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 typically each have at least one through-opening through which the media and / or reaction products can be conveyed to or from the electrochemical cells arranged between adjacent separator plates of the stack. Likewise, the media is supplied to and removed from the space between the individual plates via through-openings.

[0006] From such a through-opening, a respective fluid is guided by means of the structures described above into a respective first distribution area and from there into an active area of ​​the cell. After flowing through the active area, the fluid is fed back to an outlet through-opening via a second distribution area (also called a collection area). An example of this can be found in DE 20 2016 107 302 U1.

[0007] 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 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). However, a cooling fluid is usually conducted in an interior space defined by the inner sides of the individual plates. The media are typically pumped through the system by means of external pumps.

[0008] The fluid-conducting structures on the respective outer sides of the individual plates form complementary structures on their inner sides, which guide the cooling fluid. However, it has been shown that with previous solutions, the cooling fluid flow is sometimes only possible under increased flow resistance. This places greater demands on the external pumping power. This correspondingly reduces the cooling capacity of the separator plate and can therefore limit the overall performance of the electrochemical system.

[0009] An object of the present invention is therefore to improve the cooling capacity of a separator plate and thus a total performance of an electrochemical system with a plurality of such separator plates and to reduce the flow resistance of the cooling fluid guide.

[0010] 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.

[0011] Accordingly, a separator plate for an electrochemical system is proposed, wherein the separator plate comprises: - a first individual plate and a second individual plate which define an interior of the separator plate with a cooling fluid distribution structure,

[0012] - a first overlap region in which a first section of the cooling fluid distribution structure and a first section of a first fluid distribution region overlap each other, wherein the first fluid distribution region is formed on an outer side of the first individual plate,

[0013] - a second overlap region in which a second section of the cooling fluid distribution structure, a second section of the first fluid distribution region and a section of a second fluid distribution region overlap one another, wherein the second fluid distribution region is formed on an outer side of the second single plate, and wherein: a) the first section of the cooling fluid distribution structure arranged in the first overlap region is the only fluidic connection for guiding the cooling fluid into the second overlap region;or b) the separator plate further comprises a third overlap region in which a third section of the cooling fluid distribution structure and a further section of the second fluid distribution region overlap one another, wherein a volume flow flowing through the first section of the cooling fluid distribution structure can be generated which is at least three times as high, in particular at least five times or at least ten times as high, as a volume flow flowing through the third section of the cooling fluid distribution structure.;

[0014] The first single plate may form a cathode plate and / or may carry oxygen or air as the first fluid.

[0015] The second single plate can form an anode plate and / or can carry hydrogen or other fuel gas as the second fluid.

[0016] In the first overlap region, the second fluid is preferably not conducted. In the third overlap region, the first fluid is preferably not conducted. In the second overlap region, the first to third fluids are preferably conducted in separate flow spaces.

[0017] The first overlap region preferably does not include any portion of the second fluid distribution region. In other words, in the first overlap region, preferably only the first portion of the cooling fluid distribution structure and the first portion of the first fluid distribution region overlap each other. However, there is preferably no overlap between the first portion of the cooling fluid distribution structure and the second fluid distribution region.

[0018] Likewise, the overlap areas can define overlaps that also exist in an orthogonal projection of the respective sections, structures, and features onto a plane surface of the separator plate. An overlap can mean that the corresponding sections, structures, and features are intersected by a common axis that runs perpendicular to the plane surface of the separator plate.

[0019] What both variants a) and b) above have in common is that a deliberately more pronounced (or even exclusive) fluid introduction into the second overlap region occurs through a selected section of the cooling fluid distribution structure. This is also referred to herein as an asymmetric fluid introduction into the second overlap region. According to the invention, it has been observed that this enables a cooling fluid throughput with lower flow resistance compared to previous, more symmetrical fluid introductions, since friction losses for the coolant in the second overlap region are reduced (see below).

[0020] One possible reason for the cooling fluid throughput with lower flow resistance according to the invention is that, with a previous symmetrical (i.e., comparably strong) cooling fluid introduction from multiple sides into the second overlap area, opposing cooling fluid flows of similar strength are generated in the second overlap area. This increases friction losses when these cooling fluid flows collide.

[0021] Further advantages arise from the deliberate reduction or elimination of the third section of the cooling fluid distribution structure, which allows for structural simplifications. Structural features previously used to support the reduced or eliminated cooling fluid introduction path along this third section of the cooling fluid distribution structure can be made smaller or eliminated accordingly. This frees up space within the separator plate, which can be used for other purposes.

[0022] A further development provides that the first section of the cooling fluid distribution structure is proportionately delimited by a step in the second individual plate, which step extends in the direction of the first individual plate. This step can extend along a boundary line between the first and second overlap regions and in particular along a predominant length portion or even along the entire length of this boundary line. The step can promote a change in plane of the cooling fluid guidance, as explained below, and / or delimit associated flow spaces. The step preferably results in the second individual plate running immediately adjacent to the step in the second overlap region in the plane of the second individual plate, while immediately adjacent to the step in the first overlap region it is spaced from this plane of the plane.

[0023] More precisely, a change in the plane of the cooling fluid guidance can occur upon transition from the first to the second overlap region. In particular, a change in flow planes of the cooling fluid distribution structure can take place in such a way that, in the first overlap region, a flow cross-section of the cooling fluid distribution structure extends significantly into a flow space for the cooling fluid spanned by the second individual plate. A section of the first individual plate within the first overlap region, on the other hand, can lie to a greater extent in the plane of the flat surface of the first individual plate and thus, in comparison, provide no significant flow space for the cooling fluid. In the second overlap region, on the other hand, the flow space can also be spanned at least partially by the first individual plate.

[0024] In a manner known per se, a 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 or sections of the individual plate that are not deformed as a result of an embossing or deep-drawing process for forming, in particular, 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 individual plates; on the other hand, it is also possible to consider the surfaces of the relevant sections of the individual 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 individual plates under consideration is taken into account.

[0025] A change of plane of the cooling fluid guidance can also occur when the third overlap region transitions into the second overlap region. In particular, a change of flow planes of the cooling fluid distribution structure can take place in such a way that in the third overlap region a flow cross-section of the cooling fluid distribution structure extends significantly into a flow space for the cooling fluid spanned by the first individual plate. A section of the second individual plate within the third overlap region, on the other hand, can lie predominantly in the plane of the flat surface of the second individual plate and thus, in comparison, provide no significant flow space for the cooling fluid. In the second overlap region, on the other hand, a flow space for the cooling fluid can again be provided at least partially by or in the second individual plate.

[0026] It is understood that any of the above-mentioned flow spaces may be encompassed by the cooling fluid distribution structure and, for example, form fluid-conducting cavities within the cooling fluid distribution structure.

[0027] In a further variant, which builds on the above option b), the third section of the cooling fluid distribution structure is partially delimited by a step in the first individual plate, which extends in the direction of the second individual plate. This step can cause the above-explained change in the plane of the cooling fluid guidance upon transition from the third to the second overlap region. It can delimit a cooling fluid flow space formed primarily in the first individual plate within the third section and / or guide the cooling fluid to the differently located flow plane within the second overlap region. The step can extend along a boundary line between the third and second overlap regions and in particular along a predominant length portion or even along the entire length of this boundary line.

[0028] A further aspect comprising the above option b) provides that a flow cross-section of a transition between the first and second sections of the cooling fluid distribution structure is larger than a (e.g., cumulative) flow cross-section of a transition between the third and second sections of the cooling fluid distribution structure. This promotes a higher fluid throughput through the first section and thus the desired asymmetry of the cooling fluid flow.

[0029] In a further variant comprising the above option b), the first section of the cooling fluid distribution structure, for example on an inner side of the second individual plate, has a first cooling fluid-distributing web-channel structure, and the third section of the cooling fluid distribution structure has a further cooling fluid-distributing web-channel structure, for example on an inner side of the first individual plate, wherein the first and the further cooling fluid-distributing web-channel structure each have a plurality and / or a multiply repeating sequence of webs and of channels formed between each two webs. Any webs and channels disclosed herein can be located at different heights relative to a flat surface plane of an individual plate in which they are formed.

[0030] In the above context, it can further be provided that a flow cross-section of the first section defined by the first fluid-distributing web-channel structure is larger than a flow cross-section of the third section defined by the further fluid-distributing web-channel structure. This can advantageously result in the above-explained enlarged, e.g., cumulative, flow cross-section of a transition between the first and second sections of the cooling fluid distribution structure.

[0031] Additionally or alternatively, the webs and channels of the further fluid-distributing web-channel structure can extend along a respective longitudinal axis in the second section, and at least some of the webs and / or channels, in particular channels or webs, extending from the step delimiting the third and second sections toward the end of the second section facing away from the step delimiting the first and second sections, can be interrupted in at least one section of their respective longitudinal axes. This reduces the spaces provided by the webs and / or channels for the cooling fluid, so that the cooling fluid throughput in the second section of the cooling fluid distribution structure in the flow space spanned by the second individual plate is reduced, and the asymmetry of the fluid guidance is increased.

[0032] One embodiment provides that a fluid distributed by the first fluid distribution region is oxygen or air and a fluid distributed by the second fluid distribution region is hydrogen.

[0033] In a further development, the first fluid distribution area is fluidly connected to a first flow field of the separator plate and the second fluid distribution area is fluidly connected to a second flow field of the separator plate.

[0034] In particular, the first flow field is fluidly connected to a first through-opening formed in the separator plate via the first fluid distribution region. The second flow field is fluidly connected to a second through-opening formed in the separator plate via the second fluid distribution region. The cooling fluid distribution structure is fluidly connected to a third through-opening formed in the separator plate. At the transition from the overlap regions to the flow fields, the cooling distribution structures can have a smaller depth in a short section before reaching the main region of the flow field. This compensates for the greater thickness of the adjacent components.

[0035] Any flow field disclosed here on one of the outer sides of the individual plates can be characterized, for example, in that all of the webs and channels encompassed thereby are rectilinear and run parallel to one another and parallel to a main flow direction of the flow field. Alternatively, the webs and channels of the flow field could also be wave-shaped and run alongside one another with a similar wave shape and along a main flow direction of the flow field. The wave shape can oscillate uniformly around the main flow axis and / or the main flow axis can define a central axis of the wave shape around which the wave-like oscillation occurs.

[0036] Additionally or alternatively, a flow field on one of the outer sides of the individual plates 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 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 formed region associated with the flow field, in which the MEA reinforcement edge and the GDL overlap.

[0037] According to an optional aspect, the cooling fluid guided by the first section of the cooling fluid distribution structure enters the second overlap region via a web-channel structure on an inner side of the second individual plate, which forms a complementarily shaped web-channel structure of the first fluid distribution region. This occurs, in particular, exclusively via the inner web-channel structure from the inner side of the second individual plate into the second overlap region. This can be accompanied by the above-explained change in the plane of the cooling fluid guidance upon transition from the first to the second overlap region.

[0038] In a further embodiment, the cooling fluid guided by the third section of the cooling fluid distribution structure enters the second overlap region via a web-channel structure on an inner side of the first individual plate, which forms a complementarily shaped web-channel structure of the second fluid distribution region, and in particular enters the second overlap region exclusively via the inner side web-channel structure from the inner side of the first individual plate.

[0039] In particular, the cooling fluid can enter the second overlap region from the first and / or the third overlap region with a change in a flow direction, wherein the change in the flow direction comprises an angle of more than 90°, preferably more than 110° and in particular more than 135°.

[0040] A further variant provides that within the first section of the cooling fluid distribution structure, an inner side of the second individual plate is formed differently from the web-channel structure of the inner side of the first individual plate. In particular, within the first section, on the inner side of the second individual plate:

[0041] - fewer webs and channels than within the web-channel structure of the inside of the first single plate; and / or

[0042] - there are no or at least fewer webs or channels leading into the second overlapping area and / or leading into a possible third through-opening of the type described above; and / or

[0043] - Distances between webs and channel widths must be larger than within the web-channel structure of the inside of the first individual plate.

[0044] The distances and channel widths can be measured in or parallel to the plane of the second single plate. Any webs and channels disclosed herein can be elongated, so that a respective width dimension runs transversely to their longitudinal extent.

[0045] The above variants each promote a fluid throughput with low flow resistance through the first section, e.g. because there are fewer flow obstacles on the inside of the second individual plate.

[0046] Also disclosed is an electrochemical system having a plurality of separator plates according to any aspect disclosed herein and electrochemical cells disposed between these separator plates.

[0047] 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 according to an embodiment of this disclosure, comprising a plurality of stacked separator plates with membrane electrode assemblies arranged therebetween.

[0048] 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, wherein the separator plates are designed according to an example of the prior art.

[0049] Figure 3 shows a schematically highly simplified representation of a coolant guide within a section of a separator plate which is designed according to a first embodiment of this disclosure.

[0050] Figure 4 shows a perspective partial view of the separator plate of the first embodiment with a view of a fluid distribution area of ​​a second individual plate, in particular anode plate, of the separator plate.

[0051] Figure 5 shows a schematic, simplified view of the fluid guide in a fluid distribution area of ​​the separator plate according to the invention.

[0052] Figure 6 shows a perspective partial view of a separator plate according to a further embodiment with a view of a fluid distribution region of a first individual plate, in particular cathode plate, of the separator plate.

[0053] Figure 7 shows a schematic, simplified view of the fluid guide in a fluid distribution area of ​​the separator plate according to the invention.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] Fig. 2 also shows a known membrane electrode assembly (MEA) 10 arranged between these adjacent separator plates 2, wherein the MEA 10 in Figure 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 Figure 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 deviate from the inventive structures of the further Figures 3 to 7 below.

[0059] 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.

[0060] 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.

[0061] Adjacent to the electrochemically active region 18 of the MEA, the individual plate 2a facing the viewer in Figure 2 has, on its outer side facing the viewer in Figure 2, a flow field 17a with structures for guiding a reaction medium along the outer side of the individual plate 2a. These structures are designed in Figure 2 in the form of a plurality of webs and channels running between the webs and delimited by the webs. On the outer side of the separator plate 2 facing the viewer in Figure 2, the individual plate 2a facing the viewer also has two distribution regions 20. The distribution regions 20 each comprise structures which are designed to distribute or direct a medium introduced from a first of the two through-openings 11b into one of the distribution regions 20 over the active region 18 by means of the flow field 17.to collect or concentrate a medium flowing from the active region 18 to the second of the through openings 11b. In the latter case, the collecting distribution region 20 can also be referred to as a collecting region.

[0062] The fluid-carrying structures of the distribution areas 20 are also provided in Figure 2 by webs and channels running between the webs and delimited by the webs.

[0063] 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 that overlap with the distribution regions 20 of the individual plates 2a, 2b. This cooling fluid distribution structure 19 is fluidically connected to or encompasses a flow field, wherein this flow field overlaps with the flow fields 17a, 17b of the outer sides of the individual plates 2a, 2b or is enclosed between them. 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] In the following, fluid guides in a separator plate 2 according to one embodiment of the invention are explained with reference to Figures 3 to 7. The separator plate 2 is designed in principle analogous to Figures 1 and 2 and additionally has the features and special features explained below with regard to the fluid guides. In each case, Figures 3 to 7 approximately depict a region of a separator plate 2 outlined in dashed lines in Figure 2, although reference is also partially made to the outer side of the first individual plate 2b facing away from the viewer or to the internal cooling fluid structure.

[0068] Furthermore, Figures 3 to 7 explained below consider distribution regions 20 of the individual plates 2a, 2b and the cooling fluid distribution structure 19, each of which conducts a fluid from one of the through-openings 11a-c to a flow field 17, 17a-b. However, the explanations also apply to the collecting distribution regions 20 (or collection regions) of the separator plate 2 at the corresponding other end of the flow fields 17, 17a-b. In particular, in the case of a reversed fluid flow direction, the fluid-distributing distribution regions 20 considered below can also function as collection regions.

[0069] Figure 3 shows a highly simplified schematic representation of a coolant guide within a separator plate 2 according to the invention. More precisely, an extension of the cooling fluid distribution structure 19 is schematically shown in an area analogous to the dashed area in Fig. 2. The illustrated area corresponds to a distribution area of ​​the cooling fluid distribution structure 19. It is understood that the cooling fluid distribution structure 19 cannot be seen in the manner shown due to its position between the individual plates 2a, 2b when the separator plate 2 is joined together.

[0070] The perspective of Figure 3 is rotated relative to Figure 2, as can be seen from the schematically illustrated positions of the through-openings 11a-c. Furthermore, the arrangement of these through-openings 11a-c illustrates that the cooling fluid distribution structure 19 is oriented as if a not-shown outer side of the first individual plate 2b from Figure 2 were facing the viewer. The through-openings 11a-c again have the size ratios explained above.

[0071] The cooling fluid distribution structure 19 is defined by the mutually facing inner sides of the individual plates 2a, 2b. More precisely, opposing regions of these inner sides are spaced apart from one another to varying degrees, forming fluid-receiving spaces (i.e., flow spaces) of the cooling fluid distribution structure 19. The cooling fluid distribution structure 19 also has web-channel structures (not shown), which form complementarily shaped web-channel structures on the outer sides of the individual plates 2a, 2b, as explained above with reference to Figure 2.

[0072] The cooling fluid distribution structure 19 has three sections A, B, and C, each of which is essentially triangular in shape. The first section A and the third section C are each fluidly connected to the cooling fluid passage 11a. The fluid-connecting passages through the sealing elements surrounding the cooling fluid passage 11a, as explained above, are not shown separately in Figure 3, but are nevertheless present. Two arrows 1A and 1C each represent a fluid inflow from the cooling fluid passage 11a into the first and third sections A and C. The size of the arrows illustrates the relative sizes of these flows. It is thus evident that the fluid inflow 1A into the first section A is significantly larger (for example, at least three times, at least five times, or at least ten times as large) than the fluid inflow 1C into the third section C.It goes without saying that a reverse flow direction is also possible.

[0073] The first section A of the cooling fluid distribution structure 19 runs in a first overlap region 15 of the separator plate 2. In this region, the first section A overlaps with a first section of a distribution region 20 of the first individual plate 2b, which is also referred to below as the first fluid distribution region 21 (not shown in Fig. 3). Consequently, the section A is delimited by a section of the inner side of the first individual plate 2b, which faces away from this fluid distribution region 21 or forms its inner side, as well as by an opposite inner side of the second individual plate 2a. The correspondingly delimiting section of the first individual plate 2b runs in sections in the plane of the planar surface of this individual plate 2b.The correspondingly delimiting section 30 of the second individual plate 2a (see Figure 4 discussed below), however, is predominantly shaped opposite the plane of the flat surface of this individual plate 2a and in a direction away from the first individual plate 2b. As a result, it essentially forms a flow space of the first section A of the cooling fluid distribution structure 19.

[0074] The second section B of the cooling fluid distribution structure 19 extends in a second overlap region 22, in which the first fluid distribution region 21 and a second fluid distribution region 23 (not shown in Fig. 3) overlap, which is a distribution region 20 of the second individual plate 2a. The fluid distribution regions 21, 23 are formed on the outer sides of the respective individual plates 2a, 2b (see Figs. 4 and 6). In this second overlap region 22, sections of the inner sides of the individual plates 2a, 2b lie opposite one another, having web-channel structures that are complementary to the web-channel structures of the respective fluid distribution regions 21, 23. The web-channel structures of these opposing inner sides extend in intersecting directions, which means an increased flow resistance for the cooling fluid.

[0075] The third section C of the cooling fluid distribution structure 19 extends in a third overlap region 24, in which a section of the second fluid distribution region 23 and a section 48 (see Figure 6 discussed below) of an inner side of the first individual plate 2b overlap each other. It should be noted again that this third overlap region 24, and consequently also the third section C of the cooling fluid distribution structure 19, are merely optional. The structural configurations of the first to third sections AC and the first to third overlap regions 15, 22, 24 are explained in more detail below with reference to Figures 4-7.

[0076] Figure 4 shows a section of the bipolar plate 2 with a view of the outer side of the second individual plate 2a, in particular the anode plate, in the area outlined in dashed lines in Figure 2. The viewing angle is rotated compared to Figure 3, as can be seen from the indicated position of the through-opening 11b in Figure 4. Only a cut-off part of the flow field 17a is shown. In this, a fluid is guided from the through-opening 11b via the second fluid distribution region 23 and through a web-channel structure 40 on the outer side of the second individual plate 2a. By way of example only, the web-channel structure 40 has a plurality of outwardly projecting webs 27 and channels 29 enclosed therebetween, selected ones of which are provided with a corresponding reference symbol.As shown, the webs 27 are optionally interrupted in sections along their longitudinal extent, but can also extend continuously in the direction of the flow field 17. With the exception of the webs 27, the second fluid distribution area 23 extends in a plane plane Ea of the second individual plate 2a.

[0077] The second fluid distribution region 23 is delimited by an elongated step 32, which is directed away from the opposite first individual plate 2b and extends in the direction of a side of the flow field 17b remote from the through-opening 11b. Adjoining the step 32, in the direction away from the flow field 17b, is a section 42 of the second individual plate 2a that is raised relative to the plane Ea of the second individual plate 2a and that significantly delimits, or in other words, spans, a flow space of the first section A of the cooling fluid distribution structure 19. The raised section 42 forms the aforementioned section 30 of the second individual plate 2a, which partially delimits the first section A of the cooling fluid distribution structure 19.

[0078] An optionally shown plurality of stiffening or supporting beads 44 in this section 42 can also be omitted. In any case, the stiffening or supporting beads 44 form fewer and more widely spaced webs or wider channels than those present on the opposite inner side of the first individual plate 2b. Furthermore, the stiffening or supporting beads 44 do not open into the second overlap region 22 or into the second through-opening 11a. Thus, the second fluid is not guided in the first overlap region 15.

[0079] The step 32 forms a complementarily shaped inner step 33 within the first section A of the cooling fluid distribution structure 19, which extends toward the first individual plate 2b. This inner step 33 consequently promotes the above-described level change when the cooling fluid passes from the first overlap region 15 into the second overlap region 22. The second fluid is not guided in the first overlap region 15.

[0080] Since the cooling fluid is primarily guided within the flow space of the raised section 42, the webs 27 of the second fluid distribution area 23 do not necessarily have to form significant flow paths for the cooling fluid. Therefore, they can be kept correspondingly narrow, for example, allowing the second fluid distribution area 23 to be kept small overall.

[0081] Figure 5 shows a highly simplified schematic representation of a fluid flow, in particular the guidance of hydrogen within a separator plate 2 according to the invention. In Figure 5, the viewing angle, as evident from the position of the through-opening 11b, is rotated relative to the second individual plate 2a shown in Figure 4 and essentially corresponds to that of Figure 3. Figure 5 reflects the extent of the second fluid distribution region 23 on the outside of the second individual plate 2a, with a direction of the fluid flows within the second fluid distribution region 23 indicated by arrows. A position of the flow field 17a on the outside of the second individual plate 2a is also shown. The section 48 shown at the top right in Figure 5 is part of a third section C of the separator plate 2.

[0082] Figure 6 shows a section of the outer side of the bipolar plate 2 with a view of the first individual plate 2b, in particular the cathode plate, in the area outlined in dashed lines in Figure 2 according to one embodiment. This can be combined with the embodiment of Figure 4. One viewing angle is rotated, in particular, compared to Figure 3, as can be seen from the indicated position of the through-opening 11c in Figure 6. Only a cut-off part of the flow field 17b is shown. In the section shown, a fluid is guided from the through-opening 11c via the first fluid distribution region 21 and through a web-channel structure 46 on the outer side of the first individual plate 2b. By way of example only, the web-channel structure 46 has a plurality of outwardly projecting webs 27 and channels 29 enclosed therebetween, selected ones of which are provided with a corresponding reference symbol.The webs 27, as shown, have an optionally curved central region, but can also extend essentially without curvature in the direction of the flow field 17b. With the exception of the webs 27, the first fluid distribution region 21 extends in a plane Eb of the first individual plate 2b.

[0083] Figure 6 also shows the raised section 42 of the second individual plate 2a and the first section A of the cooling fluid distribution structure 19 formed therefrom (see Figure 4). A portion of the second fluid distribution region 23 is also visible.

[0084] Figure 6 shows an embodiment in which the first individual plate 2b is designed such that the third overlap region 24 and thus the third section C of the cooling fluid distribution structure 19 are omitted. However, if this overlap region 24 or this third section C is to be provided, as shown in Figure 3, a section 48 that is raised relative to the flat surface plane of the first individual plate 2a can be provided in the area indicated by dashed lines in Figure 6, analogous to the raised section 42 of the second individual plate 2b from Figure 4. By means of this raised section 48, a flow space for the cooling fluid can be provided in the third section C shown in Figure 3.

[0085] Figure 5 indicates a possible extension of this optional raised section 48, which lies opposite an inner side of the second individual plate 2a. In this case, too, the raised section 48 is delimited by an inner step 50. This extends toward the opposite second individual plate 2a and promotes the above-described level change when the cooling fluid passes from the optional third overlap region 24 into the second overlap region 22.

[0086] Figure 7 shows a highly simplified schematic representation of a fluid flow, in particular the guidance of oxygen, within a separator plate 2 according to the invention. Figure 7 is a simplified schematic view, wherein the viewing angle, as can be seen from the position of the through-opening 11c, is rotated compared to Figure 6 and essentially corresponds to that of Figure 3. Figure 7 reflects the extent of the first fluid distribution region 21 on the outside of the first individual plate 2b, wherein a direction of the fluid flows within the first fluid distribution region 21 is indicated by arrows. Furthermore, an extent of the raised section 42 and the step 33 delimiting this section 42 is shown.

[0087] Returning to Figure 3, a fluid guide within the cooling fluid distribution structure 19 is explained, which results from the structural features of Figures 4-7 explained above. Steps 33 and 50 are also shown in Figure 3.

[0088] As explained, the comparatively largest fluid inflow 1A occurs in the first section A. In contrast, a smaller fluid inflow 1C occurs in the third section C, if present. From the first section A, the cooling fluid flows along the step 32 and crosses it into the second overlap region 22, as indicated by curved arrows. In doing so, it undergoes the change of plane described above. In addition, the cooling fluid flow undergoes a change of direction, with an indicated angle W of the change of direction being more than 90°. Such an angular size advantageously reduces the increase in flow resistance for the cooling fluid associated with the change of direction.

[0089] This change of direction is determined by the orientation of the web-channel structure 46 of the first fluid distribution region 21 (or by the complementarily formed web-channel structure on the inner side of the first individual plate 2b facing away from the first fluid distribution region 21).

[0090] From the optional third section C, the cooling fluid flows along the step 50 and crosses it into the second overlap region 22, as also indicated by curved arrows. In doing so, it undergoes the above-described change of plane and a similar change in flow direction of more than 90°. The fluid flows 2A, 2C flow through the second overlap region 22 toward an (internal) flow field 17 of the cooling fluid distribution structure 19, crossing and mixing several times.

[0091] It should be noted that a cumulative flow cross-section, as provided by the web-channel structures on the inner sides of the two individual plates 2a, 2b, is preferably larger at the transition from the first to the second overlap region 15, 22 than a cumulative flow cross-section at the transition from the third to the second overlap region 24, 22. From the above, it is clear that the cooling fluid is deliberately guided asymmetrically within the cooling fluid distribution structure 19, in such a way that the cooling fluid flows predominantly or optionally exclusively via the first overlap region 15 into the second overlap region 22. This is accompanied by the advantage explained above, according to which friction losses of the fluid flows 2A, 2C intersecting in the second overlap region are reduced, specifically in favor of the overweighted fluid flow 2A.Consequently, the flow resistance of the cooling fluid distribution structure 19 can be reduced overall, which enables operation of the electrochemical system at a higher power.

Claims

Patent claims 1. Separator plate (2) for an electrochemical system (1), wherein the separator plate (2) comprises: - a first individual plate (2b) and a second individual plate (2a) which define an interior of the separator plate (2) with a cooling fluid distribution structure (19), - a first overlap region (15) in which a first section (A) of the cooling fluid distribution structure (19) and a first section of a first fluid distribution region (21) overlap each other, wherein the first fluid distribution region (21) is formed on an outer side of the first individual plate (2b), - a second overlap region (22) in which a second section (B) of the cooling fluid distribution structure (19), a second section of the first fluid distribution region (21) and a section of a second fluid distribution region (23) overlap one another, wherein the second fluid distribution region (23) is formed on an outer side of the second individual plate (2a), and wherein: a) the first section (A) of the cooling fluid distribution structure (19) arranged in the first overlap region (15) is the only fluidic connection for guiding the cooling fluid into the second overlap region (22);or b) the separator plate (2) further comprises a third overlap region (24) in which a third section (C) of the cooling fluid distribution structure (19) and a further section of the second fluid distribution region (23) overlap one another, wherein a volume flow (1A) flowing through the first section (A) of the cooling fluid distribution structure (19) can be generated which is at least three times as high as a volume flow (1C) flowing through the third section (C) of the cooling fluid distribution structure (19).

2. Separator plate (2) according to claim 1, characterized in that the first section (A) of the cooling fluid distribution structure (19) is partially delimited by a step (33) in the second individual plate (2a) which extends in the direction of the first individual plate (2b).

3. Separator plate (2) according to claim 1 or 2, each with option b) of claim 1, characterized in that the third section (C) of the cooling fluid distribution structure (19) is partially delimited by a step (50) in the first individual plate (2b) which extends in the direction of the second individual plate (2a).

4. Separator plate (2) according to one of the preceding claims with option b) of claim 1, characterized in that a flow cross-section of a transition between the first and second section (A, B) of the cooling fluid distribution structure (19) is larger than a flow cross-section of a transition between the third and second section (C, B) of the cooling fluid distribution structure.

5. Separator plate (2) according to one of the preceding claims, characterized in that a fluid distributed by the first fluid distribution region (21) is oxygen or air and a fluid distributed by the second fluid distribution region (23) is hydrogen.

6. Separator plate (2) according to one of the preceding claims, characterized in that the first fluid distribution region (21) is fluidly connected to a first flow field (17b) of the separator plate (2) and the second fluid distribution region (23) is fluidly connected to a second flow field (17a) of the separator plate (2); and in particular wherein the first flow field (17) is fluidly connected via the first fluid distribution region (21) to a first through-opening (11c) formed in the separator plate (2), the second flow field (17a) is fluidly connected via the second fluid distribution region (23) to a second through-opening (11b) formed in the separator plate (2), and the cooling fluid distribution structure (19) is fluidly connected to a third through-opening (11a) formed in the separator plate (2).

7. Separator plate (2) according to one of the preceding claims, characterized in that the cooling fluid guided by the first section (A) of the cooling fluid distribution structure (19) enters the second overlap region (22) via a web-channel structure on an inner side of the first individual plate (2b), which forms a complementarily shaped web-channel structure (46) of the first fluid distribution region (21), and in particular enters the second overlap region exclusively via this inner web-channel structure from the inner side of the first individual plate (2b).

8. Separator plate (2) according to one of the preceding claims, characterized in that the cooling fluid guided by the third section (C) of the cooling fluid distribution structure (19) enters the second overlap region (22) via a web-channel structure on an inner side of the second individual plate (2a), which forms a complementarily shaped web-channel structure (40) of the second fluid distribution region (23), and in particular enters the second overlap region (22) exclusively via this inner side web-channel structure from the inner side of the second individual plate (2a).

9. Separator plate (2) according to claim 7 and / or 8, characterized in that the cooling fluid from the first and / or the third overlap region (15, 24) enters the second overlap region (22) with a change in a flow direction, wherein the change in the flow direction comprises an angle of more than 90°, preferably more than 110° and in particular more than 135°.

10. Separator plate (2) according to claim 7, characterized in that within the first section (A) of the cooling fluid distribution structure (19) an inner side of the second individual plate (2a) is formed differently from the web-channel structure of the inner side of the first individual plate (2b), in particular wherein within the first section (A) on the inner side of the second individual plate (2a): - fewer webs and channels than are present within the web-channel structure of the inside of the first individual plate (2b); and / or - no or at least fewer webs or channels are present which open into the second overlapping region (22) and / or which, in a design of the separator plate (2) according to claim 6, open into the third through-opening (11a); and / or - Distances between webs and channel widths are larger than within the web-channel structure of the inside of the first individual plate (2b).

11. Separator plate (2) according to one of the preceding claims, characterized in that the first individual plate (2a) carries oxygen or air as a first fluid and the second individual plate (2b) carries hydrogen or another fuel gas as a second fluid, wherein the second fluid is not carried in the first overlap region (22).

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