ELECTROCHEMICAL CELL ARRANGEMENT FOR AN ELECTROLYZER

CROSS REFERENCE TO RELATED APPLICATION

[0001]This application claims priority to German Utility Model Application No. 20 2024 106 606.5, entitled “ELECTROCHEMICAL CELL ARRANGEMENT FOR AN ELECTROLYZER”, filed Nov. 15, 2024. The entire contents of the above-identified application is hereby incorporated by reference for all purposes.

TECHNICAL FIELD

[0002]The present disclosure relates to an electrochemical cell arrangement for an electrolyzer. Also disclosed is a method of manufacturing an electrochemical cell arrangement.

BACKGROUND AND SUMMARY

[0003]Electrolyzers typically comprise a stack of electrochemical cell arrangements, each of which has a plurality of layers, including separator plates and a membrane. The stack of electrochemical cell arrangements may have two end plates that press the electrochemical cell arrangements together and provide stability to the assembled stack. Furthermore, the electrochemical cell arrangements may comprise gas diffusion layers (GDL) and/or porous transport layers (PTL) arranged between the separator plate and the membrane.

[0004]The separator plate can fulfill several functions: indirect electrical contacting of electrodes of the membrane/a membrane electrode assembly (MEA), separation of media such as water, oxygen or hydrogen and electrical connection of neighboring electrochemical cell arrangements. The separator plate is often also referred to as a bipolar plate.

[0005]The separator plate typically comprises several through-openings, sometimes also called ports. These serve as an inlet or outlet for passing a fluid through the separator plate. Furthermore, the separator plate typically comprises a flow field, and a distribution region for guiding the fluid between a respective through-opening and the flow field. The separator plate usually carries different media on its two surfaces, for example a mixture of water and oxygen on the one hand and hydrogen on the other. These media carried on the separator plate or in the media compartments of the electrolyzer usually have a high pressure difference between each other or between the media-carrying compartments as well as an overpressure compared to the atmosphere.

[0006]Separator plates in electrolyzers are usually single-layered. Two-layer separator plates exist, for example, in the form that the flow field is designed as an additional metallic layer, which is arranged on a metallic base plate to form the separator plate. The separator plates disclosed here are not limited to any of the variants described.

[0007]In addition to the aforementioned components in the form of the separator plates, MEA, GDL or PTL, other components can also be provided within a cell arrangement. Cell frames and/or cell seals can be arranged between adjacent separator plates in order to fluidically seal the cells or the media from one another.

[0008]It is also known to use so-called insulation layers, which are typically made of a plastic and serve to electrically insulate components and/or neighboring cell arrangements from each other. In some cases, these insulation layers can also provide a sealing effect and thus replace known cell frames.

[0009]However, it was found that with the existing systems, especially with the existing sealing solutions, the sealing of the system is not always sufficient.

[0010]There is therefore a need to improve the reliability of the sealing of electrolyzers. The present disclosure provides a solution to this problem.

[0011]The present disclosure relates to an electrochemical cell arrangement, as well as a method, as described herein.

[0012]According to the present disclosure, the, in particular insufficient, interaction of previous insulation layers and neighboring components of an electrolyzer was recognized as a cause of the sealing problems observed to date.

[0013]For example, it was found that conventional cell frames and insulation layers often have comparatively low rigidity. In addition, these are often inadequately or unfavorably supported at the edge of the flow field. As a result of pressing and/or pressurization of the cell stack, these components can be subjected to excessive local loads and be inadequately supported, at least in sections. As a result, they can become unfavorably deformed or damaged. This can also be transferred to other components, such as an adjacent membrane or seal, which no longer experience/receive sufficient structural support. As a result, these neighboring components can buckle or tear and/or a planar contact and thus a mutual planar support can be interrupted, at least locally. This can also result in leakage problems or general reliability problems.

[0014]Accordingly, an electrochemical cell arrangement with a separating layer with increased rigidity is proposed here, which can reliably fulfill its function, in particular with regard to supporting an adjacent membrane, even if the structural support is not continuous.

[0025]In the case of a single-layer separator plate, the fact that a cell arrangement comprises at least part of a separator plate can be understood to mean that at least one of the first and second sides of the separator plate is to be assigned to a given cell arrangement. The corresponding other side can be assigned to a corresponding neighboring cell arrangement. In the case of a two-layer separator plate, a corresponding single layer of the separator plate, which has one of the first and second sides of the two-layer separator plate, can be regarded as a part of the separator plate in a given cell arrangement. The corresponding other layer, which has the corresponding other side of the two-layer separator plate, can be assigned to a neighboring cell arrangement.

[0026]The flow field can be part of an electrochemically active region of the cell arrangements and/or form an electrochemically active region of a respective separator plate. For example, the electrochemically active region of a respective separator plate and thus its flow field can be delimited by an orthogonal projection of the membrane, in particular of its actual membrane surface and, for example, not of any reinforcing edges, onto the sides of the separator plates that face the inside of the cell. Accordingly, the flow field lies in this region of a separator plate delimited by the orthogonal projection. It is optionally set up to guide reaction fluids through this region by means of a channel structure of the flow field.

[0027]The distribution regions can be used to connect the flow field to at least one of the through-openings in a fluid-conducting manner. The channels and webs of the distribution regions can merge into channels and webs of the flow field and/or branch out towards them and/or transfer fluid to them or receive fluid from them.

[0028]The through-openings can be aligned with through-openings of neighboring cell arrangements in a manner known per se in order to form fluid channels for guiding reaction media in a stack of several cell arrangements. Accordingly, the through-openings can serve as inlets or outlets for passing a fluid through the separator plate. The through-openings can also be referred to as ports.

[0029]Optionally, the membrane may be comprised in or form a membrane electrode unit of known design. For example, it can be designed as a proton exchange membrane, PEM.

[0030]The separating layers can be flat and/or layered components. They can have a constant thickness, at least in the non-installed and/or non-loaded state, with the exception of any ridges explained below. In contrast to homogeneous plastic insulation layers of the prior art, however, the separating layers disclosed herein may, in accordance with the following embodiments, in particular have a multi-part structure and/or comprise inhomogeneous materials.

[0031]Furthermore, in deviation from the state of the art, according to embodiments, it is provided that an electrically insulating function is combined with increased structural rigidity in a single separating layer. A structurally rigid layer, as encompassed by at least one separating layer, can be understood to mean that it is dimensionally stable under its own weight and/or under mechanical clamping pressures and/or under electrochemical operating pressures. In particular, the structurally rigid layer can at most be deformed elastically and not plastically in such situations. The separating layer with the increased structural rigidity is optionally positioned on the side of the electrochemical cell that has to absorb the higher pressure of the opposite side of the electrochemical cell.

[0032]According to one variant, the structural rigidity of the separating layers comprises that they have a modulus of elasticity of more than 60,000 Mpa (megapascals).

[0033]The frame-like shape of the separating layers can comprise the fact that they each have a recess and run around this recess. In particular, a respective separating layer can have, for example, a central recess with a closed circumference and can delimit this circumference. In particular, a region of the membrane can be exposed through this recess and can be accessible for reaction media.

[0034]Optionally, the side on which the first separating layer has a plastic layer is the side of it that is adjacent to the membrane.

[0035]According to one variant, the material of the plastic layer is different from a remaining material of an associated separating layer, with the exception of an optional further plastic layer on the side of this separating layer that faces away from the membrane. The remaining material of the associated separating layer can, for example, be homogeneous. It can be a stiffer material than that of the plastic layer, for example a stiffer plastic. According to the embodiments explained below, however, it can be a metallic material in particular.

[0036]The increased structural rigidity of at least the first or both separating layers can reduce the described risks of the prior art with regard to unfavorable deformations, lack of support and/or damage. For example, the fact that a structurally rigid separating layer spans the channels of an opposing distribution region can at least partially compensate for reduced structural support of the separating layer by these channels. In addition, the plastic layer provides reliable electrical insulation.

[0037]In this way, the separating layers can enable reliable and, in particular, safely sealed operation of an electrolyzer compared to existing insulation layers and/or existing cell frames.

[0038]According to a further development, the structurally rigid layer surrounds a recess in the manner of a frame. For example, this can be a central recess and/or a recess that exposes the membrane at least in regions, as described above. The structurally rigid layer can have a ridge adjacent to the recess, at least in sections. Accordingly, this can form an edge region or an edge of the recess or can be surrounded by it.

[0039]According to one embodiment, the structurally rigid layer is oriented in such a way that the ridge faces away from the membrane. For example, the ridge can protrude in only one direction in relation to the structurally rigid layer. No comparable ridge can protrude in the corresponding other direction, i.e. this side of the structurally rigid layer can be essentially flat or at least flatter than the side with the ridge. In summary, there can therefore be only a single one-sided ridge adjacent to the recess, which also protrudes in only one direction. The direction in which the ridge protrudes can, for example, be orthogonal to a plane of the structurally rigid layer and/or to a plane of the recess and/or its opening cross-section.

[0040]The fact that the ridge faces away from the membrane reduces the risk of damage to the membrane, especially if the media-carrying spaces of the cell arrangement are pressurized.

[0041]According to a further development, the structurally rigid layer comprises metal and optionally a metal sheet. This can be coated on at least one side by the plastic layer. The ridge can be a metal ridge. The ridge can also be at least partially plastic-coated, for example because a recess adjacent to the ridge is punched out of the coated metal sheet to create the ridge after the plastic layer has been applied.

[0042]According to one variant, the structurally rigid layer and/or a respective separating layer as such, apart from the at least one plastic coating, is formed entirely by a metal material, for example a metal sheet.

[0043]The use of metal, and in particular a metal sheet, is a cost-effective, easy to manufacture and reliable way of achieving increased structural rigidity of the separating layers.

[0044]In general, the structurally rigid layer can be formed congruently with the plastic layer. The optional metal of the structurally rigid layer can extend within the overall surface of the structurally rigid layer or form this overall surface. Consequently, the metal can also span the channels of the distribution region and/or extend over a large area from the frame-like surrounded recess to the outermost edge of the structurally rigid layer. Consequently, the metal cannot merely form a local reinforcing structure that is only embedded in certain regions of another optional material of the structurally rigid layer, for example. Instead, the metal/metal sheet forms the structurally rigid layer as such and/or in its entirety and/or spans the entire surface of the structurally rigid layer.

[0045]According to a further development, at least the first separating layer and/or the membrane, possibly only an edge region of the membrane, completely covers the distribution region whose channels are spanned. This can apply, for example, when considering an orthogonal projection along a stack axis, in which the separating layer, membrane and distribution region are projected into a common plane. In this way, a lack of structural support of the separating layer in the region of the channels, at least in some regions, can be at least partially compensated for.

[0046]According to a further development, the plastic layer comprises a polyester, for example polyethylene terephthalate, PET, or polyethylene naphthalate, PEN, a polyimide, PI, or a polyether ether ketone, PEEK. These materials allow for reliable electrical insulation with a process-safe layer-like application and a small layer thickness.

[0047]According to a further development, the plastic layer comprises a plastic film that is laminated onto the structurally rigid layer. For example, the plastic film is bonded to the structurally rigid layer using an adhesive, for example an acrylic adhesive. This simplifies the production of the separating layers disclosed herein and makes it possible, for example, to punch out the frame-shaped recess from a separating layer in an already laminated state. This creates a material bond between the structurally rigid layer and the plastic layer.

[0048]According to a further development, at least the first separating layer also has a plastic layer on a side that faces away from the membrane, at least in sections. This further plastic layer can be formed in the same way as the plastic layer on the side of the separating layer that is in contact with the membrane. This allows the material of the structurally rigid layer to be additionally electrically insulated and/or protected from contact with reaction media. This can reduce the requirements for the mechanical and/or chemical resistance of the material of the structurally rigid layer.

[0049]According to one embodiment, the structurally rigid layer is made of stainless steel or a titanium alloy, which in turn can be formed as a metal sheet. Stainless steel is characterized by high mechanical strength at a lower cost than titanium, whereas titanium has a higher corrosion resistance combined with low weight and at least sufficient mechanical strength.

[0050]According to a further embodiment, at least the first separating layer is topography-free. This can be understood to mean an essentially flat and/or planar configuration of the separating layer. In particular, the freedom from topography can be present at least in a non-installed state. As a result of elastic deformations during installation, however, non-planar deformations of the separating layer can occur, at least in some regions. In particular, the freedom from topography can include the absence of any intended and/or production-related embossing or other intended and/or production-related structuring on the outer sides of the separating layer. An exception may be a ridge, as explained below, and for example a metal ridge.

[0051]According to a further development, the structurally rigid layer is at least twice as thick or at least three times as thick as the plastic layer, i.e. as the plastic layer applied to at least one of its surfaces. This deliberately increases the proportion of the material/layer that primarily contributes to structural rigidity compared to the plastic layer. This can be a stainless steel layer with a laminated PEN adhesive film, for example.

[0052]Another general finding of the present disclosure is that a comparatively thin plastic layer is sufficient to achieve electrical insulation. The space freed up within the electrochemical cell arrangement can thus be taken up by a structurally rigid layer with a corresponding thickness. This results in an overall increase in rigidity along with the associated benefits.

[0053]According to a further development, the plastic layer has a thickness of less than 0.3 mm and optionally less than 0.1 mm and furthermore optionally less than 0.05 mm. It has been shown that reliable electrical insulation can be achieved even with such low thicknesses. As described above, a thickness of the structurally rigid layer can be increased by reducing the thickness of the plastic layer, without increasing the overall height of the separating layer and/or the cell arrangement.

[0054]A further embodiment provides that the side of each of the first and second separator plate closest to the first separating layer has a seal on its side that faces the first separating layer, which bears against the first separating layer, and/or wherein the side of the first and second separator plate closest to the second separating layer has a seal on its side that faces the second separating layer, which bears against the second separating layer.

[0055]For example, the seal can be used to fluidically seal the electrochemical cell arrangement from an adjacent through-opening and/or from the outside world. The increased structural rigidity of the separating layers disclosed here can generally improve the reliability of contact pressure on the seal and thus fluidic sealing in general.

[0056]The present disclosure also relates in principle to an electrochemical system comprising a plurality of cell arrangements according to any of the aspects disclosed herein, for example in a stacked arrangement.

[0057]Also disclosed as an in principle claimable part of the present disclosure is a method of manufacturing an electrochemical cell arrangement according to any variant disclosed herein. Variants and further developments described in the context of the cell arrangement can also apply to the method, in particular to its identical features.

[0067]According to a further development of the method, the plastic layer of the first separating layer is in contact with the membrane. Optionally, however, neither the plastic layer nor the separating layer are connected to the membrane, neither in a form-fit manner nor in a materially bonded manner. For example, the adjacent components can be free of molded elements by means of which a mechanical and, for example, form-fit coupling could be produced between them. A form-fit connection between the separating layer and the membrane would only be created during stack assembly by applying compression when tightening the screws and positioning the layers in relation to each other using positioning pins.

[0068]In this context and/or generally in the context of the present disclosure, contact can mean in particular that there is contact between two adjacent components, such as the membrane and separating layer or between membrane and plastic layer, but not a connection, in particular not of the form-fit and/or material bond type mentioned above and/or in particular without a permanent joining. A contact can thus in particular comprise a contact, especially a non-adhesive and/or non-destructive detachable contact. However, this contact can be free of mechanical and/or chemical bonds between the adjacent components, especially before the stack is tensioned.

[0069]According to a further development, the method for producing the frame-shaped structurally rigid layer further comprises: punching out or otherwise separating out a section from a structurally rigid layer of material having a plastic layer, to create a frame-shaped recess. In this context, a ridge may be formed according to any variant disclosed herein, for example as a result of punching out.

[0070]Accordingly, the arranging may also include: Arranging the structurally rigid layer in such a way that a ridge created during its manufacture faces away from the membrane.

[0071]Examples of embodiments of the present disclosure are shown in the attached figures and are explained in more detail in the following description. The same reference symbols can be used for identical or comparable features across all figures. Within a figure, only selected instances of a feature may in principle be provided with a reference sign assigned to this feature.

BRIEF DESCRIPTION OF THE FIGURES

[0072]FIG. 1 shows a first side of a separator plate as it can be used in a cell arrangement according to the present disclosure.

[0073]FIG. 2 shows a second side of the separator plate from FIG. 1.

[0074]FIG. 3 shows an exploded view of a cell arrangement according to an embodiment of the present disclosure.

[0075]FIG. 4 shows the cell arrangement from FIG. 3 in the assembled state.

[0076]FIG. 5 shows a perspective partial sectional view of the cell arrangement from FIG. 4.

[0077]FIG. 6 shows a detailed view of a separating layer of the cell arrangement from FIGS. 3-5.

[0078]FIG. 7 shows a side view of a section of FIG. 5.

DETAILED DESCRIPTION

[0079]FIG. 1 shows a first side of an exemplary separator plate 10, as can be used in a cell arrangement 12 according to the present disclosure, see FIG. 3. The side shown corresponds to an anode side. FIG. 2 shows the second side of the exemplary separator plate 10 from FIG. 1. This side corresponds to a cathode side.

[0080]Selected features of the separator plate 10 are explained below with reference to FIGS. 1 and 2. The exemplary separator plate 10 has a non-limiting rectangular shape. It comprises a single metallic layer that, for example, consists at least predominantly of or entirely of titanium or stainless steel or alloys thereof. The metallic layer 10 can, for example, have a thickness of at least 0.1 mm, optionally at least 0.25 mm and/or at most 0.8 mm, optionally at most 0.5 mm.

[0081]With reference to FIG. 1 below, the separator plate 10 has a flow field 14 on its first side, shown in this figure. This is configured to distribute water, which is supplied from first through-openings 16 near a first side of the flow field 14, over a large area and to guide it in the direction of flow to first through-opening 16 near an opposite second side of the flow field 14. In FIG. 1, the direction of flow is from bottom left to top right or vice versa. The flow field 14 is connected in a fluid-conducting manner to the first through-openings 16 via a respective distribution region 22 on the first and opposite side of the flow field 14 as described.

[0082]A channel structure 18 is provided in the flow field 14. The individual channels or recesses 20 of the channel structure 18 are separated from each other by webs or protrusions 21, see FIG. 5 below. The flow field 14 forms an electrochemically active region on the corresponding side of the separator plate 10. The distribution regions 22 lie outside this electrochemically active region.

[0083]The distribution regions 22 also each comprise a channel structure 18′. The individual channels/recesses 20′ of the channel structure 18′ are separated from each other by webs/protrusions 21′, see FIG. 5. The flow field 14 is optionally separated from an adjacent distribution region 22 by a transition region 24. This is lowered in relation to the web crests of the flow field 14 and the distribution region 22, see FIG. 5.

[0084]The separator plate 10 also comprises second through-openings 16′. These in turn are arranged on or close to opposite sides of the flow field 14, but on different sides than the first through-openings 16. More specifically, in FIG. 1, optionally a plurality of first through-openings 16 are arranged near and/or opposite to an upper and lower side of the flow field 14 (or generally a first and second side) and optionally a plurality of second through-openings 16′ are arranged near and/or opposite to a left and right side of the flow field 14 (or generally a third and fourth side). The second through-openings 16′ are not connected to the flow field 14 in a fluid-conducting manner on the separator plate side shown due to the lack of a distribution region 22. Rather, the second through-openings 16′ on the side of the separator plate 10 in FIG. 1 that faces the observer are sealed off from the flow field 14.

[0085]FIG. 2 shows that such a fluid-conducting connection is made on the second side of the separator plate 10 via distribution regions 22′. These distribution regions 22′ are generally analogous to the distribution regions 22 on the first side of FIG. 1 and connect the second through-openings 16′ with the flow field 14′ on this second side.

[0086]On the other hand, the distribution regions 22 on the first side are not also present on the second side. On this second side, the first through-openings 16 to the flow field 14′ are sealed. This means that the first through-openings 16 are not connected to the flow field 14′ on the second side in a fluid-conducting manner.

[0087]The flow field 14′ of the second side has a channel structure 18″ that is complementary to the flow field 14 of the first side. Despite an orientation of the channels and webs orthogonal to a flow direction between the through-openings 16′, the flow field 14′ can easily be overflowed by the hydrogen guided on this side in a manner known per se, i.e. also by means of flow through the GDL not shown here. Consequently, the second through-openings 16′ are designed to discharge hydrogen.

[0088]FIG. 3 shows an exploded view of an electrochemical cell arrangement 12 according to an exemplary embodiment according to the present disclosure. The cell arrangement 12 is part of an electrochemical system in the form of an electrolyzer. Electrolyzers typically comprise a large number of such cell arrangements 12 stacked on top of each other. A stack axis S, along which the individual components of the cell arrangement 12 are stacked and pressed together, is shown. Along this stack axis S, other cell arrangements 12 of an electrolyzer, which are not shown, are also stacked on top of one another together with the cell arrangement 12 shown and are pressed together.

[0089]The cell arrangement 12 comprises two separator plates 10, 10′, as explained with reference to FIGS. 1 and 2. These are arranged in such a way that one of the separator plates 10, 10′ has a first side facing the interior of the cell arrangements 12 and/or the corresponding other separator plate 10, 10′, and the other separator plate 10, 10′ has the second side facing the interior of the cell arrangements 12 and/or the corresponding other separator plate 10, 10′. The outward-facing sides of the separator plates 10, 10′ cannot be regarded as an actual component of the cell arrangement 12. For example, they can be assigned to neighboring cell arrangements 12 that are not shown and/or delimit them.

[0090]In the case of FIG. 3, the second side of the upper separator plate 10 as shown in FIG. 2 faces inwards as part of the cell arrangement 12. In the case of the lower separator plate 10′, the first side as shown in FIG. 1 faces inwards as part of the cell arrangement 12.

[0091]A separating layer 26, 26′ lies against a respective inwardly facing side of each separator plate 10, 10′ and forms a component of the cell arrangement 12. The separating layers 26 each have a central recess 27, which surrounds them in the manner of a frame. The separating layers 26, 26′ are, apart from any deformations in the installed state, flat and topography-free components that extend parallel to the separator plate 10, 10′.

[0092]A membrane 28 having media diffusion structures 30 on both sides is arranged between the separating layers 26, 26′. The latter include, for example, a GDL and/or a PTL. The membrane 28 has a membrane surface 29 at least opposite the recesses 27 of the separating layers 26, 26′, for example comprising a proton exchange membrane (PEM) comprising a polymer material. A circumferential reinforcing edge 31 runs along the outer edges of the membrane surface 29.

[0093]An orthogonal projection of the membrane surface 29 along the stack axis S onto the separator plates 10, 10′ defines their electrochemically active regions and respective flow fields 14, 14′.

[0094]Finally, it should be noted that the separation layers 26, 26′, and also the membrane 28, comprise fluid passages 32 that are aligned with the through-openings 16, 16′ explained with reference to FIGS. 1 and 2. Selected ones of these fluid passages 32 are marked with a corresponding reference sign as an example for the uppermost separating layer 26. Also shown are recesses 34 provided within the separating layers 26, 26′, the separator plate 10, 10′ and the membrane 28 for the passage of fastening elements (not shown separately). Selected ones of these recesses 34 are marked with a corresponding reference sign in the lower part of FIG. 3.

[0095]FIG. 4 shows the cell arrangement 12 from FIG. 3 in the assembled and, in particular, pressed state. Additional neighboring cell arrangements 12 are shown, which form an exemplary stack of three cell arrangements 12. It can be seen that the separating layers 26, 26′, separator plates 10, 10′ and the membrane 28, which are not marked separately here, are arranged substantially congruently to one another within a respective cell arrangement 12.

[0096]Furthermore, the position of a sectional plane A-A is marked in FIG. 4. The resulting partial sectional view is shown in FIG. 5. The structure of the uppermost cell arrangement 12, and in particular of the separating layers 26, 26′, is explained in more detail below with reference to FIG. 5. A particularly relevant region of FIG. 5 is framed by a dashed line; this is shown in more detail in FIG. 7. The designation of the separator plates 10, 10′ with the corresponding reference symbols refers to the orientations shown in FIG. 3.

[0097]It can be seen that the solid regions of the separating layers 26, 26′ are positioned outside the flow fields 14, 14′. The recesses 27 are located there, that is, opposite the flow fields 14, 14′.

[0098]In the example shown, the uppermost separating layer 26 and, more precisely, a solid region thereof is located opposite, inter alia, a region of the uppermost separator plate 10 that faces away from the distribution region 22 or is formed on the inner side thereof. This region of the separator plate 10 is complementary to the distribution region 22. An elastomer seal 36 is arranged in this region and lies against the opposite outer side of the separating layer 26. By way of example, this elastomer seal 36 comprises two sealing lips 38 protruding in the direction of the insulating layer 42. The side of the upper separating layer 26 that faces away from the elastomer seal 36 is in contact with the membrane 28.

[0099]Also shown is the lower separating layer 26′, which lies against the side of the membrane 28 that faces away from the upper separating layer 26. With its corresponding other side, the lower separating layer 26′ lies against the distribution region 22 of the nearest and, in FIG. 5, lower separator plate 10′ of the uppermost electrochemical cell arrangements 12. In this case, a section 50 of the separating layer 26′ spans, or in other words covers, the channels 20′ of this distribution region 22 along their entire length L. The latter is shown as an example for the lowest separator plate 10′.

[0100]The channels 20′ form regions of missing structural support of the separating layer 26′ by the adjacent separator plate 10′. However, as explained below with reference to FIG. 6, this lack of structural support can be at least partially compensated for by the separating layers 26, 26′ formed according to the present disclosure.

[0101]FIG. 6 shows an example of the structure of the separating layers 26, 26′. FIG. 6 is a partial sectional view, with the sectional plane running perpendicular to the layer plane of the depicted separating layer 26, 26′. The sectional region shown here comprises an edge region adjacent to the recess 27 of the separating layers 26, 26′. The fact that the separating layers 26, 26′ of the described embodiment are configured in the same way is merely exemplary. This is therefore not mandatory.

[0102]The separating layers 26, 26′ each comprise a structurally rigid layer 40 made of metal, such as titanium or stainless steel, and more specifically of a metal sheet. This is coated on both sides with a plastic layer 42, which in the illustrated example comprises PEN. The plastic layers 42 cover the entire surface of each respective outer side of the layer 40, so that they are electrically insulated from the surroundings. In addition, the plastic layers 42 have a protective function against mechanical and chemical damage to the layer 40.

[0103]A thickness dimension of the layer 40, running vertically in FIG. 6, clearly exceeds a respective thickness of the plastic layers 42 and in the illustrated example is at least four times as large. Thus, the structurally more rigid component of the separating layers 26, 26′ in the form of the layer 40 takes up a deliberately increased proportion of the volume and especially of the thickness of the separating layers 26, 26′. These are therefore mechanically stiffened in a targeted manner. On the other hand, it was recognized that the thickness of the plastic layers 42 can be comparatively significantly reduced without impairing their electrically insulating effect.

[0104]In the example shown, the metal sheet is received in a state in which it is already coated on both sides and is processed further, for example as sheet or strip material. Individual separating layers 26, 26′ and their recesses 27 are punched out of this. As a result, a one-sided metal ridge 44 is formed on the inner edge bounding the recess 27 or, in other words, on the inner edge of the recess 27. However, there is no comparable metal ridge 44 on the corresponding opposite side of the separating layers 26, 26′, see FIG. 6.

[0105]As shown in FIG. 7, the separating layers 26, 26′ are oriented such that their metal ridges 44 each face away from the membrane 28 received between them. This can be seen from the regions framed with dashed lines in FIG. 7. In this way, damage to the membrane 28 by the metal ridge 44 is avoided.