Separator plate for an electrochemical system

Abstract

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

Description

[0001] for an electrochemical m

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

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

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

[0005] Furthermore, the separator plates usually each have at least one through-opening through which the media can be guided to or away from the electrochemical cells or membrane electrode assemblies (MEAs) arranged between adjacent separator plates of the stack.

[0006] From such a through-opening, a respective fluid is guided into a respective first distribution area by means of the structures described above, and from there into a flow field opposite the active area of ​​the cell or MEA. 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 to conduct a second fluid, e.g., a reaction gas, on a second outer side of the separator plate facing away from the first outer side, i.e., an outer side of a second individual plate. However, a cooling fluid is usually conducted in an interior space defined by the inner sides of the individual plates. The media are usually conveyed through the system by means of external pumps.

[0008] It has been shown that with previous solutions, fluid flow is sometimes only possible with increased flow resistance. This places greater demands on the external pumping power. Furthermore, it can lead to limitations in the overall performance of the electrochemical system.

[0009] An object of the present invention is therefore to limit pressure losses in the fluid flow of a separator plate and thus to improve the overall performance of an electrochemical system having a plurality of such separator plates.

[0010] This object is achieved by the subject matter of the independent claims. Advantageous further developments are specified in the dependent claims as well as in this description and the figures. Accordingly, a separator plate for an electrochemical system is proposed, comprising a first individual plate and a second individual plate, the first individual plate, which is in particular an anode plate, comprising:

[0011] - at least one first passage opening for passing a fluid through the separator plate;

[0012] - at least one distribution area;

[0013] - a flow field which is in fluid communication with the through-opening via the distribution area and which is configured to guide the fluid along a main flow axis; wherein the distribution area comprises:

[0014] - a connection area,

[0015] - a first portion defining a fluid connection between the through-opening and the connecting region and having a plurality of first webs and first channels formed between the first webs,

[0016] - a second section which defines a fluid connection between the connecting region and the flow field and which has a plurality of second webs and second channels formed between the second webs, wherein the connecting region is arranged between the first and second section of the distribution region such that each fluid exchange between the first and second section flows through the connecting region, wherein a width of the connecting region runs parallel to the main flow axis and the width is at least 1 mm and a maximum of 5 mm. Preferably, the width is between at least 2 mm and a maximum of 3 mm. Furthermore, none or a maximum of 7%, preferably a maximum of 5%, of the first webs and the second webs merge into one another through the connecting region.The connecting region can therefore be completely or at least substantially web-free or, in other words, at least web-reduced compared to the first and second sections.

[0017] This solution takes into account the fact that pressure losses in the fluid flow can occur primarily at the transition between the flow field and the distribution area. This results from multiple changes in the direction of the fluid flow and multiple transitions of the fluid flow between fluid-carrying structures at this transition. Until now, the design options for shaping this transition to reduce pressure losses have been limited. The completely or at least essentially web-free connection area increases this design flexibility, for example, because the first and second sections of the distribution area are largely structurally decoupled and can therefore be individually optimized with regard to their fluid flow.

[0018] For example, it is known that channel / web structures in the distribution areas and the flow field generally differ in terms of the number of webs and channels. Typically, the webs in the distribution area run at a different angle to the main flow axis than in the flow field, resulting in a smaller number of channels in the distribution area, even if the channel and web widths correspond to those of the flow field. A coarser structure is often chosen in the distribution area than in the flow field, for example, in the form of larger channel and web widths, since no material turnover and thus no power generation takes place in the distribution area.

[0019] The above circumstances currently mean that not all flow field ridges can continue directly into the distribution area. Usually, only selected ridges can transition directly from the flow field into the distribution area. Additional flow field ridges located between these selected ridges currently end at the transition to the distribution area.

[0020] For example, viewed perpendicular to the main flow axis, only every x-th ridge, where x is an integer > 0, can transition from the flow field into the distribution area. However, ridges of the flow field located between two adjacent x-th ridges currently end at the transition to the distribution area.

[0021] Such a web layout has the disadvantage that the web / channel width in the distribution area must be an integer multiple of the web / channel width in the flow field. This also results in the restriction that the number of webs in the flow field must be an integer multiple of the number of webs in the distribution area. This is one of the structural limitations that has so far made a pressure loss-optimized design of the transition area between the distribution area and the flow field difficult.

[0022] Instead, the invention provides for completely or at least largely dispensing with the connection of webs of the flow field with webs of the distribution area in the aforementioned transition region of the first individual plate, in particular for any or at least most of the connections that can be established in principle between all of these webs. Thus, preferably all or at least almost all of the webs of the flow field end at the transition to the distribution area. This results in a higher number and in larger flow cross-sections of fluid-conducting connections between the channels of the flow field and the distribution area. As a result, the achievable flow volume is increased. In addition, pressure equalization can take place between adjacent channels, thereby improving the even distribution of the volume flow across all channels of the flow field.

[0023] Furthermore, both the number of ribs and the channel / rib width in the distribution area and the flow field can be designed more independently of each other than was previously the case. In particular, the number of ribs in the flow field does not necessarily have to be an integer multiple of the number of ribs in the distribution area. This allows the structure of the distribution area to be optimized more freely than before, for example, with regard to fluid flow, uniform distribution, and pressure losses.

[0024] The first and second individual plates can have mutually facing inner sides that comprise or define a cooling fluid distribution structure. The webs and channels on an outer side of the respective individual plates can form complementarily shaped webs and channels on their respective inner sides. These complementarily shaped webs and channels can be encompassed by the cooling fluid distribution structure and / or guide the cooling fluid. The cooling fluid distribution structure can also have at least one distribution region and one flow field, which can each overlap with the distribution region and flow field of the first and / or second individual plates.

[0025] The first and second individual plates can each have a distribution region and a flow field for fluid guidance on their outer sides, wherein these distribution regions and flow fields preferably overlap in sections. The second individual plate can form a cathode plate and / or can carry oxygen or air as a first fluid on its outer side. The first individual plate can form an anode plate and / or can carry hydrogen or another fuel gas as a second fluid on its outer side. According to a further embodiment, a length of the completely or substantially web-free connecting region, which is measured along a longitudinal axis extending perpendicular to the main flow axis, is substantially as long as a length of the flow field measured along this longitudinal axis.This ensures that any fluid exchanged between the first and second sections of the distribution area always flows through the connecting area.

[0026] The width of the connecting area, i.e., the area through which the webs do not extend, is advantageously understood as a width in which the webs do not touch the MEA, its reinforcement edge, or the GDL at all. It therefore begins with the lowering of the first web and ends with the second web reaching its full height in the area of ​​the web crest, or vice versa. The width is preferably determined parallel to the aforementioned main flow axis.

[0027] A further development provides that at least the majority of the first webs each have an end facing the completely or substantially web-free connecting area, and a connecting line between these ends is straight. These are first webs that do not transition into second webs through the connecting area.

[0028] Alternatively or additionally, at least the majority of the second webs can each have an end facing the completely or substantially web-free connecting region, and a connecting line between these ends can be non-linear. These are second webs that do not transition into first webs through the connecting region. The connecting line can, for example, be corrugated. In particular, it can be periodically corrugated. The periodicity can result from a repeating sequence of differently shaped and / or dimensioned second webs. This sequence can, for example, be present in a direction transverse to the main flow axis.

[0029] By forming the webs so that the aforementioned connecting lines are created, the width dimensions of the completely or substantially web-free connecting region can be limited (in particular due to the straight connecting line of the ends of the first webs). On the other hand, the design flexibility for the second webs can be increased. The latter enables, for example, the formation of sufficiently large and suitably extending flow cross-sections of the cooling fluid distribution structure on the inner side of the first individual plates. The connecting lines can each define a boundary of the web-free connecting region. According to a further embodiment, at least the longest sections of the first webs run at an angle relative to the main flow axis that is greater than or equal to 70°. The smallest achievable intersection angle can be considered.

[0030] Alternatively or additionally, at least the longest sections of the second webs can extend at an angle relative to the main flow axis that is less than 45° and preferably less than 20°. Again, the smallest achievable intersection angle can be considered.

[0031] It has been shown that by means of such alignments of the first and second webs, a reliable and sufficient volume flow through the distribution area can be achieved with limited space requirements.

[0032] The longest sections of the first and second webs, respectively, can be straight. However, the ends, in particular of the second webs, can be non-straight and, in particular, curved and / or have enlarged or varying flow cross-sectional dimensions.

[0033] In a further development, at least the first webs are each at least three times, in particular at least five times, in particular at least seven times as long as they are wide, thus serving to provide direction and not just to support the MEA, its reinforcing edge, or the GDL, with the length and width dimensions each running parallel to a plane of the separator plate. This emphasizes that the first webs can be elongated and can provide a reliable flow guidance function over a corresponding length.

[0034] In a conventional manner, the plane of the planar surface of a respective individual plate can be defined, for example, by an edge of the individual plate or by those flat areas of the individual plate that are not deformed as a result of an embossing or deep-drawing process to form the web-channel structures or beads described herein. On the one hand, the planar surface planes can run in the neutral fibers of the corresponding sections of the plates; on the other hand, it is also possible to consider the surfaces of the relevant sections of the plates as planar surface planes. However, with the latter approach, it is important to note that, when considering distances, etc., the material thickness of only one of the two plates considered is taken into account.

[0035] According to one variant, the first webs have a greater height, measured perpendicular to the plane of the first individual plate, than the second webs. As a result, channels of the cooling fluid distribution structure, which are complementarily shaped by the first webs, can have correspondingly increased depths and consequently larger flow cross-sections. This can, as a design flexibility, allow, for example, that opposite the first webs on an inner side of the second individual plate there may be no channels or only smaller channels than opposite the second webs in order to provide sufficient flow cross-sections for the cooling fluid guided inside.

[0036] In one embodiment, the first section has a greater extension than the second section, with the extensions each running parallel to the main flow axis. In particular, the extension of the first section can be at least three times as large as the extension of the second section. Such dimensions of the first and second sections allow for a reliable and sufficient volume flow through the distribution area to be achieved within a limited space requirement.

[0037] It may be provided that the number of second webs is not an integer multiple of the number of first webs. Alternatively or additionally, the number of first webs may be less than half the number of second webs. This results in corresponding design flexibility for the first and second sections of the distribution area.

[0038] The second individual plate can have channels on its inner side opposite the completely or substantially web-free connecting region of the first individual plate, and in particular, channels bridging said connecting region. Consequently, the cooling fluid can be guided along the inner side of the connecting region in these channels. In this way, the cooling fluid can be exchanged between the flow field and the distribution region of the cooling fluid distribution structure, even if the completely or substantially web-free connecting region does not provide any channels for the cooling fluid on its inner side.

[0039] When we talk about a flow field here, this can refer to both the actual flow field and an overlap region that closes off the flow field toward the distribution area. Compared to the actual flow field, the cooling fluid channels in the overlap region can be less high, allowing sufficient space for the overlap of the GDL (explained below) and the MEA reinforcement edge.

[0040] In summary, a further development provides that the completely or substantially web-free connecting region of the first individual plate is opposite a region of the second individual plate which has at least sections of a plurality of webs formed in the second individual plate and channels formed between the webs.

[0041] The invention also relates to an electrochemical system having a plurality of separator plates according to any aspect described herein.

[0042] The invention is explained below with reference to the accompanying schematic figures. The same reference numerals may be used throughout the figures for similar or equivalent features.

[0043] Figure 1 shows a perspective view of an electrochemical system with a plurality of stacked separator plates with membrane electrode units arranged between them.

[0044] 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.

[0045] Figure 3 shows a perspective partial view of the separator plate of the first embodiment in the region of a distribution area of ​​a first individual plate, in particular anode plate, of the separator plate.

[0046] Figure 4 shows an orthogonal projection of the structural features of a part of the separator plate into a common plane.

[0047] Figure 5 shows in two sub-figures 5A, 5B a comparable orthogonal projection as Figure 4 and a corresponding sectional view.

[0048] Figures 6 and 7 each show views analogous to Figure 3 of separator plates according to further embodiments.

[0049] 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.

[0050] 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 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.

[0051] 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.

[0052] Fig. 2 also shows a known membrane electrode assembly (MEA) 10 arranged between these adjacent separator plates 2, wherein the MEA 10 in Fig. 2 is largely concealed by the separator plate 2 facing the viewer. The separator plate 2 is formed from two materially joined individual plates 2a, 2b, of which in Fig. 2 only the individual plate 2a facing the viewer is visible, which conceals the other individual plate 2b. The individual plates 2a, 2b can each be made of a metal sheet, e.g., a stainless steel sheet. The individual plates 2a, 2b can, for example, be welded to one another, e.g., by laser welding, or can be connected only when the stack is stacked. In particular, the design of fluid-conducting structures on the outer side of the individual plate 2a facing the viewer can differ in Fig. 2 from the structures according to the invention in the further figures below.

[0053] 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 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, for example, 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.

[0054] 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 first individual plate 2a 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.

[0055] Adjacent to the electrochemically active region 18 of the MEA, the individual plate 2a facing the viewer has, on its outer side facing the viewer, a flow field 17a with structures for guiding a reaction medium along the outer side of the individual plate 2a and along a main flow axis S. 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, the individual plate 2a facing the viewer also has two distribution regions 20a. The distribution regions 20a each comprise structures which are designed to distribute a medium introduced from a first of the two through-openings 11b into one of the distribution regions 20a by means of the flow field 17b over the active region 18 or to guide a medium introduced from the active region 18 orto collect or concentrate the medium flowing from the flow field 17a to the second of the through-openings 11b. In the latter case, the collecting distribution region 20a can also be referred to as a collection region. The fluid-conducting structures of the distribution regions 20a are also represented in Figure 2 by webs and channels extending between the webs and delimited by the webs.

[0056] 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 20a, b of the individual plates 2a, 2b. This cooling fluid distribution structure is fluidically connected to or encompasses a flow field, wherein this flow field overlaps with the flow fields 17a, b 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.

[0057] 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 20a, b and via the flow field 17a of the individual plate 2a facing the viewer in Figure 2.

[0058] This individual plate 2a is a first 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.

[0059] 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 second 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.

[0060] 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.

[0061] Figure 3 shows a section of the bipolar plate 2, looking toward the outside of the first individual plate 2a, preferably an anode plate, in the dashed area of ​​Figure 2. The viewing angle is rotated relative to Figure 2, as can be seen from the indicated position of the through-opening 11b in Figure 3. Only a cut-off portion of the distribution region 20a and the flow field 17a are shown. A fluid is guided into the flow field 17a from the through-opening 11b via the distribution region 20a and guided by a web-channel structure 46a on the outside of the second individual plate 2a. The flow field 17a has a main flow axis S, along which the fluid flows through the flow field 17a (see also main flow axis S in Figure 2).

[0062] The web-channel structure 46a has a plurality of outwardly projecting webs 27a, 37a as well as channels 29a, 39a enclosed between them, selected ones of which are each provided with a corresponding reference symbol. The deepest regions of the channels 29a, 39a run in the plane of the flat surface of the second individual plate 2a. More precisely, the web-channel structure 46a has first webs 27a and first channels 29a in a first section 21a of the distribution area 20a, which run from the through-opening 11b to a connecting area 60. The first webs 27a are, as shown, optionally interrupted in sections along their longitudinal extent within the distribution area 20a, but can also extend continuously.

[0063] Furthermore, the web-channel structure 46a has second webs 37a and second channels 39a, which extend from the connecting region 60 to the flow field 17a and continue there as webs and channels of the flow field 17a or merge into corresponding webs and channels. The second webs 37a and second channels 39a extend into a second section 22a of the distribution region 20a. The first and second sections 21a, 22a are connected via the connecting region 60, so that all fluid exchanged between the first and second sections 21a, 22a must pass through the connecting region 60.

[0064] In the embodiment of Fig. 3, the connecting region 60 is completely web-free. It therefore extends as a gap-like, free region between the first and second sections 21a, 22a. Furthermore, it preferably has a consistently constant height and / or a consistently planar shape.

[0065] The number of second webs 37a in the second section 22a is greater than the number of first webs 27a in the first section 21a. For example, at least five or at least nine times as many second webs 37a as first webs 27a can be provided.

[0066] The flow field 17a 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 the main flow direction. Alternatively, the webs and channels of the flow field 17a could also be wave-shaped and run alongside one another with a similar wave shape and along the main flow direction S. The wave shape can oscillate uniformly around the main flow axis S and / or the main flow axis S can define a central axis of the wave shape around which wave-like oscillation occurs. Additionally or alternatively, and not limited to the specific details of this exemplary embodiment, the flow field 17a can be characterized in that it lies within an MEA reinforcement edge and, in particular, is surrounded and / or framed by it at least in sections.However, the flow field 17a itself is not opposed by the MEA reinforcement edge, but by the actual active region of the MEA, particularly 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 framing an active region of the MEA. However, the situation may 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.

[0067] The completely web-free connecting region 60 in the example of Fig. 3 preferably runs in the plane of the first individual plate 2a. The webs 27a, 37a accordingly extend to the plane of the first individual plate 2a at the edges of the web-free connecting region 60. The webs 27a, 37a do not extend along the main flow axis S through the connecting region 60 and are therefore not directly connected to one another and do not merge into one another. Instead, they end on a respective adjacent side of the connecting region 60 and are spaced apart from one another by the latter.

[0068] Fig. 3 shows that ends of the first webs 27a, which border the connecting region 60, can be connected by means of a straight connecting line 62. In the example shown, the connecting line 62 runs perpendicular to the main flow axis S.

[0069] In contrast, the ends of the second webs 37a, which border the connecting region 60, can be connected by means of a non-rectilinear connecting line 64. In particular, this connecting line 64 is wave-shaped and, moreover, in particular periodically wave-shaped. This results from the fact that the ends of the second webs 37a, which border the connecting region 60, define a regularly repeating sequence of ends shaped in a specific manner and extending to a specific extent parallel to the main flow axis S. Thus, some of the second webs 37a have enlarged and curved end sections 33 at the transition to the web-free connecting region 60.

[0070] The web-free connecting region 60 shown in Fig. 3 is formed in a continuous manner, in particular in such a way that it has a continuous region without webs. This region can extend substantially orthogonally to the main flow axis S. Figure 3 shows a longitudinal axis L3 of the web-free connecting region 60, which runs orthogonally to the main flow axis S. A dimension of the web-free connecting region 60 along this longitudinal axis L3 is at least as large as a dimension of the flow field 17a along the longitudinal axis L3. This emphasizes that the fluid must always flow through the web-free connecting region 60 in order to switch between the first and second sections 21a, 22a.

[0071] A width dimension B of the web-free connecting region 60 extends orthogonally to the longitudinal axis L3 and along the main flow axis S. Due to the uneven extension of the ends of the second webs 37a adjacent to the web-free connecting region 60—see the wavy connecting line 64—the width dimension B of the web-free connecting region 60 varies along the longitudinal axis L3. Thus, the width B fluctuates between at least 1 mm and up to 5 mm.

[0072] Viewed in the same width direction, it can be seen that both the extension E1 of the first section 21a and the extension E2 of the second section 22a are significantly larger than the width dimension B of the web-free connecting region 60 in Fig. 3, for example, at least twice as large or at least three times as large. Furthermore, the extension E1 of the first section 21a is at least twice and preferably at least three times as large as the extension E2 of the second section 22a.

[0073] Figure 3 further shows the various orientations of the first and second webs 27a, 37a based on respective angles Wl, W2. These angles Wl, W2 define orientations of the webs 27a, 37a relative to the main flow axis S. A longitudinal axis LI is plotted for one of the first webs 27a. This runs at an angle Wl relative to the main flow axis S, which is less than 90° when considering the smallest achievable intersection angle.

[0074] A longitudinal axis L2 is also shown for one of the second webs 37a. This axis is angled relative to the main flow axis S by an angle W2, which, however, is significantly smaller than the angle W1 of the first webs 27a. The angle W2 is shown schematically greatly enlarged and can be significantly smaller. It can also be 0°.

[0075] Figure 3 further shows that the first webs 27a are at least three times, in particular at least five times, in particular seven times as long as they are wide, wherein the length and width dimensions each run parallel to a flat surface plane of the first individual plate 2a.

[0076] Fig. 4 shows an orthogonal projection of a section of the separator plate 2 of the first embodiment, which is oriented analogously to Fig. 2, in a plane parallel to the flat surface planes of the individual plates 2a, 2b. The view corresponds to a view through an area of ​​the separator plate 2 that includes a transition between the flow field 17a and the distribution area 20a of the first individual plate 2a and thus also a part of the connecting area 60, which is completely web-free in this embodiment, wherein the area in which the webs are completely lowered is schematically shown hatched from top left to bottom right. Positions of the distribution areas 20a-c and flow fields 17a-c on the outer and inner sides of the first and second individual plates 2a, b are shown. These overlap at least in sections.

[0077] Furthermore, the positions and dimensions of overlaps of the channel-web structures 46a, b on the outer sides of the first and second individual plates 2a, b as well as the cooling fluid distribution structure 19 jointly delimited thereby can be seen. Those webs and channels from Fig. 4 which are not present in Fig. 3 are webs and channels of the second individual plate 2b. The essentially or completely web-free connecting region 60 in the first individual plate 2a is thus opposite a region in the second individual plate 2b through which both channels 30c on the inner side of the first individual plate 2a and channels (not further designated) on the outer side of the first individual plate 2a extend, which channels are formed in the region of the rear side of the webs between the channels 30c. The essentially or completely web-free connecting region 60 is therefore advantageously formed in only one of the two individual plates of the separator plate.

[0078] Three channels 27c of the cooling fluid distribution structure 19 are shown, each shaped complementarily to webs on the outer side of the second individual plate 2b. The channels 27c each have an optionally widened curved region 52, which, however, could also not be widened compared to adjacent segments of the first channels 27c.

[0079] The curved region 52 of each channel 27c is fluidically connected to three channels 30c on the inside of the first individual plate 2a. These channels 30c are shaped complementarily to second webs 37a on the outside of the first individual plate 2a. Not all of the second channels 30c are marked with a corresponding reference symbol in Figure 4.

[0080] For the uppermost channel 27c in Fig. 4, the transition areas to the second channels 30c are shown hatched. In the case of the two upper channels 30c, the hatching marks an area in which the open ends of the second channels 30c are opposite the curved area 52 and the channels 30 consequently open into the curved area 52.

[0081] It can be seen that the curved regions 52 of the second individual plate 2b partially overlap with the web-free connecting region 60 and extend through it, or in other words, bridge it. This allows cooling fluid to flow through the cooling fluid distribution structure 19, even though there are no webs on the outside of the first individual plate 2a in the web-free connecting region 60 that could form complementarily shaped channels of the cooling fluid distribution structure 19. In other words, and not limited to the details of this exemplary embodiment, channels formed opposite the web-free connecting region 60 on the inside of the second individual plate 2b provide a fluid connection between a distribution region 20c and the flow field 17c of the cooling fluid distribution structure 19.

[0082] Figure 5A essentially shows the same section as Figure 4, but here we will now look in more detail at the determination of the width B of the connecting region 60. Section AA from Figure 5A, which is shown not to scale in Figure 5B, illustrates some details in this regard. The region hatched from bottom left to top right in Figure 5A represents the region in which there is no contact between the webs and the MEA reinforcement edge or the GDL on the corresponding outer side, i.e. the actual connecting region 60. Accordingly, to determine the width, on the one hand, the regions 270 of the first webs 27a closest to the second webs 37a, which have the maximum height of the webs 27a, are considered, and on the other hand, the regions 370 of the second webs 37a closest to the first webs 27a, which also have the maximum height, whereby the height can vary, as can be seen from Figure 5B.In the present example with fully rounded land crests, these are, on the distribution area 20a side, the land crest lines 280 of the first lands 27a closest to the second lands 37a up to the respective beginning of their lowering. The connection between corresponding line segments on land crest lines 280 is parallel to the main flow axis S. On the flow field 17a side, the regions of maximum height of the lands 37a facing the distribution area 20a are the end points of the land crest lines 380 at the points 375 where the lowering of the land crests begins to form the connecting area 60. The width B can be determined, for example, along one of the double arrows in Figure 5A; see also Figure 5B.

[0083] Figures 6 and 7 each show views of separator plates 2 according to further embodiments, analogous to Figure 3. The only difference from the embodiment of Figure 3 is that the connecting region 60 is not completely web-free in this case. Apart from that, all explanations regarding Figure 3 also apply to the identical features and structures of the embodiments of Figures 6 and 7.

[0084] In both embodiments of Figures 6 and 7, the connecting region 60 is not completely web-free. Instead, in the case of Figure 6, there are, for example, two outer pairs of first and second webs 27a, 37a, viewed along the longitudinal axis L3, which extend into the connecting region 60 to merge into one another. In the case of Figure 7, there is, for example, a middle pair of first and second webs 27a, 37a, viewed along the longitudinal axis L3, which extend into the connecting region 60 to merge into one another. All other first and second webs 27a, 37a end at the connecting region 60, analogous to the exemplary embodiment of Figure 3. Thus, the majority of the first and second webs 27a, 37a do not merge into another of the first and second webs 27a, 37a, and the connecting region 60 is web-free over a large part of its area.

[0085] The number and positioning of the first and second webs 27a, 37a merging into one another are only examples in Figures 6 and 7 and may differ from the variants shown.

Claims

Patent claims 1. Separator plate (2) for an electrochemical system (1), comprising a first individual plate (2a) and a second individual plate (2b), the first individual plate (2a) comprising: - at least one first through-opening (11b) for passing a fluid through the first individual plate (2a); - at least one distribution area (20a); - a flow field (17a) which is in fluid communication with the through-opening (11b) via the distribution region (20a) and which is configured to guide the fluid along a main flow axis (S); wherein the distribution region (20a) comprises: - a connecting area (60), - a first section (21a) defining a fluid connection between the through-opening (11b) and the connecting region (60) and having a plurality of first webs (27a) and first channels (29a) formed between the first webs (27a), - a second section (22a) which defines a fluid connection between the connecting region (60) and the flow field (17a) and which has a plurality of second webs (37a) and second channels (39a) formed between the second webs (37a), wherein the connecting region (60) is arranged between the first and second section of the distribution region (20a) in such a way that each fluid exchange between the first and second section (21a, 22a) flows through the connecting region (60), wherein a width (B) of the connecting region (60) runs parallel to the main flow axis (S) and the width (B) is at least 1 mm and at most 5 mm, and wherein none or at most 7%, preferably at most 5%, of the first webs (27a) and the second webs (37a) merge into one another through the connecting region (60).

2. Separator plate (2) according to claim 1, wherein a length of the connecting region (60) measured along a longitudinal axis (L3) extending perpendicular to the main flow axis (S) is substantially as large as a length of the flow field (17a) measured along this longitudinal axis (L3).

3. Separator plate (2) according to claim 1 or 2, wherein at least the majority of the first webs (27a) each have an end facing the connecting region (60) and a connecting line (62) of these ends is straight; and / or wherein at least the majority of the second webs (37a) each have an end facing the connecting region (60) and a connecting line (64) of these ends is not straight.

4. Separator plate (2) according to one of the preceding claims, wherein at least the respective longest sections of the first webs (27a) run at an angle (Wl) relative to the main flow axis (S) which is greater than or equal to 70° and / or wherein at least the respective longest sections of the second webs (37a) run at an angle (W2) relative to the main flow axis (L2) which is less than 45°, preferably less than 20°.

5. Separator plate (2) according to one of the preceding claims, wherein at least the first webs (27a) are at least three times as long as they are wide, wherein the length and width dimensions each run parallel to a flat surface plane of the first individual plate (2a).

6. Separator plate (2) according to one of the preceding claims, wherein the first webs (27a) have a greater height measured perpendicular to the flat surface plane of the first individual plate (2a) than the second webs (37a).

7. Separator plate (2) according to one of the preceding claims, wherein the first section (21a) has a greater extension (Ei) than the second section, wherein the extensions (Ei, E2) each run parallel to the main flow axis (S), in particular wherein the extension (Ei) of the first section (21a) is at least three times as large as the extension (E2) of the second section (22a).

8. Separator plate (2) according to one of the preceding claims, wherein the number of second webs (37a) is not an integer multiple of the number of first webs (27a); and / or wherein the number of first webs (27a) is less than half the number of second webs (37a).

9. Separator plate (2) according to one of the preceding claims, wherein the connecting region (60) of the first individual plate (2a) is opposite a region of the second individual plate (2b) which has at least portions of a plurality of webs formed in the second individual plate (2b) and channels formed between the webs.

10. Electrochemical system (1) comprising at least one separator plate (2) according to one of the preceding claims.

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