Bipolar plate and electrochemical device comprising bipolar plate

Abstract

In order to provide a bipolar plate for an electrochemical cell of an electrochemical device comprising a plurality of electrochemical cells, the bipolar plate comprises an anode gas flow field, a cathode gas flow field and a coolant flow field, the anode gas flow field comprises an anode gas flow channel through which an anode gas can flow, and the coolant flow field comprises a coolant flow channel through which a coolant gas can flow. The cathode gas flow field comprises a cathode gas flow channel through which a cathode gas can flow, and the coolant flow field comprises a coolant flow channel through which a coolant can flow, in which the bipolar plate layers can be integrally connected to one another without compromising the cooling function of the bipolar plate, according to the invention, the at least one anode gas flow channel and / or the at least one cathode gas flow channel is widened locally in such a way that at least one adjacent section of the coolant flow channel is moved locally in the transverse direction of the anode gas flow channel or the cathode gas flow channel, a section of the other anode gas flow channel or the other cathode gas flow channel, which is adjacent to the section of the coolant flow channel that is partially displaced, is partially narrowed down, and wherein the anode-side bipolar plate layer and the cathode-side bipolar plate layer are integrally bonded to each other within the respective partially widened region at at least one connection region.

Description

Technical Field

[0001] The present invention relates to a bipolar plate for an electrochemical cell of an electrochemical device, wherein the electrochemical device comprises a plurality of electrochemical cells, which follow one another in a stacking direction, wherein the bipolar plate comprises:

[0002] - an electrochemically active area, comprising an anode gas flow field through which anode gas can flow transversely to the stacking direction, a cathode gas flow field through which cathode gas can flow transversely to the stacking direction, and a coolant flow field through which coolant can flow transversely to the stacking direction,

[0003] The anode gas flow field includes an anode gas flow channel through which the anode gas can flow, the cathode gas flow field includes a cathode gas flow channel through which the cathode gas can flow, and the coolant flow field includes a coolant flow channel through which the coolant can flow.

[0004] The anode gas flow field is constructed on the bipolar plate layer on the anode side, and the cathode gas flow field is constructed on the bipolar plate layer on the cathode side. Background Art

[0005] These bipolar plate layers are preferably formed of a metallic material and are connected to each other in a gas-tight manner by a joining process, typically a laser welding process.

[0006] These bipolar plate layers must distribute the anode gas and cathode gas as evenly as possible over the electrochemically active area of ​​the bipolar plates and must conduct a coolant between them for cooling the electrochemically active area of ​​the electrochemical device.

[0007] Furthermore, these bipolar plate layers must have very good electrical conductivity in order to ensure proper electrical function of the electrochemical device.

[0008] For example, the bipolar plate layers on the anode side and / or the bipolar plate layers on the cathode side can be formed from austenitic stainless steel, preferably from steel with material number 1.4404.

[0009] The specific resistivity of steel with material number 1.4404 is approximately 0.75 Ω·mm 2 / m.

[0010] This steel has a natural passive layer (chromium oxide layer) on its surface, which has a low electrical conductivity. Therefore, it is necessary to provide the bipolar plates with an electrically conductive coating on the outer sides of the bipolar plate layers that each face the electrodes of the membrane electrode unit.

[0011] If the inner sides of the bipolar plate layers facing one another are not provided with such an electrically conductive coating, these inner sides of the bipolar plate layers must be materially bonded to one another in order to ensure the required electrical conductivity between the bipolar plate layers of the bipolar plate.

[0012] Such a cohesive connection can be produced, for example, by a weld seam, wherein the weld seam is interrupted and can comprise weld seam sections (jump welds) or weld points (weld spots) separated from one another.

[0013] Such a welded connection can be produced in particular by laser welding.

[0014] In order to weld such an electrically conductive seam, the area in which the bipolar plate layers on the anode side and the bipolar plate layers on the cathode side can be placed against each other and welded to each other, that is, the channel bottom of the anode gas flow channel and / or the channel bottom of the cathode gas flow channel on which the welding is to be performed, must have a minimum width due to the accumulation of manufacturing tolerances, which are caused, for example, by tolerances in the width of the weld seam, tolerances in the positioning of the weld seam relative to the bipolar plate layers, and tolerances in the relative positioning of the bipolar plate layers with respect to each other.

[0015] The minimum channel width is, for example, in the range of at least 0.2 mm.

[0016] However, recent developments in the field of bipolar plate technology are trending towards increasingly narrow channel structures in order to improve the gas distribution dynamics and to ensure adequate support for adjacent components, in particular the membrane electrode assembly.

[0017] However, narrower anode gas flow channels or cathode gas flow channels reduce the weldability of the bipolar plate layers in the flow field or at least reduce the process capability, which may result in more scrap in larger batch production.

[0018] In the bipolar plate according to EP 2 181 474 B1, the coolant channels formed between the bipolar plate layers are tapered locally in order to widen the anode gas flow channels or cathode gas flow channels adjacent to the tapered coolant channels locally.

[0019] However, this reduces the cross-section of the respectively tapering coolant channel through which the coolant can flow locally, which locally reduces the cooling capacity of the bipolar plate. Summary of the Invention

[0020] The object of the present invention is to provide a sufficiently wide area on the anode gas flow channel or on the cathode gas flow channel for connecting the anode-side bipolar plate layers to the cathode-side bipolar plate layers without impairing the cooling function of the bipolar plates.

[0021] In a bipolar plate according to the preamble of claim 1 , according to a first alternative of the invention, this object is achieved in that at least one anode gas flow channel is locally widened in that at least one section of the coolant flow channel adjacent to the anode gas flow channel is locally shifted in a transverse direction of the anode gas flow channel, which is perpendicular to the local longitudinal direction of the anode gas flow channel and is oriented perpendicular to the stacking direction, and a section of another anode gas flow channel adjacent to the locally shifted section of the coolant flow channel is locally narrowed.

[0022] The anode-side bipolar plate layers and the cathode-side bipolar plate layers are materially connected to one another within the locally widened region of the anode gas flow channel and / or within the locally widened region of the cathode gas flow channel at at least one connecting region.

[0023] Furthermore, in a bipolar plate according to the preamble of claim 1, according to the second alternative of claim 1, the object on which the invention is based is achieved in that at least one cathode gas flow channel is locally widened in that at least one section of the coolant flow channel adjacent to the cathode gas flow channel is locally shifted in a transverse direction of the cathode gas flow channel, which is oriented perpendicularly to the local longitudinal direction of the cathode gas flow channel and perpendicularly to the stacking direction, and further cathode gas flow channels adjacent to the locally shifted section of the coolant flow channel are locally narrowed.

[0024] The anode-side bipolar plate layers and the cathode-side bipolar plate layers are materially connected to one another within the locally widened region of the anode gas flow channel and / or within the locally widened region of the cathode gas flow channel at at least one connecting region.

[0025] In a special embodiment of the invention, it is provided that the connecting region is designed as a skip weld seam.

[0026] In a preferred embodiment of the present invention, the extension e of the connection region along the local longitudinal direction of the anode gas flow channel is greater than the width B" of the channel bottom of the anode gas flow channel in the local widening region of the anode gas flow channel. a and / or the extension range e of the connecting region along the local longitudinal direction of the cathode gas flow channel is greater than the width B" of the bottom of the cathode gas flow channel in the local widened region of the cathode gas flow channel k .

[0027] The anode-side bipolar plate layers and the cathode-side bipolar plate layers are preferably welded to one another at this connection region, particularly preferably by laser welding.

[0028] The maximum width B" of the channel bottom of the locally widened area of ​​the anode gas flow channel aOr the maximum width B" of the channel bottom of the locally widened area of ​​the cathode gas flow channel k It is preferably at least 0.1 mm, in particular at least 0.15 mm, particularly preferably at least 0.2 mm.

[0029] The width B of the moving section of the coolant flow channel c It is preferably substantially equal to the width B of the non-moving section of the coolant flow channel adjacent to the moving section. c Same size.

[0030] The flank angle α at which the flanks of the moving section of the coolant flow channel are inclined relative to the contact plane of the anode-side bipolar plate layer and the cathode-side bipolar plate layer perpendicular to the stacking direction a and α k The flank angle α of the flank of the coolant channel section adjacent to the displaced section is preferably substantially inclined relative to the contact plane. a and α k Same size.

[0031] In principle, it is advantageous if only a section of a single coolant flow channel adjacent to the anode gas flow channel moves locally in a transverse direction and further anode gas flow channels adjacent to the coolant flow channel are locally narrowed; and / or if only a section of a single coolant flow channel adjacent to the cathode gas flow channel moves locally in a transverse direction and further cathode gas flow channels adjacent to the coolant flow channel are narrowed.

[0032] In this way, a local asymmetrical widening of the relevant anode gas flow channel or the relevant cathode gas flow channel is achieved.

[0033] In contrast, in another design of the present invention, sections of two coolant channels adjacent to the anode gas channel are locally moved away from each other along the transverse direction, and the other two anode gas channels adjacent to these two coolant channels are locally narrowed; and / or sections of two coolant channels adjacent to the cathode gas channel are locally moved away from each other along the transverse direction, and the other two cathode gas channels adjacent to these two coolant channels are narrowed.

[0034] In this way, a locally symmetrical widening of the relevant anode gas flow channel or the relevant cathode gas flow channel is achieved.

[0035] In this case, it is preferably provided that the displaced sections of the coolant ducts adjacent to the anode gas ducts or cathode gas ducts are displaced locally equally far in the transverse direction relative to the non-displaced sections of these coolant ducts.

[0036] To ensure sufficient electrical conductivity between the bipolar plate layers, the bipolar plate advantageously has multiple connection regions. These connection regions can be unevenly distributed across the bipolar plate or arranged in a regular pattern with a first periodic length P1 along the longitudinal direction of the bipolar plate and a second periodic length P2 along a transverse direction of the bipolar plate, oriented perpendicular to the longitudinal direction and perpendicular to the stacking direction. The periodic length P1 and / or the periodic length P2 can be constant across the entire bipolar plate, vary in different regions of the bipolar plate flow field, or vary along the flow direction of the anode gas and / or cathode gas.

[0037] This makes it possible, for example, to achieve a lower area density of the connection regions in regions of the bipolar plate where the current flow from bipolar plate layer to bipolar plate layer is weaker.

[0038] The concept underlying the two aforementioned alternatives of the present invention is that a sufficiently wide support area for establishing a connecting seam is generated between the bipolar plate layers in that the connecting region is locally widened, not by tapering adjacent coolant channels, but by narrowing two adjacent anode gas flow channels or cathode gas flow channels.

[0039] This results in a widened, flat region which is available for producing a connecting seam, for example a weld seam.

[0040] In this case, at least one of the adjacent coolant channels locally bypasses the connecting region without tapering and returns to its original position immediately after the widened region of the anode gas flow channel or cathode gas flow channel.

[0041] At least one, particularly preferably both, of the respective adjacent anode gas flow channels or cathode gas flow channels tapers locally in order to create space for producing a material-locking connection of the bipolar plate layers at the connecting region.

[0042] The locally widened regions of the anode gas flow channel or of the cathode gas flow channel are preferably repeated at regular intervals across the respective flow field.

[0043] This preferably involves not just one anode gas flow channel or one cathode gas flow channel, but rather a plurality of anode gas flow channels or cathode gas flow channels running parallel to one another.

[0044] In principle, even all anode gas flow channels or cathode gas flow channels can be widened locally, so that a large number of suitable locations are available for the material-bonded connection of the bipolar plate layers to one another.

[0045] In the bipolar plate according to the invention, the flank angles of the coolant channels preferably remain constant even in the region of local widenings of the anode gas flow channel or the cathode gas flow channel.

[0046] The width of the web, at which the membrane electrode assembly rests against one of the bipolar plate layers of the bipolar plate, preferably remains constant even in the region of locally widened anode gas flow channels or cathode gas flow channels.

[0047] If the width of the channel bottom of the anode gas flow channel or the cathode gas flow channel is already roughly sufficient to connect the bipolar plate layers to each other in this area in a material-locked manner, it may be sufficient to allow only one of the adjacent cooling channels to bypass in the transverse direction of the relevant flow channel, while the corresponding other adjacent cooling channel does not bypass in the transverse direction, thereby forming an asymmetric web pattern in the locally widened area of ​​the anode gas flow channel or the cathode gas flow channel.

[0048] Both in the case of a symmetrical local widening of the flow channels and in the case of an asymmetrical local widening of the flow channels, the adjacent anode gas flow channels or cathode gas flow channels are locally constricted.

[0049] In order to achieve sufficient electrical conductivity between the bipolar plate layers of the bipolar plate, the local widening of each anode gas flow channel or each cathode gas flow channel is distributed in a repeating pattern over the corresponding flow field.

[0050] According to a further alternative of the invention, in a bipolar plate having the features of the preamble of claim 11 , the above-mentioned object on which the invention is based is achieved by:

[0051] a) at least one anode gas flow channel has a deflection region, at which the anode gas flow channel changes its throughflow direction, wherein a channel bottom of the deflection region abuts against a channel bottom of the cathode gas flow channel in an overlapping region;

[0052] and / or

[0053] b) at least one cathode gas flow channel has a deflection region, at which the anode gas flow channel changes the throughflow direction of the anode gas flow channel, wherein the channel bottom of the deflection region rests against the channel bottom of the anode gas flow channel in the overlapping region,

[0054] In this case, the anode-side bipolar plate layers and the cathode-side bipolar plate layers are materially connected to one another within the respective overlapping region at at least one connecting region.

[0055] Therefore, the concept underlying this alternative of the present invention is that the flow channels in the flow field are not designed as straight lines, but rather have a meandering structure. This creates deflection regions for the anode gas channel or the cathode gas channel, and intersecting flat support regions between the channel bottoms of the anode and cathode gas channels. These deflection regions can be purposefully left free and designed in a manner suitable for welding as flat welding regions for forming weld seams. These flat welding regions can be repeated periodically across the flow field.

[0056] In a preferred embodiment of the present invention, the extent f of the overlapping region along the local flow direction of the anode gas flow channel in a section before and / or after the turning region of the anode gas flow channel or the extent f of the overlapping region along the local flow direction of the cathode gas flow channel in a section before and / or after the turning region of the cathode gas flow channel is greater than the width B of the channel bottom of the anode gas flow channel outside the corresponding turning region. a Or the width B of the bottom of the cathode gas channel k .

[0057] To ensure sufficient electrical conductivity between the bipolar plate layers of a bipolar plate, the bipolar plate advantageously has a plurality of turning regions. These turning regions can be unevenly distributed across the bipolar plate or arranged in a regular pattern having a first periodic length P1 along the longitudinal direction of the bipolar plate and a second periodic length P2 along a transverse direction of the bipolar plate oriented perpendicular to the longitudinal direction and perpendicular to the stacking direction. The periodic length P1 and / or the periodic length P2 can be constant across the bipolar plate, vary in different regions of the flow field of the bipolar plate, or change along the flow direction of the anode gas and / or cathode gas. This can, for example, achieve a lower area density of the turning regions in regions of the bipolar plate where the current flow from bipolar plate layer to bipolar plate layer is weaker, thereby also achieving a lower area density of the connection region.

[0058] The bipolar plate according to the invention according to each of the above-mentioned alternatives is particularly suitable for use in an electrochemical device comprising a plurality of electrochemical cells which follow one another in the stacking direction and each comprise a bipolar plate according to the invention.

[0059] Such an electrochemical device may be, for example, a fuel cell device or an electrolysis apparatus.

[0060] The electrochemical cell in which the bipolar plate according to the invention is used preferably comprises a polymer electrolyte membrane.

[0061] Further features and advantages of the invention are the subject of the following description and drawings of exemplary embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In the attached figure:

[0063] Figure 1 A top view of the anode side of a bipolar plate of an electrochemical cell for an electrochemical device is shown, the electrochemical device comprising a plurality of electrochemical cells which follow one another in a stacking direction, wherein the bipolar plate comprises an electrochemically active area comprising an anode gas flow field through which an anode gas can flow transversely to the stacking direction, a cathode gas flow field through which a cathode gas can flow transversely to the stacking direction, and a coolant flow field through which a coolant can flow transversely to the stacking direction.

[0064] The anode gas flow field includes an anode gas flow channel through which the anode gas can flow, the cathode gas flow field includes a cathode gas flow channel through which the cathode gas can flow, and the coolant flow field includes a coolant flow channel through which the coolant can flow.

[0065] The anode gas flow field is constructed on the bipolar plate layer on the anode side, and the cathode gas flow field is constructed on the bipolar plate layer on the cathode side.

[0066] The anode gas flow channel is locally widened by locally shifting a section of the coolant flow channel adjacent to the anode gas flow channel in a transverse direction of the anode gas flow channel that is perpendicular to the local longitudinal direction of the anode gas flow channel and perpendicular to the stacking direction, and locally narrowing sections of other anode gas flow channels that are respectively adjacent to the locally shifted sections of the coolant flow channel, and

[0067] wherein the anode-side bipolar plate layer and the cathode-side bipolar plate layer are connected to one another in a materially bonded manner at a connection region within the locally widened region of the anode gas flow channel, preferably by welding;

[0068] Figure 2 The diagram shows the area outside the local widening of the anode gas flow channel along the Figure 1 The line 2-2 passes through Figure 1 Cross section of the bipolar plate in;

[0069] Figure 3 The diagram shows the local widening of the anode gas flow channel along the Figure 1 The line 3-3 passes through Figure 1 Cross section of the bipolar plate in;

[0070] Figure 4shows a top view of the anode side of a bipolar plate having a plurality of connection regions, which are each arranged in the region of a local widening of an anode gas flow channel and are also arranged in a regular pattern having a first period length P1 in the longitudinal direction of the bipolar plate and a second period length P2 in a transverse direction of the bipolar plate oriented perpendicularly to the longitudinal direction and perpendicularly to the stacking direction;

[0071] Figure 5 A top view of the anode side of a bipolar plate is shown, the bipolar plate having a plurality of connection regions, which are each arranged in a locally widened region of an anode gas flow channel, wherein the local widening of the anode gas flow channel is achieved by locally shifting only a section of the coolant flow channel adjacent to the anode gas flow channel in a transverse direction of the anode gas flow channel and locally narrowing only a section of another anode gas flow channel adjacent to the locally shifted section of the coolant flow channel, and wherein, furthermore, the connection regions are arranged in a regular pattern having a first period length P1 in the longitudinal direction of the bipolar plate and a second period length P2 in a transverse direction of the bipolar plate oriented perpendicularly to the longitudinal direction and perpendicularly to the stacking direction;

[0072] Figure 6 The anode side of a bipolar plate of an electrochemical cell for an electrochemical device is shown, the electrochemical device comprising a plurality of electrochemical cells which follow one another in a stacking direction, wherein the bipolar plate comprises an electrochemically active area comprising an anode gas flow field through which an anode gas can flow transversely to the stacking direction, a cathode gas flow field through which a cathode gas can flow transversely to the stacking direction, and a coolant flow field through which a coolant can flow transversely to the stacking direction.

[0073] The anode gas flow field includes an anode gas flow channel through which the anode gas can flow, the cathode gas flow field includes a cathode gas flow channel through which the cathode gas can flow, and the coolant flow field includes a coolant flow channel through which the coolant can flow.

[0074] The anode gas flow field is constructed on the bipolar plate layer on the anode side, and the cathode gas flow field is constructed on the bipolar plate layer on the cathode side.

[0075] wherein at least one anode gas flow channel has a deflection region, in which the anode gas flow channel changes its flow direction by 180°, wherein the channel bottom of the deflection region rests against the channel bottom of the cathode gas flow channel in two overlapping regions, and

[0076] wherein the anode-side bipolar plate layers and the cathode-side bipolar plate layers are connected to one another in a materially bonded manner at the connection region within the respective overlapping region, preferably by welding;

[0077] Figure 7 The anode gas flow channel is shown outside the turning area along Figure 6 The line 7-7 passes through Figure 6 a cross section of a bipolar plate in; and

[0078] Figure 8 The figure shows the direction of the anode gas flow channel along the turning area. Figure 6 The line 8-8 passes through Figure 6 Cross section of a bipolar plate in FIG.

[0079] Identical or functionally equivalent elements are provided with the same reference numerals in all figures. DETAILED DESCRIPTION

[0080] exist Figures 1 to 3 The bipolar plate 100 shown in the center section forms a component of an electrochemical cell (not shown in its entirety) of an electrochemical device, which comprises a plurality of such electrochemical cells that follow one another in a stacking direction 102 .

[0081] The bipolar plate 100 comprises an anode-side bipolar plate layer 104 and a cathode-side bipolar plate layer 106 , which lie against one another (preferably flatly) along a contact plane 108 of the bipolar plate 100 oriented perpendicular to the stacking direction 102 and are connected to one another in a materially bonded manner, in particular by welding (e.g., by laser welding), at a connection region 150 , which will be described in more detail below.

[0082] Each of the bipolar plate layers 104 , 106 is preferably formed from a substantially flat raw material, in particular from a raw sheet material, by a forming process, which may be, in particular, an embossing process or a deep-drawing process.

[0083] The raw material is a conductive material, preferably a metal material, such as stainless steel.

[0084] The starting material can be provided with a coating, in particular a highly electrically conductive coating.

[0085] As a result of this shaping process, grooves 112 are formed on the anode-side bipolar plate layer 104 or on the cathode-side bipolar plate layer 106 , which grooves themselves extend from the contact plane 108 .

[0086] Each of the grooves 112 comprises two groove feet 114 , two groove flanks 116 and a groove top 118 connecting the groove flanks 116 to one another.

[0087] The groove top 118 is preferably of substantially flat design and is preferably oriented substantially perpendicularly to the stacking direction 102 .

[0088] In the assembled state of the electrochemical device, the groove tops 118 of the anode-side bipolar plate layer 104 carry structural elements of the electrochemical cell, preferably the anode-side gas diffusion layer.

[0089] In the assembled state of the electrochemical device, the grooves 112 of the cathode-side bipolar plate layer 106 also carry components of the electrochemical cell, preferably the cathode-side gas diffusion layer.

[0090] In the bipolar plate 100 Figures 1 to 3 In the unloaded rest state shown in FIG, the groove flank 116 of the groove 112 of the bipolar plate layer 104 on the anode side and the contact plane 108 of the bipolar plate 100 form a flank angle α a .

[0091] In the loaded state of the electrochemical device, the electrochemical cells of the electrochemical device are pressed against one another by means of a clamping device (not shown), in which the flank angle α′ a The wing angle α is different from the rest state a ; Usually, the flank angle α' a The flank angle α relative to the rest state due to the electrochemical unit being in the compressed state a Has decreased.

[0092] exist Figures 1 to 3 In the unloaded rest state of the bipolar plate 100 shown in FIG, the groove flanks 116 of the grooves 112 of the bipolar plate layer 106 on the cathode side are formed at a flank angle α with the contact plane 108 of the bipolar plate 100. k .

[0093] exist Figures 1 to 3 In the embodiment of the bipolar plate 100 shown in FIG, the anode-side bipolar plate layer 104 and the cathode-side bipolar plate layer 106 are designed to be mirror-symmetrical to each other with respect to the contact plane 108, so that the flank angle α of the groove 112 of the anode-side bipolar plate layer 104 is a and the flank angle α of the groove 112 of the bipolar plate layer 106 on the cathode side k However, it is also conceivable that the anode-side bipolar plate layer 104 and the cathode-side bipolar plate layer 106 are not designed to be mirror-symmetrical with respect to the contact plane 108; in this case, the flank angle α of the groove 112 of the anode-side bipolar plate layer 104 is a The flank angle α of the groove 112 of the bipolar plate layer 106 on the cathode side may be different from k .

[0094] The grooves 112 of the anode-side bipolar plate layer 104 themselves each extend along a local longitudinal direction 120 .

[0095] The grooves 112 of the cathode-side bipolar plate layer 106 themselves each extend along a local longitudinal direction 122 .

[0096] The groove top 118 of the groove 112 of the bipolar plate layer 104 on the anode side has a web width S of the anode side. a The anode-side web width corresponds to the extent of the trough top 118 perpendicular to the local longitudinal direction 120 of the anode-side trough 112 .

[0097] The groove top 118 of the groove 112 of the bipolar plate layer 106 on the cathode side has a web width S k , which corresponds to the extent of the cathode-side groove top 118 perpendicular to the local longitudinal direction 122 of the cathode-side groove 112 .

[0098] exist Figures 1 to 3 In the symmetrical embodiment of the bipolar plate 100 shown in FIG, the web width S on the anode side a The web width S on the cathode side k consistent.

[0099] However, it can also be provided in principle that the web width S on the anode side a Different from the web width S on the cathode side k .

[0100] For example, it can be provided that the web width S on the anode side a Greater than the cathode side web width S k .

[0101] An anode gas flow channel 126 is formed in an area surrounded by the groove side wings 116 of two adjacent grooves 112 of the anode-side bipolar plate layer 104 and the channel bottom 124 of the anode-side bipolar plate layer 104 connecting the groove feet 114 of the two adjacent grooves 112.

[0102] Each anode gas flow channel 126 has a channel width B a The channel width corresponds to the spacing of the groove feet 114 of the grooves 112 of the anode-side bipolar plate layer 104 that border the corresponding anode gas flow channels 126, perpendicular to the local longitudinal direction 120 of the anode-side grooves 112. The anode gas flow channels 126 themselves extend along the local longitudinal direction 120 of the grooves 112 of the anode-side bipolar plate layer 104 that border the anode gas flow channels 126.

[0103] The groove side wings 116 of the adjacent grooves 112 of the bipolar plate layer 106 on the cathode side and the channel bottoms 124 connecting the groove feet 114 of the adjacent grooves 112 together surround the cathode gas flow channels 128 respectively.

[0104] Each cathode gas flow channel 128 has a channel width B k The channel width corresponds to the spacing between the groove feet 114 of the grooves 112 of the cathode-side bipolar plate layer 106 that surround the cathode gas flow channels 128 and are perpendicular to the local longitudinal direction 122 of the cathode-side grooves 122. The cathode gas flow channels 128 themselves extend along the local longitudinal direction 122 of the grooves 112 of the cathode-side bipolar plate layer 106 that surround the cathode gas flow channels 128.

[0105] exist Figures 1 to 3 In the embodiment of the symmetrically constructed bipolar plate 100 shown in FIG, the width B of the anode gas flow channel is a The width B of the cathode gas flow channel 128 k Same size.

[0106] However, in principle, the width B of the anode gas flow channel 126 a The width B of the cathode gas flow channel 128 may be different from k .

[0107] For example, the width B of the anode gas flow channel 126 may be set to a Smaller than the width B of the cathode gas flow channel 128 k .

[0108] The inner surfaces of the grooves 112 of the anode-side bipolar plate layer 104 and the grooves 112 of the cathode-side bipolar plate layer 106 facing each other together define coolant flow channels 130 constructed between the anode-side bipolar plate layer 104 and the cathode-side bipolar plate layer 106 .

[0109] Each of the coolant flow channels 130 has a width B c The width corresponds to the maximum extent of the cavity bounded by the adjacent grooves 112 of the anode-side bipolar plate layer 104 and the cathode-side bipolar plate layer 106 , perpendicular to the respective local longitudinal direction 132 of the coolant flow channel 130 .

[0110] The anode gas flow channels 126 of the bipolar plate 100 together form an anode gas flow field 134 configured on the bipolar plate layer 104 on the anode side of the bipolar plate 100 .

[0111] The cathode gas flow channels 128 together form a cathode gas flow field 136 configured on the bipolar plate layer 106 on the cathode side of the bipolar plate 100 .

[0112] The coolant flow channels 130 together form a coolant flow field 138 of the bipolar plate 100 , which is configured between the anode-side bipolar plate layer 104 and the cathode-side bipolar plate layer 106 .

[0113] In the assembled state of the electrochemical device, the anode gas flow field 134 of each bipolar plate 100 is fluidly connected to at least one anode gas delivery channel extending parallel to the stacking direction 102, through which anode gas (fuel gas, which preferably contains hydrogen) can be delivered to the anode gas flow field 134, and the anode gas flow field is fluidly connected to at least one anode gas exhaust channel extending parallel to the stacking direction 102, through which anode gas can be exhausted from the anode gas flow field 134.

[0114] In the assembled state of the electrochemical device, the cathode gas flow field 136 of each bipolar plate 100 maintains fluid connection with at least one cathode gas delivery channel extending parallel to the stacking direction 102, through which cathode gas (oxidant, which preferably contains oxygen) can be delivered to the cathode gas flow field 136, and the cathode gas flow field maintains fluid connection with at least one cathode gas exhaust channel extending parallel to the stacking direction 102, through which cathode gas can be discharged from the cathode gas flow field 136.

[0115] In the assembled state of the electrochemical device, the coolant flow field 138 of each bipolar plate 100 is fluidly connected to at least one coolant delivery channel extending parallel to the stacking direction 102, through which coolant (preferably liquid coolant, such as water) can be delivered to the coolant gas flow field 138, and the coolant gas flow field is fluidly connected to at least one coolant discharge channel extending parallel to the stacking direction 102, through which coolant can be discharged from the coolant flow field 138.

[0116] Hereinafter, the region of the bipolar plate 100 including the anode gas flow field 134 , the cathode gas flow field 136 , and the coolant flow field 138 is referred to as the electrochemically active region 140 of the bipolar plate 100 , even though no electrochemical reactions occur in these flow fields themselves.

[0117] Since the bipolar plate 100 must be able to achieve charge balance between the membrane electrode units adjacent to the bipolar plate 100 , the bipolar plate layers 104 , 106 are formed of a material having good electrical conductivity.

[0118] Preferably, the material of the bipolar plate layers 104 , 106 has a specific resistance of less than 15 Ω·mm² / m.

[0119] For example, the anode-side bipolar plate layer 104 and / or the cathode-side bipolar plate layer 106 may be formed of austenitic stainless steel, preferably steel having a material number of 1.4404.

[0120] The specific resistivity of steel with raw material number 1.4404 is about 0.75 Ω·mm 2 / m.

[0121] This steel has a natural passive layer (chromium oxide layer) formed on its surface, which has a low electrical conductivity. Therefore, it is necessary to provide the bipolar plates 100 with an electrically conductive coating on their outer sides facing the electrodes of the membrane electrode unit.

[0122] If the inner sides of the bipolar plate layers 104 and 106 facing each other are not provided with such an electrically conductive coating, these inner sides of the bipolar plate layers 104 and 106 must be materially connected to each other in order to ensure the required electrical conductivity between the bipolar plate layers 104 and 106 of the bipolar plate 100 .

[0123] Such a cohesive connection can be produced, for example, by a weld seam, wherein the weld seam is interrupted and can comprise weld seam sections (skip weld seams) or weld points (spot welds) separated from one another.

[0124] Such a welded connection can be produced in particular by laser welding.

[0125] In order to weld such an electrically conductive seam, the region on which the welding should be performed and in which the anode-side bipolar plate layer 104 and the cathode-side bipolar plate layer 106 can rest against each other and be welded to each other and whose width corresponds to the width of the channel bottom 124 of the anode gas flow channel 126 and / or the width of the channel bottom 124 of the cathode gas flow channel 128 must have a minimum width due to the accumulation of manufacturing tolerances, which are caused, for example, by tolerances in the width of the weld seam, tolerances in the positioning of the weld seam relative to the bipolar plate layers 104, 106 and tolerances in the relative positioning of the bipolar plate layers 104 and 106 with respect to each other.

[0126] The minimum channel width is, for example, in the range of at least 0.2 mm.

[0127] In order to avoid having to design all anode gas flow channels 126 and / or cathode gas flow channels 128 with such a large channel bottom width over their entire length, Figures 1 to 3 In the embodiment of the bipolar plate 100 shown in FIG, it is provided that at least one anode gas flow channel 126 is locally widened in such a way that the sections 142 of the two coolant flow channels 130 adjacent to the anode gas flow channel 126, which are adjacent to the relevant anode gas flow channel 126, are each locally shifted by a distance V along a transverse direction 144 of the anode gas flow channel 126, which is perpendicular to the local longitudinal direction 120 of the anode gas flow channel 126 and is oriented perpendicular to the stacking direction 102 (see FIG. Figure 1 ).

[0128] Here, the two coolant flow channels 130 adjacent to the locally widened anode gas flow channel 126 maintain their full width B not only in the displaced section 142 of the corresponding coolant flow channel 142 but also in the transition section 146 located before or after the displaced section 142. c , so that the local cross-sections of these coolant flow channels 130 through which the coolant can flow remain unchanged, and thus sufficient cooling is also ensured in the locally widened regions of the anode gas flow channels 126 .

[0129] In order to compensate for the offset V of the coolant flow channel 130 adjacent to the locally widened anode gas flow channel 126 in the transverse direction 144, the other anode gas flow channels 126' adjacent to the locally shifted sections 142 of the coolant flow channel 130 are locally narrowed, more precisely, the channel width B' a Compared to the width B of the anode gas flow channel 126 ′ in front of or behind the locally narrowed region 146 a The offset V is reduced.

[0130] The coolant flow channels 130 ′ adjacent to these locally narrowed anode gas flow channels 126 ′ are then again configured without an offset V in the transverse direction 144 in the locally widened regions of the anode gas flow channels 126 .

[0131] In the locally widened region 148 of the anode gas flow channel 126 formed by the offset V of the two adjacent coolant flow channels 130 , the anode-side bipolar plate layer 104 and the cathode-side bipolar plate 106 are materially connected to one another at a connection region 150 .

[0132] The integrally bonded connection in the connection region 150 can be designed, in particular, as a weld seam 152 , in particular as a jump weld seam 154 , which connects the two bipolar plate layers 104 and 106 to one another.

[0133] The extension e of the connecting region 150 along the local longitudinal direction 120 of the widened anode gas flow channel 126 is preferably greater than the width B″ of the channel bottom 124 of the anode gas flow channel 126 in the locally widened region 148 of the anode gas flow channel 126. a .

[0134] The maximum width B"a of the channel bottom 124 of the locally widened region 148 of the anode gas flow channel 126 is preferably at least 0.10 mm, in particular at least 0.15 mm, particularly preferably at least 0.2 mm.

[0135] like Figure 3As can be clearly seen in the figure, the flanks 116 of the moved section 142 of the locally moved coolant flow channel 130 are inclined relative to the contact plane 108 of the anode-side bipolar plate layer 104 and the cathode-side bipolar plate layer 106 perpendicular to the stacking direction 102 by a flank angle α a , α k The flank angle α at which the flank 116 of the section 143 of the coolant channel 130 adjacent to the displaced section 142 is inclined relative to the contact plane 108 is substantially a , α k Same size (see Figure 2 ).

[0136] exist Figures 1 to 3 In the embodiment of the bipolar plate 100 shown in FIG, two moved sections 142 of the coolant flow channel 130 adjacent to the locally widened anode gas flow channel 126 are locally moved equally far along the transverse direction 144 relative to the non-moving sections 143 of these coolant flow channels 130, i.e., moved by the same offset V.

[0137] Because in Figures 1 to 3 In the embodiment of the bipolar plate 100 shown in the figure, the cathode gas flow channel 128 is constructed to be mirror-symmetrical to the anode gas flow channel 126 about the contact plane 108, so in this bipolar plate 100, at least one cathode gas flow channel 128 is also locally widened in the following manner, that is, the two sections 142 of the two coolant flow channels 130 adjacent to the cathode gas flow channel 128 are locally moved by an offset V in a transverse direction 144 of the cathode gas flow channel 128 that is perpendicular to the local longitudinal direction 122 of the cathode gas flow channel 128 and oriented perpendicular to the stacking direction 102.

[0138] Furthermore, two further cathode gas flow channels 128 ′, each adjacent to these partially displaced sections 142 of the coolant flow channel 130 , are locally narrowed.

[0139] As a result, the relevant cathode gas flow channel 128 also has a locally widened region 148 , wherein the anode-side bipolar plate layer 104 and the cathode-side bipolar plate layer 106 are materially connected to each other at a connecting region 150 within this locally widened region 148 of the cathode gas flow channel 128 .

[0140] The extension e of the connecting region 150 along the local longitudinal direction 122 of the cathode gas flow channel 128 is preferably greater than the width B″ of the channel bottom 124 of the cathode gas flow channel 128 in the locally widened region 148 of the cathode gas flow channel 128. k .

[0141] The maximum width B" of the channel bottom 124 of the locally widened region 148 of the cathode gas flow channel 128 kIt is preferably at least 0.10 mm, in particular at least 0.15 mm, particularly preferably at least 0.2 mm.

[0142] In order to generate sufficient electrical conductivity between the bipolar plate layers 104 and 106 of the bipolar plate 100, the bipolar plate 100, such as Figure 4 As can be seen, there are multiple connection areas 150, which are respectively arranged in the locally widened areas 148 of the anode gas flow channel 126 (or the cathode gas flow channel 128), and are preferably arranged in a regular pattern, which has a first period length P1 along the longitudinal direction 156 of the bipolar plate 100 and a second period length P2 along the transverse direction 158 of the bipolar plate 100 perpendicular to the longitudinal direction 156 of the bipolar plate 100 and perpendicular to the stacking direction 102.

[0143] In this case, the longitudinal direction 156 of the bipolar plate 100 is preferably oriented parallel to the local longitudinal direction 120 of the anode gas flow channels 126 extending in the main flow direction of the anode gas.

[0144] exist Figures 1 to 4 The bipolar plate 100 shown in Figure 5 In the variant shown in , the locally widened area 148 of the anode gas flow channel 126 is produced in such a way that, respectively, only a section 142 of a single coolant flow channel 130 adjacent to the anode gas flow channel 126 is locally moved along the transverse direction 144 of the anode gas flow channel 126, and only a section 146 of another anode gas flow channel 126' adjacent to the locally moved section 142 of the coolant flow channel 130 is locally narrowed.

[0145] Therefore, in this embodiment, the locally widened region 148 of the anode gas flow channel 126 is oriented with respect to a plane spanned by the local longitudinal direction 120 of the anode gas flow channel 126 and the stacking direction 102. No Symmetrically constructed.

[0146] like Figure 5 As shown in , even in this asymmetric design of the locally widened region 148 of the anode gas flow channel 126, it can be provided that the connection regions 150 arranged in the locally widened region 148 of the anode gas flow channel 126 are arranged in a regular pattern, which regular pattern has a first period length P1 along the longitudinal direction 156 of the bipolar plate 100 and has a second period length P2 along the transverse direction 158 of the bipolar plate 100 oriented perpendicular to the longitudinal direction 156 of the bipolar plate 100 and perpendicular to the stacking direction 102.

[0147] In addition, Figure 5The embodiment of the bipolar plate 100 shown in FIG. 1 is similar in structure, function, and manufacturing method to that in FIG. Figures 1 to 4 The embodiment of the bipolar plate 100 shown in FIG. 1 is identical and reference is made to it in this respect.

[0148] exist Figures 6 to 8 , an alternative possibility for providing a locally widened section of the anode gas flow channel 126 is shown.

[0149] In this case, if Figure 6 As can be clearly seen in FIG, the anode gas flow channel 126 has a deflection region 160, at which the anode gas flow channel 126 changes the flow direction 164 of the anode gas flow channel by 180°, wherein the channel bottom 124 of the deflection region 160 rests on the channel bottom 124 of the cathode gas flow channel 128 in two overlapping regions 162 (see FIG. Figure 8 ).

[0150] In each of the two overlapping regions 162 of the deflection region 160 , the anode-side bipolar plate layer 104 and the cathode-side bipolar plate layer 106 are respectively connected to one another in a materially bonded manner at a connection region 150 , preferably by welding, in particular by laser welding.

[0151] To enable this, the extent f of the deflection region 160 of the anode gas channel 126 along the local longitudinal direction 120 of the anode-side groove 112 is greater than the extent e of the respective connecting region 150 along the same local longitudinal direction 120 .

[0152] A large gap is provided between the two connecting regions 150 of the deflection region 160 , within which gap the positioning of the connecting regions 150 can be varied perpendicularly to the local longitudinal direction 120 of the anode-side slot 112 .

[0153] Furthermore, an extent f of each overlapping region 162 along a local through-flow direction 164 of the anode gas flow channel 126 in the section 126a of the anode gas flow channel 126 located upstream of the turning region 160 and / or in the section 126b of the anode gas flow channel 126 located downstream of the turning region 160 is greater than a width B of the channel bottom of the anode gas flow channel 126 outside the corresponding turning region 160. a .

[0154] In order to generate sufficient electrical conductivity between the bipolar plate layers 104 and 106 of the bipolar plate 100, Figures 6 to 8The embodiment of the bipolar plate 100 shown in the figure preferably has a plurality of turning regions 160 arranged in a regular pattern having a first period length P1 along the longitudinal direction 156 of the bipolar plate 100 and a second period length P2 along the transverse direction 158 of the bipolar plate 100 oriented perpendicular to the longitudinal direction 156 of the bipolar plate 100 and perpendicular to the stacking direction 102.

[0155] In this case, the longitudinal direction 156 of the bipolar plate 100 is preferably oriented parallel to the local longitudinal direction 120 of the anode gas flow channels 126 extending in the main flow direction of the anode gas.

[0156] exist Figures 6 to 8 In a variant of the embodiment of the bipolar plate 100 shown in the drawing, it is provided that at least one cathode gas flow channel 128 has a turning area 160, at which the cathode gas flow channel changes its flow direction, wherein the channel bottom 124 of the turning area 160 rests on the channel bottom 124 of the anode gas flow channel 126 in an overlapping area 162, wherein the bipolar plate layer 104 on the anode side and the bipolar plate layer 106 on the cathode side are materially connected to each other at the connection area within the corresponding overlapping area 160.

[0157] Preferably, two such overlapping regions 162 are respectively provided in the deflection region of the cathode gas flow channel, in which overlapping regions the bipolar plate layer 104 on the anode side and the bipolar plate layer 106 on the cathode side are respectively connected to each other materially at the connection region 150, preferably by welding, for example by laser welding.

[0158] Here, the extent f of the overlapping region 162 along the local through-flow direction of the cathode gas flow channel 128 in the section 128a of the cathode gas flow channel 128 located upstream of the flow deflection region 160 of the cathode gas flow channel 128 and / or in the section 128b of the cathode gas flow channel 128 located downstream of the deflection region 160 of the cathode gas flow channel 128 is preferably greater than the width B of the channel bottom 124 of the cathode gas flow channel 128 outside the corresponding deflection region 160. k .

[0159] The turning regions 160 of the cathode gas flow channels 128 may also be arranged in a regular pattern on the bipolar plate 100 , the regular pattern having a first period length P1 along the longitudinal direction 156 of the bipolar plate 100 and a second period length P2 along the transverse direction 158 of the bipolar plate 100 oriented perpendicular to the longitudinal direction 156 and perpendicular to the stacking direction 102 .

[0160] The bipolar plate 100 described above is suitable for use in an electrochemical device comprising a plurality of electrochemical cells which follow one another in a stacking direction 102 and each comprise a bipolar plate 100 .

Claims

1. A bipolar plate for an electrochemical cell of an electrochemical device, the electrochemical device comprising a plurality of electrochemical cells, the electrochemical cells being arranged one after the other in a stacking direction (102), in, The bipolar plate (100) comprises the following: an electrochemically active region (140), the electrochemically active region comprising an anode gas flow field (134) through which anode gas can flow transversely to the stacking direction (102), a cathode gas flow field (136) through which cathode gas can flow transversely to the stacking direction (102), and a coolant flow field (138) through which coolant can flow transversely to the stacking direction, The anode gas flow field (134) includes an anode gas flow channel (126) through which anode gas can flow, the cathode gas flow field (136) includes a cathode gas flow channel (128) through which cathode gas can flow, and the coolant flow field (138) includes a coolant flow channel (130) through which coolant can flow. The anode gas flow field (134) is constructed on the bipolar plate layer (104) on the anode side, and the cathode gas flow field (136) is constructed on the bipolar plate layer (106) on the cathode side. It is characterized in that a) locally widening at least one anode gas flow channel (126) by locally shifting at least one section (142) of a coolant flow channel (130) adjacent to the anode gas flow channel (126) in a transverse direction (144) of the anode gas flow channel (126) perpendicular to the local longitudinal direction (120) of the anode gas flow channel (126) and perpendicular to the stacking direction (102), and locally narrowing a section (146) of another anode gas flow channel (126') adjacent to the locally shifted section (142) of the coolant flow channel (130), and / or b) locally widening at least one cathode gas flow channel (128) by locally shifting at least one section (142) of the coolant flow channel (130) adjacent to the cathode gas flow channel (128) in a transverse direction (144) of the cathode gas flow channel (128) perpendicular to the local longitudinal direction (122) of the cathode gas flow channel (128) and perpendicular to the stacking direction (102), and locally narrowing another cathode gas flow channel (128') adjacent to the locally shifted section (142) of the coolant flow channel (130), The anode-side bipolar plate layer (104) and the cathode-side bipolar plate layer (106) are materially connected to each other at at least one connection region (150) within a locally widened region (148) of the anode gas flow channel (126) and / or within a locally widened region (148) of the cathode gas flow channel (128).

2. The bipolar plate layer according to claim 1, It is characterized in that The connecting region (150) is designed as a jump weld seam (154).

3. The bipolar plate layer according to any one of claims 1 or 2, It is characterized in that The extension (e) of the connection region (150) along the local longitudinal direction (120) of the anode gas flow channel (126) is greater than the width (B") of the channel bottom (124) of the anode gas flow channel (126) in the local widened region (148) of the anode gas flow channel (126). a ); and / or an extension (e) of the connection region (150) along the local longitudinal direction (122) of the cathode gas flow channel (128) is greater than a width (B") of the channel bottom (124) of the cathode gas flow channel (128) in the locally widened region (148) of the cathode gas flow channel (128) k ).

4. The bipolar plate according to any one of claims 1 to 3, It is characterized in that The anode-side bipolar plate layer (104) and the cathode-side bipolar plate layer (106) are welded to each other at the connection region (150).

5. The bipolar plate according to any one of claims 1 to 4, It is characterized in that The maximum width (B") of the channel bottom (124) of the locally widened region (148) of the anode gas flow channel (126) a ) or the maximum width (B") of the channel bottom (124) of the locally widened region (148) of the cathode gas flow channel (128) k ) is at least 0.1 mm.

6. The bipolar plate according to any one of claims 1 to 5, It is characterized in that The width (B) of the moving section (142) of the coolant flow channel (130) c ) is substantially the same as the width (B) of the non-moving section (143) of the coolant flow channel (130) adjacent to the moving section (142) c ) are the same size.

7. The bipolar plate according to any one of claims 1 to 6, It is characterized in that The flank (116) of the moving section (142) of the coolant flow channel (130) is tilted relative to the contact plane (108) of the bipolar plate layer (104) on the anode side and the bipolar plate layer (106) on the cathode side, perpendicular to the stacking direction (102), by a flank angle (α a , α k ) is substantially the same as the flank angle (α) at ​​which the flank (116) of the section (143) of the coolant channel (130) adjacent to the moved section (142) is inclined relative to the contact plane (108). a , α k ) are the same size.

8. The bipolar plate layer according to any one of claims 1 to 7, It is characterized in that The sections (142) of the two coolant flow channels (130) adjacent to the anode gas flow channel (126) are locally moved away from each other along the transverse direction (144), and the other two anode gas flow channels (126') adjacent to the two coolant flow channels (130) are locally narrowed; and / or The sections (142) of the two coolant flow channels (130) adjacent to the cathode gas flow channels (128) are locally moved away from each other along the transverse direction (144), and the other two cathode gas flow channels (128') adjacent to the two coolant flow channels (130) are narrowed.

9. The bipolar plate according to claim 8, It is characterized in that The movable section (142) of the coolant channel (130) adjacent to the anode gas channel (126) or the cathode gas channel (128) is locally moved the same distance along the transverse direction (144) as the non-moving section (143) of the coolant channel (130).

10. The bipolar plate according to claims 1 to 7, It is characterized in that Only a section (142) of a single coolant flow channel (130) adjacent to the anode gas flow channel (126) is locally moved in a transverse direction (144), and another anode gas flow channel (146) adjacent to the coolant flow channel (130) is locally narrowed; and / or only a section (142) of a single coolant flow channel (130) adjacent to the cathode gas flow channel (128) is locally moved in a transverse direction (144), and another cathode gas flow channel (128) adjacent to the coolant flow channel (130) is narrowed, wherein, in this way, a locally asymmetric widening portion (148) of the relevant anode gas flow channel (126) or the relevant cathode gas flow channel (128) is achieved.

11. The bipolar plate according to any one of claims 1 to 10, It is characterized in that The bipolar plate (100) has a plurality of connection areas (150) arranged in a regular pattern having a first period length (P1) along a longitudinal direction (156) of the bipolar plate (100) and a second period length (P2) along a transverse direction (158) of the bipolar plate (100) oriented perpendicular to the longitudinal direction (156) and perpendicular to the stacking direction (102).

12. A bipolar plate for an electrochemical cell of an electrochemical device, the electrochemical device comprising a plurality of electrochemical cells, the electrochemical cells being arranged one after the other in a stacking direction (102), in, The bipolar plate (100) comprises the following: an electrochemically active region (140), the electrochemically active region comprising an anode gas flow field (134) through which anode gas can flow transversely to the stacking direction (102), a cathode gas flow field (136) through which cathode gas can flow transversely to the stacking direction (102), and a coolant flow field (138) through which coolant can flow transversely to the stacking direction (102), The anode gas flow field (134) includes an anode gas flow channel (126) through which anode gas can flow, the cathode gas flow field (136) includes a cathode gas flow channel (128) through which cathode gas can flow, and the coolant flow field (138) includes a coolant flow channel (130) through which coolant can flow. The anode gas flow field (134) is constructed on the bipolar plate layer (104) on the anode side, and the cathode gas flow field (136) is constructed on the bipolar plate layer (106) on the cathode side. It is characterized in that a) at least one anode gas flow channel (126) has a deflection region (160), at which the anode gas flow channel changes a flow direction (164) of the anode gas flow channel, wherein the channel bottom (124) of the deflection region (160) abuts against the channel bottom (124) of the cathode gas flow channel (128) in an overlapping region (162); and / or b) at least one cathode gas flow channel (128) has a deflection region (160), at which the cathode gas flow channel changes the flow direction (164) of the cathode gas flow channel, wherein the channel bottom (124) of the deflection region (160) abuts against the channel bottom (124) of the anode gas flow channel (126) in an overlapping region (162), The anode-side bipolar plate layer (104) and the cathode-side bipolar plate layer (106) are materially connected to one another at at least one connection region (150) within a corresponding overlapping region (160).

13. The bipolar plate according to claim 12, It is characterized in that The extension (e) of the connecting region (150) along the local through-flow direction (164) of the anode gas flow channel (126) in the section (126a, 126b) before and / or after the turning region (160) of the anode gas flow channel (126) or the extension (e) of the connecting region (150) along the local through-flow direction (164) of the cathode gas flow channel (128) in the section (128a, 128b) before and / or after the turning region (160) of the cathode gas flow channel (128) is greater than the width (B) of the channel bottom (124) of the anode gas flow channel (126) outside the corresponding turning region (160). a ) or the width (B k ).

14. The bipolar plate according to any one of claims 12 or 13, It is characterized in that The extent (f) of the overlapping region (162) along the local through-flow direction (164) of the anode gas flow channel (126) in the section (126a, 126b) before and / or after the turning region (160) of the anode gas flow channel (126) or the extent (f) of the overlapping region (162) along the local through-flow direction (164) of the cathode gas flow channel (128) in the section (128a, 128b) before and / or after the turning region (160) of the cathode gas flow channel (128) is greater than the width (B) of the channel bottom (124) of the anode gas flow channel (126) outside the corresponding turning region (160). a ) or the width (B k ).

15. The bipolar plate according to any one of claims 12 to 14, It is characterized in that The bipolar plate (100) has a plurality of turning regions (160) arranged in a regular pattern having a first period length (P1) along a longitudinal direction (156) of the bipolar plate (100) and a second period length (P2) along a transverse direction (158) of the bipolar plate (100) oriented perpendicular to the longitudinal direction (156) and perpendicular to the stacking direction (102).

16. An electrochemical device comprising a plurality of electrochemical cells which follow one another in a stacking direction (102) and each comprise a bipolar plate (100) according to any one of claims 1 to 15.

Images