Structured support electrode electrochemical cell

Abstract

Structured Electrode Electrochemical Cell The invention relates to an electrochemical cell unit comprising, in order of thickness: - a hydrogen support electrode comprising a first surface and a second surface, opposite each other, - a solid electrolyte comprising a first surface and a second surface, opposite each other, the first surface of the solid electrolyte facing the second surface of the hydrogen electrode, and - an oxygen electrode comprising a first surface and a second surface, opposite each other, the first surface of the oxygen electrode facing the second surface of the solid electrolyte, the hydrogen support electrode comprising at least one gas circulation channel formed in a hollow and opening at the level of the first surface of the hydrogen electrode and without opening at the level of the second surface of the hydrogen electrode.The invention relates to the optimization of a solid oxide cell, including solid oxide fuel cells and solid oxide electrolyzer cells. Figure for the abstract: Fig.1.

Description

Title of the invention: Electrochemical cell with structured support electrode technical field

[0001] The present invention relates to the optimization of a solid oxide cell, referred to as a SOC (Solid Oxide Cell), and in particular to the optimization of the support electrode through its structuring. This type of cell is used in systems for producing electricity from hydrogen and oxygen (solid oxide fuel cell, referred to as a SOFC) or hydrogen and oxygen from water vapor (solid oxide electrolysis cell, referred to as a SOEC). STATE OF THE ART

[0002] A SOC electrochemical cell is schematically represented by 3 layers, i.e., 2 electrodes separated by an electrolyte. The electrodes are the site of the electrochemical reactions and are electronically conductive, or even mixed electronic / ionic, while the electrolyte is solely ionically conductive.

[0003] SOFC fuel cells are electrochemical cells that produce electrical and thermal energy and use the chemical energy generated by the reaction of water formation from hydrogen and oxygen.

[0004] The operating principle of a SOFC cell is based on the following mechanism: oxygen from the air, which is supplied to the cathode, is dissociated to give O2- anions. The anions thus formed migrate through the electrolyte until they reach the anode, where they oxidize the hydrogen atoms supplied by the fuel. This reaction releases electrons and water.

[0005] A cell operating as a SOEC (Solid Oxide Electrolysis Cell) is a hydrogen-producing electrochemical cell whose operating principle is strictly the reverse of that of SOFCs. In an SOEC, water vapor is supplied to the cathode, and the water molecules are dissociated into hydrogen and O2- anions. The anions thus formed diffuse through the electrolyte to recombine as oxygen at the anode, while the hydrogen remains, along with the water vapor, at the cathode. This hydrogen can then be recovered for use as fuel in other applications.

[0006] Hydrogen is thus produced with a high yield, which makes this technology very relevant in the current energy context. Indeed, the increasing use Renewable energy sources, often intermittent, require an efficient means of storage, and the hydrogen carrier then makes perfect sense.

[0007] Developments in the materials and shaping processes used to manufacture electrochemical cells over the past fifteen years have led to high levels of performance. These advances make high-temperature technology compatible with hydrogen cost targets. However, certain aging mechanisms, related to the high operating temperature or specific to the high-temperature electrolysis (HTE) operating mode, actually limit the appeal of this new technology. These mechanisms are often relatively difficult to identify and depend on the test conditions (current density, percentage of vapor in the electrolyzed H2O / H2 mixture, conversion rate, temperature, etc.).

[0008] Initially, SOCs were optimized for operation in SOFC fuel cell mode. The reversibility of these electrochemical systems allows them to also operate in SOEC mode, which can also be called EHT, but different reaction mechanisms for these two operating modes result in different polarization or concentration overvoltages. This may also require different architectures and microstructures for supplying / removing reactants / reaction products. Regarding degradation mechanisms, some are identical for these two operating modes, and others are specific to electrolysis.

[0009] Several steps constituting the reaction mechanism take place within the electrodes and are not always clearly established. One proposed mechanism is as follows: first, water vapor diffuses through the electrode porosity to the nickel sites, triple points (ceramic oxide, nickel, porosity) where dissociative H2O adsorption occurs. The hydrogen produced diffuses from the reaction sites to the electrode surface through the electrode porosity. Oxygen adsorbed on the surface of the nickel particles diffuses to the nickel / ionic conductor interface (YSZ). Then, the charge transfer reaction takes place between the adsorbed oxygen and the electronic charges conducted by the nickel.

[0010] Electrodes are highly heterogeneous porous media, the site of local mechanisms that explain the macroscopic behavior of electrolysis cells. The microstructure of the electrodes thus plays a key role in the electrochemical performance of the cells. For example, the diffusion of gases through the thick substrate formed by the electrode of a cell induces strong concentration overpotentials that can limit the cell's efficiency at high currents. Furthermore, electrochemical degradation or mechanical damage, which appears in operation under current or during thermal or 'redox' cycles, are often linked to microstructural evolutions of porous electrodes.

[0011] Therefore, optimizing the microstructure of the electrodes is an essential step towards obtaining high-performance, robust, and durable cells. ABSTRACT

[0012] To achieve this objective, according to one embodiment, an electrochemical cell unit is provided comprising, in order of its thickness: - a hydrogen support electrode comprising a first surface and a second surface, opposite each other, - a solid electrolyte comprising a first surface and a second surface, opposite each other, the first surface of the solid electrolyte facing the second surface of the hydrogen support electrode, and - an oxygen electrode comprising a first surface and a second surface, opposite each other, the first surface of the oxygen electrode facing the second surface of the solid electrolyte, the hydrogen support electrode comprising at least one circulation channel for at least one gas, formed in a hollow and opening at the level of the first surface of the hydrogen support electrode and without opening at the level of the second surface of the hydrogen support electrode.

[0013] This arrangement has the advantage of allowing for a better supply of gas to the electrode, and in particular to the hydrogen electrode acting as a support electrode. This structure of the hydrogen support electrode also simplifies the interconnecting plates in the cell stack. The presence of at least one circulation channel, advantageously for a gas such as hydrogen or water vapor, helps to limit overvoltages related to the diffusion of hydrogen and water vapor in the support electrode of the cell unit.The distance to be traveled in the support electrode for the gases is reduced, the thickness of the support electrode being reduced at the level of at least one circulation channel allowing the gases to more easily reach the electrochemical reaction sites which are preferentially located within a thickness of 20 pm from the second surface of the hydrogen support electrode advantageously interfacing with the solid electrolyte.

[0014] According to another aspect, the invention relates to a stack comprising at least one electrochemical cell unit as described above. The stack comprises a first interconnector intended to be arranged with respect to the first surface of the hydrogen support electrode and / or a second interconnector intended to be arranged with respect to the second surface of the oxygen electrode. The first interconnector comprises a first flat surface intended to be oriented with respect to the first surface of the hydrogen support electrode. The configuration of the cell unit allows for a stack that eliminates the need for diffusion channels in Interconnectors. Interconnectors linking the different cell units in a stack advantageously have flat surfaces which help to facilitate their manufacture and limit their cost. BRIEF DESCRIPTION OF THE FIGURES

[0015] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings in which:

[0016] [Fig.1] Fig.1 represents a cross-sectional view, along the thickness, of a cell unit according to an embodiment of the invention.

[0017] [Fig.2] Fig.2 represents a cross-sectional view, along the thickness, of a cell unit according to another embodiment.

[0018] [Fig.3] The [Fig.3] represents a cross-sectional view, along the thickness, of a stack comprising the cell unit according to the [Fig.1].

[0019] [Fig.4] Fig.4 represents a cross-sectional view, according to thickness, of the stacking according to a variant of Fig.3.

[0020] [Fig.5] Fig.5 represents a front view of the first surface of the hydrogen electrode according to one embodiment.

[0021] [Fig.6] Fig.6 represents a detailed view according to Fig.5.

[0022] The drawings are given by way of example and are not limiting of the invention. These are schematic representations of the principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. In particular, the layer thicknesses are not representative of reality. DETAILED DESCRIPTION

[0023] Before proceeding with a detailed review of embodiments of the invention, optional features that may be used in combination or alternatively are listed below: - According to an example, the at least one circulation channel 100 has a depth P extending along the thickness Ep of the electrochemical cell unit 1, a width 1 extending transversely to the thickness Ep and a length L extending transversely to the thickness Ep and to the width 1, the at least one circulation channel 100 being open along its entire length L and its width 1; - According to an example, at least one circulation channel 100 exhibits a variation in its depth P; According to one example, at least one circulation channel 100 is arranged in the form of a spiral extending in a plane parallel to the second surface 202 of the hydrogen electrode support 200; According to one example, the electrochemical cell unit 1 includes a gas inlet arranged at the center 1002 of the spiral; According to one example, the depth P of the circulation channel 100 is increasing from the center 1002 of the spiral, preferentially continuous; According to one example, at least one circulation channel 100 is formed of grooves arranged parallel to each other and extending along a longitudinal direction perpendicular to the thickness Ep of the electrochemical cell unit 1; According to one example, the grooves have a decreasing depth P between them towards the center 1000 of the electrochemical cell unit; According to an example, the electrochemical cell unit 1 has a groove density gradient, preferably between the center 1000 of the cell unit and its edges 1001, the use of a depth gradient of at least one circulation channel and a groove density gradient allows the pressure loss within the cell unit to be managed and thus to be able to supply different parts of the cell unit in order to have homogeneous operation of the cell unit in terms of current density; According to one example, at least one circulation channel 100 has a maximum depth P of 80% of the thickness 10 of the hydrogen support electrode 200, preferably 2 / 3 of the thickness (6) of the hydrogen support electrode 200; According to one example, at least one circulation channel 100 represents a maximum of 50% of the first surface 201 of the hydrogen electrode support 200; According to one example, the electrochemical cell unit aperture 1 includes an interface element arranged with respect to the first surface 201 of the hydrogen electrode support 200 comprising communicating passages arranged with respect to said first surface 200; According to one example, the interface element is a contact grid 700 arranged on the first surface 200 of the hydrogen electrode support 200 and advantageously intended to come into contact with an interconnector; According to one example, the interface element is a contact layer 6 comprising at least one complementary channel 603 to at least one circulation channel 100 of the hydrogen electrode support 200 arranged with respect to the first surface 201 of the hydrogen electrode support 200 and advantageously designed to come into contact with an interconnector. With this configuration, the contact between the hydrogen electrode support and the interconnector is sufficient.

[0024] For the remainder of the description, 'top' and 'bottom', or their derivatives, refer to a relative positioning quality of a unit cell element or stacking element as shown in the figures, with 'top' oriented away from the ground and 'bottom' oriented towards the ground. The upper end is located at the top and the lower end is located at the bottom.

[0025] Vertical means that which is directed along the thickness of the stack or cell unit, that is to say along the principal direction of extension of the stack or cell unit, and horizontal means that which is perpendicular to the vertical. The top and bottom being vertically opposite.

[0026] A transverse direction is understood to be a direction perpendicular to a longitudinal direction. The longitudinal direction is understood to be a direction perpendicular to the thickness of the stack or cell unit. A transverse section is a section perpendicular to the longitudinal axis. A cross-section is a section along the thickness of the stack or cell unit. A longitudinal section is a section perpendicular to the thickness of the stack or cell unit.

[0027] A parameter "approximately equal to / greater than / less than" or "of the order of" a given value means that this parameter is equal to / greater than / less than the given value, to within 10% or even 5% of that value.

[0028] For the purposes of this disclosure, the expression "A and / or B" means (A), (B) or (A and B). For the purposes of this disclosure, the expression "A, B and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0029] The terms "first", "second" and "third", "additional", etc. are used simply as labels, and are not intended to impose numerical requirements on their objects.

[0030] The term "upper," used in particular to describe a face of a layer, here serves only to designate one of the two faces of a layer (the other being the lower face), without making any assumptions about the relative position of the faces along a vertical direction. The upper face could thus also have been called the front face, as opposed to a back face.

[0031] The shapes or dimensions given for certain components of the present invention are always only indicative and are understood to include substantially equivalent shapes and dimensions.

[0032] It is specified that within the framework of the present invention, the terms "on", "overcome", "cover", "above", "underlying", or "below", or their equivalents, do not necessarily mean "in contact with". For example, the deposit of a first layer on top of a second layer does not necessarily mean that the two layers are directly in contact with each other, but it does mean that the first layer at least partially covers the second layer either by being directly in contact with it, or by being separated from it by at least one other layer or at least one other element.

[0033] The present invention relates to an electrochemical cell unit 1. The electrochemical cell unit is intended to be used to form SOFC type solid oxide fuel cells and SOEC solid oxide electrolyzers.

[0034] The cell unit 1 comprises a superposition of layers including an anode, a cathode and a solid electrolyte 300 arranged between the anode and the cathode.

[0035] The hydrogen electrode 200 advantageously serves as the site for water reduction reactions or, alternatively, hydrogen oxidation reactions. The hydrogen electrode is the electrode around which hydrogen and water vapor circulate.

[0036] According to a preferred embodiment, the electrochemical cell unit 1 is of the support electrode type. The support electrode is understood to be an electrode that provides mechanical support for the cell unit. More specifically, according to the invention, the hydrogen electrode 200 preferentially provides mechanical support for the cell unit 1. The support is understood to be the electrode on which the weight of the rest of the cell unit is exerted. Preferably, the support electrode is the lower electrode of the cell unit. According to this embodiment, the hydrogen electrode 200 is a layer with a minimum thickness 10 of approximately 400 µm and, for example, approximately 500 µm. Advantageously, the electronic conductivity of the support electrode is greater than 1000 S / cm. The cell unit with a support electrode makes it possible to reduce the operating temperature while maintaining an acceptable ohmic drop.Support electrode cells generally operate between 600° and 800°C, greatly limiting degradation problems while allowing for the use of cheaper metal alloy interconnect plates.

[0037] In the following description, the terms hydrogen electrode, support electrode or hydrogen support electrode are used interchangeably.

[0038] By way of example, the hydrogen electrode 200 is a cermet. For example, the hydrogen electrode 200 is composed of a mixture of an ionically conductive oxide and a catalytic metal, most often nickel. This metal exhibits strong catalytic activity with respect to the reduction of water and therefore the production of hydrogen. Furthermore, thanks to its high electronic conductivity (4.5 × 10³ S.cm⁻¹ at 800°C), nickel ensures electronic continuity in the electrode. The ceramic network accommodates the thermomechanical stresses related to a difference in the coefficient of thermal expansion (CTE) between that of nickel (16.5 × 10⁶ K₁) and that of the cermet. of the electrolyte (10.5 x 10⁶ Kl for 8YSZ). For example, a 40 v / v Ni - 60 v / v 8YSZ cermet has a CET of approximately 13 x 10⁶ Kl. Finally, thanks to its high ionic conductivity, this ceramic network allows the electrochemical reaction to be delocalized to a volume close to the interface with the solid electrolyte 300.

[0039] The hydrogen electrode 200 comprises a first surface 201 and a second surface 202, opposite each other and preferably parallel. The first surface 201 and the second surface 202 extend along a longitudinal plane, perpendicular to the thickness of the cell unit 1. Preferably, the first surface 201 and the second surface 202 are of identical dimensions. Preferably, the second surface 202 is planar.

[0040] By way of non-limiting example, the hydrogen electrode is made of a mixture of nickel oxide (NiO) and doped zirconium oxide (typically doped with yttrium oxide at a level of 8 mol%). The mixtures conventionally used have a NiO content of approximately 50 to 70% by mass.

[0041] According to the invention, the cell unit 1 is characterized in that it comprises a structure formed within its thickness. Advantageously, it is the hydrogen electrode 200 that comprises a structure.

[0042] The structure of the hydrogen electrode 200 is intended to allow better gas supply to the electrode despite its thickness of support electrode.

[0043] According to the invention, the cell unit 1 comprises at the level of the hydrogen electrode 200 called support electrode at least one circulation channel 100.

[0044] In the following description, reference is made to a circulation channel 100 without limitation. The hydrogen electrode 200, referred to as the support electrode, may comprise several circulation channels 100.

[0045] The circulation channel 100 is advantageously intended to allow the circulation of a gas or a mixture of gases such as water vapor and / or dihydrogen.

[0046] The circulation channel 100 is formed in a hollow from the first surface 201 of the hydrogen electrode 200. The circulation channel 100 opens at the first surface 201 of the hydrogen electrode 200. Advantageously, the circulation channel 100 does not open at the second surface 202 of the hydrogen electrode 200. The circulation channel 100 is formed within the thickness of the hydrogen electrode 200 preferably in only a part so as to maintain a thickness 11 of the hydrogen electrode 200 directly above the circulation channel 100. Preferably, the minimum thickness 11 of the hydrogen electrode 200 is on the order of 20 pm.

[0047] The circulation channel 100 has a depth P extending along the thickness Ep of the cell unit, a width 1 extending transversely to the thickness Ep and a length L extending transversely to the thickness Ep and to the width 1.

[0048] According to a preferred embodiment, the circulation channel 100 opens over its entire surface in a plane parallel to the plane of the first surface 201 of the hydrogen electrode 200.

[0049] According to one possibility, the circulation channel 100 has a depth P representing a maximum of 80% of the thickness 10 of the hydrogen electrode 200. Preferably, the circulation channel 100 has a depth P representing a minimum of 1 / 3 of the thickness 10 of the hydrogen electrode 200. This dimension of the circulation channel 100 makes it possible to improve gaseous diffusion without weakening the cell unit by getting too close to the solid electrolyte 300.

[0050] Preferably, the flow channel 100 has a width 1 between 25 pm and 150 pm. Advantageously, the surface area of ​​the flow channel 100 taken transversely to the thickness Ep is less than or equal to 50% of the surface area of ​​the second surface 202 of the hydrogen electrode 200. This selection of the minimum remaining surface area of ​​the first surface 201 of the hydrogen electrode 200 ensures electrical contact with the interconnector 900 configured to be aligned with this first surface 101.

[0051] The geometry of the circulation channel 100 is, for example, in cross-section as illustrated in figures 1 to 4, of a parallelepiped or triangular shape, one of the vertices being oriented towards the second surface 202 of the hydrogen electrode 200.

[0052] According to one embodiment, the circulation channel 100 is arranged in the form of a spiral extending in a longitudinal plane perpendicular to the thickness 10 of the hydrogen electrode 200.

[0053] Preferably, the turns forming the spiral are regularly spaced, corresponding for example to an Archimedean spiral.

[0054] According to an alternative, the turns have an increasing spacing from the center 1002 of the spiral towards its circumference 1003 of the spiral, corresponding for example to a logarithmic spiral.

[0055] According to yet another alternative, the turns have a decreasing spacing from the center 1002 of the spiral towards its circumference 1003 the spiral corresponding for example to an algebraic spiral.

[0056] The last two alternatives allow the turns density to be varied to allow homogeneous operation of the cell unit in terms of current density.

[0057] According to one embodiment, the circulation channel 100 has a variable depth P. In one possibility, the depth P of the circulation channel 100 increases from the center 1002 of the spiral towards its circumference 1003. The increase in depth P is preferably continuous and gradual along the circulation channel 100. The depth P thus increases progressively from the center 1002 of the spiral along its turns. This arrangement allows for a decreasing pressure drop between the inlet and outlet. This enables a potentially more homogeneous supply throughout the cell.

[0058] Advantageously, the spiral circulation channel 100 is supplied with gas at its center 1002 by an external gas inlet to the cell unit is advantageously formed at the interconnector 900 for example by an opening of 5 to 10mm in diameter.

[0059] According to another embodiment, the circulation channel 100 includes grooves.

[0060] Advantageously, the grooves are arranged parallel to each other. The grooves advantageously extend along a longitudinal direction perpendicular to the thickness Ep of the cell unit 1.

[0061] According to one possibility, at at least one of their ends the grooves are in fluidic communication allowing the circulation of gas between them. The grooves thus form a circulation channel 100. This arrangement allows gas to enter on one side of the cell and to exit on the opposite side, preferably via supply and recovery channels.

[0062] According to another possibility, the grooves are not in fluidic communication with each other.

[0063] According to one embodiment, the grooves have a variable depth P. Preferably, the depth P of successive grooves decreases towards the center 1000 of the cell unit 1.

[0064] According to one embodiment, the spacing between the grooves is constant as illustrated in [Fig.1].

[0065] According to another embodiment, the grooves have variable spacing between them. In a preferred embodiment, the spacing between the grooves decreases from the center 1000 towards the edges 1001 of the cell unit 1, as illustrated in [Fig. 2]. In another embodiment, the spacing between the grooves increases from the center 1000 towards the edges 1001 of the cell unit 1. The density of the grooves is thus variable at the first surface 201 of the hydrogen electrode support 200. Advantageously, this embodiment allows for different feeding of certain areas of the cell, which can help to homogenize the densities of current throughout the cell, and therefore potentially limit cell aging.

[0066] The superposition of the layers of the cell unit 1 is done along the thickness 10 of the hydrogen electrode layer 200. The thickness 10 of the hydrogen electrode layer 200 is parallel to the thickness EP of the cell unit 1.

[0067] The cell unit 1 comprises, with respect to the first surface 201 of the hydrogen electrode 200, a solid electrolyte 300. The solid electrolyte 300 is a layer comprising a first surface 301 and a second surface 302, opposite each other and preferably parallel. The first surface 301 and the second surface 302 extend along a longitudinal plane, perpendicular to the thickness El of the cell unit 1. Preferably, the first surface 301 and the second surface 302 are planar. Preferably, the first surface 301 and the second surface 302 are of identical dimensions. Preferably, the first surface 301 and the second surface 302 of the solid electrolyte 300 are of substantially equivalent dimensions to the second surface 202 of the hydrogen electrode 200. The solid electrolyte 300 is an electrolytic membrane which constitutes the separation between the two compartments of a cell.As such, it must be perfectly dense to be impermeable to gas. Advantageously, the second surface 202 of the hydrogen electrode 200 is arranged in contact with the first surface 301 of the solid electrolyte 300. By way of non-limiting example, conventional electrolyte materials are zirconium oxides, doped with yttrium or scandium oxides at a level of 3 to 10 mol%.

[0068] The cell unit 1 comprises, with respect to the second surface 302 of the solid electrolyte 300, an oxygen electrode 400. The oxygen electrode 400 has a first surface 401 and a second surface 402, opposite each other and preferably parallel. The first surface 401 and the second surface 402 extend along a longitudinal plane perpendicular to the thickness Ep of the cell unit 1. Preferably, the first surface 401 and the second surface 402 are of identical dimensions. Preferably, the first surface 401 and the second surface 402 of the oxygen electrode 400 are smaller than the second surface 302 of the solid electrolyte 300. Preferably, the first surface 401 and the second surface 402 of the oxygen electrode 400 are planar. The oxygen electrode is the electrode through which the air, and therefore oxygen, circulates.As a non-limiting example, oxygen electrode materials are classically of perovskite structure (ABO3). One of the materials currently most commonly used is (LaSr)(CoFe)O3.

[0069] Preferably, the oxygen electrode 400 is configured so as not to cover the entire second surface 302 of the solid electrolyte 300. Preferably, the oxygen electrode 400 leaves the border of the second surface 302 of the solid electrolyte 300 free so as to form a frame without oxygen electrode 400. As an example, 5 to 10% of the surface of the solid electrolyte 300 is left free in order to position the sealing area there to allow direct contact between the sealing solution and a dense material such as the solid electrolyte.

[0070] According to one possibility, the cell unit 1 comprises a barrier layer 500 arranged between the solid electrolyte 300 and the oxygen electrode 400. More specifically, the barrier layer 500 is arranged between the second surface 302 of the solid electrolyte 300 and the first surface 401 of the oxygen electrode 400. The barrier layer 500 has a first surface 501 and a second surface 502 that are opposite to each other and preferably parallel. The first surface 501 and the second surface 502 extend along a longitudinal plane perpendicular to the thickness Ep of the cell unit 1. Preferably, the first surface 501 and the second surface 502 are planar. Preferably, the first surface 501 and the second surface 502 have identical dimensions. Preferably, the first surface 501 and the second surface 502 of the barrier layer 500 are of identical dimensions to the second surface 402 of the oxygen electrode 400.The 500 barrier layer is designed to limit the diffusion of elements and the reactivity between the oxygen electrode and the electrolyte material (typically strontium and lanthanum). Indeed, without this barrier layer, insulating phases can form during cell manufacturing or operation, impairing initial performance and durability.

[0071] According to one possibility, the cell unit 1 comprises at least one interface element arranged with respect to the first surface 201 of the hydrogen support electrode 200. The interface element is intended to optimize the circulation and diffusion of gas towards the hydrogen electrode 200. Preferably, the interface element comprises communicating passages arranged with respect to said first face and advantageously configured to ensure the circulation of gas towards the first surface 201 of the hydrogen support electrode 200.

[0072] According to a first possibility, the interface element is a first contact layer 600.

[0073] By way of example, the cell unit 1 includes a first contact layer 600 arranged with regard to the first surface 201 of the hydrogen electrode 200.

[0074] The first contact layer 600 has a first surface 601 and a second surface 602, opposite each other and preferably parallel. The first surface 601 and the second surface 602 extend along a longitudinal plane perpendicular to the thickness Ep of the cell unit 1. Preferably, the first surface 601 and the second surface 602 are of identical dimensions. Preferably, the first surface 601 and the second surface 602 of the first contact layer 600 are of identical dimensions to those of the hydrogen electrode 200. Preferably, the first surface 601 and the second surface 602 of the first contact layer 600 are discontinuous. According to one embodiment, the first contact layer 600 comprises at least one complementary channel 603 arranged with respect to the circulation channel 100. The first contact layer 600 is formed by an alternation of hollows and studs 604 arranged to form a complementary channel 603 to the circulation channel 100 of the hydrogen electrode 200. Advantageously, the second surface 602 of the first contact layer 600 is arranged in contact with the first surface 201 of the hydrogen electrode 200. The contact layer makes it possible to reduce the contact resistances with the interconnectors.The 600 contact layer advantageously exhibits better electronic conductivity of the hydrogen electrode, for example because it is made of pure nickel.

[0075] By way of example, the cell unit 1 includes a second contact layer 800 arranged with respect to the second surface 402 of the oxygen electrode 400.

[0076] The first contact layer 800 has a first surface 801 and a second surface 802, opposite each other and preferably parallel. The first surface 801 and the second surface 802 extend along a longitudinal plane perpendicular to the thickness Ep of the cell unit 1. Preferably, the first surface 801 and the second surface 802 are of identical dimensions. Preferably, the first surface 801 and the second surface 802 of the second contact layer 800 are smaller than those of the second surface 302 of the solid electrolyte 300. Preferably, the second contact layer 800 has a surface identical to that of the oxygen electrode 400. The contact layer 800 is intended to ensure the lowest possible contact resistance between the interconnector and the oxygen electrode.The contact layer 800 advantageously exhibits improved electronic conductivity of the oxygen electrode, for example, because it is made of pure nickel. Alternatively, the interface element is a contact grid 700 arranged with respect to the first surface 201 of the hydrogen electrode 200. The contact grid 700 has a first surface 701 and a second surface 702, opposite each other and preferably parallel. The first surface 701 and the second surface 702 extend along a longitudinal plane perpendicular to the thickness Ep of the cell unit 1. Preferably, the first surface 701 and the second surface 702 are of identical dimensions. Preferably, the first surface 701 and the second surface 702 of the contact grid 700 are of identical dimensions to those of the hydrogen electrode 200. Preferably, the first surface 701 and . The second surface 702 of the contact grid 700 is flat. In one embodiment, the contact grid 700 is porous and includes passages allowing the preferential circulation of gases such as dihydrogen and water vapor between the first surface 701 and the second surface 702. The contact grid 700 advantageously has a dual role: improving contact resistance, as with the contact layers 600 and 800, and acting as a gas diffuser.

[0077] According to another aspect, the invention relates to a stack comprising a cell unit 1 as described above and a first interconnector 900 arranged with respect to the first surface 201 of the hydrogen electrode 200. Preferably, the interconnector 900 has a surface with respect to the hydrogen electrode 200 that is larger than the first surface 201 of the hydrogen electrode 200 and / or larger than the first surface 301 of the solid electrolyte 300. In one possibility, the stack comprises a second interconnector (not shown) arranged with respect to the second surface 402 of the oxygen electrode 400. Preferably, the second interconnector is arranged with respect to the second surface 802 of the contact layer 800.

[0078] Advantageously, the cell unit one according to the invention allows the use in the stack of a first interconnector 900 comprising a first surface 901 and a second surface 902, opposite each other, of which the second surface 902 is flat and intended to be in view of the first surface 201 of the hydrogen electrode 200. The second surface 902 of the interconnector 900 advantageously does not include any relief intended for the distribution of gas.

[0079] According to one aspect, the invention relates to a method for manufacturing a cell unit 1 as described above.

[0080] The manufacture of the cell unit 1 and more particularly the superposition of the different layers is carried out by the various techniques known to a person skilled in the art.

[0081] Regarding the formation of at least one circulation channel 100, formed in a hollow and opening onto the first surface of the hydrogen electrode 200, this is achieved by strip casting, calendering, or micromachining. Preferably, the formation of at least one circulation channel 100 is achieved by laser micromachining. Forming the circulation channel 100 from the ground allows for control of the energy supplied in order to significantly structure the supporting hydrogen electrode without compromising the quality of the solid electrolyte 300, the quality of which is essential for the performance and durability of the cell unit.

[0082] By way of example, a cell unit according to the invention is produced by an INNOSLAB laser of the Edgewave brand (model BX60). This is an Nd-YAG laser with a power of 30W.

[0083] The following parameters were used:

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090] - Laser power = 100% or 30W - Laser speed when on = 1495 mm / s - Laser speed off (jump) = 3000 mm / s The laser beam before the lens is directed by two galvanometric mirrors, which imposes physical constraints on the beam's movement. Each marking vector is divided into microvectors, and the length and duration of these microvectors are configurable. The marking speed is set based on these two parameters. The duration of a microvector is given in ps (seconds) and its length in LSB (lengths per second), equivalent to one millimeter per byte. With a 220 x 220 mm field lens as used, one LSB is equivalent to 3.74 pm. The step size is set at 20 LSB, and the step interval at 50 ps. The following parameters were chosen to obtain the appropriate definition of the structure: - ON delay = 100 ps - OFF delay = 100 ps Regarding the laser beam, - The width of the well is fixed at 9 inches - The pump frequency is set at 100kHz - The number of repetitions is set at 500. A spiral-shaped support structure (50mm in diameter) was thus created. The pitch between the turns is 445 pm, as illustrated in figures 5 and 6. The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention. List of references - 1. Electrochemical cell unit - 10. Thickness of the hydrogen electrode support - 11. Thickness of the hydrogen electrode support directly above a channel of traffic - 100. Circulation channel - 200. Hydrogen electrode - 201. First surface - 202. Second surface - 300. Solid electrolyte - 301. First surface - 302. Second surface - 400. Oxygen electrode - 401. First surface - 402. Second surface 500. Barrier Layer 501. First surface 502. Second surface 600. First contact layer 601. First surface 602. Second surface 603. Supplementary Channel 604. Plot 700. Contact grid 701. First surface 702. Second surface 800. Second contact layer 801. First surface 802. Second surface 900. First interconnector 901. First surface 902. Second surface 1000. Cell unit center 1001. Cell unit edges 1002: center of the spiral 1003. Circumference of the spiral Ep. Thickness of the cell unit P. Depth of the circulation channel 1. Width of the circulation channel L. Length of the circulation channel

Claims

Demands

1. An electrochemical cell unit (1) comprising, in order of its thickness: - a hydrogen support electrode (200) comprising a first surface (201) and a second surface (202), opposite each other, - a solid oxide electrolyte (300) comprising a first surface (301) and a second surface (302), opposite each other, the first surface (301) of the solid oxide electrolyte (300) facing the second surface (202) of the hydrogen support electrode (200), and - an oxygen electrode (400) comprising a first surface (401) and a second surface (402), opposite each other, the first surface (401) of the oxygen electrode (400) facing the second surface (302) of the solid oxide electrolyte (300), characterized in that the hydrogen electrode support (200) includes at least one circulation channel (100) for at least one gas,formed in a hollow shape and opening at the level of the first surface (201) of the hydrogen support electrode (200) and without opening at the level of the second surface (202) of the hydrogen support electrode (200), and that at least one circulation channel (100) has a depth (P) extending along the thickness (Ep) of the electrochemical cell unit (1), a width (1) extending transversely to the thickness (Ep) and a length (L) extending transversely to the thickness (Ep) and to the width (1), the at least one circulation channel (100) being open along its entire length (L) and its width (1).

2. Electrochemical cell unit (1) according to the preceding claim wherein at least one circulation channel (100) has a depth variation (P).

3. Electrochemical cell unit (1) according to any one of the preceding claims wherein at least one circulation channel (100) is arranged in the form of a spiral extending in a plane parallel to the second surface (202) of the hydrogen support electrode (200).

4. Electrochemical cell unit (1) according to the preceding claim comprising a gas inlet arranged at the center (1002) of the spiral.

5. Electrochemical cell unit (1) according to any one of the two preceding claims in combination with claim 2 wherein, the depth (P) of the circulation channel (100) is increasing from the center (1002) of the spiral.

6. Electrochemical cell unit (1) according to any one of claims 1 to 2 in which at least one circulation channel (100) is formed of grooves arranged parallel to each other and extending along a longitudinal direction perpendicular to the thickness (Ep) of the electrochemical cell unit (1).

7. Electrochemical cell unit (1) according to the preceding claim in which the grooves have a depth (P) decreasing towards the center (1000) of the electrochemical cell unit.

8. Electrochemical cell unit (1) according to any one of the two preceding claims having a groove density gradient, preferably between the center (1000) of the cell unit and its edges (1001).

9. Electrochemical cell unit (1) according to any one of the preceding claims wherein the at least one circulation channel (100) has a maximum depth (P) of 80% of the thickness (10) of the support hydrogen electrode (200), preferably 2 / 3 of the thickness (6) of the support hydrogen electrode (200).

10. Electrochemical cell unit (1) according to any one of the preceding claims wherein at least one circulation channel (100) represents a maximum of 50% of the first surface (201) of the hydrogen support electrode (200).

11. Electrochemical cell unit opening (1) according to any one of the preceding claims comprising an interface element arranged with respect to the first surface (201) of the hydrogen electrode support (200) comprising communicating passages arranged with respect to said first surface (200).

12. Electrochemical cell unit (1) according to the preceding claim, wherein the interface element is a grid of contact (700) arranged on the first surface (200) of the hydrogen electrode support (200).

13. Electrochemical cell unit (1) according to claim 11 wherein the interface element is a contact layer (6) comprising at least one channel complementary (603) to at least one circulation channel (100) of the support hydrogen electrode (200) arranged with respect to the first surface (201) of the support hydrogen electrode (200).

14. Stack comprising at least one electrochemical cell unit (1) according to any one of the preceding claims characterized in that it comprises a first interconnector (900) intended to be arranged with respect to the first surface (201) of the hydrogen support electrode (200) and / or a second interconnector intended to be arranged with respect to the second surface (402) of the oxygen electrode (400), the first interconnector (900) comprising a first flat surface (901) intended to be with respect to the first surface (201) of the hydrogen support electrode (200).

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