DE102024104248A1 - Electrochemical cell stack - Google Patents

Abstract

An electrochemical cell stack (1) comprises a plurality of cells (2) which are separated from one another by bipolar plates (5, 5'), each cell (2) being formed from two half-cells (3, 4) between which a membrane (6) surrounded by a support frame (7) is arranged, and each half-cell (3, 4) containing a porous transport layer (10, 11). The support frame (7) has a stepped shape with two adjacent cross-sectional areas (12, 13), wherein an 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 a half-cell (3) extends into the step (17), and wherein the support frame (7) comprises at least one sealing arrangement (15) made of an electrically insulating sealing material which is injection-molded onto the support frame (7), wherein the sealing arrangement (15) comprises three sealing areas (19, 20, 21) each with at least one sealing lip (22, 22'), namely a first sealing area (19) and a second sealing area (20), which are to be assigned to the narrower of the two cross-sectional areas (12, 13) facing the membrane (6) and each contact exactly one bipolar plate (5, 5'), as well as a third sealing area (21), which is located on a side of the support frame (7) facing away from the step (17) and borders on an opening (9) of the support frame (7) provided for the passage of media and in this case contacts both bipolar plates (5, 5') against which the first and the second sealing region (19, 20) rest.

Description

The invention relates to an electrochemical cell stack comprising a plurality of electrochemical cells which are 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 located in each half-cell. The electrochemical cell stack is designed in particular in the form of a stack of electrolysis cells for hydrogen production.

An electrolysis cell stack is, for example, made from WO 2018/078157 A1 The known electrolysis cell stack, i.e. electrolyzer, comprises a plurality of bipolar plates arranged in a stack, with membranes and porous transport layers, which are also generally referred to as porous transport layers (PTL), being located between the bipolar plates. According to the WO 2018/078157 A1 The bipolar plates each have a layer of Ir, Ru, Rh, Os, their oxides or mixtures thereof. This layer is intended to act as a corrosion protection layer within the electrochemical system.

The EN 10 2021 203 983 A1 discloses a single cell arrangement for a fuel cell stack. Here, a framed membrane electrode arrangement comprises an electrochemically active region made of two gas diffusion layers and a catalyst-coated membrane, which are bonded to a frame. Furthermore, the arrangement according to the EN 10 2021 203 983 A1 a bipolar plate which has flow distribution and guide 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 for receiving a seal between the frame and the bipolar plate is formed on at least one of the surfaces of the bipolar plate.

Another membrane assembly, which separates an anode compartment from a cathode compartment within a fuel cell stack, is in the EN 10 2009 039 905 A1 described. The membrane of the arrangement according to the EN 10 2009 039 905 A1 has an elongated rectangular shape, with several channels, also generally referred to as ports, for the passage of working gases, i.e. operating media, on both narrow sides of the rectangular membrane. The membrane is part of an MEA plate, which is surrounded by an auxiliary assembly section, which is designed as a dimensionally stable support frame. Within a connecting section, which connects the MEA plate to the support frame, there is, among other things, a seal designed as a sealing bead.

One in the EN 10 2008 028 117 A1 The arrangement disclosed for a fuel cell comprises a bipolar plate in the form of a flat component to which a sealing element is positively attached. The sealing element is essentially U-shaped.

Further design options for seals in stacked arrangements of electrochemical cells are given, for example, in the documents EP 3 039 734 B1 , EN 10 2006 058 335 A1 , EN 11 2015 002 427 T5 and WO2021/104812A1 out.

The EP 3 356 575 B1 discloses a high or differential pressure electrolysis cell, which has 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 electrolyzer according to the EP 3 356 575 B1 a first porous support arranged between the first side of the membrane and the first flow field plate and which is relatively incompressible compared to other materials arranged between the plates. A first seal surrounds the first porous support, with a gap being formed 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. The device according to the invention further comprises EP 3 356 575 B1 a second porous carrier arranged on the second side of the membrane, which is more compressible than the first porous carrier. The electrolyzer after the EP 3 356 575 B1 shall be operable at a pressure difference between the high pressure side and the low pressure side of at least 40 bar.

The EN 10 2022 101 106 A1 describes an electrolysis cell with 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.

The invention is based on the object of developing an electrochemical cell stack which has been further developed compared to the above-mentioned prior art, particularly with regard to manufacturing and sealing aspects, for example in the form of a Stack of electrolysis cells for hydrogen production, whereby the cell stack should also be operable under a high differential pressure between the cathode side and the anode side.

This object is achieved according to the invention by an electrochemical cell stack, in particular a stack of electrolysis cells for hydrogen production, with the features of claim 1. The cell stack comprises, in a basic concept known per se, a plurality of electrochemical cells which are 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 in each half-cell there is a porous transport layer permeable to operating media of the electrochemical system.

According to the invention, the support frame has a stepped shape in cross-section, with two adjacent, for example rectangular, cross-sectional areas of different widths of the support frame. Generally, this is also referred to as adjacent, different-width areas. The width of these distinguishable areas is to be measured in the plane in which the support frame and the membrane lie. One edge of the membrane lies on the support frame in a step formed by the two cross-sectional areas.

The porous transport layer of one of the two half-cells of the electrochemical cell is designed as a pressure force-transmitting element and extends from the active field of the electrochemical cell enclosed by the support frame into the step mentioned, i.e. beyond the inner edge of the support frame. The pressure forces considered are forces that act in the normal direction to the mutually parallel planes in which the support frames and the bipolar plates are arranged.

The support frame comprises at least one sealing arrangement made of an electrically insulating sealing material which is injection-molded onto the support frame, the sealing arrangement comprising at least three sealing areas, each with at least one sealing lip, namely a first sealing area and a second thin sealing area, which are to be assigned to the narrower cross-sectional area facing the membrane. The thickness of all sealing areas is to be measured in the normal direction mentioned, i.e. orthogonal to the direction in which the width of the various cross-sectional areas of the support frame is to be measured. Each of the two sealing areas mentioned contacts exactly one bipolar plate. There is also a third sealing area which is located on a side of the support frame facing away from the step, i.e. on the outer side of the support frame, and borders on an opening in the support frame provided for the passage of media, i.e. on a port, and in this case contacts both bipolar plates on which the first and second sealing areas rest.

The 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 to the outside, with the first sealing area closing off the cathode side of the electrochemical cell and representing the innermost seal, i.e. the one furthest from the center of the active field. The active field accordingly has a smaller footprint on the cathode side than on the anode side. The membrane of the electrochemical cell rests on the first sealing area. In contrast to unclaimed solutions, the membrane is not supported by another seal at this point. Rather, on the side of the membrane that is directly opposite the cathode-side first sealing area, there is a volume section of the anode-side porous transport layer. This volume section is to be attributed to the element already mentioned that is suitable for transmitting pressure forces. From this element, which is in the form of a porous transport layer, the pressure forces can be transferred further into the adjacent bipolar plate.

Just like the membrane, the anode-side porous transport layer designed to transmit pressure forces also extends into the step, which is formed by the two cross-sectional areas of the support frame with different widths. A strip-shaped edge area of the membrane is thus arranged in an area that can hardly be used for electrochemical reactions. The mechanical support of the edge area of the membrane by a similarly strip-shaped area of the support frame makes a significant contribution to ensuring that no leaks can occur at the corresponding point, for example by the membrane being pressed into a gap at its edge. Rather, the strip-shaped edge area of the membrane is also pressed against the step by the pressure prevailing on the anode side.

The active field of the electrochemical cell is limited on the anode side by the second sealing area located further out. The anode-side porous transport layer can extend to this second sealing area, whereby this second sealing area together with further volume sections of the support frame in addition to the transport port layer can be used to transmit pressure forces acting between the bipolar plates.

The third sealing area encloses the outer edge of the support frame on the side facing away from the step. The third area has at least two sealing lips which run against the bipolar plate arranged above and below the support frame in the cross-section of the support frame.

The sealing material is made of an elastomeric material which has a Shore A hardness of 70-90 ShA, particularly at a temperature of 23°C ± 2 K. The Shore A hardness is specified for elastomers after measurement with a needle with a blunt tip. The front surface of the truncated cone has a diameter of 0.79 millimeters, the opening angle is 35°. Contact weight: 1 kg, holding time: 15 s. The material thickness should be at least 6 mm.

Examples of sealing materials suitable for forming the various sealing areas are FKM (used as an abbreviation for fluororubber mixture or fluorocarbon rubber) and EPDM (ethylene-propylene-diene rubber). Well-known technologies such as injection molding and edge bonding are suitable for applying the sealing material.

Basically, the minimum required seal coverage, i.e. the height of a sealing lip above the remaining sealing area, is a function or the result of material hardness, design, the tolerance chain and the system requirements, i.e. the pressure to be sealed in a half-cell. The seal coverage is basically a multiple of the height of any existing support structures, see below.

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

A sealing area is preferably designed to be almost as high as it is wide - seen in cross-section through the frame arrangement. The sealing area is therefore similar to an O-ring. The sealing function of the second sealing area is based primarily on axial compression of the sealing lip(s). The sealing function of the first and third sealing areas is based primarily on axial compression of the sealing lips and pressure activation, which is applied by the medium to be sealed and acts primarily horizontally on the sealing area, which leads to an additional axial sealing force on the sealing lips due to the preferably low compressibility of the sealing material.

The various sealing areas are generally made of preferably incompressible substances, in particular elastomers. This creates interactions 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 interactions increase the sealing effect of the support frame. Overall, the support frame is a highly integrated component that is embedded in a compact, easy-to-assemble, robust cell design. Due to the integration of various functions in the support frame and the resulting minimized number of individual components, the issue of assembly tolerances is largely eliminated in principle.

The support frame, which has at least three offset sealing areas in plan view, is suitable for use in an electrolyzer, for example, which is operated with a pressure difference of 100 bar between the cathode and anode sides. A particular advantage of this application is that separate equipment for compressing the hydrogen in order to feed it into a pipeline network or to supply it directly to a consumer can be largely or even completely eliminated.

Apart from the sealing areas, metallic or non-metallic materials are generally suitable for manufacturing the support frame. If a core of the support frame is made of metal, a substance located on the core can provide electrical insulation between the two bipolar plates that enclose the support frame between them.

It has proven to be useful if there is at least one electrically insulating area that connects the third sealing area with the second sealing area and/or the second sealing area with the first sealing area. The at least one electrically insulating area has no sealing function whatsoever, but merely serves as electrical insulation. This may be required on the anode side, the cathode side, or both sides of the support frame.

The at least one electrically insulating region is preferably made of the electrically insulating the sealing material from which the sealing arrangement is made. The electrically insulating region can be formed during the formation of the sealing arrangement. This electrically insulating region can be implemented both in a support frame with a metallic core and in a support frame made entirely of non-metallic materials. Preferably, however, the at least one electrically insulating region is arranged on a support frame made of electrically conductive material in order to reduce costs.

According to a possible further development, an elastic support in the electrically insulating area, which is preferably significantly wider than each of the sealing areas, is supported by elastic support structures, such as elastic knobs, webs, grooves or compression springs. The support structures can be made of any metallic and/or non-metallic materials.

The elastic flexibility of the support structures can be used in particular for assembly with a so-called SoftStop. Here, it is assumed that the support frame including the electrically insulating area represents a softer spring than the arrangement in the active field, which in addition to the membrane in particular includes the porous transport layers in both half-cells.

A HardStop concept, on the other hand, can be implemented with a support frame that does not have an electrically insulating area made of an elastic material such as the sealing material. In such a case, the adjacent bipolar plates can rest directly on the barely flexible core of the support frame, provided the core is made of an electrically insulating material. Otherwise, electrical insulation can be created by an electrically insulating coating that is located on at least one side of the support frame that is adjacent to a bipolar plate, as an electrically insulating area. Suitable electrically insulating coatings here include ceramic coatings such as Al ₂ O ₃ and/or SiO ₂ , or polymer coatings.

If a core element of the support frame is designed as a metal part, in particular a sheet metal part, a single or multi-layer design of this core element is possible. In the case of a two-layer design, one of the two sheet metal layers of the core element can form the step with a longer sheet metal layer arranged underneath it in the area of its front side. The sheet metal layers can be connected to one another by welding, for example.

When the support frame is made from sheet metal, particularly steel sheet metal, a three-dimensional structuring of the sheet metal offers advantages in terms of mechanical stability while at the same time using materials economically. For example, the metal core of the support frame, made from sheet metal using a forming process, describes a three-dimensionally formed cross-section. In this case, beads introduced into the sheet metal can run in the longitudinal direction of the frame in particular. After the sheet metal, which is the core element of the support frame, has been formed, the sheet metal can be overmolded in a single work step with an elastomer that forms all the sealing areas. At the same time, electrically insulating areas can be molded on.

According to one possible embodiment, the first sealing area is located between one of the two bipolar plates that sandwich the support frame and a layered arrangement that is designed to absorb compressive forces. The arrangement mentioned is made up of the membrane of the electrochemical cell, the porous transport layer of the anode-side half-cell that transmits compressive force, the second bipolar plate and a cooling field frame that can withstand greater mechanical loads than surrounding elements. Despite the low height of the electrochemical cells, a stable structure of the entire cell stack with highly effective seals both inside the cells and to the outside can thus be achieved.

• 1 ausschnittsweise ein erstes Ausführungsbeispiel eines elektrochemischen Zellenstapels im Querschnitt gesehen,
• 2 einen Ausschnitt aus der Anordnung nach 1,
• 3 einen Trägerrahmen des Zellenstapels nach 1 in Draufsicht,
• 4 - 10 Ausschnitte weiterer elektrochemischer Zellenstapel im Querschnitt gesehen,
• 11 einen weiteren Ausschnitt aus einem elektrochemischer Zellenstapel im Querschnitt gesehen, und
• 12 - 13 mögliche Dichtlippen für die Dichtbereiche im Querschnitt gesehen.

Several embodiments of the invention are explained in more detail below with reference to a drawing. In the drawing:

• 1 a first embodiment of an electrochemical cell stack seen in cross section,
• 2 an excerpt from the arrangement according to 1 ,
• 3 a support frame of the cell stack 1 in plan view,
• 4 - 10 Sections of further electrochemical cell stacks seen in cross section,
• 11 another section of an electrochemical cell stack seen in cross section, and
• 12 - 13 possible sealing lips for the sealing areas seen in cross section.

The following explanations refer to all embodiments, unless otherwise stated. Parts that correspond to one another or have essentially the same effect are identified with the same reference symbols in all figures.

An electrochemical cell stack, identified overall by the reference number 1, is an electrolyzer for producing hydrogen. The cell stack 1 comprises a plurality of electrochemical cells 2, i.e. electrolysis cells, each of which is made up of a first half cell 3 and a second half cell 4. Bipolar plates 5, 5' separate a half cell 3 of a first electrochemical cell 2 from a half cell 4 of a further 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 located in a support frame 7, which is positioned like a sandwich between two bipolar plates 5, 5' that are parallel to one another.

The floor plan of the support frame 7 is based on 3 The support frame 7 encloses an active field 8 of the electrolysis cell 2. Openings 9 arranged outside the active field 8, through which operating media of the cell stack 1 are passed, are generally referred to as ports. Within the electrolysis cells 2, the operating media flow, among other things, through porous transport layers 10, 11, which are located in the half cells 3, 4. As can be seen from all figures with the exception of the 3 As can be seen, the two half-cells 3, 4 are of different widths. Without restricting generality, in the present cases the anode-side half-cell 3 is referred to as the upper half-cell and the cathode-side half-cell 4 as the lower half-cell. The anode-side porous transport layer 10 protrudes above the cathode-side porous transport layer 11 in all cases. Accordingly, the support frame 7, which encloses the active field 8, has a stepped shape in cross-section.

The section of the support frame 7 considered in the exemplary embodiments borders on one hand on a port 9 and on the other hand on both half-cells 3, 4 of one and the same electrochemical cell 2. In said section there are two cross-sectional areas 12, 13 that can be distinguished from one another and have different widths. The support frame 7 comprises a single-part or multi-part core element 14, which takes up space in at least one of the cross-sectional areas 12, 13, as well as a sealing arrangement designated overall by 15. The sealing arrangement 15, like the core element 14, is assigned to a frame section 16.

The width of the frame section 16, which is to be measured in the plane of the support frame 7, is designated BR. The width of the core element 14, which is smaller in all cases, is designated BK. The height of the support frame 7, designated HR, together with other elements of the cell stack 1, specifies 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 results in the height HR of the frame section 16. In these cases too, the information "bottom" and "top" refers only to the figures and does not imply any statement about the actual installation position of the components 5, 5', 6, 16 in the cell stack 1.

A step 17 is formed between the cross-sectional area 12 and the cross-sectional area 13 on the side of the frame section 16 which faces the active field 8. An edge of the membrane 6, designated 18, lies in this step 17, remaining at least slightly spaced from the core element 14 due to the presence of the sealing arrangement 15. The sealing arrangement 15 comprises three sealing areas 19, 20, 21 which can be distinguished from one another. A first sealing area 19 and a second sealing area 20 can be distinguished from a third sealing area 21. The thickness of the first sealing area 19 and the second sealing area 20 corresponds to the height of a half-cell 3, 4. The third sealing area 21 fills the entire cell height. While the latter third sealing area 21 seals towards the port 9, the two sealing areas 19, 20 seal the active field 8. All sealing areas 19, 20, 21 are integral components of the support frame 7. In the exemplary embodiments, each sealing area 19, 20, 21 has at least one sealing lip 22. The sealing lips 22 shown in the sectional view each run in a ring shape in the plan view of the membrane 6.

In all the arrangements outlined, the first sealing area 19 has two sealing lips 22 which rest on the lower bipolar plate 5', as well as two further sealing lips 22 on which the membrane 6 rests. The total of four sealing lips 22 are directed against the pressure applied during operation of the cell stack 1, which increases the sealing effect with increasing pressure. The shape of the sealing lips 22 thus contributes to the self-sealing effect.

The porous transport layer 10 located above the membrane 6 represents a force-transmitting element which, together with the first sealing area 19, transmits forces F, i.e. pressure forces, between the bipolar plates 5, 5' arranged parallel to one another. In the embodiment according to the 1 to 2 a force effect on a cooling field frame 23 is illustrated, which is inserted into an embossed structure of the bipolar plate 5, designated 25. Elongated or circular embossed elements of the embossed structure 25 are designated 24, 26.

In the embodiments, the second sealing region 20 has only a single, Bipolar plate 5 has a sealing lip 22. Viewed from the active field 8, the second sealing region 20 is offset outwards from the first sealing region 19, i.e. in the direction of the port 9. The third sealing region 21, which is immediately adjacent to the port 9, has exactly two sealing lips 22 in the examples outlined, with each of these sealing lips 22 contacting one of the bipolar plates 5, 5', between which the support frame 7 is arranged.

In the examples according to the 1 , 2 , 4 , 5 , 6 , 7 , 8 , 9 In addition, there is an electrically insulating region 27 which connects the second sealing region 20 with the third sealing region 21 and rests against the upper bipolar plate 5 shown in the illustrations. Thus, the sealing regions 20, 21 and the electrically insulating region 27 extend in these cases over the entire cross-sectional area 13.

According to the 1 , 2 , 4 , 5 , 7 , 8 , 9 a further electrically insulating region 27' is present, which connects the second sealing region 20 with the first sealing region 19.

The electrically insulating areas 27, 27' are in accordance with the 1 , 2 , 4 , 5 , 7 , 8 , 9 formed from the electrically insulating sealing material with which the sealing areas 19, 20, 21 are formed.

According to 6 an electrically insulating region 27 is formed from an electrically insulating coating 31 which does not correspond to the sealing material.

The entire support frame 7 is thus given an elastic flexibility in the normal direction of the plane in which the support frame 7 lies.

In the example according to the 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, which comprises the core element 14 and the sealing arrangement 15, forms a structural unit that is not intended for disassembly.

Such a structural unit consisting of core element 14 and sealing arrangement 15 is also available in the design according to 4 given, whereby in this case the core element 14 is designed as a profiled sheet metal onto which the sealing arrangement 15 is molded. As far as the shape of the individual sealing areas 19, 20, 21 and the number of sealing lips 22 are concerned, there were no fundamental differences between the embodiment according to 4 and the embodiment according to 1 . In the case of 4 The core element 14, which is designed as a sheet metal, rests in several strip-shaped areas on the lower bipolar plate 5'. In the arrangement according to 4 On the left side of the core element 14, i.e. the side facing the port 9, an edge strip 28 is formed by the core element 14, which protrudes from the plane that is touched on the one hand by the lower bipolar plate 5' and on the other hand by the underside of the core element 14, and extends approximately over the entire height HR of the support frame 7. On the opposite, inner side of the core element 14, this runs out in the form of a flat band 29, to which the first sealing region 19 adjoins in the direction of the active field 8.

The support frame 7 after 5 differs from the carrier frame 7 according to the 1 and 2 by the fact that in the electrically insulating area 27 there are several elastic support elements 30, here indicated as helical springs, which exert forces F, as in 5 illustrated by arrows, between the bipolar plate 5 and the support frame 7. The core element 14 is in the case of 5 , as in the case of 1 , made of plastic.

In the example according to 6 the core element 14 is made of metal and is thus designed as an electrical conductor. In order to produce electrical insulation between the parallel bipolar plates 5, 5', which sandwich the support frame 7 between them, an electrically insulating region 27 in the form of an electrically insulating coating 31 is located on the top side of the support frame 7, i.e. on the cross-sectional region 13. An elastic deformability of the support frame 7 in the normal direction of the bipolar plates 5, 5' is possible in the case of 6 to a much lesser extent than in the cases of 1 , 4 and 5 .

Accordingly, in the case of 6 talked about a so-called HardStop concept.

In the case of 7 the support frame 7 has the same external shape as in the embodiment according to 1 In contrast to the embodiment according to 1 is in the case of 7 the cross-sectional area 13 is formed by a part of the core element 14 and the electrically insulating area 27. The core element 14 is also located in the cross-sectional area 12. Thus, in the embodiment according to 7 a distinctive SoftStop concept was implemented.

In the example according to 8 is the core element 14, as in the case of 4 , made of metal. Here, a tooth profile of the core element 14 is produced by forming, with the underside of the profile in its longitudinal grooves 32, i.e. beads, running in the direction of the profile and teeth 33 which are rectangular in cross section can be seen on the upper side of the profile. In adaptation to the cross section of the core element 14, the fourth sealing region 27 has a tooth structure 34 which is not visible from the outside and which provides a particularly stable bond between the core element 14 and the sealing arrangement 15.

Also in the example according to 9 There is a metallic core element 14, which is formed from two unequal widths of sheet metal strips 35, 36 welded together. The overall cross-sectional shape of the core element 14 of the support frame 7 according to 9 corresponds to the embodiment according to 1 .

In the example according to 10 the core element 14 made of plastic fills the entire height HR between the two bipolar plates 5. In this case, the sealing arrangement 15 only comprises the two interconnected sealing areas 19, 20 and the sealing area 21 separated from them.

According to 11 a core element 14 and a sealing arrangement 15 are present, whereby in this case the core element 14 is designed as a profiled sheet metal onto 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 according to 4 and the embodiment according to 1 . The same reference numerals as in these figures identify the same elements. Only the core element 14 is more delicate in the cross-sectional area 13 and forms a step 17 with the cross-sectional area 12 due to the deformation of the sheet metal. The electrically insulating area 27 between the third sealing area 21 and the second sealing area 20 has support structures 30 which support the bipolar plate 5. The further electrically insulating area 27' between the second sealing area 20 and the first sealing area 19 is made of sealing material like the electrically insulating area 27 and is molded onto the core element 14 in one piece and at the same time as the sealing arrangement 15. The frame arrangement 16 can be manufactured particularly inexpensively and quickly.

• zwei Dichtlippen 22 mit jeweils dreieckiger Grundform;
• vier Dichtlippen 22 mit jeweils dreieckiger Grundform;
• zwei Dichtlippen 22 mit jeweils rundlicher Grundform;
• vier Dichtlippen 22 mit jeweils stufenartiger, abgeflachter Grundform;
• vier Dichtlippen 22, zwei mit jeweils dreieckiger Grundform, zwei mit rundlicher Grundform.

The 12 shows possible designs of sealing lips 22 in the third area 21, which is molded onto a front side of a core element 14 that is only partially shown. Shown here from left to right:

• two sealing lips 22, each with a triangular basic shape;
• four sealing lips 22, each with a triangular basic shape;
• two sealing lips 22, each with a rounded basic shape;
• four sealing lips 22, each with a step-like, flattened basic shape;
• four sealing lips 22, two with a triangular basic shape, two with a rounded basic shape.

Such basic shapes can be combined as desired and the number of sealing lips 22 can be varied. The sealing lip designs shown for the third sealing area 21 can also be used for the first sealing area 19.

• zwei Dichtlippen 22', eine mit rundlicher Grundform und eine mit dreieckiger Grundform;
• zwei Dichtlippen 22' mit jeweils stufenartiger, abgeflachter Grundform;
• eine Dichtlippe 22' mit rundlicher Grundform;
• zwei Dichtlippen 22' mit jeweils dreieckiger Grundform;
• eine Dichtlippe 22' mit dreieckiger Grundform.

13 shows possible designs of a sealing lip 22' in the second area 20, which is molded in the area of the step 17 of a core element 14 that is only partially shown. Shown here from left to right are:

• two sealing lips 22', one with a rounded basic shape and one with a triangular basic shape;
• two sealing lips 22' each with a step-like, flattened basic shape;
• a sealing lip 22' with a rounded basic shape;
• two sealing lips 22' each with a triangular basic shape;
• a sealing lip 22' with a triangular basic shape.

Such basic shapes can be combined as desired and the number of sealing lips 22' can be varied.

List of reference symbols

1

electrochemical cell stack

2

electrochemical cell, electrolysis cell

3

Half cell

4

Half cell

5, 5'

Bipolar plate

6

membrane

7

Support frame

8

Active field

9

opening, port

10

porous transport layer, anode side

11

porous transport layer, cathode side

12

Cross-sectional area

13

Cross-sectional area

14

Core element

15

Sealing arrangement made of sealing material

16

Frame section

17

Level

18

Edge of the membrane

19

first sealing area on the active field with sealing lips 22

20

second sealing area on the active field with one-sided sealing lip 22'

21

third sealing area, adjacent to port 9

22

Sealing lip

22'

Sealing lip

23

Cooling field frame

24

Embossing element

25

Embossed structure

26

Embossing element

27, 27'

Electrically insulating area (without sealing function)

28

Sidebar

29

band

30

Support structures

31

electrically insulating coating

32

Groove

33

Tooth

34

Tooth structure

35

Sheet metal strips

36

Sheet metal strips

BR

Width of the frame element

BK

Width of the core element

F

Pressure force

HR

Height of the support frame

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• WO 2018078157 A1 [0002]
• DE 102021203983 A1 [0003]
• DE 102009039905 A1 [0004]
• DE 102008028117 A1 [0005]
• EP 3039734 B1 [0006]
• DE 102006058335 A1 [0006]
• EN 112015002427 T5 [0006]
• WO 2021104812 A1 [0006]
• EP 3356575 B1 [0007]
• DE 102022101106 A1 [0008]

Claims (10)

Electrochemical cell stack (1) comprising a plurality of electrochemical cells (2) which are separated from one another by bipolar plates (5), each electrochemical cell (2) being formed from two half-cells (3, 4), between which a membrane (6) surrounded by a support frame (7) is arranged, and each half-cell (3, 4) having a porous transport layer (10, 11), characterized in that the support frame (7) describes a stepped shape with at least two adjacent cross-sectional areas (12, 13) of different widths, an edge (18) of the membrane (6) lying in a 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) extending into the step (17) as a pressure force transmitting element, and the support frame (7) having at least one sealing arrangement (15) injection-molded onto the support frame (7) from a electrically insulating sealing material, wherein the sealing arrangement (15) comprises at least three sealing regions (19, 20, 21), each with at least one sealing lip (22, 22'), namely a first sealing region (19) and a second sealing region (20), which are to be assigned to the narrower of the two cross-sectional regions (12, 13) facing the membrane (6) and each contact exactly one bipolar plate (5, 5'), and a third sealing region (21), which is located on a side of the support frame (7) facing away from the step (17) and borders on an opening (9) of the support frame (7) provided for the passage of media and in this case contacts both bipolar plates (5, 5') against which the first and second sealing regions (19, 20) rest. Cell stack (1) after Claim 1 , characterized in that at least one electrically insulating region (27, 27') is present which 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). Cell stack (1) after Claim 2 , characterized in that the at least one electrically insulating region (27, 27') is formed from the sealing material or an electrically insulating coating (31). Cell stack (1) after Claim 2 or 3 , characterized by a plurality of elastic support structures (30) arranged in at least one electrically insulating region (27, 27'). Cell stack (1) according to one of the Claims 1 until 4 , characterized in that a core element (14) of the support frame (7) is made of plastic. Cell stack (1) according to one of the Claims 1 until 4 , characterized in that a core element (14) of the support frame (7) is designed as a metal part, in particular a sheet metal part. Cell stack (1) after Claim 6 , characterized in that the support frame (7) is constructed of two layers of sheet metal. Cell stack (1) after Claim 6 or 7 , characterized in that both the first sealing region (19) and the third sealing region (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 that the second sealing region (20) has at least one annular sealing lip (22') running parallel to the plane of the membrane (6). Cell stack (1) after Claim 6 , characterized in that the support frame (7) has a core element (14) in the form of a metal part three-dimensionally formed from a flat sheet metal strip. Cell stack (1) according to one of the Claims 1 until 9 , characterized in that the first sealing region (19) lies between one of the bipolar plates (5, 5') and a layered arrangement which is formed from the membrane (6), the porous transport layer (10) provided for transmitting compressive force, the further bipolar plate (5) and a cooling field frame (23).