Electrochemically active unit for electrochemical device

Abstract

In order to provide an electrochemically active unit for an electrochemical device, the electrochemically active unit comprising a membrane-electrode assembly, at least one gas diffusion layer, and a sealant joined to at least one of the at least one gas diffusion layer, such that when manufacturing such an electrochemically active unit, a permeation region can be formed as uniformly as possible along the perimeter of the gas diffusion layer, in which permeation region the gas diffusion layer of the electrochemically active unit is permeated by the sealant material of the sealant, it is proposed that the sealant comprises a joining region, a distribution region, and a connecting region connecting the joining region and the distribution region to each other, wherein the connecting region has a minimum height (hc) that is less than one quarter of the maximum height (H V ) of the distribution region and less than one quarter of the maximum height (H A ) of the joining region.

Description

Technical Field

[0001] The invention relates to an electrochemically active cell for an electrochemical device, wherein the electrochemically active cell comprises a membrane-electrode arrangement, at least one gas diffusion layer and a seal which is connected to at least one of the at least one gas diffusion layers. Background Art

[0002] Such electrochemically active units can form, together with a bipolar plate in each case, an electrochemical cell of an electrochemical device which is designed, for example, as a fuel cell stack or an electrolyzer.

[0003] The electrochemical device preferably comprises a plurality of electrochemical cells arranged one above the other in the stacking direction and preferably two end plates. The stack of electrochemical cells is arranged between the two end plates and can be clamped relative to each other by means of a clamping device, so that a clamping force along the stacking direction is applied to the electrochemical cells arranged between them and in particular their electrochemically active units.

[0004] In fuel cell stacks and electrolyzers, different media are conducted in different planes of the electrochemical cells and, depending on the design, also in different regions of the same plane. These media can be, in particular, anode fluid (fuel gas), cathode fluid (oxidant) and possibly also fluid coolant.

[0005] The medium (cathode fluid, anode fluid, coolant) delivered to the electrochemical device is delivered to different planes of the electrochemical device or discharged from different planes of the electrochemical device by a medium distribution structure (also called "manifold") having a medium delivery channel and a medium discharge channel extending in the stacking direction of the electrochemical device, and must be delivered from the medium delivery channel to the flow field (Flow Field) of the relevant medium in the electrochemical cell, and discharged from the flow field to the medium discharge channel again. Here, not only the medium delivery channel and the medium discharge channel but also the flow field are sealed, thereby preventing leakage to the external space of the electrochemical device, and preventing leakage between spaces through which different media flow.

[0006] The media passing through the electrochemical device must neither mix with each other nor escape from the electrochemical cell, so sealing is required in multiple planes.

[0007] These seals can be realized, for example, on the basis of elastomeric materials and / or adhesive bonding.

[0008] In electrochemical cells having metallic bipolar plates, sealing may be achieved completely or partially by crimping or elastomeric based seals in the bipolar plates.

[0009] The bipolar plate (also called separator or interconnector) can be constructed in one piece or comprise at least two individual layers (bipolar plate layers).

[0010] The bipolar plate layers of the multi-layer bipolar plate can be connected to each other by a splicing method, such as welding or bonding.

[0011] The seal can be inserted as a separate component into the stack of electrochemical cells or can be fastened to a bipolar plate or another component of the electrochemical cell, for example to a gas diffusion layer or a membrane-electrode arrangement.

[0012] Due to the advantages in handling and manufacturing and due to the simple sealing design, it is usually preferred to fix the seal on the bipolar plate. This can be done, for example, by injecting the seal, especially made of an elastomeric material, onto the layer of the bipolar plate.

[0013] In this seal configuration, it has proven to be advantageous to combine a seal fixed to the bipolar plate with an edge reinforcement device fixed to the membrane-electrode device (in particular a catalyst-coated membrane, CCM) in the edge region of the membrane-electrode device, wherein the edge reinforcement device serves as a counterpart to the seal, helps prevent adverse mechanical loads on the membrane-electrode device and at the same time ensures that the electrochemically active area of ​​the membrane-electrode device is advantageously connected to the edge region of the membrane-electrode device.

[0014] Such an edge reinforcement is known, for example, from EP 1 403 949 B1.

[0015] Such edge reinforcements are also called sub-spacers.

[0016] Such an edge reinforcement arrangement can include one or more layers, wherein a conventional structure includes two layers which are arranged in the form of a surrounding frame on two opposite sides of the membrane-electrode arrangement.

[0017] However, the manufacture and installation of edge reinforcement facilities are complicated and costly. In addition, additional space is required for the overlap between the edge reinforcement facilities and the membrane-electrode facilities, thereby reducing the volume power density of the electrochemical device.

[0018] When the seal is directly attached to the gas diffusion layer, the use of edge reinforcements can be dispensed with, since this creates a smooth transition between the seal and the gas diffusion layer.

[0019] The membrane-electrode arrangement compressed between two seal-gas diffusion layer units is not subjected to excessive clamping peaks.

[0020] Compared to sealing solutions with edge reinforcements, a cell structure with a seal-gas diffusion layer unit can be designed very compactly, since no additional space has to be provided for the overlap between the edge reinforcement and the membrane-electrode arrangement.

[0021] The connection of the seal on the gas diffusion layer can be realized, for example, in an injection molding process. Here, the gas diffusion layer is placed in an injection molding workpiece (preferably divided into multiple parts) and the sealing material is wrapped around its periphery.

[0022] Here, a permeation region is formed at a transition portion between the gas diffusion layer and the sealing material, in which region the sealing material permeates a part of the porous gas diffusion layer.

[0023] This permeable region creates a material-locking and / or form-locking connection between gas diffusion layer and seal, so that gas diffusion layer and seal are mechanically sufficiently well connected to one another during subsequent assembly steps and during operation of the electrochemical device.

[0024] In the permeable region, the pores of the gas diffusion layer are filled with sealing material, so that the transport of cathode fluid or anode fluid to the active region of the electrochemically active unit in this region is made more difficult. Therefore, the permeable region should include as little part of the gas diffusion layer as possible, but should also be large enough to ensure a stable mechanical connection between the gas diffusion layer and the seal.

[0025] In order to limit the permeation area on the gas diffusion layer side, the gas diffusion layer, which can be mechanically compressed in its thickness direction (parallel to the stacking direction of the electrochemical device), is locally compressed by the molding edge in the injection molding tool. As a result, the capillary pressure in the pores of the gas diffusion layer is locally increased and the penetration of the sealing material into the gas diffusion layer is limited in the x-direction and y-direction perpendicular to the thickness direction (z-direction).

[0026] The embossing edge must press the gas diffusion layer with a minimum pressure, thereby limiting the penetration of the sealing material into the gas diffusion layer. However, the embossing edge must not excessively press the gas diffusion layer locally, since in the case of excessive pressing the gas diffusion layer could be damaged, for example due to fiber breakage.

[0027] The extent to which the gas diffusion layer is penetrated by the sealing material depends on the pressure of the sealing material in the injection molding tool, which is locally applied in the individual regions of the gas diffusion layer. The extent to which the gas diffusion layer is penetrated by the sealing material also depends on the viscosity of the sealing material, the temperature of the injection molding tool (which also influences the viscosity of the sealing material) and the properties of the molded edge regions of the gas diffusion layer and other regions of the gas diffusion layer, in particular on the porosity, the tortuosity (i.e. the tortuosity of the transport paths in the gas diffusion layer), the capillary pressure and the hydrophobicity.

[0028] When the seal is attached to the gas diffusion layer during injection molding or similar processes, the sealing material is introduced into the cavity of the injection molding tool at one or several injection points and then spreads along the flow path forming a flow front in the cavity.

[0029] During injection, a pressure gradient is created along the flow path. The highest pressure in the cavity is expected to occur at the injection point. The pressure decreases as the distance from the injection point increases.

[0030] Because in the seal connected to the gas diffusion layer, the seal itself has a relatively small sealing cross section (for example, 5 mm 2 Up to 30mm 2 The gas diffusion layer extends around the gas diffusion layer (in the range of 100 to 200 mm) and the gas diffusion layer can have a relatively large side length (e.g., a side length in the range of 70 mm to 400 mm), and a plurality of flow paths are formed depending on the positioning and number of the injection points, which leads to a large pressure drop over the length of the flow paths during the injection process. The tool internal pressure that occurs in the permeation region of the gas diffusion layer depends on the positioning relative to the injection points. In the section of the permeation region close to the injection point, a higher tool internal pressure is expected to occur during the injection process than in the section farther away from the injection point.

[0031] In the case of known seals injected onto the gas diffusion layer, excessive penetration of the gas diffusion layer by the sealing material may occur in sections close to the injection site of the permeation region, resulting in a local drastic reduction in the porosity of the gas diffusion layer and impairing the function of the electrochemical device.

[0032] In order to reduce the penetration of the sealing material into the gas diffusion layer, it may be necessary to provide a greater number of injection points in the tool and / or to select process parameters in a range that is not conducive to a fast injection molding process (e.g., by using lower tool temperatures, lower injection speeds and / or lower tool internal pressures). All these measures lead to increased tool and / or process costs. Summary of the invention

[0033] The basic object of the present invention is to create an electrochemically active cell for an electrochemical device of the type mentioned at the outset, in which during the production of the electrochemically active cell, a most uniform structure of the permeation region can be achieved along the periphery of the gas diffusion layer, in which permeation region the gas diffusion layer of the electrochemically active cell is penetrated by the sealing material of the seal.

[0034] This object is achieved according to the invention in an electrochemically active cell having the features of the preamble of claim 1 in that the seal comprises a connection region, a distribution region and a connecting region which connects the connection region and the distribution region to one another, wherein the connecting region has a minimum height h C , which is greater than the maximum height H of the allocated area V is smaller than one quarter and smaller than the maximum height H of the connection area A A quarter is smaller.

[0035] The basic idea of ​​the invention is to design the connecting region between the distribution region and the connection region as a constriction which has a high flow resistance, in particular when the seal is produced by injection molding.

[0036] This allows only a small part of the total flow resistance between the injection point and the connecting region of the seal adjoining the gas diffusion layer to be distributed to the distribution region of the seal. Thus, at the beginning of the injection molding process, the distribution region is preferably filled before the connecting region adjoining the gas diffusion layer.

[0037] This also results in the lowest possible internal pressure of the injected sealing material, in particular elastomeric material, occurring in the cavity of the injection-molding tool in the region of the seal directly adjoining the porous gas diffusion layer.

[0038] The structure of the seal corresponds to the flow path of the sealing material injected into the injection molding tool and is preferably designed so that the total flow resistance is within the smallest possible value range, so that the pressure loss between the injection point and different points in the connection area of ​​the seal adjacent to the gas diffusion layer is within the smallest possible value range.

[0039] The distribution area of ​​the seal has a large flow cross section, so that the distribution area can be used as a subdistribution section in the tool cavity during the injection molding process.

[0040] The section of the distribution area with high flow resistance can remain on the finished seal or can be removed by remachining.

[0041] If these sections remain on the seal, they can include a number of functional elements of the seal, such as one or more sealing lips and / or one or more deformation limiters of the seal.

[0042] When producing the seal according to the invention, the flow resistance between the injection point of the seal material and the different sections of the connection region of the seal to the gas diffusion layer lies within a narrow value range, thereby achieving uniform and / or simultaneous shape filling of the connection region during the injection molding process.

[0043] The parameters of the production process can therefore be selected such that the internal pressure in the cavity in the connection region of the seal is significantly lower. The molded edges, which are intended to prevent excessive penetration of the sealing material into the gas diffusion layer, can thus be implemented in such a way that the gas diffusion layer is less stressed. This allows the injection molding process to be carried out smoothly even if the thickness of the gas diffusion layer and the dimensions of the injection molding tool vary within a wide tolerance range.

[0044] Furthermore, process safety is increased by preventing mechanical damage to the gas diffusion layer due to excessive compression.

[0045] When the seal connected to the gas diffusion layer is produced in an injection molding tool, the sealing material shrinks due to the curing process and also undergoes thermal expansion, which may differ from the thermal expansion of the gas diffusion layer. This may lead to stresses in the component and thus to distortions.

[0046] The narrow connecting region between the distribution region and the connecting region of the seal is preferably flexibly deformable, thereby compensating for distortions and / or shrinkages of a portion of the sealing material and thereby preventing distortions of the component.

[0047] The electrochemically active unit according to the invention is used in particular in fuel cell arrangements, in particular in PEM (polymer electrolyte membrane) fuel cell arrangements or in electrolyzers.

[0048] The seal can be connected to only one gas diffusion layer of the electrochemically active cell or to both gas diffusion layers of the electrochemically active cell, in particular to the cathode-side gas diffusion layer and the anode-side gas diffusion layer of the electrochemically active cell.

[0049] Furthermore, the seal can also be connected to the membrane-electrode arrangement and / or the bipolar plates of the electrochemically active cell.

[0050] The seal of the electrochemically active cell according to the invention is preferably produced by injection molding using an injection molding tool.

[0051] Here, the gas diffusion layer having a porous structure is partially penetrated by the sealing material.

[0052] Furthermore, the seal can also be connected to an end plate of an electrochemical device, in particular a fuel cell stack or an electrolyser.

[0053] The seal essentially surrounds the outer edge of the gas diffusion layer to which the seal adjoins.

[0054] The docking area is in direct contact with the gas diffusion layer.

[0055] The distribution area of ​​the seal is arranged outside the docking area and can surround the docking area completely or only in sections.

[0056] The distribution area and the docking area are connected to each other via the connection area.

[0057] The distribution region preferably has a large flow-through cross section perpendicular to the longitudinal direction of the distribution region.

[0058] The cross section of the distribution area is preferably at least 1 mm 2 .

[0059] Furthermore, it can be provided that the cross section of the distribution area is a maximum of 20 mm 2 .

[0060] Maximum height H of the distribution area V Preferably at least 0.5 mm.

[0061] Maximum height H of the distribution area V Preferably a maximum of 2 mm.

[0062] The connecting region has a significantly smaller thickness or height than the dispensing region.

[0063] In the present description and the appended claims, the height of a region of a seal denotes the extension of the relevant region of the seal parallel to the stacking direction of the electrochemical device in which the electrochemically active unit is used.

[0064] The connecting region can be embodied as a film.

[0065] Minimum height h of the connection area C Preferably greater than the maximum height H of the distribution area V 6, in particular 8, and / or preferably smaller than the maximum height H of the docking area. A One sixth, preferably one eighth smaller.

[0066] Minimum height h of the connection area C Preferably it is less than 0.3 mm, particularly preferably less than 0.1 mm, particularly preferably less than 0.05 mm.

[0067] The thickness of the connecting region can vary along the circumference of the gas diffusion layer.

[0068] The electrochemically active cell according to the invention comprises a seal which is preferably directly connected to one or more porous layers of the electrochemically active cell during the injection molding process, wherein a film gate which is integrated into the seal is preferably provided. The film gate can be used to significantly reduce the maximum internal pressure occurring in the cavity of the injection molding tool directly on the porous layer, thereby significantly reducing the penetration of the porous layer by the sealing material.

[0069] In a preferred embodiment of the present invention, it is provided that the minimum height h of the connection area C Less than 0.3 mm, in particular less than 0.1 mm, particularly preferably less than 0.05 mm.

[0070] The connection region can have, for example, a constant height of, for example, 0.1 mm.

[0071] The connecting region is preferably designed at least in sections, in particular substantially completely, as a flexible film.

[0072] The connecting region can have a number of thickened sections in which the connecting region has a minimum height h greater than the connecting region. C Height H D , and these sections are spaced apart from each other in the longitudinal direction of the connecting area.

[0073] In particular, it can be provided here that at least one thickened section extends over the entire width of the connecting region in a transverse direction of the connecting region perpendicularly to the longitudinal direction of the connecting region.

[0074] Furthermore, it can be provided that the height H of the thickened section D , the extension L of each thickened section along the longitudinal direction of the connection area D and / or the distance A between every two thickened sections that follow one another in the longitudinal direction of the connection region. D All change along the longitudinal direction of the connection area.

[0075] The seal can have one sealing lip or a plurality of sealing lips, for example two sealing lips, which form a component of the distribution area or a component of the connection area.

[0076] Furthermore, the seal can have at least one deformation limiter which forms a component of the distribution area or a component of the connection area.

[0077] Such deformation limiters (also referred to as “hard stops”) serve to limit the compression of other elements of the seal, such as the sealing lip, when a clamping force is applied to the electrochemically active cell.

[0078] The deformation limiter can serve in particular as a stop which prevents the sealing element from further deformation when a clamping force is applied.

[0079] In a preferred embodiment of the invention, it is provided that the maximum height H of the distribution area V At least 1.2mm.

[0080] A cross section of the dispensing region perpendicular to the longitudinal direction of the dispensing region may remain substantially constant along the longitudinal direction of the dispensing region or may vary along the longitudinal direction of the dispensing region.

[0081] In particular, it can be provided that the size of the cross section of the distribution area changes depending on the distance from the injection point of the sealing material. For example, it can be provided that the size of the cross section of the distribution area increases as the distance from the injection point increases.

[0082] In a preferred embodiment of the invention, it is provided that the seal is injection-molded and that the material of the seal penetrates a part of at least one gas diffusion layer of the electrochemically active cell.

[0083] The electrochemically active cell according to the invention can comprise two seals which are each connected to at least one gas diffusion layer.

[0084] The electrochemically active unit according to the invention is suitable in particular for use in electrochemical devices, for example in fuel cell stacks or electrolyzers.

[0085] When the electrochemical device is in the assembled state, the seal of the electrochemically active cell can bear in a fluid-tight manner against another seal and / or against the bipolar plate.

[0086] The basic design and production of such an electrochemical device is described in patent DE 10 2015 109 393 A1, to which reference is hereby made and which is made part of the present application.

[0087] The material of the seal is preferably an elastomeric material.

[0088] Further features and advantages of the present invention are the subject of the following description and the accompanying drawings of exemplary embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] The figure shows:

[0090] Figure 1 A schematic top view of an electrochemically active cell of an electrochemical device is shown, the electrochemical device comprising a membrane-electrode arrangement (not shown), at least one gas diffusion layer and a seal connected to at least one of the at least one gas diffusion layers;

[0091] Figure 2 Shown along Figure 1 The line 2-2 shown passes through Figure 1A partial cross-sectional view of a seal and a gas diffusion layer is shown, wherein, as can be seen from the cross section, the seal comprises a docking region, a distribution region and a connecting region connecting the distribution region and the docking region to one another, the docking region penetrating a portion of at least one gas diffusion layer of the electrochemically active cell, the distribution region comprising one or more sealing lips and / or deformation limiters of the seal;

[0092] Figure 3 A second embodiment of the electrochemically active cell of the electrochemical device is shown corresponding to Figure 1 A top view of a sealing member, wherein the connecting region of the seal has thickened sections which are spaced apart from one another in the longitudinal direction of the connecting region; and

[0093] Figure 4 Shown along Figure 3 The line 4-4 shown passes through Figure 3 The at least one gas diffusion layer and the seal of the electrochemically active unit shown in FIG. Figure 2 A partial cross-section of the seal, wherein it can be seen from the cross-section that the seal includes a connecting area, a distribution area and a connecting area connecting the connecting area and the distribution area to each other, wherein the connecting area has thickened sections spaced apart from each other in the longitudinal direction of the connecting area.

[0094] Identical or functionally equivalent elements are provided with the same reference symbols in all figures. DETAILED DESCRIPTION

[0095] exist Figure 1 and 2 The electrochemically active unit shown in the figure and indicated as a whole by 100 for an electrochemical device (not shown as a whole), such as a fuel cell stack or an electrolyzer, comprises a membrane-electrode arrangement (not shown), at least one gas diffusion layer 102 and a seal 104, which extends around the gas diffusion layer 102 along a longitudinal direction 106 of the seal 104.

[0096] As can be Figure 2 As can be best seen in the cross-sectional view of , the seal 104 comprises a connection region 108 , a distribution region 110 facing away from the gas diffusion layer 102 , and a connecting region 112 which connects the connection region 108 and the distribution region 110 to one another.

[0097] The seal 104 is preferably designed in one piece.

[0098] The seal 104 is preferably injection molded.

[0099] The seal 104 is preferably formed from an elastomeric material.

[0100] The elastomeric material preferably penetrates into the associated gas diffusion layer 102 , so that the seal 104 is connected to the gas diffusion layer 102 in a materially and / or form-fitting manner.

[0101] The outer edge region of the gas diffusion layer 102 which is penetrated by the material of the seal 104 and thus forms part of the connection region 108 is located at Figure 2 The region 114 is indicated by shading and is referred to as the infiltration region 114 .

[0102] The connection region 108 extends in the longitudinal direction 116 , preferably in a closed annular manner around the gas diffusion layer 102 .

[0103] The longitudinal direction 116 of the connecting region 108 extends generally parallel to the longitudinal direction 106 of the sealing element 104 .

[0104] The maximum height H of the docking area 108 A Preferably, it corresponds at least to the height H of the gas diffusion layer 102 G .

[0105] In the present description and the appended claims, the height of a component refers to the extension of the respective component in a stacking direction 118 of an electrochemical device in which a plurality of electrochemically active cells 100 are arranged one above the other along the stacking direction.

[0106] The electrochemically active cells 100 can form, together with a bipolar plate (not shown) in each case, an electrochemical cell of an electrochemical device.

[0107] The electrochemical device then comprises a plurality of electrochemical cells arranged one above the other in a stacking direction 118 and preferably two end plates, between which the stack of electrochemical cells is arranged and which are clamped relative to one another by means of a clamping device (not shown here), thereby applying a clamping force directed along the stacking direction 118 to the electrochemical cells arranged therebetween and in particular their electrochemically active units 100.

[0108] The connecting region 112 of the seal 104 follows the connecting region 108 outwardly in a transverse direction 120 perpendicular to the longitudinal direction 106 of the seal 104 and perpendicular to the stacking direction 118 .

[0109] The connecting region 112 is preferably designed as a flexible film and has a minimum height h C , which is higher than the maximum height H of the docking area 108 A A quarter is smaller.

[0110] The connecting region 112 is preferably designed essentially to be elastically deformable.

[0111] The connecting region 112 extends in the circumferential direction around the connecting region 108 along a longitudinal direction 122 of the connecting region 112 and is preferably designed to be annularly closed.

[0112] The longitudinal direction 122 of the connecting region 112 is generally parallel to the longitudinal direction 106 of the seal 104 .

[0113] Adjoining the connecting region 112 outwardly in the transverse direction 120 is the distribution region 110 , which has one or more sealing lips 124 .

[0114] When the seal 104 is in an idle state, ie in a relaxed state in which no sealing force is applied, the sealing lip 124 has a height H corresponding to the maximum height of the dispensing area 110. V .

[0115] If there are a plurality of sealing lips 124, the heights of the sealing lips 124 in the relaxed state may also differ from one another, wherein the maximum height H of the sealing lips 124 is V Therefore, the maximum height H of the distribution area 110 is formed V .

[0116] The sealing lip 124 extends in the longitudinal direction 126 of the dispensing region 110 in the circumferential direction around the connecting region 112 and around the connection region 108 and is preferably designed to be annularly closed.

[0117] The longitudinal direction 126 of the dispensing area 110 extends generally parallel to the longitudinal direction 106 of the sealing element 104 .

[0118] If a plurality of sealing lips 124 are present in the distribution area 110, these are separated from one another by a respective lower middle area 128, which has a minimum height h Z .

[0119] In order to limit the maximum deformation of the sealing lip 124 , the dispensing region 110 can furthermore comprise a deformation limiter 130 .

[0120] The deformation limiter 130 is preferably arranged outside the sealing lip 124, preferably outside the annularly closed sealing lip, and has a height H S .

[0121] The deformation limiter 130 preferably has a flat tip with a substantially flat stop surface 132 .

[0122] The deformation limiter 130 can extend in the longitudinal direction 126 of the dispensing area 110 in the circumferential direction around the sealing lip 124 and is preferably designed to be annularly closed.

[0123] The deformation limiter 130 is preferably separated from the single sealing lip 124 or from the outermost sealing lip 124 by a central region 134 which has a smaller height than the sealing lip 124 and the deformation limiter 130 .

[0124] The intermediate region 134 has a minimum height h that can be aligned with the intermediate region 128 between the two sealing lips 124. Z The same minimum height h′ Z .

[0125] However, the minimum height h′ of the middle region 134 Z It can also be greater or less than the minimum height h of the middle area 128 Z .

[0126] The minimum height h of the connection area 112 C The maximum height H of the distribution area 110 V The connection area 112 is formed at a constriction between the dispensing area 110 and the connecting area 108 of the seal 104 .

[0127] For example, the above-mentioned seal 104 on the gas diffusion layer 102 is produced by injection molding as follows:

[0128] The first injection molding tool part (not shown) is placed with the molded edge onto the gas diffusion layer 102, for example Figure 2 The second injection molding tool part (not shown) is in contact with the boundary surface 136 of the gas diffusion layer 102, which is shown at the top in the middle, and the second injection molding tool part (not shown) is in contact with the boundary surface 136 of the gas diffusion layer 102, which is shown at the top in the middle. Figure 2 On the boundary surface 138 shown in the lower middle, in order to serve as a counter-seat for pressing the gas diffusion layer 102 in the region of the molded edge of the first injection molding tool part, so that a cavity to be filled with a preferably elastomeric injection molding material or sealing material is formed between the two injection molding tool parts.

[0129] The injection point for metering the injection molding material into the cavity is preferably arranged outside the deformation limiter 130 on a lug designed specifically for this purpose.

[0130] When the cavity is subsequently filled with the injection molding material to be cured, which forms the seal 104, the injection molding material first penetrates into the distribution area 110 on the outer edge of the seal 104, which has a large flow-through cross section viewed in a direction perpendicular to the longitudinal direction 126, for example 1 mm 2 To about 20mm 2 .

[0131] The heights h of the different regions of the distribution area 110 Z , h′ Z , HS and H V Preferably it is in the range of about 0.5 mm to 2 mm.

[0132] Conversely, the height h of the connection region 112 C Significantly smaller and preferably less than 0.3 mm, in particular less than 0.1 mm, particularly preferably less than 0.05 mm.

[0133] The height h of the connection area 112 C There may be a change in the longitudinal direction 122 of the connection region 112 and thus a change along the circumference of the gas diffusion layer 120 .

[0134] Due to its small height, the connecting region 112 has a significantly higher flow resistance to the injected injection molding material than the distribution region 110 , so that the injected injection molding material is first distributed in the distribution region 110 and only then enters the connection region 108 through the connecting region 112 .

[0135] The injection molding material also penetrates from the cavity into the edge region of the porous gas diffusion layer 102 facing the cavity, so that the permeation region 114 of the gas diffusion layer 102 is penetrated by the material of the seal 104, thereby connecting the connection region 108 of the seal 104 to the gas diffusion layer 102 in a material-locking and / or form-locking manner.

[0136] In this case, the seal 104 substantially completely surrounds the outer surface 140 of the gas diffusion layer 102 .

[0137] After the injection molding material has hardened to form an elastomeric sealing material and the injection molding tool parts have been removed, the assembly consisting of the seal 104 and the gas diffusion layer 102 has a Figure 2 The configuration shown in .

[0138] The gas diffusion layer 102 with the seal 104 injected thereon can now be joined with a membrane-electrode arrangement and preferably a further gas diffusion layer (which can also have a seal injected thereon) to form an electrochemically active unit 100 .

[0139] An electrochemical device can be formed from electrochemically active cells 100 arranged one behind the other in stacking direction 118 , pole plates arranged between them, and end plates arranged at the ends.

[0140] Figure 3 and 4 The second embodiment of the electrochemically active cell 100 shown in Figure 1 and 2The difference from the first embodiment shown in FIG. 1 is that the connection region 122 of the seal 104 has a plurality of thickened sections 142 , which have a height h greater than the section of the connection region 112 located between them. C Height H D .

[0141] For example, it can be designed that the height H D At least equal to height h C Three times.

[0142] In particular, it can be set that the height H D At least approximately equal to 0.15 mm, preferably at least approximately 0.3 mm, particularly preferably at least approximately 0.9 mm.

[0143] In the longitudinal direction 122 of the connecting region 112 , the thickened sections 142 are spaced apart from one another.

[0144] In particular, the distance A between two thickened sections 142 that follow one another in the longitudinal direction 122 of the connecting region 112 is D It may be at least equal to 5 mm, in particular at least equal to 10 mm.

[0145] The extension L of each thickened section 142 along the longitudinal direction 122 of the connecting region 112 D Preferably, the distance A between two consecutive thickened sections 142 along the longitudinal direction 122 of the connecting region 112 is less than D .

[0146] Since the thickened section 142 is thicker, it serves to mechanically stabilize the connecting region 112 , in particular after the seal 104 has been removed from the injection-molding tool part.

[0147] also, Figure 3 and 4 The second embodiment of the electrochemically active cell 100 shown in FIG. 1 is similar in design, function and method of production to that in FIG. Figure 1 and 2 The present invention is consistent with the first embodiment shown in , and reference can be made to the above description for these contents.

Claims

1. An electrochemically active unit for an electrochemical device, comprising a membrane-electrode arrangement, at least one gas diffusion layer (102) and a seal (104) connected to at least one of the at least one gas diffusion layers (102), in, The seal (104) comprises a connection area (108), a distribution area (110) and a connection area (112) connecting the connection area (108) and the distribution area (110) to each other. The connection area (112) has a maximum height (H) greater than that of the distribution area (110). V ) is smaller than one quarter of the maximum height (H A ) is smaller than one quarter of the minimum height (h C ), The connecting region (112) has a thickened section (142), in which the connecting region (112) has a minimum height (h C ) Greater height (H D ), and the thickened sections are spaced apart from each other in the longitudinal direction (122) of the connecting region (112), The distance (A) between two thickened sections (142) that follow one another in the longitudinal direction (122) of the connecting region (112) is D ) change along the longitudinal direction (122) of the connection area (112), and, Wherein, the height (H) of the thickened section (142) D ) is less than the maximum height (H) of the docking area (108) A ).

2. The electrochemically active unit according to claim 1, It is characterized in that The minimum height (h) of the connection area (112) C ) is less than 0.3mm.

3. The electrochemically active unit according to claim 1 , It is characterized in that The connecting region (112) is designed at least in sections as a flexible film.

4. The electrochemically active unit according to claim 1, It is characterized in that At least one of the thickened sections (142) extends over the entire width of the connecting region (112) in a transverse direction (120) of the connecting region (112) that runs perpendicularly to a longitudinal direction (122) of the connecting region (112).

5. The electrochemically active unit according to claim 1, It is characterized in that The height (H) of the thickened section (142) D ) and / or the extension (L) of each thickened section (142) along the longitudinal direction (122) of the connecting region (112) D ) changes.

6. The electrochemically active unit according to claim 1, It is characterized in that The seal (104) has at least one sealing lip (124), which forms a component of the distribution area (110) or a component of the connection area (108).

7. The electrochemically active unit according to claim 1, It is characterized in that The seal (104) has at least one deformation limiter (130), which forms a component of the distribution area (110) or a component of the connection area (108).

8. The electrochemically active unit according to claim 1, It is characterized in that The maximum height (H) of the distribution area (110) V ) is at least 1.2 mm.

9. The electrochemically active unit according to claim 1, It is characterized in that The cross section of the dispensing area (110) varies along a longitudinal direction (126) of the dispensing area (110).

10. The electrochemically active unit according to claim 1, It is characterized in that The seal (104) is injection molded and the material of the seal (104) penetrates a portion of at least one gas diffusion layer (102) of the electrochemically active cell (100).

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