Electrochemical Cell Stack

Abstract

The electrochemical cell stack (1) comprises a plurality of electrochemical cells (2) separated from one another by bipolar plates (5, 5'), each cell (2) being formed from two half cells (3, 4) in which a membrane (6) surrounded by a support frame (7) is disposed, and a porous transport layer (10, 11) is located within each half cell (3, 4). The support frame (7) exhibits a stepped shape having two adjacent cross-sectional areas (12, 13), an edge (18) of the membrane (6) is located in a step (17) formed by the cross-sectional areas (12, 13), the porous transport layer (10) of the half cell (3) extends into the step (17), the support frame (7) comprises at least one sealing structure injection molded onto the support frame (7) and comprising an electrically insulating sealing material, the sealing structure (15) comprising three sealing areas (19, 20, 21) each having at least one sealing lip (22, 22′). , in particular a first sealing area (19) and a second sealing area (20) which are arranged in the narrower of the two cross-sectional areas (12, 13) facing the membrane (6) and which each contact exactly one bipolar plate (5, 5'), and a third sealing area (21) which is on the side of the support frame (7) facing away from the step (17) and which borders an opening (9) in the support frame (7) provided for guiding a medium therethrough, and in which the first and second sealing areas (19, 20) contact both adjacent bipolar plates (5, 5').

Description

[Technical Field]

[0001] The present invention relates to an electrochemical cell stack comprising a plurality of electrochemical cells separated from one another by bipolar plates, each formed from two half-cells in which a membrane surrounded by a support frame is arranged, a porous transport layer being disposed in each half-cell, the electrochemical cell stack being in particular configured in the form of a stack of electrolysis cells for hydrogen production. [Background technology]

[0002] Electrolysis cell stacks are known, for example, from WO 2018 / 078157. The known electrolysis cell stack, i.e., electrolyzer, comprises a plurality of bipolar plates arranged in a stack configuration, which have a membrane and a porous transport layer, generally also referred to as a porous transport layer (PTL), disposed between the bipolar plates. According to WO 2018 / 078157, the bipolar plates each have a layer of Ir, Ru, Rh, Os, their oxides, or mixtures thereof. This layer is intended to function as a corrosion protection layer within the electrochemical system.

[0003] German Patent Application No. 102021203983 discloses a single cell configuration for a fuel cell stack. In this case, a framed membrane electrode configuration comprises an electrochemically active area consisting of two gas diffusion layers and a catalyst-coated membrane adhesively bonded to a frame. Furthermore, the configuration according to German Patent Application No. 102021203983 comprises a bipolar plate having flow distribution and conduction elements in a flow area corresponding to the electrochemically active area. In the edge area of ​​the bipolar plate surrounding the flow area, a sealing groove is formed on at least one of the surfaces of the bipolar plate to accommodate a sealant between the frame and the bipolar plate.

[0004] A further membrane assembly for separating the anode space from the cathode space in a fuel cell stack is described in DE 102009039905 A1. The membrane according to DE 102009039905 A1 has an elongated rectangular shape with a number of channels, also commonly referred to as ports, for passing the working gas, i.e., the operating medium, located on both narrow sides of the rectangular membrane. The membrane belongs to an MEA plate, which is surrounded by a mounting support configured as a dimensionally stable support frame. Inside the connection connecting the MEA plate to the support frame, there is a seal configured as a sealing bead.

[0005] The arrangement for a fuel cell disclosed in DE 10 2008 028 117 A1 comprises a bipolar plate in the form of a flat component to which a sealing element is form-fitted, the sealing element being substantially U-shaped.

[0006] Further construction options for seals in stacked configurations of electrochemical cells can be found, for example, in documents EP 3039734, DE 102006058335, DE 112015002427T5 and WO 2021 / 104812.

[0007] EP 3356575 discloses a high-pressure or differential pressure electrolysis cell having an electrochemical cell with a high-pressure side and a low-pressure side. The electrochemical cell includes two flow field plates and a membrane disposed between the flow field plates, the membrane having a first side on the low-pressure side and a second side on the high-pressure side. The electrolytic cell according to EP 3356575 further includes a first porous support disposed between the first side of the membrane and the first flow field plate, the first porous support being relatively incompressible compared to other materials disposed between the plates. A first seal surrounds the first porous support, forming a gap between the first porous support and the seal. A second seal is disposed between the second side of the membrane and the second flow field plate. The device according to EP 3356575 further includes a second porous support disposed on the second side of the membrane, the second porous support being more compressible than the first porous support. An electrolyser according to EP 3356575 must be able to operate with a pressure difference between the high pressure side and the low pressure side of at least 40 bar.

[0008] German Patent Application No. 102022101106 describes an electrolysis cell having a cell frame made of insulating plastic between two bipolar plates. At least one sealing element in the form of a flat seal is provided between the cell frame and each bipolar plate. The flat seal is integrated into the cell frame using a 2K injection molding process. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention is based on the object of providing an electrochemical cell stack that is further developed with respect to the aforementioned prior art, in particular with respect to the aspects of its manufacture and sealing, for example in the form of an electrolysis cell for hydrogen production, which cell stack must also be able to operate under high differential pressures between the cathode side and the anode side. [Means for solving the problem]

[0010] According to the invention, this object is achieved by an electrochemical cell stack, in particular an electrolysis cell stack for hydrogen production, having the features of claim 1. The cell stack comprises a plurality of electrochemical cells separated from one another by bipolar plates, in a basic concept known per se, each electrochemical cell being formed from two half-cells between which a membrane surrounded by a support frame is arranged, and a porous transport layer permeable to the operating medium of the electrochemical system is arranged in each half-cell.

[0011] According to the present invention, the support frame has a step-shaped cross section, i.e., two mutually bordering, e.g., rectangular cross-sectional areas of the support frame of different widths. Generally, mutually adjacent areas of different widths are involved. The widths of these mutually distinguishable areas must be measured in the plane in which the support frame and the membrane lie. One edge of the membrane rests on the support frame within the step formed by the two cross-sectional areas.

[0012] The porous transport layer of one of the two half-cells of the electrochemical cell is configured as a compressive force transmission element and extends from the active field of the electrochemical cell sealed by the support frame during the aforementioned step, i.e., beyond the inner edge of the support frame. The compressive force considered is a force acting in a direction normal to the parallel plane in which the support frame and the bipolar plate are arranged.

[0013] The support frame is injection-molded onto the support frame and includes at least one sealing structure made of an electrically insulating sealing material, which includes at least three sealing regions, each with at least one sealing lip, i.e., a first sealing region, and a second, thinner sealing region, which belongs to the narrower cross-sectional region facing the membrane. The thickness of all sealing regions must be measured in the normal direction, i.e., perpendicular to the direction in which the widths of the various cross-sectional regions of the support frame are measured. Each of the two sealing regions mentioned contacts exactly one bipolar plate. Furthermore, there is a third sealing region, which is arranged on the side of the support frame facing away from the step, i.e., on the outer side of the support frame, and which borders the opening, i.e., the port of the support frame provided for guiding the medium through, and which contacts both bipolar plates that the first and second sealing regions abut.

[0014] At least three sealing areas are integral components of the support frame and are arranged alternately from the inside out when viewed from the active field of the electrochemical cell. The first sealing area seals the cathode side of the electrochemical cell and constitutes the innermost seal, i.e., the seal closest to the center of the active field. As a result, the active field has a smaller cathode side contour than the anode side contour. The membrane of the electrochemical cell rests on the first sealing area. In contrast to the unclaimed solution, the membrane is not supported at this point by a separate seal. In fact, a volume of the porous transport layer on the anode side is disposed directly on the side of the membrane opposite the first sealing area on the cathode side. This volume belongs to the previously mentioned element, which is suitable for transmitting compressive forces. From this element in the form of a porous transport layer, the compressive forces can be further transmitted to the adjacent bipolar plate.

[0015] Just like the membrane, the anode-side porous transport layer, which is configured to transmit the compressive force, also extends into the step formed by the two cross-sectional areas of the support frame of different widths. Thus, the strip-like edge areas of the membrane are disposed in areas that are hardly usable anymore for electrochemical reactions. Mechanical support of the membrane's edge areas by the similar strip-like areas of the support frame significantly contributes to preventing leaks at the corresponding locations, for example, by pressing the membrane into gaps at its edges. Conversely, the strip-like edge areas of the membrane are also pressed against the step by the pressure prevailing on the anode side.

[0016] The active field of the electrochemical cell is further confined outward on the anode side by a second sealing area, which the anode-side porous transport layer can extend up to and which can be used with other volumes of the support frame in addition to the transport layer to transmit compressive forces acting between the bipolar plates.

[0017] The third sealing area seals the outer edge of the support frame on the side facing away from the step, and has at least two sealing lips in the cross section of the support frame that advance against bipolar plates arranged above and below the support frame.

[0018] The sealing material is made of an elastomer material with a Shore A hardness of 70-90 Shore A at 23°C ± 2K. The Shore A hardness is specified for the elastomer after measurement with a blunt needle. The end face of the truncated cone has a diameter of 0.79 mm and an opening angle of 35°. Support weight: 1 kg, holding time: 15 seconds. The material thickness must be at least 6 mm.

[0019] Examples of sealing materials suitable for forming the various sealing areas include FKM (used as an abbreviation for fluororubber compound or fluorocarbon rubber) and EPDM (ethylene propylene diene rubber). Known techniques such as injection molding and edge bonding are suitable for applying the sealing materials.

[0020] In principle, the minimum required sealant overlap, i.e., the height of the sealing lip above the remaining sealing area, is a function or result of material hardness, construction, tolerance chains, and system requirements, i.e., the pressure to be sealed into the half cell. In principle, the sealant overlap is a multiple of any existing support structure, see below.

[0021] Preferably, both the first and third sealing regions have at their ends facing away from the support frame at least two annular sealing lips each running parallel to the plane of the membrane, and the second sealing region has at least one sealing lip running in an annular manner parallel to the plane of the membrane. Possible configurations of sealing lips are shown in Figures 12 and 13.

[0022] The sealing areas are preferably configured so that, when viewed in cross section across the frame arrangement, their width and height are approximately the same. Thus, the sealing areas resemble O-rings. The sealing function of the second sealing area is primarily based on axial compression of the sealing lip. The sealing function of the first and third sealing areas is primarily based on axial compression of the sealing lip and pressure activation, which acts primarily horizontally on the sealing area and is applied by the medium to be sealed, and which preferably results in an additional axial sealing force on the sealing lip due to the low compressibility of the sealing material.

[0023] The various sealing regions generally consist of preferably incompressible materials, particularly elastomers. This allows for interaction between loads acting in different directions, for example, horizontal forces occurring in the plane of the support frame and vertical forces acting in the longitudinal direction of the stack, i.e., the cell stack. Such interaction increases the sealing effectiveness of the support frame. Overall, the support frame is a highly integrated component that is compact, easy to install, and assembled in a robust cell configuration. Due to the integration of various functions within the support frame and the resulting minimal number of individual components, assembly tolerance issues are largely eliminated by the configuration.

[0024] A support frame having at least three sealing areas offset from one another in plan view is suitable for use in electrolysers operating with a pressure difference of 100 bar between the cathode and anode sides, for example. A particular advantage of the present application is that it can largely or even completely dispense with the need for separate equipment for compressing hydrogen for supplying it to a pipeline network or directly to consumers.

[0025] Except for the sealing area, metallic or non-metallic materials are generally suitable for manufacturing the support frame. If the core of the support frame is made of metal, the material on the core can provide electrical insulation between the two bipolar plates, sealing the support frame between them.

[0026] It has proven useful if there is at least one electrically insulating region connecting the third sealing region to the second sealing region and / or the second sealing region to the first sealing region. The at least one electrically insulating region does not have a sealing function but functions only as an electrical insulator. This may be necessary on the anode side, the cathode side, or both sides of the support frame.

[0027] The at least one electrically insulating region is preferably formed from the electrically insulating sealing material from which the sealing structure is made. The electrically insulating region can be formed during the formation of the sealing structure. This electrically insulating region can be realized both in support frames with a metallic core and in support frames made entirely of non-metallic materials. However, preferably, the at least one electrically insulating region is arranged on a support frame made of a conductive material to reduce costs.

[0028] According to a possible further development, the resilient supports in the electrically insulating areas, which are preferably significantly larger than either of the sealing areas, are supported by resilient support structures such as resilient nubs, protrusions, grooves or compression springs. The support structures can be made of any metallic and / or non-metallic material.

[0029] The elastic flexibility of the support structure can be used in particular for installations with so-called soft stops, where it is assumed that the support frame including the electrically insulating regions is a more flexible spring than the arrangement in the active field, and that the support frame includes a porous transport layer in addition to the membrane, especially in the two half cells.

[0030] On the other hand, the hard stop concept can be realized using a support frame that does not have an electrically insulating region made of a resilient material such as a sealing material. In such cases, the adjacent bipolar plates can rest directly on the support frame's slightly flexible core, which is made of an electrically insulating material. In other cases, electrical insulation can be provided by an electrically insulating coating that is disposed as an electrically insulating region on at least one side of the support frame that abuts the bipolar plates. Ceramic coatings, such as those made of Al2O3 and / or SiO2, or polymer coatings are suitable as electrically insulating coatings.

[0031] If the core element of the support frame is constructed as a metal part, in particular as a sheet metal part, it can be constructed as a single layer or as a multilayer. In the case of a two-layer construction, one of the two sheet metal layers of the core element in the region of its end face can form a step with the longer sheet metal layer located below. The sheet metal layers can be joined together, for example, by welding.

[0032] When the support frame is made of sheet metal, especially sheet steel, the three-dimensional structure of the sheet metal provides advantages in terms of mechanical stability while using less material. For example, the metal core of the support frame made of sheet metal using a forming process has a three-dimensionally formed cross section. Beads introduced into the sheet metal can advance particularly in the longitudinal direction of the frame. After forming the core element of the support frame, the sheet metal can be overmolded with an elastomer, which forms all sealing areas in a single work step. At the same time, the electrical insulation areas can be injection molded.

[0033] According to one possible embodiment, the first sealing region is disposed between one of the two bipolar plates sandwiching the support frame and a layered structure intended to absorb compressive forces. The specified structure is formed by the membrane of the electrochemical cell, the porous transport layer of the anode half cell that transmits compressive forces, the second bipolar plate, and a cooling field frame that is mechanically more resilient than the surrounding elements. Despite the low height of the electrochemical cells, a stable structure of the overall cell stack can be achieved with highly effective seals both inside and outside the cells.

[0034] In the following, some exemplary embodiments of the invention are explained in more detail with the aid of the drawings. [Brief explanation of the drawings]

[0035] [Figure 1]1 shows details of a first exemplary embodiment of an electrochemical cell stack seen in cross section. [Figure 2] 2 shows a detail from the configuration according to FIG. 1. [Figure 3] 2 shows a support frame of the cell stack according to FIG. 1 in plan view; [Figure 4] 1 shows further electrochemical cell stack details seen in cross section. [Figure 5] 1 shows further electrochemical cell stack details seen in cross section. [Figure 6] 1 shows further electrochemical cell stack details seen in cross section. [Figure 7] 1 shows further electrochemical cell stack details seen in cross section. [Figure 8] 1 shows further electrochemical cell stack details seen in cross section. [Figure 9] 1 shows further electrochemical cell stack details seen in cross section. [Figure 10] 1 shows further electrochemical cell stack details seen in cross section. [Figure 11] 1 shows further details of an electrochemical cell stack seen in cross section. [Figure 12] 1 shows a possible sealing lip for the sealing area seen in cross section. [Figure 13] 1 shows a possible sealing lip for the sealing area seen in cross section. DETAILED DESCRIPTION OF THE INVENTION

[0036] Unless otherwise stated, the following description relates to all exemplary embodiments. In all figures, parts that correspond to one another or have essentially the same effect are designated by the same reference numerals.

[0037] The electrochemical cell stack, generally identified by the reference numeral 1, is an electrolyzer for producing hydrogen. The cell stack 1 comprises a plurality of electrochemical cells 2, i.e., electrolysis cells, each consisting of a first half-cell 3 and a second half-cell 4. Bipolar plates 5, 5' separate the half-cell 3 of a first electrochemical cell 2 from the half-cell 4 of a further electrochemical cell 2. The two half-cells 3, 4 of each electrochemical cell 2 are separated from each other by a membrane 6. The membrane 6 is disposed in a support frame 7, which is sandwiched between two mutually parallel bipolar plates 5, 5'.

[0038] The outline of the support frame 7 is shown in FIG. 3. The support frame 7 seals the active field 8 of the electrolysis cell 2. The openings 9 arranged outside the active field 8 and through which the working medium of the cell stack 1 is guided are generally referred to as ports. Within the electrolysis cell 2, the working medium flows, inter alia, through porous transport layers 10, 11 arranged in half cells 3, 4. As can be seen in all figures except FIG. 3, the two half cells 3, 4 are of different widths. Without limiting generality, the anode-side half cell 3 is referred to as the upper half cell, and the cathode-side half cell 4 is referred to as the lower half cell. In all cases, the anode-side porous transport layer 10 protrudes above the cathode-side porous transport layer 11. The support frame 7 sealing the active field 8 therefore has a stepped shape in cross section.

[0039] The portion of the support frame 7 considered in the exemplary embodiment borders on one side the port 9 and on the other side the two half-cells 3, 4 of the same electrochemical cell 2. In said portion there are two mutually distinguishable cross-sectional areas 12, 13 of different widths. The support frame 7 comprises a single- or multi-part core element 14, which occupies the space in the cross-sectional areas 12, 13 as well as in at least one of the sealing arrangements indicated by 15. Like the core element 14, the sealing arrangement 15 belongs to a frame portion 16.

[0040] The width of the frame portion 16, measured in the plane of the support frame 7, is indicated by BR. In all cases, the smaller width of the core element 14 is indicated by BK. The height of the support frame 7, indicated by HR, together with the further elements of the cell stack 1, determines the distance between two adjacent bipolar plates 5, 5'. The sum of the thickness of the cross-sectional area 13 and the thickness of the electrically insulating area 27 gives the height HR of the frame portion 16. Also in these cases, the designations "bottom" and "top" refer only to the diagram and do not imply any statement regarding the actual installation position of the components 5, 5', 6, 16 within the cell stack 1.

[0041] A step 17 is formed between the cross-sectional areas 12 and 13 on the side of the frame part 16 facing the active field 8. The edge of the membrane 6, indicated by 18, is located at this step 17 and remains at least slightly spaced from the core element 14 due to the presence of the sealing arrangement 15. The sealing arrangement 15 comprises three mutually distinguishable sealing areas 19, 20, 21. The first sealing area 19 and the second sealing area 20 can be distinguished from the third sealing area 21. The thickness of the first sealing area 19 and the thickness of the second sealing area 20 correspond in each case to the height of the half cells 3, 4. The third sealing area 21 fills the entire height of the cell. The latter third sealing area 21 seals towards the port 9, while the two sealing areas 19, 20 seal towards the active field 8. All sealing areas 19, 20, 21 are integral components of the support frame 7. In the exemplary embodiment, each sealing region 19, 20, 21 has at least one sealing lip 22. The sealing lips 22 shown in the cross-section of the membrane 6 each advance in an annular manner when viewed from above.

[0042] In all configurations shown, the first sealing area 19 has two sealing lips 22, which rest on the lower bipolar plate 5' and two further sealing lips 22, on which the membrane 6 rests. A total of four sealing lips 22 are resistant to the pressure acting during operation of the cell stack 1, which increases the sealing effect with increasing pressure. The shape of the sealing lips 22 therefore contributes to a self-sealing effect.

[0043] The porous transport layer 10 disposed above the membrane 6 constitutes a force-transmitting element which, together with the first sealing area 19, transmits the force F, i.e., the compressive force, between the bipolar plates 5, 5' arranged parallel to one another. The exemplary embodiment shown in Figures 1-2 illustrates the force effect on a cooling field frame 23 inserted into the embossment structure of the bipolar plate 5, indicated by 25. The elongated or circular embossment elements of the embossment structure 25 are indicated by 24, 26.

[0044] In the exemplary embodiment, the second sealing area 20 has only a single sealing lip 22 abutting the bipolar plate 5. When viewed from the active field 8, the second sealing area 20 is offset outward from the first sealing area 19, i.e., in the direction of the port 9. In the example shown, the third sealing area 21, which directly borders the port 9, has exactly two sealing lips 22, each of which contacts one of the bipolar plates 5, 5' on which the support frame 7 is arranged.

[0045] 1, 2, 4, 5, 6, 7, 8, 9, there is also present and visible in the illustrative drawings an electrically insulating region 27 which connects the second sealing region 20 to the third sealing region 21 and abuts the upper bipolar plate 5. The sealing regions 20, 21 and the electrically insulating region 27 therefore extend over the entire cross-sectional area 13 in these cases.

[0046] According to FIGS. 1, 2, 4, 5, 7, 8 and 9, there is a further electrically insulating region 27' connecting the second sealing region 20 to the first sealing region 19.

[0047] 1, 2, 4, 5, 7, 8 and 9, the electrically insulating regions 27, 27' are formed of an electrically insulating sealing material from which the sealing regions 19, 20, 21 are formed.

[0048] According to FIG. 6, the electrically insulating area 27 is formed by an electrically insulating coating 31 that is incompatible with the sealing material.

[0049] This gives the entire support frame 7 elastic flexibility in the direction normal to the plane in which it lies.

[0050] 1 and 2, the core element 14 of the support frame 7 is made of plastic. The sealing arrangement 15 is integrally connected to the core element 14, so that the support frame 7 with the core element 14 and the sealing arrangement 15 forms a structural unit that is not intended to be disassembled.

[0051] Such a structural unit consisting of a core element 14 and a sealing arrangement 15 is also present in the configuration shown in Figure 4, where the core element 14 is configured as a profiled metal sheet, from which the sealing arrangement 15 is injection-molded. As far as the shape of the individual sealing areas 19, 20, 21 and the number of sealing lips 22 are concerned, there is no fundamental difference between the embodiment shown in Figure 4 and the embodiment shown in Figure 1. In the case of Figure 4, the core element 14, configured as a metal sheet, rests on the lower bipolar plate 5' in strip-like areas. On the left-hand side of the core element 14 in the configuration shown in Figure 4, i.e., the side facing the port 9, an edge bar 28 is formed by the core element 14 and protrudes from a plane that contacts the lower bipolar plate 5' on the one hand and the underside of the core element 14 on the other hand and extends approximately over the entire height HR of the support frame. On the opposite inner side of the core element 14 , it is broken in the form of a flat band 29 which is bounded in the direction of the active field 8 by the first sealing region 19 .

[0052] The support frame 7 shown in Figure 5 differs from the support frame 7 shown in Figures 1 and 2 in that a plurality of elastic support elements 30, here compression springs shown as helical springs, are arranged in the electrically insulating area 27, which support elements transmit a force F between the bipolar plate 5 and the support frame 7, as illustrated by the arrows in Figure 5. In the case of Figure 5, as in Figure 1, the core element 14 is made of plastic.

[0053] In the configuration of the exemplary embodiment shown in Figure 6, the core element 14 is made of metal and is therefore configured as a conductor. To create electrical insulation between the parallel bipolar plates 5, 5' that sandwich the support frame 7, an electrically insulating region 27 in the form of an electrically insulating coating 31 is present on the upper side of the support frame 7, i.e., on the cross-sectional area 13. The elastic deformability of the support frame 7 in the normal direction to the bipolar plates 5, 5' is much less pronounced in Figure 6 than in Figures 1, 4, and 5. Figure 6 is therefore referred to as a hard stop concept.

[0054] In the case of Fig. 7, the support frame 7 has the same external shape as in the exemplary embodiment shown in Fig. 1. In contrast to the exemplary embodiment shown in Fig. 1, in the case of Fig. 7, the cross-sectional area 13 is formed by a part of the core element 14 and an electrically insulating area 27. The core element 14 is also arranged within the cross-sectional area 12. Thus, in the embodiment shown in Fig. 7, a significant soft-stop concept is realized.

[0055] In the embodiment shown in Figure 8, the core element 14 is made of metal, as in Figure 4. The core element 14 has a tooth profile created by forming longitudinally running grooves 32, or beads, on the underside of the profile and rectangular teeth 33 in the cross section on the upper side of the profile that are visible. To match the cross section of the core element 14, the fourth sealing region 27 has a toothed structure 34 that is not visible from the outside and provides a particularly stable bond between the core element 14 and the sealing arrangement 15.

[0056] A metallic core element 14 is also present in the exemplary embodiment shown in Figure 9, but in this case it is formed of two sheet metal strips 35, 36 of unequal widths that are welded together. The overall cross-sectional shape of the core element 14 of the support frame 7 shown in Figure 9 corresponds to the embodiment shown in Figure 1.

[0057] 10, the plastic core element 14 fills the entire height HR between the two bipolar plates 5. In this case, the sealing arrangement 15 comprises only two interconnected sealing areas 19, 20 and a separate sealing area 21.

[0058] According to FIG. 11 , there is a core element 14 and a sealing arrangement 15, in this case the core element 14 being configured as a profiled metal sheet from which the sealing arrangement 15 is injection-molded. As far as the shape of the individual sealing areas 19, 20, 21 and the number of sealing lips 22 are concerned, there are no fundamental differences between the embodiment shown in FIG. 4 and the embodiment shown in FIG. 1 . The same reference numerals in these figures refer to identical elements. Only the core element 14 is filigree in the cross-sectional area 13, which forms a step 17 with the cross-sectional area 12 by forming the metal sheet. The electrically insulating area 27 between the third sealing area 21 and the second sealing area 20 has a support structure 30 that supports the bipolar plate 5. Similar to the electrically insulating area 27, a further electrically insulating area 27′ between the second sealing area 20 and the first sealing area 19 is made of sealing material and is injection-molded integrally with it, simultaneously forming the sealing arrangement 15 on the core element 14. The frame structure 16 is particularly inexpensive and quick to manufacture.

[0059] Figure 12 shows a possible configuration of the sealing lip 22 in the third region 21, injection moulded onto the end face of the core element 14, which is only partially shown. Here, from left to right: two sealing lips 22, each having a triangular basic shape; four sealing lips 22, each having a triangular basic shape; two sealing lips 22, each having a circular basic shape; four sealing lips 22, each having a stepped flattened basic shape; Four sealing lips 22 can be seen, two each having a triangular basic shape and two each having a circular basic shape.

[0060] Such basic shapes can be combined as required and the number of sealing lips 22 can be varied. The sealing lip configurations shown for the third sealing region 21 can also be used for the first sealing region 19.

[0061] Figure 13 shows possible configurations of the sealing lip 22' of the second region 20 which is injection molded in the region of the step 17 of the core element 14, which is only partially shown. Here, from left to right: two sealing lips 22', one having a circular basic shape and one having a triangular basic shape; two sealing lips 22' each having a stepped, flattened basic shape; one sealing lip 22' having a circular basic shape, two sealing lips 22' each having a triangular basic shape, One sealing lip 22' can be seen, which has a triangular basic shape.

[0062] Such basic shapes can be combined as required and the number of sealing lips 22' can be varied. [Explanation of symbols]

[0063] 1. Electrochemical cell stack 2. Electrochemical cells, electrolytic cells 3 half cells 4 half cells 5, 5' Bipolar Plate 6 Membranes 7 Support frame 8 Active Field 9 Openings, ports 10 Porous transport layer, anode side 11 Porous transport layer, cathode side 12 Cross-sectional area 13 Cross-sectional area 14 Core Elements 15 Sealing structure made of sealing material 16 Frame part 17 steps 18 Edge of membrane 19 First sealing area on the active field with sealing lip 22 20 a second sealing area on the active field with a sealing lip 22' on one side 21 Third sealing area bordering port 9 22 sealing lip 22' sealing lip 23 Cooling Field Frame 24 Raised Elements 25 Raised structure 26 Raised Elements 27, 27' Electrical insulation area (without sealing function) 28 Edge bar 29 bands 30 Support structure 31 Electrical insulating coating 32 Groove 33 teeth 34 Tooth-like structure 35 sheet metal strips 36 sheet metal strips BR Frame element width BK Core element width F Compression force HR Support Frame Height

Claims

1. 1. An electrochemical cell stack (1), comprising a plurality of electrochemical cells (2) separated from one another by bipolar plates (5), each formed from two half cells (3, 4) in which a membrane (6) surrounded by a support frame (7) is arranged, a porous transport layer (10, 11) being disposed within each half cell (3, 4), the support frame (7) being, when viewed in cross section, representative of a step shape having at least two mutually adjacent cross-sectional areas (12, 13) of different widths, one edge (18) of the membrane (6) being located in a step (17) formed by the two cross-sectional areas (12, 13), the porous transport layer (10) of one of the two half cells (3) extending into the step (17) as a compressive force transmission element, the support frame (7) being formed from an electrochemical cell (2) injection-molded onto the support frame (7).

1. An electrochemical cell stack (1), comprising at least one sealing arrangement (15) of insulating sealing material, characterized in that the sealing arrangement (15) comprises at least three sealing areas (19, 20, 21) each having at least one sealing lip (22, 22'), in particular a first sealing area (19) and a second sealing area (20) belonging to the narrower of the two cross-sectional areas (12, 13) facing the membrane (6) and each contacting exactly one bipolar plate (5, 5'), and a third sealing area (21) arranged on a side of the support frame (7) facing away from the step (17) and bordering an opening (9) in the support frame (7) provided for guiding a medium therethrough, in which case the first and second sealing areas (19, 20) contact the two bipolar plates (5, 5') on which they abut.

2. 2. The cell stack (1) of claim 1, characterized in that at least one electrically insulating region (27, 27') is present and connects the third sealing region (21) to the second sealing region (20) and / or the second sealing region (20) to the first sealing region (19).

3. 3. A cell stack (1) according to claim 2, characterized in that said at least one electrically insulating area (27, 27') is formed by said sealing material or electrically insulating coating (31).

4. 4. A cell stack (1) according to claim 2 or 3, characterized by a plurality of resilient support structures (30) arranged in the at least one electrically insulating region (27, 27').

5. A cell stack (1) according to any one of claims 1 to 4, characterized in that the core element (14) of the support frame (7) is made of plastic.

6. The cell stack (1) according to any one of claims 1 to 4, characterized in that the core element (14) of the support frame (7) is configured as a metal part, in particular as a sheet metal part.

7. 7. A cell stack (1) according to claim 6, characterized in that the support frame (7) is constructed of two layers from sheet metal.

8. 8. A cell stack (1) according to claim 6 or 7, characterized in that both the first sealing area (19) and the third sealing area (21) each have, at their ends facing away from the support frame (7), at least two annular sealing lips (22) running parallel to the plane of the membrane (6), and the second sealing area (20) has at least one sealing lip (22') running in an annular manner parallel to the plane of the membrane (6).

9. 7. A cell stack (1) according to claim 6, characterized in that the support frame (7) has core elements (14) in the form of metal sections formed three-dimensionally from flat sheet metal strips.

10. 10. A cell stack (1) according to any one of claims 1 to 9, characterized in that the first sealing area (19) is located between one of the bipolar plates (5, 5') and a layered arrangement formed from the membrane (6), and the porous transport layer (10) is provided for transmitting compressive forces to the further bipolar plate (5) and to a cooling field frame (23).

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