Method for assembling stack of electrochemical cells of electrochemical device and electrochemical device

Abstract

In order to provide a method for assembling a stack of electrochemical cells of an electrochemical device, the electrochemical cells following one behind the other in the stacking direction, and each electrochemical cell comprising a bipolar plate and a sealing assembly, whereby an unsealing between the sealing assembly and an adjacent bipolar plate is reliably avoided, the invention proposes that the sealing assembly comprises a plurality of sealing elements, the method comprises the following steps: a) providing bipolar plates each having a primary side and a secondary side; b) providing a sealing assembly having a primary side and a secondary side, respectively; c) contacting the main side of the seal assembly with the main side of the adjacent first bipolar plate, where the main side of the seal assembly and the main side of the bipolar plate are positioned relative to each other to follow a first offset tolerance; the secondary sides of the sealing assemblies and the secondary sides of the bipolar plates are positioned relative to each other to follow a second offset tolerance, repeating steps c) and d) until all the sealing assemblies are in contact with the bipolar plates to be in contact respectively, the first offset tolerance being smaller than the second offset tolerance.

Description

Field of the Invention

[0001] The present invention relates to a method for assembling a stack composed of electrochemical cells of an electrochemical device, wherein the electrochemical cells follow one another in a stacking direction, and wherein each electrochemical cell includes a bipolar plate and a sealing assembly. Background Art

[0002] The electrochemical device can be, for example, a fuel cell device or an electrolyzer.

[0003] Each electrochemical cell can be, for example, a fuel cell unit or an electrolysis unit.

[0004] Such an electrochemical device can be referred to, for example, in the patent document DE 10 2014 104 017 A1.

[0005] If, when assembling a stack composed of electrochemical cells of an electrochemical device, the bipolar plate and the sealing assembly of the electrochemical cell are not precisely positioned relative to each other, the structure of the bipolar plate may meet the structure of the sealing assembly, resulting in a lack of tightness between the relevant sealing assembly and the relevant bipolar plate.

[0006] The structure formed on the bipolar plate can be, for example, a recess of the bipolar plate.

[0007] The structure formed on the sealing assembly can be, for example, a sealing lip of the sealing assembly.

[0008] If the sealing lip does not abut against the substantially flat sealing surface of the bipolar plate due to an offset of the bipolar plate and the sealing assembly in a transverse direction perpendicular to the stacking direction, but reaches the structural area, especially the recessed area, of the bipolar plate, it will result in a lack of tightness between the sealing assembly and the bipolar plate.

[0009] In known electrochemical devices, each bipolar plate includes two bipolar plate layers, which are connected to each other by material locking, for example, by welding, so that all structural elements of the two bipolar plate layers are positioned relative to each other without offset.

[0010] The sealing assembly has a sealing lip that abuts against the substantially flat sealing surface of the bipolar plate.

[0011] The center line of the sealing lip apex defines a sealing line. When all components of the stack composed of electrochemical cells are assembled without offset from each other, the sealing assembly abuts tightly against the bipolar plate in a fluid-tight manner along the sealing line.

[0012] The two bipolar plate layers of each bipolar plate are substantially mirror-symmetrical with respect to the main plane of the bipolar plate oriented perpendicular to the stacking direction in the region where the sealing assembly abuts tightly against the bipolar plate with its sealing lip.

[0013] Both of the two bipolar plate layers have support elements, and the two bipolar plate layers are in contact with and support each other at the support elements. These support elements are all configured to be recessed, and the recesses are opposed to the bipolar plate sealing surfaces adjacent to the recesses.

[0014] Preferably, the distances between the sealing lines of the sealing assembly and the nearest recesses are all substantially the same.

[0015] If, when assembling a stack composed of electrochemical cells, the sealing assembly is offset relative to the bipolar plate in a lateral direction oriented perpendicular to the stack direction, the sealing line of the sealing lip may at least partially slide into the area of the support element configured as a recess. Thus, the sealing function of the relevant sealing line cannot be guaranteed.

[0016] Not only may the sealing assembly as a whole be offset relative to the bipolar plate, but also different elastomeric sealing elements in the same sealing assembly may be offset relative to each other in the lateral direction.

[0017] In principle, the two bipolar plate layers of the bipolar plate may also be joined with an offset relative to each other. Summary of the Invention

[0018] The object of the present invention is to provide a method for assembling a stack composed of electrochemical cells of an electrochemical device of the type described at the beginning, wherein, even when there is an offset when assembling the bipolar plate and the sealing assembly in a lateral direction oriented perpendicular to the stack direction, and / or there is an offset tolerance when sub-components of the bipolar plate and / or the sealing assembly are assembled relative to each other in the lateral direction, the airtightness between the sealing assembly and the adjacent bipolar plate can be reliably avoided.

[0019] This object is solved by a method for assembling a stack composed of electrochemical cells of an electrochemical device according to claim 1, wherein the electrochemical cells follow one another in the stack direction, and wherein each electrochemical cell includes a bipolar plate and a sealing assembly, and the method includes the following steps:

[0020] a) Providing bipolar plates, each of which has a main side and a secondary side facing away from the main side;

[0021] b) Providing a sealing assembly, which has a main side and a secondary side facing away from the main side;

[0022] c) Bringing the main side of the sealing assembly into contact with the main side of the adjacent first bipolar plate, wherein the main side of the sealing assembly and the main side of the adjacent first bipolar plate are positioned relative to each other to follow a first offset tolerance in a lateral direction oriented perpendicular to the stack direction;

[0023] d) Bring the secondary side of the sealing assembly into contact with the secondary side of the adjacent second bipolar plate, wherein the secondary side of the sealing assembly and the secondary side of the adjacent second bipolar plate are positioned relative to each other to follow a second offset tolerance in the lateral direction;

[0024] - Repeat steps c) and d) until all the sealing assemblies are in contact with the bipolar plates to be contacted respectively;

[0025] Wherein, the first offset tolerance is less than the second offset tolerance.

[0026] Each bipolar plate can be formed in one piece or formed by at least two bipolar plate layers.

[0027] Each sealing assembly can be formed in one piece or composed of multiple elastomeric sealing elements.

[0028] The components arranged on the primary side of the bipolar plate act as primary members or reference members for positioning the respective bipolar plates in the stack.

[0029] The components arranged on the primary side of the sealing assembly are used as primary members or reference members for positioning the relevant sealing assembly in the stack composed of electrochemical cells.

[0030] Hereinafter, the components arranged on the secondary side of the bipolar plate are referred to as bipolar plate secondary members.

[0031] Hereinafter, the components arranged on the secondary side of the sealing assembly are referred to as secondary members of the sealing assembly.

[0032] All the components of the bipolar plate and the sealing assembly have structures that must be oriented and positioned relative to each other to ensure the function of the stack composed of electrochemical cells, especially the sealing of the electrochemically active units of the electrochemical cells. These structures must be positioned relative to each other very precisely. In particular, these structures can be configured as sealing lines in the regions of the flow ports or connection channels of the electrochemical cells.

[0033] Such flow ports or connection channels establish a fluid connection between the medium channels passing through the electrochemical device in the stack direction and the flow fields of the bipolar plates for the relevant fluid media, feeding the fluid media into the electrochemical cells of the electrochemical device through the medium channels or discharging the fluid media from the electrochemical cells of the electrochemical device through the medium channels.

[0034] When assembling the stack composed of the electrochemical cells of the electrochemical device, place the primary member or reference member of the bipolar plate on the primary member or reference member of the sealing assembly or the membrane electrode assembly, or place the primary member or reference member of the sealing assembly or the membrane electrode assembly on the primary member of the bipolar plate.

[0035] Here, the reference system of the main component of the bipolar plate is precisely oriented and positioned relative to the reference system of the main component of the sealing assembly or the membrane electrode assembly with respect to each other.

[0036] The main component or the reference component of the bipolar plate and the sealing assembly or the membrane electrode assembly have a relatively small first offset tolerance with respect to each other in the lateral direction of the electrochemical device that is oriented perpendicular to the stacking direction.

[0037] The bipolar plate is positioned relative to the secondary component of the sealing assembly or the membrane electrode assembly to follow a relatively large second offset tolerance in the lateral direction that is oriented perpendicular to the stacking direction.

[0038] An advantage of one aspect of the present invention is that the structure of the bipolar plate and the structure of the sealing assembly or the membrane electrode assembly are distributed onto the main side and the secondary side of the bipolar plate or the sealing assembly or the membrane electrode assembly, such that the structures that are critical for the sealing function are only in positions where they can follow a narrow offset tolerance, namely, on the main side of the bipolar plate and on the main side of the sealing assembly or the membrane electrode assembly.

[0039] Conversely, the secondary side of the bipolar plate and the secondary side of the sealing assembly or the membrane electrode assembly (which are assembled with respect to each other with a relatively large offset tolerance in the lateral direction) preferably do not have structures that are critical for the sealing.

[0040] For example, it can be provided that the secondary side of the bipolar plate is configured to be substantially flat, i.e., in particular, is not configured with recessed support elements.

[0041] Alternatively or additionally, it can be provided that the secondary side of the sealing assembly or the membrane electrode assembly is configured to be substantially flat, i.e., in particular, is not configured with sealing lips.

[0042] The offset tolerance between the secondary side of the bipolar plate and the secondary side of the sealing assembly or the membrane electrode assembly is greater than the offset tolerance between the main side of the bipolar plate or the main side of the sealing assembly and the membrane electrode assembly, because in the offset tolerance of the secondary side, in addition to the stacking offset that occurs due to the assembly of the electrochemical unit, additional offsets also occur when assembling the bipolar plate from two bipolar plate layers, or when assembling different components of the sealing assembly or the membrane electrode assembly.

[0043] Preferably, the support elements of the connection channels of the electrochemical unit are only configured on one side, i.e., only on one of the two bipolar plate layers of the bipolar plate, and the support elements are configured, for example, as recesses in one of the bipolar plate layers of the bipolar plate.

[0044] Since there are no structures critical for the sealing between the secondary side of the bipolar plate and the secondary side of the sealing assembly or membrane electrode assembly (e.g., support elements, ramps, ribs or the like), a relatively large offset between the secondary members forming the secondary side of the bipolar plate or the sealing assembly or membrane electrode assembly can be allowed relative to each other. Thus, the assembly offsets occurring during the assembly of the secondary side of the bipolar plate and the secondary side of the sealing assembly or membrane electrode assembly can be compensated for and / or tolerated.

[0045] In an electrochemical device of a type known from the prior art, the flow ports or connection channels are open in two directions relative to the reference level of the respective bipolar plate, wherein ramps are constructed on both sides of the bipolar plate or on two bipolar plate layers of the bipolar plate, and the sealing line extends along the ramps from the reference level or the block level to the flow ports or connection channels.

[0046] These ramps represent features critical for the sealing between the bipolar plate and the sealing assembly, which require precise positioning relative to other seal-related structures. Therefore, these structures critical for sealing are arranged on the primary side of the bipolar plate and the primary side of the sealing assembly or membrane electrode assembly.

[0047] In contrast, the secondary side of the bipolar plate preferably has no structures critical for sealing, in particular no support elements for the connection channels and / or no ramps, while the primary side of the bipolar plate has such structures critical for sealing, in particular support elements for the connection channels and / or ramps.

[0048] Thus, the planar secondary side of the bipolar plate in the sealing region adjacent to the sealing assembly allows for a greater offset tolerance and thus matches the secondary member of the bipolar plate.

[0049] Further design adjustments can be made when designing the primary and secondary sides of the bipolar plate and / or when designing the primary or secondary side of the sealing assembly.

[0050] For example, the elastomeric sealing element of the sealing assembly can be injection-molded onto the adjacent bipolar plate, wherein the sealing assembly includes a separately embedded seal as a second elastomeric sealing element, which has a greater offset tolerance and cooperates with the seal-related structures of another bipolar plate stacked subsequently.

[0051] The sealing assembly can be implemented substantially flat on its secondary side in the sealing region where the sealing assembly is in fluid-sealed contact with the bipolar plate, such that only on the opposite primary side of the sealing assembly, i.e., on the side where one or more sealing lips are arranged, there are higher tolerance requirements for the assembly of the stack composed of electrochemical cells.

[0052] Support elements, which keep the first boundary wall of the connection channels of the electrochemical unit at a distance from the second boundary wall of the connection channels in the stacking direction, are preferably only constructed on one bipolar plate layer of the bipolar plate. These support elements contact the other bipolar plate layer of the bipolar plate and thus ensure that the first boundary wall of the connection channels is supported on the second boundary wall of the connection channels.

[0053] The bottom of the depression of the support element constructed as a depression abuts against the as-flat-as-possible contact surface in the contact area of the other bipolar plate layer without the support element and can be designed to be narrower because there is no need to precisely fit the corresponding surface to this support element.

[0054] Preferably, all sealing-related structures of the connection channels of the electrochemical device, in particular support elements constructed as depressions and inclined surfaces or ramps raised towards one of the boundary walls of the connection channels, are arranged only on one of the bipolar plate layers of the bipolar plate.

[0055] The positioning of the sealing assembly relative to the inclined surface or ramp of the connection channel of the bipolar plate represents higher tolerance requirements during the assembly of the stack composed of electrochemical units.

[0056] Due to the asymmetric distribution of the sealing-related structures, i.e., these structures are only arranged on one of the two bipolar plate layers of the bipolar plate, the bulge height in the area of the connection channel at the bipolar plate layer provided with the sealing-related structures is greater compared to the construction of the connection channels in the prior art. The increased forming difficulty due to the higher bulge at this bipolar plate layer is offset by the following advantage, from which it follows that the support element constructed as a depression does not protrude beyond the substantially flat boundary wall of the connection channel formed by the second bipolar plate layer.

[0057] In a preferred design of the present invention, it is provided that at least one main structure is arranged on the main side of each bipolar plate and at least one main structure is arranged on the main side of each sealing assembly, wherein the encounter of the main structure of the bipolar plate and the main structure of the sealing assembly results in unsealing, and wherein the target spacing in the transverse direction between the main structure of the bipolar plate and the main structure of the sealing assembly is greater than the first offset tolerance.

[0058] Here, the target spacing in the transverse direction between the main structure of the bipolar plate and the main structure of the sealing assembly is preferably less than the second offset tolerance.

[0059] Preferably, it can also be provided that no auxiliary structures are arranged on the auxiliary side of the bipolar plate, which would cause unsealing when encountering the auxiliary structures on the auxiliary side of the sealing assembly.

[0060] In a preferred design of the present invention, the bipolar plate is constructed to be substantially flat or flat at least in the sealing area opposite to the auxiliary side of the sealing assembly on the auxiliary side.

[0061] If the bipolar plates each comprise at least a first bipolar plate layer and a second bipolar plate layer, preferably, the main side of each bipolar plate is configured on the first bipolar plate layer, and the secondary side of each bipolar plate is configured on the second bipolar plate layer.

[0062] It can be provided here that the first bipolar plate layer and the second bipolar plate layer of each bipolar plate are connected to each other in a material-locking manner, for example by welding, in particular by laser welding.

[0063] Preferably, the electrochemical device comprises at least one medium channel through which a fluid medium can be fed into or discharged from the electrochemical unit of the electrochemical device.

[0064] Such a fluid medium can be, for example, the anode gas (fuel gas), the cathode gas (oxidant) or the coolant of the electrochemical device.

[0065] If the bipolar plates each have at least one flow field for such a fluid medium, it is advantageous that each electrochemical unit comprises a connection channel through which the flow field of the respective bipolar plate is in fluid connection with the assigned medium channel, which medium channel is flowed through by the same fluid medium as the fluid medium flowing through the flow field during operation of the electrochemical device.

[0066] It can be provided here that the bipolar plates each have at least one support element configured as a depression on the main side for the connection channel.

[0067] Furthermore, it can be provided that the sealing assembly each has at least one sealing lip on the secondary side.

[0068] The target spacing between the respective support elements of the bipolar plates and the sealing lips on the secondary side of the sealing assembly is preferably greater than the first offset tolerance and / or preferably less than the second offset tolerance.

[0069] Particularly advantageously, the bipolar plates have no structure of connection channels on the secondary side, in particular neither support elements of connection channels nor inclined surfaces or ramps of connection channels.

[0070] The main side of the bipolar plates can be connected to the main side of the sealing assembly in a material-locking manner. Through this material-locking connection, a particularly precise and durable positioning of the main side of the bipolar plates relative to the main side of the sealing assembly is achieved.

[0071] In a specific design of the present invention, it is provided that the secondary side of the sealing assembly does not have a sealing lip.

[0072] The present invention also relates to an electrochemical device comprising a plurality of electrochemical units following one another in a stacking direction, wherein each electrochemical unit comprises a bipolar plate and a sealing assembly.

[0073] Another object of the present invention is to create an electrochemical device in which, even if the sealing assembly has an offset in the lateral direction oriented perpendicular to the stacking direction of the electrochemical unit due to component tolerances and / or assembly tolerances, a reliable fluid-tight seal between the bipolar plates of the stack formed by the electrochemical units and the sealing assembly can be ensured.

[0074] Preferably, the lateral direction is also perpendicular to the circumferential direction of the sealing assembly or the circumferential direction of the edge tabs of the flow field of the bipolar plate.

[0075] According to the present invention, this object is solved by an electrochemical device according to claim 15, wherein each bipolar plate has a main side and a secondary side facing away from the main side, wherein each sealing assembly has a main side and a secondary side facing away from the main side, wherein the main side of each sealing assembly is in contact with the main side of the adjacent first bipolar plate, wherein the first offset tolerance is defined by the maximum offset between the main side of the sealing assembly and the main side of the adjacent first bipolar plate in the stack formed by the electrochemical units of the electrochemical device, wherein the secondary side of each sealing assembly is in contact with the secondary side of the adjacent second bipolar plate, wherein the second offset tolerance is defined by the maximum offset between the secondary side of the sealing assembly and the secondary side of the adjacent second bipolar plate in the stack formed by the electrochemical units of the electrochemical device, and wherein the first offset tolerance is less than the second offset tolerance.

[0076] The specific design of the electrochemical device according to the present invention has been described above in connection with a specific design of the method for assembling a stack formed by the electrochemical units of the electrochemical device according to the present invention.

[0077] The main sides of the bipolar plates and the sealing assembly are characterized in that the main sides can be measured and / or positioned more precisely than the secondary sides.

[0078] The method for assembling a stack formed by the electrochemical units of the electrochemical device according to the present invention is particularly suitable for manufacturing the electrochemical device according to the present invention.

[0079] The electrochemical device according to the present invention is preferably manufactured according to the method for assembling a stack formed by the electrochemical units of the electrochemical device according to the present invention.

[0080] The electrochemical device according to the present invention is preferably configured as a polymer electrolyte membrane (PEM) fuel cell device. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Other features and advantages of the present invention will be clarified below in conjunction with the description of the drawings and specific embodiments.

[0082] In the drawings:

[0083] Figure 1 Shows a cross-section of an edge region of an electrochemical cell of an electrochemical device including a plurality of electrochemical cells following one another in a stacking direction and a bipolar plate of an adjacent electrochemical cell, wherein the electrochemical cell includes a membrane electrode assembly, a bipolar plate having a flow field for a fluid medium formed thereon, and a sealing assembly, wherein the sealing assembly includes two elastomeric sealing elements, wherein the electrochemical device includes at least one medium channel and at least one connection channel, the medium channel can be traversed by a fluid medium and extends parallel to the stacking direction, and in the normal state of the electrochemical device, the medium channel is in fluid connection with the flow field of the bipolar plate through the connection channel, wherein a sealing lip of one of the elastomeric sealing elements of the sealing assembly is sealingly and tightly abutted against a first boundary wall of the fluid channel;

[0084] Figure 2 Shows the same as Figure 1 A cross-section of an edge region of an electrochemical cell of a corresponding electrochemical device and a bipolar plate of an adjacent electrochemical cell, wherein the sealing assembly of the electrochemical cell is displaced relative to the bipolar plate in a transverse direction perpendicular to the stacking direction, such that a sealing lip of one of the elastomeric sealing elements of the sealing assembly reaches into a region of a support element, the support element being configured as a depression in a first bipolar plate layer of the bipolar plate of the electrochemical cell, such that the sealing lip no longer contacts the first boundary wall of the fluid channel and thus no longer functions as a seal; and

[0085] Figure 3 Shows the same as Figure 1 A cross-section of an edge region of an electrochemical cell of a corresponding electrochemical device according to the present invention and a bipolar plate of an adjacent electrochemical cell, wherein each bipolar plate of the electrochemical cell of the electrochemical device has a main side and a secondary side facing away from the main side, wherein each sealing assembly has a main side and a secondary side facing away from the main side, wherein the main side of each sealing assembly contacts the main side of an adjacent first bipolar plate, and a first offset tolerance is defined by a maximum offset between the main side of the sealing assembly and the main side of the adjacent first bipolar plate of the relevant sealing assembly, wherein the secondary side of each sealing assembly contacts the secondary side of an adjacent second bipolar plate, and a second offset tolerance is defined by a maximum offset between the secondary side of the sealing assembly and the secondary side of the adjacent second bipolar plate of the relevant sealing assembly, and wherein the first offset tolerance is less than the second offset tolerance.

[0086] Elements that are the same or functionally equivalent in the respective figures are labeled with the same reference numerals. Detailed Description

[0087] Figure 1 And Figure 2 The electrochemical device 100 shown in and includes a plurality of electrochemical cells 102, 102' following one another in the stacking direction 104 of the electrochemical device 100.

[0088] Each electrochemical cell 102 includes a membrane electrode assembly (MEA) 106, a first gas diffusion layer 108, a second gas diffusion layer 110, a sealing assembly 112, and a bipolar plate 114.

[0089] In this embodiment, the sealing assembly 112 includes a first elastomeric sealing element 116 that is preferably connected to the first gas diffusion layer 108 by material locking, and a second elastomeric sealing element 118 that is (preferably by material locking) connected to the second gas diffusion layer 110.

[0090] The bipolar plate 114 includes a first bipolar plate layer 120 and a second bipolar plate layer 126. The first elastomeric sealing element 116 of the sealing assembly 112 abuts against the first bipolar plate layer 120 with two sealing lips 122 and two sealing lips 124. The first elastomeric sealing element 116 of the sealing assembly 112 of the adjacent electrochemical cell 102' abuts against the second bipolar plate layer 126 with two sealing lips 128, and the second elastomeric sealing element 118 of the sealing assembly 112 of the adjacent electrochemical cell 102 abuts against the second bipolar plate layer 126 with two sealing lips 130.

[0091] Each of the bipolar plate layers 120, 126 includes a flow field 132 in its central region. In Figure 1 and Figure 2 only the edge tabs 134 that define the respective flow fields 132 towards the outside are shown.

[0092] For example, it can be arranged that the first bipolar plate layer 120 includes an anode gas flow field 136, and the second bipolar plate layer 126 includes a cathode gas flow field 138.

[0093] A coolant flow field (not shown) can also be constructed between the two bipolar plate layers 120 and 126 of the bipolar plate 114.

[0094] The electrochemical device 100 further includes a plurality of medium channels 140 that extend parallel to the stacking direction 104, and through these medium channels, fluid media required for operating the electrochemical device 100, such as anode gas (fuel gas), cathode gas (oxidant), and coolant, can be supplied to the electrochemical cells 102.

[0095] In Figure 1 and Figure 2 one of these medium channels 140 is located on the right side of the outer edge 142 of the sealing assembly 112.

[0096] Each medium channel 140 that can supply fluid medium to the electrochemical device 100 or discharge fluid medium from the electrochemical device 100 is in fluid connection with the associated flow field 132 for the relevant fluid medium through a connection channel 144.

[0097] Figure 1 and Figure 2 Exemplarily shown in FIGS. 2 and 3 are two connecting channels 144 through which anode gas can be respectively delivered from the medium channel 140 to the anode gas flow field 136 in a direction perpendicular to the stacking direction 104 as indicated by arrow 146.

[0098] Each fluid channel includes a first boundary wall 148 and a second boundary wall 150 that define a flow path for the respective fluid medium through the connecting channel 144.

[0099] Furthermore, each connecting channel 144 includes one or more support elements 152 through which the first boundary wall 148 and the second boundary wall 150 of the connecting channel 144 are held spaced apart from each other along the stacking direction 104 of the electrochemical device 100.

[0100] In Figure 1 and Figure 2 In the embodiment shown in FIGS. 2 and 3, the support element 152 is configured as a recess 154 formed in the first bipolar plate layer 120, and the region of the first bipolar plate layer 120 between the recesses 154 forms the first boundary wall 148 of the connecting channel 144.

[0101] Each support element 152 formed at the first bipolar plate layer 120 is respectively associated with a support element 152' configured as a recess 154' in the second bipolar plate layer 126, and the region of the second bipolar plate layer 126 between the recesses 154' forms the second boundary wall 150 of the connecting channel 144.

[0102] The bottoms of the recesses 154 in the first bipolar plate layer 120 respectively abut against the bottoms of the associated recesses 154' in the second bipolar plate layer 126, so that the first boundary wall 148 of the connecting channel 144 is supported on the second boundary wall 150 of the connecting channel 144 by the support elements 152 and 152'.

[0103] Preferably, the second bipolar plate layer 126 is configured to be substantially mirror-symmetrical with the first bipolar plate layer 120 in the region of the connecting channel 144.

[0104] The sealing assembly 112 includes a flow field sealing region 156 that extends around the flow fields 132 of the bipolar plate layers 120 and 126 adjacent to the sealing assembly 112 and seals them with respect to the surrounding environment of the electrochemical device 100 and the medium channel 140.

[0105] The flow field enclosed region 156 includes a sealing line, and the sealing lips 122 of the first elastomeric sealing element 116 and the sealing lips 130 of the second elastomeric sealing element 118 are hermetically abutted against the adjacent bipolar plate layers 120 and 126 respectively along these sealing lines.

[0106] In addition, the sealing assembly 112 includes a plurality of medium channel enclosed regions 158, as Figure 1 and Figure 2 shown. These medium channel enclosed regions 158 respectively extend around one of the medium channels 140 of the electrochemical device 100 and seal the relevant medium channel 140 with respect to the surrounding environment of the electrochemical device, the flow field 132, and other medium channels 140.

[0107] In Figure 1 and Figure 2 the embodiment of the sealing assembly 112 shown, the medium channel enclosed region 158 includes a sealing line along which the sealing lip 124 of the first elastomeric sealing element 116 abuts against the adjacent first bipolar plate layer 120 and a sealing line along which the sealing lip 128 of the first elastomeric sealing element 116 hermetically abuts against the adjacent second bipolar plate layer 126.

[0108] As can be seen from Figure 1 the sealing lips 122 and 124 of the first elastomeric sealing element 116 of the sealing assembly 112 hermetically abut against the first bipolar plate layer 120 in the region between the support elements 152 of the adjacent first bipolar plate layer 120.

[0109] However, due to component tolerances caused by manufacturing and / or assembly tolerances caused by the assembly process of the electrochemical device 100, the sealing assembly 112 and the adjacent bipolar plate layers 120 and 126 may shift in the lateral direction 162 perpendicular to the stacking direction 104 of the electrochemical device 100 and perpendicular to the circumferential direction 160 of the sealing assembly 112. Among them, the shift may be large enough to cause one of the sealing lips 122 of the flow field enclosed region 156 of the sealing assembly 112 and / or one of the sealing lips 124 of the medium channel enclosed region 158 of the sealing assembly 112 to reach the region of one of the support elements 152 configured as the recess 154 and no longer contact the first boundary wall 148 of the connection channel 144.

[0110] Due to this shift between the sealing assembly 112 and the adjacent bipolar plate layers 120, 126, fluid sealing can no longer be guaranteed at the relevant sealing lips 122 and 124.

[0111] Due to the offset of the sealing assembly 112 and the bipolar plate layers 120 and 126 adjacent to the sealing assembly 112 in the transverse direction 162, one of the sealing lips 128 of the first elastomeric sealing element 116 that abuts against the second bipolar plate layer 126 of the bipolar plate 114' of the adjacent electrochemical cell 102' and / or one of the sealing lips 130 of the second elastomeric sealing element 118 that abuts against the second bipolar plate layer 126 of the bipolar plate 114' of the adjacent electrochemical cell 102' may reach the area of the support element 152' configured as a recess 154' in the second bipolar plate layer 126 and no longer contact the second boundary wall 150 of the connection channel 144' of the adjacent electrochemical cell 102'.

[0112] Due to this offset between the sealing assembly 112 and the adjacent bipolar plate layers 120, 126, a fluid-tight seal cannot be guaranteed at the relevant sealing lips 128 and 130 anymore.

[0113] In order to prevent the sealing lips of the sealing assembly 112 from reaching the area of the support element 152 configured as a recess 154 in the connection channel 144 and / or the area of the support element 152' configured as a recess 154' in the connection channel 144' due to component tolerances and / or assembly tolerances, the spacing between the sealing lips 122, 124, 128, 130 of the sealing assembly 112 and the support elements 152, 152' of the connection channels 144, 144' must be increased.

[0114] However, increasing this spacing will also cause the spacing between the support elements 152, 152' of the connection channels 144, 144' to increase, which causes the bipolar plates 114 and 114' to be overly deflected due to the pressure transmitted through the sealing lips 122, 124, 128, 130.

[0115] This excessive deflection of the bipolar plates 114 and 114' will further cause the sealing force of the sealing lips 122, 124, 128, 130 of the sealing assembly 112 to decrease, and this excessive deflection will cause the flow-through cross-section of the connection channels 144 and 144' to shrink.

[0116] The decrease in the sealing force of the sealing assembly 112 poses a risk of unsealing at high operating pressures of the electrochemical device 100.

[0117] In order to solve the problem of unsealing caused by the offset between the sealing assembly 112 and the adjacent bipolar plate layers 120, 126 without increasing the spacing between the sealing lips 122, 124, 128 and 130 and the support elements 152, 152' of the connection channels 144, 144', the present invention provides Figure 3 the illustrated embodiment of the electrochemical device 100 according to the present invention.

[0118] In the present embodiment of the electrochemical device 100, the support element 152 in the form of the recess 154 is only constructed on the first bipolar plate layer 120, while the second bipolar plate layer 126 of each bipolar plate 114 or 114' is configured to be substantially flat in the region of the connection channels 144 or 144'.

[0119] The regions of the first bipolar plate layer 120 between the recesses 154 respectively form the first boundary walls 148 of the connection channels 144 or 144', while the substantially flat regions of the second bipolar plate layer 126 in the regions of the connection channels 144 or 144' respectively form the second boundary walls 150 of the associated connection channels 144 or 144'.

[0120] In Figure 3 the illustrated embodiment of the electrochemical device 100, since the bulges of the connection channels 144 and 144' between the support elements 152 are only constructed on the first bipolar plate layer 120 and the bulge height is the same as Figure 1 the bulge height in the illustrated first embodiment, therefore, compared with Figure 1 the illustrated embodiment, Figure 3 the flow-through cross-sections of the connection channels 144 and 144' in the illustrated embodiment are smaller. This can be compensated by Figure 3 increasing the bulge height between the support elements 152 (i.e., increasing the extension in the stacking direction 104) in the illustrated embodiment.

[0121] The side of each bipolar plate 114, 114' on which the first bipolar plate layer 120 (which is provided with the support element 152 configured as the recess 154) is respectively arranged forms the main side 200 of the respective bipolar plates 114, 114'.

[0122] The first bipolar plate layer 120 thus forms the main component 212 of the bipolar plate 114 or 114'.

[0123] The side of the bipolar plates 114, 114' that faces away from the main side 200 of the bipolar plates 114, 114' forms the secondary side 202 of the bipolar plates 114, 114', on which the respective second bipolar plate layers 126 are arranged, and the second bipolar plate layer is configured to be substantially flat in the regions of the connection channels 144, 144'.

[0124] The second bipolar plate layer 126 thus forms the secondary component 214 of the bipolar plate 114 or 114'.

[0125] The side of each sealing assembly 112 that is in contact with the main side 200 of the adjacent first bipolar plate 114 forms the main side 204 of the sealing assembly 112, on which the sealing lips 122 and 124 of the first elastomeric sealing element 116 are arranged.

[0126] The first elastomeric sealing element 116 thus forms the main member 216 of the sealing assembly 112.

[0127] On each side of each sealing assembly 112 that faces away from the main side 204 of the sealing assembly 112, a secondary side 206 of the respective sealing assembly 112 is formed. This side is in contact with the secondary side 202 of the adjacent second bipolar plate 114', and on this side, a sealing lip 128 of the first elastomeric sealing element 116 and a sealing lip 130 of the second elastomeric sealing element 118 are arranged.

[0128] The second elastomeric sealing element 118 thus forms the secondary member 218 of the sealing assembly 112.

[0129] The first offset tolerance is defined by the maximum offset that occurs in the stack formed by the electrochemical cells 102 of the electrochemical device 100, between the main side 204 of the sealing assembly 112 and the main side 200 of the respective adjacent first bipolar plate 114 of the sealing assembly 112.

[0130] The second offset tolerance is defined by the maximum offset that occurs in the stack formed by the electrochemical cells 102 of the electrochemical device 100, between the secondary side 206 of the sealing assembly 112 and the secondary side 202 of the respective adjacent second bipolar plate 114' of the sealing assembly 112.

[0131] Since during the assembly of the stack formed by the electrochemical cells 102, the main side 204 of the sealing assembly 112 is positioned extremely precisely relative to the main side 200 of the respective adjacent first bipolar plate 114, while a greater offset is tolerated when positioning the secondary side 206 of the sealing assembly 112 with respect to the secondary side 202 of the respective adjacent second bipolar plate 114' of the sealing assembly 112, the first offset tolerance is less than the second offset tolerance.

[0132] Preferably, the first offset tolerance is less than 50%, especially 20%, and particularly preferably 10% of the second offset tolerance.

[0133] Thereby, it can be ensured that the offset between the main side of the sealing assembly 112 and the main side 200 of the bipolar plate 114 in contact with it respectively in all the electrochemical cells 102 of the stack formed by the electrochemical cells 102 of the electrochemical device 100 is very small, so that the sealing lips 122, 124 on the main side 204 of the sealing assembly 112 do not reach the area of the support element 152 configured as the recess 154, and thus do not disengage from the first boundary wall 148 of the respective adjacent connection channel 144. Therefore, the main side 204 of the sealing assembly 112 and the main side 200 of the bipolar plate 114 are free from unsealing.

[0134] Although the offset in the transverse direction 162 between the secondary side 206 of the sealing assembly 112 and the secondary side 202 of the bipolar plate 114' is significantly larger, this does not prevent the sealing function of the sealing assembly 112 because the sealing lips 128, 130 on the secondary side 206 of the sealing assembly 112 contact the substantially flat secondary side 202 of the bipolar plate 114', so that the sealing lips 128, 130 never reach the area of the support element 152 configured as the depression 154 from beginning to end and thus do not disengage from the second boundary wall 150 of the respectively adjacent connection channel 144'.

[0135] Although there may be a large offset between the secondary side 206 of the sealing assembly 112 and the secondary side 202 of the bipolar plate 114', reliable sealing between the secondary side 206 of the sealing assembly 112 and the secondary side 202 of the bipolar plate 114' in each electrochemical cell 102 of the stack formed by the electrochemical cells 102 of the electrochemical device 100 can still be ensured.

[0136] To assemble a stack formed by the electrochemical cells 102 of the electrochemical device 100, the following steps are taken:

[0137] Provide bipolar plates 114, 114' which respectively have a primary side 200 and a secondary side 202 facing away from the primary side 200.

[0138] Provide a sealing assembly 112 which respectively has a primary side 204 and a secondary side 206 facing away from the primary side 204.

[0139] Bring the primary side 204 of the sealing assembly 112 and the primary side 200 of the adjacent first bipolar plate 114 into contact with each other, wherein the primary side 204 of the sealing assembly 112 and the primary side 200 of the adjacent first bipolar plate 114 are positioned relative to each other to follow a first offset tolerance in the transverse direction 162 which is perpendicular to the stacking direction 104 of the electrochemical device.

[0140] Bring the secondary side 206 of the sealing assembly 112 and the secondary side 202 of the adjacent second bipolar plate 114' into contact with each other, wherein the secondary side 206 of the sealing assembly 112 and the secondary side 202 of the adjacent second bipolar plate 114' are positioned relative to each other to follow a second offset tolerance in the transverse direction 162.

[0141] Repeat the above steps of bringing the primary side 204 of the sealing assembly 112 into contact with the primary side 200 of the adjacent first bipolar plate 114 and the steps of bringing the secondary side 206 of the sealing assembly 112 into contact with the secondary side 202 of the adjacent second bipolar plate 114' until all the sealing assemblies 112 are in contact with the bipolar plates 114, 114' to be contacted.

[0142] The first offset tolerance between the main side 204 of the sealing assembly 112 and the main side 200 of the adjacent first bipolar plate 114 in contact therewith respectively is less than the second offset tolerance between the secondary side 206 of the sealing assembly 112 and the secondary side 202 of the adjacent second bipolar plate 114' in contact therewith respectively.

[0143] Preferably, the first offset tolerance is less than 50%, especially 20%, and particularly preferably 10% of the second offset tolerance.

[0144] On the main side 200 of each bipolar plate 114, a support element 152 configured as a depression 154 is arranged as the main structure 208.

[0145] On the main side 204 of each sealing assembly 112, the sealing lips 122 and 124 of the sealing assembly 112 are arranged as the main structure 210.

[0146] The encounter between the main structure 208 of the bipolar plate 114 and the main structure 210 of the adjacent sealing assembly 112 may cause unsealing between the sealing assembly 112 and the bipolar plate 114, but this can be avoided by making the target spacing in the lateral direction 162 between each main structure 208 of the bipolar plate 114 and each main structure 210 of the adjacent sealing assembly 112 greater than the first offset tolerance followed during the assembly of the stack formed by the electrochemical cells 102 of the electrochemical device 100.

[0147] Preferably, this target spacing between the main structure 208 of the bipolar plate 114 and the main structure 210 of the adjacent sealing assembly 112 is less than the second offset tolerance.

[0148] On the secondary side 202 of each bipolar plate 114', no secondary structures are arranged, and the encounter between these secondary structures and the secondary structures on the secondary side 206 of the respectively adjacent sealing assembly 112 may cause unsealing of the sealing assembly 112.

[0149] Preferably, the first bipolar plate layer 120 and the second bipolar plate layer 126 of each of the bipolar plates 114, 114' are connected to each other by material locking, for example, by welding, and particularly preferably by laser welding.

[0150] Preferably, the target spacing between each support element 152 configured as a depression 154 of the bipolar plate 114 and each of the sealing lips 122, 124 of the respectively adjacent sealing assembly 112 is greater than the first offset tolerance and / or less than the second offset tolerance, which is followed during the assembly of the stack of the electrochemical cells 102 of the electrochemical device 100.

Claims

1. A method for assembling a stack composed of electrochemical cells (102) of an electrochemical device (100), wherein, The electrochemical cells (102) follow one another in a stacking direction (104), and wherein each electrochemical cell (102) comprises a bipolar plate (114; 114') and a sealing assembly (112), the method comprising the following steps: a) providing bipolar plates (114; 114'), each bipolar plate having a main side (200) and a secondary side (202) facing away from the main side (200); b) providing a sealing assembly (112), each sealing assembly having a main side (204) and a secondary side (206) facing away from the main side (204); c) bringing the main side (204) of the sealing assembly (112) into contact with the main side (200) of an adjacent first bipolar plate (114), wherein the main side (204) of the sealing assembly (112) and the main side (200) of the adjacent first bipolar plate (114) are positioned relative to one another to follow a first offset tolerance in a lateral direction (162) oriented perpendicular to the stacking direction (104); d) bringing the secondary side (206) of the sealing assembly (112) into contact with the secondary side (202) of an adjacent second bipolar plate (114'), wherein the secondary side (206) of the sealing assembly (112) and the secondary side (202) of the adjacent second bipolar plate (114') are positioned relative to one another to follow a second offset tolerance in the lateral direction (162); - repeating steps c) and d) until all the sealing assemblies (112) are in contact with the bipolar plates (114; 114') to be contacted respectively; wherein the first offset tolerance is less than the second offset tolerance.

2. The method according to claim 1, characterized in that, At least one main structure (208) is arranged on the main side (200) of each bipolar plate (114), and at least one main structure (210) is arranged on the main side (204) of each sealing assembly (112), wherein the meeting of the main structure (208) of the bipolar plate (114) and the main structure (210) of the sealing assembly (112) results in unsealing, and wherein the target spacing between the main structure (208) of the bipolar plate (114) and the main structure (210) of the sealing assembly (112) in the lateral direction (162) is greater than the first offset tolerance.

3. The method according to claim 2, wherein The target spacing between the main structure (208) of the bipolar plate (114) and the main structure (210) of the sealing assembly (112) in the lateral direction (162) is less than the second offset tolerance.

4. The method according to any one of claims 1 to 3, characterized in that No secondary structure is arranged on the secondary side (202) of the bipolar plates (114; 114') that causes unsealing when meeting the secondary structure of the secondary side (206) of the sealing assembly (112).

5. The method according to any one of claims 1 to 4, characterized in that, The bipolar plates (114; 114') are configured to be substantially flat on the secondary side (202) at least in the closed area facing the secondary side (206) of the sealing assembly (112).

6. The method according to any one of claims 1 to 5, characterized in that The bipolar plates (114; 114') each include at least a first bipolar plate layer (120) and a second bipolar plate layer (126), wherein the main side (200) of each bipolar plate (114; 114') is constructed on the first bipolar plate layer (120), and the secondary side (202) of each bipolar plate (114; 114') is constructed on the second bipolar plate layer (126).

7. The method according to claim 6, wherein The first bipolar plate layer (120) and the second bipolar plate layer (126) of each bipolar plate (114; 114') are connected to each other in a material-locking manner.

8. The method according to any one of claims 1 to 7, characterized in that, The electrochemical device (100) includes at least one medium channel (140) through which a fluid medium can be fed into or discharged from the electrochemical unit (102) of the electrochemical device (100), wherein the bipolar plates (114; 114') each have at least one flow field (132) for such a fluid medium, and each electrochemical unit (102) includes a connection channel (144), and the flow field (132) is in fluid connection with the assigned medium channel (140) through the connection channel.

9. The method according to claim 8, wherein The bipolar plates (114; 114') each have at least one support element (152) configured as a depression (154) for the connection channel (144) on the main side (200).

10. The method according to claim 9, wherein The sealing assembly (112) each has at least one sealing lip (128, 130) on the secondary side (206).

11. The method according to claim 10, wherein The target spacing between each support element (152) of the bipolar plates (114; 114') and the sealing lips (128, 130) on the secondary side (206) of the sealing assembly (112) is greater than the first offset tolerance and less than the second offset tolerance.

12. The method according to any one of claims 8 to 11, characterized in that, The bipolar plates (114; 114') do not have the structure of the connection channel (144; 144') on the secondary side (202).

13. The method according to any one of claims 1 to 12, characterized in that, The main sides (200) of the bipolar plates (114; 114') are each connected to the main side (204) of the sealing assembly (112) in a material-locking manner.

14. The method according to any one of claims 1 to 13, characterized in that, The secondary side (206) of the sealing assembly (112) does not have a sealing lip.

15. An electrochemical device, the electrochemical device comprising a plurality of electrochemical cells (102) following one another in a stacking direction (104), wherein, Each electrochemical unit (102) includes a bipolar plate (114; 114') and a sealing assembly (112), wherein each bipolar plate (114; 114') has a main side (200) and a secondary side (202) facing away from the main side (200), wherein each sealing assembly (112) has a main side (204) and a secondary side (206) facing away from the main side (204), wherein the main side (204) of each sealing assembly (112) is in contact with the main side (200) of the adjacent first bipolar plate (114), and the first offset tolerance is defined by the maximum offset between the main side (204) of the sealing assembly (112) and the main side (200) of the adjacent first bipolar plate (114) of the associated sealing assembly (112) in the stack formed by the electrochemical units (102) of the electrochemical device (100). Wherein, the secondary side (206) of each sealing assembly (112) is in contact with the secondary side (202) of an adjacent second bipolar plate (114'), and the second offset tolerance is defined by a maximum offset between the secondary side (206) of the sealing assembly (112) in a stack formed by the electrochemical cells (102) of the electrochemical device (100) and the secondary side (202) of an adjacent second bipolar plate (114') of the associated sealing assembly (112), and wherein, the first offset tolerance is less than the second offset tolerance.

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