Electrochemical cell of a stacked arrangement of a PEM electrolyser or an aem electrolyser or a PEM fuel cell

Abstract

The invention relates to an electrochemical cell (10) of a stacked arrangement (52) of a PEM electrolyser or a PEM fuel cell having a plurality of electrochemical cells (10) which have porous transport structures (20, 22) on both sides of a coated membrane (14) on a cathode side (24) and an anode side (26) and which are sealed on both sides by means of seals (28, 30) within the stacked arrangement (52). Gaps (34) produced on both sides of the coated membrane (14) between the seals (28, 30) and the porous transport structures (20, 22) are at least partially filled by deformable sealing elements (4), in particular sealing noses or sealing lips, provided on the seals (28, 30). The invention also relates to the use of the electrochemical cell (10) in a stacked arrangement (52) of a PEM electrolyser or a PEM fuel cell.

Description

[0001] Electrochemical cell of a stacked arrangement of a PEM electrolyzer or an AEM electrolyzer or a PEM fuel cell

[0002] Technical area

[0003] The invention relates to an electrochemical cell of a stacked arrangement of a PEM electrolyzer or an AEM electrolyzer or a PEM fuel cell with a plurality of electrochemical cells. These cells have porous transport structures on both sides of a coated membrane on a cathode side and an anode side and are sealed on both sides by seals within the stacked arrangement. The invention further relates to a method for producing a deformable, circumferential seal of an electrochemical cell, designed as a sealing cord, and to the use of the electrochemical cells in a stacked arrangement of a PEM electrolyzer or an AEM electrolyzer or a PEM fuel cell.

[0004] State of the art

[0005] WO 18 / 196947 A1 relates to a method for operating a water electrolysis device. In the electrolysis device, water coming from a PEM electrolyzer is fed in a water circuit to a first heat exchanger for cooling, then to an ion exchanger, then to a second heat exchanger for heating, and then back to the PEM electrolyzer. The heat exchangers form secondary parts of a common heat transfer medium circuit, which has a cooling device through which the heat transfer medium flow is partially or not at all passed to control and / or regulate the temperature of the water fed to the ion exchanger and / or the PEM electrolyzer. PEM electrolyzers, AEM electrolyzers, and PEM fuel cells are constructed, like heat exchangers, from stacked flat elements. The flat elements form an anode side chamber and a cathode side chamber with a selectively separating membrane.Analogous to the PEM fuel cell, the membrane in the PEM electrolyzer should only allow cations, typically H+ ions, to pass through to the cathode. In the case of an alkaline AEM electrolyzer, which is operated with an alkaline solution, such as a KOH solution, on the anode and / or cathode sides, only anions, typically OH- ions, pass through towards the anode. For the sake of simplicity, the PEM electrolyzer is explained below as an example. In the case of a PEM electrolyzer, water is added to the anode-side chamber, and water and oxygen are removed. The cathode-side chamber preferably contains the majority of the hydrogen produced. The hydrogen chamber on the cathode side preferably has a higher pressure, for example on the order of 30 bar, which is higher than the pressure acting on the anode-side chamber, which is on the order of between 1 bar and 5 bar.The aforementioned chambers must be sealed against each other in the stack. Sealing can be achieved using sealing plates, a surface-applied sealant, or sealing cords in the form of O-rings.

[0006] The flat seals require a relatively high compression force and a high material input. Since the active area in electrolysis cells or fuel cells is usually formed by a flow field and usually by a porous structure, the aim is to connect the seal to the flow field without a gap in order to prevent reaction reactants or products from flowing through a gap around the flow field instead of passing through it. In particular, at a port or at a connection area, a seal without a gap on, for example, a flow field is not always possible. Here, the differential pressure described above presses the membrane into the gap between opposing seals and the opposing flow field. If, for example, O-rings are used for sealing, the O-rings are usually round in terms of production technology, i.e.They are manufactured with a circular cross-section and circular main dimensions. This results in main dimensions the size of the cross-section, which necessitates relatively large molds for injection molding. Furthermore, large machines with relatively high production costs are required, even if the area inside a large sealing ring were filled with many small sealing rings to maximize the mold's capacity.

[0007] Description of the invention

[0008] An electrochemical cell of a stacked arrangement of a PEM or AEM electrolyzer or a PEM fuel cell is proposed, comprising a plurality of electrochemical cells that have porous transport structures on both sides of a coated membrane on a cathode side and an anode side, and that are sealed on both sides by seals within the stacked arrangement. Gaps that arise on both sides of the coated membrane between the seals and the porous transport structures are at least partially filled by deformable sealing elements provided on the seals, in particular sealing noses or sealing lips.

[0009] Due to the design of the seals proposed according to the invention, the pressure conditions within a stack arrangement can be used advantageously to deform the sealing elements, which are cast or formed on the seals, due to the prevailing pressure distribution in such a way that they lie sealingly against the membrane and an inadmissible deflection, i.e. an inadmissible deformation of the membrane due to the pressure gradient, is avoided.

[0010] In an advantageous embodiment of the electrochemical cell proposed according to the invention, the seals are designed as flat seals or as sealing cords.

[0011] In an advantageous development of the electrochemical cell proposed according to the invention, the seals can be provided with a stiffening insert. This significantly increases the component stability and, in particular, the dimensional stability of a stacked arrangement of a PEM electrolyzer or a PEM fuel cell, which is subsequently stacked from a plurality of electrochemical cells.

[0012] In an advantageous development of the electrochemical cells proposed according to the invention, seals are designed to run all the way around the porous transport structures. By designing the seals in this way, the greatest possible sealing reliability can be achieved.

[0013] In an advantageous embodiment of the electrochemical cell proposed according to the invention, the seals comprise deformable sealing elements facing the porous transport structures, which are designed in particular as sealing lips or as sealing noses.

[0014] In an advantageous development of the electrochemical cell proposed according to the invention, the sealing elements facing the porous transport structures are deformable such that, due to a pressure distribution on the cathode and / or anode side, they are placed in contact with an upper side and / or a lower side of the membrane in the gaps to be sealed. Thus, by utilizing the pressure distribution prevailing in the electrochemical cell, an advantageous sealing of the porous transport structures against escaping media can be achieved without the need for additional sealing measures.

[0015] In an advantageous development of the electrochemical cell, regions of the seals and / or the porous transport structures adjacent to an upper side and / or a lower side of the membrane are designed as rounded portions or in an elliptical geometry.

[0016] Advantageously, the electrochemical cell is designed such that the porous transport structures are provided with a beveled edge that forms a contact surface with the beveled edge of an adjacent seal. Alternatively, it can be provided that a beveled edge with one or two rounded edges forms a contact surface for the coated membrane.

[0017] The geometry of such a contact surface is designed, for example, such that the height of the edge break is up to 50% of the membrane's thickness, and the width of the edge break can be one to ten times the height of the edge break. A contact surface configured in this way effectively prevents or limits deformation within the stack arrangement, which could occur due to the prevailing pressure gradients and place significant mechanical stress on the membrane.

[0018] The electrochemical cell proposed according to the invention is designed such that the thickness of the porous transport structures is between 50 pm and 5000 pm, preferably between 200 pm and 2000 pm, and particularly preferably between 300 and 500 pm. This allows for the fact that smaller thicknesses can be selected for a porous transport structure comprising an expanded metal mesh.

[0019] In the electrochemical cell proposed according to the invention, seals designed as sealing cords have a flat side facing the membrane.

[0020] Advantageously, the flat side of a seal designed as a sealing cord is designed such that at least one end, preferably both ends of the flat side, are provided with a sealing element which can be designed, for example, in the shape of a nose.

[0021] In the electrochemical cell proposed according to the invention, in the case of the formation of an edge break as an elliptical geometry, this is designed in such a way that a surface on a long semi-axis of the elliptical geometry is assigned to the seals and a surface on a short semi-axis of the elliptical geometry is assigned to the membrane.

[0022] The invention further relates to a method for producing a deformable, circumferential seal of an electrochemical cell designed as a sealing cord, comprising the following method steps: a) introducing a serpentine-shaped recess into a molding tool, b) applying a flat cover to the serpentine-shaped recess in the molding tool filled with a molding compound to form a flat side with sealing elements adjoining it, and c) removing the sealing cord with flat side and the sealing elements delimiting it from a molding tool.

[0023] Furthermore, the invention relates to the use of the electrochemical cell in a stack arrangement of a PEM electrolyzer or a PEM fuel cell.

[0024] Advantages of the invention

[0025] The solution proposed by the invention makes it possible to utilize the pressure distribution around an electrochemical cell accommodated in a stacked arrangement to seal against preferably circumferentially designed, deformable sealing elements against a coated membrane on which, for example, the flow field is located. This eliminates the need for additional sealing elements, especially circumferential ones.

[0026] Advantageously, the sealing elements are cast or injection-molded directly onto sealing cords or flat gaskets, for example, during their manufacture, and are preferably made of a deformable plastic material. Due to the pressure distribution around the electrochemical cell, both the cathode side, which has a higher pressure level, and the anode side, which generally has a lower pressure level, can be effectively sealed against one another. In particular, the solution proposed according to the invention makes it possible to ensure that gaps that arise during construction of the electrochemical cell due to manufacturing tolerances are, even if not completely filled, at least reduced by the seals. This prevents excessive deformation of the coated membrane, which in extreme cases could lead to its fracture.The solution proposed according to the invention makes it possible, in particular, to create contact surfaces that are delimited by round or elliptical seals that prevent buckling of the sensitive coated membrane.

[0027] For example, the solution proposed according to the invention can be used to create contact surfaces that are formed on the one hand by a broken edge of the porous transport structure and on the other hand by a corresponding broken edge on the seal surrounding it. The broken edge is particularly burr-free. Instead of a contact surface formed by a broken edge, a curve or an elliptical geometry can also be formed. The respective broken edges are dimensioned such that they are on the order of magnitude of the typical deformation values ​​of the coated membrane. The height of the broken edges is up to 50% of the thickness of the coated membrane, while the width of the broken edge can be between one and ten times the height of the broken edge in order to achieve effective support for the coated membrane.Typically, the thickness values ​​of a porous transport structure are between 50 pm and 5000 pm, especially between 300 pm and 500 pm.

[0028] The solution proposed by the invention allows the pressure conditions on the anode or cathode side of the electrochemical cell to be exploited to prevent leakage of process gases or process fluids H2O, H2, or O2 under relatively high pressure toward the gaps. In particular, creeping or swelling of the coated membrane into gaps, particularly those with sharp edges, can be avoided. The coated membrane swells by absorbing water, and the swelling behavior can depend on the contact pressure. Since the counterpressure is lower in the gap or free space, the membrane swells excessively here, so that the solution proposed by the invention can effectively counteract membrane weakening. This preventative measure prevents contact between the porous transport structures and sharp edges.Furthermore, the mechanical load during operation is effectively counteracted due to the prevailing pressure gradient on both sides of the coated membrane as well as crack formation in the coated membrane.

[0029] Due to the prevailing pressure conditions, in particular the pressure differences on the cathode and anode sides of the electrochemical cell proposed according to the invention, the sealing force depends on the prevailing pressures on the cathode and anode sides.

[0030] By applying the solution proposed according to the invention, the tolerances of the components used can be broadened, and furthermore, the service life is extended due to the improved support against mechanical stress. Thinner coated membranes can be used because their low mechanical strength is no longer the sole design criterion due to the lower deformation. Furthermore, operation of the electrochemical cell in a stack arrangement of a PEM electrolyzer or a PEM fuel cell can be permitted at higher temperatures or pressures, which significantly improves the efficiency of such a stack arrangement. In particular, the solution proposed according to the invention allows an individual electrochemical cell within a stack arrangement to be sealed on both sides, i.e. on the cathode side and the anode side, according to the invention.Should the pressure conditions between the anode and cathode sides be reversed, a secure seal against leakage of the coated membrane and the media flowing through it is also guaranteed within the stack arrangement.

[0031] Since industrial fast or high-speed stacking, i.e. joining the porous structures into a cell frame or into a circumferential seal, would normally require a larger tolerance or lead-in chamfers or a high positioning effort, this effort can be significantly reduced in the embodiment according to the invention, since the sealing nose is applied to the porous structure perpendicular to the membrane plane during stacking.

[0032] In addition, a membrane that is overcoated in the coating area can be dismantled during reuse or repair. This can be replaced, for example, with a new component in the form of a coated membrane during a parts exchange. After reassembly, the repaired electrochemical cell can be reused within a stacked arrangement.

[0033] Short description of the drawings

[0034] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0035] Shown are: Figure 1 a section through an electrochemical cell,

[0036] Figure 2 shows the creep behavior of the coated membrane in a gap-shaped free space,

[0037] Figure 3 shows the coated membrane creeping into a free space with reversed pressure distribution compared to Figure 2,

[0038] Figure 4 shows a representation of critical areas,

[0039] Figure 5 shows the seals above and below the coated membrane in the area of ​​a media longitudinal channel,

[0040] Figures 6.1 - 6.3 the formation of circumferential sealing elements on seals designed as flat seals above the coated membrane,

[0041] Figure 7 shows the sealing elements on the seals on both sides of the coated membrane,

[0042] Figure 8 is a schematic representation of a stack arrangement of a PEM electrolyzer,

[0043] Figures 8.1 and 8.2 show different geometries of seals and porous transport structures in the areas on both sides of the membrane where they meet,

[0044] Figure 9 shows the geometry of a seal designed as a sealing cord,

[0045] Figure 10 shows the sealing body produced in a mold,

[0046] Figure 11 shows a top view of an exemplary molding tool with a serpentine-shaped recess for receiving the molding compound that forms the sealing cord. Figure 1 shows an electrochemical cell 10, which represents a single cell 12 and comprises a coated membrane 14. The membrane 14 comprises a top side 16 and a bottom side 18 and is provided on both sides with porous transport structures 20, 22. A cathode side is designated by reference numeral 24, while an anode side is designated by reference numeral 26. The porous transport structures 20, 22 on the cathode side 24 and the anode side 26 are each enclosed by a circumferentially formed first seal 28 and a second circumferentially formed seal 30, respectively. The seals 28, 30 can be provided with stiffening inserts 32.Due to manufacturing tolerances, gaps 34 arise between the porous transport structures 20, 22 and the surrounding seals 28, 30, which are designed here as flat gaskets. If the seals 28, 30 are compressed during assembly, the gap 34 closes if the dimensions are correct. However, the gussets in the area of ​​the edge breaks 54 of the gap 34 always remain open.

[0047] Figures 2 and 3 show that, due to the pressure level on a pressure side 38, the coated membrane 14 creeps into the gap 34 located between the second seal 30 and the porous transport structure 22 on the anode side. If the pressure conditions are reversed compared to Figure 2, then - as shown in Figure 3 - the coated membrane 14 creeps at its upper side 16 into the upper gap-shaped free space 34 between the first seal 28 and the porous transport structure 20 on the cathode side 24 of the electrochemical cell 10. The effects shown in Figures 2 and 3 are extremely detrimental to the service life of the coated membrane 14 and should therefore be avoided.

[0048] Figure 4 shows that the gaps or free spaces 34 occur, in particular, below the adjacent areas between the first seal 28 and the porous transport structure 20 and in the boundary area between the second seal 30 and the porous transport structure 22 on the underside 18 of the coated membrane 14.

[0049] Figure 5 shows that the creep 36 of the membrane 14 indicated in Figure 4 occurs in the region of a longitudinal media channel 42 in adjacent areas between the porous transport structure 20 on the cathode side 24 and the coated membrane 14, on the one hand, and on the underside 18 in adjacent areas between the second seal 30 and the porous transport structure 22 on the anode side 26, on the other hand. This occurs with a corresponding pressure distribution between the pressure side 38 and the low-pressure side 40.

[0050] Embodiments of the invention

[0051] In the following description of the embodiments of the invention, identical or similar elements are designated by the same reference numerals, whereby a repeated description of these elements is omitted in individual cases. The figures only schematically illustrate the subject matter of the invention.

[0052] From the sequence of Figures 6.1, 6.2 and 6.3 it can be seen that the first seal 28, which in this embodiment is designed as a flat seal, comprises a sealing element 46 in addition to the stiffening insert 32. The sealing element 46 according to Figure 6.1 can be designed as a circumferential sealing lip or as a circumferential sealing nose. Both the first seal 28 and the second seal 30, which here is also designed as a flat seal, run circumferentially around the porous transport structures 20, 22, which are located on the top side 16 and the bottom side 18, respectively, of the coated membrane 14, which has the flow field for the media. The seals 28, 30 are preferably made of flexibly deformable, elastic plastic material.

[0053] Figure 6.2 shows that a pressure distribution 48 is established in the gap-shaped free space 34 between the porous transport structure 20 and the first seal 28, which acts on the sealing element 46, whether designed as a circumferential nose or a circumferential lip. This forces the sealing element 46 against the upper side 16 of the coated membrane 14.

[0054] This can be seen in particular in the illustration according to Figure 6.3. Due to the deformability of the sealing element 46, the pressure level prevailing on the pressure side 38, i.e. on the cathode side 24 of the electrochemical cell 10, is sufficient to place the sealing element 46 in sealing contact 50 against the upper side 16 of the coated membrane 14. Figure 7 shows that in this embodiment of the first seal 28, designed here as a flat seal, and the second seal 30, also designed here as a flat seal with a stiffening insert 32, a circumferential sealing element 46 is formed. If the pressure conditions are reversed, as shown in connection with Figures 2 and 3 with regard to the coated membrane 14, the embodiment according to Figure 7 can be used to seal the coated membrane 14 on both sides against the gap-shaped free spaces 34.In this embodiment, too, the sealing elements 46, whether circumferential sealing noses or circumferential sealing lips, are made of deformable, elastic plastic material which, as shown in Figure 6.3, can be brought into sealing contact 50 on both sides, ie the top side 16 and the bottom side 18 of the coated membrane 14.

[0055] Figure 8 schematically shows a stack arrangement 52 of electrochemical cells 10 within a PEM electrolyzer. Alternatively, the stack arrangement 52 may also be one used in a PEM fuel cell.

[0056] Figures 8.1 and 8.2 show different geometries of boundary regions between the first seal 28 and the porous transport structure 20 on the upper side 16 of the coated membrane 14 and the second seal 30 and the porous transport structure 22 on the lower side 18 of the coated membrane 14.

[0057] Figure 8.1 shows that here, particularly on the underside 18 of the coated membrane 14, the second seal 30 as well as the porous transport structure 22 below the coated membrane 14 each have an edge break 54. The two edge breaks 54 of the mutually facing second seal 30 and the porous transport structure 22 on the anode side 26 form a wedge-shaped support surface 56. However, this is less deep than the gaps 34, as shown in connection with Figures 2 and 3, so that a significantly smaller deflection of the coated membrane 14 is possible due to the support surface 56 at a reduced depth. This can prevent cracking and excessive mechanical stress on the coated membrane 14. At the edge breaks 54, as shown in Figure 8.1, rounded portions 58 (cf. Figure 8.2) in the adjacent components of the first seal 28 and the porous transport structure 20 on the upper side 16 of the coated membrane 14. Furthermore, it is possible to form the adjacent regions of the seals 28, 30 or the porous transport structures 20, 22 in elliptical geometries 60. The schematic representation according to Figure 8.2 shows that the elliptical geometry 60 has a long semi-axis 62 and a short semi-axis 64. The surfaces corresponding to these are designed such that the surface of the long semi-axis 62 of the elliptical contour 60 points towards the surface of the first seal 28 and the surface of the short semi-axis 64 of the elliptical contour 60 points towards the surface of the coated membrane 14. The edge fractures 54 mentioned in connection with Figure 8.1 are in the order of magnitude of typical deformation values ​​of the coated membrane 14.Thus, a height 68 of the edge breaks 54 is in the range of up to 50% of a thickness 70 of the coated membrane 14, while a width 72 of the edge breaks 54 is one to ten times the height 68 of the edge breaks 54 in order to achieve good support. In general, a height 74 of the porous transport structure 20, 22 is between 50 pm and 5000 pm, in particular between 300 pm and 500 pm.

[0058] From the illustration in Figure 8, it can be seen that the edge break 54, on the one hand, and another edge break 66, on the other hand, form the wedge-shaped support surface 56. Depending on the inclination of the edge breaks 54, 66, a greater or lesser width 72 of the support surface 56 results.

[0059] The geometries shown in Figures 8.1 and 8.2, i.e. a gently inclined support surface 56, an elliptical geometry 60 or a rounding 58 of the adjacent areas of the components 20, 22, 28, 30, result in significantly lower creep possibilities for the deflection of the coated membrane 14 during operation of the electrochemical cell 10 due to the high pressure differences on both sides of the coated membrane 14. The solution proposed according to the invention can effectively limit the deflection of the coated membrane 14 both in the direction of the upper side 16 and in the direction of its underside 18, so that the mechanical stress on the coated membrane 14 is considerably reduced due to the pressure distribution.As a result, the service life of the electrochemical cells 10 accommodated in the stack arrangement 52 of a PEM fuel cell or a PEM electrolyzer can be significantly extended and the effectiveness of the operation of the stack arrangement 52 can be significantly improved.

[0060] The illustrations in Figures 9 and 10 show that the sealing element 28, 30 can also be manufactured as a sealing cord 86. A seal 28, 30 manufactured as a sealing cord 86 can be designed such that it has a flat side 82 on its upper side, which is delimited at least at one end by a nose-shaped projection forming a sealing element 46. The illustrations in Figures 9 and 10 show that a sealing body 80 of a sealing cord 86 has a substantially rectangular cross-section. The sealing elements 46 cast on both sides of the flat side 82 fill the areas at which the sealing element 46 designed as a sealing cord 86 borders, for example, on the porous transport structure 22 on the anode side 26, i.e. the underside 18 of the coated membrane 14.As shown in Figure 9, due to the geometry of the seal 28, 30 manufactured as a sealing cord 86, the gap or the free space 34, which extends according to Figures 2 and 3 to the porous transport structure 22 on the anode side 26 of the coated membrane 14, is effectively filled, so that the coated membrane 14 cannot deform due to the pressure gradient between the pressure side 38 and the low pressure side 40.

[0061] Figure 11 schematically shows that a molding tool 88 for producing a seal 28, 30 designed as a sealing cord 86 has a serpentine-shaped recess 90. The molding tool 88, as shown schematically in plan view in Figure 11, is closed by a flat cover, so that when the serpentine-shaped recesses 90 in the molding tool 88 are filled, the flat side 82 shown in Figure 10 is positioned on the top side of the sealing body 80. Due to the geometry of the serpentine-shaped recess 90 in the molding tool 88, the aforementioned sealing elements 46, which are here nose-shaped, are produced on the flat side 82, on one or both sides, directly during the manufacture of the sealing body 80.In a method for producing the sealing cord 86 as a deformable circumferential seal 28, 30 of an electrochemical cell 10, the following process steps are carried out: a) introducing a serpentine-shaped recess 90 into a molding tool 88, b) applying a flat cover to the serpentine-shaped recess 90 in the molding tool 88, which is filled with a molding compound, for molding a flat side 82 and sealing elements 46 adjacent thereto, and c) removing the endless sealing cord 86 with flat side 82 and the sealing elements 46 delimiting it from the molding tool 88.

[0062] The mold 88, which is only schematically shown in Figure 11, is not split in the middle; instead, the serpentine-shaped recess 90 is formed in one side of the mold, and a flat cover is placed on top for injection molding. This creates the aforementioned sealing elements 46 on both sides of the flat side 82. These sealing elements 46, here designed in a nose shape, can be used to fill the gap-shaped cavities 34 above and below the coated membrane 14.

[0063] The inventively proposed embodiments of seals 28, 30 designed as flat gaskets or sealing cords 86 allow for effective sealing of the electrochemical cell 10, particularly when accommodated in a stacked arrangement 52 of a PEM electrolyzer or a PEM fuel cell. Leakage of media, such as H2O, H2, or O2, can be prevented by the deformation of the sealing elements 46 due to the prevailing pressure conditions. This ensures that the media flow through the flow field of the coated membrane 14 and does not penetrate into other areas.

[0064] As described above, with contact surfaces 56 formed accordingly with rounded portions 58, elliptical geometries 60, or moderately inclined between the adjacent components, excessive deflection of the coated membrane 14 due to the prevailing pressure distribution between the cathode side 24 and the anode side 26 is eliminated, which significantly improves the service life of the electrochemical cell 10 proposed according to the invention and its operation. In particular, sharp-edged transitions, which could lead to cracking in the coated membrane 14, can be significantly avoided, which is extremely beneficial to the service life of the electrochemical cell 10 proposed according to the invention.

[0065] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, numerous modifications are possible within the scope of the claims, which are within the scope of one skilled in the art.

Claims

Claims 1. An electrochemical cell (10) of a stack arrangement (52) of a PEM electrolyzer or an AEM electrolyzer or a PEM fuel cell, comprising a plurality of electrochemical cells (10) which have porous transport structures (20, 22) on both sides of a coated membrane (14) on a cathode side (24) and an anode side (26) and which are sealed on both sides by seals (28, 30) within the stack arrangement (52), characterized in that gaps (34) resulting on both sides of the coated membrane (14) between the seals (28, 30) and the porous transport structures (20, 22) are at least partially filled by deformable sealing elements (46), in particular sealing noses or sealing lips, provided on the seals (28, 30).

2. Electrochemical cell (10) according to claim 1, characterized in that the seals (28, 30) are designed as flat seals or as sealing cord (86).

3. Electrochemical cell (10) according to claims 1 and 2, characterized in that the seals (28, 30) are provided with an insert (32) stiffening them.

4. Electrochemical cell (10) according to claims 1 to 3, characterized in that the seals (28, 30) are designed to run circumferentially around the porous transport structures (20, 22).

5. Electrochemical cell (10) according to claims 1 to 4, characterized in that the seals (28, 30) comprise deformable sealing elements (46), in particular sealing lips or sealing noses, facing the porous transport structures (20, 22).

6. Electrochemical cell (10) according to claim 5, characterized in that the sealing elements (46) facing the porous transport structures (20, 22) are deformable in such a way that they by a pressure distribution (48) in the gaps (34) to be sealed against an upper side (16) and / or a lower side (18) of the membrane (14) in contact (50).

7. Electrochemical cell (10) according to claims 1 to 6, characterized in that regions of the seals (28, 30) and / or the porous transport structures (20, 22) placed on an upper side (16) and / or a lower side (18) of the membrane (14) are designed as rounded portions (58) or in an elliptical geometry (60).

8. Electrochemical cell (10) according to claims 1 to 7, characterized in that the porous transport structures (20, 22) are provided with an edge break (54) which forms a support surface (56) with an edge break (54) of an adjacent seal (28, 30) or an edge break (54) forms a support surface (56) with a rounded portion (58) or two adjacent rounded portions (58).

9. Electrochemical cell (10) according to claim 8, characterized in that a height (68) of the edge break (54) is up to 50% of a thickness (70) of the membrane (14).

10. Electrochemical cell (10) according to claim 8, characterized in that a width (72) of the edge break (34) is one to ten times a height (68) of the edge break (54).

11. Electrochemical cell (10) according to claims 1 to 10, characterized in that the porous transport structures (20, 22) have a thickness between 50 pm to 2000 pm, in particular between 300 pm to 500 pm.

12. Electrochemical cell (10) according to claims 1 and 2, characterized in that seals (28, 30) designed as sealing cords (86) have a flat side (82) facing the membrane (14).

13. Electrochemical cell (10) according to claim 12, characterized in that the flat side (82) is provided with a sealing element (46) at least at one end.

14. Electrochemical cell (10) according to claim 7, characterized in that the elliptical geometry (60) is designed such that a surface on a long semi-axis (62) of the elliptical geometry (60) is assigned to the seals (28, 30) and a surface on a short semi-axis (64) of the elliptical geometry (60) is assigned to the membrane (14).

15. A method for producing a deformable circumferential seal (28, 30) designed as a sealing cord (86) for an electrochemical cell (10), comprising the following method steps: a) introducing a serpentine-shaped recess (90) into a molding tool (88); b) applying a flat cover to the serpentine-shaped recess (90) in the molding tool (88) filled with a molding compound for molding a flat side (82) and the sealing elements (46) adjacent to it; c) removing the sealing cord (86) with the flat side (82) and the sealing elements (46) adjacent to it from the molding tool (88).

16. Use of the electrochemical cell (10) according to one of claims 1 to 14 in a stack arrangement (52) of a PEM electrolyzer or an AEM electrolyzer or a PEM fuel cell.

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