Embossed bipolar plate

Abstract

The invention relates to a bipolar plate (10) having main surfaces (14, 16), a first plurality of elevations (18) and a first plurality of depressions (20), a second plurality of elevations and a second plurality of depressions, wherein a depression (20) has a counterpart elevation, wherein each elevation (18) and each depression (20) has a length (L), a width (B) and a height, wherein each elevation has, at its free end, as viewed in height direction, a tolerance compensation device which is set up to be elastically and / or plastically deformable such that the height of a corresponding elevation is reduced when a force acts on the free end of the elevation. The invention further relates to a stack comprising two such bipolar plates.

Description

[0001] Embossed bipolar plate

[0002] Description

[0003] The present invention relates to a bipolar plate for the construction of an electrochemical reactor.

[0004] Bipolar plates for electrochemical reactors are known from the prior art, manufactured using milling processes to create raised areas on the bipolar plates. These raised areas are intended to improve the flow characteristics of the fluid flowing along the bipolar plate. However, the manufacturing process for these bipolar plates is very complex, and therefore such bipolar plates are often not economically viable at present.

[0005] The object of the present invention is therefore to provide a bipolar plate which can be manufactured using an improved process and is thus, in particular, more cost-effective to produce compared to the prior art.

[0006] This problem is solved according to the present invention by a bipolar plate for the construction of an electrochemical reactor, wherein the bipolar plate comprises a plate-like base body having a first main surface and a second main surface which extend substantially parallel to each other, wherein a first plurality of protrusions and a first plurality of depressions are arranged on the first main surface of the base body, wherein a second plurality of protrusions and a second plurality of depressions are arranged on the second main surface of the base body, wherein, viewed in a normal direction to the first main surface and / or the second main surface, each depression of the first plurality of depressions on the first main surface is at least partially superimposed by a corresponding protrusion of the second plurality of protrusions on the second main surface, wherein,Viewed in a normal direction to the first principal surface and / or the second principal surface, each depression of the second plurality of depressions on the second principal surface is at least partially superimposed by a corresponding elevation of the first plurality of elevations on the first principal surface, wherein each elevation and each depression has a length measured along an axis that is substantially parallel to the first principal surface and / or the second principal surface, a width measured along an axis that is substantially parallel to the first principal surface and / or the second principal surface and substantially orthogonal to the longitudinal axis, and a height measured along an axis that is substantially normal to the first principal surface and / or the second principal surface, wherein each elevation has a tolerance compensation device at its free end viewed in the height direction.which is designed to be elastic and / or plastically deformable in such a way that the height of a corresponding protrusion is reduced when a force acts on the free end of the protrusion.

[0007] In this way, manufacturing tolerances of the bipolar plate, which affect the protrusions in such a way that the protrusions extend at different heights from a common main surface, can be compensated for by applying a predetermined force to the bipolar plate or to the protrusions of the bipolar plate with an electrode that is to be positioned on the bipolar plate. This causes those protrusions that extend further from the corresponding main surface than the other protrusions to be elastically and / or plastically compressed at their tolerance compensation device. Thus, the height of these protrusions approaches the height of the other protrusions, and the electrode can rest on a greater number of protrusions than would be the case without tolerance compensation devices.

[0008] Of course, it is conceivable that the electrode, in its mounted state, is pressed against the bipolar plate in such a way that a large proportion, for example at least 90%, in particular at least 95%, of the protrusions are elastically and / or plastically deformed.

[0009] Additionally, by compressing the higher elevations, a larger contact area for the electrode can be provided at each free end of the elevation (viewed in the vertical direction). This larger contact area, in turn, provides a larger joining surface for connecting, particularly welding, the electrode and the bipolar plate.

[0010] The bipolar plate can have at least one first fluid inlet, which is configured to direct fluid from an outside of the bipolar plate to the first main surface, at least one second fluid inlet, which is configured to direct fluid from an outside of the bipolar plate to the second main surface, at least one first fluid outlet, which is configured to direct fluid from the first main surface to an outside of the bipolar plate, and at least one second fluid outlet, which is configured to direct fluid from the second main surface to an outside of the bipolar plate.

[0011] Furthermore, the length of at least some of the elevations can be greater than their respective width.

[0012] Those elevations that are longer than they are wide can comprise a first elevation group and a second elevation group. The first elevation group can be located closer to the fluid inlet than the second elevation group.

[0013] A first main fluid flow direction can be defined by a straight axis running from the first fluid inlet to the first fluid outlet.

[0014] A second main fluid flow direction can be defined by a straight axis running from the second fluid inlet to the second fluid outlet.

[0015] The lengths of the elevations of the second elevation group can have an angle of 0° to 50°, in particular 0° to 45°, in particular 0° to 40°, advantageously 0° to 30°, relative to the first and / or second main fluid flow direction.

[0016] The lengths of the elevations of the first elevation group can have an angle of 40° to 90°, in particular 45° to 90°, in particular 50° to 90°, advantageously 60° to 90°, relative to the first and / or second main fluid flow direction.

[0017] Such a constructive design of the bipolar plate allows, firstly, the avoidance of a machining process and, secondly, enables the bipolar plate to be manufactured largely or even entirely by means of a forming process. Furthermore, the arrangement of the protrusions according to the invention ensures that the fluid introduced onto a respective main surface of the base body is distributed in a flow-optimized manner over the main surface of the base body, for example, essentially uniformly.

[0018] Furthermore, manufacturing the bipolar plate using such a forming process can lead to material savings compared to machining or additive manufacturing processes. This, in turn, can reduce manufacturing costs.

[0019] In particular, an angle of 0° signifies a substantially parallel alignment of the lengths of the projections with respect to the first and / or the second main fluid flow direction, and an angle of 90° signifies a substantially orthogonal alignment of the lengths of the projections with respect to the first and / or the second main fluid flow direction. It should also be noted that the angle specifications within the scope of the present invention are to be understood as absolute values. That is, an angle of, for example, 45° can describe both an angle of +45° and an angle of -45°. Thus, projections that are formed analogously and mirrored on both sides and relative to the respective main fluid flow direction can fall under the same feature with respect to a corresponding angle, even though their signs are different.

[0020] A further advantage of the present invention lies in the fact that, through the geometric design of the bipolar plate according to the invention, dead zones, i.e., for example, areas with a supersaturated electrolyte solution and / or an accumulation of produced gas, can be reduced or even completely avoided. This reduction / avoidance of dead zones can be achieved in particular by ensuring that the fluid flowing along the bipolar plate, due to the arrangement of the protrusions, exhibits flow characteristics with vector components both in the X-direction orthogonal to the first and / or second main fluid flow direction and in the Y-direction substantially parallel to the first and / or second main fluid flow direction.

[0021] The bipolar plate can be at least partially surrounded radially by a cell frame, which provides a border for the first and / or second main surface, such that the border forms a barrier in the radial direction of the bipolar plate for the fluid flowing along each main surface. The cell frame itself can also have a fluid inlet and / or a fluid outlet, so that the fluid inlet and / or fluid outlet of the bipolar plate need not necessarily be designed as an opening or recess in the bipolar plate, but can also be designed as a region of a respective main surface of the base body, which is located adjacent to the fluid inlet and / or fluid outlet of the cell frame.

[0022] In particular, the first collection group and / or the second collection group may include collections on both the first main surface and the second main surface. This may be the case, in particular, but not limited to, if the fluid inlet of the first main surface of the base body and the fluid inlet of the second main surface of the base body and / or the fluid outlet of the first main surface of the base body and the fluid outlet of the second main surface of the base body are located at substantially the same position.

[0023] Furthermore, it is also conceivable that a raised area is directly adjacent to a depression or even merges directly into it. Thus, a raised area of ​​the first main surface and a depression of the first main surface may not be separated from each other, but rather merge into one another, and / or a raised area of ​​the second main surface and a depression of the second main surface may not be separated from each other, but rather merge into one another.

[0024] The teaching presented herein regarding the bipolar plate according to the invention can also be applied, in a modified form, to a bipolar plate embossed on only one side, which has protrusions only on one of its main surfaces. Such a bipolar plate embossed on only one side can be used, in particular, as an end plate in a stack for the construction of an electrochemical reactor.

[0025] With further reference to such a stack for the construction of an electrochemical reactor, the bipolar plate according to the invention can provide the function of a spacer between the bipolar plate and the electrode. Thus, a fluid transport plane can be formed in a region between the bipolar plate and the electrode, in which fluid can flow along the respective main surface of the base body.

[0026] The tolerance compensation device of a given protrusion can be designed as a region arranged at the free end of the protrusion (considered in the vertical direction), which is curved in both the longitudinal and lateral directions of the protrusion, with the greatest height of the protrusion being located at its longitudinal and / or lateral center. Such a convexly curved surface of the protrusion can initially form a point contact with the electrode, whereby this point contact transitions into an increasingly larger surface contact as the electrode is pressed further onto the protrusion.

[0027] The tolerance compensation device of a given protrusion can, for example, also be designed as a projection arranged on that protrusion. This allows for the elastic and / or plastic deformation of only the projection itself when the electrode is pressed further onto the protrusion, rather than deforming the base body of the protrusion.

[0028] The projection, viewed in a cross-section which is essentially orthogonal to the vertical direction of the elevation, can be essentially circular.

[0029] The projection can also have a plateau at its free end, viewed in the vertical direction of the protrusion. This plateau has a surface that is essentially parallel to the main surface of the bipolar plate from which the protrusion extends. This allows for surface contact to be established right from the start of the contact between the electrode and the bipolar plate. This can be advantageous because surface contact with the electrode can be established even for protrusions that extend less far from the main surface than most of the other protrusions and are therefore less deformed when the electrode is applied.

[0030] In particular, the bipolar plate can be made of an electrically conductive material, especially metal and / or plastic. This can enable a current flow to be established between electrodes arranged on both sides of the bipolar plate. Particularly if the bipolar plate is made entirely of an electrically conductive material, it can be ensured that the current flow between the electrodes is homogeneous, both in the thickness direction of the bipolar plate and distributed across a respective main surface. Improved conductivity can, in turn, lead to more efficient use of the bipolar plate according to the invention or an associated electrochemical reactor due to lower energy consumption.

[0031] Advantageously, the bipolar plate can be monolithic. Since monolithic bipolar plates are made from a single piece of material, they are easier to manufacture than those made from multiple parts. A monolithic bipolar plate can also be more easily mounted in a stack. This can lead to lower manufacturing and assembly costs. Furthermore, a monolithic bipolar plate design can reduce electrical contact resistance between individual protrusions and the main surface compared to protrusions joined using a bonding process.

[0032] Furthermore, the bipolar plate can be designed without perforations in the area of ​​the first and second main surfaces. This can prevent fluid mixing between the fluid located on the first main surface and the fluid located on the second main surface, which can impair the efficiency, performance, and / or service life of the electrochemical reactor.

[0033] In particular, the first group of elevations can comprise a larger number of elevations than the second group. The first group of elevations can serve to distribute the fluid uniformly along the main surface, especially in a direction substantially orthogonal to the first main fluid flow direction. The effect of distributing the fluid along the main surface can be enhanced by a larger number of elevations in the first group. The second group of elevations can serve to align the fluid flow direction towards the fluid outlet. During the operation of an electrochemical reactor, hydrogen gas forms on one of the main surfaces.To prevent hydrogen gas from accumulating at the second sampling group and thus hindering its uniform discharge through the fluid outlet, it can be advantageous for the second sampling group to have fewer sampling points than the first. This is particularly relevant since hydrogen gas concentration typically increases towards the fluid outlet. Naturally, the above also applies to the oxygen side of an electrochemical reactor.

[0034] Advantageously, at least one raised area can be at least partially surrounded by a groove. The term "groove" here refers specifically to a depression that at least partially surrounds a raised area and is advantageously located directly adjacent to it. The groove's depression can thus extend into the main surface in a direction opposite to that of the raised area. Such a groove allows the associated raised area to be displaced relative to the main surface to a predetermined extent, particularly along a direction orthogonal to the main surface. This predetermined flexibility of the raised area relative to the main surface allows forces acting on the raised area to result in its displacement.This allows, for example, the compensation of manufacturing tolerances that might result in not all protrusions having exactly the same height relative to a main surface. This compensation, or by setting back the protrusions that extend further outwards, prevents an electrode positioned on these protrusions from being subjected to high point loads and potentially damaged as a result.

[0035] In possible embodiments of the present invention, the bipolar plate can have a plate thickness of 0.05 mm to 5 mm, particularly from 0.1 mm to 2 mm, advantageously from 0.5 mm to 1.5 mm. Bipolar plates with a small plate thickness result in an overall lighter and more compact electrochemical reactor. This is particularly important for applications where weight and size are critical. Furthermore, bipolar plates with a small plate thickness can lead to lower manufacturing costs due to the use of less material and simpler manufacturing processes.

[0036] Furthermore, the bipolar plate can be manufactured using a forming process, in particular by embossing and / or deep drawing and / or hydroforming. The use of a forming process can lead to material and time savings compared to machining processes and thus to lower manufacturing costs.

[0037] For example, the bipolar plate can have a circular, oval, or polygonal, and in particular rectangular, outer contour. The outer contour of the bipolar plate according to the invention can be adapted, in particular, to requirements arising from its use in a stack.

[0038] In the region of a median plane defined by the outer contour of the bipolar plate, particularly in the region of a plane of symmetry that symmetrically divides the outer contour of the bipolar plate, a formation of protrusions may be arranged, the formation of protrusions extending essentially in a direction parallel to the median plane. Particularly in the case where the electrode arranged on the bipolar plate is multi-part, especially two-part with two halves, these protrusions may serve to provide a bearing surface for the electrode or an electrode part even in a region distant from the outer contour of the bipolar plate.

[0039] The formation of protrusions can be arranged symmetrically with respect to the central plane, in particular the plane of symmetry. This allows, in particular, the support of essentially symmetrical electrode components, for example, two electrode halves.

[0040] The median plane, in particular the plane of symmetry, can extend from the first or second fluid inlet to the first or second fluid outlet.

[0041] The bipolar plate can further comprise an additional formation of protrusions, which are arranged, at least in sections, substantially following the outer contour of the bipolar plate. For example, if the outer contour of the bipolar plate is substantially circular, a further formation of protrusions, also substantially circular or ring-shaped, can be arranged, spaced radially inward from the outer contour and following it. In this way, a correspondingly substantially circular electrode can also have a bearing surface at its radially outer edge provided by this further formation of protrusions. This can, of course, be applied analogously to other outer contours.

[0042] For example, the elevations of the outer formation may be higher than the elevations of the formation itself.

[0043] Furthermore, an electrode can only be metallurgically connected to the bipolar plate at the elevations of the further formation.

[0044] In particular, the first main surface of the bipolar plate can form an anode side of the electrochemical reactor and the second main surface of the bipolar plate can form a cathode side of the electrochemical reactor.

[0045] The present invention may further relate to a joined functional assembly comprising a bipolar plate according to the invention and two electrodes, wherein an electrode is arranged on each main surface of the bipolar plate. The bipolar plate and the respective electrode may be firmly joined together, for example by welding, in the region of at least one selected contact point, and in particular in the region of all contact points.

[0046] In a further development of the invention, it is conceivable that at least one projection of the first plurality of projections on the first main surface has a height that differs from the height of at least one other projection of the first plurality of projections on the first main surface, and / or that at least one projection of the second plurality of projections on the second main surface has a height that differs from the height of at least one other projection of the second plurality of projections on the second main surface. In this way, for example, it can be achieved that only a limited number of projections, in particular those with a greater height, are in contact with an associated electrode.The remaining protrusions can contribute to flow optimization at the bipolar plate or at the respective main surface of the bipolar plate, but the area of ​​the electrode adjacent to these (smaller) protrusions can be used for contact with the electrolyte and thus for gas generation. It is conceivable that protrusions of the second group do not have the same height as protrusions of the first group.

[0047] Furthermore, at least one elevation of the first plurality of elevations on the first main surface can have a height that differs from the height of at least one elevation of the second plurality of elevations on the second main surface, wherein, in particular, the height of the at least one elevation of the first plurality of elevations on the first main surface can differ by a factor of 0.5 to 2.0, advantageously by 1.1 to 1.5, and in particular be higher, than the height of the at least one elevation of the second plurality of elevations on the second main surface. As already described above, a predetermined and desired property for the transport of fluid flowing on this main surface, for example a liquid-gas mixture, can be achieved by a suitable arrangement of elevations of different heights on a respective main surface.

[0048] The bipolar plate can have welding surfaces designed to come into contact with a respective section of an electrode arranged on the bipolar plate, enabling them to be joined together. For example, such welding surfaces can be arranged on a main surface of the bipolar plate, designed to come into contact with sections projecting from the electrode, in order to be joined, for example, by a metallurgical bond.

[0049] Furthermore, it should be noted that at least one elevation of the bipolar plate can have a shape in which the longitudinal flanks, that is, the lateral and longitudinally extending areas of a given elevation adjacent to its main surface, can be convex. Depending on the degree of convexity of the longitudinal flanks of an elevation, the elevation can thus have a substantially oval, pointed oval, or elliptical basic shape. Alternatively or in addition to the convex longitudinal flank, a transition, in particular a rounding, from a longitudinal flank to a top surface of the elevation (that is, its free end), viewed along the longitudinal direction, can also vary. For example, the transition in the region of the longitudinal center of the elevation, in particular the rounding, can be smaller than at the longitudinal ends of the elevation.This allows the width of the top of the protrusion to be increased, thus providing a larger support surface or welding area for the electrode.

[0050] For the sake of completeness, it should be mentioned that the bipolar plate may, of course, have further elevations and / or depressions in addition to those described herein, which may be arranged and / or formed as desired.

[0051] According to a further aspect of the present invention, the problem described at the outset is solved by a stack for constructing an electrochemical reactor, comprising at least one first and at least one second bipolar plate according to one of the preceding claims. It should be noted at this point that all features, effects, and advantages described with regard to the bipolar plate according to the invention can also be applied to a stack according to the invention, and vice versa.

[0052] The stack can further comprise at least one electrode which is connected, and in particular welded, to the bipolar plate at at least one tolerance compensation device, in particular at at least one plateau. Thus, at least one contact surface between the electrode and the bipolar plate can also serve as a weld surface.

[0053] Alternatively or additionally, the electrode can have at least one projection which is connected to the first or second bipolar plate, in particular welded to at least one welding surface.

[0054] Furthermore, the at least one projection of the at least one electrode can comprise a formed section which is formed by a forming process downstream of the primary forming process, wherein the at least one electrode is connected to the first or second bipolar plate in the area of ​​the formed section of the at least one projection, wherein in particular a welding surface is arranged on the formed section of the at least one projection of the electrode, which is designed to be metallurgically joined to the first or second bipolar plate using a welding process.

[0055] A "primary forming process," particularly in the context of electrode manufacturing from metal, can be understood as a process in which a basic planar shape of the electrode is formed from a starting material, such as a sheet of metal, for example, by cutting or stamping. A "forming process," on the other hand, can be understood as a machining process in which a solid material is deliberately brought into a specific shape by the application of force, particularly without removing or adding material.

[0056] A "material-bonded connection" can refer in particular to a process in which materials are joined together. This can be achieved, for example, by mixing or joining the materials at a connection point (for example, the weld surface) in such a way that an essentially continuous material structure is created.

[0057] The at least one electrode can, in particular, comprise a plate-like base body having a first principal surface and a second principal surface which extend substantially parallel to each other. The first principal surface of the at least one electrode can, for example, be a principal surface which, in the state of the electrode being arranged on the bipolar plate, faces away from the bipolar plate, and the second principal surface of the at least one electrode can correspondingly be the principal surface which faces the bipolar plate.

[0058] The at least one projection can comprise a first section in addition to the transformed section. This first section can, for example, extend from an edge of the electrode in a plane that is essentially parallel, and in particular flush, with the first and / or second principal surface of the electrode. This means that the first section of the at least one projection can have or extend a first principal surface and a second principal surface.

[0059] In the area of ​​the formed section of the at least one projection, the first main surface of the at least one projection can face the bipolar plate, and the second main surface of the at least one projection can face away from the bipolar plate. Thus, the formed section of the at least one projection can be rotated by 180° relative to the first and / or second main surface of the bipolar plate and / or the electrode during the forming process. This can be achieved, for example, by two 90° bends spaced apart in the same bending direction.

[0060] By providing a reshaped section of the at least one projection of the at least one electrode, it can be achieved that additional or alternative contact surfaces are created between the at least one electrode and the bipolar plate, which are, for example, designed to form welding surfaces in order to connect the at least one electrode to the bipolar plate, in addition to or as an alternative to a connection at at least one tolerance compensation device, on a main surface of the bipolar plate.

[0061] Furthermore, the at least one projection of the at least one electrode can comprise a recess, wherein the recess is arranged such that the welding surface of the deformed section of the at least one projection is accessible for a welding process of the electrode with the first or second bipolar plate, wherein, in particular, the recess, viewed along a Z-direction which is orthogonal to a main surface of the first or second bipolar plate, is arranged to at least partially cover the associated welding surface.

[0062] The recess of the at least one projection can preferably be arranged on the first section of the at least one projection. The recess of the at least one projection allows the welding surface of the at least one projection to be accessed in a straight line along a Z-direction for the welding process, in particular for a laser beam and / or a corresponding tool. Particularly in the case where the electrode is connected to the bipolar plate via projections extending from the electrode, and especially welded, but not limited to this, the electrode can be separated from the bipolar plate at the end of its service life, for example by cutting it off, and the bipolar plate can be recycled into a new electrolyzer.

[0063] It should be noted that, for the sake of simplicity, the present description predominantly discloses an exemplary joining method, such as welding, with regard to the connection between the electrode and the bipolar plate, although any alternative joining method, such as mechanical joining methods (e.g., pressure joining or clinching), is equally conceivable.

[0064] Furthermore, the at least one electrode can be an anode, wherein the anode comprises a plate-like base body having a first main surface and a second main surface which extend substantially parallel to each other, wherein in particular the first main surface has a surface which is electrically insulating, preferably by means of a catalytic coating, and the second main surface has a surface which is electrically insulating, preferably by means of a thermal coating.

[0065] The thermal coating can, for example, be an oxide layer.

[0066] For example, the two bipolar plates in the stack can be arranged in a mirrored position relative to each other.

[0067] In this arrangement, a first bipolar plate can be positioned relative to a second bipolar plate in the stack such that at least one protrusion, in particular all protrusions, of the first bipolar plate is opposite a respective protrusion of the second bipolar plate, viewed in a normal direction to the first principal surface and / or the second principal surface of the first bipolar plate. "Opposite" here can further mean that the at least one protrusion, in particular all protrusions, of the first bipolar plate and a respective protrusion of the second bipolar plate point towards each other, viewed in a normal direction to the first principal surface and / or the second principal surface of the first bipolar plate.By arranging the first and second bipolar plates in a stack of electrochemical reactors according to the invention in a mirror-symmetrical manner, such that the protrusions face each other, it is possible to transfer a load acting on one of the bipolar plates evenly to the other bipolar plate via an electrode-separator unit arranged between the two bipolar plates. In this way, damage to the electrode-separator unit can be prevented. Furthermore, because the first and second bipolar plates are provided with protrusions, an electrode-separator unit can be used in which the electrodes themselves are free of protrusions. Thus, a single electrode can be used for the production of a given gas across its entire surface.

[0068] The bipolar plate can be surrounded by electrolyte on both sides. In particular, the use of the bipolar plate with an electrolyte having a pH value in the range of 7 to 14, especially in the range of 12 to 14, is conceivable.

[0069] Advantageously, the first bipolar plate and the second bipolar plate can be configured according to the bipolar plate according to the invention. Thus, the first bipolar plate and the second bipolar plate can also feature the flow-optimized arrangement of the bipolar plate according to the invention, to which explicit reference is made hereby made in the above description.According to one aspect, which can be seen in combination with the bipolar plate according to the invention described herein or the stack comprising such a bipolar plate described herein, but which can also be applied independently in general to bipolar plates of any design, a bipolar plate can have a structural sealing area which has at least one sealing surface projecting from the first main surface and / or from the second main surface of the bipolar plate, which is configured to provide a fluidic seal from a radially inner side of the bipolar plate along the first main surface and / or along the second main surfaces to the radial outside in a state in which the bipolar plate is connected to a component adjacent thereto.

[0070] In this context, it should be noted that the term "radial" does not necessarily refer to a circular outer contour of the bipolar plate with a constant radius, but can also be understood in the context of arbitrarily shaped outer contours. Rather, the term "radial" can be understood here as a directional characteristic, describing the direction parallel to the corresponding main surface of the bipolar plate – in contrast to the circumferential direction or the thickness direction of the bipolar plate.

[0071] The structural sealing area can be arranged adjacent to an outer contour of the bipolar plate.

[0072] The structural sealing area can in particular comprise two sealing surfaces projecting from the first main surface and two sealing surfaces projecting from the second main surface.

[0073] The sealing surfaces can be arranged such that, viewed radially along the bipolar plate, they are spaced apart from each other. That is, the sealing surfaces can be arranged such that, viewed along the thickness of the bipolar plate, they do not overlap.

[0074] The structural sealing area on the bipolar plate can be configured such that it completely surrounds the protrusions arranged on the first main surface of the bipolar plate and / or the protrusions arranged on the second main surface of the bipolar plate. Thus, the area of ​​the bipolar plate located within the structural sealing area can be fluidically sealed to the outside when mounted in the stack.

[0075] The structural sealing area can be viewed in a cross-section whose cutting plane runs essentially in a radial direction and orthogonally to the first main surface and / or to the second main surface of the bipolar plate, and can be formed in a wave-like shape.

[0076] The structural sealing area can be formed by a forming process such as bending, embossing, upsetting, forging or similar.

[0077] In particular, the wall thickness of the bipolar plate in the area of ​​the structural sealing section can be essentially the same as the wall thickness of the rest of the bipolar plate. If the bipolar plate has a coating that differs in the structural sealing area compared to the rest of the bipolar plate, such a coating can be disregarded for the aforementioned comparison of wall thicknesses.

[0078] A sealing surface projecting from the first main surface of the bipolar plate can, viewed in the thickness direction of the bipolar plate, be arranged to substantially superimpose a recess on the second main surface of the bipolar plate and / or a sealing surface projecting from the second main surface of the bipolar plate can, viewed in the thickness direction of the bipolar plate, be arranged to substantially superimpose a recess on the first main surface of the bipolar plate.

[0079] A sealing surface and / or a recess of the structural sealing area can protrude from the respective main surface or be recessed into the respective main surface of the bipolar plate by an amount ranging from 0.2 times the wall thickness of the bipolar plate to 5 times the wall thickness of the bipolar plate, in particular from 0.5 times the wall thickness of the bipolar plate to 3 times the wall thickness of the bipolar plate.

[0080] Furthermore, it is conceivable that sealing surfaces on the same side of the bipolar plate, that is, on the same main surface of the bipolar plate, protrude by different dimensions. An analogous principle can also be applied to the recess dimensions of depressions in the structural sealing surface.

[0081] At least one sealing surface of the structural sealing area can be curved, with the radius of curvature being particularly in a range of 0.5 mm to 5 mm, particularly in a range of 0.8 mm to 3 mm, advantageously in a range of 0.8 mm to 2 mm, for example 0.65 mm, 0.8 mm, 0.9 mm, 1 mm, 1.5 mm or 2.5 mm.

[0082] The distance between two sealing surfaces, viewed in the radial direction of the bipolar plate, can be in a range of 2 mm to 10 mm, in particular from 3 mm to 6 mm, advantageously in a range of 4 mm to 5 mm.

[0083] The ratio of the distance between two sealing surfaces, viewed in a radial direction of the bipolar plate, to the extent of a sealing surface protruding from an associated main surface of the bipolar plate can be in a range of 0.5 to 10.0, in particular from 0.6 to 8.0, advantageously from 0.8 to 7.0.

[0084] The ratio of the extent of the protrusion of a sealing surface from an associated main surface of the bipolar plate to a wall thickness of the bipolar plate can be in a range of 0.2 to 25.0, in particular from 0.3 to 15.0, advantageously from 0.3 to 8.0.

[0085] In particular, if the structural sealing area has a wave-like cross-section, an angle between a region arranged radially inside the bipolar plate adjacent to the structural sealing area, in particular between the first main surface or the second main surface of the bipolar plate, and an adjacent wave flank leading to a wave crest or trough of the structural sealing area, in particular to a tangent of the wave flank passing through the inflection point of the wave flank, may lie in a range between 15 degrees and 50 degrees, in particular in a range between 25 degrees and 45 degrees, advantageously in a range between 30 degrees and 40 degrees.

[0086] Advantageously, the extent of a sealing surface's projection from a corresponding main surface of the bipolar plate, viewed along the circumferential path of the structural sealing surface—that is, optionally along a path around the protrusions arranged on this main surface of the bipolar plate—can be varied. For example, the projection of the sealing surface from the corresponding main surface can alternately increase and decrease such that the circumferential path of the sealing surface is essentially undulating. It can be provided that the extent of the sealing surface's projection from the corresponding main surface is always greater than zero. The bipolar plate can include at least one further structural sealing area, which is configured to define a radially outwardly fluidically sealed region within its interior.

[0087] It may be provided that the structural sealing area and / or at least one further structural sealing area has a fluid passage in which the sealing surfaces protrude from the corresponding main surface by a maximum of 50% of the extent of the protrusion of the sealing surfaces in the remaining area of ​​the structural sealing area or the further structural sealing area, in particular in which the sealing surfaces do not protrude from the corresponding main surface, so that fluid can be exchanged via the fluid passage between an inner area and an outer area defined by the corresponding structural sealing area or the further structural sealing area, even when the bipolar plate is mounted.The provision of at least one fluid passage at the structural sealing area and / or at least one further structural sealing area, in the context of the statements made above that a structural sealing area can create a fluidic seal, is to be understood as meaning that a structural sealing area forms this fluidic seal "otherwise", that is, "with the exception of the fluid passage" or "considered at a respective point of the structural sealing area".

[0088] Advantageously, a structural sealing area can be designed to be electrically conductive, at least in sections.

[0089] The structural sealing area can be designed to resemble a cell frame in such a way that the cell frame can be centered relative to the bipolar plate via the structural sealing area of ​​the bipolar plate. For this purpose, structural elements on the cell frame, such as a projection or an inner circumference, can be designed to match the structure of the structural sealing area of ​​the bipolar plate.

[0090] The present invention will now be explained in greater detail with reference to two exemplary embodiments and the accompanying drawings. It illustrates:

[0091] Figure 1 shows a top view of a bipolar plate according to the invention;

[0092] Figure 2 shows a side cross-sectional view of a section of the bipolar plate from Figure 1 along the line AA shown in Figure 1;

[0093] Figure 3 shows a perspective view of a second embodiment of a bipolar plate according to the invention;

[0094] Figure 4 shows a side cross-sectional view of a section of a stack according to the invention consisting of a first and a second bipolar plate;

[0095] Figure 5 shows a perspective view of a design form of an elevation;

[0096] Figure 6 shows a side view of the elevation from Figure 5;

[0097] Figure 7 shows a perspective view of another design form of an elevation;

[0098] Figure 8 shows a side view of the elevation from Figure 7;

[0099] Figure 9 shows further possible forms of elevations;

[0100] Figure 10 shows a perspective view of another embodiment of a bipolar plate according to the invention;

[0101] Figure 11 shows a perspective view of an embodiment of a stack according to the invention;

[0102] Figure 12 shows a side cross-sectional view of the stack from Figure 11 along the line X1-X1 shown in Figure 11; and

[0103] Figure 13 is a perspective view of the cross-section from Figure 11.

[0104] In Figure 1, the bipolar plate according to the invention is generally designated by reference numeral 10. The bipolar plate comprises a round, plate-shaped base body 12, which has a first main surface 14 and a second main surface 16 (see Figure 2). The first main surface 14 and the second main surface 16 extend parallel to each other.

[0105] On the first main surface 14 of the base body 10, a first plurality of protrusions 18 and a first plurality of depressions 20 are arranged. On the second main surface 16 of the base body 10, a second plurality of protrusions 22 and a second plurality of depressions 24 are arranged (see Figure 2). In the embodiment shown here, particularly with reference to Figure 2, a protrusion 18 defines a depression 24 on its inner side, which is arranged on the second main surface 16. Analogously, a protrusion 22 defines a depression 20 on its inner side, which is arranged on the second main surface 16. This is because the bipolar plate 10 shown here is manufactured using an embossing process, such that pressing material into the first main surface 14 to create a depression 20 simultaneously creates a protrusion 22 on the second main surface 16.Figures 1 and 2 together show that some (in the embodiment shown all) elevations and depressions have a length L, a width B and a height H.

[0106] In the special embodiment shown in Figures 1, 2 and 4, a depression 20 and a protrusion 18 on the first main surface 14 and a protrusion 22 and a depression 24 on the second main surface 16 are formed directly adjacent to each other as a pair 26.

[0107] The bipolar plate 10 further comprises a fluid inlet 28 and a fluid outlet 30, which is positioned diametrically opposite the fluid inlet 24 with respect to the base body 12. The fluid inlet 28 and the fluid outlet 30 are indicated here by an oval ring. The fluid inlet 28 and the fluid outlet 30 can also be a region of the respective main surface 14, 16, into which a fluid passage opens through a cell frame (not shown) that surrounds the base body 12 of the bipolar plate 10. In particular, the first main surface 14 can have a fluid inlet 28 and a fluid outlet 30, and the second main surface 16 can have a separate fluid inlet (not shown) and a separate fluid outlet (not shown).

[0108] A connecting line from the fluid inlet 28 to the fluid outlet 30 forms a main fluid flow direction X, which coincides with the section line A-A in Figure 1 and is therefore only indicated by the arrow X attached to the section line AA. If a second fluid inlet and a second fluid outlet are formed on the main surface 16 facing away from the main surface 16 in Figure 1, the main fluid flow direction X can be considered the first main fluid flow direction X, and the main fluid flow direction of the connection between the second fluid inlet and the second fluid outlet on the second main surface 16 can be considered the second main fluid flow direction.In Figure 1, some of the elevations 18 on the first main surface 14 are grouped into a first elevation group 32 and some of the elevations 18 on the first main surface 14 are grouped into a second elevation group 34, with the first elevation group 32 being located closer to the fluid inlet 24 than the second elevation group 34.

[0109] It can be seen that the lengths of the protrusions 18 of the first protrusion group 32 are arranged at an angle to the main fluid flow direction X such that the angle α formed between them is 45° or more, whereas the lengths of the protrusions 18 of the second protrusion group 34 are arranged at an angle to the main fluid flow direction X such that the angle α formed between them is less than 45° (here even 0°). The first protrusion group 32 can thus serve to distribute the fluid over the respective main surface 14. The second protrusion group 34 can serve to direct and guide the fluid towards the fluid outlet 26.

[0110] Figure 3 shows a second embodiment of a bipolar plate according to the invention in a perspective view, which is designated by reference numeral 110. In the second embodiment of the bipolar plate 110, features analogous to those of the first embodiment of the bipolar plate 10 are designated with analogous reference numerals, but increased by 100. Therefore, the following discussion will focus primarily on the differences between the second embodiment of the bipolar plate 110 and the first embodiment of the bipolar plate 10.

[0111] In the embodiment of the bipolar plate 110 shown in Figure 3, analogous to the protrusions 18, 22 and depressions 20, 24, protrusions 118 and depressions 120 are formed on the first main surface 114. However, the protrusions 118 and depressions 120 on the first main surface 114 are spaced apart from each other, that is, they are not formed as a pair 26. As already described with reference to the bipolar plate 10, the depressions 120 also result in protrusions on the second main surface, which is opposite the first main surface 114 and faces away from it in Figure 3. Likewise, the protrusions 118 form depressions on their inner side on the second main surface.

[0112] In contrast to the first embodiment of the bipolar plate 10, the second embodiment of the bipolar plate 110 has grooves 136 which completely surround the respective protrusions 118. That is, looking from the main surface 114 to the respective protrusion 118, a depression formed by the groove is located in front of the protrusion. This allows a certain degree of displacement of the protrusion 118 in the vertical direction H.

[0113] Figure 4 shows a side cross-sectional view of an embodiment of a section of a stack 38 according to the invention. The stack 38 comprises a first bipolar plate 10a and a second bipolar plate 10b, both of which are configured according to the bipolar plate 10 according to the invention, but mirrored relative to each other. The first bipolar plate 10a is arranged in the stack 38 relative to the second bipolar plate 10b such that each projection 18 of the first bipolar plate 10a is opposite a projection 18 of the second bipolar plate 10b, viewed in the vertical direction H of a respective projection 18 or in a normal direction to the main surfaces 14, 16 (see Figure 2) of the first bipolar plate 10a and / or the second bipolar plate 10b. This arrangement of the first bipolar plate 10a and the second bipolar plate 10b results in a plane of symmetry S, which is located centrally between the two bipolar plates 10a and 10b.

[0114] Figure 4 also shows a separator 40, a first electrode 42, and a second electrode 44. The separator 40 is arranged centrally between the two bipolar plates 10a and 10b (on the mirror plane S). The first electrode 42 is located on one side of the separator 40, and the second electrode 44 is located on the other side of the separator 40, thus forming an electrode-separator unit.

[0115] For the sake of completeness, it should be explicitly mentioned that the stack 38 according to the invention can also be formed using two mutually mirrored bipolar plates 110.

[0116] Figure 5 shows an example of a possible embodiment of a raised feature, which is designated here by reference numeral 46. As already explained with reference to the previously described raised features 18 and 22, the raised feature 46 has a longitudinal extension L, a lateral extension B, and a vertical extension H (see Figure 6). The raised feature 46 shown in Figures 5 and 6 incorporates a tolerance compensation device in that a top surface 50 of the raised feature 46 is curved, here convex, when viewed in the longitudinal direction L. If an electrode 52 (see Figure 9) is now placed on the top surface 50 of the raised feature 46 and pressed down with a predetermined force, the top surface 50 of the raised feature 46 can be deformed from the curved initial shape shown in Figure 6 towards a straight extension in the longitudinal direction L (at least in a longitudinal central region of the raised feature 46).In this way, the height of the protrusions 46, which are higher than other protrusions of the bipolar plate 10, 110 due to manufacturing reasons, can be reduced so that the electrode 52 can rest on a large part, in particular all, of the protrusions of the bipolar plate.

[0117] To provide the electrode with a sufficient contact area right from the start of contact with the projection 46, a transition area 54 between the upper surface 50 and a longitudinal flank 56 of the projection 46 is designed such that it varies from one longitudinal end of the projection 46 to the other. In the embodiment shown here, the transition area 54 is formed by a rounding which has a smaller extent in the width direction B across the projection 46 in the region of the longitudinal center of the projection 46 than at the longitudinal ends of the projection 46. In this way, the surface area 50 of the projection 46, or rather its width extent, can be increased in the region of the longitudinal center of the projection 46.

[0118] Figures 7 and 8 show another embodiment of a projection 58. The projection 58 also has a tolerance compensation device, which is designated by reference numeral 60. Here, the tolerance compensation device 60 is designed as a projection 62 extending away from the upper surface 64 of the projection 58.

[0119] In this case, a plateau 66 is formed at the free end of the projection 62, viewed in the vertical direction H, which forms a surface essentially parallel to the main surface 14 of the bipolar plate 10.

[0120] If an electrode 52 is now placed on the projection 62, a surface contact between the bipolar plate 10 and the electrode 52 is already formed via the plateau 66 at the beginning of such an arrangement. If the electrode 52 is now pressed onto the bipolar plate 10 with the predetermined force described above, the extent of the projection 62 in the vertical direction H can be reduced by deformation of the projection 62 in order to achieve tolerance compensation with the other projections of the bipolar plate. It is conceivable that only the projection 62 deforms during this tolerance compensation, but not the rest of the base body of the projection 58.

[0121] Figure 9 shows further possible embodiments 68, 70, 72 and 74 of elevations. It can be seen that the elevation 68 has a longitudinal flank 56 extending essentially straight in the longitudinal direction L, with the longitudinal flank 56 transitioning at its longitudinal ends into a respective end face 76 forming a rounded edge 78.

[0122] In elevations 70 and 72, the rounding 78 is enlarged to such an extent that the longitudinal flank 56, which extends essentially straight in the longitudinal direction L, has been reduced to the longitudinal central area of ​​elevation 70, 72.

[0123] In the case of the elevation 74, the rounding 78 is now enlarged to such an extent that the rounding 78 from one end face 76 transitions directly into the rounding 78 at the other end face 76 of the elevation 74. The elevation 74 can thus be free of a longitudinal flank 56 extending essentially straight in the longitudinal direction L.

[0124] Figure 10 shows that it is conceivable for the electrode 52 to comprise two halves 52a and 52b. The two electrode halves 52a, 52b are placed on a bipolar plate 210 such that they abut each other in the center. In order to reliably support each of the two electrode halves 52a, 52b on the bipolar plate 210, the bipolar plate 210 has a formation 80 of protrusions, which are equidistant from a central plane M of the bipolar plate 210.

[0125] Furthermore, the bipolar plate 210 has a further formation 82 of protrusions (three of which are designated by reference numeral 82 in Figure 10 as examples) to support the electrode halves 52a, 52b at their outer edges. Since the electrode 52 has an outer contour essentially analogous to that of the bipolar plate 210 (but smaller by a predetermined amount), the further formation 82 of protrusions is arranged such that the sequence of protrusions of the further formation 82 essentially follows the outer contour of the bipolar plate 210. Of course, the bipolar plate 210 can have further protrusions and / or depressions, which are not shown here and which can be formed according to the protrusions and / or depressions described herein and / or be formed arbitrarily.

[0126] Figure 11 shows a perspective view of an alternative embodiment of an electrode, which is provided with reference numeral 352 and is designed to be connected to a bipolar plate, here the bipolar plate 310a, which includes protrusions 318.

[0127] The electrode 352 can, in particular, comprise a plate-like base body having a first principal surface and a second principal surface which extend substantially parallel to each other. The first principal surface of the electrode 352 can, for example, be a principal surface facing away from the bipolar plate 310a, and the second principal surface of the at least one electrode 352 can be the principal surface facing the bipolar plate 310a.

[0128] The electrode 352 comprises a plurality of projections 390, each of which includes a first section 392a and a modified section 392b. The first section 392a can extend from an edge of the electrode 352 in a plane that is essentially parallel to the first and / or second principal surface of the electrode 352. This means that the first section 392a of each projection 390 has a first principal surface and a second principal surface which, with respect to their orientation relative to the bipolar plate 310a, correspond to the first and second principal surfaces of the electrode 352.

[0129] The respective formed section 392b of the projections 390 can also have a first and a second main surface, which correspond to a continuation of the first and second main surfaces of the first section of the respective projections, wherein in the region of the formed section 392b the first and second main surfaces of the respective projections 390 are rotated by 180° relative to the respective main surface of the electrode, that is, here the first main surface faces the bipolar plate 310a and the second main surface faces away from the bipolar plate 310a. This makes it possible that, in addition to the contact surfaces of the electrode 352 and the bipolar plate 310a on the elevations 318 of the bipolar plate 310a, further contact surfaces between the electrode 352 and the bipolar plate 310a can be realized, which enable an alternative or additional weld connection at a corresponding weld surface 394 of the respective projections 390.

[0130] In order to make the respective welding surfaces 394 accessible for a welding process, the projections 390 each include a recess 396, which is arranged here on the respective first section 392a of the respective projections 390.

[0131] As can be seen from Figure 12, which shows a side cross-sectional view of the stack 338 from Figure 11 along the line X11-X11 shown in Figure 11, a respective recess 396 of the projections 390 can be arranged superimposed on the formed section 392b of the respective projections 390 with respect to a Z-direction, wherein the Z-direction here extends orthogonally to the first and / or second main surface of the electrode 352. Thus, straight-line access for a welding process to a respective welding surface 394 of the projections 390 is enabled.

[0132] To further illustrate the arrangement of electrode 352 on the bipolar plate 310a, Figure 13 also shows a perspective view of the cross-section along line X11-X11 shown in Figure 11. Here it can be seen that contact can occur between at least one protrusion 318 and electrode 352, but this is not mandatory.

Claims

- 35 - Claims 1. Bipolar plate (10, 110, 210) for the construction of an electrochemical reactor, wherein the bipolar plate (10, 110, 210) comprises a plate-like base body (12) having a first main surface (14, 114) and a second main surface (16) extending substantially parallel to each other, wherein a first plurality of protrusions (18, 118) and a first plurality of depressions (20, 120) are arranged on the first main surface (14, 114) of the base body (12), wherein a second plurality of protrusions (22) and a second plurality of depressions (24) are arranged on the second main surface (16) of the base body (12), wherein, viewed in a normal direction (H) to the first main surface (14, 114) and / or the second main surface (16), a respective depression (20, 120) of the first plurality of depressions (20, 120) on the first main surface (14,114) is at least partially superimposed by an associated elevation (22) of the second plurality of elevations (22) on the second principal surface (16), wherein, viewed in a normal direction (H) to the first principal surface (14, 114) and / or the second principal surface (16), each depression (24) of the second plurality of depressions (24) on the second principal surface (16) is at least partially superimposed by an associated elevation (18) of the first plurality of elevations (18) on the first principal surface (14, 114), wherein each elevation (18, 118; 22) and each depression (20, 120; 24) has a length (L) measured along an axis substantially parallel to the first principal surface (14, 114) and / or the second principal surface (16), and a width (B) measured along an axis substantially parallel to the first principal surface (14, 114, 114) and / or to, - 36 - the second principal surface (16) is substantially parallel and substantially orthogonal to the longitudinal axis (L), and has a height (H) which is measured along an axis which is substantially normal to the first principal surface (14, 114) and / or to the second principal surface (16), wherein each projection has at its free end, as viewed in the vertical direction, a tolerance compensation device which is configured to be elastically and / or plastically deformable such that the height of a corresponding projection is reduced when a force is applied to the free end of the projection.

2. Bipolar plate (10, 110, 210) according to the preceding claim, characterized in that the tolerance compensation device of a respective projection (46) is designed as a region arranged at the free end considered in the height direction of the projection (46), which is curved both in the longitudinal direction (L) and in the width direction (B) of the projection (46), wherein in particular a maximum height (H) of the projection (46) is arranged at a longitudinal center and / or width center of the projection (46), or that the tolerance compensation device (60) of a respective projection (58) is designed as a projection (62) which is arranged on a respective projection (58), wherein in particular the projection (62), considered in a cross-section which is substantially orthogonal to the height direction (H) of the projection (58), is substantially circular,wherein in particular the projection (62) at its free end, viewed in the vertical direction (H) of the elevation (58), has a plateau (66) which has a surface running essentially parallel to the associated main surface (14, 16) of the bipolar plate (10, 110, 210) from which the elevation (58) extends.

3. Bipolar plate (10, 110, 210) according to one of the preceding claims, characterized in that the bipolar plate (10, 110, 210) is made of is made of an electrically conductive material, in particular metal and / or plastic, and / or that the bipolar plate (10, 110, 210) is monolithic, and / or that the bipolar plate (10, 110, 210) is free of perforations in the area of ​​the first main surface (14, 114) and the second main surface (16), and / or that the bipolar plate (10, 110, 210) has a plate thickness of 0.05 mm to 5 mm, in particular of 0.1 mm to 2 mm, advantageously of 0.5 mm to 1.5 mm, and / or that the bipolar plate (10, 110, 210) is manufactured using a forming process, in particular by embossing and / or deep drawing and / or hydroforming.

4. Bipolar plate (10, 110, 210) according to one of the preceding claims, characterized in that the bipolar plate (10, 110, 210) has a circular or oval or polygonal, in particular rectangular, outer contour.

5. Bipolar plate (10, 110, 210) according to the preceding claim, characterized in that in the region of a median plane (M) defined by the outer contour of the bipolar plate (10, 110, 210), in particular in the region of a plane of symmetry which symmetrically divides the outer contour of the bipolar plate (10, 110, 210), a formation (80) of protrusions is arranged, wherein the formation (80) of protrusions extends substantially in a direction parallel to the median plane (M).

6. Bipolar plate (10, 110, 210) according to the preceding claim, characterized in that the formation (80) is arranged at equal intervals, and in particular symmetrically, on elevations to the median plane (M), in particular the plane of symmetry.

7. Bipolar plate (10, 110, 210) according to claim 12 or 13, characterized in that the bipolar plate (10, 110, 210) has at least one first fluid inlet (28) configured to direct fluid from an outer surface of the bipolar plate (10, 110, 210) to the first main surface (14, 114), at least one second fluid inlet configured to direct fluid from an outer surface of the bipolar plate (10, 110, 210) to the second main surface (16), at least one first fluid outlet (30) configured to direct fluid from the first main surface (14, 114) to an outer surface of the bipolar plate (10, 110, 210), and at least one second fluid outlet configured to direct fluid from the second main surface (16) to an outer surface of the bipolar plate (10, 110, 210). 110, 210) to guide, whereby the middle plane (M), in particular the plane of symmetry,extends from the first (28) or the second fluid inlet to the first (30) or the second fluid outlet.

8. Bipolar plate (10, 110, 210) according to one of claims 11 to 14, characterized in that the bipolar plate (10, 110, 210) comprises a further formation (82) of protrusions which is arranged at least sectionally following the outer contour of the bipolar plate (10, 110, 210) substantially.

9. Bipolar plate (10, 110, 210) according to one of the preceding claims, characterized in that at least one elevation (18, 118) of the first plurality of elevations (18, 118) on the first main surface (14, 114) has a height (H) which differs from a height (H) of at least one other elevation (18, 118) of the first plurality of elevations (18, 118) on the first main surface (14, 114), and / or that at least one elevation (22) of the second plurality of elevations (22) on the second main surface (16) has a height (H) which differs from a height (H) of at least one other elevation - 39 - (22) the second plurality of elevations (22) on the second main area (16) is different.

10. Bipolar plate (10, 110, 210) according to one of the preceding claims, characterized in that at least one projection (18, 118) of the first plurality of projections (18, 118) on the first main surface (14, 114) has a height (H) which differs from the height (H) of at least one projection (22) of the second plurality of projections (22) on the second main surface (16), wherein, in particular, the height (H) of the at least one projection (18, 118) of the first plurality of projections (18, 118) on the first main surface (14, 114) differs by a factor of 0.5 to 2.0, advantageously by 1.1 to 1.5, and is in particular higher, than the height (H) of the at least one projection (22) of the second plurality of projections (22) on the second main surface (16), and / or that the bipolar plate (10, 110, 210) welding surfaces (66) which are designed to be connected to a respective section of a bipolar plate (10, 110,210) arranged electrode (52) to come into contact with each other in order to be connectable.

11. Stack (38, 338) for the construction of an electrochemical reactor, comprising at least one first (10a) and at least one second (10b) bipolar plate according to one of the preceding claims.

12. Stack (38, 338) according to the preceding stack claim, characterized in that the stack (38, 338) comprises at least one electrode (52, 352), wherein the electrode (352) has at least one projection (390) which is connected to the first (10a, 310a) or second (10b) bipolar plate, in particular welded to at least one welding surface (394).

13. Stack (38, 338) after the previous stack claim, - 40 - characterized in that the at least one projection (390) of the at least one electrode (352) comprises a formed section (392b) which is formed by a forming process downstream of the primary forming process, wherein the at least one electrode (352) is connected to the first (10a, 310a) or second (10b) bipolar plate in the region of the formed section (392b) of the at least one projection (390), wherein in particular a welding surface (394) is arranged on the formed section (392b) of the at least one projection (390) of the electrode (352), which is configured to be metallurgically joined to the first (10a, 310a) or second (10b) bipolar plate using a welding process.

14. Stack (38, 338) according to the preceding stack claim, characterized in that the at least one projection (390) of the at least one electrode (352) comprises a recess (396), wherein the recess (396) is arranged such that the welding surface (394) of the formed section (392b) of the at least one projection (390) is accessible for a welding process of the electrode (352) with the first (10a, 310a) or second (10b) bipolar plate, wherein in particular the recess (396) is arranged to at least partially cover the associated welding surface (394) when viewed along a Z-direction which is orthogonal to a main surface of the first (10a, 310a) or second (10b) bipolar plate.

15. Stack (38, 338) according to one of the preceding stack claims, characterized in that the stack (38) comprises at least one electrode (52, 352) which is connected, in particular welded, to the bipolar plate (10, 110, 210, 310) at at least one tolerance compensation device, in particular at at least one plateau (66). - 41 - 16. Stack (38, 338) according to one of the preceding stack claims, characterized in that the at least one electrode (52, 352) is an anode, wherein the anode comprises a plate-like base body having a first main surface and a second main surface which extend substantially parallel to each other, wherein in particular the first main surface has a surface which is electrically insulating, preferably by means of a catalytic coating, and the second main surface has a surface which is electrically insulating, preferably by means of a thermal coating.

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