Electrochemical cell stack

Abstract

An electrochemical cell stack (1) comprising a plurality of cells (2) separated from one another by bipolar plates (5, 5 '), where each cell (2) is formed by two half-cells (3, 4) between which a membrane (6) surrounded by a support frame (7) is arranged, and where a porous transport layer (10, 11) is present in each half-cell (3, 4). The support frame (7) describes a step shape having two adjacent cross-sectional areas (12, 13), in which the edge (18) of the membrane (6) lies in a step (17) formed by the cross-sectional areas (12, 13) and the porous transport layer (10) of the half-cell (3) extends into the step (17), and in which the porous transport layer (10) of the half-cell (3) extends into the step (17). According to the invention, the support frame (7) comprises at least one sealing arrangement (15) injection molded onto the support frame (7) and comprising an electrically insulating sealing material, according to the invention, the sealing arrangement (15) comprises three sealing regions (19, 20, 21), each having at least one sealing lip (22, 22 '), in particular a first sealing region (19) and a second sealing region (20) and a third sealing region (21), which are assigned to narrower regions of the two cross-sectional regions (12, 13) facing the membrane (6), the first sealing region and the second sealing region each contact exactly one bipolar plate (5, 5 '), and the third sealing region is located on a side of the support frame (7) facing away from the step (17) and adjoins an opening (9) of the support frame (7) provided for guiding a medium through, and contacting two bipolar plates (5, 5 ') adjacent to the first sealing region (19) and the second sealing region (20).

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, wherein each electrochemical cell is formed from two half-cells, between which a membrane surrounded by a support frame is arranged, and wherein a porous transport layer is provided in each half-cell. The electrochemical cell stack is particularly designed in the form of an electrolysis cell stack for hydrogen production. Background Art

[0002] For example, WO 2018 / 078157 A1 discloses an electrolysis cell stack. This known electrolysis cell stack, or electrolysis cell, comprises a plurality of bipolar plates arranged in a stack, with membranes and porous transport layers, often also referred to as porous transport layers (PTLs), disposed between the bipolar plates. According to WO 2018 / 078157 A1, each bipolar plate has a layer of Ir, Ru, Rh, Os, their oxides, or mixtures thereof. This layer is intended to serve as a corrosion protection layer within the electrochemical system.

[0003] DE 10 2021 203 983 A1 discloses a single-cell arrangement for a fuel cell stack. In this case, a frame-based membrane electrode arrangement includes an electrochemically active region consisting of two gas diffusion layers adhesively bonded to the frame and a catalyst-coated membrane. Furthermore, the arrangement according to DE 10 2021 203 983 A1 includes a bipolar plate having flow distribution and conduction elements in a flow region corresponding to the electrochemically active region. In an edge region of the bipolar plate surrounding the flow region, a sealing groove is formed on at least one of the surfaces of the bipolar plate to accommodate a seal between the frame and the bipolar plate.

[0004] DE 10 2009 039 905 A1 describes another membrane assembly for separating the anode and cathode spaces within a fuel cell stack. The membrane according to the arrangement described in DE 10 2009 039 905 A1 has an elongated rectangular shape, with multiple channels for the passage of the working gas, or operating medium, often also referred to as ports, located on the two narrower sides of the rectangular membrane. The membrane is attached to an MEA plate, which is surrounded by a mounting aid designed as a dimensionally stable support frame. The connection between the MEA plate and the support frame contains a seal designed as a sealing flange.

[0005] DE 10 2008 028 117 A1 discloses an arrangement for a fuel cell comprising a bipolar plate in the form of a flat component to which a sealing element is attached in a form-fitting manner. The sealing element is substantially U-shaped.

[0006] Further design options for seals in stacked arrangements of electrochemical cells can be found, for example, in documents EP 3 039 734 B1, DE 10 2006 058 335 A1, DE 11 2015 002 427 T5 and WO 2021 / 104812 A1.

[0007] EP 3 356 575 B1 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 comprises two flow field plates and a membrane, which is arranged between the flow field plates and has a first side on the low-pressure side and a second side on the high-pressure side. Furthermore, the electrolysis cell according to EP 3 356 575 B1 comprises a first porous support, which is arranged between the first side of the membrane and the first flow field plate and is relatively incompressible compared to other materials arranged 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 arranged between the second side of the membrane and the second flow field plate. Furthermore, the device according to EP 3 356 575 B1 comprises a second porous support, which is arranged on the second side of the membrane and is more compressible than the first porous support. The electrolysis cell according to EP 3 356 575 B1 should be operable at a pressure difference between the high-pressure side and the low-pressure side of at least 40 bar.

[0008] DE 10 2022 101 106 A1 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

[0009] The present invention is based on the object of providing an electrochemical cell stack which has been further developed compared to the aforementioned prior art, in particular with regard to production and sealing, for example in the form of an electrolysis cell stack for hydrogen production, wherein the cell stack should also be capable of operating at high pressure differences between the cathode side and the anode side.

[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, each electrochemical cell being formed, in a basic concept known per se, from two half-cells, between which a membrane surrounded by a support frame is arranged, and in each half-cell a porous transport layer permeable to the operating medium of the electrochemical system is provided.

[0011] According to the invention, the support frame has a stepped cross-section, wherein there are two adjacent, for example rectangular, cross-sectional areas of different widths of the support frame. These are generally adjacent areas of different widths. The width of these 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 at the step formed by the two cross-sectional areas.

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

[0013] The support frame comprises at least one sealing arrangement injection-molded onto the support frame and made of an electrically insulating sealing material, the sealing arrangement comprising at least three sealing areas, each having at least one sealing lip, namely a first sealing area and a thin second sealing area, the first sealing area and the second sealing area belonging to the narrower cross-sectional area facing the membrane. The thickness of all sealing areas must be measured along the mentioned normal direction, i.e. orthogonally to the direction along which the width of the respective cross-sectional area of ​​the support frame is to be measured. Each of the two mentioned sealing areas contacts exactly one bipolar plate. In addition, there is a third sealing area, which is arranged on the side of the support frame facing away from the step, i.e. on the outside of the support frame, and is adjacent to the opening of the support frame, i.e. the port, which is arranged for guiding the medium through, and contacts the two bipolar plates against which the first sealing area and the second sealing area are supported.

[0014] At least three sealing areas are integral components of the support frame and, viewed from the active field of the electrochemical cell, are staggered from the inside out, wherein 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 profile on the cathode side than on the anode side. The membrane of the electrochemical cell rests on the first sealing area. In contrast to the unclaimed solution, the membrane is not supported by another seal. In fact, the volume portion of the porous transport layer on the anode side is arranged on the side of the membrane directly opposite the first sealing area on the cathode side. This volume portion belongs to the element already mentioned, which is suitable for transmitting compressive forces. The compressive force can be further transmitted from this element in the form of a porous transport layer to the adjacent bipolar plate.

[0015] Like the membrane, the porous transport layer on the anode side, designed to transmit compressive forces, also extends into the step formed by the two cross-sectional areas of the support frame of different widths. Consequently, the strip-shaped edge region of the membrane is positioned in an area that is virtually no longer available for electrochemical reactions. The mechanical support of the membrane edge region by similar strip-shaped areas of the support frame significantly contributes to preventing leakage at corresponding points, for example by pressing the membrane into a gap at its edge. Conversely, the strip-shaped edge region of the membrane is also pressed against the step by the pressure prevailing on the anode side.

[0016] The active field of the electrochemical cell is limited on the anode side by a second sealing area further outward. The anode-side porous transmission layer can extend to this second sealing area, and in addition to the transmission layer, this second sealing area and other volume parts of the support frame can also be used to transmit the compressive forces acting between the bipolar plates.

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

[0018] The seal material consists of an elastomeric material with a Shore A hardness of 70–90 ShA, typically at 23°C ± 2 K. The Shore A hardness is specified for the elastomer after measurement using a needle with a blunt tip. The diameter of the truncated cone end is 0.79 mm, and the opening angle is 35°. The supported weight is 1 kg, and the holding time is 15 s. The material thickness should be at least 6 mm.

[0019] Examples of sealing materials suitable for forming the various sealing areas are 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 material.

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

[0021] Preferably, both the first sealing area and the third sealing area each have at least two annular sealing lips extending parallel to the plane of the membrane at the ends of the first sealing area and the third sealing area facing away from the support frame, and the second sealing area has at least one sealing lip extending in an annular manner parallel to the plane of the membrane. Figure 12 and Figure 13 A possible design of the sealing lip is shown in .

[0022] The sealing area is preferably designed to be nearly as high as it is wide, viewed in a cross section through the frame arrangement. The sealing area thus resembles an O-ring. The sealing function of the second sealing area is primarily based on the axial compression of the sealing lip. The sealing function of the first and third sealing areas is primarily based on the axial compression of the sealing lip and on pressure activation, which acts primarily horizontally on the sealing area and is exerted by the medium to be sealed. Due to the preferably low compressibility of the sealing material, this pressure activation results in additional axial sealing forces on the sealing lip.

[0023] The various sealing areas are typically composed of a preferably incompressible material, particularly an elastomer. This results in an interaction between loads acting in different directions, such as horizontal forces generated in the plane of the support frame and vertical forces acting in the longitudinal direction of the stack, i.e., the cell stack. This interaction enhances the sealing effect of the support frame. Overall, the support frame is a highly integrated component embedded in a compact, easy-to-install, and robust battery design. Due to the integration of various functions in the support frame and the resulting minimal number of individual components, assembly tolerance issues are largely eliminated by design.

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

[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 that enclose the support frame between them.

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

[0027] Preferably, the at least one electrically insulating region is formed from an electrically insulating sealing material used to form the sealing arrangement. The electrically insulating region can be formed during the formation of the sealing arrangement. This electrically insulating region can be implemented in a support frame having a metal core or in a support frame formed entirely of non-metallic materials. However, preferably, the at least one electrically insulating region is arranged on a support frame formed of an electrically conductive material to reduce costs.

[0028] According to a possible further development, the elastic support in the electrically insulating area, which is preferably much wider than any of the sealing areas, is supported by an elastic support structure, such as an elastic nub, a protrusion, a groove or a compression spring. The support structure can be made of any metallic and / or non-metallic material.

[0029] The elastic compliance of the support structure can be used in particular for installations with so-called soft stops. It is assumed that the support frame, including the electrically insulating region, is a softer spring than the arrangement in the active field and, in addition to the membrane, also includes, in particular, the porous transport layer in both half-cells.

[0030] Alternatively, the hard stop concept can be implemented with a support frame that lacks electrically insulating regions made of resilient materials, such as sealing materials. In this case, adjacent bipolar plates can rest directly on the nearly inflexible core of the support frame, provided the core is made of an electrically insulating material. Alternatively, electrical insulation can be provided by an electrically insulating coating applied to at least one side of the support frame that bears against the bipolar plates, serving as the electrically insulating region. 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 designed as a metal part, in particular a sheet metal part, it can be designed as a single-layer or multi-layer core element. In the case of a two-layer design, one of the two sheet metal layers of the core element can form a step in its end area, with the longer sheet metal layer being arranged underneath. The sheet metal layers can be joined together, for example, by welding.

[0032] If the support frame is made of sheet metal, particularly steel, its three-dimensional structure offers advantages in terms of mechanical stability while using less material. For example, the metal core of the support frame, formed from sheet metal using a forming process, can have a three-dimensionally shaped cross-section. The flange introduced into the sheet metal can, in particular, extend in the longitudinal direction of the frame. After forming the sheet metal as the core element of the support frame, it can be overmolded with an elastomer in a single working step, which forms all sealing areas. Simultaneously, the electrically insulating areas can be injection molded.

[0033] According to one possible embodiment, the first sealing area is provided between one of the two bipolar plates of the clamp support frame and a layered structure designed to absorb compressive forces. The designated structure is formed by the membrane of the electrochemical cell, the porous transmission layer of the anode-side half-cell that transmits compressive forces, the second bipolar plate, and the cooling field frame, which is mechanically more resilient than the surrounding elements. Despite the low height of the electrochemical cells, a stable structure for the entire cell stack is achieved, with efficient sealing both inside and outside the cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Several exemplary embodiments of the present invention are explained in more detail below with the aid of the accompanying drawings, in which:

[0035] Figure 1 shows a detail of a first exemplary embodiment of an electrochemical cell stack viewed in cross section;

[0036] Figure 2 Shown according to Figure 1 Details of the layout structure;

[0037] Figure 3 The plan view shows the Figure 1 A support frame for a battery stack;

[0038] Figures 4 to 10 Details of other electrochemical cell stacks are shown viewed in cross section;

[0039] Figure 11 shows another detail of the electrochemical cell stack viewed in cross section;

[0040] Figures 12 to 13 A possible sealing lip for the sealing area is shown in cross section. DETAILED DESCRIPTION

[0041] Unless otherwise specified, the following description relates to all exemplary embodiments. In all figures, parts that correspond to each other or have substantially the same function are denoted by the same reference numerals.

[0042] The electrochemical cell stack, generally designated by reference numeral 1, is an electrolyzer for producing hydrogen. The cell stack 1 includes a plurality of electrochemical cells 2, or 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 another electrochemical cell 2. The two half-cells 3, 4 of each electrochemical cell 2 are separated from one another by a membrane 6. The membrane 6 is disposed in a support frame 7, which is sandwiched between two parallel bipolar plates 5, 5'.

[0043] Figure 3 The support frame 7 is shown in outline. The support frame 7 encloses the active field 8 of the electrolysis cell 2. The openings 9 arranged outside the active field 8 and through which the operating medium of the cell stack 1 is conducted are generally referred to as ports. Within the electrolysis cell 2, the operating medium flows, among other things, through the porous transport layers 10, 11 arranged in the half cells 3, 4. Figure 3As can be seen in all figures except the Figure 1, the two half-cells 3, 4 have different widths. Without limiting generality, in this case, 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 beyond the cathode-side porous transport layer 11. Consequently, the support frame 7 enclosing the active field 8 has a stepped cross-section.

[0044] The portion of the support frame 7 considered in the exemplary embodiment is adjacent to the port 9 on one side and to two half-cells 3, 4 of the same electrochemical cell 2 on the other side. Within this portion, there are two mutually distinguishable cross-sectional areas 12, 13 of different widths. The support frame 7 includes a single- or multi-part core element 14 occupying the space in at least one of the cross-sectional areas 12, 13, and a sealing arrangement denoted by 15. Like the core element 14, the sealing arrangement 15 belongs to the frame portion 16.

[0045] The width of the frame portion 16, measured in the plane of the support frame 7, is denoted by BR. In each case, the smaller width of the core element 14 is denoted by BK. The height of the support frame 7, denoted by HR, determines, together with the other elements of the cell stack 1, 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. In these cases, the terms "bottom" and "top" also refer only to the drawings and do not imply any assertion regarding the actual installation position of the components 5, 5', 6, 16 in the cell stack 1.

[0046] A step 17 is formed between cross-sectional area 12 and cross-sectional area 13 on the side of frame portion 16 facing active field 8. The edge of membrane 6, designated 18, lies within this step 17 and, due to the presence of sealing arrangement 15, is at least slightly spaced from core element 14. Sealing arrangement 15 comprises three distinguishable sealing areas 19, 20, and 21. The first and second sealing areas 19, 20 can be distinguished from the third sealing area 21. In each case, the thickness of first sealing area 19 and second sealing area 20 corresponds to the height of half-cells 3, 4. Third sealing area 21 fills the entire height of the cell. When the rear third sealing area 21 seals toward port 9, both seals 19, 20 seal active field 8. All sealing areas 19, 20, 21 are integral components of support frame 7. In the exemplary embodiment, each sealing area 19, 20, 21 has at least one sealing lip 22. The sealing lips 22 shown in the cross-sectional view of membrane 6 each extend annularly when viewed from above.

[0047] In all the illustrated arrangements, the first sealing area 19 has two sealing lips 22 resting on the lower bipolar plate 5 ′ and two further sealing lips 22 on which the membrane 6 rests. The four sealing lips 22 in total are oriented to resist the pressure acting during operation of the stack 1, which increases the sealing effect as the pressure increases. Thus, the shape of the sealing lips 22 contributes to the self-sealing effect.

[0048] The porous transport layer 10 arranged above the membrane 6 forms a force transmission element which, together with the first sealing area 19 , transmits a force F, ie a compressive force, between the bipolar plates 5 , 5 ′ arranged parallel to one another. Figures 1 to 2 The exemplary embodiment shown in illustratively illustrates the force effect on a cooling field frame 23 which is inserted into an embossed structure, designated 25, of a bipolar plate 5. The elongated or round embossed elements of the embossed structure 25 are designated 24,26.

[0049] In the exemplary embodiment, the second sealing area 20 has only a single sealing lip 22 that bears against the bipolar plate 5. Viewed from the active field 8, the second sealing area 20 is offset outwardly 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 is directly adjacent to the port 9, has exactly two sealing lips 22, each of which contacts one of the bipolar plates 5, 5' between which the support frame 7 is arranged.

[0050] exist Figure 1 、 Figure 2 、 Figure 4 、 Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 、 Figure 9 In the exemplary embodiment shown in , there is also an electrically insulating region 27, which connects the second sealing region 20 to the third sealing region 21 and bears against the upper bipolar plate 5, as can be seen in the illustration. Thus, in these cases, the sealing regions 20, 21 and the electrically insulating region 27 extend over the entire cross-sectional area 13.

[0051] according to Figure 1 、 Figure 2 、 Figure 4 、 Figure 5 、 Figure 7 、 Figure 8 、 Figure 9 , there is a further electrically insulating region 27 ′ which connects the second sealing region 20 to the first sealing region 19 .

[0052] according to Figure 1 、 Figure 2 、 Figure 4 、 Figure 5 、 Figure 7 、 Figure 8 and Figure 9 The electrically insulating regions 27 , 27 ′ are formed by the electrically insulating sealing material forming the sealing regions 19 , 20 , 21 .

[0053] according to Figure 6 , the electrically insulating region 27 is formed by an electrically insulating coating 31 which does not correspond to the sealing material.

[0054] This gives the entire support frame 7 elastic compliance in the direction normal to the plane in which the support frame 7 lies.

[0055] exist Figure 1 and Figure 2 In the exemplary embodiment shown in , 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 including the core element 14 and the sealing arrangement 15 forms a structural unit that is not intended to be disassembled.

[0056] This structural unit comprising the core element 14 and the sealing arrangement 15 is also present in Figure 4 In the design shown in FIG, and in this case, the core element 14 is designed as a profiled metal sheet onto which the sealing arrangement 15 is injection molded. As regards the shape of the individual sealing areas 19, 20, 21 and the number of sealing lips 22, Figure 4 The embodiment shown in Figure 1 There is no fundamental difference between the embodiments shown in . Figure 4 In the case of , the core element 14 designed as a metal plate rests on the lower bipolar plate 5 ' in the form of a plurality of strip-shaped areas. Figure 4 On the left-hand side of the core element 14 in the arrangement shown in FIG, i.e. the side facing the port 9, an edge bar 28 is formed by the core element 14 and projects from a plane tangential to the lower bipolar plate 5′ on the one hand and to the underside of the core element 14 on the other hand and extends approximately over the entire height HR of the support frame 7. On the opposite inner side of the core element 14, the core element extends in the form of a flat strip 29 which adjoins the first sealing area 19 in the direction of the active field 8.

[0057] Figure 5 The support frame 7 shown in FIG. Figure 1 and Figure 2 The support frame 7 shown in FIG. 1 differs in that a plurality of elastic support elements 30, here represented as compression springs in the form of coil springs, are provided in the electrically insulating region 27, which transmit the force between the bipolar plate 5 and the support frame 7 as shown by Figure 5 The force F is shown by the arrow in . Figure 5 In the case of Figure 1As in the case of , the core element 14 is made of plastic.

[0058] exist Figure 6 In the exemplary embodiment of the design shown in , the core element 14 is made of metal and is therefore designed as an electrical conductor. In order to provide electrical insulation between the parallel bipolar plates 5, 5' between which the support frame 7 is sandwiched, 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. Figure 6 In the case of Figure 1 、 Figure 4 and Figure 5 Therefore, Figure 6 It is called the hard stop concept.

[0059] exist Figure 7 In the case of Figure 1 The same external shape as in the exemplary embodiment shown in FIG. Figure 1 In contrast to the exemplary embodiment shown in Figure 7 In the case of , the cross-sectional area 13 is formed by a portion of the core element 14 and the electrically insulating area 27. The core element 14 is also arranged in the cross-sectional area 12. Thus, in Figure 7 In the embodiment shown in , a clear soft stop concept is implemented.

[0060] exist Figure 8 In the exemplary embodiment shown in FIG, the core element 14 is made of metal, and Figure 4 The core element 14 has a toothed profile produced by shaping, wherein on the underside of the profile there are grooves 32, i.e., flanges, extending in the longitudinal direction, and rectangular teeth 33 are visible in cross section on the upper side of the profile. To match the cross section of the core element 14, the fourth sealing area 27 has a toothed structure 34, which is not visible from the outside and provides a particularly stable bond between the core element 14 and the sealing arrangement 15.

[0061] The metal core element 14 is also present in Figure 9 In the exemplary embodiment shown in , although in this case the metal core element is formed by two metal sheet strips 35 , 36 of unequal width which are welded together. Figure 9 The overall cross-sectional shape of the core element 14 of the support frame 7 shown in FIG corresponds to Figure 1 The embodiment shown in .

[0062] exist Figure 10In the exemplary embodiment shown in , 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 .

[0063] according to Figure 11 , there is a core element 14 and a sealing arrangement 15, and in this case the core element 14 is designed as a profiled metal sheet onto which the sealing arrangement 15 is injection-molded. With regard to the shape of the individual sealing areas 19, 20, 21 and the number of sealing lips 22, Figure 4 The embodiment shown in Figure 1 There are no fundamental differences between the embodiments shown in FIG. The same reference numerals in these figures denote the same elements. Only the core element 14 is more elongated in the cross-sectional area 13 and, due to the metal sheet, forms a step 17 with the cross-sectional area 12. The electrically insulating region 27 between the third sealing region 21 and the second sealing region 20 comprises a support structure 30 for supporting the bipolar plate 5. Like the electrically insulating region 27, the further electrically insulating region 27′ between the second sealing region 20 and the first sealing region 19 is formed from a sealing material and is injection-molded integrally onto the core element 14 simultaneously with the sealing arrangement 15. The frame device 16 is particularly inexpensive and quick to manufacture.

[0064] Figure 12 A possible design of a sealing lip 22 in a third region 21 is shown, which is injection-molded onto the end face of the only partially shown core element 14. Here one sees from left to right:

[0065] two sealing lips 22, each of which has a triangular basic shape;

[0066] Four sealing lips 22, each of which has a triangular basic shape;

[0067] two sealing lips 22, each of which has a rounded basic shape;

[0068] Four sealing lips 22, each of the four sealing lips having a stepped, flat basic shape;

[0069] Of the four sealing lips 22 , two sealing lips each have a triangular basic shape and two sealing lips have a rounded basic shape.

[0070] Such basic shapes can be combined as desired, and the number of sealing lips 22 can vary. The sealing lip design shown for the third sealing area 21 can also be used for the first sealing area 19.

[0071] Figure 13A possible design of the sealing lip 22' in the second region 20 is shown, which is injection-molded in the region of the only partially shown step 17 of the core element 14. Here one sees from left to right:

[0072] two sealing lips 22 ′, one sealing lip having a rounded basic shape and one sealing lip having a triangular basic shape;

[0073] Two sealing lips 22 ′, each of which has a stepped, flat basic shape;

[0074] a sealing lip 22 ′ having a rounded basic shape;

[0075] two sealing lips 22 ′, each of which has a triangular basic shape;

[0076] A sealing lip 22' having a triangular basic shape.

[0077] Such basic shapes can be combined as desired, and the number of sealing lips 22 ′ can vary.

[0078] Reference Signs List

[0079] 1 Electrochemical cell stack

[0080] 2 Electrochemical cells, electrolytic cells

[0081] 3 half-cells

[0082] 4 half-cells

[0083] 5.5' bipolar plate

[0084] 6 membrane

[0085] 7 Support frame

[0086] 8 Active Field

[0087] 9 Openings and ports

[0088] 10 Porous transport layer, anode side

[0089] 11 Porous transport layer, cathode side

[0090] 12 Cross-sectional area

[0091] 13 Cross-sectional area

[0092] 14 core elements

[0093] 15 Sealing arrangement made of sealing material

[0094] 16 Frame part

[0095] 17 steps

[0096] 18 Edge of membrane

[0097] 19 First sealing area with sealing lip 22 with respect to the active field

[0098] 20 Second sealing area with one-sided sealing lip 22 ′ with respect to the active field

[0099] 21 The third sealing area adjacent to port 9

[0100] 22 Sealing lip

[0101] 22' sealing lip

[0102] 23 Cooling Field Framework

[0103] 24 Imprinting components

[0104] 25 Imprinted structure

[0105] 26 Imprinting components

[0106] 27, 27' Electrically insulating area (no sealing function)

[0107] 28 Edge Rod

[0108] 29 belts

[0109] 30 Support structure

[0110] 31 Electrical insulation coating

[0111] 32 grooves

[0112] 33 teeth

[0113] 34 tooth structure

[0114] 35 Metal Lath

[0115] 36 Metal Laths

[0116] BR Width of the frame element

[0117] BK Width of core element

[0118] F Compression force

[0119] HR Height of the support frame.

Claims

1. An electrochemical cell stack (1) comprising a plurality of electrochemical cells (2) separated from each other by bipolar plates (5), wherein: Each electrochemical cell (2) is formed by two half-cells (3, 4), between which a membrane (6) is arranged, which is surrounded by a support frame (7), and wherein a porous transport layer (10, 11) is provided in each half-cell (3, 4), characterized in that the support frame (7) observed in cross section describes a step shape with at least two mutually adjacent cross-sectional areas (12, 13) of different widths, one edge (18) of the membrane (6) is located in the step (17) formed by the two cross-sectional areas (12, 13), and the porous transport layer (10) of one of the two half-cells (3) extends into the step (17) as a compression force transmission element, and wherein the support frame (7) comprises at least one sealing arrangement structure made of an electrically insulating sealing material injection-molded onto the support frame (7). A structure (15) is provided, wherein the sealing arrangement structure (15) comprises at least three sealing areas (19, 20, 21), each having at least one sealing lip (22, 22'), specifically a first sealing area (19) and a second sealing area (20) and a third sealing area (21), wherein the first sealing area and the second sealing area belong to the narrower areas of the two cross-sectional areas (12, 13) facing the membrane (6) and each contacts exactly one bipolar plate (5, 5'), and the third sealing area is arranged on a side of the support frame (7) facing away from the step (17) and is adjacent to an opening (9) of the support frame (7) configured for guiding the passage of a medium, and in this case contacts the two bipolar plates (5, 5') against which the first sealing area (19) and the second sealing area (20) are supported.

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

3. The battery stack (1) according to claim 2, characterized in that The at least one electrically insulating region (27, 27') is formed by a sealing material or an electrically insulating coating (31).

4. The battery stack (1) according to claim 2 or 3, characterized in that A plurality of elastic bearing structures (30) are arranged in the at least one electrically insulating region (27, 27').

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

7. The battery stack (1) according to claim 6, characterized in that The support frame (7) is made of metal plates in two layers.

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

9. The battery stack (1) according to claim 6, characterized in that The supporting frame (7) has a core element (14) in the form of a metal part formed three-dimensionally from flat sheet metal strips.

10. The battery 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 by the membrane (6), the porous transport layer (10) configured to transmit compressive forces, the other bipolar plate (5) and a cooling field frame (23).

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