Electrolysis or co-electrolysis cell (SOEC) or fuel cell (SOFC), having electrochemical cell stack incorporated with mechanical reinforcement element with temperature variable stiffness

Abstract

To provide an improved electrochemical device having an electrochemical cell stack.SOLUTION: An electrochemical device of the present invention is formed by an assembly of conventional stacking in which an electrochemical cell and an electrical / fluid connector are alternately stacked. At least one mechanical reinforcement element is arranged on each stack for receiving a bending force which tends to occur during stacking between initial thermo-mechanical processing steps.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to the field of solid oxide fuel cells (SOFCs), high-temperature electrolysis of water (HTE), or similarly high-temperature steam electrolysis (HTSE) with solid oxides (SOEC for solid oxide electrolyzer cells), and the field of high-temperature co-electrolysis of water with other gases selected from carbon dioxide CO2 and nitrogen dioxide NO2.

[0002] More particularly, the present invention relates to the realization of an electrochemical device that constitutes a reactor for high-temperature electrolysis (HTE) or co-electrolysis of water, SOEC-type high-temperature electrolysis (HTE) or co-electrolysis, or SOFC-type fuel cell high-temperature electrolysis (HTE) or co-electrolysis, having a stack of basic electrochemical cells.

[0003] The present invention is most directed to improving the assembly and operation of such devices and the like.

[0004] Although the present invention is mainly described with reference to the application of high-temperature electrolysis of water, it is also fully applicable to the co-electrolysis of water and other gases selected from, for example, carbon dioxide (CO2) in SOFC-type fuel cells.

[0005] Alternatively, the present invention is applicable to SOFC-type fuel cells that use hydrogen, hydrocarbons such as methane (CH4), or any other fuel such as NH3 as the fuel.

Background Art

[0006] An SOFC type fuel cell or an HTE electrolyzer is an electrochemical device composed of a stack of basic components, each comprising a solid oxide electrochemical cell consisting of an anode / electrolyte / cathode, which are three layers stacked on top of each other, and an interconnecting plate made of a metal alloy, also called a bipolar plate or an interconnect. The function of the interconnect is to pass an electric current and circulate gases in the vicinity of each cell (in the HTE electrolyzer, the injected steam, as well as the extracted hydrogen and oxygen, and in the SOFC cell, the injected air and hydrogen, and the extracted water), and to separate them into the anode chamber and the cathode chamber, which are the gas circulation chambers on the anode side and the cathode side of the cell, respectively.

[0007] To perform the above high-temperature electrolysis (HTE), typically between 600 °C and 950 °C, steam (H2O) is injected into the cathode chamber. Under the effect of the electric current applied to the cell, water molecules in the form of steam dissociate at the interface between the hydrogen electrode (cathode) and the electrolyte, and this dissociation produces gaseous dihydrogen (H2) and oxygen ions. Dihydrogen is recovered and discharged at the outlet of the hydrogen chamber. Oxygen ions (O2 - ) move through the electrolyte and recombine into diatomic oxygen at the interface between the electrolyte and the oxygen electrode (anode).

[0008] To ensure the operation of the SOFC type fuel cell, air (oxygen) is injected into the cathode chamber and hydrogen is injected into the anode chamber. Hydrogen (H2) is converted into H + ions, releasing electrons, which are captured by the anode. H + ions arrive at the cathode, where they combine with O2 - ions formed from oxygen derived from the air to form water. The movement of H + ions and electrons to the cathode will result in the generation of a continuous current based on hydrogen.

[0009] In order to increase the flow of hydrogen and oxygen generated in the case of HTE electrolysis, or to increase the power supplied in the case of a SOFC type fuel cell, it is a known practice to stack a plurality of basic electrochemical cells one after another with separation by interconnecting parts. The assembly is positioned between two end connection plates that support the electrical supply and the gas supply / recapture of the electrolyzer (electrolysis reactor) or the SOFC type fuel cell.

[0010] Furthermore, in order to improve the quality of the electrical contact made between the interconnecting part and the electrode, and thus, to improve the performance of the aforementioned electrochemical device, electrical contact elements are individually interposed and arranged on the electrodes. In electrochemical devices, nickel grids have been conventionally used for contact with the hydrogen electrode (cathode in the HTE reactor, anode in the SOFC type fuel cell) in order to produce satisfactory results at low cost.

[0011] Throughout the preparation of the electrochemical device, each layer and each stage of the stack must be positioned very precisely and this position must be maintained.

[0012] Before operating the aforementioned electrochemical device, it is necessary to expose the stack of the electrochemical device to a heat treatment step called at least one reduction step in order to bring the electrochemical cells into their reduced form rather than their oxidized form as in their initial state.

[0013] This reduction step can be a thermomechanical cycle under gas, that is, under a reducing gas for the hydrogen electrode and air or a neutral gas for the oxygen electrode.

[0014] One specific heat treatment step is described in patent EP2870650B1.

[0015] The stacks used heretofore generally use seals that must ensure no leakage between two different adjacent gas circulation chambers, namely an anode chamber and a cathode chamber, in each of their stages. Advantageous seals are described in patent EP3078071B1. These seals have the specific feature that they require thermal conditioning in which the seal is compressed therebetween.

[0016] Contact elements such as the layers described in patent application EP2900846A1, or nickel grids, will also be compressed during thermal conditioning and during the operation of the electrochemical device, which ensures accurate installation. The elements serving as contact elements in the hydrogen chamber are also compressed. In other words, during the thermal conditioning step, the stack of the aforementioned electrochemical device is typically compressed by several centimeters. Currently, the compression is carried out accurately.

[0017] However, in a specific SOEC / SOFC stack, the inventor observed harmful deformations during the heat treatment step before operation. These deformations reduce the contact area between the electrochemical cell and the electrical contact element.

[0018] This undesirable situation is shown in FIGS. 1 and 2 in an electrochemical device 1 comprising a stack of a solid oxide-based SOEC / SOFC type electrochemical cell 2 and an electro-fluidic interconnect 3 made of a gas-tight and electronically conductive material for supplying or recovering current to or from the cell and for supplying, recovering, and circulating gas across each electrode of each electrochemical cell. Each electrochemical cell consists of a first electrode forming a cathode, a second electrode forming an anode, and an electrolyte interposed between the two electrodes.

[0019] For clarity, in these FIGS. 1 and 2, a single electrochemical cell 2 is shown as being arranged between two interconnects 3.

[0020] The first electrical contact element 4 is arranged in contact with the electrode of the battery 2 facing the interconnection 3. This element can take the form of a nickel lattice and preferably has notches as described in patent application FR2213927 and possibly incorporates glass in the form of one or more beads for guiding gas as described in patent EP3156721B1.

[0021] A second electrical contact element 5 is arranged in contact with another interconnection 3 facing the other electrode of the battery 2. This element can be a conductive ceramic layer, in particular a grooved layer, and can be a strip of strontium-doped lanthanum manganite (SLM) that has been pre-cut and is directly joined or hot-pressed to the interconnection 3. The joining can be done without residues as described in patent application WO2022 / 234214. The SLM strip can also be joined by hot-pressing onto the surface of the interconnection 3 as described in EP2900846B1.

[0022] As shown at the end of the stack, an electrical contact element 5, in particular the same element that is in contact with the interconnection, can be fixed to the inner surface of the end plate 6 of the stack 1.

[0023] A seal 7, preferably made of glass-ceramic, is installed around the battery 2 and the gas passages and is brought into contact with the battery 2 or one and the other of the electrical contact elements 4, 5. The seal 7 between two adjacent interconnections 3 in the stack can be made of an electrically insulating material and can be supported by a leak-proof frame 8 preferably made of mica.

[0024] In this configuration, the metal elements (end plate 6, interconnections 3) are initially located at the seal 7 as shown in FIG. 1.

[0025] Stack 1 is clamped cold between a support point P and an axial load C, and this clamping is carried out in the vertical direction. During the first temperature rise, while the mechanical strength of the metal elements 6 and 3 decreases, the mechanical strength of the seal 7 does not change, typically up to 650 °C and even up to 700 °C if these seals are made of glass-ceramic.

[0026] However, the bending load applied to the metal elements 3, 6 causes irreversible deformation of said elements (Figure 2), which is detrimental to subsequent electrical contact. The reason is that, as schematically shown, the flat surfaces of the metal elements, which ideally should be in direct contact over their entire surface area, no longer are.

Prior Art Documents

Patent Documents

[0027]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Summary of the Invention

Problems to be Solved by the Invention

[0028] Therefore, there is a need to further improve an electrochemical device comprising a stack of electrochemical cells forming a SOEC electrolysis reactor or a SOFC fuel cell, in particular to prevent the undesirable irreversible deformation of the electrical contact elements in the stack that may occur during the primary stage of the first temperature rise during the thermal conditioning before the first operating cycle.

Means for Solving the Problem

[0029] For this purpose, a first subject of the present invention is an electrochemical device intended to operate at high temperature, which is a SOEC electrolysis or co-electrolysis reactor or a SOFC fuel cell, comprising: - a stack of SOEC / SOFC-based electrochemical cells and electrical fluid interconnects individually arranged on both sides of each electrochemical cell, each interconnect comprising at least one component made of an electronically conductive and gas-tight material for supplying or recovering current to the cell and for supplying, recovering and circulating gas across each electrode of each electrochemical cell; - two plates arranged at the ends of the stack and called end plates; - a plurality of electrical contact elements each arranged in contact with one face of an end plate, in contact with an electrode of an electrochemical cell or in contact with a face of an interconnect; - a plurality of seals each arranged around each through-hole to ensure sealing around each gas inlet / outlet in the stack; - a plurality of mechanical reinforcement elements each arranged in contact with one face of an end plate, in contact with an electrode of an electrochemical cell or in contact with a face of an interconnect, made of an electrically insulating material that can vary as a function of temperature and exhibits a rigidity substantially equal to that of the seals so that, during the first rise in the temperature of the device before operation of the device, the reinforcement elements soften and then melt simultaneously with the seals to limit the bending of the end plates and the interconnects; An electrochemical device comprising.

[0030] The mechanical reinforcement elements preferably comprise the same constituent material as the seal, preferably a glass ceramic.

[0031] The mechanical reinforcement elements are advantageously in the form of beads and preferably are closed in themselves and / or in the form of solid pads.

[0032] Furthermore, advantageously, at least a part of the mechanical reinforcement elements is arranged at the center of the surface of the end plate, at the center of the electrodes of the electrochemical cell or at the center of the surface of the interconnect. When at least a part of the mechanical reinforcement elements is at the center of the stack components, the position where the force is received by the reinforcement elements can reduce the bending torque to a quarter because the bending torque depends on the square of the length. The mechanical reinforcement elements according to the invention can be a support at a point at the center of the component or in any other geometric shape that reduces the bending torque.

[0033] The material used for the inclusion for receiving the force is advantageously made of the same material as the seal such that a change in rigidity occurs simultaneously when the softening / melting temperature is reached.

[0034] The surface area of the mechanical reinforcement elements is preferably between 0.1 cm 2 and 10 cm 2 and more preferably 0.5 cm 2 is.

[0035] According to a first advantageous variant embodiment, the electrical contact element preferably comprises at least one conductive grid made of gold.

[0036] The grid made of gold can have a mesh number of 100 to 3600 meshes / cm 2 and a surface area between 0.5 cm 2 and 5 cm 2 and preferably 2 cm 2It is of such a degree. A nickel lattice can also be expected. In that case, attention is paid to providing a sealing means around the lattice to prevent oxidation of the lattice. A copper lattice can also be expected. A lattice of conductive ceramic can also be expected. A lattice of ferritic steel, preferably made from ferritic steel containing about 20% chromium and preferably made from CROFER® or K41 (441 steel), can function when in the form of a lattice. The reason is that these high-Cr-containing steels have good corrosion resistance and are good conductors.

[0037] A lattice made of a noble metal such as platinum can also be expected.

[0038] The number of lattices per surface of the insertion plate can be between 1 and 10, preferably 5. In the case of a single lattice, the amount of material is limited, but the mechanical balance in the stack may not be optimal. In the case of a number of 10 lattices, the mechanical balance is ensured, but the amount of material used can be considerable.

[0039] The surface area of the lattice is preferably about 0.5 cm 2 for a sheet surface area of the order of, preferably from 0.5 cm 2 to 5 cm 2 and preferably of the order of 2 cm 2 or so.

[0040] More preferably, one or more lattices are directly welded to the surface of the interconnecting part and / or the end plate. The welding can be of the spot type.

[0041] According to one advantageous variant embodiment, the mechanical reinforcement element is in the form of a solid pad arranged in a notch made in the center of the lattice.

[0042] According to one advantageous variant embodiment, a number of 5 lattices, distributed in a square or rectangle and one being at the center of the square or rectangle and in contact with one battery electrode, are provided.

[0043] According to this embodiment and the advantageous configuration, the mechanical reinforcement element is in the form of a closed bead in itself and surrounds the grid at the center of a square or rectangle.

[0044] According to a second advantageous variant embodiment, the electrical contact element comprises at least one layer of a conductive ceramic material.

[0045] According to this second variant, the conductive ceramic material is preferably - La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O3 (LSCF), - La 0.8 Sr 0.2 Cu 0.9 Fe 0.1 O 2.5 (LSCuF), - La 0.7 Sr 0.3 CoO3 (LSC), - Sm 0.5 Sr 0.5 CoO3 (SSC), - SmBa 0.5 Sr 0.5 Co2O5 (SBSC), - GdSrCo2O5 (GSC), - La 0.65 Sr 0.3 MnO3 (LSM), - LaBaCo2O5 (LBC), - YBaCo2O5 (YBC), - Nd 1.8 Ce 0.2 CuO4 (NCC), - La 0.8 Sr 0.2 Co 0.3 Mn 0.1 Fe 0.6 O3 (LSCMF), - La 0.98 Ni 0.6 Fe 0.4 O3 (LNF), - La 1.2 Sr0.8 NiO4 (LSN), - La 0.7 Sr 0.3 FeO3 (LSF), - La2Ni 0.6 Cu 0.4 O4 (LNC) is selected from the group consisting of.

[0046] With further advantages, the conductive ceramic material is selected from the group consisting of LSM, LSC, LNF, and LSCF.

[0047] The layer of the conductive ceramic material is preferably hollowed out at least in part of its thickness. The hollow can constitute grooves, pores, or any other form. The hollowing out of the contact layer, more specifically grooving, increases the stress for a given compressive force, and thereby further compresses the layer, making it possible to better correct surface defects. In other words, grooving the contact layer improves the contact layer's ability to withstand compression. Conversely, a solid contact layer promotes electrical contact due to a larger surface area for current passage.

[0048] Advantageously, the layer of the conductive ceramic material is preferably joined by hot pressing, using an adhesive, or by hot pressing with a sheet that is pre-heated inductively or by the Joule effect due to the passage of an electric current. Reference may be made to the advantageous hot pressing method described in Patent EP2900846B1, or the joining method with less residue described in Patent Application WO2022 / 234214. Inductive hot pressing itself involves heating one or more interconnected sheets or end plates by the Joule effect and then directly applying the layer of the ceramic material to the desired location.

[0049] With further advantages, the thickness of the layer of the conductive ceramic material on each side of the sheet is between 100 μm and 5 mm.

[0050] Attention is also paid to ensuring that the surface area of the layer of ceramic material is minimized so as to increase the local clamping stress applied to the stack. This is because the applied clamping force is constant. Therefore, reducing the surface area of the contact layer will increase the stress (F / S). For example, for a layer of ceramic material with half the surface area under a given force, the stress will double.

[0051] Therefore, in essence, the present invention includes an electrochemical device formed by the conventional alternating stacking assembly of an electrochemical cell and an electro-fluidic interconnect, and at least one mechanical reinforcement element is installed at each stage to withstand the bending forces that tend to occur in the stack during the initial thermo-mechanical treatment step.

[0052] The effect of this treatment is to at least completely install the electrical contact elements and the seals in the stack.

[0053] Furthermore, in the prior art stack, due to the softness of the seal, bending appears during the first temperature rise phase.

[0054] By incorporating mechanical reinforcements made of materials with temperature-variable stiffness, the reinforcements can act by withstanding forces during the first temperature rise.

[0055] These reinforcements, which are preferably made of the same material as the seal and more specifically made of glass-ceramic, remain hard up to the softening / melting temperature of the reinforcement, which is the same as the softening / melting temperature of the seal.

[0056] When this temperature is reached, all mechanical forces are uniformly transmitted to the electrical contact elements.

Advantages of the Invention

[0057] Ultimately, the present invention offers numerous advantages, including the following. - Deformation in the SOEC / SOFC stack is suppressed, which is due to the fact that the contact area between the battery and the electrical contact element can be reduced. - As a natural result, better control of the current level across the SOEC / SOFC stack can be obtained. - Implementing the mechanical reinforcement element is simple and quick, which is incorporated during the step of pressing down the seal. - Since it can be achieved simply by adding beads and / or solid pads made of the same material as the seal, the additional cost is low.

[0058] Other advantages and features will become clearer by reading the following detailed description provided for illustration purposes rather than limitation, with reference to the following figures.

Brief Description of the Drawings

[0059]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0060] For clarity, the same elements of the electrochemical device according to the prior art and the electrochemical device according to the present invention are indicated by the same reference numerals.

[0061] Throughout this patent application, "downward", "upward", "on ~", "under ~", "inside", "outside", "internal", and "external" are understood with reference to the electrochemical device according to the present invention in the configuration of operation, that is, in the state where the modules are stacked vertically.

[0062] It is also pointed out that the described electrolytic cell or fuel cell is of the solid oxide type (SOEC (solid oxide electrolytic cell) or SOFC (solid oxide fuel cell)) that operates at high temperatures.

[0063] Therefore, all components (anode / electrolyte / cathode) of the electrolyte or fuel cell are ceramic.

[0064] The high operating temperature of the electrolytic cell (electrolysis reactor) or fuel cell is typically between 600°C and 1000°C.

[0065] Typically, the characteristics of the SOEC electrolytic cell suitable for the present invention of the cathode-supported type cell (CSC) can be indicated as follows in the following Table 1.

[0066]

Table 1

[0067] Figures 1 and 2 related to the prior art electrochemical device 1 are described in the introduction section. Therefore, those figures are not addressed below.

[0068] Although the harmful deformation in the electrical contact in the stack of the prior art electrochemical device has been described, the inventor has decided to incorporate mechanical reinforcement elements into this type of stack, and the role of the mechanical reinforcement elements is to receive mechanical forces in order to minimize the bending torque during the first temperature rise of the stack, as necessary for the installation of the seal.

[0069] To best follow the deformation of these seals, the inventor has solved this by making these reinforcement elements from the same constituent material, typically the sealing glass-ceramic.

[0070] Therefore, the glass-ceramic of the reinforcement element remains hard up to its softening / melting temperature, after which all mechanical clamping forces will be transmitted to the electrical contact elements.

[0071] Therefore, the reinforcement element made of the same material as the seal acts as an intervening body for receiving forces. Therefore, the forces are received as soon as the bending torque exists and are relieved when the bending torque is reduced.

[0072] A first exemplary embodiment of the mechanical reinforcement element is shown in connection with a plate 9 forming a cover of the electrochemical device having a stack of batteries 2.

[0073] As shown in Figure 3, the cover 9 of the device 1 according to the prior art, in other words, the cover 9 without the incorporation of the reinforcement element for receiving forces, presses against the glass-ceramic seal 7 arranged around the periphery and can also be supported by a support 8 in the form of a mica sheet generally.

[0074] Therefore, under the clamping load C, this type of cover 9 is subjected to bending stresses that can cause its compositional deformation. This is because the seal 7 typically remains hard up to a high temperature of about 650 - 700 °C and then softens and melts for installation. The temperatures and cycles required for the installation of a seal, typically glass or glass - ceramic, can vary depending on the nature of the composition. The temperature can be between 750 °C and 900 °C over a period of 1 to 48 hours in one or more cycles. The temperature rise for the device 1 can be up to 10 °C / min.

[0075] If the mechanical reinforcement element 10 is, preferably, in the form of a glass - ceramic washer, for example at the center of the cover 6, in a notch 80 made in the mica support 8 as shown in Figure 4A, the bending stress is dramatically reduced by the melting of the glass - ceramic.

[0076] As shown in Figure 4B, thanks to the melting of the glass - ceramic, there is no further bending stress for both the seal 7 and the washer 10 forming the force - receiving interposition.

[0077] Figure 5 shows a particular exemplary embodiment of the plate 9 forming the cover with a mica sheet 8 that carries not only the seal 7 around the periphery of the notch 90 opposite the gas passage but also the force - receiving washer 10 in the central notch 80 in the sheet 8.

[0078] Figure 6 shows another example of the integration of the reinforcement element 10 for receiving forces on the surface of the interconnect 3.

[0079] As its electrical contact elements 4, the surface of the interconnect 3 carries a grid of five numbers of gold distributed in a square with one at the center of the square. These grids 4 are preferably welded directly to the surface of the outer sheet of the interconnect 3. The seal 7 is placed in the form of beads around each through - hole 30 intended for the passage of gas in the device 1.

[0080] Glass-ceramic beads 10 that are closed in themselves form a mechanical reinforcement element that will reduce the bending torque that can affect the interconnect 3 during the first temperature rise in order to form a circular ring around the grid 4 at the center.

[0081] Figure 7 also shows another example of the implementation of the mechanical reinforcement element 10 made of glass-ceramic.

[0082] As shown, the solid glass-ceramic pads 10 can be placed at the center of each of the electrical contact layers 5, specifically made from LSM, in the cutouts 50 made for this purpose.

[0083] The solid glass-ceramic pads 10 can also be installed in the cutouts 40 of the electrical contact grid 4, specifically made from nickel.

[0084] This minimizes the bending force at any position of the electrochemical device 1 having a stack of solid oxide cells.

[0085] Regardless of its implementation in the device 1, care is taken to ensure that the surface area of the mechanical reinforcement element 10 does not become overly large so as not to unduly reduce the functional electrochemical surface area of the battery 2. The surface area of the reinforcement element 10 is preferably between 0.1 cm 2 and 10 cm 2 and more preferably 0.5 cm 2 .

[0086] The present invention is not limited to the examples described, and the characteristics of the illustrated examples may, in particular, be combined together among the deformations not illustrated.

[0087] Other deformations and improvements can be expected without departing from the scope of the present invention.

[0088] The mechanical reinforcement element 10 made of a glass-ceramic material according to the invention can preferably be arranged centrally between two components of a stack forming an electrochemical device.

[0089] The plate 9 forming the cover is arranged at the upper end of the stack and can be an end plate having the main functions of hardening, enabling the supply of current across the thick plate, and enabling the filling of forces while returning to the cooled state. In this case, since the end plate does not have the function of passing gas to the stack, it does not have openings appearing on the surface.

[0090] In a stack where, as in patent application EP3955353A1, it is required that the upper end plate has openings appearing on the surface, the cover is formed by an additional plate without openings appearing on the surface.

Explanation of Reference Signs

[0091] 1 Electrochemical device 2 Electrochemical cell 3 Electro-fluidic interconnection, metal element 4 First electrical contact element, grid 5 Second electrical contact element, electrical contact layer 6 End plate, metal element, cover 7 Seal 8 Frame, support, sheet 9 Plate, cover 10 Mechanical reinforcement element, washer, glass-ceramic beads, solid glass-ceramic pad 30 Through-hole 40, 80, 90 Notch C Axial load, clamping load P Support point

Claims

1. An electrochemical device (1) intended to operate at high temperatures, constituting an electrolytic or co-electrolytic reactor of the SOEC type or a fuel cell of the SOFC type, A stack of electrochemical cells (2) of the solid oxide based SOEC / SOFC type and electrofluidic interconnects (3) arranged individually on either side of each of said electrochemical cells, each interconnect comprising at least one component made of an electronically conductive gas-tight material for supplying or withdrawing electric current to said cell and for supplying, withdrawing and circulating gas across each electrode of each electrochemical cell; two plates (6) located at the ends of the stack, called end plates; a plurality of electrical contact elements (4, 5) each disposed in contact with a face of one of the end plates, in contact with an electrode of the electrochemical cell, or in contact with a face of an interconnect; a plurality of seals (7) each disposed around each of the through holes to ensure sealing around each gas inlet / outlet in said stack; a plurality of mechanical reinforcing elements (10) each disposed in contact with a face of one of the end plates, in contact with an electrode of the electrochemical cell, or in contact with a face of an interconnect, the plurality of mechanical reinforcing elements (10) being made of an electrically insulating material exhibiting a stiffness that is variable as a function of temperature and substantially equal to a stiffness of the seal, such that, prior to operation of the device, at a first increase in temperature of the device, the stiffening elements soften simultaneously with the seal and then melt, thereby limiting bending of the end plates and the interconnect; An electrochemical device (1).

2. 2. The electrochemical device of claim 1, wherein the mechanical reinforcement element comprises the same material of construction as the seal, preferably glass ceramic.

3. 3. The electrochemical device of claim 1 or 2, wherein at least a portion of the mechanical reinforcement element is located at a center of the face of the end plate, a center of the electrode of the electrochemical cell, or a center of the face of the interconnect.

4. The surface area of ​​the mechanical reinforcement element is less than 0.1 cm ２ From 10 cm ２ and more preferably between 0.5 cm ２ 4. The electrochemical device according to claim 1 ,

5. 5. An electrochemical device according to claim 1, wherein the mechanical reinforcement elements are in the form of beads, preferably closed in themselves, and / or in the form of solid pads.

6. Electrochemical device according to any one of claims 1 to 5, wherein the electrical contact elements comprise at least one conductive grid, preferably made from gold.

7. 7. An electrochemical device according to claim 6, wherein the number of said grids in contact with one battery electrode is between 1 and 10, preferably 5.

8. The surface area of ​​the grid is 0.5 cm ２ From 5 cm ２ Between 1 cm and 2 cm, preferably ２ The electrochemical device according to claim 6 or 7,

9. 9. An electrochemical device according to any one of claims 6 to 8, wherein one or more of the grids are welded directly to the faces of the interconnects and / or to the faces of the end plates.

10. 10. The electrochemical device of any one of claims 6 to 9 in combination with claim 5, wherein the mechanical reinforcement element is in the form of a solid pad placed in a notch made in the center of the grid.

11. 11. An electrochemical device according to any one of claims 6 to 10, comprising a grid of five in number, distributed in a square or rectangle, one in the centre of said square or rectangle, in contact with one battery electrode.

12. 12. The electrochemical device of claim 11 in combination with claim 5, wherein the mechanical reinforcement element is in the form of a bead closed on itself and surrounding the grid at the center of the square or rectangle.

13. 6. An electrochemical device according to claim 1, wherein the electrical contact element comprises at least one layer of a conductive ceramic material.

14. The conductive ceramic material is Lạ ０．６ Sr ０．４ Co ０．８ Fe ０．２ O ３ (LWFF) L ０．８ Sr ０．２ Cổ ０．９ Fe ０．１ O ２．５ (Lyrics) L ０．７ Sr ０．３ Yes ３ (L.S.) Sm ０．５ Sr ０．５ CoO ３ (SSC)、 Smmpa ０．５ Sr ０．５ Co ２ O ５ (SSBSC), GdSrCo ２ O ５ (GSC)、 <h2 style=";text-align:left;direction:ltr">La<h2 style=";text-align:left;direction:ltr"> ０．６５ <h2 style=";text-align:left;direction:ltr"> 25<h2 style=";text-align:left;direction:ltr"> ０．３ <h2 style=";text-align:left;direction:ltr"> MnO<h2 style=";text-align:left;direction:ltr"> ３ <h2 style=";text-align:left;direction:ltr"> ((LSM)、 LaBaCo ２ O ５ (LBC)、 YBaCo ２ O ５ ((YBC)、 !) １．８ 5 ０．２ u ４ (#|)、 Lạ ０．８ Sr ０．２ Co ０．３ Mn ０．１ Fe ０．６ O ３ (LWPMF) L ０．９８ Ni ０．６ Fe ０．４ O ３ (LNF), La １．２ 3r ０．８ 9iｯ ４ (LSX)、 La ０．７ Sr ０．３ FeO ３ (LSF)、 Lạ ２ Ni ０．６ Cu ０．４ O ４ (LNC) 14. The electrochemical device of claim 13, wherein the conductive layer is selected from the group consisting of:

15. 15. An electrochemical device according to claim 13 or 14, wherein the layer of conductive ceramic material is hollow through at least a portion of its thickness.

16. 16. An electrochemical device according to any one of claims 13 to 15, wherein the layers of conductive ceramic material are preferably joined by hot pressing, with an adhesive or with one or more interconnect sheets which are preheated inductively or by Joule effect by the passage of an electric current.

17. 17. An electrochemical device according to any one of claims 13 to 16, wherein the layer of conductive ceramic material has a thickness between 100 μm and 5 mm.

18. 18. The electrochemical device of any one of claims 13 to 17 in combination with claim 5, wherein the mechanical reinforcement element is in the form of a solid pad placed in a notch made in the center of the ceramic layer.

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