Electrochemical device

Abstract

To create an electrochemical device comprising a stack of several electrochemical units arranged successively along a stacking direction, each unit comprising an electrochemically active membrane electrode assembly, a bipolar plate, and a sealing assembly, wherein the membrane electrode assembly comprises a cathode-side gas diffusion layer and an anode-side gas diffusion layer, and wherein the cathode-side gas diffusion layer is connected to a first sealing element and the anode-side gas diffusion layer is connected to a second sealing element of the sealing assembly, in which damage to areas of the membrane electrode assembly that are poorly contacted by the bipolar plates and / or damage to areas of the membrane electrode assembly where deposits accumulate during operation of the electrochemical device is reduced or preferably completely avoided, it is proposed thatthat at least one of the gas diffusion layers is provided on its circumference with at least one deactivation recess into which a deactivation area of ​​the sealing element to which the gas diffusion layer in question is attached extends.

Description

[0001] The present invention relates to an electrochemical device comprising a stack of several electrochemical units arranged one after the other along a stacking direction, each comprising an electrochemically active membrane electrode arrangement, a bipolar plate and a sealing arrangement, wherein the membrane electrode arrangement comprises a cathode-side gas diffusion layer and an anode-side gas diffusion layer, and wherein the cathode-side gas diffusion layer is connected to a first sealing element and the anode-side gas diffusion layer is connected to a second sealing element of the sealing arrangement.

[0002] Electrochemical devices of this type known from the prior art also include at least one medium channel extending along the stacking direction through several of the electrochemical units, at least one flow field through which a medium can flow from the medium channel transversely to the stacking direction from the medium channel to another medium channel, and at least one connecting channel through which the flow field and the medium channel are in fluid communication with each other.

[0003] The membrane electrode arrangement of each electrochemical unit is supported on a first side by the bipolar plate of the electrochemical unit in question and on a second side opposite the first side by the bipolar plate of another electrochemical unit adjacent to this electrochemical unit.

[0004] The bipolar plates adjacent to the membrane electrode arrangement are often composed of two layers of bipolar plates, which are joined together at partial contact points by a material bond - usually by welding - in order to spatially seal the various gaseous media required for the operation of the electrochemical device against each other.

[0005] These partial contact points result in areas of the membrane electrode arrangement that are less well supported by the adjacent bipolar plates.

[0006] Furthermore, at various points in the membrane electrode assembly, particularly in the areas where the connecting channels leading from the medium channels of the electrochemical device to the respective flow fields open into the flow fields, deposits accumulate during the operation of the electrochemical device. At these points in the membrane electrode assembly where deposits accumulate, damage to the assembly, in particular leakage of the membrane, can occur.

[0007] In areas of the membrane electrode assembly that are less well supported by the bipolar plates, the heat generated by the electrochemical reaction in the membrane electrode assembly cannot be dissipated as effectively, which can also lead to damage to the membrane electrode assembly in these areas.

[0008] The aforementioned damage to the membrane electrode assembly, which can result in internal leakage of the membrane electrode assembly, can lead to premature failure of the stack of electrochemical units.

[0009] The present invention is based on the objective of creating an electrochemical device of the type mentioned above in which damage to areas of the membrane electrode arrangement that are poorly contacted by the bipolar plates and / or damage to areas of the membrane electrode arrangement where deposits accumulate during operation of the electrochemical device is reduced or preferably completely avoided.

[0010] This problem is solved in an electrochemical device with the features of the preamble of claim 1 according to the invention in that at least one of the gas diffusion layers is provided on its circumference with at least one deactivation recess into which a deactivation area of ​​the sealing element to which the gas diffusion layer in question is attached extends.

[0011] The present invention is based on the concept that by preventing cathode gas and / or anode gas from reaching the membrane of the membrane electrode assembly in the area of ​​the deactivation recess of the gas diffusion layer, the electrochemical reaction in the area of ​​the deactivation recess is prevented, thereby avoiding damage to the membrane electrode assembly in the relevant area of ​​the membrane electrode assembly.

[0012] Such a deactivation recess of the gas diffusion layer is preferably arranged at the points of the membrane electrode arrangement that are poorly contacted by the bipolar plates and / or at the points where an accumulation of deposits can occur due to the inflow of a fluid from a connecting channel of the electrochemical unit.

[0013] The electrochemical device according to the invention can, for example, be designed as a fuel cell device, as an electrolyzer or as an electrochemical compressor.

[0014] In the solution according to the invention, deactivation of an area of ​​the membrane electrode arrangement is achieved by notching out at least one of the gas diffusion layers, i.e. the cathode-side gas diffusion layer and / or the anode-side gas diffusion layer of the membrane electrode arrangement, and filling the notch with sealing material, in particular with an elastomer material.

[0015] An alternative solution, in which the relevant area of ​​the membrane-electrode assembly is deactivated by applying additional sealing material, in particular additional elastomeric material, to a top surface of at least one of the gas diffusion layers facing away from the membrane of the membrane-electrode assembly, has the disadvantage that the height of the flow channels in the adjacent flow field of the bipolar plate must be reduced. Furthermore, the additionally applied sealing material, in particular elastomeric material, has a very small height (i.e., a very small extent along the stacking direction of the electrochemical device) and must achieve a very large overlap width relative to this height in a projection direction perpendicular to the circumferential direction of the gas diffusion layer.When the sealing element is joined to the gas diffusion layer in an injection molding process, the injection pressure within the cavity of the injection mold must be increased to fill this very shallow and wide space with the sealing material, particularly the elastomer. This higher injection pressure allows the sealing material, especially the elastomer, to penetrate the gas diffusion layer more extensively at its outer edge. This, in turn, reduces the electrochemically active area of ​​the membrane-electrode assembly at other points along the edge of the gas diffusion layer due to the sealing material penetrating the layer, thus unnecessarily reducing the performance of the electrochemical unit.

[0016] In the solution according to the invention, in which the deactivation area of ​​the sealing element overlaps the gas diffusion layer in the edge region of the deactivation recess only slightly and preferably not at all, these disadvantages are reduced or completely avoided.

[0017] Preferably, the deactivation area of ​​the sealing element substantially covers a cross-sectional area of ​​the deactivation recess measured perpendicular to the stacking direction. This prevents any gap from forming between the gas diffusion layer and the deactivation area of ​​the sealing element, through which cathode gas or anode gas could directly reach the membrane of the membrane electrode assembly.

[0018] In a preferred embodiment of the invention, an outer edge surface of the gas diffusion layer facing the deactivation area of ​​the respective sealing element is oriented essentially parallel to the stacking direction. In this case, the gas diffusion layer is connected to the end face of the deactivation area of ​​the respective sealing element at its outer edge surface.

[0019] To prevent over-compression by additional sealing material, especially elastomer material, it is advantageous if the deactivation area of ​​the sealing element in question protrudes by less than the height (H) of the gas diffusion layer above the upper surface of the gas diffusion layer facing away from the other gas diffusion layer.

[0020] It is particularly advantageous if the deactivation area of ​​the relevant sealing element extends less than half the height (H) of the gas diffusion layer, for example less than a quarter of the height (H) of the gas diffusion layer, beyond the upper surface of the gas diffusion layer facing away from the other gas diffusion layer.

[0021] In a preferred embodiment of the invention, it is provided that the deactivation area of ​​the relevant sealing element is essentially flush with the upper surface of the gas diffusion layer facing away from the other gas diffusion layer.

[0022] It has proven particularly advantageous if at least one deactivation recess is provided in the cathode-side gas diffusion layer.

[0023] Alternatively or additionally, it may also be provided that at least one deactivation recess is provided in the anode-side gas diffusion layer.

[0024] In a particular embodiment of the invention, at least one first deactivation recess is provided in the cathode-side gas diffusion layer and at least one second deactivation recess is provided in the anode-side gas diffusion layer, wherein the first deactivation recess and the second deactivation recess overlap each other at least partially, preferably substantially completely, when projected along the stacking direction of the electrochemical device.

[0025] If the electrochemical device has at least one medium channel extending along the stacking direction through several of the electrochemical units, at least one flow field through which a medium can flow from the medium channel transversely to the stacking direction from the medium channel to another medium channel, and at least one connecting channel through which the flow field and the medium channel are in fluid communication with each other, includes It is preferably provided that at least one deactivation recess is arranged where such a connecting channel opens into a flow field of the electrochemical unit, because at these points the risk is particularly high that an accumulation of deposits will occur during the operation of the electrochemical device and that this accumulation of deposits will lead to damage to the membrane electrode arrangement.

[0026] In a particular embodiment of the electrochemical device, it is provided that at least one deactivation recess comprises several partial recesses which are spaced apart from each other along the circumferential direction of the gas diffusion layer, wherein the sealing element to which the gas diffusion layer is attached overlaps an intermediate area of ​​the gas diffusion layer located between the partial recesses - viewed in the stacking direction.

[0027] According to the present invention, the weak points of the membrane electrode assembly, where leaks could preferably occur, are deliberately not supplied with cathode gas and / or anode gas. This is achieved by partially removing the cathode-side gas diffusion layer and / or the anode-side gas diffusion layer at these weak points or critical areas of the membrane electrode assembly.

[0028] While a sealing element of the sealing assembly typically overlaps the associated gas diffusion layer, in the present invention the gas diffusion layer is recessed or notched and preferably connected to the sealing material of the sealing element at its end face. This eliminates the need to lower the height of the flow channels of the flow fields adjacent to the membrane-electrode assembly and avoids partial over-compression of the membrane-electrode assembly and / or the sealing element of the sealing assembly.

[0029] The height (that is, the extent along the stacking direction of the electrochemical device) of the sealing element in the area of ​​the end-face connection to the gas diffusion layer can, in principle, be chosen arbitrarily. For example, the sealing element in the area of ​​the end-face connection to the gas diffusion layer can have a lower height than the gas diffusion layer in its compressed state.

[0030] Preferably, however, the sealing element is in its deactivation area The deactivation area of ​​the sealing element must be at least as high as the gas diffusion layer at the edge of the deactivation recess. It can be flush with the upper surface of the gas diffusion layer facing away from the membrane of the membrane-electrode assembly, or it can extend beyond this upper surface to achieve a certain degree of compression of the sealing element when the electrochemical device is assembled. In the latter case, the deactivation area of ​​the sealing element may also slightly overlap the edge of the deactivation recess in the gas diffusion layer.

[0031] The at least one deactivation recess in the gas diffusion layer is preferably designed such that it overlaps only the weak point of the membrane-electrode assembly that is to be deactivated. The assembly tolerances of the electrochemical device are preferably also taken into account when selecting the position and size of the deactivation recess.

[0032] Each deactivation recess can extend continuously in the circumferential direction of the gas diffusion layer.

[0033] Alternatively, at least one deactivation recess can be provided with several partial recesses spaced apart along the circumferential direction of the gas diffusion layer. Dividing the deactivation recess into several partial recesses makes the assembly consisting of the gas diffusion layer and the associated sealing element of the sealing arrangement more stable for the manufacturing process, since the sealing element to which the gas diffusion layer is attached overlaps an intermediate area of ​​the gas diffusion layer located between the partial recesses – viewed in the stacking direction of the electrochemical device – thus strengthening the mechanical connection between the sealing element and the gas diffusion layer.

[0034] In the areas of the membrane electrode arrangement adjacent to the opening of a connecting channel into the flow field of a neighboring bipolar plate, one or more deactivation recesses can be provided along the circumference of the gas diffusion layer. These recesses can cover the entire opening area of ​​the connecting channel or only parts of it. The deactivation recesses in the gas diffusion layer can be arranged at any possible distance from one another and can have any possible configuration or combination of different configurations.

[0035] Further features and advantages of the invention are the subject of the following description and the graphic representation of exemplary embodiments.

[0036] The drawings show: Fig. 1 a schematic perspective representation of a boundary region of a membrane electrode arrangement of an electrochemical unit, which is connected to a sealing arrangement of the electrochemical unit, wherein the membrane electrode arrangement comprises a cathode-side gas diffusion layer which is connected to a first sealing element of the sealing arrangement, and an anode-side gas diffusion layer which is connected to a second sealing element of the sealing arrangement; Fig. 2 a schematic longitudinal section through the edge region of the membrane electrode arrangement and the sealing arrangement made of Fig. 1; Fig. 3 A schematic perspective representation of the edge area of ​​the cathode-side gas diffusion layer and the first sealing element of the sealing arrangement from the Fig. 1 and Fig. 2; Fig. 4 a partial longitudinal section through the edge area of ​​the cathode-side gas diffusion layer and the first sealing element of the sealing arrangement made of Fig. 3; Fig. 5 a schematic perspective representation of an edge region of a cathode-side gas diffusion layer and a first sealing element of a sealing arrangement of an electrochemical unit in a first embodiment of an electrochemical device according to the invention, wherein the gas diffusion layer is provided on its circumference with a deactivation recess into which a deactivation area of ​​the sealing element, to which the gas diffusion layer is connected, extends such that the deactivation area of ​​the sealing element substantially completely covers the cross-sectional area of ​​the deactivation recess of the gas diffusion layer taken perpendicular to the stacking direction; Fig. 6 a partial top view along the stacking direction from above of the edge region of the cathode-side gas diffusion layer, which has a deactivation recess, and the first sealing element, which has a deactivation area, from the Fig. 5; Fig. 7 a partial longitudinal section through the edge region of the cathode-side gas diffusion layer and the first sealing element of the sealing arrangement in the area of ​​the deactivation recess of the gas diffusion layer and the deactivation area of ​​the sealing element, along line 7 - 7 in Fig. 6; Fig. 8 A schematic perspective view of an edge region of a cathode-side gas diffusion layer and a first sealing element of a sealing arrangement of an electrochemical unit in a second embodiment of an electrochemical device according to the invention, in which the gas diffusion layer is provided on its circumference with a deactivation recess which comprises several partial recesses spaced apart from one another along the circumferential direction of the gas diffusion layer, wherein the sealing element comprises a deactivation area which includes two partial areas which each extend into one of the partial recesses of the deactivation recess of the gas diffusion layer and preferably substantially completely cover the cross-sectional area of ​​the respective partial recess of the deactivation recess taken perpendicular to the stacking direction,and wherein the first sealing element overlaps an intermediate area of ​​the gas diffusion layer located between the partial recesses of the deactivation recess of the gas diffusion layer - viewed in the stacking direction; Fig. 9 a partial top view along the stacking direction from above of the edge area of ​​the cathode-side gas diffusion layer and the first sealing element of the sealing arrangement made of Fig. 8; and Fig. 10 a partial longitudinal section through the cathode-side gas diffusion layer and the first sealing element of the sealing arrangement made of Fig. 9 in the area of ​​one of the partial recesses of the deactivation recess of the gas diffusion layer and a partial area of ​​the deactivation area of ​​the sealing element, along line 10 - 10 in Fig. 9.

[0037] Identical or functionally equivalent elements are designated with the same reference symbols in all figures.

[0038] One in the Fig. 1, Fig. 2, Fig. 3 to Fig. 4 The electrochemical device 100 shown comprises several electrochemical units 102 which follow one another along a stacking direction 104 of the electrochemical device 100.

[0039] Each electrochemical unit 102, of which in the Fig. 1, Fig. 2, Fig. 3 to Fig. 4, which is shown only in part, comprises a membrane electrode assembly (MEA) 106, which in turn comprises a first gas diffusion layer 108, a membrane 109 and a second gas diffusion layer 110.

[0040] Preferably, the first gas diffusion layer 108 is a cathode-side gas diffusion layer and the second gas diffusion layer 110 is an anode-side gas diffusion layer.

[0041] Furthermore, each electrochemical unit 102 comprises a sealing arrangement 112 and a (not shown) bipolar plate.

[0042] In this embodiment, the sealing arrangement 112 comprises a first sealing element 116, which is preferably materially bonded to the first gas diffusion layer 108, and a second sealing element 118, which is preferably materially bonded to the second gas diffusion layer 110.

[0043] The first sealing element 116 and / or the second sealing element 118 is preferably made of an elastomeric material.

[0044] The first sealing element 116 comprises, in the Fig. 1, Fig. 2, Fig. 3 to Fig. In the embodiment shown in Figure 4, two first sealing lips 120 are provided, wherein the dome of the first sealing lip 120a located closer to the first gas diffusion layer 108 forms a first inner sealing line 122a of the sealing arrangement 112 and the dome of the first sealing lip 120b located further away from the first gas diffusion layer 108 forms a first outer sealing line 122b of the sealing arrangement 112.

[0045] The sealing lines 122a and 122b extend parallel to a circumferential direction 124 of the membrane-electrode arrangement 106, which runs parallel to the outer edges 126a, 126b of the first gas diffusion layer 108 and the second gas diffusion layer 110 respectively, and parallel to the outer edge 128 of the membrane 109.

[0046] With the sealing lines 122a and 122b, the sealing arrangement 112, in the assembled state of the electrochemical device 100, rests against the (not shown) bipolar plate of the electrochemical unit 102 in a fluid-tight sealing manner.

[0047] The second sealing element 118 of the sealing arrangement 112 comprises, in the Fig. 1, Fig. 2, Fig. 3 to Fig. In the embodiment shown in Figure 4, two second sealing lips 130 are provided, wherein the tip of the second sealing lip 130a located closer to the second gas diffusion layer 110 forms a second inner sealing line 132a of the sealing arrangement 112 and the tip of the second sealing lip 130b located further away from the second gas diffusion layer 110 forms a second outer sealing line 132b of the sealing arrangement 112.

[0048] The sealing lines 132a and 132b run parallel to the circumferential direction 124 of the membrane electrode arrangement 106.

[0049] With the sealing lines 132a and 132b, the sealing arrangement 112, in the assembled state of the electrochemical device 100, rests fluid-tight against a (not shown) bipolar plate of another electrochemical unit 102 adjacent to the electrochemical unit 102 of the electrochemical device 100.

[0050] The first sealing element 116 extends in a projecting direction 134, which is oriented perpendicular to the stacking direction 104 and perpendicular to the circumferential direction 124 of the membrane electrode arrangement 106, with an overlap area 136 over an outer edge region of the first gas diffusion layer 108.

[0051] The second sealing element 118 extends along the projection direction 134 with an overlap area 138 over an outer edge area of ​​the second gas diffusion layer 110.

[0052] The in the Fig. 1, Fig. 2, Fig. 3 to Fig. The areas of the sealing arrangement 112 shown in Figure 4, in particular the first sealing lips 120, the second sealing lips 130 and the overlapping areas 136 and 138 of the sealing elements 116 and 118, together form a flow field area 140 of the sealing arrangement 112, which extends in a ring-shaped closed shape around the membrane electrode arrangement 106 and the flow fields for a cathode gas or an anode gas of the electrochemical device 100 formed on both sides of the membrane electrode arrangement 106 on the respective adjacent bipolar plates.

[0053] The bipolar plates adjacent to the membrane electrode arrangement 106 are composed of two layers of bipolar plates which are joined together at partial contact points by material bonding - preferably by welding - in order to spatially seal the various gaseous media required for the operation of the electrochemical device 100 against each other.

[0054] These partial contact points result in areas of the membrane electrode arrangement 106 that are less well supported by the adjacent bipolar plates.

[0055] Furthermore, deposits accumulate at various points in the membrane electrode assembly 106, particularly in the areas where connecting channels leading from the medium channels of the electrochemical device 100 to the respective associated flow fields open into the flow fields. At these points in the membrane electrode assembly 106, where deposits accumulate during operation of the electrochemical device 100, damage to the membrane electrode assembly 106, in particular leakage of the membrane 109, can occur.

[0056] At the points of the membrane electrode assembly 106 that are less well supported by the bipolar plates, the heat generated by the electrochemical reaction in the membrane electrode assembly 106 cannot be dissipated as well, which can also lead to damage to the membrane electrode assembly 106 in these areas.

[0057] The aforementioned damage to the membrane electrode assembly, which may result in an internal leakage of the membrane electrode assembly 106, may lead to premature failure of the stack of electrochemical units 102.

[0058] During a session in the Fig. 5, Fig. 6 to Fig. In the partial illustration of the embodiment of an electrochemical device 100 according to the invention, such damage to areas poorly contacted by the bipolar plates and / or to areas of the membrane electrode arrangement 106 where deposits accumulate during operation of the electrochemical device 100 is reduced or preferably completely avoided by electrochemically deactivating these vulnerable areas of the membrane electrode arrangement 106.

[0059] This deactivation occurs because an area of ​​one of the gas diffusion layers 108, 110, in which in the Fig. 5, Fig. 6 to Fig. In the embodiment shown in Figure 7, the first gas diffusion layer 108 is partially removed and the area from which the gas diffusion layer 108 has been removed is filled with the material of the sealing arrangement 112, in particular with an elastomer material.

[0060] As from the Fig. 5 and Fig. As can be seen in Figure 6, for this purpose the first gas diffusion layer 108 is provided on its circumference with at least one deactivation recess 142, into which a deactivation area 144 of the first sealing element 116, to which the first gas diffusion layer 108 is materially bonded, extends.

[0061] The deactivation area 144 of the sealing element 116 essentially completely covers the cross-sectional area of ​​the deactivation recess 142, which is perpendicular to the stacking direction 104.

[0062] How best to Fig. As can be seen in Figure 7, the gas diffusion layer 108 is connected at the end face to the deactivation area 144 of the sealing element 116 in the area of ​​the deactivation recess 142, so that an outer edge surface 146 of the gas diffusion layer 108 facing the deactivation area 144 of the sealing element 116 is oriented essentially parallel to the stacking direction 104.

[0063] The deactivation area 144 of the sealing element 108 preferably closes essentially flush with the upper surface 148 of the gas diffusion layer 108 connected to the respective sealing element 116, which faces away from the other gas diffusion layer 110.

[0064] In one variant of the in the Fig. 5, Fig. 6 to Fig. In the embodiment of an electrochemical device 100 shown in Figure 7, the height h of the sealing element 116 in the deactivation area 144 can also be adjusted so that the deactivation area 144 of the sealing element 116 extends along the stacking direction 104 beyond the top surface 148 of the gas diffusion layer 108 in order to achieve a certain compression of the deactivation area 144 during the assembly of the electrochemical device 100.

[0065] Preferably, however, the deactivation area 144 of the sealing element 116 protrudes by less than the height H of the gas diffusion layer 108 in the pressed-in assembled state, in particular by less than half the height H of the gas diffusion layer 108, and especially preferably by less than a quarter of the height H of the gas diffusion layer 108, beyond the upper surface 148 of the gas diffusion layer 108 facing away from the other gas diffusion layer 110.

[0066] In another variant of the in the Fig. 5, Fig. 6 to Fig. In the embodiment of an electrochemical device 100 shown in Figure 7, it is provided that the height h of the deactivation area 144 of the sealing element 116 of the sealing arrangement 112 in the pressed-in assembled state is lower than the height H of the gas diffusion layer 108 in the pressed-in assembled state.

[0067] As in the Fig. 5, Fig. 6 to Fig. As shown in Figure 7, the deactivation recess 142 is preferably provided in the cathode-side gas diffusion layer 108.

[0068] Alternatively or additionally, it may also be provided that such a deactivation recess 142 is provided on the circumference of the anode-side gas diffusion layer 110.

[0069] In a special embodiment, not shown in the drawing, a first deactivation recess 142 is provided in the cathode-side gas diffusion layer 108 and a second deactivation recess 142 is provided in the anode-side gas diffusion layer 110.

[0070] In this case, it can be provided in particular that the first deactivation recess 142 and the second deactivation recess 142 overlap each other at least partially, preferably substantially completely, when projected along the stacking direction 104.

[0071] How best to Fig. As can be seen in Figure 6, the deactivation recess 142 on the circumference of the gas diffusion layer 108 preferably has a trapezoidal cross-section (preferably with rounded corner areas) taken perpendicular to the stacking direction 104.

[0072] Several such deactivation recesses 142 can follow one another at intervals along the perimeter of the gas diffusion layer 108.

[0073] By preventing cathode gas from reaching the membrane 109 of the membrane electrode assembly 106 in the area of ​​the deactivation recesses 142 of the gas diffusion layer 108, damage to the membrane electrode assembly 106 at a vulnerable location of the membrane electrode assembly 106 covered by the deactivation area 144 of the sealing element 116, for example at a location of the membrane electrode assembly 106 that is poorly contacted by the bipolar plates and / or at a location where deposits accumulate due to the inflow of a fluid medium from a connecting channel of the electrochemical unit 102, is avoided.

[0074] One in the Fig. 8, Fig. 9 to Fig. The second embodiment of an electrochemical device 100, shown in partial detail in Figure 10, differs from the one shown in the Fig. 5, Fig. 6 to Fig. 7 first embodiment in which at least one of the deactivation recesses 142 on the circumference of the first gas diffusion layer 108 is not continuous, but comprises several partial recesses 150a, 150b which are spaced apart from each other along the circumferential direction 124 of the gas diffusion layer 108, wherein the first sealing element 116, to which the first gas diffusion layer 108 is connected, overlaps an intermediate area 152 of the first gas diffusion layer 108 lying between the partial recesses 150a and 150b - seen in the stacking direction 104.

[0075] How best to Fig. As can be seen in Figure 9, the partial recesses 150a, 150b on the circumference of the gas diffusion layer 108 preferably have a triangular cross-section (preferably with rounded corner areas) taken perpendicular to the stacking direction 104.

[0076] Into each of the partial recesses 150a, 150b of the deactivation recess 142 of the gas diffusion layer 108, a partial area 154a, 154b of the deactivation area 144 of the sealing element 116 extends such that the respective partial area 154a, 154b substantially completely covers a cross-sectional area of ​​the respective assigned partial recess 150a, 150b taken perpendicular to the stacking direction 104.

[0077] Moreover, the one in the Fig. 8, Fig. 9 to Fig. Figure 10 shows the second embodiment of an electrochemical device 100 according to the invention with regard to its structure, function and method of manufacture, compared to the one described in the Fig. 5, Fig. 6 to Fig. 7 shown in the first embodiment according to the invention, to the preceding description of which reference is made in this respect.

Claims

[1] Electrochemical device comprising a stack of several electrochemical units (102) arranged in succession along a stacking direction (104), each comprising an electrochemically active membrane electrode arrangement (106), a bipolar plate and a sealing arrangement (112), wherein the membrane electrode arrangement (106) comprises a cathode-side gas diffusion layer (108) and an anode-side gas diffusion layer (110) and wherein the cathode-side gas diffusion layer (108) is connected to a first sealing element (116) and the anode-side gas diffusion layer (110) is connected to a second sealing element (118) of the sealing arrangement (112), characterized by , that at least one of the gas diffusion layers (108; 110) is provided on its circumference with at least one deactivation recess (142) into which a deactivation area (144) of the sealing element (116), to which the gas diffusion layer (108) is connected, extends. [2] Electrochemical device according to claim 1, characterized by , that the deactivation area (144) of the sealing element (116) substantially completely covers a cross-sectional area of ​​the deactivation recess (142) taken perpendicular to the stacking direction (104). [3] Electrochemical device according to claim 1 or 2, characterized by , that an outer edge surface (146) of the gas diffusion layer (108) facing the deactivation area (144) of the sealing element (116) in question is oriented essentially parallel to the stacking direction (104). [4] Electrochemical device according to any one of claims 1 to 3, characterized by, that the deactivation area (144) of the relevant sealing element (116) protrudes by less than the height (H) of the gas diffusion layer (108) above the upper surface (148) of the gas diffusion layer (108) facing away from the other gas diffusion layer (110). [5] Electrochemical device according to any one of claims 1 to 4, characterized by , that the deactivation area (144) of the relevant sealing element (116) is essentially flush with the upper surface (148) of the gas diffusion layer (108) facing away from the other gas diffusion layer (110). [6] Electrochemical device according to any one of claims 1 to 5, characterized by , that at least one deactivation recess (142) is provided in the cathode-side gas diffusion layer (108). [7] Electrochemical device according to any one of claims 1 to 6, characterized by , that at least one deactivation recess (142) is provided in the anode-side gas diffusion layer (110). [8] Electrochemical device according to any one of claims 1 to 7, characterized by , that at least one first deactivation recess (142) is provided in the cathode-side gas diffusion layer (108) and at least one second deactivation recess (142) is provided in the anode-side gas diffusion layer (110), wherein the first deactivation recess (142) and the second deactivation recess (142) overlap each other at least partially when projected along the stacking direction (104). [9] Electrochemical device according to any one of claims 1 to 8, characterized by , that the electrochemical device (100) has at least one medium channel extending along the stacking direction (104) through several of the electrochemical units (102), at least one flow field through which a medium can flow from the medium channel transversely to the stacking direction (104) from the medium channel to another medium channel, and includes at least one connecting channel through which the flow field and the medium channel are in fluid communication with each other, wherein at least one deactivation recess (142) is arranged where a connecting channel opens into a flow field of the electrochemical unit (102). [10] Electrochemical device according to any one of claims 1 to 9, characterized by , that at least one deactivation recess (142) comprises several partial recesses (150a, 150b) which are spaced apart from each other along the circumferential direction (124) of the gas diffusion layer (108), wherein the sealing element (116) to which the gas diffusion layer (108) is attached overlaps an intermediate area (152) of the gas diffusion layer (108) located between the partial recesses (150a, 150b) - as seen in the stacking direction (104).

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