Separator plate and bipolar plate for an electrochemical system

Abstract

Separator plate (24, 26) for an electrochemical system, comprising: - at least one first through-hole (22a) for passing a first reaction fluid through the separator plate (24, 26), at least one second through-hole (22b) for passing a second reaction fluid through the separator plate (24, 26) and at least one third through-hole (22c) for passing a cooling fluid through the separator plate (24, 26); - on an outer side of the separator plate (24, 26): at least one distribution area (28), one flow field (30) and at least one distribution side channel (44); wherein the distribution area (28) fluidly connects the first through-opening (22a) and a main area (32) of the flow field (30); wherein the distribution side channel (44): - connects the first through-opening (22a) and a secondary area (38) of the flow field (30) in a fluid-conducting manner, and - extends at least section by section along a circumferential section of the first and / or the second and / or the third passage opening (22a-c) facing away from the distribution area (28); wherein the secondary area (38) has a plurality of flow field subsidiary channels (40) and webs (42) formed between each pair of flow field subsidiary channels (40), wherein the webs (42) each form a complementary shaped cooling fluid side channel (41) on the inside of the separator plate (24, 26), wherein the distribution side channel (44) and / or the flow field side channel (40) has at least one sectional elevation (50, 52, 54) of a channel bottom (43), and wherein the at least one elevation (50, 52, 54) on the inside of the separator plate (24, 26) forms a section of a fluid connection between at least one of the cooling fluid side channels (41) and the third through-opening (22c).

Description

[0001] The invention relates to a separator plate and a bipolar plate, each 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.

[0002] Known electrochemical systems of the type mentioned typically comprise a stack of electrochemical cells, each separated from the others by bipolar plates. In the context of such stacks, two single-layer separator plates are often joined to form a bipolar plate, with each separator plate forming a single layer of the bipolar plate. The separator plates can be joined by a metallurgical bond, e.g., by one or more welds, particularly by one or more laser welds.

[0003] The separator plates or bipolar plates can be used, for example, for the electrical contacting of the electrodes of the individual electrochemical cells (e.g. fuel cells) and / or for the electrical connection of adjacent cells (series connection of the cells).

[0004] The separator plates or bipolar plates can each have or form structures designed, for example, to supply the electrochemical cells arranged between adjacent separator plates or bipolar plates with one or more media and / or to remove reaction products. In particular, a cooling fluid can be guided through a space between the individual plates of a bipolar plate by means of these structures. 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 a cooling fluid. Within the scope of this disclosure, the terms "medium" and "fluid" may be used synonymously.

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

[0006] From such a through-opening, a fluid is guided by means of the structures described above into a first distribution area 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 via a second distribution area, also called a collection area, back to an outlet through-opening. An example of this can be found in DE 20 2016 107 302 U1.

[0007] It is known to guide a first fluid, e.g., a fuel, on a first outer surface of the bipolar plate (i.e., an outer surface of a first separator plate) and a second fluid, e.g., a reaction gas, on a second outer surface of the bipolar plate (i.e., an outer surface of a second separator plate). In contrast, a cooling fluid is typically guided in an interior space bounded by the inner surfaces of the separator plates. The fluid-guiding structures on the respective outer surfaces of the separator plates form complementary structures on their inner surfaces, which guide the cooling fluid.

[0008] However, it has been shown that the performance of such electrochemical systems can still be optimized. For example, the fluid channels between the through-holes and a flow field still occupy a significant proportion of the surface area on each side of a bipolar plate. This area is not available as an active part of the cell and therefore does not directly contribute to its performance.

[0009] One object of the present invention is therefore to improve the performance of an electrochemical system with a plurality of such separator plates and bipolar plates.

[0010] This problem is solved by the subject matter of the independent claims. Advantageous developments are specified in the dependent claims, as well as in this description and in the figures.

[0011] Accordingly, a separator plate for an electrochemical system is proposed, wherein the separator plate can, for example, form a single-layer bipolar plate on its own or can be combined with another separator plate to form a double-layer bipolar plate. The separator plate has: - at least one first through-hole for passing a first reaction fluid through the separator plate, at least one second through-hole for passing a second reaction fluid through the separator plate and at least one third through-hole for passing a cooling fluid through the separator plate; - on an outer side of the separator plate: at least one distribution area, one flow field and at least one secondary distribution channel; wherein the distribution area fluidly connects the first through-opening and a main area of ​​the flow field; where the secondary distribution channel: - connects the first through-opening and a secondary area of ​​the flow field in a fluid-conducting manner, and - extends at least partially along a circumferential section of the first and / or the second and / or the third passage opening facing away from the distribution area; wherein the secondary area has a plurality of flow field subsidiary channels and webs formed between each pair of flow field subsidiary channels, wherein the webs each form a complementarily shaped cooling fluid secondary channel on the inside of the separator plate, wherein the distribution side channel and / or the flow field side channel has at least a sectional elevation of a channel bottom, and wherein at least one raised section on the inside of the separator plate forms a section of a fluid connection between at least one of the cooling fluid side channels and the third through-hole.

[0012] According to the invention, the secondary distribution channel utilizes a surface area of ​​the separator plate for fluid supply to the flow field, which lies outside conventional distribution areas and also outside the distribution area according to the invention. Consequently, a previously unused fluid supply path is provided for the flow field, and more precisely for its secondary area. Furthermore, it has been recognized according to the invention that at least sections of the secondary distribution channel can run in areas of the separator plate that can be used as such an additional fluid supply path without significantly impairing other structural features or functions of the separator plate.

[0013] The partial fluid supply of the flow field via the distribution side channel allows for a reduction in the number of channels and / or the area proportion of the distribution zone to the total plate area compared to existing solutions. This enables an increase in the size of the flow field and thus an increase in the performance of the electrochemical system.

[0014] A further advantage arises from the fact that the distribution duct can be continuously flowed through, at least in sections, without fluid accumulating and / or becoming stagnant. Otherwise, this fluid could potentially freeze. In contrast, existing solutions often contain areas with such stagnant fluid accumulations.

[0015] For example, existing solutions have gaps between adjacent beads, which can also fill with fluid from the first through-opening. The fluid can flow in but not out, and therefore remains in the gaps. The secondary channel according to the invention can also include such gaps, but provides a drainage option via the connection to the flow field, thus enabling flow through the gaps.

[0016] The additionally provided multiple flow field secondary channels can advantageously provide a type of throttling effect. In particular, by dividing the fluid flow from the distribution secondary channel into the multiple flow field secondary channels (or vice versa, from the flow field secondary channels into the distribution secondary channel), the fluid flow can be selectively throttled. This can limit the risk of the distribution secondary channel, and consequently the flow field secondary channels, being significantly oversupplied compared to other channels in the flow field and / or the distribution area. As explained below, at least one riser can also provide such a throttling effect.

[0017] The at least one elevation according to the invention advantageously enables the adjacent region of the flow field to be reliably and extensively cooled. It has been shown that without such an elevation, a cooling fluid flow on the inside of the separator plate, and particularly within the interior of a bipolar plate, cannot reach all regions of the inside of the adjacent region of the flow field. In particular, not all of the internal channels formed by the webs there (cf. the claimed cooling fluid secondary channels) can be supplied with cooling fluid. For example, without such an elevation, a cooling fluid path through external channels of the separator plate, which in turn form internal webs, can be blocked or at least significantly reduced before the cooling fluid path reaches the inside of the adjacent region of the flow field.

[0018] The through-openings can be configured according to existing solutions. The first to third through-openings can be positioned between the nearest distribution area and an outer edge of the separator plate. The first to third through-openings can be arranged sequentially and / or in series perpendicular to a main flow axis described below, preferably spaced apart. In a manner known per se, the first to third through-openings can be dimensioned differently, particularly with respect to their areas. Additionally or alternatively, their centroids can be positioned at different locations along the main flow axis.

[0019] The first through-opening and the third through-opening can accommodate the second through-opening between them, e.g., viewed perpendicular to the main flow axis.

[0020] The separator plate can have distribution areas on both sides of the flow field, wherein an arrangement of through-openings disclosed herein, including preferably a secondary channel disclosed herein, can be provided between each distribution area and an outer edge of the separator plate nearest to it.

[0021] The first and second through-holes can each be a through-hole for a fluid that flows along the outer surface of the separator plate and / or a bipolar plate. The terms "outer surface" and "inner surface" of the separator plate are assigned to the surfaces of the separator plate according to their function in a bipolar plate.

[0022] In the case of a bipolar plate, a first separator plate disclosed herein can, in particular, form a cathode plate and / or carry oxygen or air as a first fluid on its outer surface. A second separator plate of the bipolar plate can form an anode plate and / or carry hydrogen as a second fluid on its outer surface. Alternatively, however, it is also possible that the first separator plate is configured as an anode plate and / or carries hydrogen as a first fluid on its outer surface. The second separator plate can then be configured as a cathode plate and / or carry oxygen or air as a second fluid on its outer surface.

[0023] The secondary distribution channel can be fluidly connected to the primary through-opening, for example, via a penetration through a sealing bead surrounding the through-opening that is either enclosed by or connected to it. In particular, the secondary distribution channel and / or the secondary area of ​​the flow field may not be fluidly connected to the primary through-opening, or at least not exclusively via the distribution area. For example, fluid exiting the primary through-opening may branch out into the secondary distribution channel and the distribution area.

[0024] With reversed flow direction, the first through-opening can be supplied simultaneously from both the secondary distribution channel and the distribution area. The volume fraction of the fluid entering or exiting the secondary distribution channel can be less than the corresponding volume fraction entering or exiting the distribution area. In particular, the volume fraction of the secondary distribution channel can be less than 10%, more specifically less than 8%, and preferably less than 5% of the volume fraction carried by the distribution area.

[0025] The secondary distribution channel can extend section by section from a point where it is fluid-conductingly connected to the first through-opening in a direction away from the distribution area. In particular, the secondary channel can extend section by section towards an outer edge of the separator plate. Alternatively or additionally, it can extend section by section towards a side of the first through-opening facing away from the distribution area.

[0026] The secondary distribution channel can run at least partially at an angle to a main flow axis and, in particular, substantially perpendicular to it. The main flow axis can be an axis along which fluid is guided in the flow field (especially in both the secondary and main regions). The main flow axis can be straight. In the case of non-straight, for example, wave-shaped channels in the flow field, the main flow axis can run parallel to a mean trajectory of the channels and / or to a central axis of the waveform and / or define such a mean trajectory or central axis. Additionally or alternatively, the main flow axis can run parallel to or form a symmetry axis and / or longitudinal axis of the flow field.

[0027] The secondary distribution channel can optionally extend along several of the through-openings. In particular, it can run between a circumferential section of the second and / or third through-opening facing away from the distribution area and the nearest outer edge of the separator plate, and / or in the direction of the second and / or third through-opening. This illustrates that the first and subsequent through-openings are preferably positioned near different longitudinal sides of the separator plate. These longitudinal sides can extend along, and in particular parallel to, the main flow axis through the flow field.

[0028] The flow field can have a plurality of fluid channels in a manner known per se. These can run side by side, in particular straight and parallel to each other and / or with a similar corrugation. The fluid channels preferably run along the main flow axis of the flow field as described above.

[0029] The flow field can be characterized, for example, by the fact that all the webs and channels it encompasses are straight and run parallel to each other and parallel to a main flow direction of the cooling fluid through the flow field, as defined in particular by the main flow axis. Alternatively, the webs and channels can also be wave-shaped and run side by side and along the main flow axis with a similar wave pattern.

[0030] Additionally or alternatively, the flow field can be characterized by lying within an MEA reinforcement edge of the cell and, in particular, being at least partially surrounded and / or framed by it. However, the flow field itself is preferably not located opposite the MEA reinforcement edge, but rather opposite the actually active area of ​​the MEA, especially in the form of its electrolyte membrane. Reference is made by way of example to DE 20 2020 106 459 U1 and, in particular, to the drawing marked 3B, which shows an MEA with a reinforcement edge that frames an active area of ​​the MEA.

[0031] The fluid can be guided through the openings perpendicular to a plate plane and / or the plane of the separator plate. In a manner known per se, the plane of a single-layer separator plate can be defined, for example, by an edge of the separator plate or by those flat areas of the separator plate that are not deformed by an embossing or deep-drawing process to form the web-channel structures or beads described herein. On the one hand, the planes of the planes can run along 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 the planes of the planes. However, in the latter case, it is important to ensure that, in the case of a two-layer bipolar plate and when considering distances or similar, the material thickness is only taken into account for one of the two plates under consideration.

[0032] In principle, more than two secondary flow channels can be provided, with a bridge forming between each pair of adjacent secondary flow channels. If only exactly two secondary flow channels are provided, it is understood that only a single bridge can be formed between these two secondary flow channels.

[0033] The internal fluid connection formed by the raised section can, in particular, comprise or define a section of a cooling fluid path that connects the third through-hole and at least one of the cooling fluid auxiliary channels. Other sections of this cooling fluid path can, for example, be formed by internal channels defined by webs of the distribution area. It can be provided that this raised section, or any plurality of such raised sections, enables the only fluid connection between the third through-hole and the at least one cooling fluid auxiliary channel.

[0034] According to a further development, at least one elevation is formed in one of the flow field auxiliary channels and the distance of the elevation measured along a main flow axis of this flow field auxiliary channel to a nearest fluid inlet and / or outlet area of ​​the flow field is at most 5 cm, in particular at most 2 cm, in particular at most 1 cm, and / or at most 10%, in particular at most 6% of a total length of the flow field auxiliary channel.

[0035] The elevation can therefore be located close to an end region of the secondary flow channel along the main flow axis, where the end region corresponds to a fluid inlet and / or outlet area. For example, the transition from the transition zone (which will be examined in more detail later) to the actual flow field can be considered a fluid inlet and / or outlet area. Alternatively, the line where both plates have the lowest rib height on their outer surface, closest to the adjacent through-openings, can be considered a fluid inlet and / or outlet area, even if this line may also belong to the transition or distribution zone.

[0036] This arrangement of the lift enables comprehensive cooling in the secondary region of the flow field, meaning cooling that also cools the electrochemically active area of ​​the flow field over a large area in the secondary region. Figuratively speaking, the internal cooling in the flow direction of a secondary channel of the flow field can thus begin early and / or be maintained until shortly before the end of the secondary channel.

[0037] The main flow axis of the secondary flow channel can be defined analogously to and / or parallel to the main flow axis of the flow field. It can correspond to a longitudinal axis of the secondary flow channel.

[0038] According to a further development, the separator plate has a second distribution channel that fluidly connects the first through-opening and the adjacent area of ​​the flow field. This channel preferably extends at least partially along a circumferential section of the second and / or third through-opening facing the distribution area. This creates an additional fluid connection between the first through-opening and the flow field away from the distribution area.

[0039] According to a further development, the at least one elevation has a length in the direction of extension of a flow field secondary channel of at most 5% of the length of the shortest distribution secondary channel up to the boundary of the flow field or the flow field secondary channel; and / or the at least one elevation extends with a length in the direction of extension of a flow field secondary channel of at most 2 cm, in particular at most 1 cm or at most 0.5 cm, along a main flow axis of the flow field secondary channel. This limits any effects of the elevation on the flow through the flow field secondary channel. It has been shown that with the specified values ​​the desired cooling effect can be reliably achieved and / or enhanced without unduly impeding the flow through a flow field secondary channel.

[0040] According to a further embodiment, the average height of the at least one raised section, measured perpendicular to the plane of the surface, is at most 80%, preferably at most 60%, of the maximum height of a structure, measured perpendicular to the plane of the surface, that bounds the secondary distribution channel or secondary flow field channel in which the at least one raised section is formed. If the raised section is formed in a cathode plate, the measured average height of the at least one raised section is preferably at most 50% of the bounding structure. Examples of such structures are explained below. Even in this embodiment, the desired effects of the at least one raised section can be reliably achieved without unduly impeding the flow through the secondary region of the flow field.

[0041] According to a further development, at least one raised section is formed in one of the secondary flow channels and connects two webs that define the secondary flow channel. In this way, a reliable and compact internal fluid connection of the cooling fluid secondary channels formed by these webs can be provided.

[0042] According to a further development, one of the webs of the secondary area of ​​the flow field and / or a cooling fluid secondary channel formed on its inner side is designed to exchange cooling fluid with a cooling fluid secondary channel of an opposing separator plate. In particular, these can jointly define a cooling fluid path and / or define a section of such a path by creating a corresponding gap within a two-layer bipolar plate. This ensures particularly comprehensive cooling fluid flow along the inner side of the secondary area and thus correspondingly pronounced cooling.

[0043] According to a further development, the elevation is formed in one of the flow field secondary channels and connects a bridge bounding this flow field secondary channel and a structure bounding the main area of ​​the flow field, whereby cooling fluid can be guided on the inside of this structure.

[0044] In particular, the elevation can be formed in a secondary flow channel located closest to, and for example directly adjacent to, the main flow field area. This secondary flow channel can, for instance, run between the web of the secondary area that defines this channel and the structure that defines the main area. Such positioning of the elevation ensures a compact and effective internal cooling fluid supply to the secondary area, since the structure defining the main area typically carries cooling fluid on its internal surface.

[0045] According to one variant, the structure bounding the main area is an outermost rib of the main area. The outermost position can be located, in particular, perpendicular to a main flow axis through the flow field and / or be defined along a corresponding transverse axis.

[0046] It should be noted that such an outermost rib of the main region, or more generally the structure bounding the main region, cannot be assigned to the secondary region. Typically, this outermost rib of the main region and / or more generally the structure bounding the main region only binds a single secondary flow channel, in particular a secondary flow channel immediately adjacent to it. In contrast to the ribs of the secondary region of the flow field, the outermost rib or the bounding structure of the main region is thus typically not formed between two secondary flow channels. Consequently, it typically does not form a rib of the secondary region of the flow field within the meaning of this disclosure.

[0047] A boundary element may be arranged between the secondary region of the flow field and the outer edge of the separator plate. Such a boundary element also only limits a single secondary flow field channel, in particular the secondary flow field channel furthest from the main region. This boundary element also typically does not form a rib of the secondary region of the flow field within the meaning of this disclosure.

[0048] As already mentioned, only exactly two secondary flow channels can be provided, between which only a single rib can be formed. The remaining boundary can then be formed by the outermost rib of the main area and / or, more generally, by the structure bounding the main area on the one hand, and the boundary element on the other. Unlike the space between the rib and the outermost rib of the main area, no elevation should be arranged between the rib and the boundary element.

[0049] According to a further development, the secondary area comprises at least three jetties and at least two flow field bypass channels, each of which is at least partially or partially bounded by two adjacent jetties. For example, the two adjacent jetties are connected to each other by at least one partial elevation of the channel bed of the flow field bypass channel bounded by it. The at least two flow field bypass channels can be adjacent to each other and separated by a common jetty.

[0050] The limitation of the elevation, at least partially or at least in part, by the webs can include the webs limiting, for example, only one side and / or only one circumferential section of the elevation and, in particular, of its plan view. For instance, two opposite sides of the elevation can be limited by the webs. Two other opposite sides of the elevation, however, can merge into the flow fluid channel encompassing this elevation and, in particular, into its channel bed.

[0051] By providing multiple risers, the cooling fluid can be distributed, in particular, transversely to the main flow axis of the flow field within the secondary area. Specifically, the cooling fluid can thus reach not only the inner secondary cooling fluid channels immediately adjacent to the main area of ​​the flow field, but also, viewed transversely to the main flow axis, the outermost and, in particular, the outermost inner secondary cooling fluid channels of the secondary area.

[0052] In general, any channels disclosed herein can form recessed areas relative to adjacent ribs, designed for fluid guidance. Each channel base can form a surface area with minimal height in at least selected subregions of the separator plate. Conversely, the rib surfaces can form maximally raised surface areas in at least selected subregions of the separator plate. The aforementioned subregions of the separator plate can each encompass several square centimeters, in particular more than 10 cm². 2 They can comprise multiple webs as well as multiple channels. The web surfaces and a respective channel base can be connected via flanks, which can optionally be assigned to the webs or the channels. The height can be measured orthogonally to the plane of the separator plate.

[0053] Additionally or alternatively, the bridge surface can form an installation area for further components of the electrochemical system, in particular for an MEA, a PTL and / or a GDL.

[0054] In connection with the aforementioned plurality of possible lifts, a further development provides that the respective lifts, at least one of each, within the secondary flow channels are distributed along a common axis that runs orthogonally to a main flow axis of the secondary flow channels and / or the flow field. In other words, the respective lifts of the secondary flow channels can be arranged in a row and / or in alignment along the common axis. This axis can, in particular, be straight. Furthermore, a distribution along the axis can be provided, especially when more than two such lifts are provided. In this way, the passage of cooling fluid to internal cooling fluid channels of the secondary area, even those located away from the main flow field, can be enabled over short distances. This reduces losses in the cooling capacity of the cooling fluid (i.e.,a premature warming of this), which can generally increase with increasing length of the cooling fluid flow paths.

[0055] According to a further development, at least one of the uplifts within the secondary flow channels has a main uplift flow axis that runs at an angle of less than 60° or less than 45° to a main flow axis of the secondary flow channels. In particular, the main flow axis of the secondary flow channel in which the uplift is located can be considered here. The main uplift flow axis can be an axis along which the cooling fluid is primarily guided on the inside of the uplift. Specifically, it can be a longitudinal axis of the uplift and / or of an internal cooling fluid path or cooling fluid path segment defined by it. For example, this axis can correspond to or define a shortest flow path along which the cooling fluid can flow on the inside of the uplift.

[0056] By appropriately angling the lift, and more precisely its main flow axis relative to a main flow axis of the secondary flow channels, the cooling fluid flow can be guided inside in a turbulence-free manner and / or via the shortest possible flow paths.

[0057] This in turn improves the cooling capacity of the adjacent area of ​​the flow field.

[0058] According to a further development, in the case of a possible plurality of lifts, as discussed in particular in the context of the foregoing embodiment, the internal flow cross-section of one of the lifts that is further away from the main area is smaller than that of the correspondingly different lift. The latter can be arranged closer to the main area. Here, distances to the main area can be considered along an axis that runs transversely to a main flow axis according to any variant disclosed herein.

[0059] The inner flow cross-section can be formed, in particular, by a cooling fluid path or cooling fluid path segment located on the inside of the lift. Specifically, the inner cooling fluid path or cooling fluid path segment can be shaped complementarily to the lift.

[0060] The decreasing flow cross-section with increasing distance from the main area can help to achieve a substantially constant pressure drop of the cooling fluid despite the branching of cooling fluid in all cooling fluid path sections. This allows the internal flow rate to remain essentially constant compared to the flow cross-sections of the rises located closer to the main area, or it can limit any decrease in this flow rate to an acceptable level.

[0061] According to a further development, the separator plate comprises a continuous lowered transition area that includes end sections of the distribution bypass channel and the distribution area transitioning into the flow field, wherein in the flow field there is a mean channel height h1 measured perpendicular to the plane of the plan surface and in the transition area there is a maximum channel height h measured perpendicular to the plane of the plan surface. max is, where h max ≤ 0.95·h1.

[0062] The lowered transition area can accommodate a reinforced edge area of ​​an MEA adjacent to the separator plate. This enables uniform or targeted compression of the membrane, particularly in the active area of ​​the electrochemical cell in question.

[0063] The lowered transition area can, for example, be assigned to the distribution area, unless otherwise specified or apparent herein.

[0064] According to a further development, at least one raised section is formed in a portion of the distribution bypass channel that extends into the transition zone. Analogous to the above explanations regarding the positioning of the raised sections, this allows for an early internal introduction and / or late internal discharge of cooling fluid relative to the flow path through the bypass zone, so that the bypass zone can be cooled internally over long distances and thus correspondingly effectively.

[0065] According to a further development, the distribution secondary channel branches, for example, in the transition area into several channel sections, each separated by web sections. The channel sections transition into the flow field secondary channels, and the web sections transition into the webs of the secondary area. At least one raised section is formed, at least partially, in one of the channel sections and is connected to a structure that delimits the distribution area, along the inner surface of which cooling fluid can be guided. The raised section can be limited, at least partially or at least partially, by the structure that delimits the distribution area. A further limitation of the raised section, at least partially or at least partially, can be achieved, for example, by one of the web sections.

[0066] According to a further development, the length of at least one elevation measured along a main flow axis of a secondary flow channel is less than the length of the transition zone measured along this main flow axis.

[0067] According to further training, a second distribution area secondary channel has been trained, which: - connects the first through-opening and a secondary area of ​​the flow field in a fluid-conducting manner, and - extends at least in sections along a circumferential section of the second and / or third passage opening facing the distribution area.

[0068] The invention also relates to a bipolar plate for an electrochemical system, comprising a first separator plate according to any of the aspects disclosed herein and a second separator plate, which can also be configured according to any of the aspects disclosed herein. The inner surfaces of the first and second separator plates face each other, so that the cooling fluid can be guided between them.

[0069] Also revealed is an electrochemical system with a plurality of separator plates according to every aspect described herein.

[0070] The invention is explained below with reference to the accompanying schematic figures. The same reference numerals can be used across figures for similar or equivalent features. If a figure shows several instances of a particular feature, for the sake of clarity only selected instances may be provided with a reference numeral that is generally assigned to that feature. Fig. Figure 1 shows a perspective view of an electrochemical system with a large number of stacked bipolar plates. Fig. Figure 2 shows a perspective view of two bipolar plates of a similar system. Fig. 1 with a membrane electrode assembly (MEA) arranged between the separator plates. Fig. Figure 3 is a representation of a fluid guidance along a partial area of ​​a bipolar plate according to an embodiment of the invention, wherein the bipolar plate comprises two separator plates designed according to the invention. The Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11 to Fig. Figures 12 each show a detailed view of a separator plate according to further embodiments of the invention. Figure 13 shows a sectional view through a bipolar plate according to an embodiment of the invention.

[0071] Fig. Figure 1 shows an electrochemical system 1 of the type proposed here, comprising a plurality of identical metallic bipolar plates 2, which are formed by two joined separator plates. The bipolar plates 2 are arranged in a stack 6 and stacked along a z-direction 7. The bipolar plates 2 of the stack 6 are clamped between two end plates 3, 4. The z-direction 7 is also called the stacking direction.

[0072] In the present example, system 1 is a fuel cell stack. Each pair of adjacent bipolar plates 2 of the stack 6 encloses an electrochemical cell between them, which serves, for example, to convert chemical energy into electrical energy. To form the electrochemical cells of system 1, a membrane electrode assembly (MEA) 10 is arranged between each pair of adjacent bipolar plates 2 of the stack 6 (see below). Fig. 2) The MEA 10 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.

[0073] In alternative embodiments, system 1 can also be configured as an electrolyzer – either as a polymer electrolyte membrane (PEM) electrolyzer, e.g., for hydrogen production, or as an anion exchange membrane (AEM) electrolyzer, e.g., for CO2 conversion – as a compressor or as a redox flow battery. Separator plates can also be used in these electrochemical systems. In the case of an electrolyzer, single-layer separator plates can be used as bipolar plates. The structure of these separator plates can correspond to the structure of the separator plates described in more detail here, even though the media guided on or through the separator plates in an electrolyzer, an electrochemical compressor, or a redox flow battery may differ from the media used in a fuel cell system.

[0074] The z-axis 7, together with the x-axis 8 and y-axis 9, defines a right-handed Cartesian coordinate system. The bipolar plates 2 each define a plate plane, with the plate planes of the bipolar plates 2 being aligned parallel to the xy-plane and thus perpendicular to the stacking direction (z-axis 7). The end plate 4 has a multitude of media connections 5 through which media can be supplied to and discharged from system 1. These media 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.

[0075] Fig. Figure 2 shows in perspective two adjacent bipolar plates 2, which are connected to an electrochemical system of the type of system 1. Fig. 1 may be included. The bipolar plates 2 correspond to an example from the prior art. However, the properties and features explained below in relation to them may also apply to, or be provided for, the bipolar plates and / or separator plates disclosed herein according to the invention, unless otherwise stated or apparent.

[0076] Fig. Figure 2 also shows a known membrane electrode assembly (MEA) 10 arranged between these adjacent bipolar plates 2, wherein the MEA 10 is in Fig. 2 is largely obscured by the bipolar plate 2 facing the viewer. The bipolar plates 2 are each formed from two single-layer separator plates 2a, 2b joined together, of which in Fig. 2. Only the separator plate 2a facing the viewer is visible, concealing the other separator plate 2b. The separator plates 2a and 2b can each be made of a metal sheet, e.g., a stainless steel sheet. The separator plates 2a and 2b can be welded together, e.g., by laser welding, or joined only when the stack is assembled. The design of fluid-carrying structures on the viewer-facing outer surface of the separator plates 2a is particularly important. Fig. 2 may differ from the structures according to the invention shown in the following further figures.

[0077] The separator plates 2a, 2b have aligned through-holes which form through-holes 11a-c of the bipolar plate 2. When multiple bipolar plates 2 are stacked, the through-holes 11a-c form conductors that extend through the stack 6 in the stacking direction 7 (see Fig. 1) Typically, each of the conduits formed by the through-openings 11a-c is in fluid communication with one of the ports 5 in the end plate 4 of system 1. For example, a cooling fluid can be introduced into or discharged from the stack 6 via the conduits formed by the through-openings 11a. The conduits formed by the through-openings 11b and 11c, on the other hand, can be configured to supply the electrochemical cells of the fuel cell stack of system 1 with fuel and reaction gas, and to discharge the reaction products from the stack 6.

[0078] To seal the through-openings 11a-c against the interior of the stack 6 and against the environment, the separator 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 them. The second separator plate 2b has, on the side facing the viewer, Fig. On the opposite side of the bipolar plate 2, corresponding sealing beads 12a-c are also provided for sealing the through-openings 11a-c (not shown). Alternative sealing systems, such as elastomer seals, can also be used.

[0079] Adjacent to the electrochemically active area of ​​the MEA, the separator plate 2a facing the viewer has a flow field 17a on its outer surface facing the viewer, with structures for guiding a reaction medium along the outer surface of the separator plate 2a. These structures are in Fig. 2 in the form of a multitude of bridges and channels running between the bridges and bounded by the bridges.

[0080] For simplicity, the area of ​​the separator plate opposite the electrochemically active region of the MEA, which is essentially formed by the flow field 17a, is also referred to as the active region 18. On the outer surface of the bipolar plate 2 facing the observer, the separator plate 2a also has two distribution regions 20. Each distribution region 20 comprises structures designed to distribute a medium introduced into one of the distribution regions 20 from a first of the two through-openings 11b via the flow field 17a over the electrochemically active region of the MEA, or to collect or concentrate a medium flowing from the electrochemically active region of the MEA or from the flow field 17a towards the second of the through-openings 11b. In the latter case, the collecting distribution region 20 can also be referred to as a collection region.The fluid-carrying structures of the distribution areas 20 are in . Fig. 2 channels also run through footbridges and between the footbridges and are bordered by the footbridges.

[0081] Without this being in Fig. As shown separately in Figure 2, a cooling fluid distribution structure 19 formed and / or enclosed between the separator plates 2a, 2b also has distribution areas 20c, which overlap with the distribution areas 20a,b of the individual plates 2a, 2b. This cooling fluid distribution structure 19 is fluidically connected to a flow field 17c, which overlaps with or is enclosed between the flow fields 17a,b of the outer surfaces of the separator plates 2a, 2b, or encompasses this flow field 17c. The rib-channel structures on the outer surfaces of the separator plates 2a, 2b form complementary rib-channel structures on the corresponding inner surfaces and thus complementary rib-channel structures of the cooling fluid distribution structure 19.

[0082] The two through-openings 11b and the conduits formed by the through-openings 11b through the stack of plates of system 1 are each connected via feedthroughs 13b in sealing beads 12b, via the distribution structures of the distribution areas 20 and via the flow field 17a, which is visible to the observer of the Fig. The two separator plates 2a facing each other are in fluid contact. A fluid guided along the outside of this separator plate 2a is preferably hydrogen, so that the through-openings 11b are preferably hydrogen through-openings 11b. This is particularly evident from the fact that the hydrogen through-openings 11b have the smallest cross-section compared to the other through-openings 11a, 11c.

[0083] Similarly, the two through-openings 11c and the conduits formed by the through-openings 11c through the stack of plates of system 1 are each connected via corresponding corrugated penetrations 13c, via corresponding distribution structures and via a corresponding flow field 17b on an outer side of the surface visible to the observer. Fig. The two separator plates 2b facing away from each other are in fluid contact. This separator plate 2b is a first separator plate 2b within the meaning of this disclosure. A fluid guided along the outside of this separator plate 2b is preferably air or oxygen, such that the through-openings 11c are preferably air or oxygen through-openings 11c.

[0084] The through-holes 11a, or rather the conduits formed by the through-holes 11a through the plate stack of system 1, are each in fluid communication with one another via a cavity 19 enclosed or surrounded by the separator plates 2a, 2b, which forms the cooling fluid distribution structure 17c. This communication is facilitated, for example, by feedthroughs 13a. This cavity 19, or rather this cooling fluid distribution structure 17c, serves to guide a cooling fluid through the bipolar plate 2, in particular to cool the electrochemically active area of ​​the MEA. The through-holes 11a are therefore cooling fluid through-holes, which is particularly evident from their average cross-sectional size compared to the other through-holes 11b, 11c.

[0085] Fig. Figure 3 shows a top view of a partial area of ​​a bipolar plate 20 according to an embodiment of the invention. This bipolar plate 20 is largely analogous to the example of Fig. 2, but exhibits in particular the following differences with regard to the fluid guidance on its outer and inner sides and with regard to the formation of the flow field.

[0086] The section shown corresponds to one of the areas in Fig. 2 outer end regions along the x-axis 8, where this end region includes three through-openings 22a, 22b, 22c. The positioning of these through-openings 22a-c clarifies that the view opposite Fig. 2 is essentially rotated by 90°.

[0087] In Fig. Figure 3 shows the outer surface of a first separator plate 24 of the bipolar plate 20, facing the viewer. The other separator plate 26 of the bipolar plate 20 is separated by the in Fig. 3. Topmost first separator plate 24 concealed.

[0088] All of those revealed here Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig. 12 to Fig. Figure 13 relates to such a sub-area or end-area. It is understood, however, that the opposite end-area, comprising three further passage openings 22a-c, can also be designed analogously and exhibit analogous fluid flows. However, the flow directions are typically reversed there (see explanation of Fig. 2).

[0089] The first passage opening 22a in Fig. 3, apart from its non-restrictive form, is essentially analogous to the through-opening 11c from Fig. 2 formed and exemplifies an air or oxygen passage opening. The passage opening 22c in Fig. 3, apart from its non-restrictive form, is essentially analogous to the passage opening 11a from Fig. 2 formed and a cooling fluid passage opening. The passage opening 22b in Fig. 3, apart from its non-restrictive form, is essentially analogous to the passage opening 11b from Fig. 2 formed and an exemplary hydrogen passage opening. The through-openings 22a-c are distributed transversely to a main flow axis S as explained below. For illustrative purposes, they, or rather their respective centroids (not shown separately), are offset from one another along the main flow axis S.

[0090] It can be seen that the first through-opening 22a is arranged near a first outer edge 31 of the separator plate 24, this outer edge 31 extending along the main flow axis S and consequently corresponding to a longitudinal side of the separator plate 24. Opposite this is a second outer edge 33 of the separator plate 24, in particular opposite it along an axis (not shown) running transversely to the main flow axis S. This second outer edge 33 also consequently corresponds to a longitudinal side of the separator plate 24.

[0091] Also shown is a third outer edge 35 of the separator plate 24, which runs transversely to the main flow axis S and consequently corresponds to a transverse side. The fourth outer edge, which is opposite this along the main flow axis S and forms the other transverse side, is shown in Fig. 3 not shown.

[0092] A distribution area 28 on the outer surface of the first separator plate 24 is shown, which fluidly connects the through-opening 22a to a flow field 30, and more precisely to a main area 32 of this flow field 30. The flow field 30 is also formed on the depicted outer surface of the first separator plate 24. Both the distribution area 28 and the main area 32 of the flow field 30 have a multitude of fluid-carrying channels 34, 34.1, as well as webs 36, 36.1 positioned between and separating the channels 34, 34.1. Only selected of these structures are shown in Fig. 3 is marked with a corresponding reference numeral. In a manner known per se, each channel 34 of the distribution area 28 is fluid-conductingly connected to several channels 34.1 of the main area 32 of the flow field 30. In particular, each channel 34 of the distribution area 28 transitions into several channels 34.1 of the main area 32 of the flow field 30 (or vice versa) and / or each channel 34 of the distribution area 28 branches into several channels 34.1 of the main area 32 of the flow field 30.

[0093] The channels 34.1 of the flow field 30 are elongated and, in the example shown, straight. They each run parallel to each other and parallel to a main flow axis S of the flow field 30. The channels 34 of the distribution area 28, on the other hand, clearly run at an angle to this main flow axis S.

[0094] The flow field 30, which, according to the above, extends in an electrochemically active region of the bipolar plate 2, also has a secondary region 38. This secondary region 38 also has channels in the form of cooling fluid secondary channels 40. These also run parallel to the main flow axis S of the flow field 30, as is illustrated by the extent of a main flow axis S' of a selected cooling fluid secondary channel 40.

[0095] The cooling fluid auxiliary channels 40 are separated from each other by webs 42 of the auxiliary area 38. More precisely, the webs 42 separate each pair of immediately adjacent cooling fluid auxiliary channels 40 that run parallel and side by side.

[0096] Out of Fig. Figure 3 clarifies that the secondary area 38 of the flow field 30 is significantly smaller than the main area 32 and also comprises significantly fewer cooling fluid secondary channels 40 compared to the channels 34.1 of the main area 32. For example, the number of cooling fluid secondary channels 40 cannot exceed 10% and, in particular, cannot exceed 5% of the number of channels 34.1 of the main area 32.

[0097] Additionally or alternatively, a width B1 of the main area 32 measured transversely to the main flow axis S of the main area 32 is at least ten times and in particular at least twenty times as large as a corresponding width B2 of the secondary area 38.

[0098] In the example shown, the secondary section 38 is not fluidly connected to the through-opening 22a via the distribution section 28. Instead, a fluid connection to the through-opening 22a is established via a secondary distribution channel 44, marked by a dashed line. This channel runs, for example, along a circumferential section of the through-opening 22a that is not directly facing the distribution section 28, and, in particular, along a section facing away from it, as well as, for example, along the other through-openings 22b-c. The course of the dashed line makes it clear that the secondary distribution channel 44 has a branched shape and, in particular, does not run purely without branches or as a single strand. However, this may be provided according to other embodiments not shown. The depicted course is generally not restrictive. The secondary distribution channel 44 can consist of the feedthroughs 13 surrounded by a wavy line, which are analogous to Fig. 2 pointing towards the distribution area 28, can be supplied, additionally or alternatively the fluid can be supplied via the optional feedthroughs 13.1 and / or 13.2.

[0099] The arrowhead of the dashed line of the distribution side channel 44 indicates that Fig. 3 specifically concerns a case in which fluid from the through-opening 22a is supplied to the flow field 30 and not vice versa. It is understood, however, that the flow direction can also be reversed.

[0100] Fluid is guided via the distribution side channel 44 past an outermost web 36' of the distribution area 28 and through an exemplary cross-section-reduced connecting section 45 of the distribution side channel 44 into the secondary area 38 of the flow field 30. The outermost web 36' forms an exemplary structure bounding the distribution area 28. It transitions into an outermost web 36.1' of the main area 32 of the flow field 30. This outermost web 36.1' forms an exemplary structure bounding the main area 32.

[0101] In Fig. Figure 3 also shows an optional second distribution channel 49, the course of which is marked by a dashed line. This channel also connects the first through-opening 22a fluid-conductingly to the secondary area 38 of the flow field 30. This distribution channel 49 is also optionally configured as multi-stranded and / or branched, but can also be configured as unbranched and / or single-stranded.

[0102] In particular, the second distribution branch 49 has a first section 49.1 that runs along a circumferential section of the cooling fluid passage opening 22c facing the distribution area 28. Fluid from the passage opening 22a can be introduced directly into this section, for example via the feedthroughs 13, as already shown in Fig. 2 are shown, or via an optional separate passage 13.3 pointing towards the first section 49.1. Furthermore, the second distribution branch 49 has a second section 49.2, which runs along a circumferential section of the hydrogen passage opening 22b facing the distribution area 28. This second section 49.2 opens near the branch 30 into the connecting section 45 or another adjacent section of the first distribution branch 44. At its other end, the second section 49.2 opens into the first section 49.1.

[0103] Furthermore, the second distribution channel 49 optionally has a section 49.3 extending between the through-openings 22b,c, which opens into the first distribution channel 44 and also into the second section 49.2. This occurs at or near the same end of the second section 49.2 with which it opens into the first section 49.1. Even if fluid is supplied to the secondary area 30 via the second distribution channel 49, the secondary area 30 is predominantly supplied via the first distribution channel 44. As a general aspect not limited to the details of this embodiment, the first and second distribution channels 44, 49 preferably serve exclusively as the fluid-conducting connection between the through-opening 22a and the secondary area 30.However, the first and second distribution side channels 44, 49 are specifically not designed to connect the through-opening 22a and the main area 32 in a fluid-conducting manner, and / or the first and second distribution side channels 44, 49 are not designed to introduce fluid into the distribution area 28. Accordingly, the first and second distribution side channels 44, 49 cannot generally be considered part of the distribution area 28.

[0104] At the latest in the secondary section 38, the incoming fluid is divided and guided into four secondary flow channels 40. The two central secondary flow channels 40 are each bounded by two webs 42 of the secondary section 38. The two outer secondary flow channels 40, considered perpendicular to the main flow axes S, S', are each bounded on one side by one of the webs 42 of the secondary section 38. A further boundary on the other side is formed in Fig. 3 left fall through the outermost pier 36.1' of the main area 32 of the flow field 30. In the Fig. In the 3 right case, such a further limitation is effected by an adjacent limiting element 46.

[0105] This limiting element 46 is optionally connected to a circumferential outermost sealing bead 48 via transverse connecting webs 90. The transverse connecting webs 90 prevent fluid from flowing past the flow field 30 on the outside of the separator plate 24.

[0106] Guiding the fluid through the comparatively narrow connecting section 45, as well as its distribution across several secondary flow channels 40, each provides a throttling effect. This can advantageously be used to selectively align the flow rates through the first secondary distribution channel 44 and / or the second secondary distribution channel 49 with the flow rates of the channels 34 in the distribution area 28.

[0107] Fig. Figure 3 is a schematic view, in particular insofar as exemplary structural profiles in a distribution area 28b are also shown on the outer side of the further separator plate 26 facing away from the viewer. The view thus corresponds to a view through the bipolar plate 2 and / or an orthogonal projection of the fluid guides on the respective outer sides of the two separator plates 24, 26 into a common plane.

[0108] In the distribution area 28b, channels 34b and webs 36b are again provided to connect the through-opening 22b fluidically to a fluid-conducting flow field 30b (not shown separately) on the outside of the second separator plate 26. This fluid connection can, in principle, be designed according to examples from the prior art. Alternatively, analogous to the example disclosed here, it can also have at least one secondary distribution channel 44, 49 and a flow field divided into a main and secondary area 32, 38.

[0109] It has been shown that the distribution areas 28, 28b are at least partially opposite each other, or, in other words, intersect, in a manner known per se. This forms a partial fluid connection on the respective inner surfaces of the separator plates 24, 26, which allows cooling fluid to flow to and / or from the through-opening 22c. More precisely, the respective webs 36, 36b of the distribution areas 28, 28b form complementary shaped inner channels in which the cooling fluid can be guided. Starting from the through-opening 22c, cooling fluid flows along the inner channels of the two distribution areas 28, 28b in the direction of the flow field 30, and more precisely towards the inner surface of its main section 32. The cooling fluid also flows through the area where, as mentioned, the inner channels of the distribution areas 28, 28b intersect.

[0110] However, such a configuration of the distribution areas 28, 28b does not readily guarantee that cooling fluid can also be guided along the inside of the secondary area 38 of the flow field 30. In particular, this does not readily guarantee a fluid connection between the through-opening 22c and the in Fig. Three cooling fluid auxiliary channels 41, which are not separately visible, are produced. The latter are formed complementarily on the inside by a respective web 42 of the auxiliary area 38. Insufficient cooling of the auxiliary area 38 can lead to impairment or destruction of the MEA and thus impair the performance of the entire electrochemical system.

[0111] One possibility for providing a cooling fluid connection to the cooling fluid auxiliary channels 41 of the auxiliary area 38 is in Fig. 3 by extended end sections of inner channels of the further separator plate 26. This is shown below by reference to Fig. Section 6 explains this in more detail. The following figures also illustrate various other possibilities for producing such cooling fluid compounds. These figures show... Fig. 4-12 each sub-areas of a fundamentally analogous to Fig. 3 formed bipolar plate 20, wherein these sub-areas in particular comprise a fluid inlet and / or outlet area of ​​the secondary area 38 the flow field 30, i.e. an end area of ​​the secondary area 38. Likewise, the illustrated sub-areas comprise the connection section 45 described above.

[0112] In the Fig. In the embodiment shown in Figure 4, a limiting element 46 of the secondary region 38 and the outermost webs 36', 36.1' of the main region 32 and the distribution region 28 are again visible. Also indicated are the first distribution secondary channel 44 and the connecting section 45, which extends into or out of the secondary region 38. The secondary region 38 comprises four flow field secondary channels 40. Also shown are the webs 42 of the secondary region 38 that separate these flow field secondary channels 40. As mentioned, these webs 42 each form internal cooling fluid secondary channels 41 that are not separately visible. Similar cooling fluid secondary channels 41 are shown in particular in the sectional view described in more detail below. Fig. 13 recognizable.

[0113] A in Fig. The bridge 42 of the secondary area 38, closest to the main area 32, is connected to the outermost bridge 36' of the distribution area 28 via a first elevation 50 and / or transitions into the aforementioned outermost bridge 36' via this elevation 50. This elevation 50 protrudes from an adjacent channel bed 43 of a secondary flow field channel 40 closest to the main area 32. This channel bed 43 may, in particular, run in a plane of the separator plate 24.

[0114] In other words, the raised section 50, viewed orthogonally to a plane of the visible first separator plate 24, protrudes from the channel bed 43, the channel bed 43 forming at least a locally lowest area on the outside of the first separator plate 24. Conversely, the raised section 50 has a lower height than the webs 42 of the secondary area 38, the height again being measured orthogonally to the plane of the visible surface (see also the one discussed below). Fig. 11). The webs 42 and in particular their outermost web surfaces facing the viewer form at least a locally highest area of ​​the outside of the first separator plate 24.

[0115] As can be seen from the perspective view of this embodiment explained below, in Fig. As illustrated in Figure 9, a section of the web 68 with a reduced height compared to the webs 38 is arranged between the raised section 50 and the web 38, but which has a greater height than the raised section 50.

[0116] As a general feature of this disclosure, not limited to the present embodiment, any elevation disclosed herein, as well as the elevation 50 in Fig. 4. are bounded at least on one side and, in particular, at least on two sides by the channel bed of an adjacent channel. These two sides may be opposite each other. The remaining sides, in particular the two further opposite sides of a raised section with a substantially rectangular plan, may be bounded by an adjacent elevated structure, as previously described by reference to Fig. 3. Explained by way of example.

[0117] The first raised section 50 is located at least partially within the connecting section 45 of the fluid auxiliary channel 44. Fluid can flow through the first raised section 50 into the adjoining flow field auxiliary channel 40 (or vice versa). Simultaneously, the raised section 50 forms an internal recessed area that defines a cooling fluid path along which the cooling fluid can be guided. In particular, the cooling fluid can be transferred from an internal recessed area formed by the outermost web 36' of the distribution area 28 into the cooling fluid auxiliary channel 41, which is internally defined by and complementary to the one in Fig. The uppermost web 42 of the secondary area 38 is formed. In this way, the elevation 50 establishes at least a partial fluid connection and / or at least a partial section of such a connection between this cooling fluid secondary channel 41 and the through-opening 22c.

[0118] Optionally, further elevations 52, 54 are also provided. These are each designed as local elevations relative to the adjacent channel bed 43, but have a reduced height compared to the webs 42. Accordingly, these are designed to allow flow over them on the outside, but provide recessed sections on the inside for the flow of cooling fluid.

[0119] A second raised section 52 connects internally and fluid-conductingly the cooling fluid auxiliary channels 41, which are formed by the in Fig. 4 upper and middle webs 42 are formed. A third raised section 54 connects the cooling fluid auxiliary channels 41 internally and fluid-conductingly, which are formed by the in Fig. The second and third raised sections 52, 54 are formed between and merge into the aforementioned raised sections 42. Consequently, the second and third raised sections 52, 54 are each bounded on at least two sides, and in particular on opposite sides, by the aforementioned raised sections 42. In contrast to the first raised section 50, the second and third raised sections 52, 54 are not arranged in line with and / or along a longitudinal axis L of the respective adjacent raised sections 42. Instead, they are specifically offset and / or perpendicular to this axis.

[0120] By means of the second and third lifting points 52, 54, cooling fluid can be drawn from the inside out. Fig. The uppermost cooling fluid secondary channel 41 is also directed into the further cooling fluid secondary channels 41 (or vice versa), which are formed by the middle and lowermost web 42. Fig. 4 are formed on the inside.

[0121] It is further shown that the second and third elevations 52, 54 are arranged along a common straight axis A. This advantageously reduces the length of the cooling fluid flow path, in particular until it reaches the Fig. 4 lowest cooling fluid secondary channel 41 reached.

[0122] Furthermore, it can be seen that all of the raised sections 50, 52, 54 are positioned near the connecting section 45. This connecting section 45 can be encompassed by, and / or form, a fluid inlet and / or outlet region 47 of the flow field 30, depending on the flow direction, and in particular by its secondary region 38. In other words, the raised sections 50, 52, 54 are thus positioned near an end of the secondary region 38, this end being located, for example, along a longitudinal axis L of the web or a main flow axis S or S'. As explained previously, this enables effective cooling over a large length of the secondary region 38.

[0123] For the sake of completeness, it should be mentioned that in Fig. 4 in turn the cross connecting webs 90 between the limiting element 46 and sealing bead 48 are recognizable.

[0124] Fig. Figure 5 shows an analogous view to Fig. 4, wherein this embodiment is characterized by a modified arrangement and shape of the raised sections 50, 52, 54. In this case, a first raised section 50 is formed analogously to the second and third raised sections 52, 54 described above, extending laterally from and / or transversely to the webs 42, 36.1' that define it. One of these webs is the outermost web 36.1' of the main region 32 of the flow field 30. A second and third raised section 52, 54 are each, in principle, analogous to the example from Fig. 4 positioned. All of the lifts 50, 52, 54 are in turn arranged along a common straight axis A, which runs transversely, more precisely orthogonally, to a main flow axis S'.

[0125] As shown, the bulges 50, 52, 54, and more precisely the cooling fluid paths formed on their inner surfaces, optionally exhibit different flow cross-sections. For example, a cooling fluid path formed on the inner surface of the first bulge 50 has the largest flow cross-section compared to the inner cooling fluid paths of the other bulges 52, 54. A maximum, average, and / or minimum flow cross-section of each bulge 50, 52, 54 can be considered and compared. In the example shown, the flow cross-sections of the respective bulges 50, 52, 54 decrease along their extent in the direction of the Fig. 5 lowest or outermost rib 42 and in particular continuously. However, this is not mandatory and, for example, there could also be a constant flow cross-section within a rise, see Fig. 10. As in Fig. As shown in Figure 10, this can also be achieved while maintaining the comparatively decreasing flow cross-sections between the elevations 50, 52, 54 as described above with increasing distance from the outermost pier 36.1' of the main area 32.

[0126] As previously explained, a reduction in the flow cross-section according to Fig. 5 and also Fig. 10 at least partial compensation of the decreasing amount of cooling fluid to be conveyed with increasing distance from the outermost bridge 36.1' due to the respective elevation.

[0127] Fig. Figure 6 shows a further embodiment, in which the dashed lines indicate structures of the further separator plate 26. In particular, these structures comprise inner cooling fluid channels 41' of the further separator plate 26, in which cooling fluid can be guided.

[0128] Referring first to the outside of the first separator plate 24, the raised areas 50, 52 present there are explained, which in turn have similar functions to the raised areas 50-54 explained previously. Fig. 5 have and provide similar effects.

[0129] A first elevation 50 extends at least in sections in the direction of an adjacent and in Fig. 6 uppermost web 42 of the secondary area 38. Furthermore, the first lift 50 transitions into the outermost web 36' of the distribution area 28. In this respect, the first lift 50 is from Fig. 6 to the first increase 50 from Fig. 4 are at least partially comparable with regard to positioning and extent. However, the first elevation 50 also extends directly and continuously with a further section 50' between the uppermost web 42 and the middle web 42 in Fig. 6. In this respect, it performs essentially the same function as the second bridge 52 of the Fig. 4 and Fig. 5 ready. More precisely, the further section 50' again forms an internal cooling fluid path, which allows fluid inlet and / or outlet into the internal cooling fluid secondary channel 41, which is formed by the central web 42.

[0130] The embodiment from Fig. 6 includes a further increase 52, which is comparable to the third increase 54 of the Fig. 4 and Fig. 5 is trained and positioned and provides a similar effect.

[0131] The raised sections 50, 50' and 52, together with the intervening web sections of the webs 42, enable a curved path for the cooling fluid on its way from the outermost web 36' of the distribution area 28 to the lowest web 42. This results in a main flow axis C, which corresponds to the axis A. Fig. 4 and Fig. 5 functionally corresponds.

[0132] The main flow axis C for lifting runs at least partially at an angle W (schematically indicated) to a main flow axis S' of the secondary region 38. This angle W can be, for example, less than 60° or less than 45°. This enables largely turbulence-free and low-resistance fluid flow between the inner secondary fluid channels 41 and an inner fluid channel of the outermost web 36' of the distribution region 28. The angle W corresponds to the smallest possible intersection angle between this main flow axis C for lifting and the main flow axis S'.

[0133] Referring again to the inner cooling fluid channels 41' of the further separator plate 26, it is shown that at least one of these cooling fluid channels 41', which is described in Fig. 6, which is assigned the corresponding reference numeral, runs opposite the first and second rises 50, 52. In particular, it branches such that individual strands of it are opposite the respective inner cooling fluid auxiliary channels 41. Alternatively, these individual strands can each be considered as an inner cooling fluid channel 41' of the further separator plate 26, wherein these individual strands are fluid-conductingly connected by a further inner cooling fluid channel 41' of the further separator plate 26, which is at least partially opposite the rises 50, 52.

[0134] In Fig. Figure 6 shows that one end of the inner cooling fluid channel 41', or of one of the inner cooling fluid channels 41', is opposite the outermost web 36' of the first separator plate 24. Since this outermost web 36' forms an inner cooling fluid channel, cooling fluid can flow into the inner cooling fluid channel 41' of the second separator plate 26. Additionally, the cooling fluid can also flow along the inner surface along the raised sections 50, 52. In this way, the cooling fluid can be reliably and sufficiently distributed to the cooling fluid channels 41 to ensure effective cooling of the secondary area 38 of the flow field 30.

[0135] Fig. 7 shows one to Fig. Figure 5 shows a comparable embodiment, in which, however, the flow cross-sections of the first to third rises 50-54 are optionally constant and identical to each other. Furthermore, internal channels and, in particular, cooling fluid auxiliary channels 41' of the further separator plate 26 are again shown by means of dashed lines. It can be seen that the webs 42 of the auxiliary area 38 and the cooling fluid auxiliary channels 41 formed therefrom are each opposite internal cooling fluid auxiliary channels 41' of the further separator plate 26. However, in the case shown, these do not extend in such a way that they are also positioned opposite the outermost web 36' of the distribution area 28. Both the cooling fluid auxiliary channels 41 of the separator plate 24 and the cooling fluid auxiliary channels 41' of the further separator plate 26 are supplied with cooling fluid via this outermost web 36' or 36.1'.

[0136] Fig. 8 is a perspective view of the in Fig. Figure 7 shows a section of the bipolar plate 20. It can be seen that the structures on the outer surface of the separator plate 24 are flattened in sections. This occurs in a transition region 60, which is specifically flattened to accommodate a reinforced edge region of a MEA (not shown). The transition region 60 extends transversely to the main flow axis S at least along the entire flow field 30, as shown in Figure 7. Fig. 3 is indicated accordingly. In the example shown, it can in principle be assigned to the distribution area 28. The transition area 60 comprises web and channel sections that transition into the webs 36.1, 42 and channels 40 of the secondary area 38 and the main area 32 of the flow field 30.

[0137] The transition from transition zone 60 to the actual flow field 30, in Fig. The line 80', labelled with 8, can be considered the fluid inlet and / or outlet region of the flow field 30. Alternatively, the line in Fig. 3 Line 80, where, closest to the adjacent through-openings (in other words: on the side facing the adjacent and / or nearest through-openings), both plates 24, 26 have the lowest web height on their outer side, are considered as the fluid inlet and / or outlet area of ​​the flow field 30, even if this line 80 may belong to the transition or distribution area 60, 28.

[0138] Out of Fig. Figure 8 clarifies that the elevations 50, 52, 54 are each positioned within one of the flow field subsidiary channels 41, but at a short distance from the transition region 60. For example, this distance can be less than 5 cm and, in particular, less than 1 cm. The distance can be measured along a main flow axis S' of the subsidiary region 38. This short distance of the elevations 50, 52, 54 from the transition region 60, in turn, allows for cooling of the subsidiary region 38 over a considerable length.

[0139] Furthermore, in Fig. Figure 8 shows that the length L1 of the transition zone 60, measured along the main flow axis S' of the secondary zone 38, is greater than a comparable length L2 of the uplifts 50, 52, 54. This illustrates that the uplifts 50, 52, 54 only form flow obstructions and, in particular, cross-sectional constrictions within the secondary flow channels 41 over correspondingly short lengths. However, it would also be possible that at least one of the uplifts 50, 52, 54 has a length L2 that is equal to or greater than L1, at least in certain sections.

[0140] The increases 50, 52, 54 can only be applied in the transition range 60 (see Fig. 10), exclusively in flow field 30 (see Fig. 5, Fig. 7, Fig. 8, Fig. 11, Fig. 12) or both in the transition zone 60 and in the flow field 30 (see Fig. 4, Fig. 6, Fig. 9) be arranged. In Fig. 6. A lift 50 even extends into the remaining distribution area 28. If the lifts 50, 52, 54 are formed in the flow field 30, more installation space is available overall, which can be divided between the flow space on the outside and the flow space on the inside, i.e. the cooling fluid flow path spanned by the lifts 50, 52, 54, than in the transition area.

[0141] Fig. 9 shows one to Fig. 8 comparable perspective views, which, however, represent the embodiment of the Fig. 4 concerns. In this case, it can be seen that the increases 50, 52, 54 extend at least partially into the transition zone 60. The in Fig. The uppermost first rise 50 transitions into a web section 68, which is described below and which transitions into one of the webs 42 of the secondary area 38. The first rise 50 is connected to the outermost web 36' of the distribution area 28 in such a way that cooling fluid guided on the inside of the outermost web 36' can flow along the inside of the rise 50 and vice versa.

[0142] From the example of Fig. Figure 9 clarifies that the connecting section 45 of the secondary distribution channel 44 divides into several channel sections 66 on the outside of the first separator plate 24 in the transition area and under the overflow of the first lift 50, but not the further lifts 52, 54. These channel sections 66 each transition into one of the flow field secondary channels 41. They are also separated from each other by web sections 68, which transition into the webs 42 of the secondary area 38 of the flow field 30. The web sections 68 are lowered relative to the web surfaces of the webs 42 of the secondary area 38, as they are located in the transition area 60. It would also be possible, in principle, for at least part of the branching or division to occur not in the transition area 60, but in the part of the distribution area 28 further away from the flow field 30.in the x-direction at the level of distribution area 28 (in other words: in the same area along the x-axis and / or the main flow axis S as distribution area 28).

[0143] The Fig. 10 shows one of the Fig. 4 and Fig. 5. A fundamentally comparable partial view in a top view, however, the elevations 50, 52, 54 are arranged in the transition area 60. In contrast, the Fig. 11 a perspective view analogous to Fig. 9. In each of the Fig. 10 and Fig. Figure 11 shows further embodiments of the lifts 50-54. Fig. As mentioned before, 10 shows one of Fig. 5. In principle, an analogous case exists where the flow cross-sections of the uplifts 50-54 decrease with increasing distance from the main area 32 of the flow field 30. However, unlike in Fig. 5 In this case, the flow cross-sections of each lift 50-54 are constant. The differences in flow cross-section between the lifts 50-54 are achieved by differences in a dimension of the lifts 50-54 measured along a main flow axis S'.

[0144] Fig. Figure 11 shows an alternative case in which the respective flow cross-sections are achieved by means of different heights H of the elevations 50-54. The heights H are measured orthogonally to a plane of the separator plate 24. The elevation 50 closest to the main area 32 of the flow field 30 has the greatest H max compared to the other increases of 50, 52.

[0145] Fig. Figure 12 shows another embodiment, which is fundamentally similar to that of the Fig. 4 is formed. However, the channel 40 of the secondary area 38, which is closest to the main area 32 of the flow field 30, not only has one lift 50, but two lifts 50a and 50b arranged one behind the other in the flow direction of the channel 40. The lift 50b can be formed analogously to the lifts 52 and 54, the lift 50a like the lift 50 in Fig. 4. In this way, more cooling fluid can be transported from the outermost web 36.1' of the main area 32 into the channels 40 of the secondary area 38 than in Fig. 4.

[0146] The Fig. Figure 13 shows a cross-sectional view through a bipolar plate 20, which is basically according to the example from Fig. 11 may be formed, but with slightly different proportions. A cutting plane is perpendicular to the planar surfaces of the separator plates 24, 26. The cutting plane runs along axis A. Fig. 11.

[0147] Fig. Figure 13 shows a compressed state of the bipolar plate 20 and / or a state in which its separator plates 24, 26 are firmly and, in particular, metallurgically bonded to one another. Fig. Figure 13 shows the first separator plate 24 as an example, positioned at the top, and the second separator plate 26 as positioned below. The facing inner sides and the facing outer sides of separator plates 24 and 26 are clearly visible.

[0148] The separator plate 24 shows, even though in the underlying section view Fig. 11 not shown separately, a previously explained sealing bead 48 and a limiting element 46, comparable to Fig. 4. Also marked are the secondary channels 40 of the flow field and the ribs 42 in the secondary area 38 of the flow field 30. An outermost rib 36.1' of the main area 32 of the flow field 30 is also marked. Accordingly, the two in Fig. 13 right channels on the outside of the first separator plate, 24 channels 34.1 of the main area 32.

[0149] The cutting plane runs through the raised sections 50, 52, 54. Analogous to Fig. Figure 11 again shows the different heights of these elevations 50, 52, 54 and the associated different depths of the respective flow field auxiliary channels 40. Also marked are the cooling fluid auxiliary channels 41 formed on the inner sides of the webs 42 of the auxiliary area 30.

[0150] Out of Fig. Figure 13 shows that the raised sections 50, 52, 54 increase the distance D, measured perpendicular to the plane E of the planar surface, between the inner surfaces of the separator plates 24, 26. This applies in particular to the distance shown in the Fig.13. The leftmost flow field auxiliary channel 40 of the first separator plate 24, where this separator plate 24 rests on the further separator plate 26. Due to their increased distance D, the raised sections 50, 52, 54 each define internal cooling fluid paths in order to guide cooling fluid internally to or from each of the cooling fluid auxiliary channels 41 in the manner described above.

[0151] By way of example only, the separator plate 26 has a largely comparable secondary area 38 on its outer side, in particular comprising analogously arranged and dimensioned raised sections 50, 52, 54. However, this is not mandatory. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2016 107 302 U1

[0006] DE 20 2020 106 459 U1

[0030]

Claims

[1] Separator plate (24, 26) for an electrochemical system comprising: - at least one first through-hole (22a) for passing a first reaction fluid through the separator plate (24, 26), at least one second through-hole (22b) for passing a second reaction fluid through the separator plate (24, 26) and at least one third through-hole (22c) for passing a cooling fluid through the separator plate (24, 26); - on an outer side of the separator plate (24, 26): at least one distribution area (28), one flow field (30) and at least one distribution side channel (44); wherein the distribution area (28) fluidly connects the first through-opening (22a) and a main area (32) of the flow field (30); wherein the distribution side channel (44): - connects the first through-opening (22a) and a secondary area (38) of the flow field (30) in a fluid-conducting manner, and - extends at least section by section along a circumferential section of the first and / or the second and / or the third passage opening (22a-c) facing away from the distribution area (28); wherein the secondary area (38) has a plurality of flow field subsidiary channels (40) and webs (42) formed between each pair of flow field subsidiary channels (40), wherein the webs (42) each form a complementary shaped cooling fluid side channel (41) on the inside of the separator plate (24, 26), wherein the distribution side channel (44) and / or the flow field side channel (40) has at least one sectional elevation (50, 52, 54) of a channel bottom (43), and wherein the at least one elevation (50, 52, 54) on the inside of the separator plate (24, 26) forms a section of a fluid connection between at least one of the cooling fluid side channels (41) and the third through-opening (22c). [2] Separator plate (24, 26) according to claim 1, wherein the at least one elevation (50, 52, 54) is formed in one of the flow field auxiliary channels (40) and the distance of the elevation (50, 52, 54) to a nearest fluid inlet and / or outlet area of ​​the flow field (30) measured along a main flow axis (S') of this flow field auxiliary channel (40) is at most 5 cm, in particular at most 2 cm, in particular at most 1 cm, and / or at most 10 %, in particular at most 6 % of a total length of the flow field auxiliary channel (40). [3] Separator plate (24, 26) according to claim 1 or 2, wherein a second distribution side channel (49) is formed which - connects the first through-opening (22a) and the secondary area (38) of the flow field (30) in a fluid-conducting manner, and - extends at least in sections along a circumferential section of the second and / or third passage opening (22c) facing the distribution area (28). [4] Separator plate (24, 26) according to claim 3, wherein the at least one elevation (50, 52, 54) has a length in the direction of extension of a flow field secondary channel (40) of at most 5% of the length of the shortest distribution secondary channel (44, 49) to the boundary of the flow field (30) or the flow field secondary channel (40); and / or wherein the at least one elevation (50, 52, 54) extends with a length in the direction of extension of a flow field secondary channel (40) of at most 2 cm, in particular at most 1 cm or at most 0.5 cm, along a main flow axis (S') of the flow field secondary channel (40). [5] Separator plate (24, 26) according to one of the preceding claims, wherein an average height (H) of the at least one elevation (50, 52, 54) measured perpendicular to the plane of the planar surface (E) is at most 80%, at most 60%, in particular at most 50% of a maximum height (H) measured perpendicular to the plane of the planar surface (E). max) has a structure that limits that of distribution side channel (44) or flow field side channel (40) in which at least one elevation (50, 52, 54) is formed. [6] Separator plate (24, 26) according to one of the preceding claims, wherein the at least one raised section (50, 52, 54) is formed in one of the flow field side channels (40) and connects two webs (42) bounding the flow field side channel (40) together. [7] Separator plate (24, 26) according to one of the preceding claims, wherein the raised section (50, 52, 54) is formed in one of the flow field subsidiary channels (40) and connects a web (42) bounding this flow field subsidiary channel (40) and a structure (36.1') bounding the main area (32) of the flow field, on the inside of which cooling fluid can be guided. [8] Separator plate (24, 26) according to one of the preceding claims, wherein the secondary area comprises at least three webs and at least two flow field secondary channels (40), which are each at least partially bounded by two adjacent of these webs, wherein the two adjacent webs are connected to each other by at least one partial elevation (50, 52, 54) of the channel bottom of the flow field secondary channel (40) bounded thereby. [9] Separator plate (24, 26) according to claim 8, wherein the respective at least one elevations (50, 52, 54) within the flow field side channels (40) are distributed along a common axis which is orthogonal to a main flow axis (S') of the flow field side channels (40). [10] Separator plate (24, 26) according to claim 8, wherein at least one of the elevations (50, 52, 54) within the secondary flow channels (40) has an elevation main flow axis (C) which runs at an angle (W) of less than 60° or less than 45° to a main flow axis (S') of the secondary flow channels (40). [11] Separator plate (24, 26) according to claim 9 or 10, wherein an inner flow cross-section of one of the elevations (50, 52, 54) which is further apart from the main area (32) is smaller than that of the corresponding other elevation (50, 52, 54). [12] Separator plate (24, 26) according to one of the preceding claims, wherein the separator plate (24, 26) comprises a continuous lowered transition area (60) which includes end sections of the distribution bypass channel (44) and the distribution area (28) transitioning into the flow field (30), wherein in the flow field (30) the mean channel height h1 measured perpendicular to the plane of the planar surface (E) is and in the transition area (60) the maximum channel height h measured perpendicular to the plane of the planar surface (E) is max is, where h max ≤ 0.95·h1. [13] Separator plate (24, 26) according to claim 12, wherein the at least one elevation (50, 52, 54) is formed in a section of the distribution side channel (44) which extends into the transition area (60). [14] Separator plate (24, 26) according to claim 13, wherein the distribution side channel (40) branches into several channel sections (66) in the transition area (60), each separated by bridge sections (68), wherein the channel sections (66) transition into the flow field side channels (40) and the bridge sections (68) transition into the bridges (42) of the side area (38), wherein at least one elevation (50, 52, 54) is formed at least sectionally in one of the channel sections (66) and is connected to a structure (36') limiting the distribution area (28), on the inside of which cooling fluid can be guided. [15] Separator plate (24, 26) according to one of claims 12 to 14, wherein a length (L2) measured along a main flow axis (S') of a flow field side channel (40) of at least one lift (50, 52, 54) is less than a length (L1) of the transition area (60) measured along this main flow axis (S'). [16] Separator plate (24, 26) according to one of the preceding claims, wherein the separator plate (24, 26) has at least two sectional elevations (50, 50') of a channel bottom (43) arranged one after the other in the direction of the flow channel in at least one continuous flow channel with a distribution side channel (44) and a flow field side channel (40) adjoining the latter. [17] Bipolar plate (20) for an electrochemical system comprising a first separator plate (24) according to any one of claims 1 to 16 and a second separator plate (26), wherein the inner sides of the first and second separator plates (24, 26) are facing each other, so that the cooling fluid can be guided between them.

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