Component for a fuel cell

Abstract

The invention relates to a component for a fuel cell or an electrolyser, with an acid electrolyte, alkaline electrolyte, solid oxide electrolyte or molten salt electrolyte, provided with an anti-corrosion coating, and to such a fuel cell or electrolyser with an acid electrolyte, the component comprising an electrically non-conductive substrate (31) and an anti-corrosion coating (32) deposited on at least one surface of the substrate (31), the anti-corrosion coating (32) comprising at least one main layer based on tantalum nitride doped using one or more dopants selected from the family of transition metals and / or lanthanides.

Description

Fuel cell component Technical Field

[0001] This disclosure relates to a component for a fuel cell or electrolyser, with acid electrolyte, alkaline electrolyte or solid oxide or molten salt electrolyte, as well as such a fuel cell or electrolyser, with acid electrolyte, alkaline electrolyte or solid oxide or molten salt electrolyte.

[0002] Such a component, having an electrical conduction function, may in particular equip: a proton exchange membrane fuel cell, also designated by the acronym “PEMFC” for “Proton Exchange Membrane Fuel Cell” in English, a phosphoric acid fuel cell, also designated by the acronym “PAFC” for “Phosphoric Acid Fuel Cell” in English, a direct methanol fuel cell, also designated by the acronym “DMFC” for “Direct Methanol Fuel Cell” in English, a direct ethanol fuel cell, also designated by the acronym “DEFC” for “Direct Ethanol Fuel Cell” in English, or a direct ethylene glycol fuel cell, also designated by the acronym “DEGFC” for “Direct Ethylen Glycol Fuel Cell” in English. Prior art

[0003] Conductive components, such as terminal plates, bipolar plates and interconnectors, used in fuel cells are exposed to both oxidizing conditions, due in particular to the presence of oxygen and / or water, and corrosive conditions, due in particular to acid effluents from the electrolyte, which are extremely harsh and lead, in the absence of adequate protection, to rapid deterioration leading to a loss of conductivity of these components as well as to pollution of the environment of the fuel cell, in particular its electrolyte and / or its catalysts, by the products resulting from this corrosion.

[0004] In particular, alkaline electrolyte fuel cells are exposed to harsh alkaline corrosion conditions due in particular to alkaline effluents from the electrolyte.

[0005] This is all the more critical in a solid oxide electrolyte fuel cell because the operating temperature of such a cell is between 500 and 1000°C, which significantly promotes corrosion processes.

[0006] These corrosion conditions are also particularly severe in a fuel cell or molten salt electrolyser due, on the one hand, to the high operating temperature, generally around 650°C, and, on the other hand, to the presence of molten salts from the electrolyte.

[0007] To limit this corrosion, one option is to use very specific alloys that naturally have high corrosion resistance. This could include Inconel 625. However, such special alloys are expensive. In addition, their natural corrosion resistance may be insufficient in certain applications.

[0008] A second option is to use more conventional materials for such conductive components but to protect them with an anti-corrosion coating. Many materials have been tested in the scientific literature, including graphite or conductive metal oxide coatings.

[0009] However, in addition to very good corrosion protection properties, this anti-corrosion coating must have good stability and sufficient electrical conductivity so as not to hinder the electrical operation of the fuel cell. In particular, the conductivity of the coating must remain above 100 S / cm. In addition, the coating must be sufficiently thin, for example less than 5 μm, so as not to modify the geometry of the component, especially when the latter includes channels.

[0010] However, to date, both in the field of proton exchange membrane fuel cells (PEMFC) and in that of phosphoric acid fuel cells (PAFC), or in the field of alkaline fuel cells AFC, or direct urea fuel cells DUFC, or in the field of solid oxide fuel cells SOFC, protonic ceramic fuel cells PCFC or direct carbon fuel cells DCFC, the only known solution allowing to achieve a lifetime greater than 5000 h and an acceptable degradation rate, i.e. less than 40 pV / h, is the pure gold coating, with a thickness of 200 to 500 nm.

[0011] This is also the case in the field of direct methanol fuel cells (DMFC), direct ethanol fuel cells (DEFC) or direct ethylene glycol fuel cells (DEGFC) or in the field of molten salt electrolyte fuel cells.

[0012] However, such a pure gold coating significantly increases the cost of the fuel cell. Thus, when all the conductive components of the fuel cell are equipped with such a coating, the cost of this coating alone can represent up to half of the total cost of the fuel cell.

[0013] Additionally, even pure gold coatings eventually wear off, contaminating the fuel cell environment. In particular, gold particles can deposit on certain fuel cell components and create electrical connections in unwanted locations, reducing the fuel cell's efficiency.

[0014] There is therefore a real need for a component for a fuel cell or electrolyser, with acid electrolyte, alkaline electrolyte or solid oxide electrolyte or molten salt, as well as for a fuel cell or an electrolyser, with acid electrolyte, alkaline electrolyte or solid oxide electrolyte or molten salt, comprising such a component, which are free, at least in part, from the drawbacks inherent in the aforementioned known configurations. Statement of the invention

[0015] The present disclosure relates to a component for a fuel cell or electrolyser, with acid electrolyte, alkaline electrolyte or solid oxide electrolyte or molten salt, comprising a substrate, electrically non-conductive, and an anti-corrosion coating deposited on at least one surface of the substrate, in which the anti-corrosion coating comprises at least one main layer based on tantalum nitride doped with one or more doping elements chosen from the family of transition metals and / or lanthanides.

[0016] As will be explained below in the detailed description, such a layer of tantalum nitride doped in this way offers very good protection against corrosion while benefiting from good electrical conductivity. In particular, the inclusion of one or more dopants makes it possible to increase the stability chemical reaction of tantalum nitride, usually metastable, forming solid solutions.

[0017] This provides very good resistance to acid corrosion in oxidizing and reducing environments respectively, in a temperature range from 0°C to 300°C.

[0018] In particular, very good resistance to oxidation due to the oxidant, O2 or air, as well as to corrosion caused by alkaline effluents from the membrane and the presence of liquid water generated by the cell is obtained.

[0019] Very good resistance to high-temperature corrosion, particularly caused by molten salts in the case of a molten salt fuel cell, as well as to carbonation, is also achieved.

[0020] The component thus obtained is therefore capable of ensuring its current conduction function efficiently and sustainably, despite the highly oxidizing conditions prevailing in the fuel cell or the electrolyser.

[0021] In particular, thanks to the high stability of doped tantalum nitride, the coating practically does not degrade over time: this reduces the risk, on the one hand, of seeing the conductivity of the component decrease over time and, on the other hand, of polluting the environment of the fuel cell or electrolyser, in particular its electrolyte or its catalysts, and therefore of reducing its efficiency. Thus, such a coating makes it possible to achieve an extremely long service life for the component, of the order of 20,000 to 30,000 hours.

[0022] Furthermore, the cost of obtaining a doped tantalum nitride coating is significantly lower than that of a pure gold coating, which significantly reduces the overall cost of the fuel cell or electrolyzer.

[0023] Tantalum nitride also has the advantage of remaining stable up to around 3000°C, which allows its use in a very wide range of applications, including at very high temperatures.

[0024] Furthermore, thanks to the high electrical conductivity of this anti-corrosion coating, it is possible to replace the usual conductive substrate with a non-conductive substrate while maintaining the electrical conduction function of the component, the electrical conduction being ensured by the anti-corrosion coating itself and no longer by the substrate.

[0025] This opens up a much wider range of possible materials, which makes it possible to choose less expensive and / or less dense materials, and therefore more lightweight, without the need to add conductive fillers. This also makes it possible to choose materials that are easy to shape.

[0026] In some embodiments, the component is a component for a fuel cell or electrolyzer with acid electrolyte and gaseous fuel.

[0027] In other embodiments, the component is a component for a fuel cell or electrolyzer with acid electrolyte and liquid fuel.

[0028] In some embodiments, the substrate is made of polymeric material, in particular thermoplastic and / or elastomer.

[0029] This reduces the cost and mass of the component compared to a conventional metal substrate.

[0030] In some embodiments, the substrate is made of an organic matrix composite material. Such materials are lightweight while providing good mechanical strength.

[0031] In some embodiments, the main layer is made essentially of tantalum nitride doped with one or more doping elements selected from the family of transition metals and / or lanthanides. The main layer is thus essentially uniform.

[0032] In some embodiments, the main layer is two-phase or multi-phase. In particular, the main layer may have a compositional gradient, for example in the direction perpendicular to the substrate.

[0033] In some embodiments, the primary layer is made essentially of tantalum nitride.

[0034] On the other hand, the main layer may exhibit a compositional variation affecting the crystalline structure and / or the doping of the tantalum nitride. In particular, a gradient in crystalline structure has the advantage of improving the accommodation of stresses between the coating and its substrate, which improves the mechanical properties of the complete system, by limiting cracks and / or delamination of the coating.

[0035] In some embodiments, the electrolyte of the fuel cell or electrolyzer is a proton exchange membrane.

[0036] In some embodiments, the electrolyte of the fuel cell or electrolyzer is phosphoric acid.

[0037] In some embodiments, the component has an electrical conduction function within the fuel cell or electrolyzer.

[0038] In particular, the component can be a terminal plate, a bipolar plate or even an interconnector for a fuel cell or electrolyzer.

[0039] In some embodiments, the crystal system of the tantalum nitride in the main layer is hexagonal. Indeed, in addition to excellent corrosion resistance, hexagonal tantalum nitride benefits from conductivity almost as good as that of gold.

[0040] In some embodiments, the crystal system of the tantalum nitride in the main layer is cubic. Indeed, although slightly less conductive than hexagonal tantalum nitride, cubic tantalum nitride also benefits from excellent corrosion resistance, particularly when doped as is the case here.

[0041] In some embodiments, the total dopant content within the main layer is between 1 ppm and 10 at%, in particular between 10 ppm and 1 at%, in particular between 0.2 and 0.5 at%.

[0042] In some embodiments, the primary doping element is selected from zirconium, hafnium, nickel, vanadium, titanium, niobium, chromium and / or molybdenum.

[0043] In some embodiments, the doping element used, preferably only one, is vanadium (V).

[0044] Indeed, vanadium very easily forms a solid solution with tantalum nitride, which increases its stability. In addition, vanadium is difficult to oxidize: consequently, even if a small fraction of vanadium is released into the fuel cell or electrolyzer environment, its impact on the electrolyte or catalysts will be very low.

[0045] In some embodiments, the doping element used, preferably only one, is nickel (Ni). This dopant is particularly preferred for acid electrolyte and liquid fuel fuel cells.

[0046] Indeed, in most acid electrolyte and liquid fuel fuel cells, nickel is already present in at least one of the catalysts. Thus, even if a small fraction of the nickel in the coating is released into the fuel cell environment, its impact will be reduced since it will not affect the catalysts already containing nickel.

[0047] In some embodiments, the content of the main dopant within the main layer is between 1 ppm and 10 at%, in particular between 10 ppm and 1 at%, in particular between 0.2 and 0.5 at%.

[0048] In some embodiments, the thickness of the anti-corrosion coating is between 5 nm and 5 μm, in particular between 10 nm and 1 μm, in particular between 100 nm and 300 nm.

[0049] In some embodiments, the anti-corrosion coating comprises several superimposed layers, in particular between 2 and 10 layers.

[0050] The material of the primary layer constitutes a primary material, and the anti-corrosion coating comprises at least one secondary layer based on a secondary material different from the primary material.

[0051] Such a multi-layer structure helps to increase the mechanical strength of the coating, with each interface between two separate layers helping to deflect any cracks that may appear in the material. As a result, it is possible to reduce the risk of a crack propagating to the substrate, thus allowing the substrate to remain protected against corrosion.

[0052] In some embodiments, the anti-corrosion coating comprises at least three layers each comprising a different material.

[0053] In some embodiments, each layer of the coating comprises a thickness of between 1 and 500 nm, in particular between 10 and 100 nm.

[0054] In some embodiments, the topmost layer of the anti-corrosion coating is a primary layer made of the primary material. The first line of protection is thus provided by the primary material, which is generally the one with the best anti-corrosion properties. However, in other embodiments, the topmost layer of the anti-corrosion coating could be a secondary layer.

[0055] In some embodiments, the main material constitutes at least 30% by volume, in particular at least 50% by volume, of the anti-corrosion coating. This ensures, overall, particularly high anti-corrosion protection.

[0056] In some embodiments, the anti-corrosion coating comprises alternating layers of the primary material and the secondary material. Such alternation is particularly effective in stopping cracks before they reach the substrate.

[0057] In some embodiments, the secondary material is crystallographic tantalum nitride having a different crystal system and / or doping than the primary material.

[0058] In particular, the secondary material may comprise one or more different doping elements, or it may be undoped. In this way, the secondary material has anti-corrosion properties that remain very high, which makes it possible to ensure satisfactory anti-corrosion protection even in the event of cracking of the main layer.

[0059] In some embodiments, the secondary layer consists essentially of the secondary material.

[0060] In some embodiments, the secondary layer is two-phase or multi-phase.

[0061] In particular, the secondary layer may have a composition gradient, for example in the direction perpendicular to the substrate.

[0062] In some embodiments, the secondary layer is made essentially of tantalum nitride.

[0063] On the other hand, the secondary layer may present a variation in composition affecting the crystalline structure and / or the doping of the tantalum nitride.

[0064] In particular, layers with a gradient of crystalline structure have the advantage of improving the accommodation of stresses between a given layer and the lower layer, which improves the mechanical properties of the complete system, by limiting cracks and / or delamination of the coating at the interfaces. The doping gradient can similarly allow two successive layers to be better accommodated, avoiding a sudden change in composition that could generate a more mechanically fragile interface.

[0065] In some embodiments, the main layer is deposited using a co-sputtering process. The co-sputtering process may notably combine high-power pulsed magnetron sputtering, also referred to by the acronym “HiPIMS” for “High-Power Impulse Magnetron Sputtering” in English, using a tantalum target and magnetron sputtering using a target comprising the doping element.

[0066] Examples of high-power pulsed magnetron sputtering processes are described in particular in document FR 3 097 237.

[0067] The present disclosure also relates to a fuel cell or an electrolyzer, with acid electrolyte, comprising at least one component according to any one of the preceding embodiments.

[0068] In some embodiments, the fuel cell is of the electrolyte and gaseous fuel type.

[0069] In some embodiments, the fuel cell is of the PEMFC proton exchange membrane fuel cell type.

[0070] In some embodiments, the fuel cell is of the PAFC phosphoric acid fuel cell type.

[0071] In some embodiments, the fuel cell is configured to be supplied with hydrogen H2.

[0072] In some embodiments, the fuel cell is of the electrolyte and liquid fuel type.

[0073] In some embodiments, the fuel cell is of the direct methanol fuel cell DMFC type.

[0074] In some embodiments, the fuel cell is of the direct ethanol fuel cell (DEFC) type.

[0075] In some embodiments, the fuel cell is of the direct ethylene glycol fuel cell (DEGFC) type.

[0076] In some embodiments, the fuel cell is configured to be fueled with methanol CH3OH, ethanol C2H5OH, or ethylene glycol HOC2H4OH.

[0077] In some embodiments, the electrolyte of the fuel cell or electrolyzer is a solution of potassium hydroxide KOH and / or sodium hydroxide NaOH.

[0078] In some embodiments, the fuel cell is of the alkaline fuel cell (AFC) type.

[0079] In some embodiments, the fuel cell is of the metal / air cell type. It may in particular be a Zn / Air cell, an Al / Air cell, a Mg / Air cell or a Li / Air cell.

[0080] In some embodiments, the fuel cell is of the direct urea fuel cell (DUFC) type.

[0081] In some embodiments, the fuel cell is of the type supplied with gaseous fuel, preferably dihydrogen H2.

[0082] In some embodiments, the fuel cell is configured to be supplied with urea CO(NH2)2.

[0083] In some embodiments, the electrolyte of the fuel cell or electrolyzer is a ceramic, preferably yttria-stabilized zirconia, also referred to by the acronym "YSZ" for "Yttria-stabilized zirconia" in English.

[0084] In some embodiments, the electrolyte of the fuel cell or electrolyzer comprises one or more molten salts, preferably sodium carbonate NaCO3, potassium carbonate K2CO3 and / or lithium carbonate Li2CO3.

[0085] In some embodiments, the electrolyte of the fuel cell or electrolyzer comprises a porous matrix of oxide, preferably lithium aluminum oxide.

[0086] In some embodiments, the doping element used, preferably only one, is yttrium (Y). This dopant is particularly preferred for solid oxide electrolyte fuel cells.

[0087] In fact, in most solid oxide electrolyte fuel cells, the electrolyte already contains yttrium. Therefore, even if a small fraction of the yttrium in the coating is released into the fuel cell environment, its impact will be reduced since it will not affect the electrolyte.

[0088] In some embodiments, the doping element used, preferably only one, is chromium (Cr). This dopant is particularly preferred for fuel cells with molten salt electrolyte.

[0089] Indeed, given the critical oxidizing conditions prevailing in a fuel cell or an electrolyzer with molten salt electrolyte(s), minimal oxidation of the coating is practically inevitable, regardless of the resistance properties of the coating. Therefore, the choice of an element with good electrical conduction such as chromium makes it possible to maintain a good level of conduction within the fuel cell or the electrolyzer, even in the event of pollution by this doping element.

[0090] The present disclosure also relates to a fuel cell or an electrolyzer, with solid oxide electrolyte or molten salt, comprising at least one component according to any one of the preceding embodiments.

[0091] In some embodiments, the fuel cell is of the solid oxide fuel cell (SOFC) type.

[0092] In some embodiments, the fuel cell is of the PCFC protonic ceramic fuel cell type.

[0093] In some embodiments, the fuel cell is of the direct carbon fuel cell (DCFC) type.

[0094] In some embodiments, the fuel cell is of the molten carbonate fuel cell (MCFC) type.

[0095] In some embodiments, the electrolyzer is of the MCEC molten carbonate electrolyzer type.

[0096] In some embodiments, the fuel cell is of the direct urea fuel cell (DUFC) type.

[0097] In some embodiments, the fuel cell is configured to be supplied with gaseous fuel.

[0098] In some embodiments, the fuel cell is configured to be supplied with dihydrogen H2, ammonia NH3, or methane CH4.

[0099] In some embodiments, the fuel cell is configured to be fueled with a carbon-rich fuel C, preferably coal-based or biomass-based.

[0100] In some embodiments, the fuel cell is configured to be supplied with urea CO(NH2)2.

[0101] In this presentation, a part or part of a part is considered to be made from a given material when this material represents the majority material, by mass, in the composition of the part or part of the part.

[0102] In the present disclosure, it is considered that a part or part of a part is made essentially of a given material when it is formed at least 80%, preferably 90%, more preferably 99%, by this material.

[0103] The above-mentioned features and advantages, as well as others, will become apparent upon reading the following detailed description of examples of embodiments of the proposed component and fuel cell. This detailed description refers to the attached drawings. Brief description of the drawings

[0104] The attached figures are schematic and are intended primarily to illustrate the principles of the disclosure. In the figures, identical elements or parts of elements are identified by the same reference signs. In addition, elements or parts of elements belonging to different embodiments but having a similar function are identified in the figures by numerical references incremented by 100, 200, etc.

[0105] This description will be better understood and other characteristics and advantages will become apparent upon reading the detailed description which follows, comprising embodiments given for illustrative purposes with reference to the appended figures, presented as non-limiting examples, which may serve to supplement the understanding of this description and, where appropriate, contribute to its definition, in which:

[0106] [Fig. 1] Figure 1 is a schematic view of a fuel cell according to the disclosure;

[0107] [Fig. 2] Figure 2 is a schematic view of a cell of the fuel cell of Figure 1;

[0108] [Fig. 3] Figure 3 is a schematic view of a first example of a component according to the disclosure;

[0109] [Fig. 4] Figure 4 schematically illustrates a device allowing the production of a coating according to the description;

[0110] [Fig. 5] Figure 5 is a graph illustrating corrosion test results for the first example component according to the disclosure;

[0111] [Fig. 6] Figure 6 illustrates, in section and from the front, a microstructure of a cubic TaN coating deposited by a high-power pulsed magnetron sputtering process;

[0112] [Fig. 7] Figure 7 is a graph illustrating the results of corrosion tests for a second example component according to the disclosure;

[0113] [Fig. 8] Figure 8 is a schematic view of a third example component;

[0114] [Fig. 9] Figure 9 is a graph illustrating corrosion test results in the third example according to the disclosure;

[0115] [Fig. 10] Figure 10 illustrates, in section and from the front, a microstructure of a hexagonal TaN coating deposited by a high-power pulsed magnetron sputtering process;

[0116] [Fig. 11] Figure 11 illustrates, in section and from the front, a microstructure of a hexagonal TaN coating deposited by a conventional magnetron sputtering process; and

[0117] [Fig. 12] Figure 12 is a schematic of a cell of another example of a fuel cell;

[0118] [Fig. 13] Figure 13 is a schematic view of another example fuel cell;

[0119] [Fig. 14] Figure 14 is a schematic view of another example fuel cell;

[0120] [Fig. 15] Figure 15 is a schematic of a cell of another example of a fuel cell. Description of the embodiments

[0121] In order to make the present disclosure more concrete, examples of components and fuel cells are described in detail below, with reference to the accompanying drawings. It is recalled that the invention is not limited to such examples.

[0122] Figure 1 schematically illustrates a fuel cell 1 according to the invention. Such a fuel cell 1 comprises two end plates 11, 12 between which cells 20 are stacked in a stacking direction X.

[0123] Each cell 20 comprises, in an order defined from left to right in FIG. 1, a first bipolar plate 21, a first diffusion layer 22, a first electrode 23, an electrolyte 24, a second electrode 25, a second diffusion layer 26 and a second bipolar plate 27.

[0124] The bipolar plates 21, 27 have the function of distributing the reactants and, where appropriate, the heat transfer fluid which cools the cell when said cell has reached its nominal operating speed: the bipolar plates 21, 27 are thus provided with a network of channels 21a, 27a on each of their faces. The bipolar plates 21, 27 also have the function of conducting an electric current between the successive cells 20. Thus, each bipolar plate 21, 27 is located at the interface between two successive cells 20, the second bipolar plate 27 of the N e cell 20 constituting the first bipolar plate 21 of the (N+1) e cell 20, thus electrically connecting in series the N e and (N+1) e 20 cells.

[0125] The end plates 11, 12 play the same role as the bipolar plates 21, 27 except that they are provided at the ends of the stack, thus closing respectively the left side of the first cell 20 and the right side of the last cell 20: the terminal plates 11, 12 therefore only have a network of channels 11a, 12a on one of their faces. Also conductive, they constitute the terminals of the fuel cell as a whole: thus, the terminals of the electrical load 2 to be supplied, for example a motor, can be connected to each of the terminal plates 11, 12.

[0126] The diffusion layers 22, 26 have the function of allowing the diffusion of the reactants from the bipolar plate 21, 27 towards the electrode 23, 25 concerned, and of the reaction products, from this same electrode 23, 25 towards the bipolar plate 21, 27. This diffusion can in particular be made possible by grooves or a network of porosities for example.

[0127] The electrodes 23, 25 are the seat of the electrochemical half-reactions ensuring the operation of the fuel cell 1: the first electrode 23 thus forms the anode while the second electrode 25 forms the cathode. The electrodes 23, 25 are porous, preferably microporous, in order to allow access to the reactants and the evacuation of the reaction products. The first electrode 23 and / or the second electrode 25 is provided with a catalyst making it possible to catalyze the electrochemical half-reaction in question.

[0128] The electrolyte 24 has the function of allowing the migration of certain ions between the anode 23 and the cathode 25 while preventing the passage of electrons resulting from the oxidation half-reaction at the anode 23. The electrons e- thus formed are then conducted to the cathode 25 of the immediately preceding cell 20 where they are consumed by the reduction half-reaction. The electrons formed by the first cell 20 are for their part collected by the first terminal plate 11, supply the load 2, and join the cathode 25 of the last cell 20 via the second terminal plate 12.

[0129] Figure 2 illustrates more precisely the operation of a cell 20 in the context of a first exemplary embodiment. In this first example, the fuel cell 1 is a proton exchange membrane fuel cell (PEMFC).

[0130] In such a fuel cell 1, the fuel supplied to the anode 23 is dihydrogen H2 while air is supplied to the cathode 25.

[0131] Electrolyte 24 consists of a proton exchange membrane capable of allowing H protons to pass through + while retaining the electrons e-. The The proton exchange membrane also prevents the passage of any gases. Platinum is used as a catalyst at both the anode 23 and cathode 25.

[0132] Anode 23 is thus the seat of the following oxidation half-reaction: H22H + + 2nd-

[0133] Cathode 25 is the seat of the following reduction half-reaction: 4H + + 4e- + O22H2O

[0134] So, overall, the operating equation of fuel cell 1 is as follows: 2H2+ O22H2O

[0135] In such a proton exchange membrane cell, the membrane 24 acts as an acid electrolyte. It can be a membrane based on Nafion (registered trademark), i.e. a fluoropolymer copolymer based on sulfonated tetrafluoroethylene, or a membrane based on polybenzimidazole doped with phosphoric acid.

[0136] Due to this highly corrosive environment, the end plates 11, 12 and the bipolar plates 21, 27 must be able to resist corrosion while continuing to perform their electrical conduction function.

[0137] Figure 3 then schematically represents such a component, designated by the generic reference 30, according to the first exemplary embodiment.

[0138] The component 30 thus comprises a non-conductive substrate 31, made for example from an organic matrix composite, and an anti-corrosion coating 32 deposited on the substrate 31, the anti-corrosion coating 32 having a thickness eï of 380nm.

[0139] In this first example, the anti-corrosion coating 32 comprises a single layer made of tantalum nitride TaN doped with zirconium Zr. This compound, of formula Tai. x Zr x N (with 0 < X ​​< 1), has a stable crystal structure in which zirconium atoms substitute for tantalum Ta atoms, thus forming a solid solution.

[0140] In this example, the crystal system of this compound is cubic, more precisely a face-centered cubic lattice. However, this compound is also capable of crystallizing in a hexagonal form, which is also quite suitable.

[0141] In this example, zirconium is present at 5.8 + / - 0.6 at% within this compound.

[0142] Such an anti-corrosion coating 32 can be deposited on the substrate 31 using the device 50 shown schematically in FIG. 4. This device 50 makes it possible to carry out co-sputtering by high-power pulsed magnetron cathode sputtering.

[0143] The device 50 comprises a chamber 51 intended to receive a plasma gas, for example consisting of a mixture of argon and nitrogen. The device further comprises a source of plasma gas (not shown) in communication with the chamber 51. The pressure in the chamber 51 is set between 0.1 and 20 Pa. The gas mixture comprises between 5 and 90% at nitrogen. In the present example, the pressure is set at 0.15 Pa and the gas mixture of argon and nitrogen comprises 10% nitrogen.

[0144] The chamber 51 comprises a tantalum target 52, constituting a first cathode, and a zirconium target 53, constituting a second cathode. The two targets 52 and 53 are arranged on the same side of the chamber 51, forming an angle of 90° with respect to each other.

[0145] The substrate 31 to be covered, constituting the anode, is arranged within the chamber 51 opposite the targets 52, 53, perpendicularly and centered relative to the bisector of the two targets 52, 53.

[0146] In the present example, the first target 52 comprises tantalum in an amount of more than 99% in atomic percentages, and preferably in an amount of more than 99.9% in atomic percentages. The second target 53 comprises zirconium in an amount of more than 99% in atomic percentages, and preferably in an amount of more than 99.9% in atomic percentages.

[0147] During the deposition of the coating 32, the tantalum target 52 is polarized using a pulsed polarization, to which a continuous polarization is optionally superimposed. The polarization of the first target 52 is imposed by a first electrical power supply device 54 comprising a voltage pulse generator electrically connected to the tantalum target 52.

[0148] The voltage pulse generator makes it possible to impose the pulsed polarization on the tantalum target 52. Such a configuration is notably described in document FR 3 097 237.

[0149] The pulse width can be between 1 ps and 900 ps. The pulse frequency can be between 50 Hz and 5000 Hz. The pulse voltage can be between -100 V and -1500 V.

[0150] In this example, the pulse width is 30 ps, ​​the pulse frequency is 1000 Hz, and the pulse voltage is -1000 V.

[0151] Similarly, the zirconium target 53 is polarized using a second electrical power supply device 55 configured to provide radio-frequency polarization, of the order of 13.6 MHz, with a power of between 10 W and 1000 W.

[0152] However, in other examples, the second power supply device 55 could be configured to provide a continuous bias, with a voltage between -100 V and -1500 V, and / or a pulsed bias, with a pulse width between 1 ps and 900 ps, ​​a pulse frequency between 50 Hz and 5000 Hz and a pulse voltage between -100 V and -1500 V.

[0153] In the chamber 51, the application of a voltage between the target 52 and the substrate 31 in the presence of an atmosphere comprising nitrogen makes it possible to create a plasma. Electrons are generated by the target 52 and can ionize by collision the atoms constituting the plasma. It is possible to introduce into the chamber 51 near the target 52 one or more permanent magnets, not shown, whose magnetic field confines the electrons generated near the target 51 and increases the probability that the collision between an electron and an atom of the plasma takes place there. When such a collision takes place, a high-energy species is generated, and the latter can bombard the target 52 and tear off, by elastic impact, particles from the target 52. The particles of the target 52 thus torn off can then be deposited on the substrate 31 to form the coating 32.

[0154] Similarly and simultaneously, particles of the target 53 are also torn from the target 53 and sprayed onto the substrate 31. It is possible to adjust the quantity of doping particles, here zirconium, in the coating 32 by adjusting the electrical power supplied to the second target 53. For example, in the present example, a power of 5W is applied to the zirconium target 53.

[0155] Specifically in this method, the substrate 31 is not heated during the deposition of the coating 32.

[0156] On the other hand, the pulse voltage, the pulse width and the pulse frequency of the polarization of the tantalum target 52 are adjusted, so that the energy difference between the incident electrons, of the order of a few eV where 1 eV = 11600 K, and the substrate 31 makes it possible to achieve ultra-quenching conditions, that is to say a cooling of the order of 106 K / s to 108 K / s, when the particles present in the plasma reach the substrate 31.

[0157] By adjusting the pulse parameters in this way, it is possible to obtain an energy distribution of the electrons in the discharge allowing a cooling speed adapted to the contact of the incident particles on the substrate 31.

[0158] This makes it possible to freeze the metastable configuration of the deposited coating 32 and therefore to freeze the targeted crystallinity, without it being necessary to heat the substrate 31.

[0159] In addition, the substrate 31 may be polarized during deposition. For this purpose, the substrate 31 may be polarized using a continuous polarization, with a voltage between 1 V and 1500 V, and / or a pulsed polarization, with a pulse width between 1 ps and 900 ps, ​​a pulse frequency between 10 Hz and 5000 Hz and a pulse voltage between 1 V and 1500 V. In particular, a pulsed polarization promotes the evacuation of a portion of the charges from the non-conductive substrate by recombination with the plasma. Such an effect fades as the coating is deposited, the coating being electrically conductive.

[0160] Figure 5 now illustrates corrosion test results for the coating 32 used in this first embodiment. This cyclic voltammetry test was carried out in the laboratory, at room temperature, by immersing a working electrode made of the material to be tested and a platinum counter-electrode in a 0.5 mol / L phosphoric acid bath, varying the potential applied to the working electrode relative to the counter-electrode and recording its current response.

[0161] Curve 61 then corresponds to a working electrode in 316L stainless steel, constituting a reference material.

[0162] Curve 62 corresponds to a working electrode made of 316L stainless steel completely covered with a coating of cubic tantalum nitride doped at 5.8 + / - 0.6% at with zirconium Zr, i.e. a coating 32 according to the first embodiment.

[0163] Curve 63 corresponds to a working electrode made of 316L stainless steel completely covered with a coating of cubic tantalum nitride doped at 6.0 + / - 0.4% at with zirconium Zr, i.e. a coating 32 according to an alternative embodiment.

[0164] As can be seen in Figure 5, curves 62 and 63, corresponding to the anti-corrosion coatings 32 according to the first embodiment and its variant, have significantly wider stability levels than curve 61 corresponding to the uncoated reference material 31, thus confirming the protection of the uncoated reference material 31 by the anti-corrosion coating 32.

[0165] This test also allows the corrosion potential and current to be measured for these different samples: [Table 1]

[0166] Thus, the corrosion current l corr of the anti-corrosion coatings 32 according to the present embodiment and its variant is more than 30% lower than that of the comparative sample of the uncoated reference material 31, thus confirming the excellent anti-corrosion properties of these coatings.

[0167] Furthermore, Figure 6 illustrates the microstructure of a cubic tantalum nitride coating, in cross-section and from the face, deposited by a high-power pulsed magnetron sputtering process according to the present example. The scale shown at the bottom of each view corresponds to 1 pm.

[0168] As can be seen in these two views, the microstructure of the coating is fine and homogeneous, which implies good mechanical resistance with, in particular, good resistance to the propagation of cracks within the coating.

[0169] For comparison, such a coating deposited by a conventional magnetron sputtering process results in an easily fracturable columnar microstructure.

[0170] It is also important to note that the anti-corrosion coatings 32 according to the first embodiment and its variant benefit from a conductivity well above 100 S / cm, which ensures sufficient conductivity for conduct electrons satisfactorily within the fuel cell or electrolyser, even when the substrate itself is non-conductive. Indeed, at 160°C, the conductivity of cubic tantalum nitride deposited by high-power pulsed magnetron sputtering is equal to 538 S / cm.

[0171] In this first example, the tantalum nitride TaN forming the anti-corrosion coating 32 is doped with zirconium.

[0172] However, in other examples, other doping elements, from transition metals or lanthanides, could be used instead of or in addition to zirconium.

[0173] In particular, in a second exemplary embodiment, the anti-corrosion coating comprises a single layer made of tantalum nitride TaN doped with hafnium Hf. This compound, of formula Ta^xHTN, has a stable crystalline structure in which the zirconium atoms replace tantalum atoms, thus forming a solid solution.

[0174] In this second example, the crystal system of this compound is also cubic, more precisely having a face-centered cubic lattice. However, this compound is also capable of crystallizing in a hexagonal form, which is also quite suitable.

[0175] In this second example, hafnium is present at 5.7 + / - 0.5% at within this compound.

[0176] A process completely analogous to that of the first example can be used to deposit this anti-corrosion coating on the substrate, by replacing the zirconium 53 target with a hafnium target.

[0177] Similar to Figure 5, Figure 7 illustrates corrosion test results for this second embodiment. This cyclic voltammetry test was carried out under the same conditions as the test carried out for the first embodiment.

[0178] Curve 161 then corresponds to a working electrode in 316L stainless steel, constituting a reference material.

[0179] Curve 162 corresponds to a working electrode made of 316L stainless steel completely covered with a coating of cubic tantalum nitride doped at 5.7 + / - 0.7% at with hafnium Hf, i.e. a coating according to the second embodiment.

[0180] Curve 163 corresponds to a working electrode made of 316L stainless steel completely covered with a coating of cubic tantalum nitride doped at 5.3 + / - 0.5% at with hafnium Hf, i.e. a coating according to an alternative embodiment of the second example.

[0181] As can be seen in Figure 7, curves 162 and 163, corresponding to the anti-corrosion coatings according to the second embodiment and its variant, have significantly wider stability levels than curve 161 corresponding to the uncoated reference material, thus confirming the protection of the reference material by the anti-corrosion coating.

[0182] This test also allows the corrosion potential and current to be measured for these different samples: [Table 2]

[0183] Thus, the corrosion current l corr anti-corrosion coatings according to the second embodiment example and its variant is more than 10% lower than that of the comparative sample of the uncoated reference material, thus confirming the excellent anti-corrosion properties of these coatings.

[0184] Figure 8 schematically represents a component 230 according to a third exemplary embodiment. Again, the component 230 comprises a non-conductive substrate 231, made for example from an organic matrix composite, and an anti-corrosion coating 232 deposited on the substrate 231.

[0185] In this third example, the anti-corrosion coating 232 comprises a plurality of superimposed layers 233, more precisely ten layers in the present example, each having a thickness e n of 50 nm for a total coating thickness e t of 500 nm.

[0186] In this third example, the anti-corrosion coating 232 comprises two types of layers 233 deposited alternately: main layers 233a, made of a main material, and secondary layers 233b, made of a secondary material. Here, the uppermost layer of the anti-corrosion coating 232, exposed to the environment, is a main layer 233a.

[0187] In this third example, the main material, i.e. the material of the main layers 233a, is cubic tantalum nitride TaN doped with zirconium Zr. In particular, this main material may correspond to the material of the anti-corrosion coating 32 of the first embodiment.

[0188] In this third example, the secondary material, i.e. the material of the secondary layers 233b, is undoped hexagonal tantalum nitride TaN.

[0189] This 232 multi-layer anti-corrosion coating can be deposited on the substrate 231 using the same device 50 shown schematically in FIG. 4 and described in the context of the first embodiment. Indeed, the main layers 233a can be deposited by co-sputtering as described above; the secondary layers 233b can for their part be deposited by high-power pulsed magnetron cathode sputtering using the first target 52 alone, that is to say by not applying any power to the second target 53.

[0190] Thus, it is possible to produce all 233 layers of the coating 232 in a single step and using a single device 50, by controlling over time the electrical polarizations applied to each of the targets 52, 53.

[0191] In particular, in this third example, the pressure in chamber 51 is set at 5 mTorr, or approximately 0.7 Pa. The gas mixture is composed of argon and nitrogen with 25% at nitrogen. The main layers are deposited with the same pulse parameters as those of the first embodiment. The secondary layers are deposited with the following pulse parameters: pulse width equal to 50 ps; pulse frequency equal to 1000 Hz; and pulse voltage equal to -700V.

[0192] The anti-corrosion performance of the main material has been described in the context of the first implementation example.

[0193] Figure 9 illustrates the results of corrosion tests on the secondary material. This cyclic voltammetry test was carried out under the same conditions as the test carried out for the first embodiment, except that the working electrode was tested in several phosphoric acid baths at increasing concentrations: 0.1 mol / L; 0.5 mol / L; and 1 mol / L.

[0194] The three curves 261, 262 and 263 thus correspond to the same working electrode in 316L stainless steel completely covered with an undoped hexagonal tantalum nitride coating.

[0195] Curve 261 corresponds to a bath concentration of 0.1 mol / L. Curve 262 corresponds to a bath concentration of 0.5 mol / L. Curve 263 corresponds to a bath concentration of 1 mol / L.

[0196] As can be seen in Figure 9, curves 261, 262 and 263, corresponding to the secondary material, also have significantly wider stability levels than those of the reference material 231 in 316L stainless steel.

[0197] This test also allows the measurement of corrosion potential and current for 316L stainless steel (Table 3) and undoped hexagonal tantalum nitride (Table 4) for these different bath concentrations. [Table 3] [Table 4]

[0198] Thus, the corrosion current l corr undoped hexagonal tantalum nitride grows much less quickly than that of 316L stainless steel with increasing acidity of the medium, thus revealing better resistance to corrosion.

[0199] Furthermore, Figure 10 illustrates the microstructure of a hexagonal tantalum nitride coating, in cross-section and from the front, deposited by a high-power pulsed magnetron sputtering process according to the present example. The scale shown at the bottom of each view corresponds to 1 μm. It can be seen from these two views that, in the same way as for its cubic counterpart in Figure 6, the microstructure of the coating is fine and homogeneous, which implies good mechanical strength with, in particular, good resistance to the propagation of cracks within the coating. For comparison, such a coating deposited by a conventional magnetron sputtering process results in a easily fractured columnar microstructure, as seen in Figure 11.

[0200] Furthermore, the inventors determined that the cubic and hexagonal phases of tantalum nitride possess significantly different Young's moduli. Indeed, the Young's modulus measured by nanoindentation of the cubic phase is 430 GPa while that of the hexagonal phase is 560 GPa.

[0201] As a result, cracks tend to be deflected at the interface between a main layer 233a and a secondary layer 233b. Therefore, the superposition of several alternating main layers 233a and secondary layers 233b makes it possible to significantly slow the propagation of cracks within the coating 232.

[0202] Finally, it is important to note that hexagonal tantalum nitride benefits from an even higher conductivity than cubic tantalum nitride, which further improves its electrical conduction function. Thus, at 160°C, the conductivity of cubic tantalum nitride deposited by high-power pulsed magnetron sputtering is equal to 4,045 S / cm.

[0203] In this third example, the primary material is doped cubic tantalum nitride while the secondary material is undoped hexagonal tantalum nitride. However, other multilayer configurations are also possible.

[0204] For example, the main material may be hexagonal tantalum nitride, or two-phase tantalum nitride, either cubic or hexagonal. The main material may also include a different doping element or one or more additional doping elements.

[0205] For example, the secondary material can also be doped. However, if the crystal system of the second material is the same as that of the main material, the doping will preferably be different from that of the main material.

[0206] Thus, in particular, in a fourth exemplary embodiment, the coating comprises alternating layers of doped hexagonal tantalum nitride and undoped hexagonal tantalum nitride.

[0207] In a fifth embodiment, the coating comprises alternating layers of doped hexagonal tantalum nitride and doped or undoped cubic tantalum nitride.

[0208] Figure 12 illustrates the operation of a cell 520 in a sixth exemplary embodiment. In this sixth example, the fuel cell 501 is a direct methanol fuel cell (DMFC).

[0209] In such a fuel cell 501, the fuel supplied to the anode 523 is methanol CH3OH while air is supplied to the cathode 525. Liquid water H2O is also supplied to the anode 523.

[0210] Electrolyte 524 consists of a proton exchange membrane capable of allowing H protons to pass through + while retaining the electrons e-. The proton exchange membrane also prevents the passage of any gas. Platinum, possibly alloyed with nickel, is used as a catalyst at both the anode 523 and the cathode 525.

[0211] Anode 523 is thus the seat of the following oxidation half-reaction: CH3OH + H2O CO2+6H + + 6th-

[0212] Cathode 525 is the seat of the following reduction half-reaction: 4H + + 4e- + O22H2O

[0213] Thus, overall, the operating equation of the fuel cell 501 is as follows: 2CH3OH + 3 O22CO2+ 4H2O

[0214] In such a proton exchange membrane cell, the membrane 524 acts as an acid electrolyte. It can be a membrane based on Nafion (registered trademark), i.e., a fluoropolymer copolymer based on sulfonated tetrafluoroethylene.

[0215] The terminal plates 511, 512 and / or the bipolar plates 521, 527 of this fuel cell 501 can then be configured in a manner analogous to the components presented above: they can thus comprise a non-conductive substrate and an anti-corrosion coating as described in any one of the examples above. The anti-corrosion coating then ensures the protection of the non-conductive substrate as well as the electrical conduction function of the component.

[0216] Figure 13 illustrates the operation of a cell 20 in the context of another exemplary embodiment. In this example, the fuel cell 1 is an alkaline fuel cell.

[0217] In such a fuel cell 1, the fuel supplied to the anode 23 is dihydrogen H2 while air is supplied to the cathode 25.

[0218] The electrolyte 24 consists of an aqueous solution of potassium hydroxide KOH capable of allowing the hydroxide ions OH' to pass through while retaining the electrons e-. The electrolyte also prevents the passage of any gas. Due to the alkaline environment, a non-precious metal can be chosen as the catalyst at the anode: for example, it can be iron, cobalt, or nickel. At the cathode, silver or iron can be used as a catalyst.

[0219] Anode 23 is thus the seat of the following oxidation half-reaction: 2H2+ 4OH- 4H2O + 2e-

[0220] Cathode 25 is the seat of the following reduction half-reaction: O2+ 2H2O + 4e- 4OH-

[0221] So, overall, the operating equation of fuel cell 1 is as follows: 2H2+ O22H2O

[0222] In such an alkaline electrolyte cell, the electrolyte 24 is an aqueous solution such that water molecules H2O are always present at the cathode 25 in order to allow the reduction half-reaction. The oxidation half-reaction at the anode 23 allows for its part to reconstitute the water molecules H2O consumed at the cathode 25 while producing an excess of water which is evacuated through the diffusion layer 22.

[0223] Due to this highly corrosive environment, the end plates 11, 12 and the bipolar plates 21, 27 must be able to resist corrosion while continuing to perform their electrical conduction function.

[0224] Figure 14 illustrates the operation of a cell 20 in another exemplary embodiment. In this example, the fuel cell 1 is a solid oxide fuel cell (SOFC).

[0225] In such a fuel cell 1, the fuel supplied to the anode 23 is dihydrogen H2 while air is supplied to the cathode 25.

[0226] Electrolyte 24 consists of a zirconia ceramic stabilized with yttrium oxide (YSZ) capable of allowing O ions to pass through 2- while retaining the electrons e-. This ceramic also prevents the passage of any gas. Due to the high operating temperature of such a battery, above 500°C, a A precious metal catalyst, such as platinum, is not necessary: ​​less expensive metals, such as nickel or cobalt, can be used.

[0227] Anode 23 is thus the seat of the following oxidation half-reaction: H2+ O 2 ' H2O + 2e-

[0228] Cathode 25 is the seat of the following reduction half-reaction: O2+ 4e- 2 O 2 -

[0229] So, overall, the operating equation of fuel cell 1 is as follows: 2H2+ O22H2O

[0230] Due to this highly corrosive environment, the end plates 11, 12 and the bipolar plates 21, 27 must be able to resist corrosion while continuing to perform their electrical conduction function.

[0231] Figure 15 illustrates the operation of a cell 520 in another exemplary embodiment. In this example, the fuel cell 501 is a molten carbonate fuel cell.

[0232] In such a fuel cell 501, the fuel supplied to the anode 523 is dihydrogen H2 while air is supplied to the cathode 525.

[0233] Electrolyte 524 consists of a molten mixture of lithium carbonates Li2CO3 and potassium carbonates K2CO3, forming a eutectic, in a porous matrix of aluminum oxide and lithium. Electrolyte 524 is capable of allowing CO3 ions to pass through 2 ' while retaining the electrons e-. The 524 electrolyte also prevents the passage of any gas. Due to the high operating temperature of such a battery, above 500°C, it is possible to choose a non-precious metal as a catalyst.

[0234] Anode 523 is thus the seat of the following oxidation half-reaction: H2+ CO3 2 - H2O + CO2+ 2e-

[0235] Cathode 525 is the seat of the following reduction half-reaction: O2+ 2CO2+ 4e- 2CO3 2 -

[0236] Thus, overall, the operating equation of the fuel cell 501 is as follows: 2H2+ O22H2O

[0237] Since the reduction half-reaction requires the consumption of carbon dioxide CO2 at the cathode 525 while the same amount of carbon dioxide CO2 is produced by the oxidation half-reaction at the anode 523, a recirculation line 528 is provided between the two diffusion layers 522 and 526 in order to conduct the carbon dioxide CO2 produced at the anode 523 to the cathode 525. If necessary, additional carbon dioxide CO2 can also be supplied from outside, in particular to initiate the process.

[0238] The terminal plates 511, 512 and / or the bipolar plates 521, 527 of this fuel cell 501 can then be configured in a manner analogous to the components presented above: they can thus comprise a non-conductive substrate and an anti-corrosion coating as described in any one of the examples above. The anti-corrosion coating then ensures the protection of the non-conductive substrate as well as the electrical conduction function of the component.

[0239] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense. It is also obvious that all the characteristics described with reference to a method are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a method.

Claims

Claims

1. Component for a fuel cell or electrolyzer, with acid electrolyte, alkaline electrolyte or solid oxide electrolyte or molten salt, comprising a substrate (31), electrically non-conductive, and an anti-corrosion coating (32) deposited on at least part of a surface of the substrate (31), in which the anti-corrosion coating (32) comprises at least one main layer based on tantalum nitride doped with one or more doping elements chosen from the family of transition metals and / or lanthanides.

2. Component according to claim 1, wherein the substrate (31) is made of polymeric material, in particular thermoplastic and / or elastomer.

3. A component according to claim 1 or 2, wherein the crystal system of the tantalum nitride of the main layer (32) is hexagonal or cubic.

4. Component according to any one of claims 1 to 3, in which the total dopant content within the main layer (32) is between 1 ppm and 10 at%, in particular between 10 ppm and 1 at%, in particular still between 0.2 and 0.5 at%.

5. A component according to any one of claims 1 to 4, wherein the main doping element is selected from zirconium, hafnium, nickel, vanadium, titanium, niobium, chromium and / or molybdenum.

6. Component according to any one of claims 1 to 5, wherein the thickness of the anti-corrosion coating (32) is between 5 nm and 5 pm, in particular between 10 nm and 1 pm, in particular between 100 nm and 300 nm.

7. Component according to any one of claims 1 to 6, wherein the anti-corrosion coating (232) comprises several superimposed layers (233a, 233b), in particular between 2 and 10 layers, wherein the material of the main layer (233a) constitutes a main material, and wherein the anti-corrosion coating (232) comprises at least one secondary layer (233b) based on a secondary material different from the main material.

8. A component according to claim 7, wherein the main material constitutes at least 30% by volume, in particular at least 50% by volume, of the anti-corrosion coating.

9. Component according to claim 7 or 8, in which the anti-corrosion coating comprises an alternation of layers based on the main material and the secondary material.

10. A component according to any one of claims 7 to 9, wherein the secondary material is tantalum nitride having a crystal system and / or doping different from the main material.

11. Fuel cell or electrolyzer, with acid electrolyte, comprising at least one component (30) according to any one of claims 1 to 10, in particular of the proton exchange membrane fuel cell (PEMFC), phosphoric acid fuel cell (PAFC) type, in particular supplied with gaseous fuel, in particular dihydrogen H2, direct methanol fuel cell (DMFC), direct ethanol fuel cell (DEFC), or direct ethylene glycol fuel cell (DEGFC), in particular configured to be supplied with methanol CH3OH, ethanol C2H5OH or ethylene glycol HOC2H4OH.

12. Fuel cell or electrolyser, with alkaline electrolyte, comprising at least one component (30) according to any one of claims 1 to 10, in particular of the type - alkaline fuel cell (AFC), - metal / air cell, or - direct urea fuel cell (DUFC).

13. Fuel cell or electrolyzer, with solid oxide electrolyte, comprising at least one component (30) according to any one of claims 1 to 10, in particular of the solid oxide fuel cell (SOFC), protonic ceramic fuel cell (PCFC), molten carbonate fuel cell (MCFC), molten carbonate electrolyzer (MCEC), - direct carbon fuel cell (DCFC), or direct urea fuel cell (DUFC) type.

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