Separator plate for an electrochemical system and associated arrangement comprising a plurality of separator plates

Abstract

Separator plate (2) for an electrochemical system (1), comprising a first single plate (2a) and a second single plate (2b) connected to the first single plate (2a), wherein the first single plate (2a) has molded-in, adjacent, first channels (30) for media guidance on a side facing away from the second single plate (2b), which are separated from each other by first webs (32) formed between the first channels (30), wherein, on one of the sides of the first single plate (2a) facing the second single plate (2b), the first channels (30) form first elevations (34) and the first webs (32) form first grooves (36), wherein the second single plate (2b) has molded-in, parallel second channels (40) for media guidance on a side facing away from the first single plate (2a), which are separated from each other by second webs (42) formed between the second channels (40), wherein, on the side of the second single plate (2b) facing the first single plate (2a), the second channels (40) form second raised areas (44) and the second webs (42) form second grooves (46), wherein the first single plate (2a) is arranged relative to the second single plate (2b) such that the second elevations (44) project into the first grooves (36) at intervals and the first elevations (34) project into the second grooves (46) at intervals, characterized by the fact that at least one of the first grooves (36) and / or at least one of the second grooves (46) is formed in a section along its elongate extent transverse to its elongate extent in a stepped manner with a region (37, 47) of reduced groove depth - forming a support structure - wherein the region (37, 47) with reduced groove depth touches the opposite elevation (44, 34) of the other single plate for supporting the first single plate (2a) on the second single plate (2b).

Description

[0001] The disclosure relates to a separator plate for an electrochemical system and to an arrangement comprising at least one such separator plate.

[0002] Common electrochemical systems, such as fuel cell systems, electrochemical compressor systems, redox flow batteries, and electrolyzers, typically comprise a multitude of separator plates arranged in a stack, such that each pair of adjacent separator plates encloses an electrochemical cell. The separator plates usually consist of two individual plates connected along their back surfaces facing away from the electrochemical cells. The separator plates can serve, for example, to electrically connect the electrodes of individual electrochemical cells (e.g., fuel cells) and / or to electrically connect adjacent cells (series connection of the cells).

[0003] The individual plates of the separator plates can have channel structures for supplying the cells with one or more media and / or for removing media. In the case of fuel cells, the media can be, for example, fuels (e.g., hydrogen or methanol), reaction gases (e.g., air or oxygen), or a coolant as supplied media, and reaction products and heated coolant as discharged media. Furthermore, the separator plates can serve to dissipate the waste heat generated in the electrochemical cell, such as that produced during the conversion of electrical or chemical energy in a fuel cell, and can be designed to seal the various media and / or cooling channels from each other and / or to the outside. In fuel cells, the reaction media, i.e., the reaction gases, are typically located on the surfaces of the individual plates facing away from each other.Fuel and reaction gases are guided through the bipolar plates, while the coolant is guided between the individual plates. The bipolar plates typically each have at least one or more through-holes. Through these through-holes, the media and / or the reaction products can be guided to the electrochemical cells bounded by adjacent separator plates of the stack, or into the cavity formed by the individual plates of the separator plate, or discharged from the cells or the cavity. The electrochemical cells, particularly of a fuel cell, can each comprise, for example, a membrane electrode assembly (MEA) with a polymer electrolyte membrane (PEM) and electrodes. The MEAs can also have one or more gas diffusion layers (GDLs), which are typically oriented towards the separator plates, particularly those of fuel cell systems, and are, for example,The membranes are formed as carbon fleece. In a typical fuel cell, hydrogen is supplied to one side of the anode and oxygen is supplied to the other side of the cathode to produce water. Protons produced during the oxidation of the hydrogen pass from the anode through the membrane energy exchanger (MEA) to the cathode, where they react with the oxygen and electrons to form water. The fuel cell membrane is electrically insulating and prevents a short circuit between the anode and cathode. The electrons are then separately supplied from the anode to the cathode, thus making the electrical current usable.

[0004] In application areas of electrochemical systems, especially in automotive sectors or in the field of aviation, high demands are placed on the installation space required by the electrochemical system and on the weight of the system.

[0005] The object of the invention is therefore to propose an improved separator plate and / or an improved arrangement comprising a plurality of separator plates, in particular in that a reduced installation space of the separator plate and / or the arrangement is achieved and / or a reduced weight of the coolant carried in the separator plate. Additionally or alternatively, it may be an object to reduce the coolant requirement.

[0006] This problem is solved according to the invention by the separator plate according to claim 1 and / or an arrangement according to the dependent claim. Further developments are the subject of the dependent claims and the following description.

[0007] The proposed separator plate for an electrochemical system comprises a first single plate and a second single plate connected to the first single plate.

[0008] The first single plate has molded-in, parallel channels for media guidance on one side facing away from the second single plate, which are separated from each other by first webs formed between the first channels.

[0009] On the side of the first single plate facing the second single plate, the first channels form the first raised areas and the first ribs form the first grooves.

[0010] The second single plate has molded-in, parallel second channels for media guidance on one side facing away from the first single plate, which are separated from each other by second webs formed between the second channels.

[0011] On the side of the second single plate facing the first single plate, the second channels form second raised areas and the second ribs form second grooves.

[0012] The first single plate is arranged in such a way as to the second single plate that the second raised sections project into the first grooves at a distance from each other, and the first raised sections project into the second grooves at a distance from each other.

[0013] At least one of the first grooves and / or at least one of the second grooves is / is in a section along its elongated extent transverse to its elongated extent stepped with a region of reduced groove depth - forming a support structure - wherein the region with reduced groove depth touches the opposite elevation of the other single plate to support the first single plate on the second single plate.

[0014] The support structure therefore corresponds to the area of ​​reduced groove depth. The reduced groove depth is particularly evident when compared to a maximum or typical, and thus nominal, groove depth.

[0015] The longitudinal extent of the first groove corresponds in particular to the longitudinal extent of the first channels and / or second channels. The longitudinal extent of the second groove corresponds to the longitudinal extent of the first and / or second channels. In the following description, unless explicitly stated otherwise, the described features apply to the support structures of the first individual plate and / or the second individual plate, respectively.

[0016] The proposed arrangement allows, in particular, the formation of a continuous cavity between the first and second individual plates. When the separator plate is arranged in an electrochemical system, coolant can be introduced into this cavity to cool the individual plates.

[0017] The proposed separator plate design allows for advantageous nesting of the individual plates, resulting in a reduced component height. Deformation of the separator plate during operation in an electrochemical system can be reduced or prevented by partially supporting the individual plates against each other via support structures. Furthermore, the volume of the cavity between the individual plates can be reduced, leading to a reduction in coolant requirements when the separator plates are used in an electrochemical system. This reduction in coolant consumption can also reduce the overall weight of the electrochemical system.

[0018] Nested arrangements already exist in the prior art. However, the known arrangements are nested in such a way that web areas are not, or insufficiently, cooled, leading to local temperature overloads at the MEA. This can cause the electrochemical system to fail.

[0019] In one embodiment, a multitude of support structures can be formed in one of the first grooves and / or in one of the second grooves. The support structures within a groove can be spaced apart from each other.

[0020] A plurality of first grooves and / or a plurality of second grooves can each form at least one such support structure. In particular, a plurality of first grooves and / or a plurality of second grooves can each form a plurality of such support structures. The support structures can improve the stability of the separator plate and simultaneously enable surface cooling.

[0021] A contact plane in which the area with less depth touches the opposite elevation of the other single plate to support the first single plate on the second single plate can be inclined by a maximum of 15°, preferably by a maximum of 10°, and in particular by a maximum of 5° to the plane of the planar surface.

[0022] In one embodiment, the first channels can run parallel to each other, at least partially, preferably completely. Additionally or alternatively, the first channels can run in a wavy pattern, particularly a uniformly wavy pattern, at least partially or completely. Additionally or alternatively, the second channels can run parallel to each other, at least partially, preferably completely. Additionally or alternatively, the second channels can run in a wavy pattern, particularly a uniformly wavy pattern, at least partially or completely. The first channels can run parallel to the second channels, at least partially, preferably completely.

[0023] In one embodiment, the first and second channels and the first and second webs can have a straight course. Alternatively, the first and second channels and the first and second webs can have a wavy or partially curved course.

[0024] In one version, the first single plate can be identical to the second single plate, for example to reduce manufacturing costs.

[0025] The first channels and the second channels can have main extension directions which are aligned parallel to the respective plane of the plan and parallel to each other.

[0026] The plane of the plan can also be referred to as the plate plane in this case.

[0027] In one embodiment, the width of the support structure, measured transversely to the longitudinal extent of the respective groove, can decrease and increase again along the length of the support structure. Alternatively, the width of the support structure, measured transversely to the longitudinal extent of the respective groove, can remain constant in certain sections along the length of the support structure.

[0028] A minimum support structure width can be at least 0.3, 0.4, or 0.5 times the groove width. A maximum support structure width can be at most 0.9, 0.8, or 0.7 times the groove width. The groove width can be measured at the bottom of the groove. Alternatively, the groove width—for all groove widths to be compared—can be measured in the area of ​​the inflection points of the flanks between the grooves and adjacent raised sections, or at half the height of a flank section that runs straight when considering the grooves / channels and raised sections / webs in cross-section, in which the inflection points lie or which is bounded by two inflection points.

[0029] The minimum length of the support structure can be at least 0.3, 0.4, or 0.5 times the groove width. The maximum length of the support structure can be at most 5, 3, or 2 times the groove width. Both the groove width and the length of the support structure can be measured at the bottom of the groove. Alternatively, the groove widths and lengths of the support structure—for all grooves and support structures, respectively—can be measured at the inflection points of the flanks between the grooves and adjacent raised sections, or at the inflection points in the ascent and descent of the support structures. Measurements can also be taken at mid-height of a straight flank section—when considering the grooves and raised sections in cross-section or the support structures in longitudinal section—where the inflection points lie or are bounded by two inflection points.

[0030] The support structures arranged in parallel grooves of the first and / or second individual plate can be arranged such that at least some of the support structures are arranged in at least one row transversely to the longitudinal groove direction. All or some of the support structures in such a row arranged transversely to the longitudinal groove direction can be of the same type and / or have different shapes. Additionally or alternatively, all or some of the support structures in a row along a groove direction can be of the same type and / or have different shapes.

[0031] In one embodiment, the support structures of the first groove and / or the second groove can alternately originate from a first and a second groove flank that define the respective groove along the elongated groove path. The support structures are spaced apart from the other groove flank.

[0032] In a groove, the support structures can all originate from the same groove flank that defines the respective groove along its length. In adjacent grooves with support structures, the support structures in one groove can originate from the same groove flank, while in one or more further grooves, for example, an adjacent groove, the support structures can all originate from the other groove flank. Grooves without support structures can be arranged between grooves with support structures.

[0033] The arrangement and shape of the support structures can be advantageous in order to influence the flow behavior of the cooling medium, in particular to guide a cooling medium and / or counteract turbulence.

[0034] The first and / or second single plate can have a first and a second, and in particular a third, area, wherein the support structures in the first area are arranged offset from each other, the support structures in the second area are arranged in rows perpendicular to the channel direction, and in particular the support structures in the third area are arranged offset from each other.

[0035] The first, second, and third sections can, for example, be arranged sequentially along the main flow direction. As described above regarding the shape of the support structures, the support structures can additionally or alternatively be arranged in a pattern that can guide the coolant, for example, from an edge region of the flow field towards its center.

[0036] The areas of reduced groove depth that form the support structures and are distributed across the flow field can have different groove depths. In particular, two or more areas of reduced groove depth can be formed in which support structures of the same groove depth are arranged.

[0037] The first and / or the second individual plate can have a first and a second, and in particular a third, area, wherein the support structures in the first area have a region of reduced groove depth with a first depth, and the support structures in the second area have a region of reduced groove depth with a second depth. The first depth can be different from the second depth. Additionally, the support structures in the third area can have a region of reduced groove depth with a third depth, and the third depth can be different from the first and / or the second depth.

[0038] In particular, a centrally located area can be designed such that, within this centrally located area, the areas of reduced groove depth differ even more significantly in depth compared to the areas of nominal groove depth, meaning they are very shallow. This allows the raised sections of the other individual layer to penetrate less deeply into these groove sections, resulting in a locally thicker separator plate overall. This at least partially or completely compensates for any deflection of the end plate in this centrally located area.

[0039] In one embodiment, both individual plates, i.e., the first and the second individual plate, can have support structures. The support structures of the first individual plate can be arranged offset from the support structures of the second individual plate in an orthogonal projection.

[0040] Each individual plate can include at least two through-holes for guiding a fluid, a flow field, and two transition areas.

[0041] A first transition zone can be a distribution zone and can be arranged between a first through-opening and the flow field. A second transition zone can be arranged between the flow field and a second through-opening and can be a collection zone. The transition zones can fluidically connect the through-openings to the flow field. The flow field can be an electrochemically active zone. The support structures can be arranged in the active zone of the first and / or second individual plate, and in particular, only in the active zone.

[0042] The first channels and the second channels can be arranged in the electrochemically active area of ​​the separator plate, with the first ribs and the second ribs forming contact surfaces for a membrane electrode unit, in particular its gas diffusion layer.

[0043] In this context, the terms "electrochemically active area" or "active area" can be used to describe the area of ​​the individual plate that faces an electrochemically active area of ​​the MEA when the individual plate is arranged in an electrochemical system. The membrane of the MEA extends, in particular, at least over the electrochemically active area of ​​the adjacent separator plates and enables proton transfer across or through the membrane. The actual electrochemically active area may be bounded by the edge section of the MEA.

[0044] In one embodiment, the height of the separator plate, measured perpendicular to a flat surface of the separator plate, can be less than the sum of the material thicknesses of the two individual plates and twice the maximum channel depth. The maximum channel depth corresponds to the maximum height of a raised section and also the maximum depth of a groove, i.e., the nominal groove depth in the individual plate where this maximum channel depth is greater than in the other individual plate. However, the maximum channel depth can also be identical in both individual layers.

[0045] The first single plate and the second single plate can each have a plate body made of metal, wherein the first channels and the second channels are formed, in particular embossed, into the respective plate body.

[0046] The separator plate can be rotationally symmetrical by 180°, at least in sections, within its plane. For example, the through-openings and transition zones can be rotationally symmetrical, while the flow field areas are not. In an electrochemical system, this allows for an advantageous mutual reinforcement of the effects of the individual structures without requiring the use of identical components for the first and second individual plates.

[0047] The present invention further relates to an arrangement for an electrochemical system comprising a plurality of separator plates as described above. Preferably, MEAs and optionally GDLs are arranged between adjacent, i.e., mutually nearest, separator plates.

[0048] Adjacent separator plates can be rotated 180° relative to each other in the plane of one of the separator plates. With a suitable arrangement of the structures, a 180° rotation in the plane of one separator plate, for example, of each separator plate arranged alternately with a non-rotated separator plate, results in an overall arrangement in which, in orthogonal projection of the webs and channels or grooves and projections of two adjacent separator plates into a common plane, these structures are offset. Likewise, the support structures can be arranged in such a non-rotationally symmetrical manner.

[0049] Some or all of the separator plates can be configured such that, in an orthogonal projection of a first separator plate onto an adjacent separator plate, support structures of the first separator plate are arranged, at least in certain areas, in the same areas of the adjacent separator plate where support structures of the second separator plate are located. Additionally or alternatively, some or all of the separator plates can be configured such that, in an orthogonal projection of the support structures of a first separator plate onto an adjacent separator plate, support structures of the first separator plate are arranged, at least in certain areas, offset from support structures of the adjacent separator plate. This can allow the membrane to be subjected to no or reduced shear stress between the webs.

[0050] The arrangement can also include, in particular, adjacent separator plates which, in an orthogonal projection, have support structures that are partially offset from each other and have support structures that overlap in some areas.

[0051] In one embodiment of the arrangement, at least one adjacent separator plate that does not have such support structures can be arranged next to a first separator plate having support structures.

[0052] Adjacent to a first separator plate having support structures, at least one neighboring separator plate can be arranged which – in an orthogonal projection of the support structures of the first separator plate onto the neighboring separator plate – has no support structures, at least in the area of ​​the support structures of the first separator plate. Likewise, the separator plates at the ends of a stacked arrangement, for example, only the last separator plate, can be designed with support structures, while the separator plates located centrally in the arrangement can be designed without support structures.

[0053] Exemplary embodiments of the proposed separator plate and the proposed arrangement are shown in the figures and are explained in more detail below. The figures show: Fig. 1. Schematic representation in a perspective view of an electrochemical system with a plurality of separator plates arranged in a stack; Fig. 2 schematically in a perspective view two separator plates of the system according to Fig. 1 with a membrane electrode assembly (MEA) arranged between the separator plates; Fig. 3 schematically a cross-section through a stack of plates of a system according to the type of system according to Fig. 1; Fig. 4A schematically a view of a section of an active area of ​​a separator plate of a system according to the type of system according to Fig. 1; Fig. 4B schematically shows a section through the Fig. 4A section shown along the section line BB; Fig. 4C schematically shows a section through the in Fig. 4A section shown along the section line CC; Fig. 4D schematically a cross-section through a Fig. 4A section shown along the cutting line DD; Fig. 4E schematically a perspective view of the in Fig. 4A section shown in rotated view; Fig. 5A schematically a view of a section of an active area of ​​a separator plate of a system according to the type of system according to Fig. 1; Fig. 5B schematically a cross-section through the in Fig. 5A section shown along the section line EE; Fig. 5C schematically shows a section through the in Fig. 5A section shown along the section line FF; Fig. 5D schematically a cross-section through a Fig. 5A section shown along the section line GG; Fig. 6 schematically a section through an arrangement for an electrochemical system with a section of a plate stack of a system according to the type of system according to Fig. 1; Fig. 7 schematically a section through another arrangement for an electrochemical system with a section of a plate stack of a system according to the type of system Fig. 1; Fig. 8 schematically a section through another arrangement for an electrochemical system with a section of a plate stack of a system according to the type of system Fig. 1; and Fig. 9 schematically a top view of a section of an active area of ​​a separator plate of a system according to the type of system according to Fig. 1.

[0054] Here and in the following, recurring features in various figures are designated with the same or similar reference symbols.

[0055] Fig. Figure 1 shows an electrochemical system 1 with a plurality of identical metallic separator plates 2 arranged in a stack 6 and stacked along a z-direction 7. The separator plates 2 of the stack 6 are clamped between two end plates 3, 4. The z-direction 7 is also called the stacking direction. In this example, the system 1 is a fuel cell stack. Each pair of adjacent separator plates 2 of the stack encloses an electrochemical cell, which serves, for example, to convert chemical energy into electrical energy. To form the electrochemical cells of the system 1, a membrane electrode assembly (MEA) 10 is arranged between each pair of adjacent separator plates 2 of the stack (see, for example, Figure 1). Fig. 2 or Fig. 6 to 8). 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, in Fig. 1 and 2 are not shown, but for example in the Fig. 6 to 8 are visible.

[0056] In alternative embodiments, system 1 can also be configured as an electrolyzer, an electrochemical compressor, or a redox flow battery. Separator plates can also be used in these electrochemical systems. The design of these separator plates can then correspond to the design of separator plates 2 described in more detail here, even though the media guided on or through the separator plate in an electrolyzer, an electrochemical compressor, or a redox flow battery may differ from the media used in a fuel cell system.

[0057] The z-axis 7, together with the x-axis 8 and y-axis 9, defines a right-handed Cartesian coordinate system. The separator plates 2 each define a plate plane, with the plate planes of the individual plates 2a and 2b being aligned parallel to the xy-plane and thus perpendicular to the stacking direction and the z-axis 7, respectively. 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 coolants such as water and / or glycol.

[0058] Fig. Figure 2 shows, in perspective, two adjacent separator plates 2 of an electrochemical system of the type of system 1. Fig. 1 and a membrane electrode unit (MEA) 10 arranged between these adjacent separator plates 2, known from the prior art, wherein the MEA 10 is in Fig. 2 is largely obscured by the separator plate 2 facing the viewer. The separator plate 2 is formed from two individual plates 2a, 2b joined together (see e.g. Fig. 3), of which in Fig. 2. Only the first individual plate 2a, facing the viewer, is visible, concealing the second individual plate 2b. The individual plates 2a and 2b can each be made of a single metal sheet, e.g., a stainless steel sheet. The individual plates 2a and 2b can be welded together, e.g., by laser welding. On the one hand, the individual plates 2a and 2b can be tightly welded along and spaced from their outer edges, or at least along the inner edge of a portion of the through-openings, with sealing seams, particularly outside and / or inside the perimeter groove 12d. Further weld seams are possible.

[0059] The individual plates 2a, 2b have aligned through-openings that form through-openings 11a-c of the separator plate 2. When a plurality of separator plates of the type separator plate 2 are stacked, the through-openings 11a-c form conduits 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 connection with one of the ports or media connections 5 in the end plate 4 of system 1. For example, coolant can be introduced into or discharged from the stack 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 6 of system 1 with fuel and reaction gas, as well as to discharge the reaction products from the stack. The media-carrying through-openings 11a-11c are essentially parallel to the plane of the plate.

[0060] To seal the through-openings 11a-c against the interior of the stack 6 and against the environment, the first individual plates 2a each have sealing arrangements in the form of sealing beads 12a-c, which are arranged around the through-openings 11a-c and which completely enclose the through-openings 11a-c. The second individual plates 2b have, on the side visible to the observer, Fig. On the opposite side of each individual plate, two corresponding sealing beads are provided for sealing the through-openings 11a-c (not shown). Alternatively, elastomer seals can also be used.

[0061] In an electrochemically active area 18, the first individual plates 2a exhibit the following characteristics towards the observer: Fig. On the outer side facing 2, a flow field 17 with structures for guiding a reaction medium along the outer side of the single plate 2a is created. These structures are in Fig. 2 is given by a multitude of footbridges 32, 42 and channels 30, 40 running between the footbridges 32, 42 and bounded by the footbridges 32, 42. At the viewer's Fig. On the outer surface of the separator plates 2 facing the surface, the first individual plates 2a each have a distribution and collection area 20. Distribution or collection areas 20 each comprise structures designed to distribute a medium introduced into the distribution area 20 from one of the first of the two through-openings 11b across the active area 18, or to collect or concentrate a medium flowing from the active area 18 towards the second of the through-openings 11b. The fluid guide structures 29 of both distribution or collection areas 20 are arranged in Fig. Two channels are also given, running through bridges and between the bridges and bounded by the bridges. For simplicity, only the distribution area 20 is discussed below; the corresponding statements can equally apply to a collection area 20.

[0062] The sealing beads 12a-12c have feedthroughs 13a-13c which allow passage of medium between the associated through-openings 12a-12c and the distribution area 20 on a gas side or in the interior of the separator plate 2.

[0063] The first individual plates 2a each have a further sealing arrangement in the form of a perimeter bead 12d, which surrounds the flow field 17 of the active area 18, the distribution and collection areas 20, and the through-openings 11b, 11c, and seals them against the through-opening 11a, i.e., against the coolant circuit, and against the environment of the system 1. The second individual plates 2b each comprise corresponding perimeter beads. The structures of the active area 18, the distribution structures of the distribution and collection areas 20, and the sealing beads 12a-d are each formed integrally with the individual plates 2a and molded into the individual plates 2a or 2b, e.g., in an embossing or deep-drawing process or by means of hydroforming.

[0064] The separator plate 2 is formed from two materially bonded individual plates, namely individual plates 2a, 2b (see e.g. Fig. 4 to 8), of which in Fig. 2. Only the first individual plate 2a, facing the viewer, is visible, concealing the second individual plate. The individual plates can each be formed from a shaped metal sheet, e.g., from a stamped or deep-drawn stainless steel sheet. This metal sheet can, for example, have a thickness of at most 150 µm, preferably at most 100 µm, preferably at most 90 µm, and particularly preferably at most 80 µm. The individual plates can be welded together, for example, by laser welding.

[0065] The first individual plate 2a has, on its side facing away from the second individual plate 2b, molded-in, parallel channels 30 for media guidance, which are separated from each other by first webs 32 formed between them. On one side of the first individual plate 2a facing the second individual plate 2b, the first channels 30 form first raised areas 34 and the first webs 32 form first grooves 36. The second individual plate 2b has, on its side facing away from the first individual plate 2a, molded-in, parallel second channels 40 for media guidance, which are separated from each other by second webs 42 formed between them. On one side of the second individual plate 2b facing the first individual plate 2a, the second channels 40 form second raised areas 44 and the second webs 42 form second grooves 46.The first single plate 2a is arranged relative to the second single plate 2b such that the second projections 44 extend into the first grooves 36 at intervals, and the first projections 34 extend into the second grooves 46 at intervals. The nested structure is particularly evident in the cross-sectional views of the... Fig. 4B-4D, 5B - 5D, 6, 7 and 8 are clearly visible.

[0066] The Fig. Figure 3 schematically shows a section through a portion of the stack of plates 6 of system 1. Fig. 1, where the cutting plane is aligned in the z-direction and thus perpendicular to the plate planes of the separator plates 2. The cutting plane runs in the Fig. 3 along a bent cut, along the cutting line AA in Fig. 2. It should be noted that the separator plates of the Fig. Figure 3 is schematic and exemplary and serves to illustrate, in particular the different positions and areas, the structure of the electrochemical system. The nesting of the individual plates 2a, 2b, however, is shown in Fig. 3 not apparent.

[0067] Cooling channels are arranged in the cavity 19 between adjacent individual plates 2a, 2b. In the active area 18, the two individual plates 2a, 2b rest against each other in a contact area 24. The individual plates 2a and 2b may be connected to each other there.

[0068] Between adjacent individual plates 2 of the stack, a membrane electrode assembly (MEA) 10, known from the prior art, is arranged. The MEA 10 typically comprises a membrane 14, e.g., an electrolyte membrane, and an edge section 15 connected to the membrane 14. For example, the edge section 15 can be bonded to the membrane 14 by means of an adhesive bond or by lamination.

[0069] The term "electrochemically active area" is used here to refer to the area of ​​the individual plate 2a, 2b that faces an electrochemically active area of ​​the MEA 10 when the individual plate 2a, 2b is arranged in an electrochemical system. The membrane of the MEA 10 extends at least over the active area 18 of the adjacent separator plates 2 and enables proton transfer across or through the membrane 14. The actual active area 18 is bounded by the edge section 15 of the MEA. Thus, the membrane does not extend into the distribution or collection area 20. The edge section 15 of the MEA 10 serves to position, secure, and seal the membrane between the adjacent separator plates 2.

[0070] The edge section 15 covers the distribution or collection area 20 of the adjacent separator plates 2. The edge section 15 can also extend outwards beyond the perimeter groove 12d and abut or project beyond the outer edge area of ​​the individual plates 2a, 2b (see figure). Fig. 2).

[0071] Furthermore, additional gas diffusion layers 16 can be arranged in the active area 18. The gas diffusion layers 16 allow the flow of gas to the membrane 14 over as large an area of ​​the membrane surface as possible, thus improving proton transfer across the membrane. The gas diffusion layers 16 can, for example, be arranged on both sides of the membrane 14, at least in the active area 18, between the adjacent separator plates 2. The gas diffusion layers 16 can, for example, be formed from or comprise a nonwoven fabric.

[0072] Fig. Figure 4A shows a section of an active area 18 of a separator plate 2 of a system according to Fig. 1. In the top view of the first individual plate 2a shown, channels 40, webs 42, and areas 37 of reduced groove depth of the second individual plate 2b are visible. The first channels 30 and the second channels 40 run straight and parallel to each other. The areas of reduced groove depth form support structures 60, of which, for clarity, only some are labeled. Several support structures 60 are arranged within the longitudinal extent of a groove 46, originating alternately from one of the two lateral flanks bounding the groove along the longitudinal groove extent. In the top view shown, the support structures 60 all have the shape of a longitudinally sectioned oval. In other embodiments, the support structures may have a different shape. For example, the shape of the support structures 60 of a separator plate 2 may vary along or transversely to the groove extent.

[0073] The support structures 60 are arranged in rows perpendicular to the longitudinal groove. The support structures 60 of such a transverse row all originate from the same side of the flank bounding the groove.

[0074] Fig. 4B shows a section of cut BB (as in Fig. 4A shown) through the separator plate section of the Fig. 4A. The first single plate 2a is arranged on the second single plate 2b. This forms the cavity 19 for receiving a coolant. As described above, the first single plate 2a has channels 30 and webs 32 defining the channels 30 on the side facing away from the second single plate 2b. Similarly, the second single plate 2b has channels 40 and webs 42 defining the channels 40 on the side facing away from the first single plate 2a. The areas of reduced groove depth, which form the support structures 60, are visible in the second single plate 2b. A channel 40 is arranged between each of the support structures 60. Section BB runs approximately through the middle of the support structures 60, so that the support structures are shown in the area of ​​their greatest lateral extent. In contact areas 24, the first single plate 2a rests on the second single plate 2b.More precisely, the increase 34 in contact areas 24 lies on area 47 compared to areas with nominal height H. N0 reduced groove depth H N1 on.

[0075] Fig. 4C shows a section of cut CC (as in Fig. 4A shown) through the separator plate section of the Fig. 4A. Section CC does not pass through support structures. The first single plate 2a is spaced apart from the second single plate 2b. In this section, the single plates 2a and 2b do not touch.

[0076] Fig. 4D shows a section of cut DD (as in Fig. 4A shown) through the separator plate section of the Fig. 4A. The section passes through support structures 60, which, compared to those of the Fig. 4B originate from the opposite flank side of the respective groove 46. The support structures are embossed in the second individual plate 2b. The first individual plate 2a also lacks support structures 60. The webs 42 have areas of nominal height H N0 also areas with reduced height H N2 , namely where the support structures 60 are located. In the Fig. In the 4D representation, for example, the second area is the reduced height H. N2 greater than the reduced height H N1 in Fig. In the first area shown in 4B, for example, it is therefore less reduced. As a result, the raised sections of the other single layer penetrate more deeply into these groove sections, resulting in an overall locally thinner separator plate.

[0077] For example, the in Fig. 4D displayed area of ​​lesser reduced depth H N2Advantageously arranged in a peripheral area of ​​the separator plate, while the overall thicker area with a more significantly reduced depth H N1 out of Fig. 4B can advantageously be arranged in a central area of ​​the separator plate. This allows end plate deflection in this centrally arranged area to be at least partially or completely compensated.

[0078] Fig. 4E shows the section of the in Fig. Figure 4A shows the separator plate 2 in a rotated perspective view. In the section shown, the support structures 60 are spaced at uniform intervals. The support structures 60 of the example shown have a maximum length equal to twice the channel width and a maximum width equal to 0.75 times the channel width. The channel width can be measured, for example, at the channel base. Alternatively, the channel width—for all channel widths to be compared—can be measured in the area of ​​the inflection points of the flanks between channels and adjacent webs, or at half the height of a flank section that is straight when considering the channels and webs in cross-section, in which the inflection points lie or which is bounded by two inflection points.

[0079] In the Fig. 5A shows a section of an exemplary separator plate 2 of the system according to the type of system of the Fig. 1 Two rows of support structures 60 are visible. Fig. Figure 5a shows a view through the first single plate 2a and the second single plate 2b. The first row of support structures 60, along which in Fig. The section GG, shown in section 5A, is embossed in the first single plate 2a. This is, for example, in Fig. 5D. While the second individual plate 2b has no support structures 60 in the area of ​​section GG, the first individual plate 2a forms areas 37 with reduced groove depth in the area of ​​the raised sections 44. The support structures 60 of the first individual plate 2a are arranged in an orthogonal projection onto the second individual plate 2b, offset from the support structures 60 of the second individual plate 2b. The height of the webs 42 and channels 40, as well as the raised sections 44 and grooves 46 of the second individual plate 2b, is constant. The maximum height of the webs 32 of the first individual plate is also constant. However, the webs 42 of the second individual plate 2b have areas of nominal height H. N0 also areas with reduced height H N2 on, namely where the support structures 60 are arranged. In contact areas 24, the first single plate 2a rests on the second single plate 2b.

[0080] Fig. 5C shows a section along the in Fig. 5A, line FF. No support structures 60 are arranged in the separator plate 2 along this section. In this area, the height of the webs 42 and channels 40, as well as the height of the raised sections 44 and grooves 46 of the second individual plate 2b, is constant. The height of the webs 32 and channels 30, as well as the height of the raised sections 34 and grooves 36 of the first individual plate 2a, is also constant. The height of one web 32 is less than the height of one web 42.

[0081] In Fig. 5D is the in Fig. Section GG through support structures 60 is shown in Figure 5A. The support structures are located in the first single plate 2a. In contact areas 24, the raised sections 44 of the second single plate 2b abut grooves 36, the grooves 36 having a depth H in the contact areas 24 compared to the nominal depth H. N0' reduced depth H of the first single plate N1exhibit. The support structures 60 of the first single plate 2a originate from an opposite flank (in Fig. 5A of the left groove-limiting flank) compared with the support structures 60 of the second single plate 2b.

[0082] Furthermore, when comparing the Fig. 5B and Fig. 5D to recognize that the reduction of depth in Fig. 5B is more pronounced than in Fig. 5D.

[0083] The illustrated embodiment has the advantage that coolant can be guided directly under the webs 32 and 42, thus cooling the web surfaces. Furthermore, the nested structure allows for a small plate thickness s of the separator plate 2, which is exemplified in Fig. 5B is shown, in contrast to non-nested individual plates 2a, 2b, as they are shown, for example, in the Fig. 3 can be seen.

[0084] The Fig. Figures 6 to 8 each schematically show a sectional view of an exemplary setup for the system according to the type of system of Fig. 1. The section shown extends orthogonally to the plane of the plates and transversely to the elongated extent of the channel structures. An MEA 10 is arranged between two separator plates 2, 2' as described above. The MEA 10 comprises a membrane 14, which is covered on its front and back sides by two gas diffusion layers. Each of the separator plates 2, 2' comprises two individual plates 2a and 2b, which are supported in contact areas 24.

[0085] In Fig. In the section shown, the first individual plate 2a of the separator plate 2 does not form any support structures 60. The second individual plate 2b of the separator plate 2, however, does form support structures 60 as described above. In contact surfaces 25, the second individual plate 2b touches the MEA 10, more precisely the gas diffusion layer 16. The separator plate 2' is identical in construction to the separator plate 2. The first individual plate 2a contacts the MEA 10 in contact surfaces 25, which correspond to an upper surface of the webs 32. The separator plates 2 and 2' are arranged such that the support structures 60 overlap in an orthogonal projection onto the plane of the surface.

[0086] In Fig. In the section shown, the first individual plate 2a of the separator plate 2 does not form any support structures 60. The second individual plate 2b of the separator plate 2, however, does form support structures 60 as described above. In contact surfaces 25, the second individual plate 2b touches the MEA 10, more precisely the gas diffusion layer 16. The separator plate 2' is structurally identical to the separator plate 2, at least in the area shown. The first individual plate 2a contacts the MEA 10 in contact surfaces 25, which correspond to an upper surface of the webs 32. The separator plates 2 and 2' are arranged such that the support structures 60 are offset from each other in an orthogonal projection onto the plane of the planar surface. However, the separator plate 2' is perpendicular to the stacking direction z relative to the separator plate 2.h is rotated 180° in the plane of the plate such that the support structures 60 in separator plate 2 originate from the left groove flanks, while the support structures 60 in separator plate 2' originate from the right groove flanks. Separator plates 2 and 2' are nevertheless identical parts, but are only rotationally symmetrical in certain sections, particularly in the area of ​​the through-openings and distribution zones, while the electrochemically active area is not rotationally symmetrical.

[0087] In Fig. In the section shown, neither the first individual plate 2a nor the second individual plate 2b of the separator plate 2 form any support structures 60. While the first individual plate 2a of the second separator plate 2' also does not form any support structures 60, the second individual plate 2b of the separator plate 2', however, has support structures 60 of the type described above. In contact surfaces 25, the second individual plate 2b of the separator plate 2 touches the MEA 10, more precisely the gas diffusion layer 16. The separator plate 2' is structurally identical, at least in the area shown, to the separator plate 2' of the Fig. 7. The first single plate 2a of the separator plate 2' contacts the MEA 10 in contact surfaces 25, which correspond to an upper surface of the webs 32. The separator plates 2 and 2' are arranged such that the support structures 60 lie in an orthogonal projection onto the plane of the planar surface in the area of ​​the webs 42 of the second single plate 2b of the separator plate 2.

[0088] Fig. Figure 9 shows an exemplary separator plate 2 according to the above descriptions in a top view of the first individual plate 2a. The characteristics of the individual plates 2a, 2b described above with respect to the previous figures can be transferred to the present separator plate 2. Fig. Figure 9 highlights in particular that the support structures 60, of which only some are shown with reference symbols for clarity, can serve as guide structures. The support structures 60 are arranged in such a way that a fluid flowing in the cavity 19 (which is hidden in the figure) between the individual plates 2a and 2b is guided by the support structures 60. Arrows 100 and 200 are shown as examples to illustrate a flow direction. In the upper area of ​​the Fig. 9. The support structures are arranged offset from each other, resulting in a flow running obliquely to the elongated channel, see arrows 200. The flow is directed from the sides towards a center. In one area of ​​the Fig. 9 further down, the centered flow is directed parallel to channels 30 and 40, respectively, see arrows 200.

Claims

[1] Separator plate (2) for an electrochemical system (1), comprising a first individual plate (2a) and a second individual plate (2b) connected to the first individual plate (2a), wherein the first individual plate (2a) has, on a side facing away from the second individual plate (2b), first channels (30) formed next to one another for media guidance, which channels are separated from one another by first webs (32) formed between the first channels (30), wherein, on a side of the first individual plate (2a) facing the second individual plate (2b), the first channels (30) form first elevations (34) and the first webs (32) form first grooves (36), wherein the second individual plate (2b) has, on a side facing away from the first individual plate (2a), formed-in, adjacent second channels (40) for media guidance, which are separated from one another by second webs (42) formed between the second channels (40), wherein, on a side of the second individual plate (2b) facing the first individual plate (2a), the second channels (40) form second elevations (44) and the second webs (42) form second grooves (46), wherein the first individual plate (2a) is arranged relative to the second individual plate (2b) in such a way that the second elevations (44) project into the first grooves (36) at a distance from each other and the first elevations (34) project into the second grooves (46) at a distance from each other, characterized by , that at least one of the first grooves (36) and / or at least one of the second grooves (46) is formed in a section along its elongate extent transversely to its elongate extent in a stepped manner with a region (37, 47) of reduced groove depth - forming a support structure - wherein the region (37, 47) with reduced groove depth touches the opposite elevation (44, 34) of the other individual plate for supporting the first individual plate (2a) on the second individual plate (2b). [2] Separator plate (2) according to the previous claim, characterized by that a plurality of support structures are formed in one of the first grooves (36) and / or in one of the second grooves (46). [3] Separator plate (2) according to one of the preceding claims, characterized by that a plurality of first grooves (36) and / or a plurality of second grooves (46) each form at least one such support structure, in particular a plurality of first grooves (36) and / or a plurality of second grooves (46) each form a plurality of such support structures. [4] Separator plate (2) according to one of the preceding claims, wherein a contact plane in which the region (37, 47) with lesser depth touches the opposite elevation (44, 34) of the other individual plate for supporting the first individual plate (2a) on the second individual plate (2b) is inclined by a maximum of 15°, preferably a maximum of 10°, in particular a maximum of 5° to the plate plane. [5] Separator plate (2) according to one of the preceding claims, wherein the first channels (30) run at least partially, preferably completely, parallel to one another and / or wherein the second channels (40) run at least partially, preferably completely, parallel to one another and / or wherein the first channels (30) run at least partially, preferably completely, parallel to the second channels (40). [6] Separator plate (2) according to one of the preceding claims, characterized by that a width of the support structure measured transversely to the elongated extension of the respective groove decreases and increases again over the course of the support structure along the elongated extension of the groove. [7] Separator plate (2) according to one of the preceding claims, wherein the support structures of the first groove (36) and / or the second groove (46) in the respective elongated groove profile originate alternately from a first and a second groove flank delimiting the respective groove. [8] Separator plate (2) according to one of the preceding claims, characterized by that the first and / or second individual plate have a first and a second, and in particular a third, region, wherein the support structures in the first region are arranged offset from one another, the support structures in the second region are arranged to form rows transversely to the channel course, and in particular the support structures in the third region are arranged offset from one another. [9] Separator plate (2) according to one of the preceding claims, characterized bythat the first and / or second individual plate have a first and a second, and in particular a third, region, wherein the support structures in the first region have a region (37, 47) of reduced groove depth with a first depth (H N1 ), the support structures in the second region have a region (37, 47) of reduced groove depth with a second depth (H N2 ), wherein the first depth is not equal to the second depth, in particular wherein the support structures in the third region have a region (37, 47) of lesser groove depth with a third depth and the third depth is not equal to the first and / or second depth. [10] Separator plate (2) according to one of the preceding claims, characterized bythat the first individual plate has support structures and the second individual plate has support structures, wherein the support structures of the first individual plate are arranged offset from the support structures of the second individual plate in an orthogonal projection onto the second individual plate. [11] Separator plate (2) according to one of the preceding claims, wherein a height of the separator plate (2) measured perpendicular to a plane of the separator plate (2) is less than the sum of the material thicknesses of the two individual plates (2a, 2b) and twice the maximum channel bottom depth. [12] Separator plate (2) according to one of the preceding claims, wherein the first channels (30) and the second channels (40) are arranged in an electrochemically active region (18) of the separator plate (2), wherein the first webs (32) and the second webs (42) form contact surfaces for a membrane electrode unit (10), in particular for its gas diffusion layer (16). [13] Separator plate (2) according to one of the preceding claims, wherein the separator plate (2) is rotationally symmetrical by 180° at least in sections in the plane of the separator plate (2). [14] Arrangement (6) for an electrochemical system (1), comprising a plurality of separator plates (2) according to one of the preceding claims, wherein adjacent separator plates (2) are rotated by 180° relative to one another in the plane of the planar surface of one of the separator plates (2). [15] Arrangement (6) for an electrochemical system (1), comprising a plurality of separator plates (2) according to one of claims 1-14, wherein the separator plates (2) are designed such that in an orthogonal projection of a first separator plate onto an adjacent separator plate, at least regionally supporting structures of the first separator plate are arranged in regions of the adjacent separator plate in which supporting structures of the second separator plate are arranged. [16] Arrangement (6) for an electrochemical system (1), comprising a plurality of separator plates (2) according to one of claims 1-14, wherein the separator plates (2) are designed such that in an orthogonal projection of the support structures of a first separator plate onto an adjacent separator plate, support structures of the first separator plate are arranged at least in regions offset from support structures of the adjacent separator plate. [17] Arrangement (6) for an electrochemical system (1), comprising a plurality of separator plates (2) according to one of claims 1-14, wherein adjacent to a separator plate having first support structures, at least one adjacent separator plate is arranged which does not have such support structures or wherein adjacent to a separator plate having first support structures there is arranged at least one adjacent separator plate which - in an orthogonal projection of the support structures of the first separator plate onto the adjacent separator plate - has no support structures at least in the region of the support structures of the first separator plate.

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