Membrane Electrode Assembly and Fuel Cell, Electrolyzer, Electrochemical Hydrogen Compressor, Redox Flow Battery or Electrochemical Sensor Comprising the Membrane Electrode Assembly

Abstract

The present invention relates to a membrane electrode assembly (10, 20, 30), comprising: a cathode (6c), an anode (6a), a proton conducting membrane (6b) arranged between the cathode (6c) and the anode (6a), and a sealing frame, wherein the sealing frame surrounds the cathode (6c), the anode (6a) and the membrane (6b) at their edges, wherein at least the superposed local areas (9) of the cathode (6c), the anode (6a) and the membrane (6b) are exposed in an inner area (8) of the sealing frame, and the sealing frame comprises a first sealing layer (1) and a second sealing layer (2) along a layer thickness direction (S), wherein the first sealing layer and the second sealing layer are connected to each other by an adhesive (3), and the first sealing layer (1) and / or the second sealing layer (2) have a reinforcing structure (4).

Description

Technical Field

[0001] The present invention relates to a membrane electrode assembly with improved sealing and a fuel cell, an electrolyzer, an electrochemical hydrogen compressor, a redox flow battery or an electrochemical sensor having such a membrane electrode assembly. Background Art

[0002] For electrochemical applications, such as fuel cells, water electrolysis, and electrochemical sensors, membrane electrode assemblies (MEAs, also called membrane electrodes) include a proton-conducting membrane arranged between an anode and a cathode. To prevent reactant gases from unintentionally escaping from the MEA or from unintentionally reaching the cathode from the anode side or vice versa, and to facilitate the use of the MEA and conserve layer material, the MEA is typically surrounded by a frame-shaped seal. This frame-shaped seal also extends the service life of the MEA by preventing direct contact between the gas diffusion layers on both sides of the MEA and the MEA. EP 2 089 930 A2 describes a membrane electrode assembly having a sealing frame comprising an upper plastic film and a lower plastic film, wherein the plastic films are connected to each other by an adhesive layer. A disadvantage of the sealed MEA described in EP 2 089 930 A2 is that the adhesive in the bonding layer is susceptible to creep under MEA operating conditions, resulting in rheological and shrinkage properties in the bonding layer. This thinning of the frame-shaped seal in the MEA edge region significantly reduces the sealing performance. Since hundreds of MEAs are used in a membrane electrode stack, this thinning results in significant dimensional variations within the stack, limiting both power density and service life. Summary of the Invention

[0003] Based on this prior art, the object of the present invention is to provide a membrane electrode assembly having a sealing frame that is characterized by particularly low shrinkage, creep, and rheological properties at normal operating pressures and temperatures. Furthermore, the object of the present invention is to provide a fuel cell, electrolyzer, electrochemical hydrogen compressor, redox flow battery, or electrochemical sensor having such a membrane electrode assembly that is characterized by a consistently high power density and, therefore, a very long service life.

[0004] This object is achieved by a membrane electrode assembly according to the present invention, which includes: a cathode; an anode; a proton-conducting membrane arranged between the cathode and the anode; and a sealing frame, which surrounds the cathode, anode and membrane at their edges, wherein in the internal area of the sealing frame, at least the upper and lower overlapping local areas of the cathode, anode and membrane are exposed, wherein the sealing frame includes a first sealing layer and a second sealing layer in the layer thickness direction, the first sealing layer and the second sealing layer are connected to each other by an adhesive, and the first sealing layer and / or the second sealing layer have a reinforced structure.

[0005] This object is therefore achieved by a membrane electrode assembly comprising: a cathode; an anode; a proton-conducting membrane disposed between the cathode and the anode; and a specially designed sealing frame. The sealing frame is configured to surround the cathode, anode, and membrane at their edges. This means that the cathode, anode, and membrane are surrounded on all sides at their edges by a frame-shaped seal.

[0006] A frame-shaped seal or sealing frame, in the sense of the present invention, refers to a sealing structure that is constructed like a picture frame and has a free inner area between the corresponding inner edges of the sealing frame, which is shaped like a picture or window-like cutout. In this inner area, at least the superimposed partial areas of the cathode, anode and membrane are exposed and are therefore not covered by the sealing frame. In this case, the sealing frame can only be connected to the edges of the cathode, anode and membrane at their respective peripheries, or the cathode, anode and / or membrane partially overlap along the layer thickness direction of the MEA, that is, along the arrangement direction of the layers of the MEA. The layer thickness direction also corresponds to the stacking direction of the MEA, that is, to the arrangement direction of the anode, membrane and cathode.

[0007] The sealing frame includes a first sealing layer and a second sealing layer along the layer thickness direction, and these sealing layers are connected to each other by an adhesive. The adhesive is in contact with both the first sealing layer and the second sealing layer. In addition, the first sealing layer and / or the second sealing layer also have a reinforcement structure. The reinforcement structure can be present in a local area of the first and / or second sealing layer, or distributed over the entire first and / or second sealing layer. The reinforcement structure is characterized by a high retention capacity for the adhesive. More precisely, the reinforcement structure prevents the adhesive from creeping or flowing out of the sealing frame. As a result, the shrinkage of the MEA is suppressed, and the MEA is also characterized by a high power density and, therefore, a long service life in conventional use.

[0008] According to an advantageous development, the reinforcement structure is constructed in the first sealing layer and / or the second sealing layer. This means that the reinforcement structure is not used as a separate layer, but is directly formed into the first sealing layer and / or the second sealing layer and is therefore an integral component of the first sealing layer and / or the second sealing layer. For example, the corresponding reinforcement structure can be applied or sprayed onto the surface of the sealing layer, for example by plastic injection molding or thermoforming. Possible reinforcement structures can also be extruded. As an alternative, the reinforcement structure can also be formed in the following way, that is, local areas of the sealing layer are recessed, so that such non-recessed local areas are characterized by raised structures. The recesses can be formed, for example, by mechanical processing of the sealing layer surface, for example by pressing, stamping or compacting. In particular, the raised structure can be processed by pressing into a roller equipped with a female mold of the raised structure, wherein the roller is particularly heated. This embodiment has the advantage that there is no need to provide additional layers for the reinforcement structure, and the corresponding reinforcement structure can be directly integrated into the first and / or second sealing layer according to the size of the sealing layer. In this case, it is sufficient to arrange the reinforcement structure in one sealing layer. However, the reinforcing structure can also be formed in the first and second sealing layer.

[0009] In order to obtain the above-mentioned sealing layer with an integrated reinforcement structure, according to another preferred embodiment, the first side of the first and / or second sealing layer can have a raised structure. Here, the first side of the first and / or second sealing layer refers to the side or surface of the corresponding sealing layer facing the first side of the corresponding second or first sealing layer in the MEA. Here, the raised structure has a height greater than 3 μm, preferably greater than 10 μm and particularly preferably greater than 15 μm. The raised structure is formed on the surface of the first side, and the height of the raised structure is measured from this surface to the highest point of the raised structure in the layer thickness direction, that is, to the highest point perpendicular to the circumferential direction of the sealing frame. By constructing the raised structures, gaps or in other words grooves are formed between the raised structures, which accommodate the adhesive and prevent creep or outflow. The corresponding second side of the first and / or second sealing layer with the raised structure on the first side is flat here, with neither raised structures nor grooves. These raised structures and grooves are only formed on the first side.

[0010] The raised structure further advantageously includes separators, which are in particular designed to be linear, L-shaped, T-shaped or cross-shaped. This makes it possible to easily and effectively form a retaining structure for the adhesive that can be well adapted to the dimensions of the sealing frame. In this case, the separators in particular have a width of 5 μm to 5 mm, preferably 50 μm to 500 μm, and a length of 10 μm to 10 mm, preferably 100 μm to 1 mm. The width of the separator refers to the shortest side, and the length of the separator refers to the longest side, with both the length and width of the separator being perpendicular to the height of the separator. These dimensions make it particularly easy to retain the desired amount of adhesive in the sealing frame and prevent it from creeping or flowing away.

[0011] Due to the good capture and thus good retention of the adhesive, the spaces between the raised structures are preferably square, rectangular, circular or hexagonal. This means that the raised structures are configured so that recessed areas, or in other words, grooves or spaces, are formed between them, which are square, rectangular, circular or hexagonal. Combinations of these space shapes are also possible.

[0012] In addition, for good dimensional stability of the adhesive and therefore particularly good suppression of creep behavior or flow-off of the adhesive, the volume percentage of the voids present between the raised structures relative to the total volume of the voids and the raised structures is 10% to 99%, preferably 12% to 80% and more preferably 15% to 70%. The higher the volume percentage of the voids, the more adhesive can be locally bonded. The lower the volume percentage of the voids, that is, the higher the volume percentage of the raised structures, the more stable the sealing layer can be constructed. In order to have a good stability of the sealing layer while having a high adhesive retention capacity, a volume percentage of voids of 15% to 50% has been found to be particularly advantageous. Here, the term "void volume percentage" refers to the sum of the volumes of all voids formed in the sealing layer.

[0013] According to another advantageous embodiment, the first sealing layer and / or the second sealing layer comprises a carrier film and a reinforcement structure in the form of a reinforcement layer. In other words, this means that the respective sealing layer (i.e. the first sealing layer, the second sealing layer or the two sealing layers) is constructed as at least two layers and comprises a carrier film and a reinforcement layer in contact with the carrier film. In this case, the carrier film can be connected to the reinforcement layer, for example by a lamination process. However, the reinforcement layer can also be connected to the surface of the carrier film in other ways, wherein, for example, such an adhesive connection can be formed by an adhesive. Mechanical joining, such as by a form-locking and / or force-locking connection, is also possible. In this case, the reinforcement layer is arranged on the carrier film of the first and / or second sealing layer in such a way that it faces in the direction of the respective second or first sealing layer. This embodiment has the advantage that providing the reinforcement structure in the form of a reinforcement layer is very simple and economical and that the reinforcement layer can be easily stored.

[0014] In this embodiment, the reinforcement structure preferably includes a woven structure and / or a porous structure and / or a perforated structure. Woven structures can be economically produced according to the desired mesh size and structure. Woven structures can be produced using polymer filaments. Polymer filaments are characterized by yarn diameter, while fabrics are characterized by the number of weft and warp yarns, the weave pattern, and the resulting total thickness. In particular, the total thickness can be reduced by hot extrusion, or calendering, at the intersections of the warp and weft yarns. Calendering also helps fuse the warp and weft yarns, thereby increasing the fabric's stability and improving its processability. Porous structures have openings of more or less irregular sizes, or so-called pores, that can accommodate adhesives. These can be produced, in particular, by axially or biaxially stretching a film. Perforated structures, on the other hand, are produced, for example, by perforation using a knife, perforator, needle, or laser. All holes (pores, perforations, fabric through-holes, etc.) provided in the reinforcement structure have in common that they completely penetrate the reinforcement layer in the thickness direction and therefore lead from the first side of the reinforcement layer to the second side. This is a key difference from sealing layers with raised structures, which always have a closed base layer whose height along the layer thickness does not count towards the height of the raised structure. In the embodiment shown here, the carrier film forms a closed base layer. The porous, woven, or perforated reinforcement structure allows the adhesive to penetrate into the reinforcement layer, or more precisely, to fill and impregnate the reinforcement layer with the adhesive of the sealing frame. This spatially confined adhesive, and its softening under high pressure and temperature—as in membrane electrode assembly applications—does not lead to adhesive flow, effectively preventing shrinkage and thinning of the MEA in the edge region.

[0015] Particularly stable and readily available reinforcement structures preferably contain fibers (particularly carbon fibers), metal meshes, porous ceramic materials, or polymers, particularly materials selected from the group consisting of polyolefins, polyesters, aromatic polymers, (per)fluorinated polymers, polysiloxanes, or mixtures thereof. The polymer reinforcement structure can be porous, perforated, or woven. Porous polymer structures can be produced, for example, by polymer foaming. Alternatively, the polymer can be present as a mesh fabric, as is well known, for example, in the screen printing field, in which the individual polymer fibers have a specific yarn diameter. The size of the individual mesh openings, or mesh size, is determined by the yarn diameter and the number of yarns (i.e., the number of threads per length). The weave pattern can also vary, with plain or Panama weaves being particularly common. Furthermore, the fabric can be calendered, which, on the one hand, achieves greater stability by connecting the warp and weft threads at their intersections, as these threads can no longer slip. On the other hand, by compressing the round yarn diameters into an oval shape, the overall thickness is reduced. This also reduces the open area, ie, the volume percentage of through-holes formed in the reinforcement layer.

[0016] The volume percentage of through-pores (such as pores, perforations, or fabric through-pores) formed in the reinforcement layer, relative to the total volume of the reinforcement layer, is advantageously 10% to 99%, preferably 12% to 80%, and more preferably 15% to 70%. In this case, the through-pore size distribution can be determined according to the Barrett-Joyner-Halenda (BJH) method in accordance with DIN 66134:1998-02 - Determination of Pore Size Distribution and Specific Area of Mesoporous Solid Materials by Nitrogen Absorption. This method is particularly suitable for determining the through-pore volume percentage of porous structures. For perforations, the through-pore volume percentage is calculated directly from the perforation geometry, i.e., from the perforation diameter and the number of perforations per unit area. For fabrics, the through-pore volume percentage is similarly calculated from the yarn diameter and the number of yarns. This allows the calculation of the yarn volume (the yarn cross-sectional area and the yarn length in a cell, where a cell is defined from yarn to yarn).

[0017] In order to strengthen the structure of the MEA, according to an advantageous development, the inner area of the reinforcement layer is larger than the inner area of the carrier film. In other words, this means that the framed or window-shaped cutout of the reinforcement layer is larger than the framed or window-shaped cutout of the carrier film. In this case, the window-shaped cutout of the reinforcement layer can be larger than or equal to the area of the membrane electrode assembly, so that the reinforcement layer and the membrane electrode assembly have no overlapping area, or the window-shaped cutout of the reinforcement layer can be smaller than the area of the membrane electrode assembly, so that the reinforcement layer and the membrane electrode assembly have an overlapping area. If the window-shaped cutout of the reinforcement layer is larger than or equal to the area of the membrane electrode assembly, the mechanical stress of the membrane electrode assembly is reduced because the total thickness in the overlapping area of the membrane electrode assembly and the carrier film is smaller. Thus, in terms of long-term stability and gas tightness, it can be advantageous if the reinforcement layer and the membrane electrode assembly have no overlapping area.

[0018] In order to provide the sealing frame with particularly good temperature stability, the reinforcement structure advantageously has a softening temperature of greater than 75° C., preferably greater than 90° C., further preferably greater than 105° C., particularly preferably greater than 120° C., and further preferably greater than 160° C. The corresponding softening temperature can be achieved by suitable selection of the material depending on the desired temperature stability, in particular depending on the typical application of the MEA.

[0019] To provide the membrane with particularly high sealing and insulating properties, it can further be advantageous to provide that the first and / or second sealing layers overlap the anode and / or cathode and / or membrane to form an overlapping region. This means, for example, that the overlapping local region of the anode, cathode, and membrane is larger than the internal area of the sealing frame. Consequently, the local region of the anode, cathode, and membrane is particularly clamped between the first and second sealing layers, thereby achieving particularly high stability for the MEA.

[0020] For ease of production, the sealing frame overlaps the anode, cathode, and membrane, in particular in the same section or region. This allows the stacked anode, membrane, and cathode assembly to be trimmed in a single step to create a corresponding overlapping region with the sealing frame.

[0021] According to another advantageous development, the thickness of the adhesive layer is at least as great as the sum of the heights of the raised structures in the first and second sealing layers. This means that the adhesive is also present only in the gaps or recesses between the raised structures and can be flush with the upper sides of the raised structures. In this case, the reinforcing structure is saturated with the adhesive. If only the first sealing layer contains the raised structures, the upper sides of the raised structures of the first sealing layer and the adhesive are in direct contact with the second sealing layer.

[0022] If both the first sealing layer and the second sealing layer have raised structures, the adhesive is present in the corresponding gaps or grooves of the corresponding sealing layers and is flush with the corresponding upper sides of the raised structures in the corresponding sealing layers, so that the adhesive present in the gaps of the first sealing layer is connected to both the second sealing layer and the adhesive present in the gaps of the second sealing layer. Similarly, the adhesive present in the gaps of the second sealing layer is connected to both the first sealing layer and the adhesive present in the gaps of the first sealing layer.

[0023] By means of this embodiment, good contact between the first and second sealing layers can be formed via the adhesive, thereby also achieving good stability of the overall composite structure.

[0024] As a further alternative, it is advantageous to provide that the thickness of the adhesive layer is at least as great as the thickness of the reinforcement layers present in the first and second sealing layers. As has been repeatedly stated, the layer thickness is measured along the layer thickness direction or stacking direction of the MEA. The reinforcement layer may also be present only in the first sealing layer, only in the second sealing layer, or in both sealing layers. If the reinforcement layer is present in only one sealing layer, the adhesive layer is flush with the top side of the reinforcement layer. This also applies to both sides if the reinforcement layer is present in the first and second sealing layers.

[0025] In both embodiments described above, the adhesive is present at least and advantageously only in the reinforcement structure, so that creep and outflow behavior are suppressed to the greatest extent possible.

[0026] According to another advantageous development, a glue layer composed of an adhesive is located between the first and second sealing layers. This glue layer consists solely of adhesive and, viewed in the layer thickness direction, is located between the first and second sealing layers. The glue layer therefore contains no reinforcement. To provide particularly good protection against flow away or creep, the glue layer preferably has a thickness of less than 30 μm, in particular less than 20 μm, and in particular less than 10 μm.

[0027] In order to simplify the fabrication of the MEA of the present invention, the anode and cathode are directly applied to the membrane and form a catalyst coated membrane (CCM).

[0028] The membrane electrode assembly further advantageously comprises a first gas diffusion layer arranged on the surface of the anode facing away from the membrane and a second gas diffusion layer arranged on the surface of the cathode facing away from the membrane. In this case, gas through holes for conveying reaction gases can also be provided in the sealing frame.

[0029] The membrane electrode assembly of the present invention can be manufactured in various ways, including the following non-limiting examples:

[0030] First, in a preliminary step, the reinforcement structure, in the form of a reinforcement layer, is connected to the first sealing layer. The sealing layer preferably comprises an adhesive, in the form of at least one adhesive layer. This connection can be achieved, for example, in a single lamination step using pressure and heat. Once the adhesive layer has softened due to heating, the reinforcement structure is then filled or impregnated by applying pressure. Subsequently, exposed internal areas, in the form of window-like cutouts, are created in the first and second sealing layers by cutting or punching. In this process, the first and second sealing layers and the reinforcement structure have identical dimensions.

[0031] Furthermore, a membrane electrode assembly (MEA) comprising a cathode, an anode, and a membrane located between the cathode and anode, and in particular configured as a CCM and provided as a sheet, is bonded to first and second sealing layers in such a manner that the MEA completely fills the window-like cutouts in the sealing layers, and a circumferential overlap region is achieved between the MEA and the first and second sealing layers. The MEA and the first and second sealing layers are bonded to one another by thermally activating or UV-treating the at least one adhesive layer, thereby achieving a stable, highly gas-tight bond. In particular, the adhesive layer can be activated under pressure to improve filling or impregnation of the reinforcement structure.

[0032] In an alternative second process flow, window-like cutouts are made in the first and second sealing layers and in the reinforcement structure. The window-like cutouts in the reinforcement structure can be larger than or equal to the window-like cutouts in the first and second sealing layers. In a subsequent step, the first and second sealing layers, the reinforcement structure, and a membrane-electrode assembly (MEA) as defined above (which is also advantageously configured as a CCM) are arranged relative to one another in such a manner that the MEA completely fills the window-like cutouts in the first and second sealing layers, thereby forming a circumferential overlap region between the MEA and the first and second sealing layers. The window-like cutouts in the reinforcement structure can be larger than or equal to the area of the MEA, resulting in no overlap between the reinforcement structure and the MEA, or smaller than the area of the MEA, resulting in an overlap region between the reinforcement structure and the MEA. All components are then connected to one another by thermally activating the at least one adhesive layer or subjecting it to UV treatment. In particular, the adhesive layer can be activated under pressure to improve filling or impregnation of the reinforcement structure.

[0033] The advantage of the second process flow lies in the flexibility in the size of the window-shaped cutout between the first and second sealing layers and the reinforcement structure. Furthermore, in terms of continued stability and gas tightness, it can be advantageous if the reinforcement layer and the membrane electrode assembly have no overlapping areas. Furthermore, the reinforcement structure can be arranged particularly symmetrically between the first and second sealing layers.

[0034] In the final step, the gas diffusion layer (GDL) can be attached to the membrane electrode assembly (MEA) with the sealing frame. The GDL (gas diffusion layer) can be attached, for example, using a heat-activated or UV-activated adhesive in the edge region or bonded to the surface of the MEA by lamination. The GDLs on the anode and cathode sides can be identical or different.

[0035] Likewise, the present invention also relates to a fuel cell, an electrolyzer, an electrochemical hydrogen compressor, a redox flow battery or an electrochemical sensor comprising the membrane electrode assembly disclosed above, thereby having the characteristics of high power density and long service life in conventional use. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Further details, advantages and features of the present invention are obtained from the following description of exemplary embodiments with reference to the accompanying drawings. The drawings show:

[0037] Figure 1 is a scanning electron microscope image of a cross section of a sealing frame of an MEA according to the first embodiment;

[0038] Figure 2 is a layer system of an MEA according to a second embodiment;

[0039] Figure 3 is a layer system of an MEA according to a third embodiment;

[0040] Figure 4 is a layer system of an MEA according to a fourth embodiment;

[0041] Figure 5 is a schematic diagram of a sealing layer having an elevated structure according to a fifth embodiment;

[0042] Figure 6 is a schematic diagram of a sealing layer having an elevated structure according to a sixth embodiment;

[0043] Figure 7 is a schematic diagram of a sealing layer having an elevated structure according to a seventh embodiment;

[0044] Figure 8 is a schematic diagram of a sealing layer having an elevated structure according to an eighth embodiment;

[0045] Figure 9 is a schematic diagram of a sealing layer having an elevated structure according to a ninth embodiment;

[0046] Figure 10 is the shrinkage of the sealing frame of the example.

[0047] In the accompanying drawings, only the main features of the present invention are shown. For the sake of clarity, all other features are omitted. In addition, the same reference numerals mark the same components / assemblies. DETAILED DESCRIPTION

[0048] Example

[0049] The following example diagrams illustrate the fabrication and shrinkage of a sealing frame for a membrane electrode assembly.

[0050] Example 1

[0051] The sealing frame produced according to Example 1 includes a first sealing layer and a second sealing layer, each of which is provided with an adhesive in the form of an adhesive layer, each of which has a nominal layer thickness of 15 μm. The reinforcing structure included in the sealing frame is composed of a reinforcing layer composed of a woven polyethylene terephthalate (PET) material with a layer thickness of 43 μm and a through-pore volume percentage of 15.1%. The number of warp and weft yarns is 180 cm and 180 cm, respectively, when the yarn diameter is 27 μm. -1 This results in a volume percentage of 52% of the adhesive to be filled relative to the total volume of the fabric, or a layer thickness of 22.4 μm to be filled.

[0052] Example 2

[0053] The sealing frame produced according to Example 2 includes a first sealing layer and a second sealing layer, each of which is provided with an adhesive in the form of an adhesive layer, each of which has a nominal layer thickness of 15 μm. The reinforcement structure is composed of a reinforcement layer consisting of a woven polyethylene terephthalate (PET) material with a layer thickness of 42 μm and a through-pore volume percentage of 28.6%. The number of warp and weft yarns is 150 cm, respectively, with a yarn diameter of 27 μm. -1 This results in a volume percentage of 59% of adhesive to be filled relative to the total volume of the fabric, or a layer thickness of 24.8 μm to be filled.

[0054] Example 3

[0055] The sealing frame produced according to Example 3 includes a first sealing layer and a second sealing layer, each of which is provided with an adhesive in the form of an adhesive layer, each of which has a nominal layer thickness of 15 μm. The reinforcement structure is composed of a reinforcement layer consisting of a woven material of polyetheretherketone (PEEK) with a layer thickness of 50 μm and a through-pore volume percentage of 58%. The number of warp and weft yarns is 73 cm and 100 mm, respectively, for a yarn diameter of 38 μm. -1 or 52cm-1 This results in a volume percentage of 72% of the adhesive to be filled relative to the total volume of the fabric, or a layer thickness of 35.8 μm to be filled.

[0056] Comparative Example 1

[0057] The sealing frame produced according to Comparative Example 1 is a composite body consisting of a first and a second sealing layer, each provided with an adhesive in the form of a 15 μm thick adhesive layer, but without a reinforcement structure.

[0058] Measurement of contractility

[0059] To determine the shrinkage of the sealing frames of Examples 1 to 3 and Comparative Example 1 (see the table below for details), the respective composites of the sealing frame layers, consisting of the first and second sealing layers, were placed in an apparatus capable of adjusting to a defined pressure. The pressure was set to 6.67 MPa, and the apparatus was heated to 95°C for 72 hours. The thickness of the composites was measured using a scanning electron microscope at an unpressurized area and a pressurized area. The difference in thickness corresponds to the shrinkage.

[0060]

[0061] Figure 10 A comparison of the shrinkage of the sealing frame of Comparative Example 1 and the sealing frame of Example 1 is shown. This comparison shows that by using the reinforcement structure in Example 1, a significant reduction in shrinkage can be achieved.

[0062] Figure 1 A scanning electron microscope cross-section of an MEA 100 according to a first embodiment is shown. The first sealing layer is designated by reference numeral 1, and the second sealing layer by reference numeral 2. The first and second sealing layers 1 and 2 are connected to each other by adhesive 3. Furthermore, a reinforcement structure, designated by reference numeral 4, is provided in the form of a fabric, i.e., a reinforcement layer, and is surrounded by adhesive 3. Adhesive 3 penetrates through the pores of the fabric. Reference numeral 5' denotes the first carrier film of the first sealing layer 1, and reference numeral 5" denotes the second carrier film of the second sealing layer 2.

[0063] The sealing frame is produced by applying an adhesive 3 in the form of an adhesive layer to two carrier films 5' and 5", respectively. The fabric is then placed on the adhesive layer of the first carrier film 5', and the carrier films 5', 5" are arranged relative to each other with their adhesive layers and pressed together under pressure and temperature, so that a firm composite is formed in the sealing frame.

[0064] Figure 2 by Figure 2 2a, 2b and 2c show the layer system of an MEA 10 according to a second embodiment. Figure 2 a schematically shows that in the layer system of MEA 10, the first sealing layer 1 comprises a first carrier film 5' and an adhesive 3 in the form of an adhesive layer. The second sealing layer 2 comprises a second carrier film 5" and a reinforcement structure 4 in the form of a reinforcement layer, in particular a textile. The first sealing layer 1 and the second sealing layer 2 are arranged relative to each other in such a way that the reinforcement structure 4 faces the adhesive layer. Figure 2 b shows a detailed top view of the first sealing layer 1 .

[0065] A window-like or picture-like cutout 7 is provided in the first sealing layer 1, which forms an exposed inner region 8' of the first sealing layer 1. Similarly, a window-like or picture-like cutout 7' is provided in the second sealing layer 2, which forms an exposed inner region 8' of the second sealing layer 2. The window-like cutouts 7 and 7' form a frame-like structure of the first and second sealing layers 1 and 2, which has an exposed inner region 8 of the sealing frame.

[0066] Reference numeral 6 denotes a catalyst-coated membrane 6 (CCM), which comprises a membrane 6b arranged between an anode 6a and a cathode 6c. The CCM is arranged between the first and second sealing layers 1, 2 such that, after the layers of the layer system have been connected, at least the superimposed partial regions 9 of the cathode, anode, and membrane are exposed in the inner region 8 of the sealing frame. Furthermore, an overlap region 11 is formed around the layers of the MEA 10, in which partial regions of the CCM 6 overlap the first and second sealing layers 1, 2.

[0067] The reinforcement structure 4 is provided for receiving an adhesive 3 which impregnates the reinforcement structure 4, as in Figure 2 As shown in FIG. 3 , after the layers of the layer system have been connected, the first sealing layer 1 and the second sealing layer 2 are permanently and firmly bonded to form a stable sealing frame, and the adhesive 3 is held in the reinforcing structure in a creep-proof, flow-proof and leak-proof manner.

[0068] Figure 2 c shows Figure 2 Figure a shows the layer system after bonding of the individual layers. The first and second sealing layers 1, 2 are connected to each other via an adhesive 3, wherein the adhesive 3 penetrates and impregnates the reinforcement structure 4, thereby forming a stable sealing frame on the one hand and preventing creep and flow under the operating conditions of the membrane electrode assembly 10 on the other.

[0069] Figure 3 a to 3c as Figure 2 2a to 2c show the layer systems for producing the individual layers of the membrane electrode assembly 20 ( Figure 3 a) A top view of the first sealing layer 1 ( Figure 3 b) and MEA 20 according to a third embodiment, the MEA comprising Figure 3 The layer system shown in a is formed. Figure 2 The first and second sealing layers 1, 2 are different, Figure 3 The first and second sealing layers are configured such that the window-shaped cutouts of the reinforcement structure 4 are larger than the window-shaped cutouts of the carrier films 5 ′, 5 ″.

[0070] Figure 4 a to 4c as Figure 2 2a to 2c, like 3a to 3c, show the layer systems for producing the individual layers of the membrane electrode assembly 30 ( Figure 4 a) A top view of the first sealing layer 1 ( Figure 4 b) and MEA30 according to the fourth embodiment ( Figure 4 c) The MEA consists of Figure 4 The layer system shown in a is formed. Figure 2 and 3 Different, in Figure 4 In the layer system of a, there are two adhesive layers consisting of adhesives 3 and 3', which are arranged on a first carrier film 5' and a second carrier film 5", respectively, wherein one reinforcement structure is first prepared as a loose layer with window-like cutouts and is loosely connected to the CCM 6. After the layers are pressed, a structure is formed as in Figure 4 MEA30 shown in c.

[0071] Figure 5 A schematic diagram shows in detail an exemplary first sealing layer 1 having a reinforcement structure 4 in the form of a plurality of raised structures 12 according to a fifth embodiment, wherein Figure 5 a shows a top view, Figure 5 b shows a cross-sectional view along A:A, and Figure 5 c shows a cross-sectional view along line B:B. The reinforcement structure is formed in the first sealing layer 1 and is therefore an integral component of the first sealing layer 1. Due to the formation of the raised structure 12, the area of the first sealing layer 1 around the raised structure has a smaller height, thus forming a gap 13 or groove.

[0072] The raised structures 12 are formed in the form of linear separators and have a height h greater than 3 μm, preferably greater than 10 μm and particularly preferably greater than 15 μm. The raised structures 12 are formed on the surface 14 of the first side 15 of the first sealing layer 1, where (cf. Figure 5b) The height h of the raised structures 12 is measured starting from this surface, more precisely to the highest point of the raised structures 12 in the layer thickness direction S. The second side 16 of the first sealing layer 1 is free of raised structures and is flat. This forms a flat section of the first sealing layer, which is designated as the base layer 17 and has a height h1, which provides the sealing structure with high dimensional stability.

[0073] In this case, the separator has, in particular, a width y of 5 μm to 5 mm, preferably 50 μm to 500 μm, and a length x of 10 μm to 10 mm, preferably 100 μm to 1 mm. As shown here, the width of the separator refers to the shorter side, while the length of the separator refers to the longest side, wherein both the length and width of the separator are perpendicular to the height of the separator.

[0074] As in Figure 5 As shown in Figure 1a, the separators are arranged one behind the other along their length x in parallel rows R1, R2, R3, and R4. In each row R1 to R4, the separators are arranged one behind the other in the longitudinal direction at a corresponding distance w. The distance between two adjacent rows R1 to R4 is referred to as z. Typical values for y and z are 5 μm to 5 mm, and preferably 50 μm to 500 μm. Typical values for w and x are 10 μm to 10 mm, and preferably 100 μm to 1 mm.

[0075] As in Figure 5 As shown in FIG, since the raised structures 12 are designed as separators, gaps 13, or in other words, grooves, are formed between the raised structures 12, which can accommodate the adhesive and prevent creep or outflow. By using a first sealing layer 1 as shown here, thinning of the sealing frame can be prevented, thereby achieving high and permanently reliable stability in the membrane electrode assembly.

[0076] Figure 6 by Figure 6 6a, 6b and 6c show schematic views of a first sealing layer 1 having a raised structure 12 according to a sixth embodiment.

[0077] and Figure 5 The elevated structure 12 shown is different. Figure 6 The raised structure 12 shown is constructed in an L-shape. The L-shaped structure can be divided into two substructures, namely a Figure 5 The illustrated embodiment shows a linear substructure 18 and a substructure 19 arranged perpendicular thereto. The linear substructure 18 also has a length x and a width y. The perpendicular substructure 19 has a length y2 and a width x2. Typical values for y and z are 5 μm to 5 mm, preferably 50 μm to 500 μm. Typical values for w, x, x2, and y2 are 10 μm to 10 mm, preferably 100 μm to 1 mm.

[0078] By Figure 6 The raised structures 12 shown in the figure are designed as L-shaped separators, with gaps 13 (grooves) formed between them to accommodate the adhesive and prevent creep or outflow. The use of a first sealing layer 1 as shown here also prevents thinning of the sealing frame, thereby achieving high and permanently reliable stability in the membrane electrode assembly.

[0079] Figure 7 by Figure 7 7a, 7b and 7c show schematic views of a first sealing layer 1 having a raised structure 12 according to a seventh embodiment.

[0080] and Figure 5 The elevated structure 12 shown is different. Figure 7 The raised structure 12 shown is constructed as a cross. This cross is regularly constructed and can be divided into a plurality of substructures, i.e., a Figure 5 The linear substructure 18 shown and the two identical substructures 19 arranged perpendicular thereto also have a length x and a width y. The substructure 19 extending perpendicular thereto has a length y2 and a width x2. Typical values for y and z are 5 μm to 5 mm, preferably 50 μm to 500 μm. Typical values for w, x, x2, and y2 are 10 μm to 10 mm, preferably 100 μm to 1 mm.

[0081] By Figure 7 The raised structures 12 shown in the figure are designed as cross-shaped separators. Interspaces 13 (grooves) are also formed between these raised structures 12 to accommodate adhesive and prevent creep or outflow. The use of a first sealing layer 1 as shown here also prevents thinning of the sealing frame, thereby achieving high and permanently reliable stability in the membrane electrode assembly.

[0082] Figure 8 Detailed diagram of the first sealing layer 1 is shown, which has an elevated structure 12 according to the eighth embodiment. Figure 5 Like the raised structure 12 shown, Figure 8 The raised structures 12 shown are also configured as linear dividers and are arranged in rows R1, R2, and R3, except that in each row R1 to R3, each second linear raised structure 12a (i.e., every other raised structure), i.e., each second divider, is arranged perpendicularly to the preceding and following linear raised structures 12. The respective centers of the perpendicularly arranged linear raised structures 12a lie on the longitudinal axes of the linear raised structures 12 that are arranged successively in the row.

[0083] The separators are designed to be identical in length and width, specifically having a width y of 5 μm to 5 mm, preferably 50 μm to 500 μm, and a length x of 10 μm to 10 mm, preferably 100 μm to 1 mm. The separators are arranged in rows R1-R3, spaced one behind the other at corresponding distances w in the longitudinal direction of the linear raised structures 12. The distance between two adjacent rows R1-R3 is referred to herein as z. Typical values for y and z are 5 μm to 5 mm, preferably 50 μm to 500 μm. Typical values for w and x are 10 μm to 10 mm, preferably 100 μm to 1 mm.

[0084] By Figure 8 The raised structures 12 shown here are designed as straight separators arranged perpendicular to one another. Interspaces 13 (grooves) are also formed between these raised structures 12, which can accommodate adhesive and prevent creep or outflow. The use of a first sealing layer 1 as shown here also prevents thinning of the sealing frame, thereby achieving high and consistently reliable stability in the membrane electrode assembly.

[0085] Figure 9 by Figure 9 9a, 9b and 9c are schematic diagrams showing a first sealing layer 1 having a raised structure 12 according to a ninth embodiment. Different from the first sealing layer 1 described above, Figure 9 The first sealing layer 1 shown in FIG is constructed such that the reinforcement structures are formed into interconnected rectangles, wherein the voids 13 located within the interior of the rectangles have an inverted pyramidal structure. Each rectangle has a length x3 and a width y3, measured at the inner edges of the rectangle formed by the raised structures 12. In this case, w3 is the width of the raised structure 12 between two longitudinally adjacent rectangles, and z3 is the width of the raised structure 12 between two transversely adjacent rectangles.

[0086] Will Figure 9 The raised structures 12 shown in FIG. 4 are designed in a rectangular form, thereby forming a "closed" reinforcement structure 4 having raised structures 12 on its outer edges. Recesses 13 (grooves) are formed in the corresponding rectangular interiors, allowing adhesive to be received in the reinforcement structure 4 and thus preventing creep or outflow. The use of a first sealing layer 1 as shown here also prevents thinning of the sealing frame, thereby achieving high and permanently reliable stability in the membrane electrode assembly.

[0087] In addition to the above written description of the present invention, the present invention is also described in the accompanying Figures 1 to 9 The features disclosed in also explicitly belong to the disclosure content of the present invention.

[0088] Reference Signs List

[0089] 1. First sealing layer

[0090] 2 Second sealing layer

[0091] 3 Adhesive

[0092] 4 Enhanced structure

[0093] 5' First carrier film of the first sealing layer

[0094] 5” Second carrier film for the second sealing layer

[0095] 6 Catalyst Coated Membrane (CCM)

[0096] 6a Anode

[0097] 6b membrane

[0098] 6c cathode

[0099] 7 Window-like incision

[0100] 8 Inner area of the sealing frame

[0101] 8' Inner area of the first sealing layer

[0102] 8” internal area of the second seal layer

[0103] 9. Exposed local areas of the anode, cathode, and membrane arranged in overlapping layers

[0104] 10, 20, 30, 100 membrane electrode assembly (MEA)

[0105] 11 Overlapping Area

[0106] 12 Elevated Structure

[0107] 12a Second linear elevated structure

[0108] 13 Gap

[0109] 14 Surface of the first side of the sealing layer

[0110] 15 First side of the sealing layer

[0111] 16 Second side of the sealing layer

[0112] 17 Grassroots

[0113] 18 Linear substructure

[0114] 19 Vertical substructure

[0115] h Height of the raised structure

[0116] h1 height of the base layer

[0117] x The length of the separator

[0118] y-divider width

[0119] x2 Width of the vertically extending substructure of the L-shaped separator

[0120] y2 Length of the vertically extending substructure of the L-shaped separator

[0121] w is the distance of the separator along the longitudinal direction of the separator

[0122] x3 Width of the raised structure

[0123] y3 width of the adjacent rectangle

[0124] w3 Width of the raised structure 12 along the length x3 of the adjacent rectangle

[0125] S layer thickness direction

Claims

1. A membrane electrode assembly (10, 20, 30), comprising: cathode (6c); Anode (6a); a proton conducting membrane (6b) disposed between the cathode (6c) and the anode (6a); and A sealing frame encloses a cathode (6c), an anode (6a) and the membrane (6b) at its edges, wherein at least superposed local areas (9) of the cathode (6c), the anode (6a) and the membrane (6b) are exposed in an inner area (8) of the sealing frame, wherein the sealing frame comprises a first sealing layer (1) and a second sealing layer (2) along a layer thickness direction (S), the first sealing layer and the second sealing layer being connected to each other by an adhesive (3), and the first sealing layer (1) and / or the second sealing layer (2) having a reinforcing structure (4).

2. The membrane electrode assembly (10, 20, 30) according to claim 1, wherein the reinforcement structure (4) is formed in the first sealing layer (1) and / or in the second sealing layer (2).

3. The membrane electrode assembly (10, 20, 30) according to claim 2, wherein, in order to obtain the reinforcement structure (4), the first side (15) of the first sealing layer (1) and / or the second sealing layer (2) has a raised structure (12), which first side faces the first side (16) of the corresponding second sealing layer (2) or the first sealing layer (1), and the raised structure has a height (h) greater than 3 μm.

4. The membrane electrode assembly (10, 20, 30) according to claim 3, wherein the elevated structure has a height (h) greater than 10 μm.

5. The membrane electrode assembly (10, 20, 30) according to claim 4, wherein the elevated structure has a height (h) greater than 15 μm.

6. The membrane electrode assembly (10, 20, 30) of claim 3, wherein the elevated structure (12) comprises a separator. 7 . The membrane electrode assembly ( 10 , 20 , 30 ) according to claim 6 , wherein the separators are designed to be linear, L-shaped, T-shaped or cross-shaped.

8. The membrane electrode assembly (10, 20, 30) according to claim 6 or 7, wherein the separator has a width (y) of 5 μm to 5 mm and a length (x) of 10 μm to 10 mm.

9. The membrane electrode assembly (10, 20, 30) according to claim 8, wherein the separator has a width (y) of 50 μm to 500 μm and a length (x) of 100 μm to 1 mm.

10. The membrane electrode assembly (10, 20, 30) according to any one of claims 3 to 7, wherein the gaps (13) between the raised structures (12) are rectangular, circular or hexagonal.

11. The membrane electrode assembly (10, 20, 30) according to any one of claims 3 to 7, wherein the gaps (13) between the raised structures (12) are square.

12. The membrane electrode assembly (10, 20, 30) according to claim 3, wherein the volume percentage of the voids (13) existing between the elevated structures (12) relative to the total volume of the voids (13) and the elevated structures (12) is 10% to 99%.

13. The membrane electrode assembly (10, 20, 30) according to claim 3, wherein the volume percentage of the voids (13) existing between the elevated structures (12) relative to the total volume of the voids (13) and the elevated structures (12) is 12% to 80%.

14. The membrane electrode assembly (10, 20, 30) according to claim 3, wherein the volume percentage of the voids (13) existing between the elevated structures (12) relative to the total volume of the voids (13) and the elevated structures (12) is 15% to 70%.

15. The membrane electrode assembly (10, 20, 30) according to claim 1, wherein the first sealing layer (1) and / or the second sealing layer (2) comprises a carrier film (5', 5") and a reinforcement structure (4) in the form of a reinforcement layer.

16. The membrane electrode assembly (10, 20, 30) according to claim 15, wherein the reinforcement structure (4) comprises a woven structure and / or a porous structure and / or a perforated structure.

17. The membrane electrode assembly (10, 20, 30) according to claim 16, wherein the reinforcement structure (4) comprises fibers, metal mesh, porous ceramic material or polymer.

18. The membrane electrode assembly (10, 20, 30) according to claim 17, wherein the reinforcement structure (4) comprises carbon fibers.

19. The membrane electrode assembly (10, 20, 30) according to claim 17, wherein the reinforcement structure (4) comprises a polymer selected from the group consisting of polyolefins, polyesters, aromatic polymers, (per)fluorinated polymers, polysiloxanes or mixtures thereof.

20. The membrane electrode assembly (10, 20, 30) according to claim 15 or 16, wherein the volume percentage of the through holes formed in the reinforcement layer relative to the total volume of the reinforcement layer is 10% to 99%, and / or the inner area of the reinforcement layer is larger than the inner area of the carrier film.

21. The membrane electrode assembly (10, 20, 30) according to claim 20, wherein the volume percentage of the through holes formed in the reinforcement layer relative to the total volume of the reinforcement layer is 12% to 80%.

22. The membrane electrode assembly (10, 20, 30) according to claim 21, wherein the volume percentage of the through holes formed in the reinforcement layer relative to the total volume of the reinforcement layer is 15% to 70%.

23. The membrane electrode assembly (10, 20, 30) according to any one of claims 1 to 7, wherein the reinforcement structure (4) has a softening temperature greater than 75°C, and / or The first sealing layer (1) and / or the second sealing layer (2) overlap with the anode (6a) and / or the cathode (6c) and / or the membrane (6b) and form an overlapping region (11).

24. The membrane electrode assembly (10, 20, 30) according to claim 23, wherein the reinforcement structure (4) has a softening temperature greater than 90°C.

25. The membrane electrode assembly (10, 20, 30) according to claim 24, wherein the reinforcement structure (4) has a softening temperature greater than 105°C.

26. The membrane electrode assembly (10, 20, 30) according to claim 25, wherein the reinforcement structure (4) has a softening temperature greater than 120°C.

27. The membrane electrode assembly (10, 20, 30) according to claim 26, wherein the reinforcement structure (4) has a softening temperature greater than 160°C.

28. The membrane electrode assembly (10, 20, 30) of claim 23, wherein a sealing frame overlaps the anode (6a), cathode (6c) and the membrane (6b).

29. The membrane electrode assembly (10, 20, 30) according to claim 28, wherein the sealing frame overlaps the anode (6a), the cathode (6c) and the membrane (6b) on the same parts.

30. A membrane electrode assembly (10, 20, 30) according to any one of claims 3 to 7, wherein the thickness of the adhesive layer consisting of the adhesive (3) is at least as great as the sum of the heights (h) of the raised structures (12) in the first sealing layer and the second sealing layer, or at least as great as the thickness of the reinforcing structure (4) in the form of a reinforcing layer present in the first sealing layer and the second sealing layer.

31. The membrane electrode assembly (10, 20, 30) according to any one of claims 3 to 7, wherein a pure glue layer formed by an adhesive (3) is present between the first sealing layer (1) and the second sealing layer (2), and the pure glue layer has a layer thickness of less than 30 μm, and / or wherein the anode (6a) and the cathode (6c) are directly attached to the membrane (6b) and form a catalyst-coated membrane, and / or Furthermore, it comprises a first gas diffusion layer arranged on the side of the anode (6a) facing away from the membrane (6b) and a second gas diffusion layer arranged on the side of the cathode (6c) facing away from the membrane (6b).

32. The membrane electrode assembly (10, 20, 30) according to claim 31, wherein the pure glue layer has a layer thickness of less than 20 μm.

33. The membrane electrode assembly (10, 20, 30) according to claim 32, wherein the pure glue layer has a layer thickness of less than 10 μm.

34. A fuel cell, an electrolyser, an electrochemical hydrogen compressor, a redox flow battery or an electrochemical sensor comprising the membrane electrode assembly (10, 20, 30) according to any one of claims 1 to 33.

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