Fuel cell device and single cell for fuel cell stack

Abstract

The present invention relates to a fuel cell device (1), which: has a membrane electrode assembly (2) including a cathode, an anode, and a membrane disposed between the cathode and the anode; has an active area (3) substantially predefined by the membrane electrode assembly (2); and has a sealing structure (4) laterally assigned to the membrane electrode assembly (2). The sealing structure (4) includes a sealing flange (6) extending into or passing through an edge area (5) outside the active area (3) for axially and gastight covering of a medium channel (8) constructed in an adjacent bipolar plate (7) and located within the edge area (5). The present invention also relates to a single cell for a fuel cell stack having such a fuel cell device.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a fuel cell device and a single cell having such a fuel cell device for a fuel cell stack. BACKGROUND OF THE INVENTION

[0002] Fuel cell devices in particular include a membrane electrode assembly, which includes a cathode, an anode, and a membrane disposed between the cathode and the anode. By the membrane electrode assembly or by the dimensions of the membrane electrode assembly, an active area is substantially predefined, in which the electrochemical reaction of the fuel cell takes place. Here, the membrane electrode assembly is laterally assigned a sealing structure, which in particular ensures that the reaction media can only flow to where they are required for the electrochemical reaction.

[0003] A fuel cell device according to the preamble of claim 1 is shown in DE 19703214 C 1. In this case, the sealing device is mounted or impregnated into the edges of the cathode and anode of the membrane electrode assembly. In order to supply media to the anode or cathode, vertical, i.e., extending in the stack direction, supply devices are incorporated into the membrane electrode assembly, which has laterally configured holes facing the cathode or the anode. This design is disadvantageous because the active area predefined by the membrane electrode assembly is reduced due to the insulating sleeves extending vertically through the membrane electrode assembly.

[0004] In DE 102010024316 A1, which describes the features of the preamble of claim 1, a sealing device for a bipolar plate for a fuel cell is described, in which a media inlet and a media outlet are configured. The sealing device can be elastically deformed in part, whereby the sealing device can be prefabricated as a separate component and the bipolar plate can be inserted into the sealing device by temporarily stretching the sealing device. Instead of stretching, the sealing device can also be molded onto it.

[0005] In JP2007287364 A, a single cell having a fuel cell device is also described, which includes a sealing structure for sealing as protection against undesired outflow of reaction media. In US2007 / 196716A1, a fuel cell device and a single cell having such a fuel cell device including a bipolar plate 25 are also described, which single cell has a sealing structure 23.

[0006] US2011 / 318666 A1 describes a fuel cell stack, in which media connection ends are provided in regions (protrusions 214, 216, 218, 226) that protrude beyond the rectangular basic shape of the stack. It can be seen from JP S62211868A1 that there are sealing structures with flanks that protrude beyond the dimensions of the substrate.

[0007] JP 2008140740 A describes a fuel cell stack in which a sealing structure is used to distribute the working medium. Summary of the Invention

[0008] Accordingly, the object of the present invention is to provide a fuel cell device in which the active area remains constant or is maximized. The object of the present invention is also to provide a corresponding single cell for a fuel cell stack that can be manufactured particularly advantageously.

[0009] The object regarding the fuel cell device is solved by a fuel cell device having the following features. According to one aspect of the present invention, the fuel cell device has: a membrane electrode assembly, the membrane electrode assembly including a cathode, an anode, and a membrane disposed between the cathode and the anode; an active area substantially predefined by the membrane electrode assembly, in which the electrochemical reaction of the fuel cell takes place; and a sealing structure laterally assigned to the membrane electrode assembly, the sealing structure being configured such that the reaction media only flow to the places where they are needed for the electrochemical reaction, wherein there is a marginal area predefined by the dimensions of the adjacent bipolar plates, the marginal area circumferentially limiting the active area, characterized in that the sealing structure includes a sealing flange extending into the marginal area outside the active area or extending through the marginal area for axially and gastight covering of a media channel constructed in the adjacent bipolar plate and located within the marginal area and extending up to the edge of the bipolar plate, the media channel being configured to laterally transfer media into or out of the active area. Here, the sealing structure particularly includes a sealing flange extending into or through the marginal area. The marginal area is arranged outside the active area. The active area is circumferentially limited by an inactive marginal area, wherein the marginal area is predefined by the dimensions of the adjacent bipolar plates. The sealing flange extending into or through the marginal area is designed to axially and gastight cover the media channel constructed in the adjacent bipolar plate, located within the marginal area, and extending up to the edge of the bipolar plate. The marginal area and the sealing flange can be reduced to a minimum size such that a lateral, and thus perpendicular to the stacking direction, conveyance of media, such as reaction media or cooling media, is possible.

[0010] It has proven to be advantageous for the sealing structure, in particular its sealing flange, to be formed in a dimensionally stable manner with respect to the compressive and / or tensile stresses acting axially thereon. This ensures that the fuel cell device can be placed flat and dimensionally stable on the bipolar plate. If only the sealing flange is implemented in a dimensionally stable manner, flat covering of one or more media channels constructed in adjacent bipolar plates can be achieved in the edge region. Preferably, the sealing structure is composed of a plastic or a plastic mixture. In order to maintain its dimensional stability even during the hot pressing process, it is advantageous for the plastic or the plastic mixture to have a high thermal (dimensional) stability.

[0011] In order to ensure the sealing function of the sealing flange, it can be reasonable for the sealing flange to extend beyond the edge region.

[0012] In order to additionally seal the cathode of the membrane electrode assembly relative to the anode, it is advantageous for the sealing structure to have a sealing edge that seals the membrane electrode assembly laterally.

[0013] The task regarding the unit cell for a fuel cell stack is solved by a unit cell having the following features.

[0014] The unit cell in particular includes the fuel cell device of the present invention as described above and a first bipolar plate arranged adjacent to the membrane electrode assembly. The first bipolar plate is also divided into an edge region and an active region, wherein the first bipolar plate includes in the edge region a media channel that is axially hermetically covered by the sealing flange of the fuel cell device and extends up to the edge of the bipolar plate. The media channel is designed to transfer media into the active region or transfer media out of the active region.

[0015] Here, the following advantage has also emerged: the bipolar plate can be minimized in terms of area. Here, the active region remains unchanged, while the edge region outside the active region can be reduced to a minimum area. Subsequently, the relevant media are conveyed by a separate device, such that the bipolar plate is constructed without a media conveying device constructed in the stacking direction. Here, the media are conveyed into the active region laterally or on the side, that is, thus perpendicular to the stacking direction of the fuel cell stack.

[0016] In order to further increase the active area, it is reasonable that the first bipolar plate includes a first medium inlet channel and a first medium outlet channel in the edge area. In the bipolar plate, a first flow field is constructed in the active area, and the first flow field is fluidly connected to the first medium inlet channel and the first medium outlet channel. The sealing structure further includes a sealing flange extending into or through the edge area for axially and airtightly covering the first medium inlet channel, and the sealing flange is formed as a first inlet sealing flange. A sealing flange extending into or through the edge area is also provided for axially and airtightly covering the first medium outlet channel, and the sealing flange is formed as a first outlet sealing flange.

[0017] One or more first medium inlet channels and one or more medium outlet channels can be constructed on the same side of the bipolar plate or can be constructed on different sides of the bipolar plate. In a preferred embodiment, at least one first medium inlet channel is constructed on the first side of the bipolar plate and at least one first medium outlet channel is arranged on the side of the bipolar plate opposite to the first side. In the case where the medium inlet channel and the medium outlet channel are arranged opposite to each other, it may also be reasonable that the medium inlet channel on one side is laterally offset with respect to the first medium outlet channel on the other opposite side.

[0018] An advantageous design of the fuel cell stack provides a second bipolar plate, which includes a second medium inlet channel and a second medium outlet channel. The second bipolar plate also has a second flow field, and the second flow field is fluidly connected to the second medium inlet channel and the second medium outlet channel. The sealing structure further includes: a second inlet sealing flange extending into or through the edge area for axially and airtightly covering the second medium inlet channel; and a second outlet sealing flange extending into or through the edge area for axially and airtightly covering the second medium outlet channel. In the case of the second bipolar plate, these medium channels can also be arranged on the same side or can be arranged on different sides.

[0019] Associated with this design is the following advantage: Now two different media can enter the active area via the edge area. Preferably, these are the two reaction media of the fuel cell system; however, it is also possible to use a cooling medium. In addition, with this design, the active area can always be maximized, and in the case of corresponding shaping of the sealing flanges, the edge area can be minimized.

[0020] In order to enable the first bipolar plate and the second bipolar plate to be connected to each other safely and hermetically, it has proven reasonable to provide a composite layer with a void between the first bipolar plate and the second bipolar plate. The composite layer is designed to hermetically seal the active area laterally. In the area of the void, one or more media channels are unobstructed. Thus, it is ensured that no media channels, such as media inlet channels or media outlet channels, are sealed or blocked by the composite layer. Here, the composite layer should be understood as a bonding layer, which is constructed of a bonding material for bonding the first bipolar plate and the second bipolar plate. The composite layer can be coated onto the bipolar plate in a U-shape, whereby the composite layer leaves the active area unobstructed.

[0021] For additional sealing and for enabling the bipolar plate to be connected to the fuel cell device safely, it has proven advantageous that the composite layer consists of multiple parts; and that a first inlet sealing flange and a first outlet sealing flange project beyond the void of the composite layer for constructing projections. By means of the projections, it is ensured that even when pressure or tensile force is applied to the fuel cell stack in the stacking direction, the sealing flanges are not displaced, compressed or stretched so far that their sealing function may be lost.

[0022] Additionally, if a connecting layer that forms an overlapping portion with the composite layer is coated onto the first inlet sealing flange and onto the first outlet sealing flange, the sealing can be improved. The connecting layer can also be understood as a bonding layer, which on the one hand bonds to the composite layer and on the other hand bonds the first bipolar plate and the second bipolar plate in the area of these media channels. Description of the Drawings

[0023] In the following, the present invention is further explained with reference to the embodiments shown in the drawings; wherein:

[0024] Figure 1 The fuel cell device is shown in a top view;

[0025] Figure 2 The (first) bipolar plate is shown in a top view;

[0026] Figure 3 Shown is Figure 2 section III-III in;

[0027] Figure 4 Shown in a top view is Figure 2 the (first) bipolar plate with the coated composite layer in;

[0028] Figure 5 Shown is Figure 4 section V-V in;

[0029] Figure 6shows a single cell, which includes Figure 4 the (first) bipolar plate in Figure 1 with the fuel cell device in

[0030] Figure 7 shows Figure 6 the cross-section VII-VII in

[0031] Figure 8 shows Figure 6 the single cell with a coated connection layer of

[0032] Figure 9 shows Figure 8 the cross-section IX-IX in

[0033] Figure 10 shows a single cell, which corresponds to Figure 8 the single cell in

[0034] Figure 11 shows Figure 10 the cross-section XI-XI in the state where the single cell is not pressed in

[0035] Figure 12 shows Figure 10 the cross-section XII-XII in the state where the single cell is pressed in

[0036] Figure 13 shows the (second) bipolar plate in a bottom view, that is, a view of the surface of the bipolar plate facing the membrane electrode assembly

[0037] Figure 14 shows Figure 13 the cross-section XIV-XIV in

[0038] Figure 15 shows a cross-sectional view corresponding to Figure 14 composed of the first bipolar plate and the second bipolar plate arranged adjacent to the first bipolar plate

[0039] Figure 16 shows a fuel cell stack in a perspective view, which has a plurality of single cells arranged according to Figure 10 ; and

[0040] Figure 17 shows Figure 16 the fuel cell stack in

[0041] It should be pointed out in advance that the dimensions, dimensional ratios, and scales of the illustrated diagrams are not fixed and may vary. Especially in the case of these cross-sectional views, the individual layers are presented in such a way that it is possible to understand in what mutual orientation and in what order these individual layers are stacked on top of each other. Detailed Description

[0042] In Figure 1 a fuel cell device 1 is shown, which fuel cell device includes a membrane electrode assembly 2 arranged in its center, which membrane electrode assembly has a cathode, an anode, and a proton-conducting membrane arranged between the cathode and the anode. By means of this membrane electrode assembly 2, an active area 3 is substantially predefined, which active area is drawn in this figure by an internal dashed line. The active area 3 extends not only in the plane (x-y plane) but also in the stacking direction (z-direction) of the membrane electrode assembly 2, which stacking direction points out of the plane of the paper.

[0043] The active area 3 is the area in which the fuel cell formed by the membrane electrode assembly 2 undergoes an electrochemical reaction. In the case of this electrochemical reaction, a fuel (for example, hydrogen) is guided to the anode, where the fuel is catalytically oxidized to protons while releasing electrons. These protons are transferred through the ion-exchange membrane to the cathode. The electrons drawn from the fuel cell flow through an electrical consumer, preferably to an electric motor for driving a vehicle or to a battery pack. Subsequently, these electrons are guided to the cathode. At the cathode, an oxidizing medium (for example, oxygen or oxygen-containing air) is reduced to anions by absorbing these electrons, and these anions then react with these protons to form water.

[0044] To ensure that the fuel reaches the cathode directly or the oxidizing medium reaches the anode directly, the membrane electrode assembly 2 is laterally provided with a sealing structure 4. The sealing structure 4 includes components that extend into the edge area 5 or project beyond this edge area. Thereby, that is, these components are arranged outside the active area 3. In other words, the edge area 5 limits the active area 3 radially, laterally, or on the axial side.

[0045] It can be seen that the sealing structure 4 includes a sealing flange 6 that extends into the edge area 5 or extends through the edge area 5 for axially and gastight covering of a medium channel 8 that is constructed in an adjacent bipolar plate 7 and is within the edge area 5. In Figure 1 the fuel cell device shown has a total of four sealing flanges 6. Two of these sealing flanges are arranged opposite each other on the shorter side 9a of the fuel cell device 1. The other two sealing flanges 6 are arranged opposite each other and are offset from each other on the longer side 9b of the membrane electrode assembly 1. In the present case, all the sealing flanges 6 have a rectangular shape. However, a polygonal shape of these sealing flanges is possible, and a circular sealing flange 6 is also considered.

[0046] The sealing structure 4 and in particular the sealing flange 6 are formed in a shape-stable manner with respect to the axially acting compressive and / or tensile stresses. It can also be seen that the sealing flange 6 extends beyond the edge region 5. However, it is also possible that one or more of these sealing flanges 6 only extend into the edge region 5, but do not completely cover the edge region or protrude laterally beyond the edge region.

[0047] It can also be seen that the sealing structure 4 has a sealing edge 10 at the side of the membrane electrode assembly 2. The sealing line formed by the sealing edge 10 seals the membrane electrode assembly 2 to prevent the medium from flowing out laterally.

[0048] In Figure 2 a bipolar plate 7 is shown, by means of which a single cell 11 for a fuel cell stack 12 can be formed together with the fuel cell device 1. The first bipolar plate 7a also has an inner active region 3 shown in dashed lines and an outer edge region 5 shown in dashed lines. A plurality of medium channels 8 are provided in the edge region 5, and these medium channels can be divided into a first medium inlet channel 8a shown on the left side of the drawing and a first medium outlet channel 8b shown on the right side of the drawing.

[0049] In the present case, five first medium inlet channels in the first medium inlet channel 8a and five first medium outlet channels in the first medium outlet channel 8b are configured in the first bipolar plate 7a. Other numbers are possible. The first medium inlet channel 8a and the first medium outlet channel 8b are fluidly connected to each other via a first flow field 13a. The flow field 13a is located within the active region 3 and can supply the reaction medium to the adjacent membrane electrode assembly 2. In the example according to Figure 2 the flow field 13a has a plurality of guiding means or walls 14 for uniformly distributing the reaction medium within the surface of the membrane electrode assembly 2. However, it is also possible to use other types of flow fields 13a, such as a flow field in which the flow of the reaction medium is guided in a meandering manner through the region of the active region. In addition, the distance between the walls 14 or the spacers can also be changed. The depth of the channels formed by the adjacent walls 14 can also be implemented and changed to be of different depths.

[0050] As can be seen from Figure 3 , that is, according to Figure 2 in cross-section III-III, a flow field 13c is also configured on the side of the first bipolar plate 7a facing away from the membrane electrode assembly 2, and this flow field is for other media, such as a cooling medium, to flow through.

[0051] As Figure 4As shown, the composite layer 15, in particular the bonding layer, is applied to the first bipolar plate 7a in the edge region 5. The composite layer 15 is composed of multiple parts or has voids 16 in the regions of the medium channels 8a, 8b. The voids 16 ensure that the medium inlet channel 8a and the medium outlet channel 8b are not sealed and allow for subsequent medium guidance.

[0052] The composite layer 15 installed in the edge region 5 extends along the long side 17a of the first bipolar plate 7a such that it forms a flush termination with the edge region 5 pre-defined by the dimensions of the bipolar plate 7. Through this composite layer 15, the active region 3 is sealed against the surrounding environment, and the material of the composite layer 15 should be selected to ensure this sealing function. Plastics or plastic mixtures can be used as the material of the composite layer 15. Preferably, the plastics or plastic mixtures have a lower thermal stability compared to the plastics or plastic mixtures of the sealing structure 4 or the sealing flange 6. Thus, the sealing flange 6 can sink into the composite layer 15 during the hot pressing process and preferably fuse with the composite layer, where the sealing flange 6 maintains its shape stability. In other words, the melting point of the material of the sealing structure 4 is higher than the melting point of the material of the composite layer 15. In Figure 5 、i.e. Figure 4 in the cross-section V-V, it can be seen that the composite layer 15 or the bonding material and the bipolar plate 7 form a flush termination along their long sides 17a. The selected illustration of the composite layer 15 is exemplary. The composite layer can be designed to be much thinner than the first bipolar plate 7a.

[0053] Now, in order to form a single cell 11 for the fuel cell stack 12, the membrane electrode assembly 2 shown in Figure 1 is coated or placed flat on the first bipolar plate 7a covered with the composite layer 15 according to Figure 4 ( Figure 6 ). Here, the sealing flange 6 on the left side of the fuel cell device 1 axially and airtightly covers the medium channel 8 on the left side of the first bipolar plate 7a. The sealing flange 6 on the right side of the fuel cell device 1 axially and airtightly covers the medium channel 8 on the right side of the first bipolar plate 7a. In other words, the sealing flange 6 on the left side is formed as a first inlet sealing flange 6a for axially and airtightly covering the first medium inlet channel 8a on the left side. Correspondingly, the sealing flange 6 on the right side is formed as a first outlet sealing flange 6b for axially and airtightly covering the first medium outlet channel 8b on the right side. The sealing flanges 6 provided on the long side 17a of the bipolar plate 7a are placed flat on the composite layer 15. These sealing flanges can be divided into a second inlet sealing flange 6c and a second outlet sealing flange 6d. Preferably, if an axial pressure is applied to the single cell 11, such as when (hot) pressing the single cell 11, the second sealing flanges 6c, 6d sink into the composite layer 15.

[0054] In the central region, i.e., at the location where the active area 3 is located, the sealing structure 4 of the fuel cell device 1 is adapted to the inner contour pre-given by the composite layer 15 in terms of its outer contour. Here, the portion of the sealing structure 4 without a sealing flange is configured as a contact point, contact line 18 or contact surface with the composite layer, such that the sealing function is additionally ensured.

[0055] In Figure 7 , i.e., Figure 6 Cross-section VII-VII in shows an uncompressed cross-sectional view of the single cell 11. It can be seen that the first sealing flanges 6a, 6b project beyond the composite layer 15 and form a projection 19 with this composite layer. In this case, the necessary lateral sealing is ensured. Here, the illustration selected should not be understood in the correct scale either. The thickness of each layer may change, especially after the connection process or bonding process (hot pressing process), after which these layers may appear to act as if they were a single common layer or like a single common layer. Then, the region of the void 16 between the inlet sealing flange 6a and the channel 8 is also minimized such that the inlet sealing flange 6a axially covers these channels 8. Now, the medium can be conveyed along the stacking direction below the first inlet sealing flange 8a to the membrane electrode assembly 2. Then, the (partially) used medium can leave the single cell 11 of the fuel cell stack 12 along the stacking direction below the first outlet sealing flange 8b.

[0056] In Figure 8 , the connection layer 20 is coated onto the first inlet sealing flange 8a and onto the first outlet sealing flange 8b, and this connection layer should be understood as another bonding layer. The composite layer 15 and the connection layer 20 ensure a reliable connection of the first bipolar plate 7a to the second bipolar plate 7b along the stacking direction. The composite layer 15 and the connection layer 20 form an overlap 21 such that these two layers have a contact surface along the stacking direction. Thereby, the sealing function is ensured. The overlap 21 can be further seen from Figure 9 , i.e., Figure 8 Cross-section IX-IX in. Here, an illustration in the correct scale is not selected either to illustrate the stacking arrangement of the individual layers.

[0057] Now, the second bipolar plate 7b can be coated onto the composite layer 15 and the connection layer 20 connected to this composite layer. This can be seen from Figure 10 . The first bipolar plate 7a and the second bipolar plate 7b can be joined to each other through a bonding layer such that a single cell with at most a tiny projection is formed by the first bipolar plate 7a, the fuel cell device 1, and the second bipolar plate 7b.

[0058] Like the first bipolar plate 7a, in Figure 10 and Figure 13The second bipolar plate 7b shown in the figure also has a flow field 13c on the side facing away from the membrane electrode assembly 2 for guiding the cooling medium. This flow field 13c is substantially within the active area 3. This flow field is fluidly connected to the coolant inlet channel 8e and to the coolant outlet channel 8f.

[0059] However, the second bipolar plate 7b has one or more second medium inlet channels 8c and one or more second medium outlet channels 8d on the side facing the membrane electrode assembly 2 ( Figure 13 ). The second bipolar plate also includes a second flow field 13b that is fluidly connected to the second medium inlet channel 8c and the second medium outlet channel 8d, through which one of the reaction media can be conveyed to the membrane electrode assembly 2.

[0060] In Figure 11 , that is Figure 10 , in cross-section XI-XI, the single cell 11 is shown uncompressed or unjoined, while Figure 12 , that is cross-section XII-XII, shows the configuration after the joining process. In Figure 11 it can only be seen that, in the stacking direction, the second bipolar plate 7a is coated onto the connecting layer 20 and the composite layer 15. In the unjoined illustration, two sealing flanges 6c, 6d can also be seen. They are "lower" relative to the inlet sealing flange 6a (refer to the illustration in Figure 11 ), and thus they also do not have cross-section hatching. After the joining or hot pressing process, the second inlet sealing flange 6c and the second outlet sealing flange 6d can no longer be seen in this illustration. Preferably, they are embedded into the composite layer 15.

[0061] Figure 12 shows that: after the joining or hot pressing process, the composite layer 15 not only touches or contacts the first bipolar plate 7a but also touches or contacts the second bipolar plate 7b, where these bipolar plates 7 are connected or joined to each other via the composite layer 15. It can also be seen that the second medium inlet channel 8c is axially and gastight covered by the second inlet sealing flange 6c that extends into or passes through the edge zone 5. A corresponding situation occurs on the opposite side 17a of the second bipolar plate 7b, where a second outlet sealing flange 6d that extends into or passes through the edge zone 5 is provided for axially and gastight covering the one or more second medium outlet channels 8d. In Figure 12 it can also be seen that the second reaction medium is guided onto the membrane electrode assembly 2 above the sealing structure 4 in the stacking direction. Correspondingly, the (partially) used second reaction medium is also led out of the single cell 11 or from the fuel cell stack 12 above the sealing structure 4 in the stacking direction.

[0062] In Figure 14 , that is Figure 13In the section XIV-XIV in FIG. 1 , the coolant flow field 13 c formed on the second bipolar plate 7 b and facing away from the membrane electrode assembly 2 can once again be seen.

[0063] exist Figure 15 It can be seen in the figure that the second bipolar plate 7b of the first single cell 11 and the first bipolar plate 7a of the other single cell 11 then form a complete channel cross section for passing the cooling medium. Here, the second bipolar plate 7b of the first single cell 11 and the first bipolar plate 7a of the other single cell 11 can also be joined to each other by a joining device or a joining medium.

[0064] The present shape allows the edge region 5 to be designed as narrow as possible in order to save expensive material of the bipolar plate 7. The selected configuration nevertheless ensures a reliable seal of each individual cell 11 and allows the active region 3 to be maximized compared to known individual cells.

[0065] exist Figure 16 In the figure, a fuel cell stack 12 formed by a plurality of individual cells 11 is shown by way of example. The fuel cell stack 12 has the following advantages: the bipolar plate 7 can be smaller in size compared to known bipolar plates, so that the manufacturing cost of the fuel cell stack 12 is reduced. In the present case, the bipolar plate 7 is rectangularly shaped, wherein the present invention is not dependent on the exact shape of the bipolar plate 7, but can also be applied without restriction to any shape with, for example, a circular or curved contour.

[0066] Since channels formed in the stacking direction or vertically within the bipolar plates 7 can be omitted, it is possible to supply reaction medium and / or cooling medium radially or laterally to or remove it from the individual cells or individual cells.

[0067] exist Figure 17A possible arrangement of the medium guiding device 22 is shown. Here, a medium guiding device 22 is provided that extends in the stacking direction and is mounted on the side of the fuel cell stack 12. These medium guiding devices 22 can be made of a material different from that of the bipolar plate 7, whereby the fuel cell stack 12 can be manufactured correspondingly advantageously. Two medium guiding devices 22a, 22b arranged on the short sides of these single cells supply anode gas (or hydrogen) to the anode region or anode of the membrane electrode assembly 2 or discharge the anode gas (or hydrogen) from the anode region or anode of the membrane electrode assembly 2. The medium guiding device 22c at the right rear supplies cathode gas to the cathode region or cathode of the membrane electrode assembly 2, while the (partially) used cathode gas is led out from the medium guiding device 22d at the left front on the long side of the bipolar plate 7. The medium guiding devices 22e, 22f at the left rear and at the right front on this long side are used to convey and discharge the cooling medium between the second bipolar plate 7b of the first single cell 11 and the first bipolar plate 7a of the second single cell 11 arranged adjacent to the first single cell 11.

[0068] List of reference numerals

[0069] 1 Fuel cell device

[0070] 2 Membrane electrode assembly (MEA)

[0071] 3 Active area

[0072] 4 Sealing structure

[0073] 5 Edge area

[0074] 6 Sealing flange

[0075] 6a First inlet sealing flange

[0076] 6b First outlet sealing flange

[0077] 6c Second inlet sealing flange

[0078] 6d Second outlet sealing flange

[0079] 7 Bipolar plate

[0080] 7a First bipolar plate

[0081] 7b Second bipolar plate

[0082] 8 Medium channel

[0083] 8a First medium inlet channel

[0084] 8b First medium outlet channel

[0085] 8c Second medium inlet channel

[0086] 8d Second medium outflow channel

[0087] 8e Coolant inlet channel

[0088] 8f Coolant outflow channel

[0089] 9a Short side of membrane electrode assembly

[0090] 9b Long side of membrane electrode assembly

[0091] 10 Sealing ring

[0092] 11 Single cell

[0093] 12 Fuel cell stack

[0094] 13a First flow field

[0095] 13b Second flow field

[0096] 13c Flow field (cooling medium)

[0097] 14 Wall

[0098] 15 Composite layer

[0099] 16 Empty space

[0100] 17a Long side of bipolar plate

[0101] 17b Short side of bipolar plate

[0102] 18 Contact line

[0103] 19 Protrusion

[0104] 20 Connection layer

[0105] 21 Overlap part

[0106] 22 Medium guiding device

[0107] 22a Medium guiding device

[0108] 22b Medium guiding device

[0109] 22c Medium guiding device

[0110] 22d Medium guiding device

[0111] 22e Medium guiding device

[0112] 22f Medium guiding device

Claims

1. A fuel cell device (1), the fuel cell device comprises a membrane electrode assembly (2), the membrane electrode assembly including a cathode, an anode, and a membrane disposed between the cathode and the anode; has an active area (3) substantially predefined by the membrane electrode assembly (2), in which the electrochemical reaction of the fuel cell takes place; and has a sealing structure (4) laterally assigned to the membrane electrode assembly (2), the sealing structure being configured such that reaction media only flow to where they are needed for the electrochemical reaction, wherein there is an edge area (5) predefined by the dimensions of adjacent bipolar plates (7), the edge area circumferentially limiting the active area (3), characterized in that the sealing structure (4) includes a sealing flange (6) extending into or passing through the edge area (5) outside the active area (3) for axially and gastight covering of a media channel (8) constructed in the adjacent bipolar plate (7) and within the edge area (5) and extending up to the edges (17a, 17b) of the bipolar plate (7), the media channel being configured to laterally transfer media into or out of the active area (3), and two of the sealing flanges (6) are arranged opposite each other on the shorter side (9a) of the membrane electrode assembly (2), while the other two of the sealing flanges (6) are arranged opposite each other and offset from each other on the longer side (9b) of the membrane electrode assembly (2).

2. The fuel cell device (1) according to claim 1, characterized in that the formed sealing structure (4) is dimensionally stable with respect to compressive and / or tensile stresses acting axially on the sealing structure.

3. The fuel cell device (1) according to claim 1, characterized in that the sealing flange (6) extends beyond the edge area (5).

4. The fuel cell device (1) according to any one of claims 1 to 3, characterized in that the sealing structure (4) has a sealing edge (10) sealing the membrane electrode assembly (2) laterally.

5. A single cell (11) for a fuel cell stack (12), the single cell having a fuel cell device (1) according to any one of claims 1 to 4 and having a first bipolar plate (7a), the first bipolar plate being arranged adjacent to the membrane electrode assembly (2), and the first bipolar plate including in the edge area (5) a media channel (8) axially and gastight covered by the sealing flange (6) and extending up to the edges (17a, 17b) of the bipolar plate (7), the media channel being configured to laterally transfer media into or out of the active area (3).

6. The single cell (11) according to claim 5, characterized in that the first bipolar plate (7a) includes in the edge area (5) a first media inlet channel (8a) and a first media outlet channel (8b); The first bipolar plate (7a) includes a first flow field (13a) in the active area (3) that is fluidly connected to the first medium inlet channel (8a) and the first medium outlet channel (8b). Moreover, the sealing structure (4) includes: a first inlet sealing flange (6a) extending into or through the edge area (5) for axially and airtightly covering the first medium inlet channel (8a); and a first outlet sealing flange (6b) extending into or through the edge area (5) for axially and airtightly covering the first medium outlet channel (8b).

7. The single cell (11) according to claim 6, characterized in that a second bipolar plate (7b) is provided, which includes a second medium inlet channel (8c) and a second medium outlet channel (8d); the second bipolar plate (7b) includes a second flow field (13b) that is fluidly connected to the second medium inlet channel (8c) and the second medium outlet channel (8d); moreover, the sealing structure (4) includes: a second inlet sealing flange (6c) extending into or through the edge area (5) for axially and airtightly covering the second medium inlet channel (8c); and a second outlet sealing flange (6d) extending into or through the edge area (5) for axially and airtightly covering the second medium outlet channel (8d).

8. The single cell (11) according to claim 7, characterized in that a composite layer (15) having a void portion (16) is provided between the first bipolar plate (7a) and the second bipolar plate (7b), and the composite layer is designed to laterally and airtightly seal the active area (3).

9. The single cell (11) according to claim 8, characterized in that the composite layer (15) is composed of multiple parts; and the first inlet sealing flange (6a) and the first outlet sealing flange (6b) project beyond the void portion (16) of the composite layer (15) to form a projecting portion (19).

10. The single cell (11) according to claim 9, characterized in that a connecting layer that forms an overlapping portion (21) with the composite layer (15) is coated onto the first inlet sealing flange (6a) and onto the first outlet sealing flange (6b).

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