Electrochemical reactor and method for operating an electrochemical reactor

Abstract

The invention relates to an electrochemical reactor (1), in particular a redox flow battery, fuel cell, electrolyser or electrosynthesis cell, comprising a cell stack (Z) formed by a plurality of cells (2) that are stacked in a stacking direction (R) and separated from one another by at least one bipolar plate (3), wherein the cells (2) each have two electrodes (5, 6) and a separator (10) arranged between the two electrodes (5, 6), and wherein the at least one bipolar plate (3) is flexible. So that bulk transport and material distribution can be increased with low constructional and equipment requirements, and with low material stress, according to the invention, an oscillator (13) causing the at least one bipolar plate (3) to vibrate is integrated into the bipolar plate (3).

Description

[0001] Electrochemical reactor and method for operating an electrochemical reactor

[0002] The invention relates to an electrochemical reactor, in particular a redox flow battery, fuel cell, electrolyzer, or electrosynthesis cell, comprising a cell stack consisting of a plurality of cells, each separated from one another by at least one bipolar plate and stacked in a stacking direction. The cells each have two electrodes and a separator arranged between the two electrodes, and the at least one bipolar plate is flexible. Furthermore, the invention relates to a method for operating an electrochemical reactor.

[0003] Electrochemical reactors are known in various designs. Redox reactions take place in electrochemical reactors, whereby these reactions can be driven by an externally applied voltage difference, as is the case, for example, when charging a redox flow battery or when operating an electrolyzer or an electrosynthesis cell. In an electrolyzer, a chemical reaction in the form of electrolysis is carried out with the help of an electric current to produce a product, such as hydrogen. In an electrosynthesis cell, electrochemical synthesis processes take place when the cell is subjected to a voltage. For example, hydrogen peroxide can be synthesized from oxygen and water, and basic organic chemicals from carbon dioxide and water.Alternatively, the redox reactions taking place in the electrochemical reactor can also be used to generate an electrical voltage. This is the case, for example, when discharging a redox flow battery or operating a fuel cell.

[0004] Electrochemical reactors of this type are typically constructed from a plurality of electrochemical cells, each of which carries out a corresponding redox reaction. The individual cells of a battery are often arranged in a row or stacked on top of each other. In this context, they are therefore also referred to as a cell stack. Depending on the application, cell stacks allow for the simple provision of a higher voltage or a larger product flow of the product being manufactured. Such cell stacks and their uses have been known for a long time and in a wide variety of applications, so they need not be discussed in detail here.

[0005] The individual electrochemical cells are composed of half-cells comprising electrodes 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 required, a cell can also have multiple 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 arranged at least substantially parallel to one another. This results in a layering that 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 usually located on 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.

[0006] The cell frames and bipolar plates are typically made of different materials, although for cost and manufacturing reasons, cell frames and bipolar plates comprising at least one thermoplastic material are sometimes considered. To ensure sufficient electrical conductivity of the bipolar plates, the bipolar plates often contain an electrically conductive filler in addition to the thermoplastic material, for example, in the form of fine particles such as graphite or carbon black.

[0007] The separator can contain an electrolyte required for the operation of the electrochemical reactor. The separator can have an open-pore, porous structure in which a liquid electrolyte can be accommodated. However, it can also be provided that the electrodes are in contact with the electrolyte, with the electrolytes and the electrodes of a cell being separated by the separator, for example in the form of a membrane. Separators that contain 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. In the case of redox flow batteries, the electrolytes can flow at least partially through the electrodes.

[0008] In some cases, the separator itself can provide the electrolyte, as is the case with a polymer electrolyte fuel cell or a solid oxide fuel cell. In such fuel cells, the separator is divided into two parts, with a hydrogen-containing gas flowing through one part of the separator and an oxygen-containing gas flowing through the other part. The transfer of gases from one part of the separator to the other is prevented by a membrane, which, however, allows the transfer of charge carriers. Here, too, the entirety of the two parts of the separator and the membrane can be understood as the separator between the electrodes. The exact structure of the separator is of only limited importance in the context of the invention.In the case of a polymer electrolyte fuel cell, the membrane consists of a solid polymer, whereas a solid oxide fuel cell uses an oxide-ceramic electrolyte. Other fuel cells, however, may also utilize other membranes or even dispense with membranes altogether. However, electrochemical reactors in the form of fuel cells also require a fluid. This fluid is a working fluid in the form of gases containing hydrogen or oxygen flowing through the separator in the anode chamber and the separator in the cathode chamber. Consequently, care must be taken with electrochemical reactors to ensure that no undesired escape of fluid, such as a leak, occurs during operation. It is initially irrelevant whether the fluid is an electrolyte or a working fluid.

[0009] Against this background, the manufacture of a corresponding electrochemical reactor must ensure its tightness. This can be achieved by clamping the cell stack between two end plates. The cells and / or individual cell components are pressed against one another, with seals optionally provided between the cells and / or individual cell components. This is complex, and the cells and / or individual cell components must withstand high mechanical forces. To avoid this, it has already been proposed to weld the cells and / or individual cell components together in order to create smaller and more efficient cell stacks.

[0010] Mass transport and a homogeneous material distribution within the cells are also crucial for the efficiency of electrochemical reactors. For example, deposits of solids or fluids, as well as air pockets, can occur within the cells, hindering mass transport processes and thus leading to electrochemical dead zones. These dead zones contribute little or nothing to the electrochemical reactions within the cell. Furthermore, these deposits can adversely affect the lifespan of the cells.

[0011] To prevent or dissolve such deposits, it has been proposed to vibrate the entire cell stack. However, this approach can loosen screw connections and connectors, subjecting the cell stack materials to significant stress. It has also been suggested to couple external vibrations into cell stacks via specific components, but this is complex in terms of design and equipment. Alternatively, vibration-generating actuators can be integrated into the cell stack. However, these actuators would then come into contact with usually corrosive reaction fluids or could lead to significant stress on the components caused to vibrate.

[0012] Therefore, the object of the present invention is to design and further develop the electrochemical reactor and the method of the type mentioned at the outset and explained in more detail above in such a way that the mass transport and the material distribution can be increased with little constructional and equipment expenditure and low material stress.

[0013] This object is achieved in an electrochemical reactor according to the preamble of claim 1 in that an oscillator which excites the at least one bipolar plate to oscillate is integrated into the bipolar plate.

[0014] The above object is further achieved according to claim 10 by a method for operating an electrochemical reactor according to one of claims 1 to 9,

[0015] - in which the at least one oscillator is excited to oscillate at least in phases and

[0016] - in which the oscillator causes at least one bipolar plate to oscillate.

[0017] According to the invention, a cell stack with at least one flexible bipolar plate is used, which can be set into vibration without great effort and without excessive loads on the bipolar plate. Due to the flexibility of the bipolar plate, it cannot break despite the vibrations, even if vibrations with high amplitudes are generated. Furthermore, the bipolar plate can also be set into vibration easily, which requires only small forces. In addition, due to the flexibility, the vibrations are only partially transmitted to adjacent components, which can thus be protected from excessive mechanical stress. Last but not least, targeted deformation of the bipolar plates is also possible due to the flexibility provided, whereby deposits and air inclusions can be specifically counteracted.

[0018] It is understood that the corresponding bipolar plate does not have to be continuously vibrated, although this may be possible and even preferred. However, the method provides for the at least one bipolar plate to be vibrated at least in phases. For example, vibration of the at least one bipolar plate can be stimulated occasionally or at regular intervals in order to dissolve deposits or air pockets that have built up and to flush them out of the affected half-cell. If the vibrations are generated at least substantially continuously, it may be possible to prevent the deposits or air pockets from forming at all.

[0019] It is also understood that a cell stack can typically comprise a whole series of bipolar plates and that an oscillator does not have to be integrated into each of these bipolar plates. If necessary, the equipment and construction expenditure can be kept to a minimum by integrating an oscillator into no more bipolar plates than necessary or by exciting no more bipolar plates than necessary to oscillate. In this context, it can also be provided that different bipolar plates are set into oscillation at different times, for example one after the other. If individual bipolar plates cannot be excited to oscillate themselves, then it is advisable to make neighboring or nearby bipolar plates oscillate so that the oscillation of at least one bipolar plate can be transmitted to at least one other bipolar plate or at least one other cell.The oscillator is preferably the component that can generate the oscillations of the bipolar plate. However, the oscillations of the bipolar plate can still be induced, i.e., excited, from outside. Therefore, an actuator is preferably provided outside the actual cell stack, which excites the oscillator in the at least one bipolar plate to oscillate. Since the oscillator is integrated into the bipolar plate, oscillation of the oscillator directly leads to oscillation of the bipolar plate. Therefore, no actuator is required, which must be in external contact with the bipolar plate and would otherwise be unnecessary for the operation of the cell stack.

[0020] To minimize material stress and prevent deposits, it may be particularly advantageous if the vibrations generated by at least one oscillator are ultrasonic vibrations. Ultrasonic vibrations can have frequencies between 20 kHz and 20 GHz. However, other frequencies are also possible.

[0021] In a particularly preferred embodiment of the electrochemical reactor, the oscillator is formed by at least one flexoelectric plastic, at least one hydrogel, at least one shape memory polymer, at least one piezoelectric, and / or at least one magnetostrictive material. This allows for simple yet effective integration of the oscillator into the bipolar plate without significantly impairing its electrical function.

[0022] Flexoelectric plastics, such as PVDF, are dielectric plastics that develop polarization within the plastic when subjected to mechanical stress, and vice versa. This makes it possible to bend or deform components made at least partially of flexoelectric plastics, such as bipolar plates, at least slightly by applying an electrical voltage. The bipolar plate does not have to be made entirely of flexoelectric plastics. It may be sufficient for the flexoelectric plastics to constitute part of the bipolar plate. The bipolar plate can then additionally contain a thermoplastic and an electrically conductive filler, if required.

[0023] Hydrogels are water-binding and water-insoluble polymers that form a gel. Water absorption can occur physically or chemically. Hydrophilic polymer components such as sodium polyacrylate or polyaxamers incorporated into the bipolar plate allow the bipolar plates to swell, resulting in a considerable increase in volume, as is known, for example, from so-called superabsorbents. By adding and removing water to the hydrogel of a bipolar plate, its volume can be varied. If this is done in a sufficiently rapid cycle, the bipolar plate can be set into vibration. If required, the bipolar plate can contain, in addition to the at least one hydrogel, a thermoplastic and an electrically conductive filler.

[0024] Shape memory polymers are particularly suitable for polymers that exhibit a two-way memory effect, as is known from shape memory alloys. Such shape memory polymers can be, for example, polyurethanes or block copolymers. Once the shape memory polymers have been programmed to a specific shape, usually at elevated temperature, they can be switched from one shape to another by varying the temperature or a magnetic field. Here, too, the bipolar plate can be formed only partially from a shape memory polymer so as not to impair its electrical and mechanical properties. In this case, the bipolar plate can also contain, for example, a thermoplastic and an electrically conductive filler.

[0025] Piezoelectric materials, such as quartz, lithium niobate, gallium orthophosphate, or lead zirconate titanates, exhibit a change in electrical polarization and thus the occurrence of an electrical voltage when they are elastically deformed (direct piezoelectric effect). Conversely, materials deform when an electrical voltage is applied (inverse piezoelectric effect). If a voltage source is applied to a bipolar plate at least partially comprising a piezoelectric material, the bipolar plate can be deformed and thus caused to oscillate by varying the voltage. If a piezoelectric material is distributed throughout the bipolar plate, for example, the bipolar plate can also comprise a thermoplastic and an electrically conductive filler.

[0026] Magnetostrictive materials exhibit a property known as magnetostriction, which results in deformation of the magnetostrictive material as a result of an applied magnetic field. At constant volume, the corresponding body experiences an elastic change in length (Joule magnetostriction) due to the alignment of magnetically polar regions. A changing magnetic field can cause a bipolar plate comprising a magnetostrictive material to vibrate, even if the bipolar plate is only partially made of a magnetostrictive material. In this case, the bipolar plate can also contain, for example, a thermoplastic and an electrically conductive filler.

[0027] One of the aforementioned materials can be distributed throughout the bipolar plate, but it can also be provided that such a material is housed within an interior space of the bipolar plate. This makes it easy to excite the bipolar plate to oscillate without the oscillation-generating materials coming into contact with the electrodes. This can also facilitate the simpler and / or easier integration of the materials into the bipolar plate.

[0028] To easily and reliably oscillate the bipolar plate, it is advisable to couple the oscillator to an activation device. The oscillator itself can thus be passive, so to speak, and can be specifically activated via the activation device. Depending on the oscillator, this can be achieved simply by the activation device inducing periodic voltage changes, pressure changes, and / or temperature changes in the oscillator.

[0029] A simple yet effective bipolar plate can be provided as needed by forming the oscillator with at least one internal fluid volume filled with a fluid within the bipolar plate. The corresponding fluid volume is variable due to the elasticity of the bipolar plate itself. The fluid volume is also connected to a fluid supply via at least one supply line, through which fluid can be periodically added and removed. The addition and removal of fluid causes the fluid volume in the bipolar plate, and thus the bipolar plate itself, to expand before the fluid volume, and thus the bipolar plate, contracts again. In this way, an oscillation of the bipolar plate can be generated.

[0030] For simplicity and reliability, the oscillator can be provided between at least two electrically interconnected bipolar plate parts. The oscillator can thus be integrated into the bipolar plate as a separate component or part. It may be particularly preferred if the at least two bipolar plate parts form a bipolar cushion with the oscillator housed in the interior of the bipolar cushion. The oscillator is thus housed between the bipolar plate parts, which are conductively interconnected and each in electrical contact with one of the adjacent electrodes.

[0031] In principle, it is preferred if the at least one bipolar plate, the bipolar plate parts, and / or the bipolar cushion are formed at least predominantly from a thermoplastic and an electrically conductive filler. This allows for simple and cost-effective production and high elasticity of the bipolar plate. The high elasticity supports favorable vibration behavior of the bipolar plate. Production is particularly simple and cost-effective if the thermoplastic is formed at least predominantly from polyethylene and / or polypropylene. Alternatively or additionally, the filler can be formed at least predominantly from a carbon-containing material, such as graphite, carbon black, or carbon nanotubes, for the same reasons.

[0032] It can be particularly expedient and functional if the at least one oscillator is an integral component of the bipolar plate, the bipolar plate parts, and / or the bipolar cushion. The oscillator cannot therefore be omitted without impairing the function of the bipolar plate, the bipolar plate parts, and / or the bipolar cushion, even if no oscillations are to be generated. This is all the more true if the oscillator is incorporated as a disperse phase in a continuous phase comprising a thermoplastic. This allows for a fairly uniform and material-friendly deformation or oscillation of the bipolar plate. Furthermore, the electrically conductive filler can also be incorporated as a disperse phase in the continuous phase of the at least one thermoplastic.

[0033] To increase the longevity of the at least one bipolar plate, at least one bipolar plate with high elasticity can be used. Furthermore, to protect the at least one bipolar plate or the cell stack, it is expedient to subject the bipolar plate to low- or high-frequency oscillations. Furthermore, the amplitudes of the oscillations should not be too large to keep material stresses to a minimum. However, a certain amplitude may be necessary to prevent or reduce deposits and / or air inclusions.

[0034] To construct a long-lasting cell stack despite the at least periodically occurring vibrations, it may be advisable for the at least one separator and / or the two cell electrodes to be accommodated in a cavity of at least one cell frame. The cell stack can thus be easily stacked, which can make the cell stack more robust overall. In a first particularly preferred embodiment of the method, it is provided that the at least one bipolar plate is designed in the form of a volume-variable bipolar cushion. The volume of the bipolar plate can then be varied by supplying and removing fluid from the bipolar plate. This can generate vibration of the bipolar plate.Alternatively or additionally, electrolyte can be forced out of at least one half-cell by supplying fluid to the bipolar plate and / or electrolyte can be sucked into at least one half-cell by removing fluid from the bipolar plate. In other words, an electrolyte flow can be generated in the cell stack by varying the volume of the at least one bipolar plate. This flow can even convey electrolyte through the cell stack if required. If required, a pump and / or a pressure gradient can also be provided to assist the flow of electrolyte through the cell stack. However, such a pressure gradient and / or such a pump can also be dispensed with if required. In this case, the transport of the at least one electrolyte through the at least one half-cell can be effected, for example, exclusively by supplying and removing fluid to and from the at least one bipolar plate.

[0035] To reduce the electrical resistance in the cell stack, it may be appropriate to bring at least one electrode of the electrochemical reactor into contact exclusively with the at least one thermoplastic and / or with the filler of the bipolar plate. The oscillator can then be provided in a region of the bipolar plate facing away from the at least one electrode.

[0036] It is particularly useful to reduce deposits and / or air inclusions in the cells if the at least one bipolar plate is subjected to a low-frequency or high-frequency oscillation. Phases with low-frequency oscillations, phases with high-frequency oscillations, and / or phases without oscillations can alternate. The invention will be explained in more detail below with reference to a drawing that merely illustrates exemplary embodiments. The drawing shows:

[0037] Fig. 1 shows an electrochemical reactor according to the invention in a schematic sectional view transverse to the stacking direction of the cells of one cell stack,

[0038] Fig. 2 shows a bipolar plate for use in the electrochemical reactor according to Fig. 1 in a perspective view,

[0039] Fig. 3 shows an alternative bipolar plate for use in the electrochemical reactor according to Fig. 1 in a perspective sectional view and

[0040] Fig. 4 shows a bipolar plate for use in the electrochemical reactor according to Fig. 1 in a schematic, perspective view.

[0041] Fig. 1 shows an electrochemical reactor 1 in the form of a redox flow battery with a bipolar structure in a sectional side view. The electrochemical reactor 1 comprises a stack (cell stack Z) of individual cells 2 arranged next to one another in a stacking direction R. Between the individual cells 2, bipolar plates 3 are provided, which on one side rest against a negative electrode 5 of a cell 2 and on the opposite side rest against a positive electrode 6 of an adjacent cell 2. At the two opposite ends of the electrochemical reactor 1, an end plate 7, 8 is provided with internal, electrically conductive discharge plates 9, via which voltage can be tapped off and via which a 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 each other by a separator 10 arranged between the electrodes 5, 6. In the electrochemical reactor 1 shown, the two electrodes 5, 6 are each in contact with an electrolyte 11, 12. The electrodes 5, 6 are each accommodated in a cell frame 12 and are in direct contact with the adjacent bipolar plates 3. The cell frames 12 can be clamped together via an external clamping device. However, it is also possible to weld the cell frames 12 together, if necessary across the bipolar plates 3.

[0042] The bipolar plates 3 are connected to external activation devices designed to cause oscillators integrated into the bipolar plates 3 to oscillate. Various configurations of the bipolar plates 3 are possible, some of which are described below as examples.

[0043] Fig. 2 shows a bipolar plate 3 in which the oscillator 13 is accommodated in a matrix made of a thermoplastic material 14. The thermoplastic material 14 forms the continuous phase in which a filler 15, such as graphite or carbon black, and the oscillator 13 are accommodated as disperse phases. The bipolar plate 3 can then be set into oscillation, or more precisely, vibration, by applying a varying external voltage via an external activation device 16 in the form of a voltage source. The oscillations of the bipolar plate 3 are then transferred to other parts of the cell stack Z. In the case of a redox flow battery, the oscillations are also transferred in particular to the electrolytes 11, 12. The oscillator 13 is in particular, but not necessarily, a flexoelectric plastic or a piezoelectric.Alternatively or additionally, these oscillators 13 can also be integrated as a layer of the bipolar plate 3 or in the form of strips in the bipolar plate 3. The remainder of the bipolar plate 3 can then be formed from a mixture of thermoplastic 14 and electrically conductive filler 15. Fig. 3 shows a bipolar plate 3 with two outer bipolar plate parts 17, which enclose an interior space between them, which can be used as a fluid volume 18 for receiving a fluid 19 or a hydrogel. The fluid volume 18 is connected to an external activation device 16. The activation device 16 comprises a supply line 20 and a pump unit 21 for periodically supplying and removing fluid 19 to and from the fluid volume 18 of the bipolar plate 3 designed as a bipolar cushion 22. The oscillator 13 of the bipolar plate 3 is accommodated in the fluid volume 18.The bipolar plate parts 17 are electrically connected to one another directly and indirectly via the fluid 19 or the hydrogel.

[0044] Figure 4 shows a bipolar plate 3 with two outer bipolar plate parts 17, between which strips 23 made of a piezoelectric material 24, a magnetostrictive material, or a shape memory polymer are accommodated in the bipolar plate 3. The strips 23 are connected to an external activation device 16, which can apply a varying voltage, a varying magnetic field, or a varying temperature to the strips 23 to cause the bipolar plate 3 to oscillate.

[0045] List of reference symbols

[0046] 1 Electrochemical reactor

[0047] 2 cells

[0048] 3 bipolar plate

[0049] 5 Electrode

[0050] 6 Electrode

[0051] 7 End plate

[0052] 8 End plate

[0053] 9 arrester plate

[0054] 10 Separator

[0055] 11 Electrolyte

[0056] 12 Cell frame 13 Oscillator

[0057] 14 Plastic

[0058] 15 Filler

[0059] 16 Activation device 17 Bipolar plate part

[0060] 18 fluid volumes

[0061] 19 Fluid

[0062] 20 supply line

[0063] 21 Pump unit 22 Bipolar cushion

[0064] 23 stripes

[0065] 24 piezoelectric material

[0066] R Stacking direction

[0067] Z cell stack

Claims

Patent claims 1. Electrochemical reactor (1), in particular redox flow battery, fuel cell, electrolyzer or electrosynthesis cell, with a cell stack (Z) made of a plurality of cells (2) which are each separated from one another by at least one bipolar plate (3) and stacked in a stacking direction (R), wherein the cells (2) each have two electrodes (5, 6) and a separator (10) arranged between the two electrodes (5, 6), and wherein the at least one bipolar plate (3) is designed to be flexible, characterized in that an oscillator (13) which excites the at least one bipolar plate (3) to oscillate is integrated into the bipolar plate (3).

2. Electrochemical reactor according to claim 1, characterized in that the oscillator (13) is formed by at least one flexoelectric plastic, at least one hydrogel, at least one shape memory polymer, at least one piezoelectric and / or at least one magnetostrictive material.

3. Electrochemical reactor according to claim 1 or 2, characterized in that the oscillator (13) is coupled to an activation device (16) and that, preferably, the activation device (16) is designed for periodic voltage change, pressure change and / or temperature change of the oscillator (13).

4. Electrochemical reactor according to one of claims 1 to 3, characterized in that the oscillator (13) is formed by at least one inner fluid volume (18) of the bipolar plate (3) filled with a fluid (19), and in that the fluid volume (18) is connected via at least one supply line (20) to a fluid supply for the periodic supply and removal of fluid (19).

5. Electrochemical reactor according to one of claims 1 to 4, characterized in that the oscillator (13) is provided between at least two electrically conductively connected bipolar plate parts (17) and that, preferably, the at least two bipolar plate parts (17) form a bipolar cushion (22) with the oscillator (13) accommodated in the interior of the bipolar cushion (22).

6. Electrochemical reactor according to one of claims 1 to 5, characterized in that the at least one bipolar plate (3), the bipolar plate parts (17) and / or the bipolar cushion (22) are formed at least predominantly from a thermoplastic plastic (14) and an electrically conductive filler (15) and that, preferably, the thermoplastic plastic (14) contains at least predominantly polyethylene and / or polypropylene and / or the filler (15) contains at least predominantly a carbon-containing material, such as graphite, carbon black or carbon nanotubes.

7. Electrochemical reactor according to one of claims 1 to 6, characterized in that the at least one oscillator (13) is an integral component of the bipolar plate (3), the bipolar plate parts (17) and / or the bipolar cushion (22) and that, preferably, the oscillator (13) is a disperse phase in a continuous Phase comprising a thermoplastic material (24) and a filler (15).

8. Electrochemical reactor according to one of claims 1 to 7, characterized in that the at least one separator (10) and / or the two electrodes (5, 6) of the cells (2) are accommodated in a cavity of at least one cell frame.

9. A method for operating an electrochemical reactor (1) according to one of claims 1 to 8, wherein the at least one oscillator (13) is excited to oscillate at least in phases and wherein the oscillator (13) causes the at least one bipolar plate (3) to oscillate.

10. The method according to claim 9, wherein the at least one bipolar plate (3) is designed in the form of a volume-variable bipolar cushion (22), wherein the volume of the bipolar plate (3) is varied by supplying and removing fluid (19) into the bipolar plate (3) and wherein the electrolyte (11) is pressed out of at least one half-cell by supplying fluid (19) and / or is sucked into at least one half-cell by removing fluid (19).

11. The method according to claim 10, wherein the transport of the at least one electrolyte (11) through the at least one half-cell is effected exclusively by the supply and removal of fluid (19) into and out of the at least one bipolar plate (3).

12. Method according to one of claims 9 to 11, in which at least one electrolyte (11) of the electrochemical reactor (1) is brought into contact exclusively with the at least one thermoplastic material (14) and / or with the filler (15) of the bipolar plate (3).

13. Method according to one of claims 9 to 12, wherein the at least one bipolar plate (3) is subjected to a low-frequency or high-frequency oscillation.

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