Electrochemical cell structure

Abstract

To provide an electrochemical cell that is low in production cost, can be constructed in a space saving manner, can generate a large amount of hydrogen and oxygen with excellent energy efficiency, and can carry out AEM water electrolysis on an industrial scale.SOLUTION: An electrochemical cell (0) for alkali membrane water electrolysis, comprises an anode (1), a cathode (2) and an anion conductive membrane (3) disposed between the anode (1) and the cathode (2), with the anode (1) being partially or entirely structured as a first porous sintered body (1) including particles fused with each other at grain boundaries, and the first porous sintered body (1) being in direct contact with the membrane (3). There is provided the use of the electrochemical cell (0) in a method of generating hydrogen and oxygen by electrochemically decomposing water. There are further provided an electrolysis tank comprising the plurality of cells (0), and a method of producing the electrolysis tank.SELECTED DRAWING: Figure 1a

Description

[Technical field]

[0001] The present invention relates to an electrochemical cell having an anode, a cathode, and an anion-conducting membrane disposed between the anode and the cathode. The present invention also relates to the use of the electrochemical cell in a process for producing hydrogen and oxygen by electrochemical decomposition of water. The present invention further relates to an electrolytic cell having a multiplicity of cells, and a method for producing the electrolytic cell. [Background technology]

[0002] Electrochemical cells are used to carry out electrochemical processes. There are many electrochemical processes with different purposes. An important electrochemical process is the decomposition of chemical compounds. This process is called electrolysis.

[0003] The industrial realization of an electrochemical cell for carrying out electrolysis is called an electrolyser, which usually consists of a number of interconnected electrochemical cells.

[0004] An electrochemical cell has at least two electrodes, an anode and a cathode. The cell is usually divided into two compartments by an electrically insulating separator. The anode is in the first, "anodic" compartment, and the cathode is in the second, "cathodic" compartment. The two electrodes or compartments are electrically isolated from each other by the separator. The electrochemical cell is filled with an electrolyte.

[0005] The key electrochemical process is the production of hydrogen and oxygen by the electrochemical decomposition of water. One variant of water electrolysis is characterized by the use of an anion conducting membrane (anion exchange membrane, AEM) as a separator. This is commonly called AEM water electrolysis (AEMWE). As the reaction takes place in an alkaline medium, AEM water electrolysis is also called alkaline membrane water electrolysis.

[0006] In AEM water electrolysis, an electrochemical cell is filled with water or a basic water-based electrolyte and a voltage is applied between the anode and cathode. 2O) is hydrogen (H 2 ) and hydroxide ion (OH - ) (Equation C). The anion exchange membrane transports the hydroxide ions to the anode side, where they are converted to oxygen (O 2 ) (Equation A). As a result, oxygen is produced on the anode side and hydrogen is produced on the cathode side. Therefore, the anode side is also called the oxygen side and the cathode side is also called the hydrogen side. 2H 2 O+2e - →H 2 +2OH - (C) Reduction / cathode reaction 2OH - →1 / 2O 2 +H 2 O+2e - (A) Oxidation / anodic reaction

[0007] To achieve the described effect, the membrane must conduct hydroxide ions between the anode and cathode. At the same time, the membrane must be electrically insulating to prevent an electrical short circuit between the anode and cathode. Finally, the anion-conducting membrane must be as gas-tight as possible to prevent backmixing of the evolved gases. Furthermore, the anion-conducting membrane must withstand the alkaline conditions present in AEM water electrolysis. These properties are achieved by special anion-conducting polymers (also called anion-conducting ionomers).

[0008] To accelerate the reaction, catalytically active substances (also called electrocatalysts) are incorporated on both the cathode and anode sides. This is achieved by introducing catalytically active layers. These may be present on substrate materials specially introduced into the cell for this purpose, on porous transport layers (catalyst coated substrates, CCS), or the membrane may be directly coated with catalytically active materials (catalyst coated membranes, CCM).

[0009] In AEM water electrolysis, it is necessary to realize the flow of water or electrolyte through the cell and the flow of gas from the cell to supply fresh water for electrolysis and then to discharge hydrogen and oxygen or water or electrolyte enriched with them. This is usually made possible by a porous transport layer (PTL) that is closely adjacent to the catalytically active layer to allow good electrical contact. The porous transport layer is then electrically conductive and has sufficient porosity for the outward transport of gas and the supply of water and electrolyte. To improve the transport of water or electrolyte through the cell, a specific channel structure (called a flow field) is incorporated into the cell. This structure is in electrical contact with the porous transport layer, is electrically conductive, and establishes electrical contact with a bipolar plate (BPP). The bipolar plate electrically connects two adjacent cells. The specific channel structure is often directly incorporated into the bipolar plate, for example by mechanical deformation. For efficient water electrolysis, it is particularly important to keep the contact resistance at the interface between (i) the catalytically active layer and the porous transport layer, (ii) the porous transport layer and the flow field, and (iii) the flow field and the bipolar plate as low as possible and to prevent the contact resistance from increasing due to oxidation of the interface during operation of the electrolyzer, otherwise the contact resistance will increase, leading to an increase in the cell voltage, a decrease in efficiency, and an increase in energy consumption.

[0010] A good overview of the electrochemical cell structures and materials currently used in AEM water electrolysis is given in the following publications: Miller, Hamish Andrew et al.: Green hydrogen from anion exchange membrane water electrolysis: A review of recent developments on key materials and operating conditions, Sustainable Energy Fuels, 2020, 4, 2114DOI:10.1039 / c9se01240k

[0011] The general objective in the development of electrolyzers for water electrolysis is to improve the efficiency of the process and reduce the manufacturing costs of the electrolyzers.

[0012] In the review cited by Miller et al., nickel foam is mentioned as an electrode material. Foams are porous structures.

[0013] EP 3 453 785 A describes an electrochemical cell for basic water electrolysis. In paragraph

[0022] an anode is disclosed having a feeder layer (17) made partly of a metal nonwoven fabric or metal foam. The material specified in paragraph

[0023] is nickel or stainless steel. Between the nonwoven fabric and the membrane (13) another catalyst layer (15) is arranged (see FIG. 1 and paragraphs

[0015] and

[0027] ). The electrode-catalyst layer-membrane-catalyst layer-electrode sandwich structure (see paragraph

[0053] ) of the electrochemical cell is very space consuming. This is particularly disadvantageous when a large number of such cells are connected to an electrolyzer. In this case, not only the space occupied by the electrolyzer increases, but also the internal resistance of the cell stack. This reduces the energy efficiency of the process. An excellent feature of the electrochemical cell shown in EP 3 453 785 A is the fluid management. The membrane is provided with channels to improve the inflow of water into the compartment and the outflow of gas from the compartment (paragraph

[0054] ). The electrochemical cell would therefore in principle be suitable for industrial water electrolysis. Disadvantages are the space-consuming layer structure and the high manufacturing costs resulting from the incorporation of a catalytic layer, which contains valuable metals that act as electrocatalysts (see paragraph

[0029] ).

[0014] WO 2020 / 260370 describes an electrochemical cell in which one compartment can be operated dry. On page 5, CCS on nickel nonwoven fabric or foam is mentioned. However, the CCS always has a catalyst layer. On page 6 above, metal oxides are recommended as electrocatalysts for the anode, for example copper-cobalt oxide. However, on page 6 of WO 2020 / 260370, Pt catalysts are not recommended for cost reasons.

[0015] WO 2016 / 142382 discloses in FIG. 2 an embodiment I of a (photo)electrochemical cell having a cathode (anti-corrosion layer 15 of the photoelectrode 2), an anion-conducting membrane (2) and an anode (counterelectrode 3). Between the anode (3) and the membrane (2) a porous nickel-containing structure (5A) is arranged. The porous nickel-containing structure (5A) can consist of nickel fibres or stainless steel fibres. Nickel foam is also conceivable (page 12). As shown in FIG. 2 and described on page 17, the anode (counterelectrode 3) is spaced apart from the membrane. The porous nickel-containing structure (5A) is arranged between them. A disadvantage of this cell is its voluminous layer structure.

[0016] A slimmer solution is embodiment II of WO 2016 / 142382, which does not require a porous nickel-containing structure. The porosity required for fluid conduction is realized in the membrane. Since the photoelectrochemical cell has an integrated voltage source (i.e., a photoelectrode), the available electrical energy for water electrolysis is limited. When purely light-driven, the electrolysis capacity is low. In industrial water electrolysis with external electrical energy, large amounts of gaseous hydrogen and oxygen are generated, which need to be led out of the cell. The membrane-integrated porous structure of embodiment II is not designed for this amount of gas. Nevertheless, the structure of embodiment II is too large for the design of compact electrolyzers on an industrial scale.

[0017] EP 4181240, unpublished at the time of filing the present application, also relates to an electrochemical cell for water electrolysis comprising a woven electrode containing nickel, the woven electrode being directly adjacent to a membrane. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] European Patent Application Publication No. 3453785 [Patent Document 2] International Publication No. 2020 / 260370 Brochure [Patent Document 3] International Publication No. 2016 / 142382 Brochure [Patent Document 4] European Patent Application Publication No. 4181240 Summary of the Invention [Problem to be solved by the invention]

[0019] With respect to this prior art, the objective of the present invention is to identify an electrochemical cell capable of performing AEM water electrolysis on an industrial scale, which should be inexpensive to manufacture, require a small space to construct, and produce large amounts of hydrogen and oxygen in an energy-efficient manner. [Means for solving the problem]

[0020] This object is achieved by an electrochemical cell according to claim 1.

[0021] The present invention therefore provides an electrochemical cell for alkaline membrane water electrolysis comprising an anode, a cathode and an anion-conducting membrane arranged between the anode and the cathode, the anode being partially or completely constructed as a first porous sintered body comprising grains fused together at grain boundaries, the first porous sintered body being in direct contact with the membrane.

[0022] An important finding of the present invention is that the porous structure in the form of a sintered body is not only suitable as an electrode, but can simultaneously assume the function of a porous transport layer for the electrolyte and / or the evolved gas. The sintered body is essentially porous, since there are cavities between the individual particles. This is because the particles are irregularly shaped and sometimes only partially fused. Water or electrolyte can penetrate into these cavities and thereby come into contact with the electrode material. This allows the reactants to reach the catalytically active centers directly through the porous cavities in the sintered body. The evolved gases can likewise escape from the cavities. The sintered body therefore performs not only an electrochemical function, but also a fluid function.

[0023] The fluid conducting properties of the porous electrode allow it to be in direct contact with the membrane. This means that the sintered body is in direct planar contact with the membrane. Therefore, no catalytic layer is arranged between the anode and the membrane. The membrane and the sintered body are therefore in direct mechanical contact, preferably over the entire membrane-electrode interface. However, since the membrane is not electrically conductive, there can be no contact problems in the electrical sense. The fluid conducting properties of the sintered body allow the electrochemical cell of the invention to operate without an additional porous transport layer. This reduces the electrical internal resistance of the cell, since there is no contact resistance between the individual components that are usually used. Nevertheless, it may be necessary to incorporate flow fields into the electrochemical cell that direct the electrolyte and gas into and out of the cell. However, the flow fields are located away from the membrane, preferably the flow fields are incorporated into the bipolar plates or end plates. The flow fields have a much larger cross-sectional area for flow compared to the pores of the sintered body.

[0024] Sintered bodies differ from known woven structures in that they are not composed of linear woven structures such as fibers, threads, yarns, or wires. Sintered bodies are instead formed from particles.

[0025] Sintered bodies differ from known metal foams in that they are formed at least in part from grains joined at grain boundaries. Thus, sintered bodies are not monolithic. Metal foams, on the other hand, have a monolithic metal dispersed phase in which a gas phase is dispersed. The pores of sintered bodies are usually much smaller than the individual grains. In contrast, metal foams have pores that are relatively large compared to their metal phase.

[0026] In a particularly preferred embodiment, the particles of the sintered body exclusively or at least comprise catalytically active material. In the context of this specification, "catalytically active" means that the material is capable of accelerating an electrochemical reaction taking place in an electrochemical cell. Thus, the catalytically active material is an electrocatalyst.

[0027] The use of catalytically active sintered materials allows the reactants to be in particularly intimate contact with the catalytically active centers present within the particles of the sintered material, so that the electrochemical reactions can take place very close to the membrane, allowing the ions produced to pass directly through the membrane into the opposite compartment.

[0028] Electrocatalytically active materials usually contain transition metals. Transition elements, for the purposes of the present invention, are Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Ac, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg. Sintered materials containing transition elements have a higher electrocatalytic activity than sintered materials that do not contain transition elements. Furthermore, the relatively good electrical conductivity of transition metals reduces the internal electrical resistance of the electrochemical cell.

[0029] Particularly preferably, nickel is used as the electrocatalytically active material. Thus, in a preferred embodiment of the invention, the particles of the sintered body comprise nickel or only nickel. The particles themselves are electrocatalytically active.

[0030] Nickel is a relatively inexpensive transition metal with good catalytic properties, especially in water electrolysis. In addition, there are several nickel-containing materials that can be easily sintered into anodes. These materials include pure nickel, nickel-containing alloys, especially Hastelloy, Cronin, Monel, Inconel, Incoloy, Invar, Kovar, nickel-containing steels, nickel-containing stainless steels, as well as steels of the AISI301, AISI301L, AISI304, AISI304L, AISI310, AISI310L, AISI316, AISI316L, AISI317, AISI317L and AISI321 types.

[0031] Thus, in a particularly preferred embodiment of the invention, the anode is at least partially configured as a first sintered body, the particles of which comprise a nickel-containing material.

[0032] A further advantage of the electrochemical cell of the invention is that no ionomer (often also called binder) is absolutely necessary to fix the electrocatalyst on the substrate or electrode (CCS) or directly on the membrane (CCM). The oxygen produced during electrolysis is very active and can chemically attack (oxidize) the ionomer, which can impair its mechanical properties and also cause the electrocatalyst to spall. This results in an increase in the required cell voltage and in the energy consumption. However, if the sintered body itself is electrocatalytically active, the risk of catalyst spalling is less. As a result, the proposed electrochemical cell structure reduces the manufacturing costs and allows for a more energy-efficient process due to its low electrical resistance.

[0033] Considering the advantages of the sintered structure, the anode is preferably entirely constructed in the form of a porous sintered body. However, it is also conceivable to use an anode that is only partially constructed in the form of a porous sintered body and otherwise made of non-sintered material. Non-sintered means that there are no discernible grain boundaries. Thus, the sintered body can be mounted on a solid plate, or on a flat or formed metal sheet, or even on different porous structures such as metal foams, expanded metals or expanded metal meshes.

[0034] Preferably, the first sintered body does not comprise a catalytically active coating distinct from the material of the sintered body, in which case the catalysis of the anodic reaction is exclusively carried out by the electrocatalytically active material present in the sintered body or constituting the particles of the sintered body.

[0035] The porosity P of the first porous sintered body used as the anode must be in the range of 5% to 60% or 15% to 45%. The porosity P is measured according to the following formula: P=1-ρ V / ρ M (In the formula, ρ V is the volume density of the porous sintered body, and ρ M is the solid density of the particle. ρ V represents the macro density of the entire sintered body, and ρ Mrepresents the microdensity of the sintered material that makes up the particle.)

[0036] Compared to foams, the porosity of sintered bodies is significantly lower, and the porosity of nickel foams typically varies between 80% and 90%; Rocha Fernando et al.: Effect of pore size and electrolyte flow rate on the bubble removal efficiency of 3D pure Ni foam electrodes during alkaline water electrolysis. See Table 1 in Journal of Environmental Chemical Engineering, Volume 10, Issue 3, April 1, 2022 (2022-04-01), Page 107648, ISSN: 2213-3437, DOI: 10.1016 / 3.jece.2022.107648.

[0037] In the simplest case, the porosity in the first sintered body is the same everywhere. Preferably, the porosity in the first sintered body can vary along a (virtual) gradient, specifically arranged perpendicular to the interface between the first porous sintered body and the membrane. The porosity P should decrease in the direction of the membrane, so that the porosity of the first sintered body is lower at the interface with the membrane than on the anode side away from the membrane. This means that the catalytically active centers are concentrated in the membrane, so that the electrochemical reaction is particularly strong there. This shortens the path of the ions generated at the anode.

[0038] Preferably, the pores of the first porous sintered body are smaller than the grains of the first porous sintered body. This is a major difference from foams, where the pores are larger than the solid material. The size difference can be easily determined by examining an optical microscope, i.e., a cross-section of the first porous sintered body. The pore sizes of the sintered body show a random distribution. The pore sizes are usually 1 μm to 200 μm. The pore sizes of the sintered body are also much smaller than the typical flow cross-sectional area of ​​the flow field, which is in the range of 1 mm.

[0039] The grain size of sintered bodies also shows a random distribution. To evaluate the difference between pore size and grain size, compare the median values, not the extreme values. It does not matter if the individual extremely large pores are larger than the extremely small grains, as long as the median pore size is smaller than the median grain size. The property of sintered bodies in which the pore size is smaller than the grain size means that statistically, the median pore size is smaller than the median grain size.

[0040] The first porous sintered body may be formed from at least two layers, the two layers having different porosity or composed of particles of different grain size. The layer with less porosity or composed of finer grains should be placed closer to the membrane than the layer with more porosity or composed of coarser grains. This causes the porosity of the electrode to decrease towards the membrane. In other words, the electrode is denser and composed of finer grains. This is recommended because closer to the membrane there should be a higher density of catalytically active sites, while away from the membrane there should be a higher permeability to water or electrolyte and product gases. The sintered body may also be formed from more than two layers, for example three, four, five or six layers. The porosity or grain size of the sintered grains of the individual layers decreases stepwise from layer to layer in the direction of the membrane. This achieves the gradient already mentioned. The sintered layers may be connected to each other via grain boundaries, so that the sintered body can be treated as a single component, regardless of the layer structure. This facilitates the assembly of the cell.

[0041] Since the nickel-containing sintered body described herein is also suitable as a cathode, it is conceivable to manufacture not only the anode but also the cathode from the sintered catalytically active material. In a preferred development of the electrochemical cell, the cathode is therefore partially or entirely configured as a second porous sintered body comprising grains fused to one another at the grain boundaries.

[0042] In order to distinguish between a sintered body used as a cathode and a sintered body used as an anode, in this specification, the term "first porous sintered body" is used for the anode, and the term "second porous sintered body" is used for the cathode.

[0043] On the cathode side, the integration of catalytic activity into the sintered material is not necessarily required. However, it is preferred that a catalytically active material is also used in the second sintered body. The same material as on the anode side is suitable. In the simplest case, the same material is used on both the anode and cathode side. However, this does not necessarily have to be the case. It is therefore appropriate to distinguish between a first sintered body and a second sintered body. The cathode is preferably constructed as a porous sintered body overall.

[0044] The second porous sintered body not only performs the electrochemical function of being a cathode but also functions as a porous transport layer.

[0045] The electrochemical cell can be configured in two variations on the cathode side: In the first variant, the cathode (hydrogen side, in particular configured as a second porous sintered body) is in direct contact with the membrane. If the membrane in this case itself is not coated with a catalytically active material (electrocatalyst), then catalytically active substances must be applied to the cathode or the cathode material itself must be catalytically active.

[0046] In a second variation, a catalytically active layer (electrocatalyst) is arranged between the cathode (hydrogen side, in particular configured as a second porous sintered body) and the membrane. The particles forming the second sintered body do not necessarily have to be catalytically active or coated with catalytically active material. In this case, the particles of the second sintered body must simply be conductive to allow electrical contact between the catalytically active layer (electrocatalyst) and the flow field or the bipolar plate. This structure is advantageous when using electrocatalysts that cannot be integrated into the particles or that cannot be generated, or that cannot be applied with permanent stability to the second porous sintered body, or that have a higher catalytic activity than the sintered material itself or than the catalytically active material formed on the particle surface during operation of the electrolytic cell.

[0047] As already mentioned, the variant of the invention having a catalytic layer between the cathode and the membrane has the advantage that it can contain electrocatalysts that are not easily applied to the second sintered body.The catalytic layer can thus contain catalytically active particles (electrocatalysts) containing elements such as Pt, Ru, Pd, C, Ni, Mn, Mo, Co, Cu, Fe, Cr, etc.

[0048] It is particularly advantageous if the catalytically active particles of the electrocatalyst are embedded in an anion-conducting polymer. In this case, the catalyst layer consists at least of the catalytically active particles and an anion-conducting polymer. The ion-conducting polymer is called an ionomer. By embedding the catalytically active particles in an anion-conducting ionomer, the hydroxide ions generated during the reduction of water at the cathode can be conducted to the membrane immediately after the reaction. It is particularly preferred if the anion-conducting polymer has very good adhesion to the membrane surface and conducts the hydroxide ions very well. In that case, a particularly effective integration of the catalyst particles with the membrane and a particularly good ionic bond between the catalyst particles and the membrane are obtained.

[0049] However, in contrast to known CCM designs (membranes coated on both sides with electrocatalyst), the membranes of the present structure are provided with a catalyst layer only on the cathode hydrogen-producing side. The anode oxygen-producing side does not have any catalyst layer, and the electrocatalyst is integrated into the sintered anode material on the oxygen side. Thus, the variant with a catalyst layer only on the cathode side can be considered a "half CCM cell".

[0050] The separation active material forming the anion-conducting membrane is also an anion-conducting ionomer. In principle, all anion-conducting ionomers can be incorporated into the electrochemical cell of the invention, where they can act as a separation active membrane material and / or can be used to immobilize catalytically active particles.

[0051] In a preferred embodiment of the invention, the membrane comprises the same anion conducting polymer as the catalytically active coating that anchors the catalyst on the hydrogen side. The ionomer in the catalyst layer and the ionomer in the membrane should at least have the same repeating units in the anion conducting polymer, although the chain lengths may differ.

[0052] Particularly preferred is the use of anion-conducting polymers according to formula (I) or formula (II) or formula (III).

[0053] The common advantages of the ionomers of formula (I), (II) or (III) are good ionic conductivity, high swelling resistance in alkaline media, and low synthesis cost.

[0054] The ionomers of formula (I) or formula (II) or formula (III) can be used in the manufacture of membranes or as binders for fixing electrocatalysts in catalytically active layers or on inert sintered materials.

[0055] The anion conducting polymer of structural formula (I) is defined as follows:

[0056] [ka]

[0057] (Wherein, X is C 1 and C 2 and via two bonds to one or two hydrocarbon groups having 1 to 12, preferably 1 to 6, more preferably 1 or 5 carbon atoms; Z is C 3 and C 4 and having at least one aromatic six-membered ring bonded directly to one of the oxygen atoms, the aromatic six-membered ring containing one or more halogen groups and / or one or more C 1 ~C 4It may be substituted with an alkyl group.

[0058] The preparation of ionomers of structural formula (I) is described in WO 2021 / 013694.

[0059] The anion conducting polymer of structural formula (II) is defined as follows:

[0060] [ka]

[0061] (Wherein, X is C 1 and C 2 and via two bonds to one or two hydrocarbon groups having 1 to 12, preferably 1 to 6, more preferably 1 or 5 carbon atoms; Z is C 3 and C 4 and at least one aromatic six-membered ring bonded directly to one of the oxygen atoms, the aromatic six-membered ring being bonded at the 3- and 5-positions with the same or different C 1 ~C 4 It may be substituted with an alkyl group, in particular a methyl group, an isopropyl group or a tert-butyl group, preferably a methyl group.

[0062] The preparation of ionomers of structural formula (II) is described in EP 4032934 A1.

[0063] The anion conducting polymer of structural formula (III) is defined as follows:

[0064] [ka]

[0065] (In the formula, X is a ketone group or a sulfone group. Z is an entity having at least one tertiary carbon atom and at least one six-membered aromatic ring that is directly bonded to one of the two oxygen atoms. Y is a moiety that contains at least one positively charged nitrogen atom, which is bonded to the moiety Z.

[0066] The preparation of ionomers of structural formula (III) is described in EP 4059988 A1.

[0067] Regardless of whether the electrochemical cell is equipped with one or two porous sintered bodies (electrodes), it is advantageous if the first and / or second sintered body is in contact with the bipolar plate on the side remote from the membrane. "Contact" does not only have a purely mechanical meaning, but also an electrical meaning, since the bipolar plate is electrically conductive. The contact is preferably made over the entire area. More preferably, a direct contact is envisaged, in which case no additional material is incorporated between the electrode and the bipolar plate in the cell. This makes the cell particularly compact and cost-effective. The fluid-conducting function of the porous sintered body is then optimally used. The bipolar plate can be used to make electrical contact with the adjacent electrochemical cell. This allows several electrochemical cells to be connected in series and stacked (see below) to save space.

[0068] The bipolar plates preferably comprise one of the following materials: nickel; nickel-containing alloys such as Hastelloy, Cronin, Monel, Inconel, Incoloy, Invar, Kovar; nickel-containing steel; nickel-containing stainless steel; AISI301, AISI301L, AISI304, AISI304L, AISI310, AISI310L, AISI316, AISI316L, AISI317, AISI317L and AISI321 type steels, nickel-plated steel, nickel-plated stainless steel, nickel-plated titanium, nickel-plated brass, nickel-plated aluminum, nickel-plated acrylonitrile butadiene styrene copolymer, and carbon.

[0069] The electrochemical cell presented herein is optimized for use in alkaline water electrolysis (AEM water electrolysis). Accordingly, the present invention provides a method for producing hydrogen and oxygen by electrochemical decomposition of water comprising the steps of: a) providing at least one electrochemical cell having an anode, a cathode, and an anion-conducting membrane disposed between the anode and the cathode, the anode being at least partially configured as a first porous sintered body comprising grains fused at grain boundaries, the first porous sintered body being in direct contact with the membrane; b) providing an aqueous electrolyte having a pH between 7 and 15; c) providing a voltage source; d) contacting the first sintered body and / or the cathode with an electrolyte; e) applying a voltage derived from a voltage source to the anode and the cathode; f) discharging the oxygen gas and / or the electrolyte containing dissolved oxygen from the first porous sintered body; g) evacuating the hydrogen gas and / or hydrogen-dissolved electrolyte from the electrochemical cell; h) optionally separating oxygen from the electrolyte discharged from the first porous sintered body; i) Optionally, separating hydrogen from the electrolyte discharged from the cell.

[0070] The electrolyte used contains water to be electrolyzed. The pH of the electrolyte is adjusted to the basic region (pH 7 to pH 15) by adding an alkaline substance such as NaOH or KOH to the water. The water in the electrolyte is thus decomposed by water electrolysis and is continuously supplied to the electrolyte.

[0071] The method can be operated in two variations: wet and semi-dry. In the wet mode, both compartments are filled with electrolyte. In the semi-dry mode of operation, only one of the two compartments, the anode side (situation 1) or the cathode side (situation 2), is filled with electrolyte.

[0072] In the wet version, both compartments on either side of the membrane are immersed in an aqueous basic electrolyte. Hydrogen is stored in the aqueous electrolyte on the cathode side, and oxygen is stored on the anode side. If the gas does not spontaneously bubble out of the electrolyte, the electrolyte is evacuated from both compartments, removing the gas of interest.

[0073] In practice, a mixed form may be possible in which part of the generated gas spontaneously escapes from the porous sintered body and another part remains dissolved in the water and must be separated in a separate operation.

[0074] Unlike the wet method, in the semi-dry method, either only the anode side (anode, situation 1) or only the cathode side (cathode, situation 2) is immersed in the basic electrolyte. The cathode or anode compartment remains dry. From there, hydrogen gas or hydrogen-enriched basic electrolyte or oxygen gas or oxygen-enriched basic electrolyte is extracted from the second porous sintered body (cathode) or the first porous sintered body (anode). In situation 1, oxygen accumulates in the anode compartment filled with basic electrolyte, as in the wet method. In situation 2, hydrogen accumulates in the cathode compartment filled with basic electrolyte, as in the wet method.

[0075] The advantage of the two semi-dry variants is that the gas produced contains almost no water, since the corresponding electrodes are not immersed in the basic electrolyte, and there is no need to separate the basic electrolyte from hydrogen (situation 1) or oxygen (situation 2). The basic idea of ​​the semi-dry AEM method (situation 1), where there is water only on the anode side, is described in WO 2011 / 004343.

[0076] Therefore, in the semi-dry method (case 1), there is no need to soak the second porous sintered body and separate the hydrogen: the generated hydrogen is directly present in gaseous form in the cathode compartment.

[0077] In fact, in situation 1, a mixed form is also conceivable, where part of the oxygen spontaneously escapes from the first porous sintered body, while another part remains dissolved in the water and needs to be separated therefrom in a separate operation. However, if the only objective is to recover hydrogen, the separation of oxygen from the electrolyte removed from the first porous sintered body can be omitted; the oxygen remains in the electrolyte. This procedure is particularly energy-efficient, since it is not necessary to separate hydrogen and oxygen from the electrolyte.

[0078] If the electrolysis is carried out such that only the cathode side (cathode, situation 2) is immersed in the basic electrolyte, the separate separation of the oxygen can be omitted. In fact, even in situation 2, a mixed form is conceivable in which part of the hydrogen spontaneously escapes from the first porous sintered body and another part remains dissolved in the electrolyte and has to be separated therefrom in a separate operation.

[0079] Common to all method variants presented herein is the use of the porous structure of the sintered body to guide the reactants to the catalytically active centers of the electrocatalyst. According to the invention, the porous sintered body performs the function of a fluid conductor in all cases. Depending on the embodiment (wet, semi-dry situation 1, semi-dry situation 2), the fluid guided in the porous sintered body is a liquid electrolyte, a liquid electrolyte with dissolved hydrogen, a liquid electrolyte with dissolved oxygen, oxygen gas or hydrogen gas. Moreover, the fluid may include several phases composed of the aforementioned gases and liquids.

[0080] A particular advantage of the electrochemical cell structure presented herein is that it can be used for a variety of process variations without modification of the structure. As a result, electrochemical cell manufacturers only need to produce one cell design, and cell users can determine which process variation (wet, semi-dry, etc.) is most cost-effective for their application. The reduced complexity can significantly reduce the manufacturing costs of the cell.

[0081] All process variants presented herein are preferably carried out continuously, i.e. aqueous basic electrolyte is continuously fed and gas or oxygen-enriched and / or hydrogen-enriched electrolyte is continuously removed. The continuous electrolyte feed compensates for the loss of water due to electrolysis, which would otherwise be completely electrolyzed over time and electrolyte lost. The electrochemical reaction would then cease. A batch process is conceivable, but not preferred on an industrial scale, in which the electrochemical cell is completely, or at least its anode compartment, filled with electrolyte and the electrolyte is electrolyzed until the cell or anode compartment is empty.

[0082] The method of the invention is preferably carried out in an electrolytic cell comprising at least two electrochemical cells of the invention sharing a common bipolar plate, i.e. the bipolar plate is simultaneously in contact with the anode of a first electrochemical cell of the electrolytic cell and with the cathode of a second electrochemical cell of the electrolytic cell, in which case two adjacent cells are connected in series. The invention also provides such an electrolytic cell.

[0083] The advantage of an electrolyser in which adjacent cells share a bipolar plate is its compact stack structure and therefore its small size. Preferably, the electrolyser comprises more than two adjacent cells sharing a common bipolar plate. Depending on the size of the individual electrochemical cells and the required power output, it is possible to stack up to 250 cells in one electrolyser via the bipolar plates.

[0084] A further advantage of the electrolytic cell of the present invention is that it can be manufactured with a high degree of automation, since the individual components of the electrochemical cell can be stacked very efficiently by robots, which can further reduce the manufacturing costs of the electrolytic cell.

[0085] The invention also provides a method for the manufacture of an electrolytic cell comprising at least two electrochemical cells according to the invention sharing a common bipolar plate, during which the following components are directly stacked in the following order:

[0086] In the sequence of events for this method, the stacking is performed from anode to cathode. a) first porous sintered body; b) Anion conducting membrane. c) a catalyst layer, if necessary; d) cathode; e) bipolar plates; f) a first porous sintered body; g) an anion conducting membrane; h) a catalyst layer, if necessary; i) Cathode.

[0087] It is also possible to stack from cathode to anode, in which case the stacking order would be: a) Cathode b) a catalyst layer, if necessary; c) an anion conducting membrane; d) a first porous sintered body; e) bipolar plates; j) cathode; k) optionally a catalyst layer; l) an anion conductive membrane, m) first porous sintered body;

[0088] Both stacking sequences result in identical electrolytic cells. In accordance with the present invention, the stacking sequence can be repeated to contact more than two adjacent cells of the present invention with each other via a common bipolar plate. For each run, a bipolar plate needs to be inserted.

[0089] For example, if three cells are stacked from anode to cathode, the stacking order is as follows: a) first porous sintered body; b) an anion conducting membrane; c) a catalyst layer, if necessary; d) cathode; e) bipolar plates; f) a first porous sintered body; g) an anion conducting membrane; h) a catalyst layer, if necessary; i) a cathode, j) bipolar plates; k) first porous sintered body; l) an anion conductive membrane, m) a catalyst layer, if necessary; n) Cathode.

[0090] All stacks may have end plates at either end of the stack, constructed like bipolar plates but connected in a monopolar fashion.

[0091] The stacking is preferably performed automatically, in particular using a robot.

[0092] The production of electrolytic cells is particularly efficient if the first and second sintered bodies consist of the same material. It is especially preferred if the same sintered body is used for both anode and cathode. In this case, the number of different components is reduced, the assembly speed increases and the cost of the electrolytic cell is reduced. Again, the stacking process can be better carried out using a robot, since the robot does not have to distinguish between anodes and cathodes and instead only has to install one type of sintered body as an electrode. In this case, it does not matter whether the stacking is done from cathode to anode or vice versa.

[0093] The present invention further provides an application of the electrochemical cell in alkaline membrane water electrolysis.

[0094] The invention will now be illustrated by examples. In this respect, the figures show: FIG. 1a: Schematic diagram of the design of a first embodiment of an electrochemical cell. FIG. 1b: Schematic diagram of the operation of the first embodiment of the electrochemical cell (FIG. 1a) in the wet method variant. FIG. 1c: Schematic diagram of the operation of the first embodiment of the electrochemical cell (FIG. 1a) in the semi-dry variant (case 1-"dry cathode") FIG. 1d: Schematic diagram of the operation of the first embodiment of the electrochemical cell (FIG. 1a) in the semi-dry method variant (situation 2 - "dry anode") FIG. 2a: Schematic diagram of the design of a second embodiment of an electrochemical cell. FIG. 2b: Schematic diagram of the operation of the second embodiment of the electrochemical cell (FIG. 2a) in the wet method variant. FIG. 2c: Schematic diagram of the operation of the second embodiment of the electrochemical cell (FIG. 2a) in the semi-dry variant (situation 1 - "dry cathode") FIG. 2d: Schematic diagram of the operation of the second embodiment of the electrochemical cell (FIG. 2a) in the semi-dry method variant (situation 2 - "dry anode") FIG. 3: schematic diagram of an operational variant of an electrolytic cell comprising two electrochemical cells according to the first embodiment (FIG. 1a) FIG. 4: Schematic diagram of the design of an electrolytic cell including two electrochemical cells according to the second embodiment (FIG. 2a).

[0095] Figure 1a shows diagrammatically in cross section a first embodiment of an electrochemical cell 0. It comprises an anode 1, a cathode 2 and an anion conducting membrane 3 arranged between the anode 1 and the cathode 2. The anode 1 and the cathode 2 are each constructed as a porous sintered body. The porosity is, by way of example, 38%. They can be homogeneously distributed in the sintered body or follow a gradient such that the porosity increases with distance from the membrane 3.

[0096] Membrane 3 is a flat membrane made of an anion conducting polymer. Membrane 3 divides electrochemical cell 0 into two compartments: an anode compartment on the anode 1 side and a cathode compartment on the cathode 2 side. Anode 1 and cathode 2 are each directly adjacent to membrane 3. On the side remote from membrane 3, anode 1 and cathode 2 are each in contact with end plate 4.

[0097] The active areas of the anode 1 and cathode 2 extend perpendicular to the plane of the drawing.

[0098] The embodiment of the electrochemical cell 0 shown in FIG. 1a does not have a separate flow distribution device, or a separate porous transport layer (PTL), or a separate catalytically active catalyst layer. The function of the PLT is taken over by the anode 1 and cathode 2 themselves, since they are composed of porous sintered bodies that are fluid conductive. However, the flow distribution device may also be integrated into the end plates 4 (not shown). The compartments of the cell are thus composed only of the respective sintered bodies 1, 2. The sintered material contains nickel and iron. In the simplest case, the material that constitutes the particles is stainless steel, which usually contains nickel and iron. During the operation of the cell, the oxidation of nickel and iron produces catalytically active mixed Ni-Fe oxides or mixed Ni-Fe hydroxides. As a result, no additional catalyst layers are needed, since the sintered material is catalytically active.

[0099] Electrochemical cell 0 allows for three operating modes: wet, semi-dry situation 1, and semi-dry situation 2.

[0100] Figure 1b shows diagrammatically the operation of the electrochemical cell of Figure 1a in the wet process variant. During electrolysis operation, the anode 1 and the cathode 2 are immersed and permeated with water or a basic electrolyte.

[0101] Figure 1c shows a semi-dry method variant in which only the anode 1 of the electrochemical cell 0 of Figure 1a is immersed and permeated with water or basic electrolyte during electrolysis operation (semi-dry situation 1). The cathode 2 remains dry.

[0102] Figure 1d shows a semi-dry method variant in which only the cathode 2 of the electrochemical cell 0 of Figure 1a is immersed and permeated with water or basic electrolyte during electrolysis operation (semi-dry situation 2). The anode 1 remains dry.

[0103] FIG. 2a shows a schematic design of a second embodiment of an electrochemical cell 0 in cross section. It comprises an anode 1, a cathode 2 and an anion-conducting membrane 3 arranged between the anode 1 and the cathode 2. The anode 1 and the cathode 2 are each constructed as a porous sintered body composed of nickel-containing particles. The membrane 3 is a flat membrane made of an anion-conducting ionomer and divides the cell 0 into two compartments. The two electrodes (anode 1 and cathode 2) are directly adjacent to the membrane 3. On the side remote from the membrane 3, the anode 1 and the cathode 2 are each in contact with an end plate 4.

[0104] The second embodiment is characterized by a catalytic layer 5 arranged between the cathode 2 and the membrane 3. The catalytic layer 5 may be applied to the cathode side of the cathode 2 and / or the membrane 3. The catalytic layer 5 is therefore present in the cathode compartment. It comprises catalytically active particles (electrocatalysts) fixed by an ionomer on the cathode 2 or on the membrane 3. The catalytically active particles are metal particles or alloys or coatings or compounds including Au, Pt, Rh, Ru, Pd, Ag, Ni, Co, Cu, Fe, Mn, Mo, for example sulfides, selenides, oxides, mixed oxides, hydroxides, mixed hydroxides, spinels or perovskites with particle sizes or coating thicknesses between 1 nm and 10 μm. The catalytically active particles present in the catalytic layer 5 may be unsupported or may be supported by carbonaceous materials (such as carbon black or charcoal) or oxides (CeO 2 , TiO 2 The concentration of the electrocatalyst is 0.01 mg / cm2 of the membrane or electrode area (cathode 2). 2 ~25mg / cm 2 , preferably 0.05 mg / cm 2 ~5mg / cm 2The thickness of the catalyst layer containing the particles is between 1 μm and 500 μm, preferably between 5 μm and 100 μm. The ionomer is the same material from which the membrane 3 is made. When the catalyst layer 5 is applied to the membrane 3, the resulting structure is a "catalyst coated membrane" (CCM). When the catalyst layer 5 is applied to the cathode 2, the resulting structure is a "catalyst coated substrate" (CCS). Based solely on the schematic diagram in FIG. 2a, it is not possible to determine whether a variation of a CCM or a CCS is depicted.

[0105] Electrochemical cell 0 of FIG. 2a similarly allows three modes of operation: wet, semi-dry regime 1, and semi-dry regime 2.

[0106] FIG. 2b shows a wet process variant in which the anode 1 and cathode 2 are immersed and permeated with water or a basic electrolyte during electrolysis operation.

[0107] FIG. 2c shows a semi-dry method variant in which only the anode 1 is immersed and permeated with water or basic electrolyte during the electrolysis operation (semi-dry situation 1). The cathode 2 remains dry.

[0108] Figure 2d shows a semi-dry method variant where only the cathode 2 is immersed and permeated with water or basic electrolyte during the electrolysis operation (semi-dry situation 2). The anode 1 remains dry.

[0109] 3 shows diagrammatically a first embodiment of an electrolytic cell 6 in wet operation. The electrolytic cell 6 comprises two adjacent electrochemical cells 0 according to a first embodiment, having an identical structure and in contact via a common bipolar plate 7.

[0110] To perform water electrolysis using the first electrolytic cell 6, all electrodes are immersed and continuously permeated with water or a basic electrolyte during the electrolysis operation. This mode of operation corresponds to a variant of the method described above as "wet", since all sintered bodies are immersed and permeated with water or a basic electrolyte. A voltage acting between the anode 1 and the cathode 2 is then applied to each cell. This effect, according to the principles described above, is the electrolysis of water and the associated hydrogen (H2 ) in the porous sintered body forming the anode 1 and 2 ) and the release of oxygen (O 2 ), hydrogen (H 2 ), and undecomposed water (H 2 O) or basic electrolyte is withdrawn from the anode 1 and the cathode 2 accordingly, and water or basic electrolyte is pumped continuously through the anode 1 and the cathode 2.

[0111] 4 shows diagrammatically a second embodiment of an electrolytic cell 8 in operation. The second electrolytic cell 8 comprises two adjacent electrochemical cells 0 according to the second embodiment, which have an identical structure and are in contact via a common bipolar plate 7.

[0112] To perform water electrolysis using the second electrolytic cell 8, during the electrolysis operation, all electrodes are immersed and permeated with water or a basic electrolyte. This mode of operation corresponds to a variant of the method described above as "wet", since both sintered bodies are immersed in water or a basic electrolyte. A voltage acting between the anode 1 and the cathode 2 is then applied to each cell. This effect, according to the principles described above, is the electrolysis of water and the associated generation of hydrogen (H 2 ) in the porous sintered body forming the anode 1, and 2 ) and the release of oxygen (O 2 ), hydrogen (H 2 ), and undecomposed water (H 2 O) or basic electrolyte is withdrawn from the anode 1 and the cathode 2 accordingly, and water or basic electrolyte is pumped continuously through the anode 1 and the cathode 2. [Brief description of the drawings]

[0113] [Figure 1a] FIG. 1 is a schematic diagram of the design of a first embodiment of an electrochemical cell. [Figure 1b] FIG. 1A is a schematic diagram of the operation of a first embodiment of an electrochemical cell (FIG. 1a) in the wet method variant. [Figure 1c]FIG. 1A is a schematic diagram of the operation of a first embodiment of an electrochemical cell (FIG. 1a) in the semi-dry method variant (case 1—“dry cathode”). [Figure 1d] FIG. 1B is a schematic diagram of the operation of a first embodiment of an electrochemical cell (FIG. 1a) in the semi-dry method variant (case 2—“dry anode”). [Figure 2a] FIG. 2 is a schematic diagram of the design of a second embodiment of an electrochemical cell. [Figure 2b] FIG. 2B is a schematic diagram of the operation of a second embodiment of an electrochemical cell (FIG. 2a) in the wet process variant. [Figure 2c] FIG. 2B is a schematic diagram of the operation of a second embodiment of an electrochemical cell (FIG. 2a) in the semi-dry method variant (case 1—“dry cathode”). [Figure 2d] FIG. 2b is a schematic diagram of the operation of a second embodiment of an electrochemical cell (FIG. 2a) in the semi-dry method variant (situation 2—“dry anode”). [Diagram 3] FIG. 1 is a schematic diagram of an operational variant of an electrolytic cell comprising two electrochemical cells according to the first embodiment (FIG. 1a). [Figure 4] FIG. 2 is a schematic diagram of the design of an electrolytic cell comprising two electrochemical cells according to a second embodiment (FIG. 2a). [Diagram 5] 1 is a current-voltage curve of Experimental Example 1. [Figure 6] 1 shows current-voltage curves of Experimental Example 2 and Experimental Example 1. EXAMPLES

[0114] The effects achieved by the present invention are explained below with reference to experimental data. For this purpose, the porous sintered body is used as an anode material in an electrolysis test cell for AEM water electrolysis. For comparison, nickel foam was used as the anode material.

[0115] 1. Preparation of the Ionomer (not part of this invention) The anion conducting polymer was synthesised according to Example 3 of EP 3770201 A1.

[0116] 2. Preparation of anion conducting membrane (not part of this invention) Membranes were then prepared from the anion conducting polymer synthesized in 1 as described in Example 4 of EP 3770201. Fresh membrane pieces that had been ion exchanged in 1 M KOH at 60° C. for 24 h were used in each experiment.

[0117] 3. Preparation of Active Test Cathode (not part of this invention) An ink was made from platinum on carbon (60 wt% platinum on carbon, product number AB204745, abcr GmbH, Germany) by adding first 44 parts water, then 44 parts ethanol, and finally 5 parts ionomer solution (5% of the ionomer made in 1. dissolved in DMSO) per part by weight of platinum-based catalyst, shaking the ink and dispersing it by ultrasonic treatment for 30 minutes.

[0118] For the preparation of the cathode, a carbon fiber nonwoven fabric (TGP-H120, thickness = 370 μm, porosity = 78%, sample name "Carbon fiber nonwoven fabric", Toray Industries, Inc., Japan) was selected as the substrate. The substrate was coated with the Pt / C-containing ink of the preparation method described above using a Prism 400 ultrasonic spray coater (Ultrasonic Systems, Inc., Haverhill, Massachusetts, USA). The loading of platinum (Pt) was 0.6 mg / cm. 2 It was.

[0119] 4. Electrolyte measurement of test cell A diagram of the electrolytic test cell is shown in Figure 2a. All experimental examples were carried out on a 16 cm2 electrochemical cell with an anode 1, a cathode 2, a membrane 3 and an active area of ​​16 cm2. 2 The experiment was carried out in an electrochemical cell 0 having two end plates 4 of 0.1 μm and 0.2 μm. A component of the cathode 2 is the above-mentioned catalytic coating 5. The cathode 3 is therefore a catalytically coated substrate (CCS).

[0120] The end plate 4 contains a flow field in the form of elongated channels 1.5 mm wide with one inlet and one outlet per channel (this is not shown in FIG. 2a).

[0121] The electrolyte used was 1 M KOH, which was pumped at 50 mL / min through anode 1 and cathode 2. All experiments were carried out at 60° C., allowing thermal equilibration of the electrolyte only. The individual characteristics of each example experiment are described separately.

[0122] Experimental Example 1 (Inventive) A porous sintered body (SAE316L steel, thickness = 1.57 mm, porosity = 38%, sample designation "sintered body") was used as the anode and had no catalytic coating. This sintered body acts not only as a porous transport layer but also as the active (anode) catalytic material. Figure 5 shows the current-voltage curves recorded using the electrolytic test cell described above. Figure 5: Current-voltage curves for Experimental Example 1

[0123] Using sintered bodies without additional anode side catalytic coating, up to 1.5A / cm at less than 1.9V 2 This means that the efficiency is high when used industrially.

[0124] Experimental Example 2 (Non-inventive) For this purpose, a foam made of nickel (product code: NI00-FA-000152, thickness = 1.6 mm, porosity = 95%, Goodfellow, UK, sample designation "Foam") was used as the anode without any additional catalytic coating. This sintered body acts simultaneously as a porous transport layer and as the active (anode) catalytic material. In Figure 6, the current-voltage curve recorded with the nickel foam anode is shown in dotted line. The solid line is the current-voltage curve recorded with the sintered steel anode of Figure 5. Figure 6: Current-voltage curves for Experimental Example 2 and Experimental Example 1

[0125] It can be seen that the use of nickel foam (dotted line) allows a much higher voltage to be reached than the use of sintered body (solid line). For example, it takes 1.5 A / cm to reach 2.15 V. 2The current density of 1000 kW is not reached. This relatively high voltage means that the efficiency in use is very low. In industrial terms, this means that more energy (>10%) needs to be consumed to produce the same amount of hydrogen.

[0126] conclusion Comparing the two experimental examples, it is clear that the use of sintered bodies as anode materials for AEM water electrolysis leads to significant efficiency improvements compared to foam electrodes.

[0127] Reference List 0 Electrochemical Cell 1 First porous sintered body (anode) 2 Second porous sintered body (cathode) 3 Anion conductive membrane 4 End Plate 5 Catalyst layer 6 Electrolytic cell according to a first embodiment, comprising two adjacent electrochemical cells 0 in contact via a common bipolar plate 7 7 Bipolar Plates 8 Electrolytic cell according to a second embodiment, comprising two adjacent electrochemical cells 0 in contact via a common bipolar plate 7 H 2 O Water or alkaline electrolytes H 2 hydrogen O 2 oxygen

Claims

1. The present invention relates to a fuel cell comprising an anode (1), a cathode (2), and an anion conductive membrane (3) disposed between the anode (1) and the cathode (2), The anode (1) is partially or entirely configured as a first porous sintered body (1) comprising grains fused together at grain boundaries, The first porous sintered body (1) is in direct contact with the membrane (3), thereby forming an electrochemical cell (0) for alkaline membrane water electrolysis.

2. The particles of the first porous sintered body (1) contain a catalytically active material or contain only a catalytically active material; 2. The electrochemical cell (0) of claim 1, wherein the catalytically active material comprises at least one transition metal selected from the list comprising the transition metals Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Ac, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg.

3. 3. The electrochemical cell (0) according to claim 1 or 2, wherein the particles of the first porous sintered body (1) contain nickel.

4. 4. The electrochemical cell (0) according to claim 3, wherein the particles of the first porous sintered body (1) comprise a material selected from the group comprising nickel, nickel-containing alloys, Hastelloy, Cronin, Monel, Inconel, Incoloy, Invar, Kovar, nickel-containing steels, nickel-containing stainless steels, and steels of AISI 301, AISI 301L, AISI 304, AISI 304L, AISI 310, AISI 310L, AISI 316, AISI 316L, AISI 317, AISI 317L and AISI 321 type.

5. The electrochemical cell (0) according to any one of claims 1 to 4, wherein no catalyst layer is disposed between the first porous sintered body (1) and the membrane (3).

6. The porosity P of the first porous sintered body (1) is 5% to 60%, or 15% to 45%, and the porosity P is represented by the formula: P=1-ρ Ｖ / r Ｍ (In the formula, ρ Ｖ is the volume density of the first porous sintered body (1), and ρ Ｍ is the solid density of the particles of the first porous sintered body (1). The electrochemical cell (0) according to any one of claims 1 to 5, wherein the electrochemical cell (0) is measured according to

7. 7. The electrochemical cell (0) according to claim 6, wherein the porosity P varies along a gradient, the gradient being arranged perpendicular to an interface between the first porous sintered body (1) and the membrane (3), and the porosity P decreasing in the direction of the membrane (3).

8. The electrochemical cell (0) according to any one of claims 1 to 7, wherein the pores of the first porous sintered body (1) are smaller than the grains of the first porous sintered body (1) when determined by cross-sectional observation with an optical microscope.

9. The electrochemical cell (0) according to any one of claims 1 to 8, wherein the cathode (2) is partially or entirely constructed as a second porous sintered body (2) comprising grains fused to one another at grain boundaries.

10. The particles of the second porous sintered body (2) contain a catalytically active material or contain only a catalytically active material; 10. The electrochemical cell (0) of claim 9, wherein the catalytically active material comprises at least one transition metal selected from the list comprising the transition metals Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Ac, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg.

11. 11. The electrochemical cell (0) according to claim 9 or claim 10, wherein the particles of the second porous sintered body (2) comprise nickel.

12. 12. The electrochemical cell (0) of claim 11, wherein the particles of the second porous sintered body (2) comprise a material selected from the group comprising nickel, nickel-containing alloys, Hastelloy, Cronin, Monel, Inconel, Incoloy, Invar, Kovar, nickel-containing steels, nickel-containing stainless steels, and steels of AISI 301, AISI 301L, AISI 304, AISI 304L, AISI 310, AISI 310L, AISI 316, AISI 316L, AISI 317, AISI 317L and AISI 321 type.

13. Electrochemical cell (0) according to any one of the preceding claims, wherein the catalyst layer (5) is arranged between the cathode (2) and the membrane (3).

14. 14. The electrochemical cell (0) of claim 13, wherein the catalyst layer (5) comprises at least one element or compound of elements selected from the group comprising Pt, Ru, Pd, C, Ni, Mo, Co, Cu, Fe, Cr.

15. Electrochemical cell (0) according to claim 13 or claim 14, wherein the catalyst layer (5) comprises an anion conducting polymer.

16. 16. The electrochemical cell (0) of claim 15, wherein the anion conducting polymer comprises repeat units that are also comprised in the membrane (3).

17. The electrochemical cell (0) according to any one of claims 1 to 16, wherein the first porous sintered body (1) and / or the second porous sintered body (2) are in contact with a bipolar plate (7) on a side remote from the membrane (3).

18. 18. The electrochemical cell (0) of claim 17, wherein the bipolar plate (7) comprises a material selected from the group comprising nickel, nickel-containing alloys, Hastelloy, Cronin, Monel, Inconel, Incoloy, Invar, Kovar; nickel-containing steel, nickel-containing stainless steel, AISI 301, AISI 301L, AISI 304, AISI 304L, AISI 310, AISI 310L, AISI 316, AISI 316L, AISI 317, AISI 317L and AISI 321 type steels, nickel-plated steel, nickel-plated stainless steel, nickel-plated titanium, nickel-plated brass, nickel-plated aluminum, nickel-plated acrylonitrile butadiene styrene copolymer, and carbon.

19. Water (H ２ Hydrogen (H ２ ) and oxygen (O ２ ) a) providing at least one electrochemical cell (0) according to any one of claims 1 to 18; b) providing an aqueous electrolyte having a pH between 7 and 15; c) providing a voltage source; d) contacting the first sintered body (1) and / or the cathode (2) with the electrolyte; e) applying a voltage drawn from the voltage source to the anode (1) and the cathode (2); f) Oxygen gas (O ２ ) and / or oxygen (O ２ Discharging the electrolyte in which the electrolyte has dissolved; g) Hydrogen gas (H ２ ) and / or hydrogen (H ２ Discharging the electrolyte in which the electrolyte has dissolved; h) If necessary, oxygen (O ２ ) from the mixture; i) If necessary, hydrogen (H ２ and separating said fluororesin from said fluororesin.

20. 20. An electrolytic cell (6, 8) for carrying out a method according to claim 19, comprising at least two electrochemical cells (0) according to claim 17 sharing a common bipolar plate (7).

21. The following components: a) first porous sintered body (1), b) an anion conductive membrane (3); c) optionally a catalyst layer (5); d) cathode (2), e) bipolar plate (7); f) first porous sintered body (1), g) anion conductive membrane (3), h) optionally a catalyst layer (5); i) Cathode (2) 21. A method for producing an electrolytic cell (6, 8) according to claim 20, characterized in that, during the production process,

22. The following components: a) a cathode (2); b) optionally a catalyst layer (5); c) anion conductive membrane (3); d) first porous sintered body (1), e) bipolar plate (7); f) cathode (2), g) optionally a catalyst layer (5); h) anion conductive membrane (3), j) First porous sintered body (1) 21. A method for producing an electrolytic cell (6, 8) according to claim 20, characterized in that, during the production process,

23. Use of the electrochemical cell (0) according to any one of claims 1 to 16 in alkaline membrane water electrolysis.

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