Separator plate for an electrochemical system

Abstract

The invention relates to a separator plate for an electrochemical system. The electrochemical system can in particular be a fuel cell system, an electrochemical compressor, an electrolyzer or a redox flow battery. The invention also discloses an electrochemical system comprising multiple separator plates of this type.

Description

[0001] for an electrochemical m

[0002] The invention relates to a separator plate for an electrochemical system. The electrochemical system can, in particular, be a fuel cell system, an electrochemical compressor, an electrolyzer, or a redox flow battery. An electrochemical system comprising a plurality of such separator plates is also disclosed.

[0003] Known electrochemical systems of this type typically comprise a stack of electrochemical cells, each separated from one another by separator plates. In the context of such stacks, the separator plates are also referred to as bipolar plates. The separator plates can serve, for example, to electrically contact the electrodes of the individual electrochemical cells (e.g., fuel cells) and / or to electrically connect neighboring cells (series connection of the cells). Typically, the separator plates are formed from two individual plates, in particular joined together. The individual plates can be joined together in a materially bonded manner, e.g., by one or more welded joints, in particular by one or more laser-welded joints.

[0004] The separator plates or the individual plates can each have or form structures that are designed, for example, to supply the electrochemical cells arranged between adjacent separator plates with one or more media and / or to transport reaction products away. In particular, these structures can be used to guide a cooling fluid through a space between the individual plates of a separator plate. The structures can, for example, comprise sequences of webs and channels. The media can therefore be fuels (e.g., hydrogen or methanol), reaction gases (e.g., air or oxygen), or coolants. In the context of this disclosure, the terms medium and fluid can be used synonymously.

[0005] Furthermore, the separator plates usually each have at least one through-opening through which the media can be guided to or away from the electrochemical cells or membrane electrode assemblies (MEAs) arranged between adjacent separator plates of the stack. From such a through-opening, a respective fluid is guided by means of the structures described above into a respective first distribution region and from there into a flow field opposite the active region of the cell or MEA. After flowing through the active region, the fluid is fed back to an outlet through-opening via a second distribution region, also called a collection region. An example of this can be found in DE 20 2016 107 302 U1.

[0006] It is known to conduct a first fluid, e.g., a fuel, on a first outer side of the separator plate, i.e., an outer side of a first individual plate, and to conduct a second fluid, e.g., a reaction gas, on a second outer side of the separator plate facing away from the first outer side, i.e., an outer side of a second individual plate. In contrast, a cooling fluid is usually conducted in an interior space defined by the inner sides of the individual plates. The fluid-conducting structures on the respective outer sides of the individual plates form complementarily shaped structures on their inner sides, which conduct the cooling fluid.

[0007] However, it has been shown that the performance of such electrochemical systems can still be optimized. For example, the fluid channels between the through-holes and a flow field still occupy a significant portion of the surface area on the respective sides of a separator plate. This surface area is not available as the active area of ​​the cell and therefore does not directly contribute to its performance.

[0008] An object of the present invention is therefore to improve the performance of an electrochemical system having a plurality of such separator plates.

[0009] This object is achieved by the subject matter of claim 1. Advantageous further developments are specified in the dependent claims as well as in this description and in the figures. Accordingly, a separator plate for an electrochemical system is proposed, comprising a first individual plate and a second individual plate, the inner sides of which face each other, wherein the separator plate has at least one first through-opening for conducting a first fluid through the separator plate and at least one further through-opening for conducting a further fluid through the separator plate, wherein the first individual plate has at least one distribution region and a flow field on its outer side, and the distribution region connects the first through-opening and the flow field in a fluid-conducting manner, wherein the first individual plate further has at least one secondary channel on its outer side,which extends at least in sections along a circumferential section of the further through-opening facing away from the distribution area, wherein the secondary channel opens into a first fluid channel of the flow field and the first through-opening is also fluidly connected to the flow field via the secondary channel.

[0010] According to the invention, the secondary channel utilizes a surface area of ​​the separator plate for supplying fluid to the flow field, which area lies outside conventional distribution areas and also outside the distribution area according to the invention. Consequently, a previously unused fluid supply path is provided for the flow field. According to the invention, it was also recognized that at least sections of the secondary channel can run in areas of the separator plate that can be used as such an additional fluid supply path without significantly impairing other structural features or functions of the separator plate. As explained below, even existing structural features (in particular beads) can be partially utilized for fluid guidance instead, which limits the modification effort compared to existing solutions.

[0011] The at least partial supply of fluid to the flow field through the secondary channel allows the number of channels and / or the area ratio of the distribution area to the total plate area to be reduced compared to existing solutions. This allows for an enlargement of the flow field and thus an increase in the performance of the electrochemical system. A further advantage arises from the fact that the secondary channel can be flowed through at least in sections without fluids accumulating and / or standing still. These could potentially freeze, for example. In existing solutions, however, areas with such stagnant fluid accumulations do exist.

[0012] For example, existing solutions have gaps between adjacent beads, which also fill with fluid from the first through-opening. The fluid can flow in but not out, and therefore remains in the gaps. The secondary channel according to the invention can also include such gaps, but can provide a drainage option via the connection to the flow field, allowing flow through the gaps.

[0013] The through-openings can be configured according to existing solutions. The first and the further through-opening, as well as an optional further through-opening, can be positioned between the distribution area closest thereto and an outer edge of the separator plate. The first and the further through-opening, as well as an optional further through-opening, can follow one another transversely to the main flow axis, preferably at a distance from one another. In a manner known per se, the first and the further through-opening, as well as an optional further through-opening, can be dimensioned differently, in particular with regard to their areas, and / or their area centers of gravity can be positioned at different positions along the main flow axis.

[0014] According to variants described in more detail below, there are three through-openings positioned in the manner described above between the distribution field and the outer edge of the separator plate. The first through-opening and the further through-opening can accommodate the further through-opening between them, e.g., viewed transversely to the main flow axis.

[0015] The separator plate and in particular its first individual plate can have distribution areas on both sides of the flow field, wherein an arrangement of through openings as disclosed here, including preferably a secondary channel as disclosed here, can be provided between each distribution area and an outer edge of the separator plate which is closest thereto, viewed along the main flow axis.

[0016] The further through-opening can, in particular, be a through-opening for a fluid that is guided along an outer side of the second individual plate. The second individual plate can also have at least one distribution region and a flow field on its outer side, and the distribution region connects the further through-opening and the flow field to one another in a fluid-conducting manner.

[0017] The first individual plate can form a cathode plate and / or can carry oxygen or air as a first fluid on its exterior. The second individual plate can form an anode plate and / or can carry hydrogen as a second fluid on its exterior. Alternatively, however, it is also possible for the first individual plate to be designed as an anode plate and / or to carry hydrogen as a first fluid on its exterior. The second individual plate can then be designed as a cathode plate and / or can carry oxygen or air as a second fluid on its exterior.

[0018] The further through-opening can be a through-opening for a fluid that is guided between the facing inner sides of the individual plates. This is typically a cooling fluid, with the facing inner sides defining a cooling fluid distribution structure.

[0019] The secondary channel can be fluidically connected to the first through-opening, for example, with a passage encompassed by or connected to the passage through a sealing bead surrounding the through-opening. In particular, the secondary channel cannot be fluidically connected to the first through-opening via the distribution area. For example, a fluid exiting the first through-opening can branch into the secondary channel and the distribution area.

[0020] In the reverse flow direction, the first through-opening can be fed, in particular, simultaneously from the secondary channel and the distribution area. The volume fraction of the fluid entering or exiting the secondary channel can be smaller than a corresponding volume fraction of the distribution area. In particular, the volume fraction of the secondary channel can be less than 10%, in particular less than 8%, preferably less than 5%, of the volume fraction carried by the distribution area.

[0021] The secondary channel can extend from a location where it is fluidically connected to the first through-opening in a direction away from the distribution area. In particular, the secondary channel can extend toward an outer edge of the separator plate. Alternatively or additionally, it can extend toward a side of the first through-opening facing away from the distribution area.

[0022] The secondary channel can run at least partially at an angle to the main flow axis, in particular substantially transversely thereto. It can extend along an optional further passage opening. In particular, it can run between a circumferential section of the further passage opening facing away from the distribution region and an outer edge of the separator plate closest thereto, as well as in the direction of the further passage opening. This illustrates that the first and the further passage opening are preferably positioned near different longitudinal sides of the separator plate. These longitudinal sides can extend along and in particular parallel to the main flow axis through the flow field.

[0023] The flow field can comprise a plurality of fluid channels in a manner known per se. These can run adjacent to one another, in particular in a straight line and parallel to one another and / or in a similarly corrugated manner. The fluid channels preferably run along the main flow axis of the flow field. This can run parallel to an axis of symmetry and / or the longitudinal axis of the flow field or form such an axis.

[0024] The flow field can be characterized, for example, by all the webs and channels it encompasses being straight and running parallel to each other and parallel to a main flow direction of the cooling fluid through the flow field. Alternatively, the webs and channels could also be wave-shaped and run alongside each other with a similar wave shape and along the main flow axis.

[0025] Additionally or alternatively, the flow field can be characterized by being located within an MEA reinforcement edge and, in particular, being surrounded and / or framed by it at least in sections. However, the flow field itself is preferably not opposite the MEA reinforcement edge, but rather the actually active region of the MEA, in particular in the form of its electrolyte membrane. Reference is made, for example, to DE 20 2020 106 459 U1, and in particular to Figure 3B, which shows an MEA with a reinforcement edge that frames an active region of the MEA. However, the situation can be different with regard to the less deeply shaped region associated with the flow field, in which the MEA reinforcement edge and the GDL overlap.

[0026] According to a further development, the first fluid channel of the flow field is supplied with fluid only from the secondary channel and, in particular, not also from a fluid channel of the distribution area. In the opposite flow direction, this first fluid channel can supply fluid exclusively to the secondary channel and not also to a fluid channel of the distribution area. At the structural level, this means that the first fluid channel of the flow field can be fluidically connected exclusively to the secondary channel or open into it, and not also to a fluid channel of the distribution area. This makes it possible to design the distribution area not for supplying fluid to the first channel and therefore to save space.

[0027] The first fluid channel can, in particular, be an outermost or nearly outermost fluid channel of the flow field. In particular, one embodiment provides that no more than five additional fluid channels of the flow field are positioned between the first fluid channel of the flow field and an outer edge of the separator plate closest thereto, in particular no more than three additional fluid channels. The corresponding nearest outer edge can be a longitudinal side of the separator plate that runs along or parallel to the main flow axis.

[0028] The positioning of the first fluid channel close to the edge is advantageous in that the first through-opening is typically positioned close to the correspondingly opposite outer edge or the correspondingly opposite longitudinal side of the separator plate. The distance between the first fluid channel of the flow field and the first through-opening is correspondingly large. Because this first fluid channel is fed by the secondary channel and does not have to be fed by the distribution area, correspondingly large channel lengths in the distribution area can be eliminated. This allows for significant space savings.

[0029] A further advantage arises from the fact that the fluid connection between the secondary channel and the first fluid channel of the flow field may, under certain circumstances, interrupt the cooling fluid supply to any additional fluid channels located inside the separator plate between the first fluid channel and the outer edge. Therefore, this number should be kept as limited as possible. However, the material of the individual plates allows sufficient heat to be dissipated even in this case. In addition, according to embodiments, it is possible to supply cooling fluid in the area of ​​these additional fluid channels via a perimeter bead.

[0030] A further development provides for the secondary channel to extend along at least one-third of the circumferential length of the additional through-opening. In particular, the secondary channel can completely encircle the additional through-opening. This is particularly advantageous in that existing structural features surrounding the through-opening can be used to define the secondary channel (see below).

[0031] According to one variant, the secondary channel extends at least partially between the peripheral section of the further through-opening facing away from the distribution area and an outer edge of the separator plate closest to the further through-opening. This outer edge can correspond to a transverse side of the separator plate, which runs transversely to the main flow axis. From the perspective of the distribution area, the secondary channel can thus at least partially surround the rear side of the further through-opening. In this case, too, existing structural features can advantageously be used to delimit the secondary channel.

[0032] For example, a further aspect provides that the secondary channel is delimited at least partially and at least partially by a perimeter bead and / or another bead of the separator plate. Any of these beadings can also provide other functions and / or can also be present in existing separator plates that do not, however, have a secondary channel according to the invention.

[0033] At least partial delimitation can be understood as meaning that at least one side and / or at least one edge of the secondary channel is formed or delimited by a corresponding bead. An example of another bead of the separator plate that can provide such an at least partial delimitation of the channel is a sealing bead surrounding at least one of the through openings.

[0034] According to one variant, the secondary channel is bordered at least in sections by two adjacent beads, each of which can form an edge of the secondary channel. This can be, for example, a perimeter bead and a sealing bead, or two sealing beads, each of which surrounds a passage opening.

[0035] The perimeter bead can extend, at least in sections, between the further through-opening and at least one outer edge of the separator plate closest thereto. In particular, it can extend along a peripheral portion of the further through-opening, with this peripheral portion preferably facing away from the distribution area.

[0036] In general, the perimeter bead can run along the circumference and / or the outer edge of the separator plate, in particular in a closed circumferential form.

[0037] Additionally or alternatively, the secondary channel can be defined at least partially and at least partly by at least one weld seam. For example, the secondary channel can run at least partially on the plate surface where a weld seam extends that connects the two individual plates of the separator plate.

[0038] In a further development, the secondary channel further comprises at least one section that extends along a circumferential section of the further through-opening facing the distribution region, wherein at least one fluid channel of the distribution region opens into this section of the secondary channel and / or is fluidically connected thereto. In this case, in addition to opening into a passage through a sealing bead around the first through-opening as explained above, the secondary channel can be fluidically connected to the first through-opening via the distribution region. This variant also enables a reduction in the size of the distribution region, since the channel length required in the distribution region for connecting to the described section of the secondary channel is shorter than the channel length that would be required to feed the first fluid channel of the flow field through the distribution region. The latter occurs instead through the secondary channel.

[0039] As indicated above, a preferred variant provides that the first through-opening is positioned near a first outer edge of the separator plate, and the further through-opening is positioned near a second outer edge of the separator plate, which is opposite the first outer edge. The first and second outer edges can each correspond to a longitudinal side of the type explained above and / or extend along the main flow axis. Accordingly, the first and second outer edges can be opposite each other along an axis running orthogonal to the main flow axis of the flow field.

[0040] According to a further development, the separator plate has a second and third through-opening as additional through-openings, wherein the third through-opening is positioned according to the additional through-opening of the preceding aspect, i.e., near a second outer edge of the separator plate, which is opposite the first outer edge. The second through-opening is preferably arranged between the first and third through-openings, in particular orthogonal to the main flow axis.

[0041] In this context, it can further be provided that the secondary channel extends at least in sections along a circumferential section of both the second and the third through-opening facing away from the distribution area.

[0042] In a further embodiment, the distribution area has at least one, preferably a plurality of, channels, which is / are bounded on both sides by webs. The at least one channel and preferably all or at least the majority of the plurality of channels have a length that is at least 5 times, preferably at least 10 times, in particular at least 20 times as long as the width of a respective channel measured between the height maxima of the webs bounding it. The channels can therefore be elongated fluid-conducting structures.

[0043] When we talk about a flow field here, this can refer to both the actual flow field and an overlap region that closes off the flow field toward the distribution area. Compared to the actual flow field, the cooling fluid channels in the overlap region can be less high, allowing sufficient space for the overlap of the GDL (explained below) and the MEA reinforcement edge.

[0044] The height and the height maxima of the webs can be measured orthogonally to a flat surface plane of the separator plate and in particular of the first individual plates. In a manner known per se, the flat surface plane of a respective individual plate can be defined, for example, by an edge of the individual plate or by those flat areas of the individual plate that are not deformed as a result of a stamping or deep-drawing process to form the web-channel structures or beads described here. On the one hand, the flat surface planes can run in the neutral fibers of the corresponding sections of the plates; on the other hand, it is also possible to consider the surfaces of the relevant sections of the plates as flat surface planes. With the latter approach, however, it must be ensured that when considering distances or the like, the material thickness of only one of two plates under consideration is taken into account.

[0045] The invention also relates to an electrochemical system having a plurality of separator plates according to any aspect described herein.

[0046] The invention is explained below with reference to the accompanying schematic figures. The same reference numerals may be used for similar or equivalent features throughout the figures. Figure 1 shows a perspective view of an electrochemical system with a plurality of stacked separator plates with membrane electrode assemblies arranged between them.

[0047] Figure 2 shows a perspective view of two separator plates of a system similar to Figure 1 with a membrane electrode assembly (MEA) arranged between the separator plates.

[0048] Figure 3 is a schematically simplified representation of a fluid guide within a separator plate according to an example of the prior art.

[0049] Figure 4 is a further schematically simplified representation of the fluid flow within the separator plate according to an example of the prior art.

[0050] Figure 5 is a schematically simplified representation of a fluid guide within a separator plate according to a first embodiment of the invention.

[0051] Figure 6 is a schematically simplified representation of a fluid guide within a separator plate according to a second embodiment of the invention.

[0052] Figure 1 shows an electrochemical system 1 of the type proposed here with a plurality of identical metallic separator plates 2 (or bipolar plates). These are arranged in a stack 6 and stacked along a z-direction 7. The separator plates 2 of the stack 6 are clamped between two end plates 3, 4. The z-direction 7 is also called the stacking direction. In the present example, the system 1 is a fuel cell stack. Two adjacent separator plates 2 of the stack 6 enclose an electrochemical cell between them, which serves, for example, to convert chemical energy into electrical energy. To form the electrochemical cells of the system 1, a membrane electrode assembly (MEA) 10 is arranged between each adjacent separator plates 2 of the stack 6 (see Figure 2 below). The MEAs typically each contain at least one membrane, e.g., an electrolyte membrane.Furthermore, a gas diffusion layer (GDL) can be arranged on one or both surfaces of the MEA.

[0053] In alternative embodiments, system 1 can also be designed as an electrolyzer, compressor, or redox flow battery. Separator plates can also be used in these electrochemical systems. The structure of these separator plates can correspond to the structure of the separator plates 2 explained in more detail here, even if the media flowing onto or through the separator plates in an electrolyzer, an electrochemical compressor, or a redox flow battery can differ from the media used in a fuel cell system.

[0054] The z-axis 7, together with an x-axis 8 and a y-axis 9, spans a right-handed Cartesian coordinate system. The separator plates 2 each define a plate plane, wherein the plate planes of the separator plates 2 are each aligned parallel to the xy-plane and thus perpendicular to the stacking direction (z-axis 7). The end plate 4 has a plurality of media connections 5 through which media can be supplied to the system 1 and through which media can be removed from the system 1. These media that can be supplied to the system 1 and removed from the system 1 can include, for example, fuels such as molecular hydrogen or methanol, reaction gases such as air or oxygen, reaction products such as water vapor or depleted fuels, or a cooling fluid such as water and / or glycol.

[0055] Figure 2 shows a perspective view of two adjacent separator plates 2 or bipolar plates that may be comprised of an electrochemical system of the type of system 1 shown in Figure 1. The separator plates 2 correspond to an example from the prior art. However, the properties and features explained below with reference to them may also apply to the separator plates 2 according to the invention disclosed here or be provided in them, unless otherwise stated or apparent.

[0056] Fig. 2 also shows a known membrane electrode assembly (MEA) 10 arranged between these adjacent separator plates 2, wherein the MEA 10 in Fig. 2 is largely concealed by the separator plate 2 facing the viewer. The separator plate 2 is formed from two materially joined individual plates 2a, 2b, of which in Fig. 2 only the individual plate 2a facing the viewer is visible, which conceals the other individual plate 2b. The individual plates 2a, 2b can each be made of a metal sheet, e.g., a stainless steel sheet. The individual plates 2a, 2b can, for example, be welded to one another, e.g., by laser welding, or can be connected only when the stack is stacked. In particular, the design of fluid-conducting structures on the outer side of the individual plate 2a facing the viewer can differ in Fig. 2 from the structures according to the invention in the further figures below.

[0057] The individual plates 2a, 2b have aligned through-openings, which form through-openings 11a-c of the separator plate 2. When a plurality of separator plates 2 are stacked, the through-openings 11a-c form lines that extend through the stack 6 in the stacking direction 7 (see Figure 1). Typically, each of the lines formed by the through-openings 11a-c is in fluid communication with one of the ports 5 in the end plate 4 of the system 1. For example, a cooling fluid can be introduced into the stack 6 or discharged from the stack 6 via the lines formed by the through-openings 11a. The lines formed by the through-openings 11b, 11c, on the other hand, can be designed to supply the electrochemical cells of the fuel cell stack of the system 1 with fuel and reaction gas, and to discharge the reaction products from the stack 6.

[0058] To seal the through-openings 11a-c from the interior of the stack 6 and from the environment, the individual plate 2a facing the viewer has sealing arrangements in the form of sealing beads 12a-c. These are arranged around the through-openings 11a-c and completely enclose the through-openings 11a-c. The second individual plate 2b also has corresponding sealing beads 12a-c on the rear side of the separator plate 2 facing away from the viewer in Figure 2 for sealing the through-openings 11a-c (not shown). Alternative sealing systems, such as elastomer seals, can also be used. Adjacent to the electrochemically active region 18 of the MEA, the individual plate 2a facing the viewer has, on its outer side facing the viewer, a flow field 17a with structures for guiding a reaction medium along the outer side of the individual plate 2a.These structures are shown in Figure 2 in the form of a plurality of webs and channels extending between the webs and delimited by the webs. On the outer side of the separator plate 2 facing the viewer, the individual plate 2a facing the viewer also has two distribution regions 20a. The distribution regions 20a each comprise structures configured to distribute a medium introduced from a first of the two through-openings 11b into one of the distribution regions 20a by means of the flow field 17a across the active region 18, or to collect or concentrate a medium flowing from the active region 18 or from the flow field 17a to the second of the through-openings 11b. In the latter case, the collecting distribution region 20a can also be referred to as a collection region.The fluid-conducting structures of the distribution areas 20a are also provided in Figure 2 by webs and channels running between the webs and delimited by the webs.

[0059] Without this being specifically shown in Figure 2, a cooling fluid distribution structure 19 formed and / or enclosed between the individual plates 2a, 2b also has distribution regions 20c that overlap with the distribution regions 20a, b of the individual plates 2a, 2b. This cooling fluid distribution structure 19 is fluidically connected to a flow field 17c that overlaps with the flow fields 17a, b of the outer sides of the individual plates 2a, 2b or is enclosed between them, or encompasses this flow field 17c. The web-channel structures on the outer sides of the individual plates 2a, 2b form complementarily shaped web-channel structures on the corresponding inner sides and thus complementarily shaped web-channel structures of the cooling fluid distribution structure 19.

[0060] The two through-openings 11b, or the lines formed by the through-openings 11b through the plate stack of system 1, are each fluidically connected to one another via passages 13b in sealing beads 12b, via the distribution structures of the distribution regions 20, and via the flow field 17a of the individual plate 2a facing the viewer of Figure 2. This individual plate 2a is a second individual plate 2a within the meaning of this disclosure. A fluid guided along the outer side of this individual plate 2a is preferably hydrogen, so that the through-openings 11b are preferably hydrogen through-openings 11b. This results in particular from the smallest cross-section of the hydrogen through-openings 11b compared to the other through-openings 11a, 11c.

[0061] In an analogous manner, the two through-openings 11c or the lines formed by the through-openings 11c through the plate stack of the system 1 are each in fluid communication with one another via corresponding bead feedthroughs 13c, via corresponding distribution structures, and via a corresponding flow field on an outer side of the individual plate 2b facing away from the viewer of Figure 2. This individual plate 2b is a first individual plate 2b within the meaning of this disclosure. A fluid guided along the outer side of this individual plate 2b is preferably air or oxygen, so that the through-openings 11c are preferably air or oxygen through-openings 11c. This results in particular from the largest cross-section of the air or oxygen through-openings 11c compared to the other through-openings 11a, 11b.

[0062] The through-openings 11a, however, or the lines formed by the through-openings 11a through the plate stack of the system 1, are each fluidly connected to one another via a cavity enclosed or surrounded by the individual plates 2a, 2b, which forms the cooling fluid distribution structure 19. This is achieved, for example, again via feedthroughs 13a. This cavity or this cooling fluid distribution structure 19 serves to guide a cooling fluid through the separator plate 2, in particular for cooling the electrochemically active region 18 of the MEA. The through-openings 11a are therefore cooling fluid through-openings, which is particularly evident from their average cross-sectional size compared to the other through-openings 11b, 11c.

[0063] Figure 3 shows a partial area of ​​the separator plate 2 from Figure 2, and more precisely of its first individual plates 2b, which are hidden in Figure 2. This partial area corresponds to an end area comprising three of the through-openings 11a-c. The positioning of these through-openings 11a-c makes it clear that the view is rotated by 90° compared to Figure 2. All of the following Figures 3 to 6 relate to such a partial area. It is understood, however, that the opposite end area, comprising three further through-openings 11a-c, can also be of similar design and have similar fluid guides, as shown in the respective figures. However, the flow directions there are typically reversed (see explanation of Figure 2).

[0064] The view of Figure 3 is particularly schematic in that a fluid guide is shown superimposed by the distribution areas 20a, b. The view therefore corresponds to an orthogonal projection of these fluid guides in a common plane or a view through the separator plate 2. Facts explained below with reference to Figure 3, in particular concerning an arrangement of the through-openings 11a-c, can also be provided in the solution disclosed herein, unless otherwise stated or apparent.

[0065] Shown again are the three through-openings 11a-c and their passages 13a-c through circumferential sealing beads 12a-c (not shown separately). The fluids guided by the through-openings 11a-c and entering the structures of the separator plate 2 are indicated by different types of arrows.

[0066] Furthermore, differently oriented hatching illustrates the extents of the distribution regions 20a, b, which are formed on the outer sides of the individual plates 2a, 2b. The distribution regions 20a, b fluidly connect the illustrated through-openings 11c, 11b to a respective flow field 17a, b. The cooling fluid from the through-opening 11a flows along the inner sides of both of these distribution regions 20a, b toward a flow field 17c for the cooling fluid. This flow field is enclosed between the flow fields 17a, b, or, in other words, by their inner sides.

[0067] It can be seen that the distribution areas 20a, b overlap each other in a cross-hatched area.

[0068] The respective fluids are guided vertically and, for example, rectilinearly along a main flow axis S in the flow fields 17a-c of Figure 3. The flow fields 17a-c have a sequence of elongated fluid channels (not shown separately) along their respective widths running from left to right in Figure 3. The through-openings 11a-c are distributed transversely to the main flow axis S. For example, they, or their respective centroids (not shown separately), are offset from one another along the main flow axis S.

[0069] The through-opening 11c forms a first through-opening within the meaning of this disclosure. The through-opening 11a forms a second through-opening within the meaning of this disclosure. The through-opening 11b forms a third through-opening within the meaning of this disclosure.

[0070] It can be seen that the first through-opening 11c is arranged near a first outer edge 30 of the separator plate 2, wherein this outer edge extends along the main flow axis S and thus corresponds to a longitudinal side of the separator plate 2. Opposite this is a second outer edge 32 of the separator plate 2, particularly when viewed along an axis (not shown) running transversely to the main flow axis S. This second outer edge 32 also therefore corresponds to a longitudinal side of the separator plate 2.

[0071] Also shown is a third outer edge 34 of the separator plate 2, which runs transversely to the main flow axis S and thus corresponds to a transverse side. The fourth outer edge, which is opposite this when viewed along the main flow axis S and forms the further transverse side, is not shown in Figure 3.

[0072] If the fluid exiting the first through-opening 11c is to reach a fluid channel in the flow field 17b near the second outer edge 32 and thus away from the through-opening 11c, a correspondingly long fluid channel must be formed in the distribution area 20b. This comparatively long fluid channel requires a comparatively large amount of space on the outer side of the second individual plate 2b.

[0073] This relationship is further illustrated in Figure 4, which shows a more detailed view of the outside of the second individual plate 2b of the separator plate 2 according to the prior art example. In this case, the individual fluid channels 36b of the distribution region 20b are marked with white arrows, with each fluid channel 36b being delimited by two adjacent webs 38b. Only selected ones of these fluid channels 36b and webs 38b are provided with a corresponding reference symbol in Figure 4. It can be seen that the length of the fluid channels 36b increases when they must supply fluid channels 40b of the flow field 17b at increasing distances from the through-opening 11c. Accordingly, the length of the fluid channels 36b of the distribution region 20b increases continuously from left to right in Figure 4.

[0074] Figure 4 also illustrates further regions 42 of the second individual plate 2b outside the distribution region 20b, which receive fluid from the through-opening 11c. These regions 42, selected ones of which are provided with a corresponding reference symbol, and the fluid received therein are indicated in Figure 4 by a solid dashed line, which can also be referred to as a double-dashed dashed line. Below the first through-opening 11c, this representation changes to a white dashed line for clarity.

[0075] The regions 42 are predominantly delimited by a circumferential perimeter bead 44 and the sealing beads 12a-c surrounding the through-openings 11a-c. The regions 42 extend, in particular, completely around the first and third through-openings 11c, b, along circumferential sections of the further through-opening 11a facing away from the distribution region 20b, as well as in a space between each two of the through-openings 11a, b, c.

[0076] Below the first through-opening 11c is a region 42, shown in white dashed lines, into which the passages 13c open. Furthermore, this region is fluidly connected to the fluid channels 36b of the distribution region 20b. This region 42 extends channel-like along the outer peripheral portion of the first through-opening 11a facing the distribution region 20b and thus at an angle to the respective longitudinal axes of the fluid channels 36b of the distribution region 20b.

[0077] The fluid is distributed from this region 42 into the other regions 42. However, the fluid remains in these regions 42 and does not flow through them, in particular not continuously. Consequently, it does not contribute to the performance of the electrochemical system 1 comprising the separator plate 2. The regions 42 therefore form channels that do not directly contribute to the fluid supply to the flow field 17b. They also have no other separate function, at least not with regard to fluid guidance.

[0078] Figure 5 is a highly simplified schematic view of a first embodiment of the invention. The view corresponds to an analogous partial area of ​​a separator plate 2 as in the case of Figure 3. The separator plate 2 is largely constructed analogously to the examples from Figures 2-4, but in particular with the exception of the fluid guide on the outside of the first individual plates 2b shown below. Due to the overlap, Figure 5 and the subsequent Figure 6 predominantly use the same reference numerals as in the preceding figures.

[0079] Figure 5 is also analogous to Figure 3 in that the fluid guides are shown superimposed by the distribution areas 20a, b. The view therefore again corresponds to an orthogonal projection of these fluid guides into a common plane or a view through the separator plate 2.

[0080] Figure 5 shows that at least the first and third through-openings 11c and 11b are completely surrounded by a secondary channel 50. Analogous to Fig. 4, a section of the secondary channel 50, which runs between the first through-opening 11c and the distribution area 20b, is supplied with fluid from the passages 13c and itself supplies the distribution area 20b.

[0081] The secondary channel 50 runs along the second through-opening 11a transversely to the main flow axis S. The secondary channel 50 extends along a circumferential section of the second through-opening 11a, which faces away from the distribution area 20b. As explained below with reference to Figure 6, the secondary channel 50 can in turn be delimited at least in sections by beads that are to be provided anyway, and in particular can run between them. All sections of the secondary channel 50 shown merge seamlessly into one another in a fluid-conducting manner.

[0082] In contrast to Figure 3, Figure 5 shows only a single hatching, which fills the entire area of ​​the distribution area 20b. However, the flow arrows of the fluid from the third through-opening 11b also clearly indicate the extent of the further distribution area 20a.

[0083] It is shown that a preferably uppermost or outermost fluid channel 36b of the distribution region 20b, viewed along the main flow axis S, opens into the secondary channel 50 by means of a connecting section 51. In particular, the connecting section 51 opens into a section of the secondary channel 50 that runs along the third through-opening 11b and faces the distribution region 20b. As a result, the secondary channel 50 and the first through-opening 11c are also fluidly connected to one another via the distribution region 20b. Optionally, several fluid channels 36b of the distribution region 20b can also open into the secondary channel 50.

[0084] The connecting section 51 can be assigned to the distribution area 20b as a fluid channel extension. Alternatively, it can be understood as a section of the secondary channel 50. Variants without a separate connecting section 51 are also possible, for example, if a fluid channel 36b of the distribution area 20b opens into the secondary channel 50 essentially continuously and without a change of direction.

[0085] Thus, at least a portion of the fluid entering the distribution area 20b from the through-opening 11c via the passages 13c flows from the distribution area 20b back into the secondary channel 50. The fluid can fill all sections of the secondary channel 50 and, in particular, flow through at least some of them. The latter is facilitated by the fact that the secondary channel 50 is fluidly connected to, for example, an outermost fluid channel 40b of the flow field 17b. Thus, at least a portion of the incoming fluid flows out of the secondary channel 50 again and into or through the flow field 17b.

[0086] This fluid channel 40b is fed solely by the secondary channel 50 and is fluidly connected only to the secondary channel 50. However, there is no direct fluid connection between this fluid channel 40b and one of the fluid channels 36b of the distribution area 20b, i.e., no such fluid channel 36b opens into the fluid channel 40b of the flow field 17b fed by the secondary channel 50.

[0087] Finally, Figure 5 also shows that the cooling fluid from the second through-opening 11a is guided only along the inner side of the distribution region 20b of the first individual plates 2b. This is because the connecting section 51 crosses a potential flow path of the cooling fluid in the direction of the third through-opening 11b. Consequently, there is no sufficient flow cross-section in the interior space between the individual plates 2a, 2b for the cooling fluid to reach directly the inner side of the distribution region 20a, which is fluidly connected to the third through-opening 11b, i.e., the coolant distribution region 20c. Instead, the cooling fluid reaches there only via the detour of the inner side of the distribution region 20b. It flows along this inner side into a region in which the distribution regions 20a, b are opposite one another (see the cross-hatched areas in Figure 3).However, it has been shown that a sufficient cooling effect can be achieved even if the cooling fluid flows exclusively along the inside of one of the distribution areas 20a, b.

[0088] Fig. 6 shows a further embodiment of the invention in a view analogous to Fig. 4. Shown is a secondary channel 50 according to the invention, which runs essentially analogously to Fig. 5, but is not additionally fed by a fluid channel 36b of the distribution area 20b.

[0089] It is shown that, near the longitudinal side of the separator plate 2 remote from the first through-opening 11c, the secondary channel 50 extends in the direction of the flow field 17b and opens there into one of the fluid channels 40b of this flow field 17b. Analogous to Figure 5, this fluid channel 40b is directly connected exclusively to the secondary channel 50 and does not open into any of the fluid channels 36b of the distribution area 20b.

[0090] Even if this is not clearly evident from the schematic views of the present figures, this enables, for example, in comparison to Figure 4, a reduced number of fluid channels in the distribution area 20b and / or a reduction in the size of the distribution area 20b along the main flow axis S.

[0091] Figure 6 also schematically indicates a width extension of the flow field 17b through blocks 100, 102 according to another optional embodiment. It is shown that the fluid channel 40b does not necessarily have to be the outermost fluid channel 40b, but that additional fluid channels 40b can also extend between it and a nearest outer edge or a nearest longitudinal side of the separator plate 2. This is illustrated by the smaller block 102 in Figure 6.

[0092] Within the large block 100, reliable cooling can also be achieved by the internal cooling fluid distribution structure 19. In the case of block 102, this is not necessary due to its limited size. However, it would at least also be possible if, in the overlapping regions, at least the flow field on the outer side of the second individual plates 2a were completely connected to the distribution region 20a there and supplied by it, thus preventing a comparable merging of a secondary channel 50 into one of the fluid channels 40a of the flow field 17a.

Claims

Patent claims 1. A separator plate (2) for an electrochemical system (1), comprising a first individual plate and a second individual plate (2a, b), the inner sides of which face each other, wherein the separator plate (2) has at least one first through-opening (11c) for conducting a first fluid through the separator plate (2) and at least one further through-opening (11b) for conducting a further fluid through the separator plate (2), wherein the first individual plate (2b) has at least one distribution region (20b) and one flow field (17b) on its outer side, and the distribution region (20b) connects the first through-opening (11c) and the flow field (17b) to one another in a fluid-conducting manner, wherein the first individual plate (2b) further has at least one secondary channel (50) on its outer side, which extends at least partially along a circumferential section of the further through-opening (11b) facing away from the distribution region (20b),wherein the secondary channel (50) opens into a first fluid channel (40b) of the flow field (17b) and the first through-opening (11c) is also fluidly connected to the flow field (17b) via the secondary channel (50).

2. Separator plate (2) according to claim 1, wherein the first fluid channel (40b) of the flow field (17b) is fed with fluid only from the secondary channel (50) and in particular not also from a fluid channel (36b) of the distribution area (20b).

3. Separator plate (2) according to claim 1 or 2, wherein between the first fluid channel (40b) of the flow field (17b) and an outer edge (32) of the separator plate (2b) closest thereto, no more than five further fluid channels (40b) of the flow field (17b) are positioned, in particular no more than three further fluid channels (40b).

4. Separator plate (2) according to one of the preceding claims, wherein the secondary channel (50) extends along at least one third of the circumferential length of the further through-opening (11b), in particular wherein the secondary channel (50) completely encircles the further through-opening (11b).

5. Separator plate (2) according to one of the preceding claims, wherein the secondary channel (50) is delimited at least in sections and at least in part by a perimeter bead (44) and / or another bead (12a-c) of the separator plate (2), wherein the perimeter bead (44) extends at least in sections between the further through-opening (11a, b) and at least one outer edge of the separator plate (2) closest thereto.

6. Separator plate (2) according to one of the preceding claims, wherein the secondary channel (50) further comprises at least one section which extends along a circumferential section of the further through-opening (11a, b) facing the distribution region (20b), wherein at least one fluid channel (36b) of the distribution region (20b) opens into this section of the secondary channel (50) and / or is fluidly connected thereto.

7. Separator plate (2) according to one of the preceding claims, wherein the first through-opening (11c) is positioned near a first outer edge (30) of the separator plate (2) and the further through-opening (11a, b) is positioned near a second outer edge (32) of the separator plate (2) which is opposite the first outer edge (30).

8. Separator plate (2) according to one of the preceding claims, comprising a second and third through-opening as further through-openings (11a, b), wherein the third through-opening (11b) is positioned according to the further through-opening of claim 7 and the second through-opening (11a) is arranged between the first and third through-openings (11c, b).

9. Separator plate (2) according to claim 8, wherein the secondary channel (50) extends at least in sections along a circumferential section of both the second and the third through-opening (11a, b) facing away from the distribution region (20b).

10. Separator plate (2) according to one of the preceding claims, wherein the distribution area (20b) has at least one channel (36b) which is delimited on both sides by webs (38b), and preferably a plurality of channels (36b) which are each delimited on both sides by webs (38b), wherein the at least one channel (36b) has a length which is at least 5 times, preferably at least 10 times, in particular at least 20 times as long as the width of the channel (36b) measured between the height maxima of the webs (38b) that delimit it.

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