Electrolysis cell or electrode plate with a gas diffusion electrode, and method for operating same

Abstract

The invention relates to an electrolysis cell with a gas diffusion electrode (16), to an electrode plate (16, 25) which comprises a gas diffusion electrode and can be used in such an electrolysis cell, and to a method for operating such an electrolysis cell. The gas diffusion electrode (16) separates an electrolyte chamber (13, 14) from a gas chamber (27, 28), and the gas chamber is provided with a reaction gas which is converted in the gas diffusion electrode (16). According to the invention, the gas chamber has first channels (27) and second channels (28) which run separately such that the reaction gas must pass through the gas diffusion electrode (16) laterally in order to reach the second channels (28) from the first channels (27). This can be supported by applying a pressure difference, whereby an additional setting possibility for the parameters of the ongoing electrolysis reaction is advantageously provided. The gas diffusion electrode (16) can be used together with a support element (25), which receives the first channels (27) and the second channels (28) and supports the gas diffusion electrode (16), as a bipolar electrode plate (16, 25) in a stacked structure of the electrolysis cell.

Description

[0001] Description

[0002] Electrolysis cell or electrode plate with a gas diffuser ¬ On electrode and methods for its operation

[0003] The invention relates to an electrolysis cell comprising a housing with an anode and a gas diffusion electrode (hereinafter also referred to as GDE) connected as the cathode. Both electrodes can be exposed to an electrolyte in an electrolyte chamber formed by the housing. The GDE acts as a partition between the electrolyte chamber and a gas space provided in the housing for a reaction gas. The GDE borders the electrolyte chamber on one electrolyte side and the gas space on one gas side, thus separating these two spaces. The invention also relates to a

[0004] Electrode plate, which in the aforementioned electrolysis cell ¬ can be set.

[0005] Furthermore, the invention relates to a method for operating such an electrolysis cell of the type mentioned above. In this method, the electrolyte side of the GDE is treated with a ¬ an electrolyte is applied and the gas side of the GDE is treated with a ¬ nem reaction gas. Electrolysis cells with electrode plates of the type described above and methods for their operation are generally known. Gas diffusion electrodes are used, for example, in

[0006] Gas generators (GDEs) are used in fuel cells to generate energy from hydrogen and oxygen. Another application of GDEs is in electrochemical cells for the conversion of reaction gases. In such electrochemical cells, a reactant gas (reaction gas) is supplied and a product gas, which can also be a gas mixture, is discharged. The GDE forms the cathode, which is designed to be gas-permeable (microporous structure). The electrolyte space between the anode and cathode is filled with an electrolyte and may also contain a separating membrane, for example, made of Nafion®. In this case, the electrolyte is supplied separately to the two compartments. ¬ leads .

[0007] The GDE enables the diffusion of the reaction gas, which can be supplied to the cathode in this way. To allow the gas to penetrate the cathode, the con ¬The centrifugal gradient, which arises from the ongoing conversion of the gas inside the GDE, is exploited. A further ¬ Another possibility is to increase the gas pressure on the gas side of the GDE, thereby increasing the gas turnover in the GDE.

[0008] The reaction gas is converted in the gas pressure accumulator (GDE). This can produce a product gas which, depending on the pressure on the gas side, can penetrate the GDE and be transported out of the electrolyte chamber with the electrolyte, or it can escape into the gas chamber and be carried away there. ¬ ported. In the latter case, a continuous gas flow is necessary in the gas space, whereby reaction gas is supplied and a mixture of reaction gas and product gas is discharged.

[0009] Operating the electrolysis cells described above therefore consists of supplying the reaction gas as a reactant, introducing it into the gas discharge unit (GDE), and subsequently removing the reaction gas or any resulting product gas. The possibility ¬ The possibilities of influencing this process through diffusion processes in the gas-to-electrolyte enclosure (GDE) and through pressure differences between the gas and electrolyte sides of the GDE are limited. The pressure difference allows gas to be forced through the porous GDE. However, this also requires consideration of uneven pressure. ¬ Desired effects must be accepted. Depending on the pressure differential, reaction gas may also escape from the gas-side gas generator (GDE). Conversely, the electrolyte may escape from the gas-side of the GDE. Since this is usually a salt solution, there is a risk of salts crystallizing on the gas-side of the GDE. Furthermore, the escaping liquid must be removed from the gas space and... ¬This may humidify the reaction gas. The object of the invention is to provide an electrolysis cell with a gas diffusion electrode, a component in this electrolysis ¬ to specify a cell-usable electrode plate and a method for its operation, with which the gas throughput of reaction gas in the GDE can be adjusted as flexibly as possible, while minimizing unwanted throughput of electrolyte and / or reaction gas through the GDE as much as possible. ¬ is avoided.

[0010] This task will be accomplished using the electrolysis method described at the beginning. ¬ The cell is solved according to the invention by the fact that the gas diffusion ¬ The electrode (GDE) is connected with its gas side to a contact side of a support body, the gas space being formed by a first channel system and a second channel system. The first channel system and the second channel run parallel to each other. ¬The systems are separate from each other, meaning that the reaction gas cannot directly move between the first and second channel systems. Instead, the first and second channel systems each have openings in the contact area. ¬ The side opens up, directly adjacent to the gas side of the GDE. This advantageously ensures that the reaction gas flows through the GDE to switch between the first and second channel systems. This forces a flow of the reaction gas through the GDE, whereby this la ¬ The pipeline runs along the gas side of the GDE. This creates additional possibilities for controlling the gas flow in the GDE. ¬ ern. Because the first canal system and the second canal ¬Since the two systems are separate, it is possible to set different pressures in each system. This creates a controllable pressure gradient that directly influences the flow of the reaction gas in the gas discharge unit (GDE). Increasing the pressure difference leads to... ¬ Primarily leads to an increase in the reaction gas flow laterally to the gas side of the GDE and only indirectly to an increase in the flow ¬ The reaction gas flows orthogonally to the gas side. Therefore, even with high pressure differences between the first and second channel systems, it is easier to prevent or at least reduce the passage of the reaction gas to the electrolyte chamber. The pressure difference can also be increased during ¬The operation of the electrolysis cell can be modified. On the other hand, regardless of the pressure gradient between the first and second channel systems, the pressure gradient between the gas side and electrolyte side of the GDE can be adjusted to optimize the orthogonal component of the reaction gas flow on the one hand and the electrolyte flow orthogonal to the electrolyte side in the direction of the

[0011] to influence the gas space. Advantageously, this can prevent or at least minimize the passage of electrolyte at the GDE. ¬ can be changed without increasing the flow rate of the reaction gas. ¬ to significantly influence. Of course, other influencing factors can also be varied. The thickness of the GDE, the layer structure and its porosity can, for example, be adjusted. ¬The support structure can be modified to influence the flow conditions within the gas discharge unit (GDE). Furthermore, the support structure contributes advantageously to the mechanical and electrical contacting of the GDE. This facilitates the production of large-area GDEs because they can be reliably electrically contacted and mechanically stabilized via the support structure. The mechanical stabilization, in turn, allows for larger pressure differentials between the gas and electrolyte sides of the GDE, which further increases the flexibility in adjusting the process parameters. The reaction gas can be directed from the first channel system into the GDE via the openings and from the GDE into the second channel system via the openings. However, the reverse direction is also conceivable.According to the method described above, it is also possible, according to the invention, to reverse the flow direction of the reaction gas at least once during electrolysis in the first channel system, on the gas side, and in the second channel system. Thus, the first channel system and the second channel system can each be used for both supplying the reaction gas and for discharging the reaction gas and any product gas that may have been generated. Reversing the flow direction during electrolysis has the advantage that performance losses of the gas discharge unit (GDE) that can occur due to the establishment of a steady state in the GDE can be compensated for.

[0012] Adjusting the respective pressure differentials between the first and second channel systems and between the electrolyte and gas sides of the GDE can also be used to... ¬This is used to control the path of a product gas generated in the GDE. Because the product gas passes through other areas... ¬ exhibits properties other than the reaction gas (which is considered

[0013] (where reactant gas is fed in) it is possible that the product gas passes through the GDE and, via the electrolyte space, the electrolyte. ¬ The process can be influenced by adjusting the pressure between the first and second channel systems, as well as between the electrolyte and gas sides of the gas discharge unit (GDE).

[0014] The task is also completed by the electrical system mentioned at the beginning. ¬The electrode plate is solved by attaching the gas diffusion electrode with one gas side to a contact side of a plate-shaped support body, wherein a gas space adjacent to the gas side is formed by a first channel system and a second channel system. The first and second channel systems run separately from each other, as already described. Furthermore, the first and second channel systems each have openings in the contact side to which the GDE is attached. Such an electrode plate is used for installation in the electrolysis cell described above, where ¬ through the advantages already described.

[0015] According to one embodiment of the electrode plate according to the invention, one side of the support body opposite the contact side is electrically conductive and is in electrical connection with the contact side. This allows the electrode plate to be used as a bipolar plate, which advantageously results in a particularly simple design of the electrode plate. ¬ This enables the use of a stacked electrolysis cell. Electrolyte chambers alternate with the fluid from the first channel system. ¬ The gas spaces formed by the first and second channel systems are arranged, with the gas space being integrated into the electrode plate. The electrode spaces are located between the electrode plates, preferably separated into an anode space and a cathode space by a separating membrane. Each electrode plate serves with the gas space attached to one side of it. ¬The closed GDE acts as the cathode and, in an adjacent electrolyte chamber, with its opposite side acting as the anode. The contact side of the support body simultaneously serves for the electrical contact of the GDE.

[0016] Another possibility is that both sides of the support body are designed as contact surfaces for one GDE each. This means that the first channel system and the second channel system must also have openings on both contact surfaces. In this way, the electrode plate can be positioned before ¬ This serves, in part, to provide one GDE as a cathode for each of two adjacent electrode spaces. According to further embodiments of the electrode plate according to the invention, as explained above, the electrode plate can be made of... ¬be designed in such a way as to achieve the advantages already explained. In particular, it is possible for the first channel system to have first channels and the second channel system to have second channels, with the first channels and the second channels being ¬ The channels are arranged alternately and parallel to each other and parallel to the contact side within the support body. It is particularly advantageous if the first channel system and the second channel system are comb-like and interlock. It is also advantageous if the openings in the contact side are open towards the contact side. ¬ a first channels and the two open towards the contact page ¬ten channels are formed. Alternatively, the openings in the contact side are formed by holes that connect the first channel system and the second channel system to the contact side. According to an advantageous embodiment of the electrolysis cell according to the invention, the electrolyte space is divided into an anode space and a cathode space by a partition wall designed as an ion-permeable membrane or as an ion- and liquid-permeable, separate partition wall, wherein the anode space has an anolyte inlet and an anolyte outlet for an anolyte and the cathode space has a catholyte inlet and a catholyte outlet for a catholyte. Such a design of the electrolyte space is advantageous if different gases are generated at or pass through the anode and the cathode (GDE), which are in the

[0017] The electrolyte compartment should not be mixed. The partition is of particular importance if an electrolyte is present in the electrolyte compartment. ¬ lysis of water takes place and the resulting gases oxygen and hydrogen should not mix to form an explosive mixture.

[0018] According to a further embodiment of the invention, the first channel system comprises first channels and the second channel system comprises second channels, wherein the first and second channels are arranged alternately and parallel to each other and parallel to the contact side within the support body. The parallel arrangement advantageously ensures that the distances between the first and second channels remain constant and can be designed according to the criterion that a required path ¬ The gas travels a certain distance within the GDE. The reaction gas flows from the Ka used as inlet points. ¬The channels are connected to the outlet channels. A parallel alignment of the channels to the contact side advantageously further supports the uniform distribution of the reaction gas across the entire gas discharge unit (GDE), whose surface rests against the support body via the contact side. In addition to accommodating the channels and distributing the reaction gas, the support body advantageously also supports the GDE. Therefore, the GDE can be made thinner or have a greater porosity and thus a larger internal surface area for the reaction gas conversion. ¬ The efficiency of the gas delivery system (GDE) is advantageously increased, while the mechanical stability of the GDE is ensured by the support body. The areas of the contact side that are not provided with openings and thus lie directly against the gas side of the GDE are sufficient for this purpose.

[0019] If the support body is made of an electrically conductive material, it can be used according to a further advantage. ¬ In a further embodiment of the invention, the electrical contacting, and not just the mechanical contacting, of the GDE can also be achieved. Particularly with large-area GDEs designed for large-scale industrial use, this method allows for electrical contacting of the GDE with low contact resistance. The support body is also particularly suitable for creating a stacked structure of the

[0020] to support the electrolysis cell (more on this below).

[0021] A special configuration of the channel arrangement is obtained when the first channel system and the second channel system are comb-like and interlock. The Ver ¬ The course of the channels corresponds to the teeth of the comb, each of which is supplied via a common distribution channel. ¬The distances between the adjacent channels of one comb-like arrangement are so large that the adjacent channels of the other comb-like arrangement can fit into the spaces between them. The distance between the first and second channels is each so large that the reaction ¬The reaction gas travels a sufficient distance in the adjacent GDE. The advantage of a comb-like design of the channel system is a flow-optimized configuration in which the individual first and second channels can be uniformly supplied with the reaction gas. This can be further supported by a tapered cross-section towards the ends of the respective first and second channels. Another embodiment of the invention provides that the openings in the contact side are formed by the first channels and the second channels, which are open towards the contact side. In other words, the channels in the contact side are designed as grooves or troughs, so that, in other words, the missing wall of the channels forms the opening in the contact side. This has the advantage that the opening has a sufficiently large cross-sectional area, since ¬so that the reaction gas can exchange between the respective channels and the GDE with low flow resistance. The remaining contact surface between the channels serves as the ¬ This design allows the GDE to be supported by the support body.

[0022] Yet another embodiment of the invention provides that the openings in the contact side are formed by holes that connect the first channel system and the second channel system to the contact side. In other words, the first channels and the second channels are designed in such a way that ¬ This results in them running inside the supporting body, where ¬ The holes create connections through which the reaction gas can flow from the channels into the GDE and from the GDE back into the channels. In this embodiment, a comparatively large surface area of ​​the con is advantageously available. ¬ The timing side is available for supporting the GDE by the support body.

[0023] According to a particularly advantageous embodiment of the electrolysis cell, at least two electrolyte chambers are arranged in the housing. Preferably, significantly more than two electrolyte chambers can be provided, for example, ten, twenty, or fifty electrolyte chambers. A stacked design is understood to mean a construction in which the electrolyte chambers are each ¬ because it is arranged alternately with the electrodes (i.e., the anode and the GDE designed as the cathode) and the gas spaces, whereby in particular in large-scale applications sufficient ¬ A sufficient electrode surface area can be provided in a comparatively small installation space. The design of the stacked electrolysis cell can vary, as will be explained below.

[0024] According to a stacked design of the electrolysis cell ¬It is wisely provided that adjacent electrolyte compartments are separated from each other by a support body that rests on both

[0025] Each side has a contact surface, on which there is a gas diffuser. ¬ sion electrode adjacent to. This means that on both sides ¬ A gas discharge unit (GDE) must be arranged in the support body, with the first channel system and the second channel system in the support body each supplying both GDEs with the reaction gas. The following applies: ¬ the adjacent electrode spaces point to the opposite one ¬ On each side of the GDE, there is then a preferably plate-shaped anode, which also borders a cathode compartment on both sides. In the stacking sequence, there is therefore a cathode compartment, a GDE-

[0026] Supporting body assembly, a cathode space, an anode, a catho ¬The space, a GDE support body composite, etc. The advantage of this design is that the support bodies are subjected to the pressure of the reaction gas symmetrically and the number of support bodies used can be reduced.

[0027] According to another embodiment of the invention, adjacent electrolyte spaces are provided for by a support body of ¬ are separated from each other, with the gas diffusion electrode of one of the adjacent electrode spaces attached to the contact side. ¬ borders and its opposite side as the anode of the ¬whose adjacent electrode compartments are formed. In this way, a bipolar plate is created, which serves as the anode for one electrolyte compartment on one side and is equipped with the channel system and the gas-electrode unit (GDE) for an adjacent electrolyte compartment on the other side. In this stacked design, the electrolyte compartments alternate with the cathode-anode unit (comprising the support body with the gas space and the GDE), resulting in a particularly simple structure. In particular, the electrical contacting is simplified, since the bipolar plate ¬ ten can be electrically connected in series, which is why an electrical connection to a voltage source is only possible one at a time. ¬ Because it must occur at the outermost anode and the outermost cathode formed by a support plate and a GDE. For this purpose, the support elements must be electrically conductive.

[0028] Further details of the invention are described below with reference to the drawing. Identical or corresponding drawing elements are represented by the same reference numerals. ¬ The figures are provided with additional information and are only explained more frequently to the extent that differences arise between the individual figures. They show: an electrolysis cell in a setup according to the prior art, a composite of support body and GDE as it can be used in an embodiment according to the prior art, Figure 3

[0029] and 4 embodiments of the invention

[0030] Electrolysis cell in cross-section, wherein, according to Figure 3, an embodiment of the invention is shown. ¬ the procedure is carried out and

[0031] Figure 5

[0032] and 6 examples of designs for support bodies in

[0033] Section showing different configurations of the first and second channels that can be used in the electrolysis cell according to the invention. Figure 1 shows a prior art electrolysis cell. An electrolyte is contained in a housing 11. ¬ A space is provided which is divided by a gas-impermeable partition 12 into an anode compartment 13 and a cathode compartment 14. The electrolyte space is thus jointly formed by the anode compartment 13 and the cathode compartment 14. The anode compartment 13 is further bounded by an anode 15 and the cathode compartment 14 by a gas diffuser connected as a cathode. ¬ ion electrode (GDE) 16. To pass through the anode space

[0034] To allow the passage of anolytes (A), an anolyte inlet 17 and an anolyte outlet 18 are provided. Likewise, the

[0035] Catholic dream 14 a Catholic entrance 19 and a

[0036] Catholyte outlet 20 opens to allow the passage of a catholyte (K).

[0037] The GDE 16 borders the electrolyte side 21.

[0038] Catholyte chamber 14. With a gas side 22 opposite the electrolyte side 21, the GDE 16 borders a gas chamber 23, which is also housed in the casing 11. This gas chamber 23 has a gas inlet 24 for a reaction ¬ onsgas, which can diffuse into the GDE 16 due to its porosity (indicated in Figure 1).

[0039] Figure 2 shows the GDE 16 in its inventive arrangement on a support body 25. This support body is shown in section II-II according to Figure 5, where Figure 5 is shown in section VV (drawn in Figure 2). The support body 25 has a contact side 26 on which the GDE 16 rests with its gas side 22. First channels 27 and second channels 28 are also provided in the contact side 26. ¬see. The first channels 27 and second channels 28 differ. ¬ The difference lies in the fact that the first channels belong to a first channel system 29 and the second channels to a second channel system 30 (see Figure 5), with the first channel system being fluidically separated from the second channel system. This divides the gas space into two separate volumes. As can be seen in Figure 5, the first channel system can be used to supply the reaction gas, as indicated by the arrows shown with solid lines. ¬ the second channel system 30 for the removal of reaction gas not consumed during the reaction. ¬ The reaction gas changes as it passes through the Po ¬The passage in GDE 16 from the first channel system to the second channel system is also indicated by the arrows. These arrows thus indicate a passage through GDE 16, although GDE 16 is not shown in Figure 5. ¬ During the passage through the GDE 16, the reaction gas is at least partially ¬ This is implemented as part of a reaction (see also the arrows in Figure 2). The dashed arrows in Figure 5 indicate that the flow direction in the support body can also be reversed, causing the GDE 16 to flow through in the opposite direction.

[0040] The unit shown in Figure 2 forms an electrode plate, which ¬ which can be used for installation in the housing of an electrolysis cell. An example of such an installation can be seen in Figure 3. ¬ take. In this process, the electrode plate forms a bipolar plate according to Figure 2, i.e., that the contact side 26 faces ¬The anode 15 is located on the opposite side of the support body 25. ¬ This leads to... If the electrode plate according to Figure 2 is installed in a stacked electrolysis cell, the ano ¬ The electrolyte 15 and the cathode formed by the electrolyte 16 are each placed in adjacent electrolyte compartments (see also Figure 3). For the electrolyte cell according to the invention, fundamentally different construction principles are possible, which are exemplified by... ¬ are shown in Figure 3 and Figure 4. Both are shown. ¬ The arrangements show possible stacking designs of the electrolysis cell.

[0041] According to Figure 3, electrode plates with a structure as shown in Figure 2 are used. The following stacking sequence is implemented in the electrolysis cell. The support body 25 is followed on the side that serves as the anode 15 by an anode. ¬Space 13, which is separated from a subsequent cathode space 14 by a partition wall 12. Adjacent to the cathode space 14 is a GDE 16, which is supported by a subsequent support body 25. First channels 27 and second channels 28 are also formed in the support bodies 25. The stacking sequence then repeats.

[0042] For the anode compartments 13 there are anolyte inlets 17 and anolyte outlets 18 each, as well as those for the cathode compartments.

[0043] Catholyte entrances 19 and catholyte exits 20 are provided. ¬ Furthermore, a connecting nozzle 31 can be seen, which is connected to the first channels 27 in a manner not shown in detail. In the flow direction shown in Figure 3, the connecting nozzle is used as a gas inlet, in which the gas is drawn through the gas flow. ¬The dashed arrows indicate the reverse flow direction as the gas outlet for the reaction gas with which the GDE is supplied. A comparable connection nozzle for the second channels 28 is located in front of the plane of the drawing shown in Figure 3 and is therefore not shown.

[0044] Furthermore, the electrical contacting of the electrolysis cell is indicated in Figure 3. The design of the connection ¬ The electrolysis cells, consisting of the respective anode compartments 13 and cathode compartments 14, are connected in series using the support body 25 and the GDE 16, each as a bipolar plate. Only the outermost anode of the stack is connected to the positive terminal of a voltage source, and the outermost GDE is connected to the negative terminal of the voltage source 32 via the outermost support body.

[0045] Figure 4 shows a similar structure to that described in Figure 3, although only the differences will be explained below. The support body 25 has two opposing contact sides 26, each with a GDE 16 arranged on it. This results in the following stacking sequence for the stacked construction. An electrode plate is provided as the anode 15, to which an anolyte chamber 13 adjoins. This is separated from a catholyte chamber 14 by a partition 12. This is followed by a GDE 16, which is mounted on a support body 25. ¬ is needed. On the other side of the support body 25 is located ¬ Another GDE 16 is added. This is followed by another cathode chamber 14, another partition 12 and another anode chamber 13. The stacking sequence then begins again with another anode 15.

[0046] In this arrangement of electrolysis cells, consisting of anode compartment 13 and cathode compartment 14, these are connected in parallel. Therefore, there is an electrical connection between all anode compartments. ¬ The 15 and all GDE 16 are each connected via the support bodies 25. This is indicated in Figure 4. As can be seen, the positive terminal of the voltage source 32 is connected to the anodes 15 and the negative terminal of the voltage source 32 to the electrically conductive ¬ The supporting bodies are electrically connected 25 times.

[0047] The first channels 27 and second channels 28 are at the

[0048] The support body 25, as shown in Figure 4, is designed such that it opens on both sides. The first channels 27 and second channels 28 thus simultaneously supply both opposing GDE 16 with the reaction gas. The fluidic connections (17, 18, 19, 20, 31) of the electrolysis ¬The cells show no differences from the structure shown in Figure 3 and are therefore not explained in more detail in connection with Figure 4.

[0049] A possible course of the first canal system 29 and the second canal system 30 can be seen in Figure 5. Both canal systems have a comb-like course, which means ¬ The first channels 27 and the second channels 28 form the teeth of this comb-like arrangement. These run alternately parallel to each other, which is achieved by the interlocking of the comb-like structures. Furthermore, the first channels 27 and the second channels 28 are also arranged parallel to the depicted plane, so that they are also parallel to the plane above it. ¬ The contact side 26 (see Figure 2) runs parallel to the first channels 27 and the second channels 28, as can be seen in Figure 2. ¬Constant distance that the reaction gas conveyed through the aforementioned channels must travel in GDE 16 to move from the first channel system 29 to the second channel system 30 (or vice versa). This ensures a uniform load. ¬ The impact of the GDE with reaction gas causes the gas to... ¬ The flow runs primarily parallel to the gas side 22 of the GDE 16. An escape of the reaction gas from the electrolyte side ¬ This makes it easier to prevent the 21st minute of GDE 16.

[0050] As can be seen in Figure 5, the first channel ¬ system 29 and the second channel system 30 one

[0051] The cross-sectional profile decreases steadily towards the dead ends of the first channels 27 and second channels 28. This ensures a uniform pressure distribution of the reaction gas in the aforementioned channel system, so that the local pressure gradient between the openings of the first channels 27 and second channels 28 can be kept constant across the area of ​​the GDE 16.

[0052] Figure 6 shows an alternative embodiment of the support body 25, in which the openings in the contact side are formed by holes 33. The holes can, for example, be bores that connect the first channels 27 and second channels 28 to the contact side of the support body 25, which, according to Figure 6, lies behind the plane of the drawing. ¬The first channels 27 and second channels 28 run diagonally in the illustrated square cross-section of the support body 25 in the embodiment shown in Figure 6. The holes 33 are arranged in the support body 25 on a square grid, so that adjacent holes ¬ each of the first channels 27 is also alternately connected to one of the second channels 28. This creates short paths for the reaction gas in the GDE lying behind the plane of the drawing, as indicated by the vertical and horizontal arrows shown in Figure 6, specifically from one of the holes 33 to the four vertically and horizontally adjacent holes 33.

[0053] To connect the first channels 27 and the second channels 28 to form a first channel system 29 and a second channel system 30, respectively, said channel systems are continued and combined in the housing surrounding the support body (not shown in detail). The course of the first channel 27 ¬ The first canal system 29 and the second canal system 30 are indicated at the edge of the support body with dashed lines.

[0054] An example of the application of the electrolysis cell is shown in Figure 1 and can be applied in the same way with the ge ¬ The reaction is carried out in electrolyte cells designed according to Figures 2-6. Carbon dioxide is used as the reaction gas, which ¬ ches is converted to carbon monoxide in GDE 16. The carbon monoxide preferentially passes through the GDE on the electrolyte side. ¬ page 21 and is connected with the passed catholyte (K) from ¬The hydrogen gas is transported. Due to the electrochemical splitting of water, hydrogen is also produced in the cathode compartment 14, which is then discharged along with the carbon monoxide. Oxygen is produced in the anode compartment 13. The partition 12 prevents the hydrogen gas from mixing with the oxygen. ¬ gas mixes.

[0055] In contrast to the device shown in Figure 1, in the electrolysis cells according to Figures 2-6, the carbon dioxide is fed in via one of the two channel systems (first channel system 29, second channel system 30) and unreacted carbon dioxide gas is carried out through the other of the two channel systems (29, 30). ¬the carbon dioxide is discharged. This creates the possibility of adjusting the pressure difference between the two aforementioned channel systems and using it as a control parameter for the carbon dioxide flow rate in the GDE 16. The discharged carbon dioxide gas may also contain carbon monoxide gas that has not penetrated to the electrolyte side 21 of the GDE 16.

Claims

1.         An electrolysis cell comprising a housing (11) with an anode (15) and a gas diffusion electrode (16) connected as cathode, which can both be brought into contact with an electrolyte in an electrolyte space formed by the housing (11), where · the gas diffusion electrode (16) is arranged as separator between the electrolyte space and a gas space for a reaction gas provided in the housing (11) and · the gas diffusion electrode adjoins on an electrolyte side (21) the electrolyte space and on a gas side (22) adjoins the gas space, characterized in that the gas diffusion electrode (16) adjoins on the gas side (22) a contact side (26) of a support body (25), where the gas space is formed by a first channel system (29) and by a second channel system (30), where · the first channel system (29) and the second channel system (30) run separately from one another and thus form two separate volumes of the gas space and · the first channel system (29) and the second channel system (30) each have openings in the contact side (26). 2.         The electrolysis cell as claimed in claim 1, characterized in that the electrolyte space is divided by a dividing wall (12) configured as ion-permeable separation membrane or as ion- and liquid-permeable separator into an anode space (13) and a cathode space (14), where the anode space (13) has an anolyte inlet (17) and an anolyte outlet (18) for an anolyte and the cathode space has a catholyte inlet (19) and a catholyte outlet (20) for a catholyte. 3.         The electrolysis cell as claimed in claim 1 or 2, characterized in that the first channel system (29) has first channels (27) and the second channel system (30) has second channels (28), with the first channels (27) and the second channels (28) being arranged alternately and parallel to one another and to the contact side (26) in the support body (25). 4.         The electrolysis cell as claimed in claim 3, characterized in that the first channel system (29) and the second channel system (30) have a comb-like configuration and intermesh. 5.         The electrolysis cell as claimed in claim 3, characterized in that the openings in the contact side (26) are formed by the first channels (26) which are open in the direction of the contact side (26) and the second channels (28) which are open in the direction of the contact side (26). 6.         The electrolysis cell as claimed in claim 3, characterized in that the openings in the contact side (26) are formed by holes (33) which connect the first channel system (29) and the second channel system (30) in each case to the contact side (26). 7.         The electrolysis cell as claimed in claim 1, characterized in that at least two electrolyte spaces are arranged in the housing (11). 8.         The electrolysis cell as claimed in claim 7, characterized in that adjacent electrolyte spaces are separated from one another by a support body (25) which on both sides has a contact side (26) which is in each case adjoined by a gas diffusion electrode (16). 9.         The electrolysis cell as claimed in claim 7, characterized in that adjacent electrolyte spaces are separated from one another by a support body (25) which on its contact side (26) is adjoined by the gas diffusion electrode (16) of one of the adjacent electrode spaces and the opposite side of which is configured as anode (15) of the other of the adjacent electrode spaces. 10.       The electrolysis cell as claimed in claim 1, characterized in that the support body (25) consists of an electrically conductive material. 11.       An electrode plate having a gas diffusion electrode (16) for installation in an electrolysis cell as claimed claim 1 , characterized in that the gas diffusion electrode (16) is fastened on a gas side (22) to a contact side (26) of a plate-like support body (25), where a gas space adjoining the gas side (22) is formed by a first channel system (29) and by a second channel system (30), where · the first channel system (29) and the second channel system (30) run separately from one another and thus form two separate volumes of the gas space and · the first channel system (29) and the second channel system (30) each have openings in the contact side (26). 12.       The electrode plate as claimed in claim 11, characterized in that a side of the support body (25) opposite the contact side (26) is electrically conductive and is electrically connected to the contact side (26). 13.       The electrode plate as claimed in claim 11, characterized in that both sides of the support body (29) are configured as contact sides for in each case a gas diffusion electrode (25). 14.       A method for operating an electrolysis cell as claimed in claim 1, where the electrolyte side (21) of the gas diffusion electrode (16) is brought into contact with an electrolyte and the gas side (22) of the gas diffusion electrode (16) is supplied with a reaction gas, characterized in that the flow direction of the reaction gas in the first channel system (29), on the gas side (22) and in the second channel system (30) is reversed at least once during the electrolysis.

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