Electrochemical cell with coated membrane

Abstract

The invention relates to an electrochemical cell (10) having a coated membrane (14), the upper side (16) of which or the lower side (18) of which is associated with at least one porous transport structure (20, 22), which is surrounded by a frame (28, 30). The frame (28, 30) is embodied in a frame under internal stress in such a way that the frame transitions from a vertical position (56) into an assembly position (58) during assembly, or the frame (28, 30) comprises a plurality of spring elements (60) provided with profiles (64), after the frame is assembled, the spring element transforms an inner wall (74) of the frame (28, 30) into a sealing contact (72) on the at least one porous transport structure (20, 22). The invention further relates to the use of the electrochemical cell (10) in a PEM electrolysis device (82) or a PEM fuel cell.

Description

Technical Field

[0001] The invention relates to an electrochemical cell having a coated membrane, the upper or lower side of which is assigned at least one porous transport structure, which is surrounded by a frame. Furthermore, the invention relates to the use of the electrochemical cell in a stack assembly of a PEM electrolyzer or a PEM fuel cell. Background Art

[0002] WO 18 / 196947 A1 (corresponding to AU 2017 411 874 A1) relates to a method for operating a water electrolysis device. In this electrolysis device, water from a PEM electrolysis device is conveyed 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 to the PEM electrolysis device again. The heat exchangers form secondary-side components of a common heat transfer circuit, which has a cooling device, and the heat transfer flow for controlling and / or regulating the temperature of the water conveyed to the ion exchanger and / or PEM electrolysis device partially or completely bypasses the cooling device.

[0003] PEM electrolyzers and PEM fuel cells, like heat exchangers, consist of stacked flat elements. Here, the flat elements form the anode-side chamber and cathode-side chamber with the selective separation membrane. The membrane should be similar to that of a PEM fuel cell; in a PEM electrolyzer, only positive ions, i.e., conventional H, are permitted. + The ions pass through to the cathode. The alkaline AEM electrolysis device is fed to the anode and / or cathode by an alkaline solution such as KOH. - In the case of alkaline AEM electrolysis, only anions, that is, OH - The ions pass through in the direction of the anode. For simplicity, the PEM electrolysis device will be explained below by way of example. When constructing a PEM electrolysis device, water is input into the anode-side chamber and water and oxygen are discharged. The chamber constructed on the cathode side preferably contains mostly the hydrogen formed. Preferably, the hydrogen chamber on the cathode side has a higher pressure, for example on the order of 30 bar, which is greater than the pressure acting in the anode-side chamber, on the order of 1 bar to 5 bar. The aforementioned chambers must be sealed from each other in the stack. Here, the sealing can be carried out by a sealing plate or a sealant applied to a flat surface or by a sealing tape in the form of an O-ring.

[0004] Flat seals require relatively high pressing forces and high material usage. Because in electrolytic cells or fuel cells, the active area is conventionally formed by a flow field (flow field) and conventionally by a porous structure, the goal is to connect the seal to the flow field without gaps to prevent reactants or products from flowing around the flow field through the gaps rather than through the flow field. Especially at interfaces or in the joint area, seals without gaps in the flow field, for example, are not always possible. Here, the diaphragm is pressed into the gap between the mutually opposing seals and the opposing flow field by the pressure difference described above. If, for example, an O-ring seal is used, the O-ring is conventionally constructed as a circle in terms of processing technology, that is, the O-ring has a circular cross-section and a circular main dimension. Therefore, a main dimension of the order of magnitude of the diameter is obtained, which must be matched to a relatively large mold in the injection molding process. In addition, even if the area inside the large seal is filled with many small seals to optimally utilize the die, a large machine with relatively high processing costs is required. Summary of the Invention

[0005] According to the solution of the present invention, an electrochemical cell is provided, comprising a coated membrane, to the upper or lower side of which at least one porous transporting structure is assigned, which is surrounded by a frame. The frame is designed to be under internal stress so that it is transferred from a vertical position into the assembled position during assembly, or the frame comprises a plurality of spring elements provided with shaped portions, which, after assembly of the frame, bring the inner wall of the frame into sealing contact with the at least one porous transporting structure.

[0006] By means of the solution proposed according to the invention, the sealing frame can advantageously be assembled without further sealing elements and a reliable seal of the at least one porous transport structure can be ensured immediately after assembly.

[0007] In an advantageous further development of the electrochemical cell according to the invention, the frame has a reinforcing lining that generates internal stress and is embedded in the elastic, flexibly deformable plastic material of the frame. This allows, on the one hand, the seal-forming frame to be imparted with the required internal stress, which, for example, enables breaking apart. On the other hand, the solution according to the invention allows for a tolerance-compensating and effective seal due to the flexibly deformable plastic material used.

[0008] In an advantageous further development of the electrochemical cell proposed according to the invention, the frame has a substantially trapezoidal cross section in the vertical position before its assembly.

[0009] In the electrochemical cell proposed according to the invention, the frame has a substantially rectangular cross section in its assembled position. No further sealing elements are required when transferring the frame from its vertical position into its sealing assembled position.

[0010] Within the scope of the solution proposed according to the invention, a sealing contact of the frame on the porous transmission structure is provided in its assembly position, so that on the one hand no further sealing elements are required and on the other hand the sealing contact also serves to compensate for manufacturing errors, so that manufacturing errors can be kept within a larger tolerance range, which has a beneficial effect on the manufacturing costs.

[0011] Alternatively, in the electrochemical cell proposed according to the invention, a plurality of spring elements can be embedded in the frame, the shaped parts of the spring elements exerting a prestress on the frame.

[0012] In a further development, both the frame and the seal are designed such that these elements have a slight projection, ie, an inclined position, so that the circumferential compression occurs by flattening the projection in the assembled state.

[0013] In an advantageous further development of this embodiment variant of the electrochemical cell according to the invention, it is possible for the spring element to be shaped, for example, in an S-shape or in a U-shape with two legs running parallel to one another.

[0014] In an advantageous further development of this embodiment variant of the electrochemical cell proposed according to the invention, the frame is provided with at least one projection on its inner wall, facing the at least one porous transport structure, by means of a spring element. This allows prestressing to be built into the frame before assembly.

[0015] In a variant embodiment proposed according to the invention, after the frame is assembled, at least one projection on the inner wall of the frame forms a sealing contact with the at least one porous transmission structure. The prestressing force generated in the frame by means of the spring element is maintained by the spring element provided with the shaped portion and, after the frame is assembled, is converted into a prestressing force that causes the inner wall of the frame to form a sealing contact with the at least one porous transmission structure.

[0016] In an advantageous embodiment of the electrochemical cell proposed according to the invention, a plurality of spring elements can be connected to the reinforcing lining of the frame.

[0017] In another advantageous embodiment of the electrochemical cell according to the invention, the frame and the at least one porous transport structure have edge notches or rounded corners on their mutually facing sides, which, in the assembled position, form support surfaces for the coated membrane. By suitably designing these support surfaces from the mutually contacting components to be sealed, excessive mechanical deflection of the coated membrane, particularly of a relatively thin design, can be avoided, thereby preventing cracking or mechanical damage.

[0018] Advantageously, in this embodiment variant, the support surface is embodied with a depth that is at most 50% of the thickness of the coated membrane and with a width that corresponds to 1 to 10 times the depth of the support surface.

[0019] In the electrochemical cell proposed according to the invention, the mutually facing regions of the frame and the at least one porous transport structure delimit the support surface by rounded corners or an oval geometry.

[0020] The invention also relates to the use of the electrochemical cell in a stack assembly of a PEM electrolyser or an AEM electrolyser or a PEM fuel cell.

[0021] Advantages of the invention

[0022] The various aspects of the solution proposed according to the invention—namely, the vertical frame that can be transformed into the assembly position, the frame provided with formed spring elements, the spring elements connected to the reinforcing lining, and the support surfaces formed by the edge recesses—allow for a highly effective seal to be formed between the inner wall of the frame surrounding the porous transport structure and the porous transport structure. Furthermore, the use of additional sealing elements can be avoided. The solution proposed according to the invention also allows for the most effective compensation of manufacturing-related tolerances, allowing for greater tolerances to be tolerated during the machining of the relevant components. This has a beneficial impact on manufacturing costs.

[0023] The solution proposed according to the present invention can reduce the gaps between the frames surrounding the porous frame structure caused by tolerances. Furthermore, due to the smaller tolerances and support surfaces, the solution proposed according to the present invention can effectively suppress creep of thin membranes in these free spaces due to operational compressive stresses. This prevents the formation of cracks in the delicate structure of the membrane. Furthermore, the reduced mechanical loads significantly improve the service life and, therefore, the service life and performance of the coated membrane.

[0024] The solution proposed according to the present invention also significantly extends the service life of the corresponding electrochemical cells housed in a PEM electrolyzer or PEM fuel cell stack. Furthermore, a thinner thickness of the coated membrane is permitted, since it is now subject to less mechanical load due to the reduced free space and the configured support surface, thus significantly improving the efficiency of the PEM stack of the PEM electrolyzer or PEM fuel cell. Furthermore, operation at higher temperatures is possible, thus significantly improving the efficiency of the PEM fuel cell or PEM electrolyzer.

[0025] In the solution proposed according to the present invention, on the one hand, the frame structure can be clamped to a certain extent from its vertical position into the assembly position and, due to the soft, elastically deformable plastic material of the frame, rests sealingly against the outer edges of the porous structure, thereby achieving this sealing contact. On the other hand, if spring elements provided with shaped portions are embedded in the elastically deformable plastic material of the frame, their shaped portions can achieve a targeted distribution of preload on the porous transport structure both before and after the frame is assembled. The shaped portions of the individual spring elements within the elastically deformable plastic material of the frame ensure that, after assembly, the inner wall of the frame rests sealingly against the outer edges of the porous transport structure. Furthermore, according to the present invention, it is possible to connect the spring elements to a reinforcing lining integrated into the elastically deformable plastic material and, for example, to design the spring elements in a U-shape. The special configuration of the legs of such a U-shaped spring element also allows for a targeted distribution of preload before and after assembly of such a frame, particularly maintaining the preload in the sealing contact area on the outer edges of the porous transport structure.

[0026] Furthermore, the solution proposed according to the present invention makes it possible to provide edge notches between the frame and the porous transport structure in the areas where these components abut one another. These edge notches form support surfaces when joined together. The support surfaces, bounded by edge notches or rounded corners or elliptical rounded portions, limit the mechanical deflection of the extremely thin coated membrane, thus specifically limiting the mechanical loads caused by pressure differences in the electrochemical cell. This significantly extends the service life and effectively counteracts cracking that may occur, for example, in the flow field of the coated membrane. Consequently, the service life of such coated membranes used in PEM electrolyzers or PEM fuel cell stacks is significantly extended.

[0027] For industrial fast or high-speed stacking, that is, to integrate the porous structure into the battery frame or the surrounding seal, larger tolerances or introduction bevels or high positioning costs are usually required, so these costs can be significantly reduced in the case of implementation according to the invention because the sealing nose rests on the porous structure perpendicularly to the membrane plane during the stacking process.

[0028] Furthermore, within the scope of reuse, the solution proposed according to the invention allows the coated membrane to be reused with little or no deformation. This makes it possible to replace a severely deformed or otherwise damaged sealing membrane with a new one by disassembling it during reuse or reprocessing of an electrochemical cell, and to reassemble and continue to use the electrochemical cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Embodiments of the present invention are further explained with reference to the accompanying drawings and the following description.

[0030] The accompanying drawings show:

[0031] Figure 1 : cross section through the electrochemical cell,

[0032] Figure 2 : Schematic diagram of the creep behavior of a coated membrane in free space in the form of a gap,

[0033] Figure 3 : Arrangement of the trapezoidally deformed frame (solid line) on the porous frame structure and its transition to the assembly / pressing position (dashed line),

[0034] Figure 4 and 5 : The arrangement of an S-shaped spring element embedded in an elastically deformable plastic material before and during assembly of the porous transmission structure,

[0035] Figure 6 and 7 : U-shaped configuration of the spring element connected to the reinforcing lining of the frame before and after assembly on the porous transmission structure,

[0036] Figure 8 : Schematic illustration of a stack assembly of a PEM electrolyser,

[0037] Figure 8.1 and 8.2 : Different configurations of the support surface delimited by edge notches, rounded corners or partially elliptical geometries.

[0038] Figure 1An electrochemical cell 10 is shown, which is a single cell 12 and includes a coated membrane 14. The membrane 14 comprises an upper side 16 and a lower side 18 and is provided with porous transport structures 20, 22 on both sides. The cathode side is designated by reference numeral 24, while the 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 surrounded by a first frame 28, which is designed all around, or by a second frame 30, which is designed all around. The frames 28, 30 can be provided with a reinforcing lining 32. Due to manufacturing tolerances, free spaces 34 arise between the porous transport structures 20, 22 and the frames 28, 30, which surround them and are designed here as flat surface seals.

[0039] Depend on Figure 2 It can be seen that the coated membrane 14 creeps due to the pressure level on the pressure side 38 into the free space 34 between the second frame 30 and the porous transmission structure 22 on the anode side 26. Figure 2 If the pressure conditions are reversed, the coated membrane 14 creeps on its upper side 16 into the gap-shaped free space 34 located above, between the first frame 28 and the porous transport structure 20 on the cathode side 24 of the electrochemical cell 10. Figure 2 The effects shown in are disadvantageous with regard to the service life of the coated membrane 14 and are therefore to be avoided. DETAILED DESCRIPTION

[0040] In the following description of exemplary embodiments of the present invention, identical or similar elements are identified with the same reference numerals, wherein a repeated description of an element is omitted in individual cases. The figures merely schematically illustrate the subject matter of the present invention.

[0041] Figure 3 A first embodiment variant of an electrochemical cell 10 proposed according to the invention, designed in a schematic manner as an individual cell 12 , is shown.

[0042] If according to Figure 3 As can be seen from the schematic diagram of FIG, the first frame 28 is assembled in a vertical direction 54 by applying an assembly force 52 to the porous transport structure 20 (cathode) shown schematically here. Figure 3 Starting from the vertical position 56 shown in FIG, the first frame 28 is transferred into the assembly position 58 by the action of the assembly force 52. In the vertical position 56, the first frame 28 provided with the reinforcing lining 32 for generating internal stress has a substantially trapezoidal cross section. Figure 3 In the trapezoidal cross section shown in solid lines, the assembly force 52 acts in the assembly direction so that the first frame 28 is assembled on the porous transport structure 20 (cathode) and assumes the position 58 thereof. Figure 3The substantially rectangular cross section is shown in dashed lines. In its assembled position 58, the inner wall 74 of the first frame 28 and the wall of the porous transport structure 20 (cathode) are in contact with each other. This results in a sealing contact 72, since tolerances are compensated by the elastically deformable plastic material of the first frame 28, into which a reinforcing metal lining 32, for example made of metal, is embedded. For example, according to Figure 3 , the first frame 28 is mounted on the cathode side 24 on the porous transport structure 20 (cathode), but can equally well be - as in the attached Figure 1 and 2 - mounted on the underside 18 of the coated membrane 14, surrounding and sealing the porous transport structure 22 (anode). Figure 3 As can be seen from the schematic diagram of FIG, no further sealing elements are required to achieve a sealing contact 72 between the inner wall 74 of the first frame 28 and the outer edge of the porous transport structure 20 (cathode). The sealing contact 72 is achieved solely by deformation of the first frame 28 from its vertical position 56 into the assembled position 58.

[0043] Depend on Figure 4 and 5 It can be seen that the first frame 28 includes a plurality of spring elements 60 in addition to the reinforcing lining 32. Figure 4 The cross-sectional view of the first frame 28 shows only one of the spring elements 60 provided with a profile 64. The profile 64 can be as shown in FIG. Figure 4 As shown in FIG, for example, it is constructed as an S-shape 66. By the S-shaped direction of the shaped portion 64, according to Figure 4 In the cross-sectional view of , the lower region of the inner wall 74 of the first frame 28 is enlarged in such a way as to form a projection 76. In this position of the first frame 28, the porous transport structure 20 (cathode) is assembled in the vertical direction 54 by applying an assembly force 52.

[0044] Figure 5 As shown, due to the S-shape 66 of the at least one spring element 60, when assembling the porous transport structure 20 (cathode), according to Figure 4The protrusion 76 disappears and the S-shaped shape 66 of the at least one spring element 60 shifts in the deflection direction, so that in the region above the S-shaped shape 66 of the at least one spring element 60, the protrusion 76 abuts the outer edge of the porous transport structure 20 (cathode) as a sealing abutment 72, thereby forming a sealing abutment 72. This means that the gap formed below the protrusion 76 between the inner wall 74 of the first frame 28 and the gap generated at the outer edge of the porous transport structure 20 (cathode) is sealed from above. This results in a sealing abutment 72 that not only seals but also compensates for errors. This allows for greater tolerances in the manufacturing of the porous transport structure 20 (cathode), as these errors can be compensated due to the deformability of the elastic material of the first frame 28, which is provided with the spring elements 60 embedded in the elastically deformable plastic material. This higher tolerance in manufacturing can result in cost savings.

[0045] according to Figure 6 and 7 Another embodiment of the electrochemical cell 10 according to the present invention and its sealing part can be seen in the sequence of figures of FIG. Figure 4 , the porous transport structure 20 (cathode) is mounted in the first frame 28 along the vertical direction 54. In this embodiment variant, the first frame 28 is provided with the aforementioned reinforcing lining 32, which can be made of metal material, for example. Figure 6 and 7 In the embodiment variant of the invention, the spring element 60 is connected to the reinforcing lining 32 via a web, and in such a configuration the spring element has a shaped portion 64 in the form of a U-shape 68. The U-shape 68 of the shaped portion 64 is characterized in that it has two legs 70 running essentially parallel to each other. Figure 6 In the illustration of FIG, a projection 76 is produced by the lower leg 70 on the inner wall 74 of the first frame 28 .

[0046] Once based on Figure 7 The porous transport structure 20 (cathode) is assembled along the vertical direction 54, then initially according to Figure 6 The projection 76 present in the lower region of the inner wall 74 is deformed due to the deformation of the spring element 60 created in the U-shape 68 so that, as in Figure 7 In the upper region of the inner wall 74 of the first frame 28, a sealing contact 72 is produced on the outer edge of the porous transport structure 20 (cathode). Figure 5 , in this embodiment variant, the free space 34 which is optionally produced between the inner wall 74 of the first frame 28 on the one hand and the edge of the porous transport structure 20 (cathode) on the other hand is also sealed against the ingress of media.

[0047] according to Figures 4 to 7The embodiment variant makes it possible to "snap" or "snap" the porous transport structure 20 (cathode) into the first frame 28, which is pre-deformed accordingly by the protrusion 76, due to the action of the assembly force 52. Figure 5 and Figure 7 Once the porous transport structure 20 (cathode) has reached its assembly position 58 , the first projection 76 comes into sealing contact 72 due to the deflection of the shaped portion 64 of the spring element 60 embedded in the elastically deformable plastic material of the first frame 28 .

[0048] Figure 8 A stack assembly 80 of a PEM electrolyzer 82 is shown schematically. The stack assembly 80 can be similarly configured for a PEM fuel cell, but in Figure 8 The PEM fuel cell is not shown. Figure 8.1 and 8.2 Different embodiment variants of the support surface 88 can be seen.

[0049] The support surface 88 is located above or below the coated membrane 14. Figure 8.1 As can be seen, the coated membrane 14 is embodied, for example, with a thickness of 94. A first frame 28 and the porous transport structure 20 (cathode) adjoining it are located on the upper side 16 of the coated membrane 14. A second frame 30 and the porous transport structure 22 (anode) are located opposite one another on the lower side 18 of the coated membrane 14. The porous transport structure 22 (anode) has an edge notch 84 on its upper side. This edge notch is located opposite another edge notch 86 in the edge region of the second frame 30. If the two edge notches 84 and 86 abut one another, as in Figure 8.1 As shown, a support surface 88 is generated. The corresponding edge notches 84, 86 are of the order of magnitude of the typical deformation values ​​of the coated membrane 14. The depth 92 of the support surface 88 is, for example, at most 50% of the thickness 94 of the coated membrane 14, while the width 90 of the support surface 88 corresponds to 1 to 10 times the depth 92 of the support surface 88. Figure 8 The illustrated geometry prevents excessive mechanical deformation of the sensitive coated diaphragm 14 and thus cracking or mechanical pre-damage due to the pressure gradient existing between the low-pressure sides 40 of the electrochemical cells 10, which are configured here as individual cells 12. The geometry of the support surface 88 also prevents the coated diaphragm 14 from creeping into gaps or free spaces 34, which could form due to manufacturing-related tolerances and could impair the service life or durability of the coated diaphragm 14 and the flow field configured thereon.

[0050] Depend on Figure 8.2It can be seen that instead of the support surface 88 formed by the edge notches 84, 86, a radius 96 or an elliptical geometry 98 can also be implemented in the edge region of adjacent components, for example the first frame 28 and the porous transport structure 20 (cathode) or the second frame 30 and the porous transport structure 22 (anode) adjacent to the second frame. The elliptical geometry 98 of such an edge region of the above-mentioned components is formed by a major semi-axis 100 or a minor semi-axis 102, which can delimit the corresponding support surface 88, as shown in the example of Figure 8.1 The support surfaces are shown in FIG as edge notches 84, 86. Due to the rounded contour of the support surface 88 in the mutually adjacent edge regions of the first frame 28 and the porous transport structure 20 (cathode) on the one hand and the second frame 30 and the porous transport structure 22 (anode) on the other hand, excessive mechanical deformations when the coated membrane 14 is subjected to loads can be at least significantly limited.

[0051] The invention is not limited to the embodiments described herein and the aspects highlighted therein. Instead, numerous modifications within the scope of the person skilled in the art are possible within the scope of the claims.

Claims

1. An electrochemical cell (10) comprising a coated membrane (14), the upper side (16) or the lower side (18) of the membrane being assigned at least one porous transport structure (20, 22), the porous transport structure being surrounded by a frame (28, 30), characterized in that: The frame (28, 30) is designed as a frame under internal stress so that during assembly it is transferred from a vertical position (56) into an assembled position (58), or The frame (28, 30) comprises a plurality of spring elements (60) provided with shaped portions (64), which, after the frame is assembled, bring an inner wall (74) of the frame (28, 30) into sealing contact (72) with the at least one porous transport structure (20, 22).

2. The electrochemical cell (10) according to claim 1, characterized in that The frame (28, 30) has a reinforcing lining (32) which generates the internal stress and is embedded in the elastic, flexibly deformable plastic material of the frame (28, 30).

3. The electrochemical cell (10) according to claim 1, characterized in that The frame (28, 30) has a substantially trapezoidal deformed cross section in the vertical position (56) before assembly.

4. The electrochemical cell (10) according to claim 1, characterized in that The frame (28, 30) has a substantially rectangular cross section in its assembled position (58).

5. The electrochemical cell (10) according to claim 1, characterized in that In the assembled position (58) of the frame (28, 30), a sealing contact (72) is produced on the at least one porous transporting structure (20, 22).

6. The electrochemical cell (10) according to claim 1, characterized in that A plurality of spring elements (60) are embedded in the frame (28, 30), wherein the shaped portions (64) of the spring elements cause the spring elements (60) to project within the frame (28, 30).

7. The electrochemical cell (10) according to claim 6, characterized in that The shaped portion (64) of the spring element (60) is embodied in an S-shape (66) or in a U-shape (68) having two legs (70) running parallel to one another.

8. The electrochemical cell (10) according to claims 6 to 7, characterized in that A projection (76) is implemented in the frame (28, 30) and is capable of being brought into contact with the at least one porous transport structure (20, 22) via the spring element (60).

9. The electrochemical cell (10) according to claims 6 to 8, characterized in that After the frame (28, 30) is assembled, at least one projection (76) on the inner wall (74) of the frame interior (28, 30) forms a sealing contact (72) on the at least one porous transport structure (20, 22).

10. The electrochemical cell (10) according to claims 6 to 9, characterized in that The plurality of spring elements (60) are connected to the reinforcing lining (32) of the frame (28, 30).

11. The electrochemical cell (10) according to claims 1 to 10, characterized in that The frame (28, 30) and the at least one porous transport structure (20, 22) have edge notches (84, 86) or rounded corners facing each other on their sides, which form a support surface (88) for the coated membrane (14) in the assembly position (58).

12. The electrochemical cell (10) according to claims 1 to 11, characterized in that The support surface (88) is embodied with a depth (92) that is at most 50% of the thickness (94) of the coated membrane (14) and with a width (90) that corresponds to 1 to 10 times the depth (92) of the support surface (88).

13. The electrochemical cell (10) according to claims 1 to 10, characterized in that The mutually facing areas of the frame (28, 30) and the at least one porous transport structure (20, 22) are delimited by a support surface (88) formed by rounded corners (96) or an elliptical geometry (98).

14. Use of the electrochemical cell (10) according to any one of claims 1 to 13 in a stack assembly (80) of a PEM electrolysis device (82) or a PEM fuel cell.

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