Method for manufacturing a sealed high-temperature electrochemical cell unit and a cell unit obtained thereby

Abstract

The invention relates to a method for manufacturing an electrochemical cell unit comprising, in the following order in the direction of the thickness thereof, a hydrogen electrode comprising a first face and a second face opposite one another and a solid electrolyte comprising a first face and a second face opposite one another, the first face of the solid electrolyte facing the second face of the hydrogen electrode, the method comprising the following steps: positioning a seal in a first state in the form of a strip on the second face of the solid electrolyte at the edge of the second face, then treating the seal so as to make the seal transition into a second state, referred to as the functional state, that is more gas-tight and adheres better to the second face of the solid electrolyte than the first state, the treatment being carried out before any potential step of stacking to form a stack.

Description

[0001] "Method for manufacturing a sealed high-temperature electrochemical cell unit and a cell unit obtained"

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The present invention relates to the functionalization of a high-temperature SOC (Solid Oxide Cell) electrochemical cell unit. This type of cell unit is used in systems for producing electricity from hydrogen and oxygen (SOFC fuel cell mode for Solid Oxide Fuel Cell) or hydrogen and oxygen from water vapor (SOEC electrolyzer mode for Solid Oxide Electrolyzer Cells).

[0004] STATE OF THE ART

[0005] A high-temperature electrochemical cell unit (SOC) is schematically represented by 3 layers, i.e. 2 electrodes separated by an electrolyte. The electrodes are the site of electrochemical reactions, and are electronically conductive, or even mixed electronic / ionic, while the electrolyte is only ionically conductive.

[0006] Planar electrochemical cell units can be arranged one above the other in a stacked arrangement, for example 100 to 200 electrochemical cell units in a cell, the individual electrochemical cell units being electrically arranged in series. These cell units are integrated into stacks to increase the production of electricity or hydrogen. These stacks form, for example, fuel cells and are often referred to as stacks. In these stacks of cell units, seals must be ensured at various levels: between the hydrogen and oxygen compartments of the cell unit, from the outside, and at each gas inlet / outlet. In the case of a cell unit with a support electrode, these seals are even more difficult to achieve since one entire side, that of the support electrode commonly formed by the hydrogen electrode, consists of a porous support.Only the electrolyte accessible on the oxygen side can serve as a sealing zone with a dense material. Seals in stacks are therefore often carried out during assembly, with the creation of joints in the areas of the stack requiring it, and at the level of the electrochemical cell unit at the periphery of the oxygen-side cell unit in contact with the electrolyte. This therefore requires the deposition of a sealing solution (often glasses or glass-ceramics) at each level, without the possibility of validating the cold seal, before formation of the glass-ceramic.

[0007] It is therefore necessary to propose a solution that simplifies the assembly of the stack while having a seal that is easier to implement and test.

[0008] SUMMARY OF THE INVENTION

[0009] To achieve this objective, according to one embodiment, a method is provided for manufacturing an electrochemical cell unit comprising, in order according to its thickness, a hydrogen electrode comprising a first face and a second face, opposite each other, and a solid electrolyte comprising a first face and a second face opposite each other, the first face of the solid electrolyte facing the second face of the hydrogen electrode, and advantageously an oxygen electrode comprising a first face and a second face, opposite each other, a first face of the oxygen electrode facing the second face of the solid electrolyte, the method comprising the following steps: - positioning a seal in a first state, advantageously in the form of a strip, on the second face of the solid electrolyte, preferably at the edge of said second face,then - treatment of the seal intended to bring the seal into a second so-called functional state, advantageously more gas-tight and / or advantageously more adherent to the second face of the solid electrolyte than the first state, the treatment being carried out before a possible step of stacking in the form of a battery and advantageously a formation, with respect to the second face of the solid electrolyte, of the oxygen electrode comprising a first face and a second face, opposite one another, the seal forming a frame around the oxygen electrode. This method makes it possible to ensure sealing of the electrochemical cell unit independent of the stack, which reduces sealing problems during the formation of the stack of cell units.,

[0010] According to another aspect, the invention relates to a method of manufacturing a stack of cells comprising after the method of manufacturing a cell unit as mentioned above a step of stacking several cell units in the form of a stack.

[0011] According to another aspect, the invention relates to a cell unit obtained by the present method.

[0012] According to another aspect, the invention relates to a high-temperature electrochemical cell unit comprising, in order according to its thickness, a hydrogen electrode, a solid electrolyte, an oxygen electrode and a seal being arranged on the solid electrolyte and forming a frame around the oxygen electrode, the seal being capable of taking a first state during its positioning and a second state after a treatment which is more gas-tight and / or advantageously more adherent to the second face of the solid electrolyte than in its first state.

[0013] According to another aspect, the invention relates to a stack of several cell units obtained by the present method.

[0014] BRIEF DESCRIPTION OF THE FIGURES

[0015] The aims, objects, as well as the characteristics and advantages of the invention will emerge more clearly from the detailed description of an embodiment thereof which is illustrated by the following accompanying drawings in which:

[0016] Figure 1A shows a solid electrolyte of a cell unit comprising a seal according to the invention in top view.

[0017] Figure 1B shows a view along section AA of the solid electrolyte of the cell unit comprising a seal according to Figure 1A.

[0018] Figure 2 shows a longitudinal sectional view of a cell unit according to the invention with the seal secured to the solid electrolyte.

[0019] Figure 3 shows a longitudinal sectional view of a cell unit comprising an interconnector, the seal being secured to the solid electrolyte and to the interconnector.

[0020] Figure 4 shows a longitudinal sectional view of a cell unit comprising an interconnector and a contact material, the seal being secured to the solid electrolyte and the interconnector.

[0021] Figure 5 represents a scanning electron microscopy view of a polished section of a cell unit obtained by the method of the invention - BEC 20.0 Kv WD 12mm P. CH X150. The drawings are given as examples and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily on the scale of practical applications. In particular, the thicknesses of the layers are not representative of reality.

[0022] DETAILED DESCRIPTION OF THE INVENTION

[0023] Before commencing a detailed review of embodiments of the invention, optional features which may optionally be used in combination or alternatively are set out below:

[0024] - According to one example, the positioning of the seal is carried out to form a frame at the edge of the second face of the solid electrolyte;

[0025] - According to one example, the formation of the oxygen electrode is carried out after the treatment of the seal;

[0026] - According to one example, the manufacturing method comprises forming a contact layer opposite the second face of the oxygen electrode framed by the seal;

[0027] - According to one example, the treatment of the seal is chosen from at least one of a heat treatment, thermocompression, or the addition of a solvent;

[0028] - According to one example, the manufacturing method comprises the positioning of the seal by strip casting;

[0029] - According to one example, the manufacturing method comprises a heat pretreatment of the seal preferably before the treatment of the seal, advantageously to debind the seal;

[0030] - According to one example, the method comprises a step of positioning an interconnector with respect to the second face of the oxygen electrode, before or after the treatment of the seal;

[0031] - According to one example, the seal has a coefficient of expansion between 9 and 17 .10-6 K-1;

[0032] - In one example, the seal has a glass transition temperature lower than the operating temperature of the cell unit.

[0033] - According to one example, the electrochemical cell unit is not arranged in a fuel cell;

[0034] - According to one example, the cell unit comprises an interconnector arranged on the oxygen electrode side and secured to the seal in its second state. Vertical means that which is directed along the thickness of the cell unit or stack, i.e., along the main direction of extension of the cell unit or stack, and horizontal means that which is perpendicular to the vertical. The top and bottom are vertically opposed.

[0035] Transverse means a direction perpendicular to a longitudinal direction. The longitudinal direction is understood as the thickness of the cell unit or stack. A transverse section is a section perpendicular to the longitudinal axis. A transverse section is a section perpendicular to the thickness of the cell unit or stack. A longitudinal section is a section parallel to the thickness of the cell unit or stack.

[0036] A parameter "substantially equal / greater / less than" or "of the order of" a given value means that this parameter is equal / greater / less than the given value, to within plus or minus 10%, or even plus or minus 5%, of this value.

[0037] 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).

[0038] The word "dielectric" refers to a material whose electrical conductivity is low enough in the given application to serve as an insulator.

[0039] An element “based on” a material A means an element comprising this material A only or this material A and possibly other materials.

[0040] The terms "first", "second" and "third", "additional" etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

[0041] The term "upper" used in particular to describe a face of a layer is used here only to designate the first of the two faces of the layer (the other being the lower face), without making any assumption about the relative position of the faces, in a vertical direction. The upper face could thus also have been called the front face, as opposed to a rear face.

[0042] The shapes or dimensions given for certain components of the present invention are always only indicative and are understood as including substantially equivalent shapes and dimensions.

[0043] It is specified that in the context of the present invention, the term "on", "overcomes", "covers", "above" or "underlying" or "below" or their equivalents do not necessarily mean "in contact with". For example, the deposition of a first layer on 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.

[0044] Binder or additive means electrically conductive materials or materials that ensure the cohesion of the active phase.

[0045] The present invention relates to a high temperature electrochemical cell unit 100. The cell unit 100 comprises a superposition of layers including an anode, a cathode and a solid electrolyte 102 arranged between the anode and the cathode. The cathode is preferably a hydrogen electrode 101 and the anode is preferably an oxygen electrode 103.

[0046] According to one possibility, the cell unit 100 has a support electrode and it is the hydrogen electrode 101 which preferentially ensures the mechanical maintenance of the cell unit 100. According to this possibility, the hydrogen electrode 101 is a layer with a thickness of the order of 400 μm.

[0047] For example, the hydrogen electrode 101 is a cermet and is composed of a mixture of ionic conductive oxide and a catalyst metal, most often nickel. This metal in fact has a strong catalytic activity with respect to the reduction of water and therefore the production of hydrogen.

[0048] The superposition of the layers of the cell unit 100 is done according to the thickness Ep1 of the hydrogen electrode layer 101.

[0049] The hydrogen electrode 101 comprises a first face 1011 and a second face 1012, opposite each other and preferably parallel. The first face 1011 and the second face 1012 extend along a longitudinal plane, perpendicular to the thickness of the superposition. Preferably, the first face 1011 and the second face 1012 are of identical dimensions. 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 rate of 8 mol%). The mixtures conventionally used have a content of approximately 50 to 70% by mass of NiO.

[0050] The cell unit 100 comprises, opposite the first face 1011 of the hydrogen electrode 101, a solid electrolyte 102. Preferably, the solid electrolyte 102 is a solid oxide electrolyte. The solid electrolyte 102 is a layer comprising a first face 1021 and a second face 1022, opposite each other and preferably parallel. The first face 1021 and the second face 1022 extend along a longitudinal plane. Preferably, the first face 1021 and the second face 1022 are of identical dimensions. Preferably, the first face 1021 and the second face 1022 of the solid electrolyte 102 are of dimensions substantially equivalent to the second face 1012 of the hydrogen electrode 101. By way of non-limiting example, the conventional electrolyte materials are zirconium oxides, doped with yttrium or scandium oxides at a level of 3 to 10 mol%.

[0051] The cell unit 100 comprises, opposite the second face 1022 of the solid electrolyte 102, an oxygen electrode 103. The oxygen electrode 103 has a first face 1031 and a second face 1032, opposite each other and preferably parallel. The first face 1031 and the second face 1032 extend along a longitudinal plane. Preferably, the first face 1031 and the second face 1032 are of identical dimensions. Preferably, the first face 1031 and the second face 1032 of the oxygen electrode 103 are of smaller dimensions than those of the second face 1022 of the solid electrolyte 102. By way of non-limiting example, the oxygen electrode materials are conventionally of perovskite structure (ABO3). One of the most widely used materials currently is (LaSr)(CoFe)O3.

[0052] Preferably, the oxygen electrode 103 is configured so as not to cover the entire second face 1022 of the solid electrolyte. Preferably, the oxygen electrode leaves the edge of the second face 1022 of the solid electrolyte 102 free so as to form a frame without an oxygen electrode 103.

[0053] According to one possibility, the cell unit 100 comprises a barrier layer 105 arranged between the solid electrolyte 102 and the oxygen electrode 103. More specifically, the barrier layer 105 is arranged between the second face 1022 of the solid electrolyte and the first face 1031 of the oxygen electrode 103. The barrier layer has a first face 1051 and a second face 1052 opposite each other and preferably parallel. The first face 1051 and the second face 1052 extend along a longitudinal plane. Preferably, the first face 1051 and the second face 1052 are of identical dimensions. Preferably, the first face 1051 and the second face 1052 of the barrier layer 105 are of identical dimensions to the second face 1032 of the oxygen electrode 103.

[0054] The barrier layer 105 is intended to limit the reactivity of the oxygen electrode material with the electrolyte material, particularly during heat treatment steps. Typically, without this layer, for temperatures above 1250°C, deleterious insulating phases can form (for example LaSrZrCh).

[0055] According to one possibility, the cell unit 100 comprises a contact layer 106. The contact layer 106 is intended to optimize the circulation and diffusion of gases towards the hydrogen electrode 101 or from the oxygen electrode 103. For example, the cell unit 100 comprises a contact layer 106a arranged opposite the first face 1011 of the hydrogen electrode 101. Preferably, the contact layer 106a has a surface identical to that of the hydrogen electrode 101. For example, the cell unit 100 comprises a contact layer 106b arranged opposite the second face 1032 of the oxygen electrode 103. Preferably, the contact layer 106b has a surface identical to that of the oxygen electrode 103.

[0056] The contact layer 106b is intended to limit the contact resistance between the interconnector and the cell unit.

[0057] According to one embodiment, the cell unit comprises a layer of contact material 108 comprising longitudinal gas supply channels. This layer 108 is advantageously intended to facilitate the evacuation of gas from the oxygen electrode to the interconnector 107.

[0058] According to the invention, the cell unit 100 comprises a seal 104 arranged on the solid electrolyte 102, more precisely in contact with the second face 1022 of the solid electrolyte 102. Advantageously, the seal 104 forms a frame at the edge of the second face 1021 of the solid electrolyte 102. The seal 104 is advantageously continuous over the entire edge of the second face 1021 of the solid electrolyte 102. Preferably, the seal 104 is arranged on the second face 1021 of the solid electrolyte 102 in line with its thickness so as to optimize the surface of the electrolyte 102 framed by the seal 104. In this way, the sealing of the oxygen compartment with respect to the hydrogen compartment is performed while maintaining a satisfactory surface area for the oxygen electrode 103.

[0059] The oxygen electrode 103 is advantageously arranged in the frame formed by the seal 104. Advantageously, the seal 104 is advantageously in contact with the thickness of the oxygen electrode 103. In the case where the cell unit 100 comprises a barrier layer 105 and / or a contact layer 106b and / or a layer of material 108, the seal 104 is in contact with their thickness.

[0060] The seal 104 has a first face 1041 and a second face 1042, opposite each other and preferably parallel. The first face 1041 is advantageously in contact with the second face 1022 of the solid electrolyte 102.

[0061] According to a preferred embodiment, the seal 104 has a width that is smaller than its thickness. More precisely, the width of the first face 1041 and the width of the second face 1042 are smaller than the thickness of the seal 104. The seal 104 may take the form of a parallelogram, preferably substantially a rectangle.

[0062] The cell unit 100 according to the invention is characterized in that the seal 104 is capable of ensuring the desired seal for a cell unit 100 intended to be stacked with other cell units to form a fuel cell of the SOFC or SOEC type. For this purpose, the seal is advantageously said to be functional. Preferably, the seal 104 is said to be functional for a cell unit 100 without another cell unit 100, that is to say without being integrated into a stack of cell units of the battery type also called a stack.

[0063] The seal 104 is advantageously deposited by strip casting on the solid electrolyte 102. The seal 104 thus forms a strip intended to surround the oxygen electrode 103.

[0064] The seal 104 is advantageously configured to be compatible with the materials of the cell unit 100. Advantageously, the seal 104 has a coefficient of expansion between 9 and 17.10-6 K-1. The seal 104 preferably has a glass transition temperature lower than the operating temperature of the cell unit 100, for example lower than 700°C. Preferably, the seal 104 does not form a secondary phase that is harmful to the cell unit 100. For example, the seal 104 comprises a mixture of solvent and / or plasticizer and / or binder and / or dispersant and a filler preferably formed by glass powders and / or glass ceramic.

[0065] According to one embodiment, the seal 104 is capable of taking a first state in which the seal 104 is placed on the solid electrolyte 102, in particular by casting, and a second state in which the seal 104 is preferably more gas-tight and / or preferably more adherent to the solid electrolyte 102 than in the first state. Advantageously, in its second state, the seal 104 has a leak rate of less than 10' 3 mbar.l / s under air with an overpressure of 100mbar. Preferably, in its first state, the seal 104 has a higher leak rate than in its second state.

[0066] The seal 104 is transformed from the first state to the second state by a treatment applied to the seal 104 and thus to the already formed elements of the cell unit 100 during the treatment.

[0067] The treatment may be a heat treatment and / or a thermocompression treatment and / or a solvent addition treatment. The treatment is intended to modify the state of the seal 104 so that it passes from the first state to the second state.

[0068] According to one embodiment, the seal 104 has a thickness at least equal to the thickness of the oxygen electrode 103. Preferably, the seal 104 has a thickness at least equal to the sum of the thickness of the oxygen electrode 103 and the additional layers placed between the second face 1022 of the solid electrolyte 102 and the first face 1031 of the oxygen electrode 103 and opposite the second face 1032 of the oxygen electrode 103.

[0069] The seal 104 has a difference in thickness between its first state and its second state. The loss in thickness between the first state and the second state of the seal 104 corresponds substantially to the percentage of the seal 104 that is not the filler. For example, a seal 104 that has a filler rate of 80% by mass will see a loss in thickness between its first state and its second state of the order of 15 to 20%.

[0070] Preferably, the seal 104 has a width of 5 mm to 15 mm.

[0071] According to one possibility, the cell unit 100 comprises an interconnector 107 arranged facing the second face 1032 of the oxygen electrode 103. Preferably, the interconnector 107 has a surface facing the oxygen electrode 103 which is greater than the second face 1032 of the oxygen electrode 103 and / or greater than the second face 1022 of the solid electrolyte 102.

[0072] Advantageously, the seal 104 ensures a seal with the interconnector 107. More preferably, in its second state the seal ensures gas-tightness and / or adhesion with the interconnector 107 and in particular its first face 1071. More precisely, the interconnector 107 comprises a first face 1071 facing the oxygen electrode 103 and coming into contact with the seal 104, more precisely in contact with the second face 1042 of the seal 104. This arrangement makes it possible to make the interconnector 107 integral with the solid electrolyte 102 by means of the seal 104. The seal of the cell unit 100 is thus formed independently of, and before, the stacking of several cell units in the form of a battery.

[0073] According to one aspect, the invention relates to a method of manufacturing a cell unit 100 as described above.

[0074] The method comprises a step of positioning the seal 104 on the solid electrolyte 102, more precisely on its second face 1022.

[0075] Advantageously, the positioning of the seal 104 is achieved by casting the seal 104 in strip form. Preferably, the seal 104 is cast in its first state. The casting is carried out, for example, by a shoe of a height adequate to the thickness of the seal in its first state. The speed of advance of the shoe is also adapted to the properties of the seal 104 in its first state. Alternatively, the seal can be cast in strip form outside the cell unit and then the cut strips are assembled to form a frame on the solid electrolyte 102.

[0076] According to one embodiment, the method according to the invention comprises, after the step of positioning the seal 104, possibly a step of pretreating the seal 104. This pretreatment step is intended to advantageously debind the seal 104, i.e. remove the binder. For example, the pretreatment is a heat pretreatment. The temperature of the heat pretreatment is advantageously between 20°C and 900°C depending on the morphology of the seal 104, in particular the desired glass or glass-ceramic (just debinded, completely formed, etc.). Preferably, the heat pretreatment step is carried out at temperatures lower than the glass transition temperature of the glass or glass-ceramic used, as is, for example, between 200°C and 500°C.This pretreatment step allows the proper evacuation of organic matter from the seal 104, and improves the final quality of said seal by limiting the presence of bubbles / residual gases.

[0077] The method according to the invention comprises a step of treating the seal 104. This treatment step is carried out either directly following the positioning of the sealing seal 104, or follows a pretreatment step described above.

[0078] The treatment of the seal 104 is intended to change the seal 104 from its first state to its second state. The treatment may be a heat treatment, in particular by placing the cell unit 100 comprising the seal 104 in an oven and / or thermocompression of the seal 104 and / or the addition of a solvent at least on one face of the seal 104.

[0079] For example, a heat treatment is carried out by placing the cell unit 100 in an oven at a temperature between 50 and 100°C. For example, a thermocompression treatment is a treatment consisting of applying compression, for example between 1000 and 3000 psi, to the seal 104 and a temperature between 50 and 100°C. For example, the treatment by adding solvent makes it possible to dissolve the binder present in the seal 104. The added solvent is for example chosen from water, alcohol or a mixture thereof.

[0080] According to one possibility, in particular when the thickness of the seal 104 is greater than 500 μm, the method comprises a first step of positioning the seal 104, for example with a maximum dimension of 200 μm, then a first step of treatment, preferably by thermocompression, then a second step of positioning the seal 104 in a first state on the seal 104 in a second state, then a second step of treatment, for example either by thermocompression, or heat, or by solvent. This possibility makes it possible to obtain a seal of different dimensions or even geometries depending on the needs, the interconnectors, etc., without needing to modify the method of depositing the seal 104.

[0081] Advantageously, the method comprises a step of placing an interconnector 107. The interconnector 107 can be positioned before the pretreatment step or preferably, the interconnector 107 is positioned after the pretreatment step. In the latter case, the interconnector 107 can optionally be positioned after the step of treating the seal which is then in its second state or advantageously, the interconnector 107 is arranged on the seal 104 before the treatment step, that is to say preferably while the seal 104 is not yet in its second state to allow the interconnector 107 to be positioned, for example while the seal 104 has greater flexibility than in its second state.

[0082] According to one embodiment, the method comprises, before the step of placing an interconnector 107, a step of placing flexibility elements above the oxygen electrode 103 such as, for example, a contact layer 106b and / or contact materials 108 allowing the formation of gas channels and facilitating the electrical contact and diffusion of the gas on the side of the 2 oxygen electrodes 103.

[0083] According to one possibility, the pretreatment step of the seal 104 is carried out on a half-cell unit 100, i.e. a cell unit 100 comprising the hydrogen electrode 101 and the solid electrolyte 102, but in particular not yet the oxygen electrode 103. According to this possibility, the half-cell 100 is completed by forming at least the oxygen electrode 103 and possibly also the barrier layer 105 and / or the contact layer 106b.

[0084] According to one possibility, the formation of these layers is carried out after the step of treating the seal 104.

[0085] Alternatively, this step of processing the seal 104 is performed on a cell unit 100, i.e. a cell unit in which the oxygen electrode 103 is already deposited. Preferably, all of the layers constituting the cell unit 100, with the exception of the interconnectors, are already deposited.

[0086] According to one embodiment, the method comprises, after the step of treating the seal, a step of stacking several cell units on top of each other to form a fuel cell. More specifically, this stacking step is carried out after the step of treating the seal and after the step of placing the interconnector 107.

[0087] Example 1 - method of manufacturing a cell according to the invention

[0088] A strip-cast glass-ceramic type gasket 104 is positioned on a half-unit of the electrochemical cell and secured by the addition of solvent, here ethanol.

[0089] The second face of the solid electrolyte 102 on which the seal 104 is placed is first carefully cleaned with ethanol. The half-cell unit 100 comprising the seal 104 is heat-treated at 860°C for one hour. It is observed by scanning electron microscopy BEC 20.0 Kv WD 12mm P. C HV X150 of a polished section obtained that the interface between the seal 104 and the solid electrolyte 102 is without defect. The seal 104 appears perfectly adherent. The interface between the seal 104 and the electrolyte is indeed continuous, without delamination. The sealing function is therefore obtained thanks to the invention, the sealing function being integrated into the cell unit 100 and the sealed cell unit 100 is ready to be integrated into a stack.

[0090] Example 2 - Process for preparing a seal

[0091] The seal 104 is prepared from a binder solution and a slip.

[0092] Preparation of the binder solution:

[0093] - In a suitable plastic container, add 109.5g of toluene and 27.2g of ethanol,

[0094] - Add the PVB binder mixture for PolyVinyl Butyral, advantageously, two chain lengths are used, B30HH and B60HH from the supplier MOWITAL, i.e. 43.3g of B30HH and 11.1g of B60HH previously mixed,

[0095] - Stir with a bottle turner at 45 rpm until ready to use. Preparation of the slip:

[0096] - In a zirconia bowl of a planetary mixer (Fritsch brand pulverisette used): add 59g of toluene, 14.5g of ethanol, 14.8g of dibutylsebacate. Add 3 zirconia balls of diameter 15mm,

[0097] - Mix for 10 minutes at 100 rpm. Add 190g of glass-ceramic powder (in our case reference G018-311 from the Schott brand). Add 7 zirconia beads with a diameter of 15mm and 38 beads with a diameter of 10mm,

[0098] - Mix for 1 hour in the planetary mill at 270 rpm,

[0099] - Leave to cool for 30 minutes, then add 130g of the binder solution previously prepared and described,

[0100] - Add 10 zirconia beads with a diameter of 15mm and 38 beads with a diameter of 10mm,

[0101] - Mix for 1 hour at 270 rpm in the grinder. Leave to cool for 105 minutes,

[0102] - Add 3.5g of KM6103 dispersant (Zschimmer and Schwarz). Mix for 1 hour at 270 rpm, then 16 hours at 120 rpm in the grinder. Leave to de-air for 2 days in a bottle turner at 45 rpm.

[0103] Positioning the seal: Once deaerated, for casting the strip, an example thickness (250 pm after drying) was carried out. For this, the height of the casting shoe was set at 1200 pm and the film advance speed set at 141 cm / minute.

[0104] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention. LIST OF REFERENCES

[0105] 100. Cell Unit

[0106] 101. Hydrogen electrode

[0107] 1011. First side

[0108] 1012. Second side

[0109] 102. Solid electrolyte

[0110] 1021. First side

[0111] 1022. Second side

[0112] 103. Oxygen electrode

[0113] 1031. First side

[0114] 1032. Second side

[0115] 104. Sealing gasket

[0116] 105. Barrier layer

[0117] 106. a, b Contact layer

[0118] 107. Interconnector

[0119] 1071. First side

[0120] 1072. Second side

[0121] 108. Contact material

[0122] Ep. Thickness of the cell unit

[0123] Ep1. Thickness of the hydrogen electrode

Claims

CLAIMS 1. A method of manufacturing an electrochemical cell unit (100) comprising in order according to its thickness a hydrogen electrode (101) comprising a first face (1011) and a second face (1012), opposite each other and a solid electrolyte (102) comprising a first face (1021) and a second face (1022), opposite each other, the first face (1021) of the solid electrolyte (102) facing the second face (1012) of the hydrogen electrode (101), characterized in that the method comprising the following steps: • positioning a seal (104) in a first state in the form of a strip on the second face (1022) of the solid electrolyte (102) at the edge of said second face (1022), then • treatment of the seal (104) intended to bring the seal (104) into a second so-called functional state, more gas-tight than the first state, the treatment being carried out before a possible step of stacking in the form of a pile, • formation, opposite the second face (1022) of the solid electrolyte (102), of an oxygen electrode (103) comprising a first face (1031) and a second face (1032), opposite one another, the seal (104) forming a frame around the oxygen electrode (103).

2. Manufacturing method according to the preceding claim in which the positioning of the sealing gasket (104) is carried out to form a frame at the edge of the second face (1022) of the solid electrolyte (102).

3. Manufacturing method according to any one of the preceding claims wherein the formation of the oxygen electrode (103) is carried out after the treatment of the seal (104).

4. Manufacturing method according to any one of the preceding claims comprising the formation of a contact layer (106b) facing the second face (1032) of the oxygen electrode (103) framed by the seal (104).

5. Manufacturing method according to any one of the preceding claims in which the treatment of the seal (104) is chosen from at least one of a heat treatment, thermocompression, or addition of a solvent.

6. Manufacturing method according to any one of the preceding claims in which the positioning of the sealing gasket (104) is done by strip casting.

7. A manufacturing method according to any preceding claim comprising heat pretreatment of the seal (104) prior to treatment of the seal (104).

8. Manufacturing method according to any one of the preceding claims comprising a step of positioning an interconnector (107) opposite the second face (1032) of the oxygen electrode (103), preferably after treatment of the seal (104).

9. Manufacturing method according to any one of the preceding claims in which the sealing gasket (104) has a coefficient of expansion between 9 and 17.10' 6 K-1.

10. A manufacturing method according to any preceding claim wherein the seal (104) has a glass transition temperature lower than the operating temperature of the cell unit (100).

11. High temperature electrochemical cell unit (100) comprising in order according to its thickness a hydrogen electrode (101), a solid electrolyte (102), an oxygen electrode (103) and a seal (104) being arranged on the solid electrolyte (102) and forming a frame around the oxygen electrode (103), characterized in that the seal (104) is capable of taking a first state during its positioning and a second state after treatment in which it is more gas-tight than in its first state.

12. Electrochemical cell unit (100) according to the preceding claim comprising an interconnector (107) arranged on the side of the oxygen electrode (103) and secured to the seal (104) in its second state.

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