Anion-conductive membrane, a method for manufacturing said membrane, an electrochemical cell comprising said membrane, and equipment comprising said cell

Abstract

The present invention relates to a catalytic material layer for an anion-conducting membrane (10) for an electrochemical device; the catalytic material layer comprises metal nanoparticles bonded by a polymer binder. In one embodiment, the metal nanoparticles comprise a mixture of nickel nanoparticles and cobalt nanoparticles. The present invention also relates to a membrane comprising a catalytic material layer, and a method for manufacturing and depositing the catalytic layer.

Description

Technology Field

[0001] The technical field of the present invention relates to anion-conducting membranes, for example, anion-conducting membranes used in water electrolysis devices. More particularly, the present invention relates to a membrane for alkaline water electrolysis and a method for manufacturing said membrane. Background Technology

[0002] Hydrogen is used in many industrial processes, particularly as a starting material in the chemical industry and as a reducing agent in the metallurgical industry. Hydrogen is a fundamental element in the production of ammonia and consequent fertilizers, as well as in the production of methanol, which is used in the manufacture of many polymers. Oil refineries that use hydrogen for the processing of intermediate petroleum products are another area of ​​application.

[0003] Hydrogen is also an important energy carrier: it can store energy and supply it in a usable form. Energy is released through an exothermic combustion reaction with oxygen, in which water is formed. No carbon-containing greenhouse gases are emitted during this combustion reaction.

[0004] As electricity production from renewable energy increases, so does the need for energy storage and transport. Many renewable energy sources, particularly solar and wind power, are located far from densely populated areas and produce electricity only intermittently. Hydrogen can be the perfect carrier for renewable energy. Hydrogen can store energy and then distribute it to where and when it is needed.

[0005] Alkaline water electrolysis is an important method for producing hydrogen. In an alkaline water electrolysis cell, a membrane is used between the two electrodes, the cathode and the anode: the membrane separates the electron-conducting electrodes. Since the membrane is also non-porous to gases, it separates the gases generated at the electrodes, preventing the formation of an explosive mixture of gaseous hydrogen H2 (formed at the cathode) and gaseous O2 (formed at the anode). The membrane also [retains] OH - It is an ion conductor for transporting ions from the cathode to the anode.

[0006] The manufacture of proton-exchange membranes (PEMs) is well known. The most widely used membrane is the Nafion® membrane sold by DuPont de Nemours. The price of these membranes is very high. Furthermore, these membranes generate a highly acidic medium that severely corrodes the electrodes.

[0007] New membranes known as anion-exchange membranes (AEMs, or anion-conductive membranes) are being developed. For example, anionic membranes such as Piperion® and Sustainion®, and the separator Zirfon® may be mentioned. For example, Zirfon®, which is a porous separator rather than a conductive membrane, contains zirconium oxide particles bonded by a polymer. Membranes containing ceramic particles, such as the boron carbide membrane described in Document D1 = FR3122778 or the yttria-stabilized zirconia membrane described in Document D2 = FR3150048, may also be mentioned. Since these membranes are manufactured using polymers and metal oxide particles and / or ceramic particles, they are very simple to manufacture and less expensive. Furthermore, since these membranes are used in basic rather than acidic environments, it is permissible to use base metals for electrode fabrication—for example, using nickel for the cathode and stainless steel for the anode. However, all of these membranes and separators are generally less effective than catalyst-equipped membranes, which affects the profitability of large-scale hydrogen production.

[0008] To improve the efficiency of the membrane, it is known to deposit a catalytic layer based on rare materials, such as a catalytic layer based on platinum group metals, also known as PGM metals including iridium (Ir), osmium (Om), platinum (Pt), palladium (Pd), rhodium (Rh), and ruthenium (Ru), onto the membrane. Although the efficiency of the AEM membrane is improved, it is observed that in practice, the tolerance of the catalytic layer on the membrane is limited over time and is further influenced by the composition of the catalytic layer on the anode side and the cathode side and the method of deposition of such layer. Furthermore, since PGM metals are rare metals, the cost of the membrane increases significantly, and thus the profitability of large-scale hydrogen production decreases.

[0009] Description of the invention

[0010] The present invention proposes a novel catalyst layer and a novel membrane that do not have all or part of the aforementioned disadvantages.

[0011] To this end, the present invention proposes a novel catalytic material layer for anion-conducting membranes for electrochemical devices, said catalytic material layer comprising nanoparticles of an active component bonded by a polymer binder, said active component being nickel and cobalt.

[0012] Advantageously, the catalyst layer is deposited on the cathode side of the anion-conducting membrane.

[0013] The catalyst layer according to the present invention, deposited on the surface of the membrane, substantially improves the efficacy of the electrochemical reaction occurring at the interface between the membrane and the electrode, and the obtained result is generally more advantageous than when the catalyst is deposited on either side of the electrodes of a cell using an AEM membrane on which the catalyst is not deposited.

[0014] In addition, the obtained efficiency degrades much less over time.

[0015] Finally, since nickel and cobalt, which are metals used in the catalyst layer according to the present invention, are not rare materials, it is possible to manufacture a membrane having a catalyst layer at a reasonable cost, thereby enabling the large-scale production of hydrogen at a reasonable cost.

[0016] The present invention also relates to an anion-conducting membrane comprising at least one catalyst layer as described above, a cell comprising an anion-conducting membrane, and a water electrolysis unit comprising an anion-conducting membrane.

[0017] The present invention relates to a method for depositing a catalyst layer as described above onto an anion-conductive membrane. Brief explanation of the drawing

[0018] The present invention will be better understood and other features and advantages of the invention will become apparent through the following description of embodiments of the invention. These examples are given without implied limitation. The description should be understood with reference to the accompanying drawings, in which: [Fig. 1] shows a cell suitable for water electrolysis applications, [Fig. 2] shows a schematic diagram of a water electrolyzer, [Fig. 3] shows the size distribution of the components used for the implementation of the present invention, and [Fig. 4] shows an intermediate result for the method according to the present invention, and [Fig. 5] shows the results of a test performed using a catalytic material layer according to the present invention. Specific details for implementing the invention

[0019] As described above, the present invention relates to a catalytic material layer and an anion-conducting membrane (10) for an electrochemical device. The membrane may be used to manufacture a cell for an electrochemical device, for example, a water electrolysis unit; and the cell

[0020] - Anode (30),

[0021] - Cathode (20), and

[0022] - A membrane (10) between the anode and the cathode

[0023] Includes

[0024] The film also includes a known main layer. The main layer is, for example, a main layer containing particles of metal oxides such as zirconium oxide and yttrium oxide as described in D2, or a main layer containing ceramic particles as described in D1.

[0025] Unless otherwise specifically stated, the following terms are defined throughout this description. "Particle" is a collection of atoms or molecules of a single component or different components. The "size" of a particle corresponds to the largest dimension value of the particle; for example, the largest dimension of a particle with a substantially rhomboidal shape is the length of the particle. A given numerical value corresponds to an average value measured for an aggregate of particles of the same type. Measurement of the size of nanoparticles may be performed by scanning electron microscopy (SEM) or transmission electron microscopy (TEM). The term "nanoparticle" corresponds to a particle with an average size value of 1 to 100 nm. The expression "submicron particle" corresponds to a particle with an average size of 0.010 μm to 1 μm, and the term "microparticle" corresponds to a particle with an average size of 1 μm to 10 μm.

[0026] Unless otherwise specified, the term “nanoparticle” is used throughout this description to refer to particles with an average size value of 1 to 100 nm, said size defined as the largest dimension of the particle. Measurements of the nanoparticle size may be performed by scanning electron microscopy (SEM) or transmission electron microscopy (TEM). Each nanoparticle is a single component or a cluster of multiple atoms or molecules of different components.

[0027] To compare the performance of the membrane, the High Heating Value (HHV) efficiency R of a water electrolysis cell containing the membrane is calculated. To this end, the membrane is placed in a test cell, a current density I flowing between the cathode and anode per unit area of ​​the membrane is applied, and the voltage V(T, I) between the cathode and anode of the cell is measured.

[0028] For a given current density, it is sought to obtain the lowest possible voltage to achieve the dissociation of a given amount of water molecules.

[0029] The theoretical minimum voltage required to initiate the water dissociation reaction is V0 = 1.48 V HHV, which conventionally corresponds to an efficiency R of 100% HHV. The efficiency R is calculated by the equation R = V0 / V(T, I), where V(T, I) is the voltage at the terminals of the cell at a given temperature T and a given current density I.

[0030] Insofar as the heat generated by the electrolysis itself enables the system to maintain a constant temperature after raising the temperature, the above efficiency calculation appropriately reflects the efficiency of the cell. To calculate the overall efficiency of the electrolyzer including the cell, it will be necessary to subtract the amount of energy consumed for the overall operation of the system from the energy directly consumed by electrolysis. In this document, only the efficiency of the cell is analyzed.

[0031] One embodiment of the present invention relates to a catalytic material layer suitable for being disposed on the cathode side of the main layer of a membrane. The catalytic material layer comprises nanoparticles of an active component (in the sense of a catalyst for an electrolytic reaction) which is nickel, cobalt, or a mixture of nickel and cobalt.

[0032] The nanoparticles of the active ingredient used for carrying out the present invention can be purchased via mail order; for example, in the case of the tests performed, nickel, molybdenum, and cobalt nanoparticles were purchased from HEBEI Flance Nanotechnology Co. Ltd., a Chinese company.

[0033] The nanoparticles of the active ingredient are preferably supported by carbon particles and bonded by a polymer binder; the carbon exists in, for example, the form of activated carbon or graphite. The carbon particles preferably have a micrometer size (1 μm to 100 μm) or a submicrometer size (0.01 to 1 μm). The carbon particles are commercially available and can be purchased via mail order. For example, activated carbon particles can be purchased from Sigma Aldrich or Cabot Corp; for example, for a specific test, Vulcan XC-72R particles under the Vulcan brand from Cabot Corp were used; they have an average size of about 0.60 μm, and the size distribution of the aggregate of these particles is shown in Fig. 3.

[0034] In a mixture of carbon particles and nanoparticles of an active ingredient, the proportion of carbon per 100 wt% of the mixture is 40 wt% to 80 wt%, and the proportion of the active ingredient is 20 wt% to 60 wt%. When carbon particles are used to support the particles of the active ingredient, the specific surface area of ​​the catalytic material layer is further improved. Carbon, particularly activated carbon, possesses a high specific surface area itself. Applying the ratios indicated above, 250 m² 2 / g to 370 m 2 A catalyst layer having a specific surface area of ​​ / g is obtained. To reiterate, the specific surface area (or mass-based surface area) represents the total surface area per unit mass accessible to atoms and molecules for the reaction, including open pores. A universally accepted physical principle for determining the specific surface area is based on the adsorption of gases at low temperatures.

[0035] In addition, the use of carbon particles helps to facilitate the excellent distribution of nanoparticles of the active ingredient in the catalyst layer (Fig. 4) and further improves accessibility to chemical reaction sites in the particles of the active ingredient; specifically, this first facilitates the circulation of the electrolyte between the nanoparticles of the active ingredient and second facilitates the release of gases generated at these sites.

[0036] In terms of water electrolysis efficacy, excellent HHV efficiency was obtained when using a membrane comprising a catalyst layer in which the nanoparticles of the active component within the catalyst material layer comprise 65 to 85 wt% nickel nanoparticles and 15 to 35 wt% cobalt particles per 100 wt% of nanoparticles, more preferably 70 to 80 wt% nickel nanoparticles and 20 to 30 wt% cobalt particles. When using a membrane having a catalyst material layer on the cathode side comprising a mixture of nanoparticles of the active component containing 75 wt% nickel and 25 wt% cobalt, 1 A / cm² between the electrodes of the test cell 2 An efficiency of 80% HHV was obtained when a current density of 0.7 A / cm² was applied. 2 An efficiency of 85% HHV was obtained when a current density of was applied.

[0037] FIG. 5 shows the results of a test to evaluate the change in efficiency of a cell having a catalyst layer according to the present invention over time. The test was conducted at 30 cm 2 The test is performed using the test cell described above, comprising a membrane, a nickel cathode, and a stainless steel anode; the electrolyte used is potassium hydroxide KOH at a concentration of 4 mol / l; the membrane consists of yttria-stabilized zirconia with a PTFE binder, and its cathode side is covered with a catalyst layer. The test is performed at a temperature T = 90°C and 0.7 A / cm² 2 It was performed for a period of tens of hours at the applied current density.

[0038] The light gray curve shows the voltage change of a membrane containing a catalyst layer containing 40% active nanoparticles containing 60% carbon and 100% nickel on the cathode side.

[0039] The dark gray curve shows the voltage change of a membrane containing a catalyst layer containing 40% active nanoparticles containing 60% carbon, 80% nickel, and 20% cobalt on the cathode side.

[0040] At the start, during the first hour, the catalytic activity of the catalyst layer containing nickel alone is higher (lower voltage of approximately 1.85 V) than the catalytic activity of the catalyst layer containing nickel and cobalt (voltage of approximately 1.91 V).

[0041] Over time, the catalytic activity of the catalyst layer containing only nickel gradually increases: the voltage is observed to increase from about 1.88 V after about 10 hours to about 1.92 V after about 250 hours. Therefore, the efficiency gradually decreases over time.

[0042] Conversely, surprisingly, the catalytic activity of the catalyst layer containing nickel and cobalt gradually decreases and stabilizes: the voltage decreases from about 1.91 V at the start to 1.88 V after about 10 hours, further decreases to stabilize at a value of about 1.875 V, and this value is still maintained after about 250 hours. Thus, the combination of nickel and cobalt makes it possible to obtain superior efficiency and stable efficiency over time.

[0043] The efficiency of the membrane is particularly determined by the amount of nanoparticles present in the catalyst layer. The best efficiency is achieved when the catalytic material layer is 0.1 to 6 mg / cm² on the surface. 2 Nanoparticles of the active ingredient, more precisely, 1 cm 2 It was obtained in a membrane containing 0.1 to 7 mg of nanoparticles in a volume corresponding to the thickness of the catalyst layer multiplied by the membrane area.

[0044] The catalyst layer preferably has a thickness of 50 μm to 250 μm.

[0045] The efficiency of the membrane is also determined by the catalytic activity of the nanoparticles, which increases as the number of electrochemical reaction sites for the dissociation of water molecules increases. The chemical reaction sites are located on the surface of the catalytic material.

[0046] In order to increase the number of reaction sites on the particles of active ingredients such as nickel and cobalt, test results showed that increasing the specific surface area of ​​the catalytic material is an effective solution. To this end, in the context of the present invention, the nanoparticles of the active ingredient have a size of less than 50 nm, preferably less than 20 nm, and even more preferentially less than 5 nm. The particles have a general shape of substantially spherical or convex polyhedrons, and their size corresponds to their largest dimension.

[0047] Test results also showed that the catalytic activity of the particles is improved by improving the uniformity of particle size for a given particle size; this is the case when the particles contain a mixture of particles of the active ingredient, and even more so when the particles contain particles of the active ingredient and carbon particles.

[0048] Test results also showed that the uniformity of the mixture of active ingredient particles or the mixture of active ingredient particles and carbon particles (in terms of particle type) further improved catalytic activity.

[0049] The efficiency of the membrane is also determined by the excellent cohesion between the nanoparticles, the excellent cohesion between the catalyst layer and the main layer of the membrane, and the durability of this cohesion over time. Test results show that the polymer binder is an ionomer selected as a function of its ion conductivity characteristics as well as its resistance over time to corrosive chemical environments and high temperatures up to 120°C. The binder acts as an adhesive in the catalyst layer through polymerization and binds the particles and nanoparticles in this layer. This also allows for excellent adhesion between the catalyst layer and the membrane. Finally, an important point in the context of the present invention is that, because the ionomer is ionically conductive, it enables the catalyst layer to maintain electrical and ion conductivity. The ionomer preferred for use is known by the designation Nafion® and is derived by the polymerization of a monomer referred to as tetrafluoroethylene-perfluorosulfonic. The proportion of the polymer binder is 10% to 40% by weight of the binder / active ingredient particle mixture (or, where appropriate, the binder / active ingredient particle + carbon particle mixture).

[0050] The efficiency of the membrane is also determined by the method of preparing the catalyst layer on the main layer of the membrane.

[0051] To this end, the present invention proposes a method for depositing a catalyst layer on an anion-conductive membrane, wherein the catalyst layer comprises nanoparticles of at least two active components and a polymer binder, and the method comprises the step of preparing a liquid ink comprising nanoparticles and a polymer binder, wherein the nanoparticles comprise particles of at least two active components;

[0052] The step of manufacturing liquid ink is

[0053] - A step of mixing nanoparticles into a liquid, wherein the liquid is water, a solvent, or a mixture of water and a solvent, and the solvent is, for example, an alcohol.

[0054] - A step of grinding a mixture of particles in a liquid medium until a uniform mixture is obtained,

[0055] - Step of adding liquid polymer binder

[0056] Includes

[0057] In an example of a catalyst according to the present invention, the particles of the active component are nickel particles and cobalt particles.

[0058] The liquid is water, a solvent, or a mixture of water and a solvent. The solvent is suitable for diluting the binder. The solvent is, for example, alcohol. Tests that yielded satisfactory results were performed using, for example, water, ethanol, and a mixture of water and isopropanol.

[0059] The amount of selected liquid is suitable for wetting solid nanoparticles, facilitating the subsequent grinding step and limiting worker exposure to nanoparticle dust generated during the grinding step.

[0060] The amount of liquid is also selected so that the generated ink can be sprayed onto the film. In tests performed and satisfactory results obtained, an amount of liquid with a weight equivalent to 10 to 25 times the weight of the solid particles was used.

[0061] The grinding of nanoparticles is performed in an aqueous medium, for example, in a planetary mixer / mill (or ball mill). The grinding of a mixture of particles of at least two different components (which may also be referred to as co-grinding) makes it possible to obtain smaller nanoparticles of a selected size, less than 50 nm, preferably less than 20 nm, and even more preferentially less than 5 nm, and to obtain particles having the most uniform average size possible.

[0062] In the method according to the present invention, grinding makes it possible to obtain a ground material comprising particles containing atoms or molecules of a first active ingredient and particles containing atoms or molecules of a second active ingredient, and surprisingly, particles containing atoms or molecules of two (or more) different active ingredients. For example, grinding a mixture of nickel particles and cobalt particles makes it possible to obtain a ground material comprising nickel particles, cobalt particles, and Ni-Co alloy particles. Thus, grinding makes it possible to physically aggregate the particles together by physically pressing the particles against each other. The ground material thus obtained has higher catalytic activity than the mixture of particles before grinding.

[0063] Nanoparticle mixtures in liquid also make it possible to obtain a homogeneous mixture of materials (in terms of the distribution of various types of particles), particularly when two or more types of nanoparticles are used (e.g., nickel and cobalt here, or nickel, metal oxides and / or molybdenum or platinum, copper, zinc).

[0064] When carbon is used to support the nanoparticles of the active ingredient, the manufacturing step also, prior to the addition of the polymer binder,

[0065] - A step of adding carbon particles to the ground material of the nanoparticles of the active ingredient, and

[0066] - A step of grinding the mixture of active ingredient particles and carbon particles until a uniform mixture is obtained.

[0067] Includes

[0068] Carbon exists in the form of activated carbon or graphite, for example, having particles of about 0.2 to 0.9 μm.

[0069] This second grinding step enables the incorporation of nanoparticles of the active ingredient into carbon particles with a large specific surface area. This allows for the homogenization of the size of the carbon particles and the particles of the active ingredient, which also enables the proper distribution of the active ingredient particles within the center of the carbon particles and their adhesion to the carbon particles as effectively as possible. This step can also be performed using support materials other than carbon.

[0070] After adding a polymer binder, a mixing step is performed to obtain a uniform ink.

[0071] The manufacturing step described above makes it possible to obtain an ink containing catalyst nanoparticles in a suspended state, and said composition will also be referred to as "catalytic ink".

[0072] The catalyst ink prepared in this way is ultrasonically spray-coated onto the main layer of an anion-conductive membrane. The deposition of the catalyst ink by the ultrasonically spray-coating method, combined with the fluidity of the ink, enables the nanoparticles to be appropriately separated from each other to avoid aggregation during spraying. This method also makes it possible to maintain the ink uniformly throughout the spraying process. Furthermore, due to the pressure effect, this spraying method enables the ink to adhere excellently to the main layer of the membrane. As a result, a catalyst layer with a particularly uniform and even distribution of nanoparticles is produced; additionally, the obtained layer has a very thin thickness of about 50 μm to 250 μm in the case of a layer containing nickel, cobalt, and carbon on the cathode side, and is particularly uniform across the entire membrane surface. Finally, this method is 5 m depending on the composition of the catalyst ink. 2 / g to 200 m 2 It is possible to obtain a porous catalyst layer having a high specific surface area of ​​ / g (ratio between the active surface area and the weight of the catalyst layer).

[0073] After thorough drying, the film can be stored.

[0074] Drying enables the evaporation of a liquid, water, or a mixture of water and solvent. As a result, the catalyst layer deposited on the film contains only particles bound by a polymer binder.

[0075] The method according to the present invention can be performed to deposit a first catalyst layer on a first surface of the main layer of the membrane, and then optionally deposit a second catalyst layer on a second surface of the main layer of the membrane.

[0076] Accordingly, the method according to the present invention can be performed to manufacture an anion-conductive membrane (10) comprising a main layer covered by the following:

[0077] - A first catalytic material layer comprising nanoparticles of an active component bonded by a polymer binder, wherein the active component is nickel and cobalt,

[0078] - Or, a first catalytic material layer on one side of the main layer, and a second catalytic material layer on the other side of the main layer.

[0079] The second catalytic material comprises nanoparticles of an active component bonded by, for example, a polymer binder, and said active component is nickel, metal oxide and / or molybdenum.

[0080] FIG. 1 shows a drawing of a cell suitable for a water electrolysis unit for the production of gaseous hydrogen H2 and oxygen O2. The cell includes a cathode (20), an anode (30), and a membrane (30) between the two. FIG. 2 shows a schematic diagram of a water electrolysis unit including a cell according to the present invention. The membrane (10) divides the cell into two, said cell containing water and an electrolyte, in one example, a solution of potassium hydroxide KOH. The membrane is covered on one side by a catalytic material layer (40) containing nickel and cobalt nanoparticles supported by activated carbon and on the other side by a catalytic material layer (50) containing nickel and molybdenum nanoparticles. The cathode (20) and the anode (30) are positioned on both sides of the membrane and are connected to the negative and positive terminals of a power source, respectively. The membrane (10) allows for the effective separation of hydrogen gas produced at the cathode and oxygen gas produced at the anode. The cathode and anode may be metallic and, for example, may be made of nickel and stainless steel, respectively. When using the membrane having a zirconia-based main layer and two layers of catalytic material on both sides of the main layer, 1 A / cm between the electrodes of the cell 2 An efficiency of 84% HHV was obtained when a current density of 0.7 A / cm² was applied. 2 An efficiency of 90% HHV was obtained when a current density of was applied.

[0081] A single cell is shown in Fig. 1. However, in reality, an industrial unit may contain multiple cells, or even about 100 cells.

Claims

Claim 1 A catalyst material layer for an anion-conducting membrane (10) for an electrochemical device, wherein the catalyst material layer comprises nanoparticles of an active component bonded by a polymer binder, and the active component is nickel and cobalt. Claim 2 A catalyst material layer according to claim 2, wherein the active ingredient comprises 65 wt% to 85 wt% nickel and 15 wt% to 35 wt% cobalt, preferably 70 wt% to 80 wt% nickel and 20 wt% to 30 wt% cobalt, and more preferentially 75 wt% nickel and 25 wt% cobalt. Claim 3 A catalytic material layer according to claim 1 or 2, wherein the nanoparticles of the active ingredient are supported by carbon particles, and the nanoparticles of the active ingredient and the carbon particles are mixed and bonded by a polymer binder. Claim 4 In paragraph 3, a catalytic material layer in which carbon is in the form of activated carbon or graphite. Claim 5 In paragraph 3 or 4, the mixture of the active ingredient and carbon - 40% to 80% by weight of carbon, and - A catalytic material layer comprising 20% ​​to 60% by weight of an active ingredient. Claim 6 In paragraph 3 or 4, - 60% to 90% by weight of an active ingredient in particulate form or a mixture of the active ingredient and carbon, and - A catalytic material layer comprising 10% to 40% by weight of a binder. Claim 7 In any one of paragraphs 1 to 3, 0.1 to 6 mg / cm² on the surface 2 A catalytic material layer containing the active ingredient of. Claim 8 A catalytic material layer according to any one of claims 1 to 4, wherein the polymer binder is an ionomer, preferably a sulfonated tetrafluoroethylene-based fluoropolymer-copolymer (Nafion). Claim 9 A layer according to any one of claims 1 to 5, wherein the nanoparticles of the active ingredient and / or carbon nanoparticles have a size of less than 50 nm, preferably less than 20 nm, and more preferentially less than 5 nm. Claim 10 An anion-conducting membrane (10) for an electrochemical device, wherein the membrane comprises a main layer, and the main layer is covered by a catalytic material layer as claimed in any one of claims 1 to 9, or is covered on one side by a catalytic material layer as claimed in any one of claims 1 to 9 and on the other side by a second catalytic material layer. Claim 11 A method for depositing a catalyst layer on a main layer of an anion-conductive membrane, wherein the catalyst layer comprises nanoparticles of at least two active components and a polymer binder, and wherein the method comprises the step of preparing a liquid ink, wherein the step comprises the following steps: - A step of mixing nanoparticles of an active ingredient into a liquid, wherein the liquid is water, a solvent, or a mixture of water and a solvent, and the solvent is, for example, an alcohol. - A step of grinding a mixture of nanoparticles of the active ingredient and a liquid, - A step of adding a polymer binder to the ground material and mixing. Claim 12 A method according to claim 11, wherein the manufacturing step also comprises the following steps, performed before the addition of the polymer binder: - A step of adding carbon particles to the ground material of the nanoparticles of the active ingredient, and - A step of grinding the mixture of active ingredient particles and carbon particles until a uniform mixture is obtained. Claim 13 A method according to claim 8 or 9, further comprising the step of ultrasonically spray-coating the liquid ink onto the main layer of an anion-conductive membrane. Claim 14 A cell for an electrochemical device, comprising an anode (30), a cathode (20), and a membrane (10) between the anode and the cathode as claimed in claim 10. Claim 15 A water electrolysis unit comprising at least one cell as claimed in claim 14.

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