WO2024256512A1 - Separator plate for an electrochemical system - Google Patents

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

für ein elektrochemisches

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for an electrochemical

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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 with a plurality of such separator plates is also disclosed.

Known electrochemical systems of the type mentioned normally comprise a stack of electrochemical cells, each of which is 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 adjacent cells (series connection of the cells). The separator plates are typically 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.

The separator plates or the individual plates can each have or form structures which are designed, for example, to supply the electrochemical cells arranged between adjacent separator plates with one or more media and/or to transport away reaction products. In particular, these structures can be used to guide a cooling fluid through a gap 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.

Furthermore, the separator plates usually each have at least one through-opening through which the media and/or the reaction products are guided to the electrochemical cells arranged between adjacent separator plates of the stack or are led away from them. The media supply and removal in the space between the individual plates also takes place via through openings.

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 Ul.

It is known to guide 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 guide a second fluid (e.g. a reaction gas) on a second outer side of the separator plate facing away from it (i.e. an outer side of a second individual plate). In contrast, a cooling fluid is usually guided in an interior space delimited by the inner sides of the individual plates. The media are usually guided through the system using external pumping services.

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 guidance is sometimes only possible under increased flow resistance. This places higher demands on the external pumping power. This reduces the cooling capacity of the separator plate accordingly and can consequently lead to limitations in the overall performance of the electrochemical system.

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.

This object is solved 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, wherein the separator plate comprises: - a first single plate and a second single plate defining an interior of the separator plate with a cooling fluid distribution structure,

- a first overlap region in which a first portion of the cooling fluid distribution structure and a first portion of a first fluid distribution region overlap each other, wherein the first fluid distribution region is formed on an outer side of the first single plate,

- 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 individual 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 has 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.

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

The second single plate can form an anode plate and/or can carry hydrogen or other fuel gas as a second fluid.

In the first overlap region, the second fluid is preferably not guided. In the third overlap region, the first fluid is preferably not guided. In the second overlap region, the first to third fluids are preferably guided in flow spaces separate from one another.

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 section of the first fluid distribution region. Preferably, however, there is also no overlap between the first section of the cooling fluid distribution structure and the second fluid distribution region.

The overlapping areas can also define overlaps that also exist in an orthogonal projection of the respective sections, structures and features into a plane of the separator plate. An overlap can mean that the corresponding sections, structures and features are cut by a common axis that runs perpendicular to the plane of the separator plate.

Both variants a) or b) above have in common that a deliberately more pronounced (or even exclusive) fluid introduction into the second overlap region takes place through a selected section of the cooling fluid distribution structure. This is also referred to herein as an asymmetrical fluid introduction into the second overlap region. According to the invention, it was 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).

One possible reason for the cooling fluid throughput according to the invention with lower flow resistance is that with a previous symmetrical (i.e. comparably strong) cooling fluid introduction from several 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 meet.

Further advantages arise in that structural simplifications are possible due to the deliberate reduction or elimination of the third section of the cooling fluid distribution structure. Structural features previously used to support the reduced or eliminated additional cooling fluid introduction path along this third section of the cooling fluid distribution structure can be made smaller or can also be eliminated. This frees up installation space within the separator plate, which can be used for other purposes.

A further development provides that the first section of the cooling fluid distribution structure is limited proportionately by a step in the second individual plate, which extends in the direction of the first individual plate. This step can extend along a boundary line between the first and second overlapping areas and in particular along a predominant length portion or also along the entire length of this boundary line. The step can promote a change of level of the cooling fluid guide as explained below and/or delimit associated flow spaces. The step preferably leads to the second individual plate running immediately adjacent to the step in the second overlapping area in the plane of the second individual plate, while immediately adjacent to the step in the first overlapping area it is spaced from this plane.

More precisely, a change in the plane of the cooling fluid guide can occur when the first to the second overlap region passes over. 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 in 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 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.

In a manner known per se, a plane surface 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 to form, in particular, the web-channel structures or beads described here. On the one hand, the plane 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 plane 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 considered is taken into account.

A change in the level of the cooling fluid guidance can also occur when the third overlap area passes into the second overlap area. In particular, a change in flow levels of the cooling fluid distribution structure can take place in such a way that in the third overlap area a flow cross section of the cooling fluid distribution structure is located significantly in a flow space for the cooling fluid spanned by the first individual plate. extends. A section of the second individual plate within the third overlap region can, however, lie predominantly in the plane of the second individual plate and thus, in comparison, provide no significant flow space for the cooling fluid. In the second overlap region, however, a flow space for the cooling fluid can again be provided at least partially by or in the second individual plate.

It is understood that any of the above-mentioned flow spaces can be included in the cooling fluid distribution structure and, for example, form fluid-conducting cavities within the cooling fluid distribution structure.

In a further variant, which builds on the above option b), the third section of the cooling fluid distribution structure is proportionately limited 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 level of the cooling fluid guide when passing from the third to the second overlap area. It can limit a cooling fluid flow space formed within the third section primarily in the first individual plate and/or guide the cooling fluid to the differently located flow level within the second overlap area. The step can extend along a boundary line between the third and second overlap areas and in particular along a predominant length portion or also along the entire length of this boundary line.

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 guide.

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 multiple repeating sequence of webs and of channels formed between each two webs. Any webs and channels disclosed herein can be based on different heights relative to a flat surface plane of an individual plate in which they are formed.

In the above context, it can also 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 enlarged, e.g. cumulative, flow cross-section of a transition between the first and second sections of the cooling fluid distribution structure explained above.

Additionally or alternatively, the webs and channels of the further fluid-distributing web-channel structure in the second section can extend along a respective longitudinal axis and at least some of the webs and/or channels, in particular channels or webs, running from the step delimiting the third and second sections in the direction of 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.

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.

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

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

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 included here are straight 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 with a similar wave shape next to one another and along a main flow direction of the flow field. The wave shape can oscillate evenly around the main flow axis and/or the main flow axis can define a central axis of the wave shape around which wave-like oscillation occurs.

Additionally or alternatively, a flow field on one of the outer sides of the individual plates can be characterized by the fact that it lies within an MEA reinforcement edge and in particular is surrounded and/or framed by it at least in sections. However, the MEA reinforcement edge is not opposite the flow field itself, but rather the actually active area of the MEA, in particular in the form of its electrolyte membrane. Reference is made by way of example to DE 20 2020 106 459 Ul and in particular to Figure 3B, which shows an MEA with a reinforcement edge that frames an active area of the MEA. However, the situation can be different with regard to the less deeply formed area assigned to the flow field, in which the MEA reinforcement edge and the GDL overlap one another.

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 takes place 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 level of the cooling fluid guidance when moving from the first to the second overlap region.

In a further embodiment, the cooling fluid guided by the third section of the cooling fluid distribution structure enters the second Overlap area, and in particular enters the second overlap area exclusively via the inner web-channel structure from the inside of the first individual plate.

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

A further variant provides that within the first section of the cooling fluid distribution structure, an inner side of the second individual plate is designed 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:

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

- there are no or at least fewer webs or channels that open into the second overlap area and/or that open into a possible third through-opening of the type described above; and/or

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

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

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 single plate.

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.

The invention is explained below with reference to the attached schematic figures. The same reference numerals can be used across the figures for similar or equivalent features. Figure 1 shows a perspective view of an electrochemical system according to an embodiment of this disclosure with a plurality of stacked separator plates with membrane electrode units arranged therebetween.

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.

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.

Figure 4 shows a perspective partial view of the separator plate of the first embodiment with a view of a fluid distribution region of a second individual plate, in particular anode plate, of the separator plate.

Figure 5 shows a schematic, simplified view of the fluid guide in a fluid distribution region of the separator plate according to the invention.

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.

Figure 7 shows a schematic, simplified view of the fluid guide in a fluid distribution region of the separator plate according to the invention.

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 stack 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 unit (MEA) 10 is arranged between 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.

In alternative embodiments, the 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 guided on or through the separator plates in an electrolyzer, an electrochemical compressor or a redox flow battery can differ from the media used for a fuel cell system.

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 x-y plane and thus perpendicular to the stacking direction (z-axis 7). The end plate 4 has a plurality of media connections 5 via which media can be fed to the system 1 and via which media can be removed from the system 1. These media that can be fed 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.

Figure 2 shows in perspective two adjacent separator plates 2 or bipolar plates, which can be included in an electrochemical system of the type of system 1 from Figure 1. The separator plates 2 correspond to an example from the prior art. However, the properties and features explained below in relation to this can also apply to the separator plates 2 according to the invention disclosed here or can be provided for them, unless otherwise mentioned or apparent.

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 only the individual plate 2a facing the viewer is visible in Figure 2, which forms the further Individual plate 2b is covered. The individual plates 2a, 2b can each be made from a metal sheet, e.g. from a stainless steel sheet. The individual plates 2a, 2b can be welded to one another, e.g. by laser welding or only connected when the stack is stacked. In particular, the design of fluid-conducting structures on the outside of the individual plate 2a facing the viewer can deviate from the structures according to the invention in the following figures 3 to 7.

The individual plates 2a, 2b have through-openings which are aligned with one another and 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 which 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. A cooling fluid can be introduced into the stack 6 or drained from the stack 6 via the lines formed by the through-openings 11a, for example. 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 with reaction gas and to drain the reaction products from the stack 6.

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 a flow field 17a with structures for guiding a reaction medium along the outside of the individual plate 2a on its outside facing the viewer in Figure 2. 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 outside of the Separator plate 2, the individual plate 2a facing the viewer also has two distribution areas 20. The distribution areas 20 each comprise structures that are designed to distribute a medium introduced from a first of the two through openings 11b into one of the distribution areas 20 via the active area 18 by means of the flow field 17 or to collect or bundle a medium flowing from the active area 18 to the second of the through openings 11b. In the latter case, the collecting distribution area 20 can also be referred to as a collection area.

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

Without this being shown separately in Figure 2, a cooling fluid distribution structure 19 formed and/or enclosed between the individual plates 2a, 2b also has distribution areas which overlap with the distribution areas 20 of the individual plates 2a, 2b. This cooling fluid distribution structure 19 is fluidically connected to a flow field or comprises this, 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.

The two through-openings 11b or the lines formed by the through-openings 11b through the plate stack of the system 1 are each in fluid communication with one another via passages 13b in sealing beads 12b, via the distribution structures of the distribution areas 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 in the sense of this disclosure. A fluid guided along the outside 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.

In an analogous manner, the two through holes 11c or the lines formed by the through holes 11c are formed through the plate stack of the System 1 are 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 in the sense 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.

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

In the following, fluid guides in a separator plate 2 according to an embodiment of the invention are explained using Figures 3 to 7. The separator plate 2 is basically designed analogously to Figures 1 and 2 and additionally has the features and special features explained below with regard to the fluid guides. In Figures 3 to 7, an area of a separator plate 2 outlined in dashed lines in Fig. 2 is considered, although reference is also made in part to the outside of the first individual plate 2b facing away from the viewer or to the internal cooling fluid structure.

Furthermore, in Figures 3 to 7 explained below, distribution areas 20 of the individual plates 2a, 2b and the cooling fluid distribution structure 19 are considered, each of which leads a fluid from one of the through openings 11a-c to a flow field 17, 17a-b. However, the statements also apply to the collecting distribution areas 20 (or collection areas) 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.

Figure 3 shows a schematically highly simplified 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 shown schematically in an area analogous to the dashed area in Fig. 2. The area shown 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.

The perspective of Figure 3 is rotated compared to Figure 2, as can be seen from the schematically illustrated positions of the through-openings 11a-c. In addition, the arrangement of these through-openings 11a-c makes it clear that the cooling fluid distribution structure 19 is oriented in a manner as if an outside of the first individual plate 2b from Figure 2 (not shown) were facing the viewer. The through-openings 11a-c again have the size ratios explained above.

The cooling fluid distribution structure 19 is delimited by the inner sides of the individual plates 2a, 2b facing each other. More precisely, opposing regions of these inner sides are spaced apart from each other to varying degrees, so that fluid-absorbing free spaces (i.e. flow spaces) are formed in the cooling fluid distribution structure 19. The cooling fluid distribution structure 19 also has web-channel structures (not shown), which form complementary shaped web-channel structures on the outer sides of the individual plates 2a, 2b, as explained above with reference to Figure 2.

The cooling fluid distribution structure 19 has three sections A, B, C, which are each essentially triangular in shape. The first section A and the third section C are each connected to the cooling fluid passage opening 11a in a fluid-conducting manner. The fluid-connecting passages through the sealing elements surrounding the cooling fluid passage opening 11a, as explained above, are not shown separately in Figure 3, but are nevertheless present. Two arrows 1A, 1C show a fluid inflow from the cooling fluid passage opening 11a into the first and third sections A, C. The size of the arrows illustrates the size ratios of these flows. It is thus clear that the fluid inflow 1A in the first th 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 is understood that a reverse flow direction is also possible.

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, 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 inside of the first individual plate 2b, which faces away from this fluid distribution region 21 or forms its inside, and by an opposite inside of the second individual plate 2a. The correspondingly delimiting section of the first individual plate 2b runs in sections in the plane of the flat surface of this individual plate 2b. The correspondingly delimiting section 30 of the second individual plate 2a (see Figure 4 discussed below), on the other hand, is predominantly formed opposite the plane of the flat surface of this individual plate 2a and in a direction pointing 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.

The second section B of the cooling fluid distribution structure 19 runs 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 are therefore opposite one another, which have 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 run in mutually crossing directions, which means an increased flow resistance for the cooling fluid.

The third section C of the cooling fluid distribution structure 19 runs 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 pointed out again that this third overlap region 24 and consequently also the third section C of the cooling fluid distribution structure 19 is merely optional. The structural designs of the first to third sections AC or the first to third overlap areas 15, 22, 24 are explained in more detail below with reference to Figures 4-7.

Figure 4 shows a section of the bipolar plate 2 with a view of the outside 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 area 23 and through a web-channel structure 40 on the outside of the second individual plate 2a. Merely as an example, the web-channel structure 40 has several outwardly projecting webs 27 and channels 29 enclosed between them, selected ones of which are each provided with a corresponding reference symbol. The webs 27 are, as shown, optionally interrupted in sections along their longitudinal extent, but can also extend continuously in the direction of the flow field 17. The second fluid distribution region 23, with the exception of the webs 27, extends in a flat surface plane Ea of the second individual plate 2a.

The second fluid distribution area 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. The step 32 is followed in the direction away from the flow field 17b by a section 42 of the second individual plate 2a which is raised relative to the plane surface Ea of the second individual plate 2a and which 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 above-mentioned section 30 of the second individual plate 2a, which proportionately delimits the first section A of the cooling fluid distribution structure 19.

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 also further spaced webs or wider channels than those present on the opposite inner side of the first individual plate 2b. The stiffening or supporting beads 44 also do not open into the second overlap region 22 or into the second through opening 11a. In the first overlap region 15 The second fluid is therefore not guided here.

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

Since the cooling fluid is guided primarily in the spanned 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. They can therefore, for example, be kept correspondingly narrow, whereby the second fluid distribution area 23 can be kept small overall.

Figure 5 shows a fluid flow in a schematically highly simplified representation, in particular the guidance of the hydrogen within a separator plate 2 according to the invention. In Figure 5, the viewing angle, as can be seen from the position of the through-opening 11b, is rotated compared to the second individual plate 2a shown in Figure 4 and corresponds essentially to that of Figure 3. Figure 5 reflects the extension 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 being indicated by means of 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.

Figure 6 shows a section of the outside of the bipolar plate 2 with a view of the first individual plate 2b, in particular the cathode plate, in the dashed area from Figure 2 according to an embodiment. This can be combined with the embodiment of Figure 4. A viewing angle is rotated in particular compared to Figure 3, as can be seen from the displayed 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 fed from the through-opening 11c via the first fluid distribution area 21 and guided through a web-channel structure 46 on the outside of the first Single plate 2b. For example only, the web-channel structure 46 has several outwardly projecting webs 27 and channels 29 enclosed between them, selected ones of which are provided with a corresponding reference symbol. The webs 27 have, as shown, an optional curved central region, but can also extend essentially without curvature in the direction of the flow field 17b. The first fluid distribution region 21 runs, with the exception of the webs 27, in a flat surface plane Eb of the first single plate 2b.

In Figure 6, one can also see the raised section 42 of the second individual plate 2a and the first section A of the cooling fluid distribution structure 19 formed thereby (see Figure 4). A part of the second fluid distribution region 23 can also be seen.

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, as shown in Figure 3, this overlap region 24 or this third section C is to be provided, a section 48 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.

Figure 5 shows a possible extension of this optional raised section 48, which is 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 in the direction of the opposite second individual plate 2a and promotes the level change described above when the cooling fluid passes from the optional third overlap region 24 into the second overlap region 22.

Figure 7 shows a schematically simplified representation of a fluid flow, in particular the guidance of the oxygen, within a separator plate 2 according to the invention. Figure 7 is a schematic simplified 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 extension 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 extension of the raised section 42 and the step 33 delimiting this section 42 is shown.

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. The stages 33 and 50 are also shown in Figure 3.

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 the process, it undergoes the change of level 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 angle size advantageously reduces the increase in flow resistance for the cooling fluid associated with the change of direction.

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

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 change of level described above and an analogous change in the direction of the flow of more than 90°. The fluid flows 2A, 2C flow through the second overlap region 22 in the direction of an (internal) flow field 17 of the cooling fluid distribution structure 19, crossing and mixing several times.

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 when passing from the first to the second overlap region 15, 22 than a cumulative flow cross-section when passing from the third to the second overlap region 24, 22. From the above, it is clear that the cooling fluid is guided deliberately 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 crossing in the second overlap region are reduced, 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 the electrochemical system to operate at a higher performance.

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 delimit 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 proportionately limited 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 sections (A, B) of the cooling fluid distribution structure (19) is larger than a flow cross section of a transition between the third and second sections (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 side 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 designed 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 inner side of the first single plate (2b); and/or - no or at least fewer webs or channels are present which open into the second overlap region (22) and/or which open into the third through-opening (11a) in a design of the separator plate (2) according to claim 6; and/or - Distances between webs and channel widths are larger than within the web-channel structure of the inner side of the first single 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).