Separator plate for electrochemical system and electrochemical system

Abstract

The invention relates to a separator plate for an electrolyzer or for another electrochemical system. Furthermore, the invention relates to an electrochemical system.

Description

[0001] The invention relates to a separator plate for an electrolyzer or for another electrochemical system. Furthermore, the invention relates to an electrochemical system.

[0002] Electrochemical systems often comprise a stack of separator plates and elements arranged between them, such as membrane electrode assemblies (MEAs). The separator plates comprise through-openings, each of which is fluidically connected to a fluid channel of the electrochemical system and / or delimits a section of this channel. The through-openings or fluid channels can, for example, supply fuels (e.g., hydrogen or methanol), reaction gases (e.g., air or oxygen), or a cooling medium to the electrochemical system and / or remove reaction products and heated cooling medium from the system. In the case of electrolyzers, water can be supplied and oxygen and hydrogen can be removed.

[0003] The supplied fluids should generally only exit or enter the through-holes on one side of the separator plate, in particular to flow along the corresponding side of the separator plate. Such exit or entry should be prevented on a correspondingly different side of the separator plate. For this purpose, seals are used, which, for example, surround the through-hole carrying this fluid, in particular in a ring-shaped manner.

[0004] As a rule, it is provided that on one side of a separator plate (or a bipolar plate comprising a plurality of separator plates) a first fluid can exit from or enter an associated through-opening and on the corresponding other side a different second fluid can exit from or enter a correspondingly associated through-opening.

[0005] An established type of seal involves those that are elastically deformable during assembly, particularly during clamping or pressing, or even during the closing of the electrochemical system, and that are made of a non-metallic material, particularly elastomer seals. Such seals can, for example, be molded directly onto a corresponding side of the separator plate.

[0006] It has been shown that the desired sealing effect of previous solutions is not always sufficiently reliable.

[0007] The present application is therefore directed to the task of improving the fluidic sealing of separator plates of electrochemical systems and in particular of their through-openings.

[0008] This object is achieved by the subject matter of the independent claims. Advantageous further developments are specified in the dependent claims, in this description, and in the figures.

[0009] Accordingly, a separator plate for an electrolyzer or other electrochemical system is proposed, the separator plate comprising a plate component comprising: • a first side and a second side facing away from it, • a flow field on each of the first and second sides, • several distribution areas with a plurality of channels, with two adjacent channels being separated by a web, and • a plurality of through openings, wherein the through-openings are each connected on one of the first and second sides in a fluid-conducting manner via one of the distribution areas to the flow field of this side and are each fluidically sealed on the corresponding other of the first and second sides by a seal of the separator plate with respect to the flow field of this side, wherein at least one of the seals extends at least partially along an edge region of the through-opening sealed by this seal and has at least one outer surface which, at least in a state uninstalled in the electrochemical system, is at least partially topographical along this longitudinal extent and / or has a varying height profile.

[0010] The seal can be created or formed by an elastomer profile that is injection-molded, inserted, glued, knotted or applied to the separator plate.

[0011] According to the invention, it was recognized that a previous lack of sealing effectiveness can result, for example, from the seals being unevenly compressed along their length. The separator plates typically have large distribution areas provided with channels, against which the seals of an adjacent separator plate are at least indirectly supported. For example, additional components, in particular elastically deformable cell frames or MEAs, can be arranged between the separator plates, and the seal can be indirectly supported on an adjacent separator plate via these components.

[0012] If a seal of a first separator plate rests against such a channeled distribution area of ​​an adjacent second separator plate and / or rests against a channeled distribution area of ​​the separator plate to which the seal is attached and, for example, molded, the seal may be subjected to irregular loads and thus deformed accordingly. This can impair the sealing effect. Such a restraint can occur, in particular, as a result of distortion of the electrochemical system during assembly.

[0013] Instead, it is proposed here to topographically design the seal, which in the prior art typically has a completely flat outer surface, at least in sections and, in particular, to provide it with a varying height profile. This can, for example, at least partially compensate for the unevenness of the channels and webs of a distribution area of ​​an adjacent separator plate, against which a seal is at least indirectly supported.

[0014] The topographical design can, in particular, be implemented in at least one section of the seal that runs along an uneven section of the separator plate, such as a distribution area with channels and webs, and / or that is opposite or facing an uneven section of an adjacent separator plate. Preferably, a topographical design of the type disclosed here is present in the majority or all such sections of the seal.

[0015] Separator plates disclosed herein can be single-layer separator plates whose plate components are formed, for example, from a single section of material, in particular a sheet material. However, the separator plates can also each have two individual plates (i.e., two individual plate components) that are firmly connected to one another, for example, by welding. The separator plates serve, for example, to electrically contact the electrodes of the individual electrochemical cells (e.g., fuel cells) and / or to electrically connect adjacent cells (series connection of the cells). In these cases in particular, they are also referred to as bipolar plates. The separator plates can also serve to dissipate heat that arises in the cells between the separator plates. Such waste heat can arise, for example, during the conversion of electrical or chemical energy in a fuel cell.

[0016] The electrochemical system can, as mentioned, be an electrolyzer, but in particular also a fuel cell system, an electrochemical compressor or a redox flow battery.

[0017] The channels and webs of the distribution areas, which can be encompassed by and / or partially form a media guide structure, can be designed to supply an active area of ​​each separator plate and / or individual plate with one or more fluids or media and / or to transport fluids or media away. In particular, the channels can guide the fluids and be delimited by the webs. The active area of ​​a separator plate and / or individual plate can enclose or delimit an electrochemical cell. In fuel cells, the reaction media, i.e. fuel and reaction gases, are usually guided on the opposite sides of the separator plate, while a coolant is guided between the individual plates of the separator plate.In an electrolyzer, reaction media are also carried on the opposite sides of the separator plate, whereas the carrying of coolant between any individual plates, if present at all in an electrolyzer, can be omitted.

[0018] The through-openings can be formed according to the aspects of the prior art discussed above. The through-openings of the separator plates can be aligned with one another in a stack of separator plates. Alternatively or additionally, they can be arranged so as to overlap one another at least in sections. Alternatively or additionally, the through-openings can jointly define and / or at least partially delimit a fluid channel.

[0019] The fluid connection of a through-hole to the flow field may include the possibility of fluid conduit between these features without these features necessarily having to be structurally integrated and / or directly connected to one another.

[0020] The through-openings can be molded into the material of the separator plate and, in particular, of its plate component or cut out of it. In general, the at least one plate component can be a one-piece component, preferably formed from a homogeneous material, in particular a metallic material. Beyond this one-piece, homogeneous component formed from a single material, the plate component can, however, have coatings. Furthermore, the separator plate can also be made of plastic.

[0021] Like the distribution areas, the flow field may include channels and webs and / or be part of a media guidance structure. Alternatively, the flow field may be free of such structures and, in particular, be flat or, in other words, smooth.

[0022] The channels and webs of the distribution areas and / or the flow field can be formed into the plate component, for example, by hydroforming, embossing, and / or deep drawing. For the purposes of this disclosure, the terms "embossing" or "embossed" can be understood to mean, in particular, hydroforming, roll embossing, stroke embossing, and / or deep drawing.

[0023] The seal can be positioned and / or extend such that fluid exiting the through-opening sealed by it can enter at least a portion of a distribution region associated with this through-opening. This can in particular be a region close to and / or immediately adjacent to and / or transitioning into the through-opening. The seal can, for example, fluidically separate this portion from another portion of the distribution region and / or from the flow field. In particular, the seal can run at least partially in the region of one of the distribution regions and / or overlap and / or cross it. According to one variant, such a distribution region is positioned adjacent to the through-opening sealed by the seal or directly adjoins it.

[0024] A distribution area assigned to a through-opening can be understood, for example, as a distribution area that is configured and, in particular, positioned to directly receive a fluid emerging from the through-opening or, in particular, to introduce fluid directly into the through-opening. In particular, the assigned distribution area can be directly adjacent to the through-opening or positioned at a distance of less than 5 cm, and in particular less than 2 cm, from it, which can also be 0 cm. Alternatively or additionally, the assigned distribution area can be the distribution area from the plurality of distribution areas that is closest to the through-opening.

[0025] The seal can consist of or be formed from an elastomer that is injection-molded onto the separator plate. The elastomer can contain or consist of FKM (fluoroelastomer), silicone rubber or NBR rubber (nitrile butadiene rubber), PUR (polyurethane), NR (natural rubber), FFKM (perfluoro rubber), SBR (styrene butadiene rubber), BR (butadiene rubber), FVMQ (fluorosilicone), CSM (chlorosulfonated polyethylene), HNBR (hydrogenated nitrile butadiene rubber), ACM (acrylate rubber), AEM (acrylate ethylene rubber), EPDM (ethylene propylene diene rubber), IIR (butyl rubber), or mixtures of the aforementioned materials. However, the present invention is not limited to these materials. Alternatively, the elastomer profile could also be manufactured using other processes.

[0026] The outer surface can be encompassed by at least one sealing lip of the seal. As explained below, the seal can have multiple sealing lips, each of which can have an outer surface and, in particular, a topographically shaped outer surface of the type disclosed here. This is particularly evident in the uninstalled or unclamped state of the separator plate.

[0027] The outer surface may define a surface of the seal that largely or entirely abuts an adjacent component. This component may be, for example, an MEA or a cell frame as explained below. The outer surface may be the only surface of the seal that enables such abutment. If there are multiple outer surfaces, for example, due to the provision of multiple sealing lips, these outer surfaces may be the only surfaces of the seal that enable such abutment of the seal.

[0028] The seal can largely and in particular completely surround the associated through-opening (i.e. the through-opening that is sealed by the seal). Consequently, it can also largely or completely surround an edge region of the through-opening. An extension of the seal along the edge region does not necessarily require a constant distance to this edge region. Such a distance can, for example, be measured parallel to the plate plane. According to embodiments, however, a correspondingly constant distance can be provided. Also, the extension of the seal along the edge region does not require a completely parallel extension to this edge region, which can, however, also be provided according to embodiments.

[0029] In particular, an extension of the seal along the edge region can be understood to mean that a local extension direction of the seal has a vector component that runs parallel to an extension direction of an adjacent section of the edge region. This vector component can, for example, be larger than a vector component that runs orthogonal to the extension direction of the adjacent section of the edge region.

[0030] Any reference herein to a separator plate may be considered synonymous with a reference to its plate component(s), and in particular exclusively to that plate component, unless otherwise stated or apparent. As mentioned, a separator plate may optionally also comprise a plurality of plate components of the type disclosed herein.

[0031] A topographical outer surface or a general topographical surface can be understood as a surface topography. In particular, this can be synonymous with an uneven and / or not consistently flat surface shape.

[0032] In particular, a topographical outer surface can be understood to have a varying height profile. The height profile can extend along a height axis. This can run orthogonal to the longitudinal extent of the seal and / or to a flat surface plane of the separator plate. The varying height profile can comprise varying heights or, in other words, varying positions of the outer surface with respect to this height axis, wherein this variation occurs in particular when viewed along the longitudinal extent of the seal. In other words, viewed along this longitudinal extent, seal sections of different and thus varying heights can follow one another. In this case, the same deflection with respect to the height axis does not always have to be achieved with variations.

[0033] In a manner known per se, the plane of the separator plate can be defined, for example, by an edge of the separator plate and / or its plate component or by those flat areas of a separator plate and / or its plate component that are not deformed as a result of an embossing or deep-drawing process to form the media conduction structure described herein and in particular the distribution areas or other embossed or deep-drawn structural features. On the one hand, the planes of the planes of the separator plate and / or its plate component can run in the neutral fibers of the corresponding sections of the separator plate and / or its plate component; on the other hand, it is also possible to consider the surfaces of the relevant sections of the plates as planes of the planes of the separator plate. With the latter approach, however, it must be ensured that when considering distances or the like, the material thickness of only one of two individual plates under consideration is taken into account, if present.

[0034] A state of a separator plate installed in the electrochemical system can include that it has been mechanically clamped. In the manner described below, the electrochemical system can comprise a plurality of separator plates, in particular stacked one above the other, wherein the stack is mechanically clamped in a manner known per se. As a result of such clamping, the seal can be elastically deformed and the topographical configuration of the outer surface of the seal can be compressed accordingly. In particular, any varying height profile of the seal can be adjusted to a more uniform height, at least in sections and / or at least partially. However, this can be advantageous for achieving a reliable sealing effect, and the topographical outer surface disclosed here can specifically promote the achievement of such a uniform height in the installed and, in particular, clamped state.

[0035] According to one embodiment, the outer surface is shaped similarly to a region of the corresponding first and second side on which the seal is arranged and along which the outer surface extends. This can apply in particular with regard to a height profile and / or a surface shape and / or surface topography of the outer surface and this region. For example, the outer surface can be similarly corrugated, curved or generally profiled to the aforementioned region. The similarity can relate in particular to the general shape of the outer surface and the corresponding region, for example in the sense of a corrugated, rectangular or sawtooth shape or generally an alternating sequence of similar shape and / or surface features. It can be provided, but is not mandatory, that the exact dimensions of this shape or of the respective surface profiles also essentially match.These dimensions can, for example, be amplitudes and / or period widths of alternating shape features, such as elevations and depressions. It has been shown that pressure conditions can be uniformed by means of such uniform shaping.

[0036] This applies in particular in cases where the side of the separator plate on which the seal is arranged is shaped complementarily to a side of an adjacent separator plate, for example, which follows in a stacking direction. For example, in this case, the outer surface of the seal can be locally recessed, but in the stacking direction, it can be opposite or face a complementarily raised region of the adjacent separator plate. Additionally or alternatively, the outer surface of the seal can be locally raised, but in the stacking direction, it can be opposite or face a complementarily recessed region of the adjacent separator plate.Thus, the height profiles of the outer surface of the seal and of opposing regions of the adjacent separator plate can equalize at least partially, which can even out the resulting pressure conditions during assembly and, in particular, clamping of the electrochemical system. Furthermore, the topographical outer surface of the seal can also be geometrically phase-shifted in the longitudinal direction, i.e., in particular, geometrically phase-shifted to a side of an adjacent separator plate following in a stacking direction.

[0037] According to a further embodiment, the region to which the outer surface of the seal is shaped similarly comprises a part of one of the distribution regions of the corresponding first and second sides. Accordingly, the seal can cross the distribution region or its web-channel structure at least in sections, for example in the manner described above. For example, sections of the seal or of its outer surface can extend transversely to the longitudinal channel axes of the distribution region or of its web-channel structure. Such a distribution region, which is crossed by the seal, for example, preferably does not establish a fluid-conducting connection between a through-opening and the flow field. Instead, such a connection is deliberately interrupted by the seal. Such a distribution region can be shaped complementarily to a distribution region on the opposite side of the separator plate.This opposing distribution area can specifically establish a fluid-conducting connection. The fluid-sealed distribution area can result from a stamping or other forming process used to create the opposing fluid-conducting distribution area.

[0038] According to a further embodiment, the outer surface of the seal faces away from the corresponding first and second sides on which the seal is arranged. Additionally or alternatively, the outer surface of the seal can be configured to be brought into contact with another component (e.g., an MEA or a cell frame) of the electrochemical system, which extends at least partially parallel to and / or directly opposite the separator plate. Additionally or alternatively, the outer surface of the seal can extend along a flat surface plane of the plate component.

[0039] According to one embodiment, the height profile varies alternately, at least in sections. For example, the height profile can have an alternating sequence of elevations, preferably of similar dimensions, at least in the height direction, and depressions, preferably of similar dimensions, at least in the height direction, in particular along the longitudinal extent of the seal. The alternating sections can be evenly spaced from one another. This can correspond to a regular and / or periodic alternation. However, they can also be irregularly spaced from one another. This can, for example, accommodate varying web and / or channel widths of the distribution area.

[0040] According to one embodiment, the outer surface of the seal is corrugated at least in sections. This can be understood, in particular, as a topography of the outer surface that comprises an alternating sequence of wave troughs and wave crests. The transitions between these alternating sections can be rounded. The wave shape can represent a particularly suitable adaptation to adjacent regions of the separator plate or opposite regions of an adjacent separator plate (and / or to regions of an adjacent separator plate toward which the outer surface faces) for the purpose of pressure equalization.

[0041] As mentioned, a height dimension of the seal can extend orthogonally to a flat surface plane of the plate component.

[0042] According to one embodiment, a height difference between a locally lowest point of the outer surface of the seal and the adjacent locally highest point of the outer surface is between 0.01 mm and 1 mm. A lower limit of this range can alternatively be 0.2 mm. An upper limit of this range can alternatively be 0.8 mm. In particular, the said range can therefore be between 0.2 mm and 0.8 mm.

[0043] According to one embodiment, a distance along the longitudinal extent of the seal between a locally lowest point of the outer surface and the adjacent locally highest point of the outer surface is between 0.1 mm and 2.5 mm.

[0044] Any locally lowest point disclosed herein may be comprised of a depression and / or a trough of an alternating elevation profile or topography of the type disclosed herein. Any locally highest point disclosed herein may be comprised of an elevation and / or a crest of an alternating elevation profile or topography of the type disclosed herein.

[0045] It has been shown that reliable sealing effects can be achieved with the height differences and distances mentioned above.

[0046] According to a further embodiment, the seal has at least two sealing sections protruding from the plate component, for example in the form of sealing lips, which can run parallel to one another. Each of the sealing sections can have an outer surface that, at least in a state uninstalled in the electrochemical system, is topographical in the direction of its longitudinal extent and at least in sections and / or has a varying height profile.

[0047] The invention also relates to an electrochemical system, in particular an electrolyzer, comprising a plurality of separator plates according to any of the aspects disclosed herein, wherein the separator plates are arranged in a stack. For example, the separator plates can be stacked one above the other along a stack axis. The separator plates can be aligned parallel to one another. Further components of the electrochemical system, in particular an MEA, a cell frame, a porous transport layer (PTL), or a gas diffusion layer (GDL), can be arranged between two separator plates immediately adjacent along the stack axis. In particular, such a stack, including any further components comprised thereby, can be mechanically stressed before the electrochemical system is put into operation. The deformations of the seals described herein can occur as a result of this stress at the latest.

[0048] In the electrochemical system, for each pair of adjacent separator plates, the at least one seal having the topographical outer surface can point from a first separator plate of this pair to a second separator plate of this pair. In particular, this seal can be supported on, or in other words, on, this second separator plate. This enables reliable, at least indirect, support of the outer surface of this seal on the second separator plate to achieve a reliable sealing effect.

[0049] According to one embodiment, the topographical outer surface of the at least one seal of the first separator plate is, at least in an unstressed state of the stacked separator plates, complementarily shaped to an opposite region and / or region of the second separator plate facing the outer surface. As a result of the stressing, the topography and / or the height profile of the separator plate can become more closely aligned with the topography and / or the height profile of the second separator plate. Alternatively or additionally, the topography and / or the height profile of the separator plate can become more uniform, for example, toward a more even shape.

[0050] "Opposite" can be understood here, in particular, as an at least indirect succession, the latter allowing the presence of further components between the opposing components. In particular, this can be understood to mean that the corresponding features face each other, for example, along a specific axis (in particular a stacking axis mentioned herein), even if further components may be positioned between them.

[0051] According to one embodiment, the at least one seal with a topographical outer surface of the second separator plate faces away from the first separator plate. This seal can, for example, be opposite and / or facing a third separator plate adjacent to the second separator plate. This embodiment can involve only one seal with a topographical outer surface being provided per through-opening between two adjacent separator plates (and more precisely between their plate components). This enables reliable sealing with a compact stack height.

[0052] According to one embodiment, at least one membrane electrode assembly (MEA) is arranged between the separator plates of each pair of adjacent separator plates. The seal of the first separator plate can directly contact the membrane electrode assembly. The seal of the first separator plate can be supported on the second separator plate via the MEA. Due to the pressure-equalizing effect of the topographical outer surface disclosed here, the seal can be supported on the MEA evenly and with a correspondingly uniformly reliable sealing effect.

[0053] According to a further embodiment, a cell frame is arranged between the separator plates of each pair of adjacent separator plates, in addition to the membrane electrode assembly and on both sides of the membrane electrode assembly, wherein the seal of the first separator plate abuts one of the cell frames. More specifically, the seal can abut the cell frame arranged on the side of the MEA facing the first separator plate.

[0054] In general, the cell frames may be planar components which may be arranged substantially parallel to the separator plates in a stack of the electrochemical system disclosed herein.

[0055] The cell frames can be of similar design. They can be assembled or combined to form an overall cell frame or interact as such. They can be considered partial cell frames of a corresponding overall cell frame. The cell frames can each have a receiving recess in which at least one further component of the electrochemical system is received and in particular is exposed and / or uncovered. This component can be, for example, the aforementioned MEA. The cell frames can each provide a stiffening function and in particular be stiffer than the received component and in particular the MEA. According to one variant, the cell frames comprise a plastic material, in particular polyethylene naphthalate, PEN. In general, a material of the cell frames can be different from the received component and in particular the MEA.

[0056] Receiving a component from and in particular between the cell frames can comprise at least one edge region of this component abutting the cell frames and / or being enclosed between them. The cell frames can surround or enclose the received component in a frame-like manner. This particularly applies to an inner circumference or inner edge of the aforementioned receiving recess, which can in particular be closed and / or have a correspondingly frame-like profile.

[0057] Embodiments of the invention are explained below with reference to the accompanying schematic figures. Similar or equivalent features may be provided with the same reference numerals throughout the figures. Within a given figure, not all instances of a feature shown may be provided with the reference numeral associated with that feature. Fig. 1 shows the basic structure of an electrochemical system in the form of an electrolyzer according to an embodiment of the invention. Fig. Figure 2 shows schematically a first side of a separator plate according to an embodiment of the invention, as used for example in the system of Fig. 1 can be used. Fig. Figure 3 shows schematically a second side of a separator plate according to an embodiment of the invention, as used for example in the system of Fig. 1 can be used. Fig. 4 shows a sectional view through a pair of separator plates stacked on top of each other in the unpressed state, wherein the separator plates are produced according to an embodiment of the invention and in particular according to the variants of Fig. 2 and Fig. 3 can be trained. Fig. 5 shows the pair of separator plates from Fig. 4 in compressed state. Fig. 6 is a partial perspective view of the separator plates in the state of Fig. 5. Fig. 7 shows a further example of a sectional view through a pair of separator plates stacked on top of each other in the unpressed state, wherein the separator plates according to an embodiment of the invention and in particular according to the variants of Fig. 2 and Fig. 3 can be trained. Fig. 8 shows the pair of separator plates from Fig. 6 in compressed state.

[0058] Fig. 1 shows an electrochemical system 10 according to an embodiment of the invention. The electrochemical system 10 is an electrolyzer. The basic structure of this electrolyzer explained here is known in principle. Modifications according to the invention disclosed here relate in particular to the design of the separator plates 18.

[0059] The electrolyzer comprises a stack of repeating component sequences, as explained below. The stack is arranged and clamped between two limiting plates 14, i.e., it is mechanically pressed together and compressed or braced. All components of the stack are stacked along a stacking axis S, or, in other words, lined up in a row.

[0060] Within the stack, bipolar plates 16 are provided, consisting of a separator plate 18, installed here in a single layer. Each separator plate 18 comprises a plate component 19 formed from a single metal sheet and, in particular, embossed and / or punched. The separator plate 18 also includes seals 33, explained below.

[0061] If reference is made below to a separator plate 18, this may be synonymous with a reference to its plate component 19 and in particular exclusively to the plate component 19, unless otherwise stated or apparent.

[0062] The separator plate 18 has mutually opposite, outwardly facing surfaces. These surfaces each form an anode side or a cathode side of the separator plate 18, which is why the separator plate 18 accordingly forms a bipolar plate 16. More specifically, a first outwardly facing surface of the separator plate 18 lies opposite and in particular against a porous transport layer (PTL) 20. The PTL 20 comprises or consists of titanium or a titanium alloy. The corresponding surface or side of the separator plate 18 forms an anode side of the bipolar plate 16.

[0063] The corresponding other outward-facing surface of the separator plate 18 of each bipolar plate 16 is opposite and in particular abuts a gas diffusion layer (GDL) 22. The GDL 22 comprises or consists of carbon, and in particular of a carbon fleece. The corresponding surface or side of the separator plate 18 forms a cathode side of the bipolar plate 16.

[0064] A membrane electrode assembly 24, MEA, is arranged between a PTL 20 and adjacent GDL 22. This forms a catalyst support coated with catalyst materials, see a Fig. 1 exemplary marked catalyst layer 26.

[0065] Also shown are cell frame assemblies 31, each comprising two (sub-)cell frames that accommodate a component of the electrochemical system 10 between them. These components can be exposed in a receiving recess 29 of the respective cell frame assemblies, for example, if the component is a PTL or GDL. Other components, and in particular an MEA, can be clamped between opposing (sub-)cell frames and / or squeezed or glued between them. The individual (sub-)cell frames are in Fig. 1 are not marked separately and are explained below.

[0066] During operation of the electrolyzer, water is guided along the anode side of the bipolar plate 16. The water flow direction can be Fig. 1 for example, from vertical top to vertical bottom (or vice versa) or from right to left (or vice versa).

[0067] The water is split into oxygen, electrons, and positively charged hydrogen ions by interacting with an adjacent catalyst layer 26 and applying a voltage from a voltage source 28. The hydrogen ions diffuse to the cathode side, where they combine with the electrons to form hydrogen. To reach the catalyst layer 26, the water must penetrate an adjacent PTL 20.

[0068] Fig. 2 shows a single separator plate 18 as used in the system 10 of Fig. 1 can be used. In Fig. 2, an anode side 17 of the separator plate 18 faces the viewer. The separator plate 18 comprises a plurality of through-openings 30, 32. More precisely, two hydrogen through-openings 32 are provided, each surrounded by a seal 33. The seal 33 prevents a fluid-conducting connection of the hydrogen through-openings 32 to regions of the depicted anode side 17 of the separator plate 18 that lie outside the seal 33 or the region of the anode side 17 enclosed thereby.

[0069] Furthermore, four water passages 30 are provided as an example. These are not sealed against a flow field 38 of the anode side 17 shown and are thus fluidically connected to it. However, the water passages 30 are sealed against the environment of the electrolyzer, as is the flow field 38. For reasons of clarity, such a seal is shown in Fig. 2 is not shown. It can be located, for example, on the separator plate 18 or in an adjacent component.

[0070] A media guide structure 42 consisting of several distribution areas 40 and the flow field 38, each with a channel-web arrangement, is embossed into the anode side 17. The media guide structure 42 comprises a flow area for the water supplied via the water passage openings 30.

[0071] The media guide structure 42 comprises a plurality of channels 34 and webs 36 running between them and separating the channels, in particular spatially and / or structurally. An extension direction and thus also a respective longitudinal axis (not shown separately) of the channels 34 and webs 36 runs in Fig. 2 vertically (except for the distribution areas 40 of the through-openings 32 discussed below). Consequently, the channels 34 and webs 36 each extend between two opposing water through-openings 30.

[0072] The flow region is partially formed by a flow field 38, which is located in an electrochemically active region of the system 10 and in which the guided water participates in the electrochemical reaction of the electrolyzer. Furthermore, the flow region is partially formed by distribution regions 40, in which no electrochemical reaction takes place or, at most, a comparatively significantly reduced electrochemical reaction takes place. These distribution regions 40 are each assigned to one of the through-openings 30, 32 in order to fluidically connect them to the flow field 38, at least in the unsealed cases disclosed here.

[0073] It can be seen that in the example shown, a respective seal 33 does not exactly terminate with an edge region 35 of the associated through-opening 32, although this can also be provided according to embodiments. In the example shown, however, a respective seal 33 crosses the distribution region 40 of the associated through-opening 32. A partial region 41 of the distribution region 40 is thus still fluidically connected to the through-opening 32, but not to the adjacent remaining region of the distribution region 40, let alone the flow field 38. In all embodiments shown here, a respective seal 33 is made of an elastomer material and is injection-molded onto the separator plate 18, more precisely its plate component 19.

[0074] In a manner known per se, the channels 34 and webs 36 form a complementary channel-web arrangement on the cathode side 21 of the separator plate 18 facing away from the viewer. On this cathode side 21, the water passages 30 are fluidically sealed by seals 33, and the hydrogen passages 32 are fluidically connected to the flow area. This is shown in Fig. 3, which shows a view of the cathode side 21 of the separator plate 18 from Fig. 2 shows.

[0075] Alternatively, the flow field 38 can also be smooth and without channels and webs. The channels and webs preferably considered within the scope of this disclosure are therefore located in particular in the distribution areas 40, in particular those channels and webs that interact with a seal 33.

[0076] The Fig. 3 are analogous to the seals 33 of Fig. 2. Optionally, they again cross the distribution areas 40, which connect to the through openings 30 enclosed by the seals 33.

[0077] In the following, partial views of separator plates 18 are shown, wherein the separator plates 18 are designed in particular according to the examples of Fig. 2 and Fig. 3. The seals 33 discussed below can be any seals 33 for sealing any through-openings 30, 32 of a separator plate 18 and in particular any of the seals 33 from the Fig. 2 and Fig. 3.

[0078] Fig. 4 contains a detailed view D of a pair of separator plates 18 with a section axis AA and a sectional view through the separator plates 18 according to this section axis AA. Fig. 4 shows a state in which the separator plates 18 are stacked one above the other and, as further components of the electrochemical system 10 in which they are installed, accommodate two cell frame assemblies 31, for example accommodating a PTL or GDL not shown separately, and an MEA 24 arranged therebetween.

[0079] Referring first to the upper separator plate 18 in the sectional view of Fig. 4 shows that the sectional plane runs through a section of the seal 33, which extends along a region of the separator plate 18 that includes a part of the media guide structure 42. In particular, this can be a section of a distribution region 40, as in Fig. 2 by an exemplary position of an axis B contained in the section plane AA.

[0080] Thus, the area of ​​the separator plate 18, through the channels 34 and webs 36 of the distribution area 40, along which the illustrated section of the seal 33 extends, is topographically uneven and has an irregular height profile. A height axis H, which runs generally orthogonal to a plane of the separator plate 18 (not separately shown), is indicated.

[0081] As mentioned, Fig. 2 an axis B, which in the section plane AA consists of Fig. 4 and in Fig. 4 is also registered. In Fig. 2 it is shown that this axis B extends along an edge region 35 of a through opening 32 which is formed by the Fig. 4 shown seal 33. Thus, the sectional view from Fig. 4 a section of the seal 33 which extends along the through-opening 32. A longitudinal extension direction of the seal 33 or of its outer surface 44 runs in Fig. 4 accordingly along the axis B and thus horizontally from left to right (or vice versa).

[0082] Returning to Fig. 4 shows that the seal 33, on its inner side facing the separator plate 18, completely fills the surface depressions and elevations of the separator plate 18. This occurs because the elastomer seal automatically conforms to the height profile of the separator plate 18 when molded onto the separator plate 18 and completely fills it. The inner side of the seal 33 thus replicates the channels 34 and webs 36 of the separator plate 18. On its outer surface 44 facing away from the separator plate 18, the seal 33 has a topographical design. This topographical design is defined by the geometry of the injection mold. More precisely, it also has a varying height profile H. In the example shown, this variation occurs essentially in the same way as the variation of the separator plate 18 adjacent to the outer surface 44 and along the longitudinal direction or axis B.

[0083] For example, the outer surface 44 of the seal 33 is corrugated in the same way as the side of the upper separator plate 18, to which the seal 33 is integrally formed and along which the seal 33 extends. Where this side of the separator plate 18 has depressions in the form of channels 34 or wave troughs, the outer surface 44 of the seal 33 also has depressions 37 or wave troughs. Where this side of the separator plate 18 has elevations in the form of webs 36 or wave crests, the outer surface 44 also has elevations 39 or wave crests.

[0084] As previously mentioned, the distribution areas 30 of the separator plates 18a, 18b are each complementarily shaped such that the webs 34 formed on a first side or surface of the separator plates 18a, 18b form channels 36 on a second side or surface. Likewise, the channels 36 formed on a first side or surface form webs 34 on a second side or surface. In the context of the previous discussion of Fig. 4, the side of the separator plate 18a, including its webs 34 and channels 36, to which the seal 33 is directly formed was considered, wherein the seal 33 reproduces the web-channel topography of this side on its outer surface 44 in the form of depressions 37 and elevations 39.

[0085] The elevations 37 and depressions 39 are defined, for example, from the perspective of an observer who looks frontally at the corresponding side of the separator plate 18a, i.e. one of Fig. 4 different viewing angles. Likewise, the elevations 37 and depressions 39 can form elevations 37 and depressions 39 with respect to the plane of the separator plate 18a. Likewise, the elevations 37 and depressions 39 can form elevations 37 and depressions 39 in the cross-sectional view of Fig. 4 and with respect to the stacking axis S or height axis H, respectively in the vertically downward direction and / or orthogonal to the axis B, are defined as elevations 37 and depressions 39. The elevations 37 comprise, as their vertices, respective highest local points, and the depressions 39 comprise, as their vertices, respective lowest local points of the respective surfaces. The distances between adjacent highest and lowest local points along the height axis H and in the longitudinal direction along the axis B can have any values ​​disclosed herein.

[0086] The dimensions of the depressions 37 and elevations 39, for example in terms of an amplitude and / or period width of the varying height profile, can be identical when comparing the side of the separator plate 18 facing the seal 33 and the outer surface 44 of the seal 33. However, they can also differ from each other, for example, differ slightly from each other by no more than 20%.

[0087] In Fig. 4 shows that the outer surface 44 of the upper seal 33 rests against the upper cell frame assembly 31. The lower cell frame assembly 31, in contrast, rests against an upper side of the lower separator plate 18b. This lower separator plate 18b also has a seal 33 which is designed analogously to the upper seal 33 and has a correspondingly topographical outer surface 44. This outer surface 44, in turn, rests against an adjacent cell frame assembly 31 in a remaining part of the stack of the electrochemical system 10 (not shown). Thus, the outer surface 44 of the seal 33 of the upper separator plate 18a points in the direction of the adjacent lower separator plate 18b. The seal 33 of this adjacent lower separator plate 18b, and in particular its outer surface 44, in contrast, points away from the upper separator plate 18a.

[0088] The Fig. The separator plates 18a and 18b shown in Figure 4 and adjacent to one another in the stack of the higher-level electrochemical system 10 are arranged relative to one another such that their successive and mutually facing sides along the stack axis S are shaped complementarily to one another. Thus, an inner side of the upper separator plate 18a has elevations or webs 36 in regions where the upper side of the lower separator plate 18b has depressions or channels 34. Likewise, the inner side of the upper separator plate 18a has depressions or channels 34 in regions where the upper side of the lower separator plate 18 has elevations or webs 36.

[0089] The said upper sides and inner sides of the separator plates 18a and 18b are opposite each other when viewed along the stacking axis S and, when clamped, are at least indirectly supported by each other. The elevations and depressions can in turn be defined from the perspective of an observer who, in deviation from the viewing angle of Fig. 4 looks frontally at the corresponding sides or areas.

[0090] When pressed together, compressive forces act between the adjacent separator plates 18a and 18b, with the separator plates 18 being the most rigid component among the numerous components shown. In particular, the seals 33 are supported on a respective adjacent separator plate 18 and, with deformation, on other components arranged between them, such as the cell frame assemblies 31 and the MEA 24, which are deformed during the pressing together.

[0091] The compressive forces run along the stack axis S. It can be seen that in the example from Fig. 4 first sections of the outer surface 44 of the upper seal 33, which in particular each comprise elevations 39, viewed along the stacking axis S, at least indirectly lie opposite and / or face regions of the adjacent separator plate 18 with depressions or channels 34 and are supported on them. Other second sections of the outer surface 44 of the seal 33, which in particular each comprise depressions 37, lie opposite and / or face regions of the adjacent separator plate 18 with elevations or webs 36. The first sections of the outer surface 44 of the seal 33 experience correspondingly lower structural support when compressed compared to the second sections.Figuratively speaking, a support area for the first sections provided by the adjacent separator plate 18 is further away from these first sections than a corresponding support area for the second sections is from these second sections.

[0092] According to the invention, it was recognized that a non-topographical design of the outer surface 44 results in a significantly uneven deformation of a seal 33. This can result in an uneven contact force of the seal 33 against the adjacent cell frame assembly 31. This can be at least partially compensated for with the topographical design of the outer surface 44 disclosed here.

[0093] The latter is confirmed by Fig. 5, which shows a sectional view analogous to Fig. 4 shows the pair of separator plates 18 in a compressed state. It can be seen that the outer surface 44 of the upper seal 33 lies in full contact with the opposing cell frame assemblies 31, even in the areas where the seal 33 faces recesses or channels 34 of the adjacent separator plate 18 or where the seal 33 is supported on them.

[0094] Fig. 6 is a perspective view of the sectional view of the Fig. 4 and Fig. 5. Shown is a partial section of the pair of separator plates 18 and the components 24, 31 enclosed therebetween. The view also shows sections of these components in a transverse direction Q, which is transverse to the axis B of Fig. 4. This transverse direction Q corresponds, as shown in Fig. 2, a direction transverse to an edge region 35 of the through opening 32 sealed by the seal 33.

[0095] It is shown that, viewed along this transverse direction Q, the seal 33 has two adjacent sealing sections 45, each forming a sealing lip. Each of these sealing sections 45 has a topographical outer surface 44 according to the variants discussed above. It has been shown that such a configuration allows an improved sealing effect to be achieved compared to a single large-area sealing section 45. Within the scope of this disclosure, however, it is also possible in principle to provide only a single sealing section 45 with a single outer surface 44.

[0096] The Fig. 7 and Fig. 8 show, as a further embodiment, views analogous to the Fig. 4 and Fig. 5. However, they relate to a case in which an MEA 24 is provided between the separator plates 18 without an additional cell frame assembly 31 enclosing it. Fig. 7 again shows an unstressed state, while Fig. 8 shows a tense state. For further details and achieved effects, please refer to the description of the Fig. 4 and Fig. 5.

Claims

[1] Separator plate (18) for an electrolyzer or other electrochemical system (10), the separator plate (18) comprising at least one plate component (19), with: • a first side (17) and a second side (21) facing away from it, • a flow field (38) on each of the first and second sides (17,21), • several distribution areas (40) with a plurality of channels, wherein two adjacent channels (34) are separated by a web (36), and • a plurality of through openings (30, 32), wherein the through-openings (30, 32) are each connected on one of the first and second sides (17, 21) in a fluid-conducting manner via one of the distribution regions (40) to the flow field (38) of this side and are each fluidically sealed on the corresponding other of the first and second sides (17, 21) by a seal (33) of the separator plate (18) with respect to the flow field (38) of this side (17, 21), wherein at least one of the seals (33) extends at least in sections along an edge region (35) of the through-opening (30, 32) sealed by this seal (33) and has at least one outer surface (44) which, at least in a state uninstalled in the electrochemical system (10), is at least in sections topographical along this longitudinal extent. [2] Separator plate (18) according to claim 1, wherein the seal (33) is made of an elastomeric material. [3] Separator plate (18) according to one of the preceding claims, wherein the topographical configuration of the outer surface (44) comprises having a varying height profile. [4] Separator plate (18) according to one of the preceding claims, wherein the outer surface (44) is shaped similarly to a region of the corresponding one of the first and second sides (17, 21) on which the seal (33) is arranged and along which the outer surface (44) extends. [5] Separator plate (18) according to claim 4, wherein the region comprises a part of one of the distribution regions (40). [6] Separator plate (18) according to one of the preceding claims, wherein the outer surface (44) faces away from the corresponding one of the first and second sides (17, 21) on which the seal (33) is arranged. [7] Separator plate (18) according to claim 3, wherein the height profile varies alternately at least in sections. [8] Separator plate (18) according to one of the preceding claims, wherein the outer surface (44) is corrugated at least in sections. [9] Separator plate (18) according to one of the preceding claims, wherein a height dimension of the seal (33) extends orthogonally to a flat surface plane of the plate component (19). [10] Separator plate (18) according to one of the preceding claims, wherein a height difference between a locally lowest point of the outer surface (44) and an adjacent locally highest point of the outer surface (44) is between 0.01 mm and 1 mm, in particular between 0.2 mm and 0.8 mm. [11] Separator plate (18) according to one of the preceding claims, wherein a distance along the longitudinal extent of the seal between a locally lowest point of the outer surface (44) and a locally highest point of the outer surface (44) adjacent thereto is between 0.1 mm and 2.5 mm, in particular between 1 mm and 2 mm. [12] Separator plate (18) according to one of the preceding claims, wherein the seal (33) has at least two sealing sections (45) projecting relative to the plate component (19), wherein each of the sealing sections (45) has an outer surface (44) which, at least in a state uninstalled in the electrochemical system (10), is topographical in the direction of the longitudinal extent and at least in sections. [13] Electrochemical system (10), in particular electrolyzer, comprising a plurality of separator plates (18) according to one of the preceding claims, wherein the separator plates (18) are arranged in a stack. [14] Electrochemical system (10) according to claim 13, wherein in each pair of adjacent separator plates (18), the at least one seal (33) with a topographical outer surface (44) points from a first separator plate (18) of said pair to a second separator plate (18) of said pair and is supported on said second separator plate (18). [15] Electrochemical system (10) according to claim 14, wherein the topographical outer surface (44) of the at least one seal (33) of the first separator plate (18) is shaped complementarily to an opposite region of the second separator plate (18) and / or facing the outer surface (44), at least in an unstressed state of the stacked separator plates (18). [16] Electrochemical system (10) according to claim 14 or 15, wherein the at least one seal (33) with topographical outer surface (44) of the second separator plate (18) faces away from the first separator plate (18). [17] Electrochemical system (10) according to one of claims 14 to 16, wherein at least one membrane electrode assembly (24) is arranged between the separator plates (18) of each pair of adjacent separator plates (18), the seal (33) of the first separator plate (18) being in contact with the membrane electrode assembly (24). [18] Electrochemical system (10) according to claim 17, wherein a cell frame (27) is arranged between the separator plates (18) of each pair of adjacent separator plates (18) in addition to the membrane electrode unit (24) and on both sides of the membrane electrode unit (24), wherein the seal (33) of the first separator plate (18) bears against one of the cell frames (27).

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