Contaminant trap in an electrolysis cell

Abstract

The present invention relates to an electrolysis cell with a contaminant trap, an electrolysis cell system, a vehicle comprising an electrolysis cell system and a method for cleaning an electrolysis cell.

Description

The invention relates to an electrolysis cell having the features of independent claim 1, an electrolysis cell system having the features of independent claim 10, a vehicle having the features of independent claim 11 and a method having the features of independent claim 12.Prior ArtElectrolysis cells, also referred to as electrolysers, are known which, combined in a stack, form an electrolysis system. By means of such an electrolysis cell or an electrolysis cell system, a reactant, for example water, can be chemically converted into products such as preferably hydrogen (H 2) and oxygen (O 2). This is done by supplying energy to the system, which can be brought about by electric current. The products are in turn suitable, inter alia, for the operation of a fuel cell.The devices from the prior art rely on as pure water as possible. This must meet higher requirements than ordinary drinking water in order to be able to operate an electrolysis cell. For this purpose, it is known to use a separate cleaning device to clean water, such as drinking water, for the purpose of further increasing its purity. Such a cleaning device is connected upstream of the electrolysis cell, so that water is (directly) cleaned before being fed into the electrolysis cell. However, even water purified in this (or other) manner contains residual impurities. These may result in reduced efficiency, reduced power, and / or time-varying power (i.e., not constant over time). Furthermore, impurities can lead to blockages, as a result of which a uniform flow is at least partially prevented, the longevity or usability is reduced and / or the safety is reduced, in particular if an electrolysis cell runs hot, for example as a result of a blockage or a build-up of a reactant or product. As a result, an electrolysis cell and / or an electrolysis cell system can be destroyed at least partially, and in the worst case completely, which can entail costs and / or safety risks for humans.The object of the present invention is therefore to provide an improved electrolysis cell, an improved electrolysis cell system, an improved vehicle and a method for cleaning an electrolysis cell, which at least partially overcomes the disadvantages from the prior art.The above object is achieved by an electrolytic cell having the features of independent claim 1, by an electrolytic cell system having the features of independent claim 10, by a vehicle having the features of independent claim 11 and by a method having the features of independent claim 12. Features and details which are described in connection with the electrolysis cell according to the invention naturally also apply here in connection with the electrolysis cell system according to the invention and / or in connection with the vehicle according to the invention and / or in connection with the method according to the invention and vice versa, so that with regard to the disclosure reference is or can always be made reciprocally to the individual aspects of the invention.The above object is achieved according to a first aspect of the invention by an electrolysis cell, wherein the electrolysis cell comprises (in particular along an x-direction in an x-y-z righthand system): an inlet side with a water inlet for feeding water, a first distribution region adjoining the inlet side, an active region adjoining the first distribution region, a second distribution region adjoining the active region, an outlet side adjoining the second distribution region. Furthermore, the electrolysis cell (in particular along a z-direction in an x-y-z righthand system) comprises a membrane electrode unit which is arranged between two bipolar plates, wherein the membrane electrode unit has two electrodes comprising an anode and a cathode, between which a membrane is arranged, wherein the electrolysis cell has at least one impurity scavenger in order to at least temporarily bind impurities from the fed water. The electrodes can have a catalyst or a catalyst coating in order to promote reaction processes, wherein this advantageously has platinum.In regular electrolysis operation (i.e. during electrolysis), the electrolysis cell can be flowed through in a flow direction, in particular by the starting materials and / or products, as described below. On the inlet side of the electrolysis cell, the water used for the electrolysis can be fed in as reactant. Further educts can be included, for example the at least temporary feeding of a cleaning agent for removing impurities in the at least one impurity scavenger is conceivable. In this case, feeding can take place via lines or so-called input ports. The water fed in (including any further educts) is conducted over a first distribution region, wherein in particular a distribution of the water fed in can take place, advantageously over the entire width (along y-direction), in particular of the active region, of the electrolysis cell. Subsequently, the water is guided into an active area, in which the electrolysis of the water preferably takes place, with the aim of producing the products hydrogen, oxygen and / or waste water. The wastewater can be considered here to be the water fed in during one pass through the electrolysis cell and unconverted (reacted). The products can leave the active region via a second distribution region, wherein the latter can be designed in particular to separate and / or combine the products at least partially from one another. The products can then be led out of the electrolysis cell at least partially via the outlet side, for example in order to be stored separately and / or to be supplied directly to a further device, such as a fuel cell, for example. The output side can have lines or so-called output ports. In this case, the water fed in can advantageously be used simultaneously as coolant. While the water fed in during electrolysis operation of the electrolysis cell flows through the latter in the direction of flow, cooling is effected in this case by removal of heat arising via the outlet side, it being possible for the water fed in to heat up. Furthermore, it may be that only a comparatively small proportion of water, for example 10% of the volume, is caused to electrolyze, while the remainder leaves the electrolysis cell via the water outlet.Impurities can be free radicals, minerals and / or particles and the like included in the water fed in within the scope of the invention, which free radicals prevent and / or impair, in particular, the electrolysis operation of an electrolysis cell, for example by aggregating them to form blockages and thus causing the electrolysis cell to damage or even to heat up, which can lead to complete destruction of the electrolysis cell and / or of the electrolysis cell system. Damage to the membrane electrode unit caused by the impurities can be particularly critical, wherein in particular the membrane and / or the catalysts of the membrane electrode unit can be damaged if they are exposed to these or are in contact with them at least temporarily, in particular over a longer period of time. Impurities may be traces and / or compounds of sulfur, formic acid, formaldehyde, ammonia, halogens, argon, methane, carbon monoxide, nonmethane hydrocarbons, and / or helium. Furthermore, these impurities can lead to the above-mentioned disadvantages.A purpose of the at least one impurity scavenger can thus be to keep impurities away from the electrolysis cell, in particular from the active region, preferably from the membrane electrode unit, or to reduce the influence of impurities on it.Contaminants can be bound at least temporarily by the contaminant scavenger. This can be achieved in particular by absorbing and / or adsorbing the impurities in and / or on the impurity scavenger. In other words, the at least one impurity scavenger substantially filters the water. In this case, in particular when the (fed) water flows through the impurity catcher, the proportion of the impurities in the water can be reduced, preferably in such a way that substantially only a few or no impurities are still present in the water when the water has flowed through the impurity catcher. Thus, the impurity scavenger can function substantially as a screen. A temporary bond may be understood to mean a permanent bond, in particular at least until a process according to the invention for cleaning is carried out. A temporary bond can mean, for example, a period of between 1 and 10000 hours, preferably between 10 and 1000, particularly preferably between 100 and 500 hours.In this case, it may be provided to use exactly one impurity scavenger. This results in simple manufacture, construction and / or low costs. Alternatively, it can also be provided to arrange two, three, four, five, six or a larger number of impurity scavengers at the same location in the electrolysis cell, for example directly one behind the other, or at different locations within the electrolysis cell. In the case of a larger number of impurity scavengers, remaining impurities can advantageously be bound at least temporarily in at least one of the downstream impurity scavengers. In other words, the purity of the water can be further increased by further impurity scavengers, which enhances the advantages according to the invention.The impurity scavenger can be arranged essentially inside the electrolysis cell, which can mean, in particular, a difference from a separate cleaning device, for example arranged upstream or outside the electrolysis cell, in particular upstream of the inlet side in the direction of flow.In this case, provision can be made for the at least one impurity scavenger to be used instead of or in addition to a cleaning device for fed water arranged outside or in front of the electrolysis cell. In the case of an additional use, the purity (or freedom from impurities) of the water can be further increased. In this case, in particular the disadvantages mentioned above with respect to the prior art can be better reduced or prevented the higher the purity of the water fed in. When used instead of a separate cleaning device, the latter can thus be dispensed with, as a result of which advantageously reduced costs and / or saved space can be achieved by means of a more compact design. In addition, a simpler, cheaper and / or more efficient electrolysis cell can be provided, in particular because removal of the impurities within the electrolysis cell can be effected more efficiently and / or more reliably than by a separate cleaning device, for example because the introduction of further impurities between the cleaning device and the electrolysis cell is ruled out. In addition, weight can be saved. Furthermore, the density of the electrolysis cell can be increased, which can lead to further degrees of freedom in the construction of an electrolysis cell, an electrolysis cell system and / or a vehicle according to the invention. For example, a heavier and / or denser electrolysis cell system in a vehicle may cause a lower center of gravity and thus advantageous driving properties. #1In the context of the invention, it may be advantageous in an electrolysis cell for the output side to have a water outlet and a hydrogen outlet. In other words, water which has not been used for electrolysis can be led out through a separate water outlet, while hydrogen also uses its own hydrogen outlet (output port). This enables separate storage and / or recycling of the water directly connected to the electrolysis cell, wherein this water can be fed back into the electrolysis cell as fed water. This makes it possible to utilize the advantage that the water which is fed in again has already been purified by the at least one impurity scavenger and therefore has fewer or no more impurities.In addition, the necessary total volume of water, which can be transported in a vehicle, for example, can be reduced. It is furthermore conceivable for oxygen likewise to be discharged through the water outlet. Thus, the number of output ports arranged on the output side can be reduced, which enables simple, inexpensive manufacture and / or lower weight. Furthermore, this can lead to oxygen binding at least some of the impurities in the water fed in or reacting with them and thus being able to be bound more easily by the at least one impurity scavenger or the impurities not being able to otherwise adversely affect the electrolysis cell. Alternatively, it is conceivable that oxygen is likewise conducted through a separate outlet, as a result of which said outlet can be used and / or stored separately on the one hand. On the other hand, this enables the water to be directly reused as fed water without any oxygen content.The above object is furthermore achieved by an electrolysis cell, wherein the at least one impurity scavenger is arranged in the first distribution region. In other words, the at least one impurity catcher essentially forms a screen for impurities at the height of the first distribution region, in particular perpendicular to the x direction. In this case, it can be provided that the at least one impurity scavenger extends substantially along the y and z directions, for example in the form of a plane or a cuboid. In this case, the at least one impurity scavenger can be arranged downstream of the inlet side, in particular of the water inlet, in the flow direction. This arrangement has the advantage that contaminants are at least temporarily bound directly after entry through the water inlet. Thus, the contaminants cannot interact with the remaining portion of the electrolytic cell. Particularly preferably, impurities are thus at least temporarily bound before they reach the membrane electrode unit or the active region. The effect of filtering the water can thus be embodied particularly strongly or efficiently in this arrangement. In this case, it can be provided to use exactly one impurity scavenger. This results in simple manufacture and construction. However, it is also possible to provide two, three, four, five, six or a larger number of impurity scavengers in the first distribution region, in particular at the same location, for example directly one behind the other, or at different locations (spaced apart) in the first distribution region. In the case of a larger number of impurity scavengers, remaining impurities can advantageously be bound at least temporarily. In other words, the purity of the water can be further increased by further impurity scavengers, which enhances the advantages according to the invention. This can be particularly advantageous since impurities already filtered out in the first distribution region, the constituents of the electrolysis cell located downstream in the flow direction (in electrolysis operation) are therefore not reached at all by the impurities. It may be particularly preferred to arrange exactly two impurity scavengers in the first distribution region. This results in a particularly advantageous compromise between comprehensive binding of contaminants and an even comparatively simple and / or cost-effective construction. Furthermore, contaminants can also be filtered out if one of the contaminant scavengers is not functional or is only partially functional, for example because already very many contaminants are at least temporarily bound to it (virtually supersaturation).The above object is furthermore achieved by an electrolysis cell, wherein the at least one impurity scavenger is arranged in the active region. In other words, the at least one impurity scavenger essentially forms a sieve for impurities at the height of the active region, in particular perpendicular to the x direction. This arrangement may be advantageous since a temperature gradient may occur along the flow direction in electrolysis operation, along the flow direction (in particular substantially along the x-direction), in particular in such a way that the temperature increases along the flow direction (e.g. due to the electrolysis). Impurities which can be bound better at higher temperatures (compared to the temperature of the water when fed in) are thus advantageously bound better by the at least one impurity scavenger. In this case, it can be provided that the at least one impurity scavenger extends substantially along the y and z directions, for example in the form of a plane or a cuboid.In this case, the at least one impurity scavenger can be arranged downstream of the inlet side, in particular the water inlet, and of the first distribution region in the flow direction. This arrangement results in the advantage that contaminants are at least temporarily bound directly after the first distribution region. Thus, the contaminants cannot interact with the remaining portion of the electrolytic cell. Particularly preferably, impurities are thus at least temporarily bound before they pass the membrane electrode unit or the active region. In this case, it may be provided to use exactly one impurity scavenger. This results in simple manufacture and construction. However, it is also possible to provide two, three, four, five, six or a larger number of impurity scavengers in the active region, in particular at the same location, for example directly one behind the other, or at different locations (spaced apart) in the active region. In the case of a larger number of impurity scavengers, remaining impurities can advantageously be bound at least temporarily. In other words, the purity of the water can be further increased by further impurity scavengers, which enhances the advantages according to the invention. This can be particularly advantageous since impurities already filtered out in the active region or at the beginning of the active region, the constituents of the electrolysis cell located downstream in the flow direction (in electrolysis operation) are therefore not reached at all by the impurities. It may be particularly preferred to arrange exactly two impurity scavengers in the active region. This results in a particularly advantageous compromise between binding of contaminants and an even comparatively simple and / or cost-effective construction. Furthermore, impurities can also be filtered out if one of the impurity scavengers is not functional or is only partially functional, for example because very many impurities are already bound to it (virtually supersaturation). It can be provided in this case to arrange a first impurity scavenger in the first distribution region and a second impurity scavenger in the active region. Thus, they are spaced apart from each other, thereby creating re-filtering in the active area after the water has been at least partially mixed. Thereby, agglomerates of impurities which may not be sufficiently bound in the first impurity scavenger may be bound in the second impurity scavenger. Furthermore, this arrangement may be advantageous since a temperature gradient may occur along the flow direction in electrolysis operation (in particular substantially along the x direction), in particular in such a way that the temperature increases along the flow direction. Thus, impurities which can be bound better at higher temperatures can be bound to the second impurity scavenger, while impurities which can already be bound at lower temperatures are bound to the first impurity scavenger at least temporarily. Advantageously, a larger proportion of impurities can thus be filtered out.The above object is furthermore achieved by an electrolysis cell, wherein the at least one impurity scavenger is arranged in the second distribution region. In other words, the at least one impurity catcher essentially forms a screen for impurities at the height of the second distribution region, in particular perpendicular to the x direction. This arrangement may be advantageous since a temperature gradient may occur along the flow direction in electrolysis operation, in particular substantially along the x-direction, in particular in such a way that the temperature increases along the flow direction (e.g. due to the electrolysis). Impurities which can be bound better at higher temperatures (compared to the temperature of the water when fed in or at the level of the active region) are thus advantageously bound better by the at least one impurity scavenger in the second distribution region. In this case, it can be provided that the at least one impurity scavenger extends substantially along the y and z directions, for example in the form of a plane or a cuboid. In this case, the at least one impurity scavenger can be arranged downstream of the inlet side, in particular the water inlet, and of the first distribution region and of the active region in the flow direction. This arrangement results in the advantage that contaminants are at least temporarily bound directly after the active region. Thus, the contaminants cannot interact with the remaining portion of the electrolytic cell. Particularly preferably, contaminants are thus bound at least temporarily before they pass the output side (e.g. the output ports), as a result of which they advantageously do not clog. In this case, it may be provided to use exactly one impurity scavenger. This results in ease of manufacture, construction and / or lower cost. However, it is also possible to provide two, three, four, five, six or a larger number of impurity scavengers in the second distribution region, in particular at the same location, for example directly one behind the other, or at different locations (spaced apart) in the second distribution region. In the case of a larger number of impurity scavengers, remaining impurities can advantageously be bound at least temporarily. In other words, the purity of the water can be further increased by further impurity scavengers, which enhances the advantages according to the invention. This can be particularly advantageous since contaminants which have already been filtered out in the second distribution region or at the beginning of the second distribution region, the constituents of the electrolysis cell which are situated downstream in the flow direction (in electrolysis operation) are therefore not reached at all by the contaminants. Since a merging can sometimes take place substantially at the level of the second distribution region of the products, this critical region is thus effectively clogged. It may be particularly preferred to arrange exactly two impurity scavengers in the second distribution region. This results in a particularly advantageous compromise between binding of impurities and an even comparatively simple construction. Furthermore, impurities can also be filtered out if one of the impurity scavengers is not functional or is only partially functional, for example because very many impurities are already bound to it (virtually supersaturation). It can be provided in this case to arrange a first impurity scavenger in the first distribution region, a second impurity scavenger in the active region and / or a third impurity scavenger in the second distribution region. Thus, these are spaced apart from one another, whereby a renewed filtering in the active region and / or second distribution region is effected after the water has been at least partially mixed along the flow direction. This allows for the agglomerations of impurities, which may not have been sufficiently bound in the first impurity scavenger, to be bound in the second and / or third impurity scavenger. Furthermore, this arrangement may be advantageous since a temperature gradient may occur along the flow direction in electrolysis operation, in particular substantially along the x-direction, in particular in such a way that the temperature increases along the flow direction. Thus, contaminants that can be more readily bound at higher temperatures can be bound to the second and / or third contaminant catcher, while contaminants that can already be bound at lower temperatures are bound to the first and / or second contaminant catcher. This allows particularly efficient temporary binding of the impurities.The above object is furthermore achieved by an electrolysis cell, wherein the impurity scavenger has a binding agent, in particular comprising activated carbon and / or antioxidants, in order to adsorb, absorb and / or chemically bind impurities. In this case, the binding agent can be configured to adsorb, absorb and / or chemically bind contaminants as completely as possible at least temporarily, wherein advantageously a binding that is as long-term (temporal) and / or efficient as possible (based on the proportion of contaminants contained in the water fed in) is achieved. Here, adsorption can be understood to mean adhesion to the binding agent. Here, absorption can be understood to mean essentially an absorption of the impurities within the binding agent. A chemical bond can be understood here to mean a chemical reaction by which the impurities react chemically at least partially with the bonding agent, and are thereby at least temporarily bonded locally in (or on) the bonding agent and / or a chemical compound is formed which, compared to the original impurity, does not act on the electrolysis cell or acts on the electrolysis cell in a less damaging manner. The binding agent can preferably be designed to be easily cleanable. This means that a method according to the invention for cleaning an electrolysis cell can clean the bonding agent particularly quickly and / or efficiently. For example, this can be achieved by a comparatively little branched lattice structure. Furthermore, this can be realized by a grid structure with preferred direction, e.g. by the structure being designed in the shape of a funnel or a cone in the direction of flow, which promotes binding of impurities, but at the same time facilitates cleaning by the method according to the invention. Alternatively or additionally, it may be advantageous if good binding of the impurities can take place in regular electrolysis operation, which can be achieved by a particularly advantageous structure and / or surface structure of the binding agent. For example, it is conceivable that the surface of the bonding agent has a roughness and / or increased surface adapted to the impurities, whereby impurities can be adsorbed, absorbed and / or chemically bonded particularly efficiently. Furthermore, it can be provided that the binding agent does not (unnecessarily) obstruct the medium flow or the flow of water, in particular in order not to slow down and / or stop a flow in the direction of flow in electrolysis operation. It can be provided that the bonding agent has the same structure as the porous transport layer and / or gas diffusion layer. Costs can thereby be saved during production. Furthermore, the flow behavior can thereby be controlled particularly efficiently. The binding agent can at least partially comprise activated carbon. As a result, on the one hand, filtering of mechanical particles, in particular dust and / or heavy metals, can take place. Furthermore, adsorption, for example of oils, can take place on the comparatively large surface. During the adsorption, impurities can be absorbed by the activated carbon and / or enriched in the activated carbon. The carbon can additionally serve as a reducing agent and / or oxidizing agent, in particular for substances such as ozone and / or chlorine. Organic substances such as halogenated hydrocarbons and / or pesticides can also be bound at least temporarily. Furthermore, the binding agent can at least partially comprise antioxidants. Antioxidants can be understood to mean a chemical compound which slows down or completely prevents oxidation of other substances. These can allow particularly efficient temporary binding of free radicals. It is also conceivable for the antioxidants to be at least partially released in order to prevent free radicals from oxidizing the electrolysis cell even at other points, i.e. not only at or in the impurity scavenger. It can be provided that a binding agent in the form of an activated carbon filter is at least partially coated by antioxidants. This results in a particularly space-saving binding means. In particular, it is conceivable that an activated carbon filter is coated on essentially one side by antioxidants, whereby the water advantageously first reaches the side coated by antioxidants when the water fed in is flown through in the electrolysis operation. This advantageously allows first at least temporary binding of impurities, which can be bound particularly efficiently by antioxidants, while subsequently at least temporary binding takes place by activated carbon. This can result in an overall particularly efficient filter effect and / or the time until the performance of a method according to the invention for cleaning is necessary (for example because of a power drop). Alternatively, it is conceivable that, when the water fed in is flowed through in electrolysis operation, the water first reaches the side not coated by antioxidants. This advantageously allows first at least temporary binding of impurities, which can be bound particularly efficiently by the activated carbon, while subsequently at least temporary binding takes place by antioxidants. This can result in an overall particularly efficient filter effect and / or the time until the performance of a method according to the invention for cleaning is necessary (for example because of a power drop). Since water can change greatly locally (e.g. depending on the continent), it is thus conceivable to use the contamination filter according to the expected water quality. It may also be provided to use a first impurity scavenger comprising activated carbon and a second impurity scavenger comprising antioxidants. This results in a simplified and / or more favorable production. Furthermore, an overall particularly efficient filtering effect can also result and / or the time until the performance of a method according to the invention for cleaning becomes necessary (for example because of power loss) can be extended, in particular if the proportion of impurities in the water (which can vary locally) changes and / or is unknown. It can also be provided to adapt the proportion (based on weight or volume) of activated carbon and / or antioxidants depending on the contaminants to be expected in the water.The above object is furthermore achieved by an electrolysis cell, wherein the membrane is a proton exchange membrane (PEM) or an anion exchange membrane (AEM). A proton exchange membrane may be considered here as a semi-permeable membrane, which is in particular made of ionomers and is preferably designed to conduct protons and at the same time to function as an electronic insulator and / or barrier for reactants, e.g. oxygen and hydrogen. As a result, the proton exchange membrane, in particular in the membrane electrode unit (MEA) of the electrolysis cell, can advantageously serve for the separation of reactants and / or for the transport of protons, while a direct electronic path is blocked by the membrane or membrane electrode unit. An anion exchange membrane may be considered a semi-permeable membrane, in particular made of ionomers, and preferably designed to conduct anions and at the same time to act as an electronic insulator and / or barrier for reactants, e.g. oxygen and hydrogen. As a result, the anion exchange membrane, in particular in the membrane electrode unit (MEA) of the electrolysis cell, can advantageously serve for the separation of reactants and / or for the transport of anions, while a direct electronic path is blocked by the membrane or membrane electrode unit.The above object is furthermore achieved by an electrolysis cell, characterized in that, in the active region, a porous transport layer (PTL) or gas diffusion layer (GDL) is arranged at least partially, in particular in each case between the membrane electrode unit and the two bipolar plates, in particular along the z-direction. In other words, an electrolysis cell preferably comprises along the z-direction a (first) bipolar plate, a (first) porous transport layer or a gas diffusion layer, a membrane electrode unit, a (second) porous transport layer or a gas diffusion layer, and a (second) bipolar plate. The bipolar plates are provided in this case in order to distribute the media (for example from the input side in the direction of the membrane electrode unit), to conduct electrons and / or to ensure the mechanical stability of the electrolysis cell. A bipolar plate usually functionally belongs to two adjacent electrolysis cells. The purpose of the porous transport layer or of the gas diffusion layer is in particular to conduct or distribute the educts and / or products during electrolysis operation, wherein the educts are transported substantially towards the membrane electrode unit and the products are transported substantially away from the membrane electrode unit. Furthermore, it can produce an electrical contact between membrane electrode unit and bipolar plates. In this case, the actual (chemical) electrolysis process can essentially take place in the active region. In this case, it can be provided that the porous transport layer or the gas diffusion layer at least partially, preferably completely, fills the space respectively formed between the membrane electrode unit and the two bipolar plates. With complete filling, particularly simple production and / or high efficiency can be achieved. In the case of partial filling, costs can be saved and / or the flow characteristic, for example of the water, can be influenced depending on the application.The above object is furthermore achieved by an electrolysis cell, characterized in that, in the first distribution region, at least one impurity scavenger (in particular in the z direction) is arranged between the membrane electrode unit and one of the two bipolar plates, in particular in an anode space, or in each case between the membrane electrode unit and both bipolar plates, in particular in an anode space and a cathode space. The anode space can be the region adjacent to the anode, while the cathode space represents the region adjacent to the cathode. The at least one impurity scavenger can be arranged substantially at the height of the first distribution region, in particular substantially perpendicular to the x-direction or in the y-z plane, which is geometrically spanned by the y-direction and the z-direction. It can be provided here that the porous transport layer or gas diffusion layer is not provided in the first and / or second distribution region, in particular at the height thereof along the x-direction. In other words, only the membrane electrode unit and the bipolar plates can be present here. This allows material and costs to be saved in this area. In this region, it can be provided that the transmission of the bracing forces, in particular of the cell stack of an electrolysis cell system, takes place via seals, in particular exclusively via seals. In this case, seals can be arranged in each case between the bipolar plates and the porous transport layer or gas diffusion layer, advantageously in order to seal different media from one another and / or from the environment. Furthermore, a sub-rocket frame can be provided between the bipolar plates (or seals) and the porous transport layer (or gas diffusion layer), which advantageously enables electrical insulation of the reaction sides and / or brings about mechanical stabilization. The membrane electrode unit preferably has no catalyst or no catalyst coating in the first and / or second distribution region, advantageously in order to achieve simpler and / or more cost-effective production. Thus, the electrolysis cell can have only the membrane electrode unit, the bipolar plates and / or the sub-diketene frame in the first and / or second distribution region. This can save costs and simplify the construction. It can be provided that in this region the at least one impurity scavenger is arranged on the membrane electrode unit, on at least one of the sides of the bipolar plates and / or the sub-rocket frame. Depending on the type and intended use, the at least one impurity scavenger can be applied as a constituent of the membrane electrode unit, in particular of the membrane, preferably of the ionomer of the membrane, and / or as a coating to membrane, sub-rocket frame and / or bipolar plate. A coating can thereby achieve a particularly stable and surface-covering application. The arrangement as a component of the membrane electrode unit, in particular of the membrane, preferably of the ionomer of the membrane, allows integrated production and additionally allows use in existing electrolysis cells, since only this membrane electrode unit which is necessary in any case can be replaced or exchanged. An arrangement on both sides of a bipolar plate may be advantageous since an arrangement can thus be effected on both sides of a bipolar plate, for adjacent electrolysis cells of an electrolysis cell system in the form of a stack, which may allow symmetrical and simplified production. An arrangement on the sub-rocket frame may allow a mechanically particularly robust arrangement and ensures that the contaminant catcher does not shift unintentionally during operation.The above object is furthermore achieved according to a second aspect of the invention by an electrolysis cell system according to the invention, wherein the electrolysis cell system comprises at least two electrolysis cells, in particular according to one of Claims 1 to 9, wherein the electrolysis cells are arranged directly adjacent in a stack. In other words, a cell stack is formed from electrolysis cells, wherein in particular bipolar plates and membrane electrode units are alternately stacked one above the other.Advantages which have been described in detail with respect to an electrolysis cell according to the first aspect of the invention apply equally to the electrolysis cell system according to the second aspect of the invention.The above object is furthermore achieved according to a third aspect of the invention by a vehicle according to the invention, wherein in particular at least one electrolysis cell system according to the second aspect of the invention is comprised, wherein the electrolysis cell system is configured to provide hydrogen, air, oxygen and / or water, in particular purified wastewater. In this case, in particular the wastewater, which preferably corresponds to fed water filtered by the at least one impurity scavenger, can have a comparatively high purity. Thus, the water can be reused, for the electrolysis cell or the electrolysis cell system (refeeding) and / or other devices. A vehicle can therefore carry less water altogether for such applications, which leads to a saving in weight. Hydrogen and / or oxygen can be used for the operation of a fuel cell. Furthermore, these, as well as air, can be used as cooling medium or heating medium, depending on the temperature.The above object is furthermore achieved according to a fourth aspect of the invention by a method according to the invention for cleaning an electrolysis cell, in particular according to the first aspect of the invention, wherein in at least one cleaning step for cleaning the impurity scavenger the electrolysis cell is flushed with a flushing medium counter to the flow direction provided in electrolysis operation, whereby impurities bound at least temporarily to or in the impurity scavenger are flushed out via the inlet side, in particular via the water inlet. This achieves removal of the contaminants bound to and / or in the contaminant scavenger, in particular adsorbed, chemically bound and / or absorbed contaminants. The cleaning step can be considered a rinsing or recovery step. The flushing medium can be transported through the electrolysis cell counter to the direction of flow provided in electrolysis operation, as a result of which no additional connections are necessary, since the connections present on the inlet and outlet sides, in particular water inlet and water outlet, can be used. This saves weight and / or costs. Furthermore, this may result in the advantage that impurities are flushed out of the electrolysis cell without these having to be guided over the active region, in particular if the at least one impurity scavenger is positioned in the first distribution region. As a result, the active region, in particular the membrane electrode unit, the second distribution region and / or the output side can be protected particularly efficiently from contaminants. It can be provided that during the cleaning step only the anode space is rinsed, in particular when the at least one impurity scavenger is only at least partially arranged there. As a result, the time required for carrying out the method and / or the necessary volume of the flushing medium can be minimized. In addition, a higher temperature can be achieved during the temperature control, since less volume of the flushing medium has to be heated. Furthermore, the cleaning step can preferably be carried out repeatedly, in particular whenever a threshold value is exceeded or undershot. In this case, for example, a method, in particular the cleaning step, can be initiated, for example by a control unit, when the power of the electrolysis cell or of the electrolysis cell system falls below a specific threshold value, which can be monitored, for example, by a sensor. Alternatively or additionally, a temperature exceeded in electrolysis operation can be used as threshold value in order to prevent the electrolysis cell or the electrolysis cell system from running hot by carrying out a cleaning in good time. It can thus be ensured that the power is substantially constant or does not leave a specific window (upper and lower limit). This can increase durability, efficiency, and / or safety, in particular. Furthermore, blockages of the individual constituents mentioned above of the electrolysis cell or of the electrolysis cell system can thus be prevented and / or a uniform flow can be achieved. The efficiency can also be kept constant or within a certain window, i.e. it is subject to minor fluctuations. In this case, the cleaning step is preferably repeated regularly, for example after a cleaning-free period of time of between 1 and 10000 hours, preferably between 10 and 1000, particularly preferably between 100 and 500 hours. Alternatively or additionally, it can be provided that after each, preferably after every tenth, particularly preferably after every one hundredth, interruption of the electrolysis operation, a method according to the invention for cleaning is carried out. This results essentially always in the same initial state. It is also conceivable that the method for cleaning is scheduled in advance in order to be able to efficiently use downtime. An example would be the end of a multi-step trip in a vehicle in accordance with the invention.In the context of the invention, it is conceivable that in the at least one cleaning step, the electrolysis cell is rinsed with water fed in. Alternatively or additionally, it can be provided that air and / or hydrogen are used as the flushing medium. This results in the advantage that no additional separate flushing medium has to be used, whereby costs and / or weight can be saved. In addition, cleaning is thereby possible at any time. In addition, the electrolysis cell is thus structurally simpler and / or less susceptible to errors. Furthermore, this may be advantageous since the water, the air and / or the hydrogen already fed in has been substantially purified, and thus no further contaminants can be introduced. Water may be particularly suitable for cleaning mechanically, for example to flush out particles. Hydrogen, air and / or oxygen may be particularly suitable for reacting and / or binding oxides. In this case, it can be provided to carry out a (first) cleaning step with water and a further (second) cleaning step with water, hydrogen, air and / or oxygen in order to achieve particularly efficient cleaning in each case. Alternatively or additionally, it is conceivable to use and / or mix in a separate flushing medium. This can enhance the cleaning effect. For example, it may be necessary to mix an alternative and / or more aggressive cleaning agent after a number of 1 to 10000, preferably 10 to 1000, particularly preferably 100 to 500 cycles of the method according to the invention, in order to remove contaminants which are difficult to dissolve and thus to further increase the service life, performance and / or efficiency. Here, gases freed from contaminants, in particular noble gases or oxygen, are conceivable as a separate flushing medium. Alternatively or additionally, distilled water would be conceivable. Furthermore, the use of acids, for example acetic acid, formic acid, methanesulfonic acid, hydrofluoric acid and / or alkalis is conceivable. These separate rinsing media can be carried in compressed form in an external reservoir in order to enable cleaning at any time. Alternatively, these can be used within the scope of regular maintenance, whereby weight and complexity can be saved. In this case, it can be provided to temperature control the separate flushing medium, as a result of which this has a temperature between 1 and 500° C., preferably between 10 and 250° C., particularly preferably between 30 and 200° C., advantageously between 50 and 150° C., ideally between 80 and 130° C., for example between 90 and 110° C. Alternatively or additionally, it is conceivable to subject the flushing medium to an (additional) pressure which is preferably higher than the pressure used in normal electrolysis operation, as a result of which an even more complete and / or more efficient cleaning is made possible (virtually blowing free).It can be provided within the scope of the invention that after the at least one cleaning step a checking step is carried out in order to determine the successful flushing out of contaminants, in particular via a visual check, at least one sensor and / or by checking the material composition of the (fed) water and / or wastewater. Alternatively or additionally, it can be provided to carry out a checking step during, after and / or before operation, in particular in order to ensure safe and efficient operation. In this case, a visual check by the naked eye can be provided, which is possible in all places, for example in the case of at least partial transparency of the electrolysis cell. Optical monitoring by a microscope and / or transillumination, for example by a laser, is also possible. The sensor can detect the light emitted by the laser. It may be provided that the process according to the invention is carried out for the first time or again if impurities are detected in the electrolysis cell or in at least one electrolysis cell of an electrolysis cell system. Thus, a first time or repurification can be performed when necessary or only when necessary. Unnecessary cleaning steps are thus avoided. At the same time, damage up to total decay can be effectively prevented.In the context of the invention, it is conceivable that at least one first temperature-control step is carried out before the at least one cleaning step in order to achieve an at least partial temperature change of the impurity scavenger and / or of the impurities, in particular for facilitated cleaning, and / or that after the at least one cleaning step at least one second temperature-control step is carried out in order to achieve an at least partial temperature change of the impurity scavenger and / or of the impurities, in particular for facilitated cleaning. In the simplest case, it can be provided that the water fed in is tempered, as a result of which impurities are at least partially rinsed out. This can be provided along the flow direction in electrolysis operation (i.e. explicitly during electrolysis), along this direction without electrolysis being operated and / or counter to this direction without electrolysis being operated. This can result in an increase in the temperature of the impurity scavenger and / or of the impurities, which promotes a flushing out (in particular dissolution of adsorption and / or absorption) of the impurities and leads to a more complete or complete cleaning of these. In this case, the flushing medium, in particular water, which then contains the flushed-out impurities, is preferably removed, in particular via the inlet or outlet side. It is furthermore conceivable for a tempering step to be arranged upstream of the cleaning step according to the invention. For example, during electrolysis, the temperature can additionally be increased in order to dissolve first impurities and flush them out along the flow direction in electrolysis operation (similar to the cleaning of a diesel particle filter) and subsequently carry out a cleaning step in the opposite direction. Thus, a particularly comprehensive cleaning can be achieved. Additionally or alternatively, a (second) temperature control step and / or cleaning step can be carried out subsequent to the cleaning step. Thus, the efficiency of the cleaning can be further increased. It is also conceivable to adapt the number and sequence of the cleaning and / or tempering steps to the impurities currently present in the water fed in. The contaminations can be determined via a water sample and consequently the optimal sequence can be determined. Alternatively or additionally, it is conceivable that a temperature control step is used to lower the temperature of the electrolysis cell and / or of the electrolysis cell system. For example, hot running and partial or complete destruction can be prevented when an excessively high temperature is reached. In this case, a cooled flushing medium can flow through the electrolysis cell and / or the electrolysis cell system in order to reduce the temperature. The cleaning process according to the invention can then be carried out in order to remove impurities which may have caused the elevated temperature in particular.Advantages which have been described in detail with respect to an electrolysis cell according to the first aspect of the invention or with respect to an electrolysis cell system according to the second aspect of the invention apply equally to a vehicle according to the third aspect of the invention and to a method for cleaning an electrolysis cell according to the fourth aspect of the invention.Further advantages, features and details of the invention will become apparent from the following description, in which a plurality of exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description can be essential to the invention individually or in any combination. The invention is shown in the following figures: FIG. 1 shows the anode compartment of an electrolysis cell FIG. 2 shows a section through an electrolysis cell in the active region FIG. 3 shows a section through an electrolysis cell in the first or second distribution region FIG. 4 shows a section through an electrolysis cell in the first or second distribution region FIG. 5 shows a schematic sequence of the method for cleaning an electrolysis cellFIG. 1 shows an electrolysis cell 1 according to the invention, wherein the electrolysis cell 1 comprises, along an x direction (in an x-y-z righthand system): an inlet side 2 with a water inlet 21 for feeding water 20, a first distribution region 3 adjoining the inlet side 2, an active region 4 adjoining the first distribution region 3, a second distribution region 5 adjoining the active region 4, an outlet side 6 adjoining the second distribution region 5, wherein the fed water 20 or waste water can flow off via a water outlet 60 in order in particular to be fed in again at least partially via the water inlet 21. Hydrogen can leave the electrolysis cell 1 via the hydrogen outlet 61. During electrolysis operation, the water 20 fed in flows through the electrolysis cell along the flow direction 80. By way of example, a first impurity scavenger 9 is arranged in the first distribution region 3, a second impurity scavenger 9 is arranged at the beginning of the active region 4, and a third impurity scavenger 9 is arranged in the second distribution region 5.FIG. 2 shows the electrolysis cell 1 according to the invention in a section at the height of the active region. The electrolysis cell 1 has a membrane electrode unit 7 along a z-direction, which is arranged between two bipolar plates 8. Between the bipolar plates 8 and the membrane electrode unit 7, a porous transport layer 11 or gas diffusion layer 11 is arranged. Functionally, a bipolar plate 8 belongs to two adjacent electrolysis cells 1.FIG. 3 shows the electrolysis cell 1 according to the invention in section at the height of the first or second distribution region. The electrolysis cell 1 has a membrane electrode unit 7 along a z-direction, which is arranged between two bipolar plates 8. Between the bipolar plates 8 and the membrane electrode unit 7, a respective impurity scavenger 9 is partially arranged in order to at least temporarily bind impurities from the water 20 fed in.FIG. 4 shows the electrolysis cell 1 according to the invention in section at the height of the first or second distribution region. The electrolysis cell 1 has a membrane electrode unit 7 along a z-direction, which is arranged between two bipolar plates 8, wherein the membrane electrode unit 7 has two electrodes 70, comprising an anode 71 and a cathode 73, between which a membrane 72 is arranged. The electrolysis cell 1 also has an impurity scavenger 9, which is arranged in the anode space 710 adjoining the anode over the entire width along the y-direction. The cathode space 730 adjoining the cathode is not filled in this case.Electrolysis cells 1 stacked one above the other, in particular along the z-direction, according to FIGS. 2, 3, 4, can form an electrolysis cell system 10.FIG. 5 shows a schematic sequence of the method 100 for cleaning an electrolysis cell 1 or an electrolysis cell system 10. This may be preceded by a (first) temperature control step 101, for example in order to heat the flushing medium, such as the water 20 fed in. In the (first) cleaning step 103, the latter can then flow through the electrolysis cell 1 along the flow direction in the electrolysis operation 80, along the flow direction 80 without electrolysis operation or counter to the flow direction (i.e. counter to the direction 80 shown) in order to remove impurities from and / or from the impurity scavenger 9. Furthermore, a further second temperature control step 105, which can be in particular identical to the first temperature control step 101, can be carried out. A different temperature, in particular a higher temperature, can be selected than in the first temperature control step 101. This can also remove particularly stubborn and / or remaining impurities. A further (second) cleaning step 107 can then take place, which can be identical to the first cleaning step 103. It may be provided to carry out this for a longer time, in particular if the second cleaning step was carried out only because a previous cleaning was insufficient. Subsequently, a checking step 109 can be carried out in order to determine the successful flushing out of contaminants, in particular via a visual check, at least one sensor and / or by checking the material composition of the (fed) water and / or wastewater. If the removal of the impurities is at least partially unsuccessful, for example because too many impurities can be detected in the waste water, the first temperature control step 101, the cleaning step 103, the second temperature control step 105 and / or the second cleaning step 107 can be carried out again. A further checking step 109 can then be carried out until the contaminants have been removed for the most part, preferably completely.List of reference characters1 Electrolysis cell 2 input side 3 first distribution region 4 active region 5 second distribution region 6 output side 7 membrane electrode unit 8 bipolar plates 9 impurity catcher 10 electrolysis cell system 11 porous transport layer / gas diffusion layer 20 (fed) water 21 water inlet 60 water outlet 61 hydrogen outlet 70 electrodes 71 anode 72 membrane 73 cathode 80 flow direction 100 method 101 first temperature control step 103 cleaning step 105 second temperature control step 107 second cleaning step 109 checking step 710 anode space 730 cathode space x x x direction y direction z direction

Claims

Electrolysis cell (1) comprising: - an inlet side (2) with a water inlet (21) for feeding water (20) - a first distribution region (3) adjoining the inlet side (2), - an active region (4) adjoining the first distribution region (3), - a second distribution region (5) adjoining the active region (4), - an outlet side (6) adjoining the second distribution region (5), further comprising: - a membrane electrode unit (7) arranged between two bipolar plates (8), wherein the membrane electrode unit (7) has two electrodes (70) comprising an anode (71) and a cathode (73), between which a membrane (72) is arranged, characterized in that the electrolysis cell has at least one impurity scavenger (9) in order to at least temporarily bind impurities from the fed water (20).Electrolysis cell according to Claim 1, characterized in that the output side (6) has a water outlet (60) and a hydrogen outlet (61).Electrolysis cell according to one of the preceding claims, characterized in that the at least one impurity scavenger (9) is arranged in the first distribution region (3).Electrolysis cell according to one of the preceding claims, characterized in that the at least one impurity scavenger (9) is arranged in the active region (4).Electrolysis cell according to one of the preceding claims, characterized in that the at least one impurity scavenger (9) is arranged in the second distribution region (5).Electrolysis cell according to one of the preceding claims, characterized in that the impurity scavenger (9) has a binding agent, in particular activated carbon and / or antioxidants, in order to adsorb, absorb and / or chemically bind impurities.The electrolytic cell according to any one of the preceding claims, characterized in that the membrane (72) is a proton exchange membrane or an anion exchange membrane.Electrolysis cell according to one of the preceding claims, characterized in that, in the active region (4), a porous transport layer (11) or gas diffusion layer (11) is arranged at least partially, in particular in each case between the membrane electrode unit (7) and the two bipolar plates (8).Electrolysis cell according to one of the preceding claims, characterized in that, in the first distribution region (3), at least one impurity scavenger (9) is arranged between the membrane electrode unit (7) and one of the two bipolar plates (8), in particular in an anode space (710), or in each case between the membrane electrode unit (7) and both bipolar plates (8), in particular in an anode space (710) and a cathode space (730).Electrolysis cell system (10) comprising at least two electrolysis cells (1) according to one of Claims 1 to 9, wherein the electrolysis cells (1) are arranged directly adjacent in a stackVehicle comprising at least one electrolysis cell system (10) according to claim 10, wherein the electrolysis cell system (10) is configured to provide hydrogen, air, oxygen and / or water, in particular purified wastewater.Method (100) for cleaning an electrolysis cell (1) according to one of Claims 1 to 9, characterized in that, in at least one cleaning step (103) for cleaning the impurity scavenger (9), the electrolysis cell (1) is flushed with a flushing medium counter to the flow direction (80) provided in electrolysis operation, as a result of which impurities bound at least temporarily to or in the impurity scavenger are flushed out via the inlet side (2), in particular via the water inlet (21).Method (100) according to claim 12, characterised in that in the at least one cleaning step (103), the electrolysis cell (1) is rinsed with water (20) fed in.Method (100) according to claim 12 or 13, characterised in that after the at least one cleaning step (103) a checking step (109) is carried out in order to determine the successful flushing out of impurities, in particular via a visual check, at least one sensor and / or by checking the material composition of the water.Method (100) according to one of claims 12 to 14, characterised in that before the at least one cleaning step (103) at least one first temperature control step (101) is carried out in order to achieve an at least partial temperature change of the impurity scavenger (9) and / or the impurities, in particular for facilitated cleaning, and / or that after the at least one cleaning step (103) at least one second temperature control step (105) is carried out in order to achieve an at least partial temperature change of the impurity scavenger (9) and / or the impurities, in particular for facilitated cleaning.

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