ELECTROCHEMICAL REACTOR WITH CIRCULAR SEAL

Abstract

Described and illustrated is an electrochemical reactor (1), in particular a redox flow battery, fuel cell, electrolyzer or electrosynthesis cell, with a cell stack (Z) comprising a plurality of cells (2) stacked in a stacking direction (R), each cell (2) having at least one cell frame (12), a seal (13) being provided circumferentially around a cell interior (14) between at least two adjacent cell frames (12), and the seal (13) being provided at least partially in adjacent grooves (20, 21) of the adjacent cell frames (12).In order to achieve an improved seal, it is provided that the cross section of at least one groove (21) has an inner region (24) with a lower region of the groove base (27) and an outer region (25) with a higher region of the groove base (27), that the inner region (24) of the groove (21) and the outer region (25) of the groove (21) are connected to one another, in particular directly, via a step (26) of the groove base (27), and that the seal (13) bears against the at least one step (26).

Description

The invention relates to an electrochemical reactor, in particular a redox flow battery, fuel cell, electrolyser or electrochemical cell, having a cell stack comprising a plurality of cells stacked in a stacking direction, wherein each cell has at least one cell frame, wherein a seal is provided between at least two adjacent cell frames circumferentially around a cell interior and wherein the seal is provided in each case at least partially in adjacent grooves of the adjacent cell frames.Electrochemical reactors are known in various configurations. Redox reactions take place in the electrochemical reactors, it being possible for these reactions to be driven by a voltage difference applied from the outside, as is the case, for example, when charging a redox flow battery and when operating an electrolyser or an electrosynthesizing cell. In an electrolyser, a chemical reaction is carried out with the aid of an electric current in the form of an electrolysis to produce a product, for example in the form of hydrogen. Electrochemical synthesis processes take place in an electrosynthesizing cell with a voltage applied to the cell. Thus, for example, hydrogen peroxide can be synthesized from oxygen and water and organic basic chemicals from carbon dioxide and water in electrosynthesizing cells. Alternatively, the redox reactions taking place in the electrochemical reactor can, however, also be used to generate an electrical voltage. This is the case, for example, when discharging a redox flow battery or when operating a fuel cell.The electrochemical reactors of the type mentioned are generally constructed from a plurality of electrochemical cells in each of which the corresponding redox reaction takes place. The individual cells of an electrochemical reactor, such as an accumulator, are often arranged in a row or stacked one on top of the other. In this context, one therefore also speaks of a cell stack. Depending on the application, cell stacks allow in a simple manner the provision of a greater voltage or a greater product stream of the product to be produced. Corresponding cell stacks and their uses have been known for a long time and from a wide variety of applications, which is why they will not be discussed in detail here.The individual electrochemical cells are composed of half cells which comprise electrodes which are separated from one another by a separator. The electrodes and the separator of a cell are integrated in an interior space which can be provided by at least one cell frame. If necessary, a cell can also have a plurality of cell frames, for example one cell frame per half cell of the electrochemical cell. The electrodes, the at least one cell frame and the separator are provided at least substantially parallel to each other. This results in a lamination which extends in a so-called stacking direction. The individual cells of a cell stack can be separated from one another by so-called bipolar plates. In this case, an anode and a cathode of adjacent cells are regularly located on the opposite sides of the bipolar plates. In addition, the anode and the cathode are typically each in direct, electrically conductive contact with the at least one bipolar plate arranged therebetween.The cell frames and bipolar plates are typically formed from different materials, although for cost and manufacturing reasons cell frames and bipolar plates comprising at least one thermoplastic may be considered in some cases. In order to be able to provide sufficient electrical conductivity of the bipolar plates, the bipolar plates often also have an electrically conductive filler, for example in the form of fine particles, such as graphite or carbon black, in addition to the thermoplastic material.The separator may comprise an electrolyte required for the operation of the electrochemical reactor, wherein the separator may comprise an open-pore porous structure in which a liquid electrolyte may be accommodated. However, it can also be provided that the electrodes are in contact with the electrolytes, wherein the electrolytes and the electrodes of a cell are separated by the separator, for example in the form of a membrane. Separators that hold an electrolyte can be used in fuel cells, such as polymer electrolyte fuel cells (PEM) or solid oxide fuel cells (SOFC), while electrolytes separated by the separator, for example in the form of a membrane, can be used in redox flow batteries through which flow takes place. In the case of redox flow batteries, the electrolytes can flow through the electrodes at least partially.In some cases, the separator itself may provide the electrolyte, such as in the case of a polymer electrolyte fuel cell or a solid oxide fuel cell. In such fuel cells, the separator is divided into two, one part of the separator being flowed through by a hydrogen-containing gas and the other part of the separator being flowed through by an oxygen-containing gas. The transition of the gases from one part of the separator into the other part of the separator is prevented by a membrane which, however, allows the transition of charge carriers. Here too, the entirety of the two parts of the separator and of the membrane can be understood as the separator between the electrodes. The exact construction of the separator is of any consequence in connection with the invention. In the case of a polymer electrolyte fuel cell, the membrane is made of a solid polymer, while in a solid oxide fuel cell, an oxide ceramic electrolyte is used. However, other membranes can also be provided in other fuel cells or membranes can be completely dispensed with.However, electrochemical reactors in the form of fuel cells do not even manage without a fluid. These are working fluids in the form of hydrogen or oxygen-containing gases flowing through the separator in the anode space and the separator in the cathode space. Consequently, in the case of the electrochemical reactors, it is to be ensured that no undesired escape of fluid, i.e. for example a leakage, occurs during operation. In this case, it is initially immaterial whether the fluid is an electrolyte or a working fluid.Against this background, during the production of a corresponding electrochemical reactor, it is necessary to take care of the tightness thereof. This can be achieved by bracing the cell stack between two end plates. In this case, the cells and / or the individual parts of the cells, in particular their cell frames, are pressed against one another, wherein seals can be provided between the cells and / or the individual parts of the cells, in particular the cell frames. In order to provide adequate tightness, an adequate surface pressure must be applied to the seals when the cell stack is braced.The purpose of the seals is to prevent the exchange of solid, liquid and / or gaseous media between two adjacent spaces. The additional seals disposed between the primary sealing surfaces to be sealed are referred to as secondary sealing members that provide secondary sealing surfaces. Absolute tightness cannot be achieved independently of the seals and the contact pressures, since diffusion processes cannot be ruled out at any rate.Typically, detachable seals in the form of flat seals, shaped seals such as O-rings, FIP (shaped-in-place) seals or CIP (cut-in-place) seals are possible, which allow significantly lower contact pressures than if the secondary seals were dispensed with. At the same time, the secondary seals take up installation space, so that the cell stacks have larger dimensions in the stacking direction through the seals. In addition, the prestressing forces for providing the required contact pressures can be reduced if smaller sealing surfaces are required.Round ring seals are frequently used, which are also referred to as O-ring seals and are accommodated in grooves, in particular rectangular grooves. In the case of FIP and CIP (Cut-In-Place) seals, a sealing compound is applied between the two primary sealing surfaces and cured under UV light or heat input after the joining. Therefore, these seals are also referred to as integrated elastomeric seals.Round ring seals offer the advantage, for example, compared to flat seals for use in electrochemical reactors, that they are accommodated at least partially in at least one groove, which reduces the dimensions in the stacking direction of the stack. In addition, the forces required for sealing are lower. Round ring seals are usually accommodated in grooves with a rectangular cross section, wherein the groove depth of the at least one groove is smaller than the diameter of the round ring seal, at least insofar as it has a round cross section. The compression can typically be 15% to 30% of the diameter.Electrochemical reactors comprising a seal are known, for example, from DE 10 2019 213 786 A1, CN 103 840 180 A and DE 696 20 452 T2.The sealing of electrochemical reactors is not yet completely satisfactory despite the known sealing technologies.It is therefore an object of the present invention to design and further develop electrochemical reactors of the type mentioned at the beginning and described in more detail above in such a way that an improved seal can be obtained.This object is achieved in an electrochemical reactor according to the preamble of claim 1 in that the cross section of at least one groove has an inner region with a lower lying region of the groove base and an outer region with a higher lying region of the groove base, in that the inner region of the groove and the outer region of the groove are connected to one another, in particular directly, via a step of the groove base, and in that the seal bears against the at least one step.According to the invention, the seal is not accommodated in two grooves with a purely rectangular, square, round or oval cross section. The cross section of at least one groove of a cell frame, in which the seal is at least partially accommodated, rather has at least two regions of different depth, which are separated from one another by a step. In an inner region, the groove base of the corresponding groove is arranged lower than in an adjacent outer region. The outer region is provided closer to an edge of the corresponding groove than the inner region of the corresponding groove. The inner here therefore does not necessarily mean the inner in the direction of the cell interior. The inner region can also be arranged on the side of the groove facing away from the cell interior and vice versa.The inner region and the outer region are separated from one another by at least one step in the groove base, against which the seal bears. The seal is preferably deformed by the step, namely in particular deformed straight at the step, in order to provide an increased tightness. A special tightness can be achieved in principle if the seal rests against the groove base on both sides of the step, thus against the inner region and the outer region of the corresponding groove. For reasons of tightness, it is further preferred if the step has an at least substantially rectangular shape. Then, the seal is locally deformed particularly strongly by the step in order to provide a high tightness.If the at least one step has sufficient shape, position in the groove and size, a single step may be sufficient to provide very good sealing. Then, virtually no liquid and / or gas can pass the seal via the step. It is likewise desirable here if the seal also sealingly abuts the opposite cell frame in its opposite groove. Then, the region between the two cell frames is protected against excessive transfer of liquid and / or gas across the seal and the corresponding region is thus well sealed.In a first particularly preferred embodiment of the electrochemical reactor, it is provided for increasing the tightness that the cross section of the at least one groove has an inner region with a deep lying region of the groove base and two outer regions each with a higher lying region of the groove base. Then, an outer region can be arranged on one of the two sides of the inner region. The outer regions are then assigned in particular to the two edges of the groove, while the inner region is assigned to a central region of the groove. In addition, for space reasons, it is preferred if the inner region of the groove and the outer regions of the groove are each connected to one another, in particular directly, via a step of the groove base. The seal can then lie very tightly against the steps and thus ensure a high degree of tightness.For a high tightness of the connection between the two adjacent cell frames, the seal should also lie tightly against the other, opposite groove. This can be achieved by arranging the edges of the opening of the groove having the at least one step further outwards relative to the inner region than the edges of the opening of the adjacent groove. In this case, the seal may be clamped between at least an outer portion of the one groove and a portion outside the opposing groove. The region of the clamping thereby forms a high tightness. This applies to a particular extent if the step is arranged further inward relative to the inner region than the associated edge of the opening of the adjacent groove. From a central point of the at least one groove, the at least one step is thus arranged further inward than the outer edge of the opposite groove. When two steps are disposed on opposite sides of the inner portion of one groove, both outer edges of the other groove may be disposed more outward than the steps, respectively.Alternatively or additionally, the groove having at least one step can form sections of a sealing channel on the one hand with respect to the inner region further outward and the adjacent cell frame can form sections of a sealing channel on the other hand with respect to the opening of the groove of this cell frame further outward. The sealing channel is formed between the adjacent cell frame on the one hand and the groove having the at least one step, so that the seal can abut the two adjacent cell frames in the sealing channel. The contact of the seal on the opposite sealing surfaces of the sealing channel can lead to increased tightness.The seal can be used particularly expediently if it has a round, oval or rectangular cross section. Then, the gasket fits well into the grooves of the opposite cell frames. Alternatively, the electrochemical reactor may be a redox flow battery, a fuel cell, an electrolyser or an electrosynthesizer having a plurality of stacked electrochemical cells. Independently thereof, the cell frames can each be the only cell frame of two adjacent half cells forming an electrochemical cell. However, it is also conceivable for the electrochemical cell to comprise more than two stacked cell frames and / or for a half cell to have more than one cell frame.In a particularly preferred electrochemical reactor, in which the invention is used to a particular extent, a separator in the form of an, in particular semipermeable, membrane for separating two cell interiors and / or a bipolar plate is provided between the adjacent grooves. Thus, not only the cell frames can be sealed, but also the separator and / or the bipolar plate at the same time. It is understood that the separator and / or the bipolar plate is preferably provided only in sections between the adjacent grooves and otherwise delimit two adjacent cell interiors from one another.For reasons of tightness, it may be expedient here if the separator or the bipolar plate bears against the at least one step. In addition, this can be done in such a way that the separator or the bipolar plate both abuts the step on one side and at least partially abuts the inner region of the associated groove. Thus, the effective sealing surface can be increased. In addition, it can be favorable for the tightness if the other side in the region of the at least one step and / or in the inner region of the groove abuts the seal instead of the cell frame. The separator or the bipolar plate is thus clamped between the one cell frame and the adjacent seal.For the tightness and the space requirement, it can be expedient if a groove, in particular one opposite the at least one step, has a ratio of groove width to groove depth of between 0.5 and 5, preferably between 1 and 3, in particular between 1.5 and 2.5. Alternatively or additionally, the groove having the at least one step can have a ratio of groove width to groove depth of between 12 and 2, preferably between 9 and 4, in particular between 8 and 5, for the same reasons.For the tightness and the space requirement, it can be appropriate independently of this that the width of the inner region to the width of the groove having the at least one step has a ratio between 0.1 and 1.2, preferably between 0.3 and 1, in particular between 0.5 and 0.7. However, it is also possible in a suitable manner for the height of the at least one step to the depth of the groove having the at least one step to have a ratio of between 0.2 and 0.8, preferably between 0.3 and 0.7, in particular between 0.4 and 0.6.For the tightness and the space requirement, it can also be expedient if the height of the at least one step relative to the height of the sealing channel has a ratio between 0.3 and 2, preferably between 0.6 and 1.5, in particular between 0.8 and 1.2. However, the width of the one groove, in particular the groove opposite the at least one step, can also expediently have a ratio of 0.6 to 1 to the width of the groove having the at least one step, preferably between 0.7 and 0.95, in particular between 0.8 and 0.9.For the tightness and the space requirement, it can be appropriate independently of this that the width of the one groove, in particular the groove opposite the at least one step, has a ratio of between 1 and 2, preferably between 1.05 and 1.6, in particular between 1.1 and 1.3, to the width of the inner region of the groove having at least one step. However, it is also possible in a suitable manner for the groove depth of the one groove, in particular the groove opposite the at least one step, to have a ratio of between 1 and 5, preferably between 1.5 and 4, in particular between 2 and 3, to the groove depth of the groove having the at least one step.The invention is explained in more detail below with reference to a drawing which merely represents an exemplary embodiment. The drawing shows FIG. 1 shows an electrochemical reactor according to the invention in a schematic sectional view transversely to the stacking direction of the cells of the one cell stack, FIG. 2 shows a cell frame of the electrochemical reactor from FIG. 1 in a plan view, FIG. 3 shows a detail of the electrochemical reactor from FIG. 1 in the region of the sealing of two cell frames with respect to one another in a sectional view, and FIG. 4 shows a further detail of the electrochemical reactor from FIG. 1 in the region of two cell frames with respect to one another in a sectional view.FIG. 1 shows an electrochemical reactor 1 in the form of a redox flow battery with a bipolar structure in a sectional view from the side. The electrochemical reactor 1 comprises a stack (cell stack Z) of individual cells 2 which are arranged next to one another in a stacking direction R. Bipolar plates 3 are provided between the individual cells 2, each of which is adjacent to half cells 4 and which abut on one side against a negative electrode 5 of a cell 2 and abut on the opposite side against a positive electrode 6 of an adjacent cell 2. At each of the two opposite ends of the electrochemical reactor 1, an end plate 7 with internal, electrically conductive printed circuit boards 8 is provided, via which voltage can be tapped off at the electrochemical reactor 1 and via which voltage can be applied to the electrochemical reactor 1. This is not shown in detail.Each cell 2 comprises two electrodes 5, 6 which are separated from one another by a separator 9 which is arranged between the electrodes 5, 6 and which can be designed as a preferably semipermeable membrane. In the electrochemical reactor 1 shown, the two electrodes 5, 6 are in contact with an electrolyte 10, 11 in each case. the electrodes 5, 6 are accommodated in a cell frame 12 in each case and are in direct contact with the adjacent bipolar plates 3 in each case. The cell frames 12 are clamped to one another by an external clamping device and are sealed with respect to one another by a seal 13. In this case, a separator 9, in particular in the form of a semipermeable membrane, or a bipolar plate 3 is provided in each case between the cell frames 12 adjoining one another.FIG. 2 shows an exemplary cell frame 12 of the electrochemical reactor 1 of FIG. 1. The cell frame 12 encloses a cell interior 14, in which an electrode 5, 6 around which an electrolyte 10, 11 flows is located. The electrolyte 10, 11 is supplied via an inlet opening 15 in the cell frame 12 and supplied via inlet channels 16 to the cell interior 14. After flowing through the cell interior 14, the electrolyte 10, 11 is collected via outlet channels 17 and an outlet opening 18 is discharged. The further openings 19 serve for the transport of another electrolyte 11, 10 to the cell channel spaces 14 of other cell frames 12, and a circumferential groove 20 is provided in the edge region in the cell frame 12 for receiving the seal 13 in the form of a round ring seal.FIG. 3 shows a detail of two adjacent cell frames 12 which are sealed with respect to one another by means of the seal 13 in the form of a circumferential round ring seal. The two adjacent cell frames 12 have grooves 20, 21 with openings 22, 23, which each point in the direction of the respective other groove 20, 21 and overlap one another. The grooves 20, 21 of the cell frames 12 shown and thus preferred are of different widths and different depths. While the groove 20 shown above has a rectangular or square cross section, the shape of the groove 21 of the cell frame 12 shown below is of somewhat more complex construction. This groove 21 has an inner, deeper region 24 and two regions 25 which are outer and shallower than the latter. The groove depth in the inner region 24 is therefore greater than the groove depth in the outer regions 25, and the outer regions 25 adjoin the inner region 24 directly in the groove 21 shown and preferred in this respect, wherein the inner region 24 is separated from the outer regions 25 in each case by a step 26 in the groove base 27. Steps 26 in the groove 21 shown and preferred in this respect are at least substantially rectangular, one leg being oriented parallel to the depth of groove 21 and one leg being oriented parallel to the width of groove 21.In the groove 21 shown and preferred in this respect, the inner region 24 is more than twice as wide as the two outer regions 25 together. In addition, the groove 21 having the steps 26 is less than half as deep as the adjacent groove 20, and the groove 21 having the steps 26 is further wider than the adjacent groove 20, and the groove 21 having the steps 26 is protruded outward on both sides opposite to the adjacent groove 20. A sealing channel 28 is thus formed between the groove 21 having the steps 26 in the region of the outer regions 25 and the adjacent cell frame 12 in the region adjacent to its groove 20, in which the seal 13 is partially accommodated and squeezed by both cell frames 12 with high forces. In addition, the seal 13 is squeezed at the steps 26 with high forces, the seal 13 resting against the steps 26 as well as against the inner region 24 and the outer regions 25 of the corresponding groove 21. The seal 13 is large enough in cross section that the seal 13 rests firmly against the groove base 29 of the groove 20 opposite the steps 26. For the sake of better illustration, the regions 30 of increased deformation of the seal 13 and / or increased compression of the seal 13 are schematically indicated by hatching. In the case of the grooves 20, 21 which are illustrated and to this extent preferred, the inner region 24 is narrower than the width of the opposite groove 20. The groove base 27 of the inner region 24 is also approximately twice as deep as the groove 21 in the outer regions 25, and the outer regions 25 are configured approximately equally deep in the groove 21 shown and preferred in this respect. Moreover, the groove 20 which is illustrated and is preferred to this extent and has no step 26 is at least one and a half times as wide as deep, while the groove 21 which has the steps 26 is at least three times as wide as deep.FIG. 4 shows a detail of two adjacent cell frames 12 analogous to FIG. 3. In contrast to this, however, a separator 9 in the form of a membrane is provided between the seal 13 and the groove base 27 of the groove 21 having the steps 26. The separator 9 extends from the cell interior 14 into the inner region 24 of the groove 21 having the steps 26, in particular at least substantially up to the step 26 facing away from the cell interior 14, and is in contact there with the groove base 27 and the seal 13 accommodated in the associated groove 21. The seal 13 does not bear directly against the step 26 assigned to the cell interior 14, but rather against the separator 9, and therefore indirectly. However, the seal 13 bears directly against the opposite step 26 of the groove 21 having the steps 26.Reference numerals denote reference numerals1 Electrochemical reactor 2 Cell 3 Bipolar plate 4 Half cell 5 Electrode 6 Electrode 7 End plate 8 Printed circuit board 9 Separator 10 Electrolyte 11 Electrolyte 12 Cell frame 13 Seal 14 Cell interior 15 Inlet opening 16 Inlet channel 17 Outlet channel 18 Outlet opening 19 Opening Cell frame 20 Groove 21 Groove 22 Opening Groove 23 Opening Groove 24 Inner region 25 Outer region 26 Step 27 Groove base 28 Seal channel 29 Groove base 30 Region of increased deformation R Stacking direction Z Cell stack / cell stack

Claims

Electrochemical reactor (1), in particular redox flow battery, fuel cell, electrolyser or electrosynthesizing cell, having a cell stack (Z) composed of a plurality of cells (2) stacked in a stacking direction (R), wherein each cell (2) has at least one cell frame (12), wherein a seal (13) is present between at least two adjacent cell frames (12) circumferentially around a cell interior (14), and wherein the seal (13) is present in each case at least partially in adjacent grooves (20, 21) of the adjacent cell frames (12), characterized in that the cross section of at least one groove (21) has an inner region (24) with a lower-lying region of the groove base (27) and an outer region (25) with a higher-lying region of the groove base (27), the inner region (24) of the groove (21) and the outer region (25) of the groove (21) are connected to one another, in particular directly, via a step (26) of the groove base (27), and the seal (13) bears against the at least one step (26).Electrochemical reactor according to Claim 1, characterized in that the cross section of at least one groove (21) has an inner region (24) with a lower-lying region of the groove base (27) and two outer regions (25) arranged on both sides of the inner region (24), each having a higher-lying region of the groove base (27), in that the inner region (24) of the groove (21) and the outer regions (25) of the groove (21) are each connected to one another, in particular directly, via a step (26) of the groove base (27), and in that the seal (13) bears against the two steps (26).Electrochemical reactor according to Claim 1 or 2, characterized in that the edges of the opening (23) of the groove (21) having the at least one step (26) are arranged further outwards relative to the inner region (24) than the edges of the opening (22) of the adjacent groove (20), and in that, preferably, the step (26) is arranged further inwards relative to the inner region (24) than the associated edge of the opening (22) of the adjacent groove (20).Electrochemical reactor according to one of Claims 1 to 3, characterized in that the groove (21) having at least one step (26) is further outwards with respect to the inner region (24), and the adjacent cell frame (12) is further outwards at least in sections with respect to the opening of the groove (20) of the adjacent cell frame (12), forming a sealing channel (28) between the adjacent cell frame (12) and the groove (21) having the at least one step (26), and in that the seal (13) bears against the two adjacent cell frames (12) in the sealing channel (28).Electrochemical reactor according to one of Claims 1 to 4, characterized in that the seal (13) has a round, oval or rectangular cross section and / or in that the electrochemical reactor (1) is a redox flow battery and / or in that the cell frame (12) is the only cell frame (12) of a half cell (4).Electrochemical reactor according to one of Claims 1 to 5, characterized in that a separator (9) is present in the form of an, in particular semipermeable, membrane for separating two cell interiors (14) and / or a bipolar plate (3), in particular in sections, between the adjacent grooves (20, 21).Electrochemical reactor according to Claim 6, characterized in that the separator (9) or the bipolar plate (3) bears against the at least one step (26), and in that, preferably, the separator (9) or the bipolar plate (3) bears against the step (26) on one side and at least in sections against the inner region (24) of the associated groove (21), and in that, further preferably, the other side bears against the seal (13) in the region of the at least one step (26) and / or in the inner region (24) of the groove (21).Electrochemical reactor according to one of Claims 1 to 7, characterized in that the one groove (20), in particular one which lies opposite the at least one step (26), has a ratio of groove width to groove depth of between 0.5 and 5, preferably between 1 and 3, in particular between 1.5 and 2.5, and / or in that the groove having the at least one step (26) has a ratio of groove width to groove depth of between 12 and 2, preferably between 9 and 4, in particular between 8 and 5.Electrochemical reactor according to one of Claims 1 to 8, characterized in that the width of the inner region (24) to the width of the groove (21) having the at least one step (26) has a ratio of between 0.1 and 1.2, preferably between 0.3 and 1, in particular between 0.5 and 0.7.Electrochemical reactor according to one of Claims 1 to 9, characterized in that the height of the at least one step (26) relative to the depth of the groove (21) having the at least one step (26) has a ratio of between 0.2 and 0.8, preferably between 0.3 and 0.7, in particular between 0.4 and 0.6.Electrochemical reactor according to one of Claims 1 to 10, characterized in that the height of the at least one step (26) relative to the height of the sealing channel (28) has a ratio of between 0.3 and 2, preferably between 0.6 and 1.5, in particular between 0.8 and 1.2.Electrochemical reactor according to one of Claims 1 to 11, characterized in that the width of the one groove (20), in particular one which lies opposite the at least one step (26), has a ratio of between 0.6 and 1, preferably between 0.7 and 0.95, in particular between 0.8 and 0.9, to the width of the groove (21) which has the at least one step (26).Electrochemical reactor according to one of Claims 1 to 12, characterized in that the width of the one groove (20), in particular one which lies opposite the at least one step (26), has a ratio of between 1 and 2, preferably between 1.05 and 1.6, in particular between 1.1 and 1.3, to the width of the inner region (24) of the groove (21) which has at least one step (26).Electrochemical reactor according to one of Claims 1 to 13, characterized in that the groove depth of the one groove (20), in particular one which lies opposite the at least one step (16), has a ratio of between 1 and 5, preferably between 1.5 and 4, in particular between 2 and 3, to the groove depth of the groove (21) which has the at least one step (26).

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