame with respect to the vertically running frame plane at an uppermost sub-section of the inner boundary edge. This measure achieves a particularly advantageous flow condition within the respective half-cell of the electrolysis cell since, on the one hand, no dome or cupola is formed in the upper region of the respective half-cell with respect to the vertical plane, in which dome an accumulation of gas bubbles would form during operation of the electrolysis cell. Such an accumulation of gas bubbles leads, among other things, to locally high resistances at the anion exchange membrane and thus to a possibly inadmissible thermal load.Secondly, this measure also prevents a depression from forming in the lower area of each half-cell relative to the vertical plane. Such a depression would lead to an area with low flow velocities, or to a dead space in the flow, and thus to a prevented exchange of operating medium. Such a prevented exchange would result in a thermally impermissible zone on the anion exchange membrane. In any case, this advantageous design of the electrolysis cell increases the efficiency of the electrolysis process within the electrolysis cell. Secondly, the service life of the anion exchange membrane is increased and safety is increased, as ideal flow through the respective half-cell of the electrolysis cell is ensured.

[0017] Furthermore, it can be provided that the at least one first cell frame and the at least one second cell frame are structurally and geometrically identical and are arranged rotated by 180° with respect to a vertical axis running in the vertical frame plane.

[0018] This advantageous development primarily results in the economic advantage of the common part principle. In addition to the production-related advantages, there are also advantages due to the reduced complexity in the assembly of an electrolysis cell. This reduces the probability of incorrect arrangement of the individual plate-shaped elements along the cell axis. Furthermore, the flow-guiding measures of the electrolysis cell for supplying the half-cells with operating medium are fully integrated into the respective cell frames. Since the thickness extensions of the cell frames make up the majority of the length extension of an electrolysis device consisting of several stacked electrolysis cells along the cell axis, this results in further economic advantages, particularly with regard to the cumulative manufacturing costs of such an electrolysis device.

[0019] Furthermore, it may be expedient if the at least one first cell frame and the at least one second cell frame each have an outflow channel structure and an inflow channel structure, and that the outflow channel structure and the inflow channel structure of the respective cell frame are formed by respective groove-like depressions or impressions in only one of the two flat sides of the respective cell frame.

[0020] The advantage here is that a flat side of a cell frame has no groove-like depressions or indentations for a channel structure, and thus a plate-shaped element adjoining this flat side along the cell axis, such as a flat gasket, has an increased service life. This results from the fact that each indentation or each opening in a cell frame causes a notch effect on the adjacent plate-shaped element due to a pressure-tight arrangement with the respective adjacent plate-shaped element. Especially when the electrolysis cell is operated with pulsating temperature and / or pressure loads, the plate-shaped elements experience relative sliding offsets or sliding movements with respect to one another, whereby an existing notch effect causes increased stress on the respective plate-shaped element.With the specified expansion of the electrolysis cell, such stress is now reduced by reducing or eliminating groove-like depressions or indentations on the flat side of a cell frame. This results in not only increased safety for the entire electrolysis cell, but also economic advantages with regard to the materials used for the cell frames and thus with regard to the time intervals between maintenance cycles.

[0021] Furthermore, it can be provided that the at least one first cell frame and the at least one second cell frame are arranged relative to the anion exchange membrane in such a way that the respective flat side of the cell frame is closest to the anion exchange membrane without groove-like depressions or impressions.

[0022] A particularly advantageous feature of this possible configuration is that the contacted clamping surface, or the contact area between the cell frames and a plate-shaped element closest to the flat side of the respective cell frame, in particular an anion exchange membrane or a flat gasket, is maximized. Thus, the seal between the at least one cell frame and the nearest plate-shaped element along the cell axis is particularly reliable, and furthermore, the stability of the electrolysis cell is increased by the homogenized and area-maximized contact between the plate-shaped elements.Furthermore, due to the minimized notch effect caused by the absence of groove-like depressions or indentations on a flat side of the respective cell frame, it is possible to arrange a plate-shaped element closest to the cell axis with a smaller thickness along the cell axis than in a design with groove-like depressions or indentations on the contacting flat side. This increases the efficiency of the electrolytic cell, as the ohmic resistance is reduced due to the smaller component thicknesses, or the thickness extension along the cell axis of the plate-shaped elements, and losses are reduced.

[0023] Furthermore, it may be expedient for the anion exchange membrane to be connected in a liquid- and gas-tight manner to the nearest flat side of the at least one first cell frame and / or the at least one second cell frame by gluing, welding, and / or pressing. Thus, the connection between at least one cell frame and the anion exchange membrane is essentially technically tight.

[0024] In addition to the effect of a gas-tight connection of the plate-shaped elements, this has the advantage that, on the one hand, the complexity of assembling the electrolysis cell is reduced, and thus potential sources of error due to incorrect assembly are reduced. On the other hand, this design eliminates the need for a sealing joint or sealing plane or an additional flat gasket between each cell frame and the anion exchange membrane, which overall improves the sealing of the electrolysis cell. Furthermore, the resulting improved stabilization of the anion exchange membrane is a beneficial effect that subsequently increases the service life of the electrolysis cell. Potential sources of error during the assembly of an electrolysis device composed of several electrolysis cells stacked along the cell axis are also reduced, since an assembly consisting of the cell frame and anion exchange membrane has already been formed.This simplifies the assembly of electrolysis cells arranged along the cell axis, as the number of individual components in the assembly process is reduced.

[0025] Also advantageous is a form according to which it can be provided that the inner boundary edge of the first and / or second cell frame has a circular arc shape or an elliptical shape in sections and, in the case of an elliptical shape, its main ellipse axis or its minor ellipse axis is oriented parallel or substantially parallel to the vertical axis.

[0026] This creates a directed flow around the edge areas of the interior of the cell frames, or the half-cells of the electrolysis cell. In combination with the disclosed positioning of the inflow channel structure and the outflow channel structure on the respective cell frame, an S-shaped flow pattern or flow turbulence is induced in the interior of the respective cell frames or in the half-cells of the electrolysis cell. The flow pattern within the respective half-cell is thus designed in such a way that the detachment of gas bubbles from the anion exchange membrane is favored. This, in turn, has a positive effect on the service life of the anion exchange membrane and on its service life and effectiveness. At the same time, the resulting rounded or rounded basic shape of the interior counteracts the possible formation of flow regions with low flow velocities.

[0027] According to the invention, the cross section of the at least one first flow channel and / or the at least one second flow channel of the electrolysis cell is designed to be increasingly tapered or increasingly enlarged along the cell axis.

[0028] This design creates the advantageous effect of a flow that is accelerated or decelerated as required in the flow channels of the electrolysis cell or in the flow channels of several electrolysis cells arranged along the cell axis. Depending on the situation of supplying an electrolysis cell with an operating medium via the flow channels and the desired optimal operating mode of the electrolysis cell, this measure positively influences the flow state of the flow from the inflow channel structure into the interior of the respective cell frame, i.e. into the respective half-cell. Furthermore, this measure has a beneficial effect on the flow state of the operating medium in the area of the first flow channel, in particular a two-phase flow consisting of operating medium and dissolved gases in the outflow channel structure.A technical advantage here is the effective removal of gas bubbles from the anion exchange membrane.

[0029] Furthermore, it can be provided that the at least one first flow channel is designed to be increasingly enlarged in a first flow channel direction along the cell axis and that the at least one second flow channel is designed to be increasingly tapered in a second flow channel direction opposite to the first flow channel direction.

[0030] This measure has a particularly advantageous effect on the flow state in the interior of a respective cell frame when several electrolysis cells are lined up or stacked at a distance along the cell axis, for example with at least one bipolar plate and any flat gaskets. Since the volume flow of an operating medium, which is supplied to the interior of the cell frame or to a half-cell via the at least one second flow channel, decreases in the at least one flow channel over its length along the second flow channel direction, the increasing tapering along the second flow channel direction keeps the flow velocity of the medium within a defined range, thus ensuring ideal supply to the respective interior areas of the electrolysis cells lined up or stacked along the cell axis.

[0031] Likewise, the at least one first flow channel, which widens along the first flow channel direction, ensures the continuous removal of the medium from the respective interior of the lined-up electrolysis cells. In addition to this effect, the at least one first flow channel, which widens along the first flow channel direction, has a positive effect on the transport of gas bubbles within the two-phase mixture to be removed from the interior of the respective half-cells of the electrolysis cells. The specified embodiment thus has a direct effect on an increased overall efficiency of electrolysis cells.At the same time, the continuous maintenance of the supply to each electrolysis cell improves the service life and safety of the same, since the volume flow of operating medium supplied and discharged as intended ensures sufficient cooling or, if necessary, the intended warming up and intensive gas bubble detachment from the anion exchange membrane in the respective electrolysis cell.

[0032] In particular, it may be advantageous if the flow cross-section of at least one partial channel of the outflow channel structure and / or the inflow channel structure has a widening starting from the respective flow channel in the direction of the inner region, which widening is designed in particular in a trumpet-shaped manner.

[0033] This further development is particularly advantageous because an accelerated flow is induced when flowing from the inner area into the respective sub-channel of the outflow channel structure, which promotes the entrainment of dissolved gas bubbles of a product gas in the two-phase mixture of fluid or operating medium and product gas from the respective half-cell, or from the inner area of the respective cell frame of the electrolysis cell.

[0034] Furthermore, it may be expedient for the at least two sub-channels of the outflow channel structure and / or the at least two sub-channels of the inflow channel structure to extend at an angle in the range between 27.5° and 135°, in particular at an angle of 90°, to one another and for at least one third sub-channel to be arranged between the at least two sub-channels of the outflow channel structure and / or for at least one third sub-channel to be arranged between the at least two sub-channels of the inflow channel structure.

[0035] This subsequently makes it possible for the cell frames to be designed with a thickness extension along the cell axis, i.e., with respect to the thickness of a cell frame, smaller than in an embodiment with two sub-channels per inflow and / or outflow channel structure, since the total channel cross-section of the respective sub-channels of the described further development is largely the same or similar in size to an embodiment with two sub-channels per inflow or outflow channel structure. Furthermore, the smaller thickness of the cell frames results in a reduced axial extension of the electrolysis cell and the significant advantage of lower thermal expansion of the cell frames under thermal stress, thus improving sealing and increasing the safety of the electrolysis cell.In addition, the described advantageous extension increases the power density per unit length along the cell axis of an electrolysis device consisting of several electrolysis cells.

[0036] According to a further development, it is possible for at least one elevation enclosing the outflow channel structure and / or the inflow channel structure and being closed all the way around to be formed along the inner boundary edge of the at least one first cell frame and / or the at least one second cell frame relative to the base area of the respective cell frame, said elevation being provided as a sealing element. In particular, it is advantageous if the at least one elevation or the sealing element is integrally connected to the respective cell frame, i.e., is designed as an integral component of the respective cell frame.

[0037] Since the sealing element is positioned as close as possible to the interior of the respective cell frame and encloses the inflow and outflow channel structure, this results in a particularly effective seal in the area between a cell frame and another plate-shaped element adjoining the flat side of the cell frame, such as a flat gasket or a bipolar plate. This effectively prevents the diffusion of product gases from the interior of a cell frame or from a respective half-cell.

[0038] Furthermore, it may be advantageous if the at least one circumferentially closed elevation is formed at least on one flat side of the at least one first cell frame and / or the at least one second cell frame and has a height of substantially 1% to 20%, preferably approximately 10% of the thickness extension in the direction of the cell axis of a plate-shaped flat seal arranged closest to this at least one flat side along the cell axis.

[0039] The advantage here is that a flat gasket located closest to the cell axis is specifically plastically deformed to increase or particularly effectively ensure the sealing effect between the cell frame and this plate-shaped element. Furthermore, operational sliding of, for example, a flat gasket relative to the adjacent cell frame is effectively prevented or significantly reduced by the circumferentially closed elevation.

[0040] In particular, it may be advantageous if the at least one first cell frame and / or the at least one second cell frame has isolated and / or connected surface sections with a higher surface roughness than the remaining surface on only one flat side or on both opposite flat sides.

[0041] This has the advantageous effect of reducing or even preventing operational sliding of the adjacent plate-shaped element in these surface areas, for example, due to thermal stress. Compared to a design without zones of increased surface roughness, this reduces or even prevents slippage of the individual components during the arrangement or assembly of the cell frames and the anion exchange membrane along the cell axis, thus avoiding sources of error.

[0042] According to a further development, it is possible for the partial channel intermediate regions between the partial channels to have a higher surface roughness than the remaining surface of the at least one first cell frame and / or the at least one second cell frame on the flat side with the groove-like depressions.

[0043] As described, this advantageous embodiment prevents mutual sliding between a plate-shaped element, in particular a flat gasket, located closest to the cell frame along the cell axis and the cell frame. This subsequently prevents a reduction in the cross-sectional area of the subchannels, which would occur due to sliding of the flat gasket.

[0044] Furthermore, it can be provided that the at least one first flow channel and / or the at least one second flow channel are formed by fluidically communicating elliptical openings at least in the first and second cell frames and in the anion exchange membrane.

[0045] This creates the positive effect that, with appropriate alignment, the elliptical flow channels exhibit a reduced or enlarged inner surface area of the flow channel in the vicinity of the outer and inner surfaces of the electrolysis cell, while at the same time, the appropriate dimensioning of the elliptical flow channel cross-section ensures a consistent flow rate. This ensures improved sealing of the elliptical flow channels along the cell axis of the electrolysis cell with respect to the interior or exterior of the electrolysis cell.

[0046] It may be expedient for the at least one first cell frame and / or the at least one second cell frame to be made of plastic. In particular, it may be expedient for the respective cell frame to be manufactured by injection molding. It may be provided that the openings for forming the flow channels are already provided in the injection-molded part, i.e., in the respective cell frame manufactured by injection molding.

[0047] The advantage here is that the unit costs for cell frames are lower due to the identical part principle in combination with the injection molding process as a manufacturing method compared to other manufacturing methods, such as machining blanks with the basic shape of a cell frame.

[0048] Furthermore, a method for producing at least one flow channel running along the cell axis by means of at least two electrolysis cells arranged along the cell axis according to one of the preceding claims is provided. In the present method, at least the electrolysis cells are arranged in a row along the cell axis and held relative to one another along the cell axis. Furthermore, the at least one flow channel is formed to taper or widen along the cell axis using a drilling device.

[0049] It is advantageous that the at least one flow channel is designed in such a way that the advantageous effects already described are achieved. When arranging or stacking the individual elements of the electrolysis cells, rotational offsets of the individual elements relative to one another around the cell axis can occur. These rotational offsets would result in a reduction in the size of the flow channels through the electrolysis device or the at least two electrolysis cells along the cell axis. By producing the at least one flow channel in the assembled or joined state of the at least two electrolysis cells, these reductions in the size of the at least one flow channel are reduced or completely avoided, thereby enabling effective operation in accordance with the design of the supply to the half-cells of the electrolysis cells.Furthermore, the channel structure of the flow channels through the electrolysis cells can be customized using this method with respect to the arrangement of the individual electrolysis cells along the cell axis. For example, it can be provided that different channel structures and / or channel cross-sections of the flow channels can be realized using the described method, depending on the required supply situation of an electrolysis cell and its positioning along the cell axis within an electrolysis device.

[0050] For a better understanding of the invention, it is explained in more detail with reference to the following figures.

[0051] They show in simplified, schematic and exemplary representation: Fig. 1 an exploded view of a possible embodiment of an electrolysis device; Fig. 2 the electrolysis device according to Fig. 1 in perspective view; Fig. 3 shows two electrolysis cells arranged along the cell axis; Fig. 4 shows a possible embodiment of a cell frame in a simplified and schematic view; Fig. 5 shows a possible embodiment of the cell frame in perspective view;

[0052] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or component designations, whereby the disclosures contained in the entire description can be applied mutatis mutandis to identical parts with identical reference symbols or component designations. Furthermore, the positional information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure, and in the event of a change in position, these positional information must be applied mutatis mutandis to the new position.

[0053] Furthermore, it should be noted that, in accordance with the list of reference symbols, terms from the list of reference symbols are used with and / or without a specific index in the description of the disclosure. Unless a precise differentiation of the terms with regard to their specific embodiment is necessary, no indexes are used. Conversely, for example, a subchannel 12a is differentiated from a subchannel 12b according to the respective description, with both still being subchannels 12.

[0054] In the Fig. 1 An exploded view of an embodiment of an electrolysis device 25 is shown. The electrolysis device 25 has at least two electrolysis cells 1a, 1b arranged stacked along the cell axis 6 or arranged in series according to Fig. 3 An electrolysis cell 1 can comprise at least one first cell frame 3 and at least one second cell frame 4, each arranged along the cell axis 6, as well as an anion exchange membrane 2. Furthermore, at least one flat gasket 23 and / or at least one bipolar plate can be arranged between two electrolysis cells 1 along the cell axis 6. Furthermore, the electrolysis cells 1a, 1b arranged along the cell axis 6 have flow channels formed by openings in the aforementioned flat or plate-like elements. In particular, the electrolysis cells 1a, 1b have at least one first flow channel 7 and at least one second flow channel 8. The flow channels 7, 8 run essentially parallel to the cell axis 6.

[0055] Fig.2 shows the electrolysis device 25 after Fig. 1 in assembled state. Furthermore, the frame plane 14 of the individual cell frames 4, 5, which runs vertically when the electrolysis device 25 is in use, is shown. The first cell frame 3 can be directly or indirectly in contact with a first flat side of the anion exchange membrane 2 in a liquid- and gas-tight manner, and the second cell frame 4 can be directly or indirectly in contact with an opposite second flat side of the anion exchange membrane 2 in a liquid- and gas-tight manner. The electrolysis device 25 can, as shown, comprise a plurality of electrolysis cells 1x.

[0056] In the Fig. 3 Two electrolysis cells 1 positioned along the cell axis 6 are shown in a highly simplified and schematic representation, whereby the same reference symbols or component designations are used for the same parts as in the previous Fig. 1 and Fig. 2 . The Fig. 3 shows in simplified schematic form a first electrolysis cell 1a and a second electrolysis cell 1b, which electrolysis cells 1 are arranged along the cell axis 6. Furthermore, the Fig. 3 Flat seals 23, which are arranged along the cell axis 6 before and after the electrolysis cell 1a and the electrolysis cell 1b. For a better understanding of the structure along the cell axis 6, the Fig. 2 an electrolysis device 25 in assembled state with several electrolysis cells 1x. As in Fig. 3 As shown, an electrolysis cell 1 comprises at least a first cell frame 3, an anion exchange membrane 2 and at least one second cell frame 4 stacked along the cell axis 6. According to the illustration, the first cell frame 3 and the second cell frame 4 are arranged at a distance from one another along the cell axis 6, the first cell frame 3 being arranged on a first flat side of the anion exchange membrane 2 and the second cell frame 4 being arranged on an opposite second flat side of the anion exchange membrane 2.

[0057] Through axially aligned or at least partially aligned openings in the electrolysis cells 1 and in the flat seals 23, as well as in any existing and in Fig. 2 At least one first flow channel 7 and one second flow channel 8 are formed by the bipolar plates 28 shown. The cell frames 3 and 4 each define an inner region 5, which is essentially formed as a central opening in these essentially plate-shaped or planar elements. The at least one first flow channel 7 and the at least one second flow channel 8 are spaced apart in the radial direction from the cell axis 6 and positioned opposite one another with respect to the cell axis 6.

[0058] Furthermore, at least one outflow channel structure 9 is provided, which is fluidically coupled to the first flow channel 7 and to the inner region 5. In addition, an inflow channel structure 10 is provided, which is fluidically coupled to the second flow channel 8 and to the inner region 5 of the respective cell frame 3, 4. The outflow channel structure 9 and / or the inflow channel structure 10 each comprise at least two sub-channels 12a, 12c, or 12d, 12f, which sub-channels 12 open directly into the first flow channel 7 and / or exit directly from the second flow channel 8, wherein each of the sub-channels 12 is fluidically coupled to the inner region 5. The inflow channel structure 10 and / or the outflow channel structure 9 can, as shown by way of example, be formed by distributing or fan-shaped sub-channels on or in the cell frames 3, 4.Accordingly, essentially triangularly defined mouth sections are created starting from the second flow channel 8 in the direction of the inner regions 5 of the cell frames 3, 4 and essentially triangular merging zones are created starting from the inner regions 5 of the cell frames 3, 4 in the direction of the first flow channel 7.

[0059] Furthermore, in Fig. 3 It is indicated schematically that the at least one first cell frame 3 and the at least one second cell frame 4 are structurally identical and can be arranged rotated by 180° around the vertical axis 16. A further possible embodiment can be that the at least one first cell frame 3 and the at least one second cell frame 4 are arranged relative to the anion exchange membrane 2 in such a way that the respective flat side of the cell frames 3 and 4 without partial channels 12 is arranged closest to the anion exchange membrane 2. It can be provided that the respective flat side of the cell frames 3 and 4, on which no partial channels 12 are formed, is dimensionally stable connected to the anion exchange membrane 2 by gluing, welding, and / or pressing. The connection of at least one cell frame 3 and 4 to the anion exchange membrane 2 is thus gas-tight and liquid-tight or essentially technically tight.The typically groove-shaped subchannels 12 are thus formed on or in the flat side of the first and second cell frames 3, 4 facing away from the anion exchange membrane 2. Thus, an assembly or an electrolysis cell 1 can be formed from at least one first cell frame 3, one second cell frame 4, and at least one anion exchange membrane 2. The respective inner region 5 of a cell frame 3 or 4 thus forms a half-cell on each side of the anion exchange membrane 2. The electrolysis process is carried out in an electrolysis cell 1, each including an anode half-cell and a cathode half-cell, which are fluidically separated by the anion exchange membrane 2.

[0060] In Fig. 3 It is schematically indicated that several electrolysis cells 1a or 1b can be arranged along the cell axis 6 and thus an electrolysis device 25 or a stack is formed, which electrolysis device 25 in Fig. 1 and Fig.2 is shown. For example, in such a series of electrolysis cells 1x, it can be provided that the cross section of at least one flow channel 7 or 8, which are formed by serially successive openings in the individual, essentially plate-shaped or flat components of the electrolysis cell 1, is designed to be increasingly tapered or increasingly enlarged along the cell axis 6. Thus, across the individual electrolysis cells 1x, an advantageous flow state of the operating media for the serially arranged electrolysis cells 1a or 1b can be created, as already described. Fig. 3 the possible arrangement of flat gaskets 23 between individual electrolysis cells 1 is shown. It can be provided that a flat gasket 23 is provided before and after each electrolysis cell. It can also be provided that bipolar plates 28 are provided between electrolysis cells 1 in order to ensure the voltage supply to the membrane electrode unit 27 and thus the electrolysis process. A membrane electrode unit 27 is assigned to the respective inner region 5 of a cell frame 3 or 4, i.e. the respective half-cells of an electrolysis cell 1, and is formed from at least one electrode and / or a diffusion or transport layer. The electrode and / or the associated diffusion layer is at least electrically conductively connected to the surface of the anion exchange membrane 2 delimiting the respective inner region 5 of the electrolysis cell 1.

[0061] In the Fig. 4 a further and possibly independent embodiment of the cell frame 3 or the cell frame 4 is shown in a simplified and schematic representation, wherein the same reference numerals or component designations are used for the same parts as in the previous Fig. 1-3 be used. The cell frame 3 or 4 can be designed such that the outflow channel structure 9 and / or the inflow channel structure 10 comprise at least two sub-channels 12a, 12c, or 12d, 12f, which run at an angle 11 to one another, which sub-channels 12 open directly into the first flow channel 7 and / or exit directly from the second flow channel 8. The sub-channels 12 are fluidically coupled to the inner region 5, i.e., are in flow communication with the inner region 5. The sub-channels 12 of the outflow channel structure 9 and the inflow channel structure 10 can be formed on a flat side of the respective cell frame 3 or 4 by respective groove-like depressions 17 or impressions in the cell frame 3 or 4. It is expedient if groove-like recesses 17 are formed in these flat sides, i.e. with rounded cross-sections, in which the operating media of the electrolysis cell 25 - Fig. 2 - can be directed.

[0062] Furthermore, it can be provided that a cell frame 3 or 4 each has an inner boundary edge 13, which inner boundary edge 13 in turn is arranged in a plane oriented towards a vertical plane 14 - Fig. 2 - related lower region and / or in an upper region, a lower and / or an upper rectilinear section 15a or 15b. In this case, it can be provided that in the lower rectilinear section 15b, at least one sub-channel 12f of the inflow channel structure 10 runs parallel or substantially parallel or aligned with the lower rectilinear section. Likewise, it can be provided that in the upper rectilinear section 15a, at least one sub-channel 12a of the outflow channel structure 9 runs parallel or substantially parallel or aligned with the upper rectilinear section 15a. In the embodiment shown, it can be seen that at least the sub-channel 12a of the outflow channel structure 9 is fluidically coupled to the inner region 5 of a cell frame 3 or 4, relative to the vertically extending frame plane 14, at an uppermost section of the inner boundary edge 13 with the inner region 5. As in Fig. 4 As shown, it is possible for the inner boundary edge 13 of a cell frame 3 or 4 to be circular or at least partially circular. Furthermore, an embodiment is possible in which the inner boundary edge 13 of a cell frame 3 or 4 is elliptical, with the major axis of the ellipse or the minor axis of the ellipse running parallel or substantially parallel to the vertical axis 16.

[0063] One possible embodiment of the cell frame 3 or 4 is that the sub-channels 12 are configured to expand in the direction from the respective flow channel 7 or 8 to the inner region 5 of the respective cell frame 3 or 4, in particular to be trumpet-shaped. This possible embodiment brings with it the advantages already described. It can also be provided that the at least two sub-channels 12a, 12c or 12d, 12f of the respective outflow channel structure 9 and / or inflow channel structure 10 extend at an angle 11 in the range between 27.5° and 135° to one another. In particular, the two sub-channels 12a, 12c or 12d, 12f can each be arranged at an angle 11 of 90°. At least one third sub-channel 12b or 12e can be arranged between the at least two sub-channels 12a, 12c or 12d, 12f of the respective outflow channel structure 9 and / or the inflow channel structure 10.

[0064] An expanded embodiment in which the sub-channels 12 of the outflow channel structure 9 and / or the inflow channel structure 10 each have different cross-sectional shapes and / or surface cross-sections can be particularly advantageous. For example, the sub-channel 12b can have a larger surface or flow cross-section than the sub-channel 12a in order to promote the removal of gas bubbles dissolved in the operating medium during operation of the electrolysis cell. At the same time, this effect is reinforced by a backflow effect of the two-phase mixture in the interior or inner region 5 of the respective cell frame 3 or 4, induced by the sub-channel 12a, which is smaller in relation to the surface cross-section, whereby the removal of the gas bubbles in the sub-channel 12b, which lies in the uppermost region of the inner region 5 with respect to the vertically extending frame plane 14, can be improved.

[0065] In the Fig. 5 1 shows a further and possibly independent embodiment of the cell frame 3 or the cell frame 4 in a perspective view, wherein the same reference numerals or component designations are used for the same parts as in the previous views. In this embodiment, it can be seen that at least one circumferentially closed elevation 21 is formed, which runs along the inner boundary edge 13 of the cell frame 3 or 4 and encloses the outflow channel structure 9 and / or the inflow channel structure 10. This at least one circumferentially closed elevation 21 can form a sealing element 22. This elevation 21 can be formed as a bead-like elevation integrally or in one piece with the respective cell frame 3 or4, wherein the elevation 21 has substantially 1% to 20%, preferably 10% of the thickness extension in the direction of the cell axis 6 of a nearest element arranged along the cell axis 6. As shown in the . Fig.1 bis Fig. 3 As shown, an element arranged closest to the cell axis 6 can be a flat gasket 23. Thus, the elevation 21 can preferably have a 10% projection relative to the base or main surface of the flat side of a cell frame 3 or 4, relative to the thickness extension of the flat gasket 23 along the cell axis 6.

[0066] One possible configuration of the embodiment shown is that a cell frame 3 or 4 has isolated and / or connected, surface-roughened zones on at least one flat side or on both opposite flat sides. The surface roughness of these zones can be increased compared to the surface roughness of the remaining flat side. These surface-roughened zones can be arranged individually. In particular, it can be expedient if the partial channel intermediate regions 24 have an increased surface roughness compared to the remaining surface of the same flat side of a cell frame 3 or 4. Likewise, the surface-roughened zones can be provided on the flat side of the cell frame 3 or 4 opposite the outflow channel structure 9 and inflow channel structure 10 in order to arrange orto facilitate the positioning and / or assembly of the anion exchange membrane 2 in conjunction with the cell frames 3, 4.

[0067] It can also be provided that the flow channels 7 and 8 are formed by elliptical openings 26, among others, in the elements of the electrolysis cell 1x - Fig. 2 - are formed. The elliptical openings 26 can be provided in all elements of the electrolysis cells 1x, such as in the cell frames 3 and 4, the anion exchange membranes 2, flat gaskets 23, and / or bipolar plates 28.

[0068] The embodiments show possible embodiments, whereby it should be noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments with one another are also possible and this possibility of variation lies within the skill of the person skilled in the art in this technical field due to the teaching of technical action by means of the objective invention.

[0069] The scope of protection is determined by the claims. However, the description and drawings must be used to interpret the claims. Individual features or combinations of features from the various embodiments shown and described may represent independent inventive solutions. The problem underlying the independent inventive solutions can be derived from the description.

[0070] All information on value ranges in this description is to be understood as including any and all sub-ranges thereof, e.g. the information 1 to 10 is to be understood as including all sub-ranges starting from the lower limit of 1 and the upper limit of 10, ie all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

[0071] For the sake of clarity, it should finally be pointed out that, in order to better understand the structure, some elements have been shown out of scale and / or enlarged and / or reduced in size. Bezugszeichenaufstellung

[0072] 1 Electrolysis cell 2 Anion exchange membrane 3 First cell frame 4 Second cell frame 5 Interior 6 Cell axis 7 First flow channel 8 Second flow channel 9 Outflow channel structure 10 Inflow channel structure 11 Angle 12 Partial channel 13 Inner boundary edge 14 Vertical frame plane 15 Straight section 16 Vertical axis 17 Groove-like depressions 18 First flow channel direction 19 Second flow channel direction 20 Widening 21 Elevation 22 Sealing element 23 Flat gasket 24 Partial channel intermediate area 25 Electrolysis device 26 Elliptical openings 27 Membrane electrode assembly 28 Bipolar plate

Claims

1. An electrolytic cell (1) for producing gaseous hydrogen, comprising - at least one anion exchange membrane (2), - at least one first cell frame (3) and at least one second cell frame (4), wherein each delimits an inner region (5) which is provided for receiving an electrolyte and / or a membrane electrode unit (27), and which first and second cell frames (3, 4) are spaced apart from one another in the direction of a cell axis (6) with respect to their respective defined frame planes, wherein the first cell frame (3) abuts on a first flat side of the anion exchange membrane (2) directly or indirectly in a liquid- and gas-sealing manner and the second cell frame (4) abuts on an opposite second flat side of the anion exchange membrane (2) directly or indirectly in a liquid- and gas-sealing manner, - at least one first flow channel (7) and at least one second flow channel (8), which are each formed by fluidically communicating apertures in the first and second cell frame (3, 4) and in the anion exchange membrane (2) and whose main direction extends parallel or substantially parallel to the cell axis (6), - wherein the first and second cell frame (3, 4) each comprise ∘ at least one outflow channel structure (9), which is fluidically coupled to the first flow channel (7) and to the inner region (5) of the respective cell frame (3, 4), and ∘ at least one inflow channel structure (10), which is fluidically coupled to the second flow channel (8) and to the inner region (5) of the respective cell frame (3, 4), - wherein the at least one first flow channel (7) and the at least one second flow channel (8) are spaced apart in the radial direction with respect to the cell axis (6) and are positioned opposite one another with respect to the cell axis (6), - wherein the outflow channel structure (9) and / or the inflow channel structure (10) each comprises at least two partial channels (12a, 12c, 12d, 12f) extending at an angle (11) to one another, which partial channels (12a, 12c, 12d, 12f) open directly into the at least one first flow channel (7) and / or emerge directly from the at least one second flow channel (8), and - wherein each of the partial channels (12a, 12c, 12d, 12f) is fluidically connected to the inner region (5) of the respective cell frame (3, 4), characterized in that the cross-section of the at least one first flow channel (7) and / or of the at least one second flow channel (8) of the electrolytic cell (1) is configured to be increasingly tapering or increasingly enlarging along the cell axis (6).

2. The electrolytic cell (1) according to claim 1, characterized in that the first and / or second cell frame (3, 4) is provided with an inner limiting edge (13) which defines a limiting section of the inner region (5), and which inner limiting edge (13) has, in relation to a vertically extending frame plane (14) of the first and / or second cell frame (3, 4) an upper and / or a lower straight section (15a, 15b) in the upper region and / or in the lower region, wherein in the lower straight section (15b) at least one partial channel (12f) of the inflow channel structure (10) extends parallel to or in alignment with the lower straight section (15b) and wherein in the upper straight section (15a) at least one partial channel (12a) of the outflow channel structure (9) extends parallel to or in alignment with the upper straight section (15a).

3. The electrolytic cell (1) according to any of the preceding claims, characterized in that at least one partial channel (12a) of the outflow channel structure (9) is fluidically coupled to the inner region (5) of the first and / or second cell frame (3, 4) with respect to the vertically extending frame plane (14) at an uppermost section of the inner limiting edge (13) with the inner region (5).

4. The electrolytic cell (1) according to any of the preceding claims, characterized in that the at least one first cell frame (3) and the at least one second cell frame (4) are structurally and geometrically identical and are arranged turned through 180° with respect to a vertical axis (16) extending in the vertically extending frame plane (14).

5. The electrolytic cell (1) according to any of the preceding claims, characterized in that the at least one first cell frame (3) and the at least one second cell frame (4) each have an outflow channel structure (9) and an inflow channel structure (10), and in that the respective outflow channel structure (9) and the respective inflow channel structure (10) of the respective cell frame (3, 4) are formed by respective groove-like indentations (17) or embossings in only one of the two flat sides of the respective cell frame (3, 4).

6. The electrolytic cell (1) according to claim 5, characterized in that the at least one first cell frame (3) and the at least one second cell frame (4) are arranged opposite the anion exchange membrane (2) in such a way that the respective flat side of the cell frames (3, 4) without groove-like indentations (17) or embossings is associated closest to the anion-exchanger membrane (2).

7. The electrolytic cell (1) according to claim 6, characterized in that the anion exchange membrane (2) is connected in a liquid-tight and gas-tight manner to the nearest associated flat side of the at least one first cell frame (3) and / or the at least one second cell frame (4) by bonding, welding and / or pressing.

8. The electrolytic cell (1) according to any of the preceding claims, characterized in that the inner limiting edge (13) of the first and / or second cell frame (3, 4) has a circular arc shape or an elliptical shape in sections and, in the case of an elliptical shape, its main elliptical axis or its secondary elliptical axis is oriented parallel or essentially parallel to the vertical axis (16).

9. The electrolytic cell (1) according to any of the preceding claims, characterized in that the at least one first flow channel (7) is configured to be increasingly enlarging in a first flow channel direction (18) along the cell axis (6) and in that the at least one second flow channel (8) is configured to be increasingly tapering in a second flow channel direction (19) opposite to the first flow channel direction (18).

10. The electrolytic cell (1) according to any of the preceding claims, characterized in that the flow cross-section of at least one partial channel (12) of the outflow channel structure (9) and / or of the inflow channel structure (10) is provided with a widening (20) starting from the respective flow channel (7, 8) in the direction of the inner region (5), which widening (20) is configured in particular to be trumpet-shaped.

11. The electrolytic cell (1) according to any of the preceding claims, characterized in that the at least two partial channels (12a, 12b) of the outflow channel structure (9) and / or the at least two partial channels (12d, 12f) of the inflow channel structure (10) extend at an angle (11) in the range between 27.5° and 135°, in particular at an angle (11) of 90°, to one another and that at least a third partial channel (12b) is arranged between the at least two partial channels (12a, 12b) of the outflow channel structure (9) and / or at least a third partial channel (12e) is arranged between the at least two partial channels (12d, 12f) of the inflow channel structure (10).

12. The electrolytic cell (1) according to any of the preceding claims, characterized in that along the inner limiting edge (13) of the at least one first cell frame (3) and / or of the at least one second cell frame (4) at least one protuberance (21) enclosing the outflow channel structure (9) and / or the inflow channel structure (10) and circumferentially closed is formed opposite the base surface of the respective cell frame (3, 4), which at least one protuberance (21) is provided as a sealing element (22).

13. The electrolytic cell (1) according to claim 12, characterized in that the at least one circumferentially closed protuberance (21) is formed at least on one flat side of the at least one first cell frame (3) and / or of the at least one second cell frame (4) and has a height of essentially 1% to 20%, preferably approximately 10%, of the thickness extension in the direction of the cell axis (6) of a plate-shaped flat gasket (23) arranged closest to this at least one flat side along the cell axis (6).

14. The electrolytic cell (1) according to any of the preceding claims, characterized in that the at least one first cell frame (3) and / or the at least one second cell frame (4) has, on only one flat side or on both opposite flat sides, isolated and / or continuous surface sections with a higher surface roughness than the rest of the surface.

15. The electrolytic cell (1) according to any of the preceding claims, characterized in that partial channel intermediate regions (24) between the partial channels (12a, 12c, 12d, 12f) have a higher surface roughness than the remaining surface of the at least one first cell frame (3) and / or of the at least one second cell frame (4) on the flat side with the groove-like indentations (17).

16. The electrolytic cell (1) according to any of the preceding claims, characterized in that the at least one first flow channel (7) and / or the at least one second flow channel (8) are formed by fluidically communicating elliptical apertures at least in the first and second cell frames (3, 4) and in the anion exchange membrane (2).

17. The electrolytic cell (1) according to any of the preceding claims, characterized in that the at least one first cell frame (3) and / or the at least one second cell frame (4) are made of plastic and in particular may be produced in one piece or integrally by injection molding.

18. The electrolytic cell (1) according to claim 17, characterized in that the apertures for forming the at least one first flow channel (7) and / or the at least one second flow channel (8) and / or the partial channels (12) and / or the circumferentially closed protuberance (21) in the at least one first cell frame (3) and / or in the at least one second cell frame (4) are / may be produced in one piece or integrally.

19. A method for producing at least one flow channel (7, 8) extending along the cell axis (6) by at least two electrolytic cells (1a, 1b) arranged along the cell axis (6) according to any of the preceding claims, wherein, - at least the electrolysis cells (1a, 1b) are arranged in a row along the cell axis (6) and are held relative to one another along the cell axis (6) - and the at least one flow channel (7, 8) is configured to be tapering or enlarging along the cell axis (6) by means of a drilling device.