Module for an electrochemical device having a relatively long useful life

Abstract

1. An interconnector (I) for an electrochemical module comprising a stack of electrochemical cells (CL) and interconnectors (I) and an electrical insulating element between two interconnectors (I) surrounding the cells (CL), wherein each cell (CL) is arranged between the two interconnectors (I) and is in electrical and mechanical contact with said interconnectors (I), the interconnector comprising at least one intermediate plate received between two end plates defining a gas supply and gas collection chamber therebetween, the intermediate plate comprising a central region externally bounded by lateral regions comprising n lateral branching regions (6), n being at least equal to 1, each lateral extension being configured to be movable towards and to come into contact with a lateral extension (6) of an intermediate plate immediately adjacent to the interconnector (I) in the stack, in order to provide electrical conductivity between the two interconnectors (I), the intermediate plate being not covered by at least one of the two end plates in the lateral branching regions (6).

Description

Technical Field

[0001] The present invention relates to a module for an electrochemical device having a relatively long useful life.

Background Art

[0002] Electrochemical devices may be used for electrolysis at high temperatures and may include a stack of solid oxide electrolysis cells (SOECs), or may comprise a stack of solid oxide fuel cells (SOFCs) as fuel cells.

[0003] Such devices comprise a module or stack including a stack of electrochemical cells fixed between two fixing plates. The cells are electrically connected in series.

[0004] Each electrochemical cell includes an electrolyte between two electrodes. Interconnecting plates are arranged between the cells to ensure electrical connection between the cells. Further, the interconnecting plates ensure gas supply to the cells and collection of the generated gas in each cell. European Patent No. 3183379 describes an example in which an interconnecting plate or connector ensures electrical connection and gas diffusion within the cell. The interconnecting device includes three thin plates. One of them is known as an intermediate plate and is arranged between the other two plates. The other two plates are known as end plates. The intermediate plate ensures reliable diffusion of the gas in the oxygen and hydrogen chambers.

[0005] One of the end plates forms a framework, delimits the openings on the intermediate plate, and receives the cell, which then contacts the intermediate plate. The current flows through the regions of the cell and the interconnecting device from the lower end to the upper end, or from the upper end to the lower end, and they are in vertical cooperation with the cell.

[0006] During operation, the anode and the cathode are the reaction sites of the electrochemical reaction. On the other hand, the electrolyte enables the movement of ions from the cathode to the anode, and vice versa, depending on whether the electrochemical device is operating in electrolysis mode or fuel cell mode.

[0007] Therefore, in the electrolysis mode, the cathode compartment allows for the supply of water vapor and the discharge of products, particularly by the reduction of water such as hydrogen. On the other hand, the anode compartment ensures the discharge of oxygen molecules generated by the oxidation of O 2- ions that have moved from the cathode to the anode via the exhaust gas.

[0008] The mechanism of electrolyzing water vapor by a basic electrochemical cell (the "SOEC" mode) is as follows. During this electrolysis, the basic electrochemical cell is supplied by an electric current flowing from the cathode to the anode. The water vapor passed through the cathode compartment is then reduced by the effect of the electric current according to the following half-reaction equation. 2H 2 O + 4e - → 2H 2 + 2O 2-

[0009] The hydrogen molecules generated during this reaction are then discharged. On the other hand, the O 2- ions generated during this reduction move from the cathode to the anode through the electrolyte, and at the anode, the O 2- ions are oxidized to oxygen molecules according to the following half-reaction equation. 2O 2- → O 2 + 4e -

[0010] Next, the oxygen molecules thus formed are discharged by the exhaust gas circulating in the anode compartment.

[0011] The electrolysis of water vapor corresponds to the following reaction equation. 2H 2 O → 2H 2 + O 2

[0012] In the fuel cell mode (SOFC), air is injected into the cathode compartment and decomposed into O 2― ions. O 2―Ions move towards the anode and react with the hydrogen molecules circulating within the anode compartment to form water. Instead of a fuel cell, CH 4 and air are supplied.

[0013] By operating in a fuel cell mode, an electric current can be generated.

[0014] These systems can operate in a temperature range of 600 °C or higher and 1000 °C or lower.

[0015] To ensure good electrical connection between the interconnecting plates and the cells and the sealing of the laminate, the fixing plate exerts a molding force on the laminate.

Prior Art Documents

Patent Documents

[0016]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0017] Temperature control of the cell stack and the interconnect is complex. In fact, for example, in an SOEC, depending on the operating point used, which is characterized by the total current and the terminal voltage in each cell, endothermic or exothermic reactions occur. For a cell, when the terminal voltage is less than 1.3 V, the cell consumes heat during the electrochemical reaction, but when the terminal voltage is greater than 1.3 V, the cell generates heat. Since the generation or consumption of heat causes a thermal gradient within the stack, this thermal control is complex. These gradients create thermo-mechanical stresses that can cause damage to the object. Furthermore, due to a significant temperature increase, the sealing between the interconnects can be damaged, especially in the case of glass or glass-ceramic.

[0018] For example, when there is an insufficient electrical connection or a defect in the cell due to cell degradation, the voltage of the terminal increases, resulting in heat generation.

[0019] The heating phenomenon also occurs in a fuel cell in which at least one of the cells has a defect.

[0020] Nevertheless, since its sealing is complicated and the laminate is brittle, when it includes a ceramic portion sealed with, for example, glass or glass ceramic, it is impossible to remove the laminate in order to replace a defective cell. As a result, in the case of a laminate composed of many cells, even if one cell does not operate normally, the entire laminate must be stopped.

[0021] Furthermore, it should also be noted that when a problem occurs regarding the flow of the reducing gas on the cell, it can be re-oxidized to become an insulator. In this case, since there is an insulating stage, it is impossible for the entire laminate to operate.

[0022] When the number of cells included in the laminate is large, these risks become greater.

Means for Solving the Problems

[0023] Therefore, one object of the present invention is to propose a module for an electrochemical device having a relatively long effective life by means of restricting a heat source and / or avoiding insulating cells.

[0024] The above object is achieved by an interconnector for an electrochemical module including a laminate of electrochemical cells and an interconnector inserted between the cells. The interconnector includes means for short-circuiting one or a plurality of electrochemical cells when the voltage of the interconnector or their terminals is too high and / or when the cell is insulating.

[0025] Therefore, when the cell is a location of excessive heating due to deterioration of the cell or its electrical connection and / or when the cell becomes insulating, particularly due to reoxidation, the cell will become electrically insulating. The cell will no longer operate, but the module can continue to operate, and in particular, the risk of destruction of the laminate due to overheating is eliminated. Since the defective cell cannot be replaced, the module thus has a long lifespan compared to the prior art modules that are discarded.

[0026] Thus, according to one of its aspects, the object of the present invention is an interconnector for an electrochemical module comprising an electrochemical cell, a stack of interconnecting elements, and an electrical insulating element, each cell being arranged between two interconnectors, being electrically and mechanically connected to said interconnectors, and each electrical insulating element being arranged between two interconnectors and surrounding the cell. The interconnector comprises at least one intermediate plate received between two end plates defining a gas supply and a gas collection chamber therebetween, the intermediate plate comprising a central region externally delimited by a lateral region comprising n lateral branching regions, n being equal to at least 1, each lateral branching region being configured to be movable towards a lateral branching region in the intermediate plate of the directly adjacent interconnector in the stack, being configured to contact it in order to supply electrical conduction between two interconnectors, and the intermediate plate not being covered by at least one of the two end plates in the lateral branching region.

[0027] In other words, the module incorporates means for selectively short - circuiting the cells within the stack.

[0028] The interconnector according to the present invention can further comprise one or more of the following features, either alone or according to any possible technical combination.

[0029] According to a first aspect, all or part of the n lateral branching regions may be in the form of n exposed regions of the intermediate plate that are not superimposed on at least one of the two end plates. In particular, they may be in the form of n exposed regions located at one or more corners of the intermediate plate. They may in particular be obtained by cutting at least one of the two end plates.

[0030] According to a second aspect, all or part of the n lateral branching regions may be in the form of n lateral extensions protruding externally in relation to the lateral region of the intermediate plate. The n lateral extensions extend laterally beyond the edge of the end plate. Thus, the interconnect may include one or more protrusions, or may also include knobs, protruding from the lateral region and may be connected to the protrusions of the interconnect located directly above or below the stack in order to short-circuit the cells between two interconnects.

[0031] The means for short-circuiting are configured to have an impedance lower than the impedance of the interconnect and cell assembly to be short-circuited.

[0032] Most preferably, the lateral branching regions may be distributed on the outer contour of each interconnect around the axis of the stack, thereby limiting the interference imposed on the operation of the cells upstream and downstream of the short-circuited cell.

[0033] The lateral branching regions may be integral with the intermediate plate.

[0034] Furthermore, the lateral branching regions may be covered with an electrically conductive material such as, for example, a cobalt manganese or cobalt cerium alloy to prevent corrosion.

[0035] Moreover, according to another aspect, another object of the present invention is a module for an electrochemical device including a stack of an electrochemical cell and an interconnector as defined above, and an electrical insulating element, each cell being disposed between two interconnectors, said interconnectors being electrically and mechanically connected, and the side branch regions of two directly adjacent interconnectors being at least partially opposed to each other.

[0036] The electrical insulating element may be made of mica.

[0037] Advantageously, the electrically conductive element may be applied between the side branch regions of two directly adjacent interconnectors, in particular, a gold gate and / or a gold paste may be used.

[0038] Furthermore, the ratio between the branch surface formed by the side branch regions of two interconnectors and the active surface of the cell located between the two interconnectors may be between 1 / 100 and 1 / 2, preferably equal to 1 / 10.

[0039] Each electrical insulating element may cover the side branch region.

[0040] Furthermore, each electrical insulating element may include a pre-cut portion for facilitating the removal of a part of the electrical insulating element that coincides with the side branch region.

[0041] In addition, the electrical insulating element may also provide a seal between two interconnectors.

[0042] Moreover, according to another aspect, another object of the present invention is a solid oxide electrolysis device including a module as defined above, a gas supply to the cells, a collection of the gases generated in each cell, and a power supply configured to supply power to the cells in series.

[0043] According to another aspect, another object of the present invention is a module as defined above, hydrogen molecules (H 2 ) and oxygen molecules (O 2 ) or methane (CH 4and a supply of air to the cells, and a collection of the gases produced by each cell, and means for collecting the current produced by each electrochemical cell, a solid oxide fuel cell.

[0044] Furthermore, another object of the present invention according to another aspect is a method for short-circuiting cells as defined above, the following steps: Possibly by deformation, arranging the n lateral branch regions of the interconnects disposed directly on both sides of the cell to contact each other so as to move the lateral branch regions towards each other; Connecting the lateral branch regions to form n electrically conductive paths between two interconnects, a method.

[0045] The connection may be achieved by spot welding.

[0046] In addition, the method may include, prior to their connection, the step of removing the oxide layer on each lateral branch region by abrasion.

[0047] The present invention will be better understood based on the following description and the accompanying drawings.

Brief Description of the Drawings

[0048]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0049] In FIGS. 1 and 2, a schematic view of an example of an embodiment of a module for an electrochemical device according to the present invention can be seen.

[0050] The electrochemical device to which the module may belong may be intended to be implemented for high-temperature electrolysis (SOEC mode) or as a fuel cell (SOFC mode).

[0051] The module includes a stack of electrochemical cells or solid oxide cells. Each basic electrochemical cell CL is formed of a cathode, an anode, and an electrolyte disposed between the anode and the cathode. The electrolyte is solid and a dense ion conductor, and the anode and the cathode are porous layers.

[0052] The module further includes an interconnect I, which is inserted between two consecutive cells, respectively, to ensure an electrical connection between the anode of one cell and the cathode of the adjacent cell. The interconnect I ensures a series connection of the basic cells.

[0053] The number of cells included in the module may be one or more and several hundreds or less, preferably 25 or more and 100 or less.

[0054] The interconnect also serves to separate fluid compartments at the surfaces of the electrodes that are in contact with each other.

[0055] The surface of the interconnect I that contacts the anode of the basic electrochemical cell CL delimits a section known as the anode compartment, and the surface of the interconnect I that contacts the cathode of the basic electrochemical cell CL delimits a section known as the cathode compartment.

[0056] Each of the anode compartment and the cathode compartment enables the gas to flow through and be collected.

[0057] For example, during the electrolysis of water, the cathode compartment ensures the supply of cathode steam and discharges the generated hydrogen. The anode compartment ensures the circulation of the exhaust gas and discharges the oxygen generated at the anode.

[0058] The module may include terminal plates P disposed on both sides of the module. The terminal plates are electrically conductive.

[0059] The device also includes pipes (not shown) for flowing the gas and pipes for collecting the gas.

[0060] Generally, the electrochemical device also includes a fixing system (not shown) with two fixing plates, which are disposed on both sides of the module in the stacking direction and are intended to exert a clamping force on the stack via tie rods.

[0061] At least one gas circulation pipe is provided on both or one of the two fixing plates, which enables the gas to be circulated from the gas inlet to the gas outlet to supply gas to the solid oxide stack or discharge gas from the solid oxide stack.

[0062] The gas inlet and the gas outlet are respectively disposed on one and the other of the surfaces having the largest surface of the fixing plate.

[0063] Each interconnect I has a substantially flat shape and includes a central region ZC and a lateral region ZL surrounding the central region ZC.

[0064] The interconnect has a surface area larger than that of the cell, and each cell contacts the central region ZC of the interconnect by one surface and contacts the central region ZC of the other interconnect by the other surface.

[0065] The electrical insulating element 2 is sandwiched between the interconnects, more specifically, between the lateral regions ZL of two interconnects that contact the same cell. The electrical insulating element 2 forms a frame surrounding the cell. The electrical insulating means is made of, for example, mica, vermiculite, thermiculite, or any other material having excellent heat insulation characteristics at high temperatures.

[0066] For example, preferably, the electrical insulating element 2 associated with the glass ceramic ensures sealing. An example of such an element is described in EP1362100, which includes auxiliary means such as mica, surrounds the cell, contacts the lateral regions of the interconnects, and is a means for ensuring sealing, such as made of glass or glass ceramic. The auxiliary means includes a path passing through both sides to connect two surfaces in contact with the interconnects. During the fabrication of the module, sufficient pressure and heat are applied to cause the melting of the glass, and the glass flows through the path to bring the two interconnects into contact, ensuring sealing.

[0067] Furthermore, means for electrically connecting the stack are provided for supplying cells in series in the case of an electrolyzer or for collecting the generated current in the case of a fuel cell. In FIG. 1, the electrical connection means includes a current rod C1 connected to the lower terminal plate and a current rod C2 connected to the upper terminal plate. Preferably, the current flows upward from the bottom surface.

[0068] Each interconnect I includes a short - circuit means 4. The short - circuit means 4 of the interconnect I in contact with one surface of the cell can cooperate with the short - circuit means 4 of the interconnect I in contact with the other surface of the cell to short - circuit the present cell. Thus, in the case of an electrolyzer, it limits the current flowing through it, reduces the voltage at its terminals, and the generation of heat.

[0069] According to the present invention, the short - circuit means 4 includes one or more lateral branch regions 6 in the interconnect I, and takes the form of a lateral extension 6 as in the examples of FIGS. 1 - 5 and the form of an exposed region 6 as in the example of FIG. 6.

[0070] It cannot be said that the intermediate plate 8 is advantageously covered by the end plates 10, 12 in these lateral branch regions 6.

[0071] The lateral branch region 6, which takes the form of a lateral extension as in the examples of FIGS. 1 - 5, extends from the outer edge of the interconnect I. As a result, this or these extensions project from the entire outer - lateral surface of the laminate within the laminate.

[0072] In the example of FIG. 6, the lateral branch region 6 takes the form of an exposed region 6 obtained by modifying the end plates 10, 12 one or more times so as not to cover the scattered intermediate plates 8, particularly the corners or vertices of the intermediate plate 8 as seen in FIG. 6. Thus, at these corners, the end plates 10, 12 are shrunk.

[0073] In other words, the lateral branch region 6 is obtained by shrinking at least one of the end plates 10, 12 and / or expanding the intermediate plate 8 beyond its lateral region ZL.

[0074] The lateral branch region 6 is thus arranged to contact the lateral branch region 6 of the interconnect I arranged directly below or above the laminate, and in the case of the lateral extension 6, it can be particularly deformed.

[0075] In the laminate, each lateral branch region 6 of the interconnect I is arranged at least partially along the lateral branch region 6 of each interconnect I, and advantageously, completely along the lateral branch region 6 of each interconnect I. Thus, each lateral branch region 6 resulting from a simple deformation of the interconnect I from its normal form to the intermediate plane can be arranged in contact with the lateral branch region 6 of the interconnect I arranged directly above or below. The intermediate plane of the interconnect I is planar, and the interconnect I expands and has its maximum dimensions.

[0076] When two side branch regions 6 of two interconnects I arranged on both sides of the cell are placed in contact and preferably assembled by tacking as shown in FIG. 2, the cell is electrically short-circuited and preferably current flows through the side branch region 6. A very small current also flows within the cell. Tacking enables effective assembly while limiting the risk of degradation of the elements surrounding the side branch region 6. Alternatively, welding by adding material is used for connection, but specific precautions must be taken so as not to degrade the rest of the laminate. In particular, in the case of exposed extensions as shown in FIG. 6, a substance with high conductivity, for example, a gold gate, a gold paste or any other substance with high conductivity, can also be added between the two side branch regions 6 so as to advantageously act on the connection.

[0077] Preferably, the short-circuit means includes a plurality of side extensions forming protrusions, which are distributed around the entire outer edge of the interconnect. When the cell is short-circuited, the distribution of the current flowing just between the two interconnects then becomes more homogeneous, which is preferable for the operation of the cells located upstream and downstream of the short-circuited cell. Upstream and downstream are considered with respect to the direction in which the current flows within the laminate. Furthermore, outside the unused region of the laminate, that is to say outside the central region ZC, the heating is reduced and compensated. The heating of the side extensions is not important for the electrolyzer.

[0078] In FIGS. 3 and 4, an example of a first embodiment of the interconnect according to the present invention can be seen. And in FIG. 6, an example of a second embodiment of the interconnect according to the present invention can be seen. FIGS. 3 and 4 are depicted here, but the same reference numerals in FIG. 6 designate the same or similar elements.

[0079] Thus, the interconnect I includes an intermediate plate 8 and two end plates 10, 12, and the intermediate plate 8 is received between the end plates. An example of the structure of such an interconnect without short-circuit means is described in European Patent No. 3183379.

[0080] The three plates delimit the supply chamber therebetween. For example, in the case of an electrolyzer, the intermediate plate 8 enables the supply of gas to the chamber with oxygen of the plate 10 and also to the chamber with hydrogen of the plate 12.

[0081] The intermediate plate 8 includes a central portion 8.1 intended to contact the cell surface and a lateral portion 8.2 surrounding the central portion 8.1 including holes 14. In this example, the lateral portion 8.2 includes four hole groups, each distributed along the outer edge 8.3 of the intermediate plate 8. The holes are in a slot shape and are connected by holes perpendicular to one end and parallel to one end.

[0082] The first end plate 10 includes a central portion 10.1 hollowed out so as to surround the cell and a lateral portion 10.2 surrounding the central portion. The lateral portion 10.2 includes four holes 16, each extending in a direction parallel to the outer edge 10.3 of the first end plate. Each hole is formed by an elongated groove.

[0083] The second end plate 12 includes a central portion and a lateral portion. The lateral portion includes four holes 18, each extending in a direction parallel to the outer edge of the second end plate. Each hole is formed by an elongated groove.

[0084] Here, within the scope of the present invention, "hole" means a hole opening on one side of the plate.

[0085] The three plates 8, 10, 12 also include guide holes 19, for example in a circular and / or elliptical shape, so as to allow guide rods to pass through. These rods are enabled to be guided during tightening at various stages, and the holding force is exerted at the top of the laminate and conducted across the entire surface.

[0086] The intermediate plate 8 and the two end plates 10, 12 have the same surface, or substantially the same surface. When the three plates are stacked, the outer edges of the three plates are aligned with each other along the vertical direction to define the four lateral surfaces of the laminate, forming the lateral surfaces of the laminate. It will be understood that the shapes of the other plates can be considered, for example, polygonal, or even circular or elliptical shapes.

[0087] Preferably, the plates are metal sheets, and advantageously made of ferrite steel. The thickness of the plates is generally 0.1 mm or more and 1 mm or less, and advantageously equal to 0.2 mm.

[0088] Furthermore, the intermediate plate 8 includes the lateral extensions 6 as in the examples of FIGS. 3 and 4. However, in the example of FIG. 6, it relates to the exposed lateral region 6.

[0089] When the cells and the interconnects are stacked, the lateral extensions 6 of the interconnect I protrude from the lateral surface of the laminate and become available.

[0090] In this example, three extensions are provided on each edge 8.3 of the plate. The extensions are arranged on the four outer edges. Since the corners are more convenient to use, extensions are provided on both sides of each corner as in the example shown. The number of lateral extensions is not limited and is selected according to the surface of each extension so that the assembled part represents a sufficiently large surface. As a result, the electrical conductivity of the branched surface formed by the assembly of the lateral extensions is superior to that of the cells that can be short-circuited.

[0091] In this example, the lateral extensions have a rectangular shape, which can provide a large contact surface between the lateral extensions that prefer heat conduction. Other shapes are also possible, such as triangular or partially circular.

[0092] Advantageously, for the active surface of 100 cm 2 , that is, corresponding to the surface of the cells and the surface of the central region 8.1 of the intermediate plate, the total of the branched surfaces in the plane formed by all of the lateral extensions is 1 cm 2 or more and 50 cm2 is as follows, preferably 10 cm 2 is equal to.

[0093] Advantageously, the ratio of the branched surface to the active surface is between 1 / 100 and 1 / 2, preferably equal to 1 / 10.

[0094] The number of lateral extensions is advantageously at least 4 and at most 24, more preferably equal to 12 as shown in FIGS. 3 and 4.

[0095] In such an embodiment, the voltage of the defective cell may be reduced to a value substantially between 0 V and 0.5 V, preferably equal to 0.1 V.

[0096] In an example of an advantageous embodiment, at least the lateral extensions are covered by a layer that prevents corrosion, such as a layer of cobalt manganese or cobalt cerium alloy. Thus, the electrical conductivity is not reduced by an electrically insulating oxide layer when connecting the lateral extensions of the two interconnects. Instead, a step is provided of removing the oxide layer that may form on the lateral extensions while the connection is being made, especially on the surfaces where contact is intended. This removal is done, for example, by abrasion.

[0097] In an example of another embodiment, each intermediate plate includes one lateral extension formed by expanding the lateral edge of the intermediate plate. Despite the fact that the connection with the intermediate plate of the other interconnect can be complex, this example has the advantage of providing a large branched surface.

[0098] Preferably, the lateral extensions are integral with the intermediate plate, thereby reducing the electrical resistance and simplifying the manufacturing. The lateral extensions may be generated by simultaneously cutting the rest of the intermediate plate. Instead, the lateral extensions are fixed to the intermediate plate, for example, by welding.

[0099] Advantageously, the intermediate plate, like the lateral extensions and end plates 10, 12, is made of Crofer 22 or K41 type ferritic steel.

[0100] An advantageous example of the embodiment shown in FIG. 5 is that as long as the cells between the two interconnects are operating normally, the side extensions 6 are covered, and as a result, in order to ensure electrical insulation even between the two overlapping side extensions 6, the electrical insulation element 2 has a spread on the plane.

[0101] When it is desired that the connection between the two interconnects short-circuits the cells placed between these two interconnects, a part of the element 2 covering the side extensions is removed so that the facing side extensions can be placed in contact.

[0102] Very advantageously, a part of the electrical insulation element 2 that coincides with the side extensions 6 is delimited by the pre-cut parts 20, facilitating their removal by simple breakage if necessary.

[0103] Here, an example of a method for short-circuiting the cells will be described.

[0104] When a defective cell is detected in the stack, it is decided to electrically insulate it from the other parts of the stack in order not to degrade the operation of the device. This detection is obtained, for example, by measuring the voltage of each cell carried out to monitor changes in the life state of the stack.

[0105] The side extensions 6 of the intermediate plates located on both sides of the defective cell are moved in an out-of-plane direction towards each other. That is, each side extension 6 is deformed towards the side extension 6 facing the other intermediate plate. Then, preferably by temporary welding, they are made integral. Note that since the thickness of the side extensions is on the order of several tens of mm, they may be easily deformed. Furthermore, the distance between the two facing side extensions is on the same order as the thickness of the cell and the layers it contacts, that is, on the order of 1 mm. As a result, little deformation is required to arrange the side extensions to be in contact.

[0106] The lateral extensions in the two intermediate plates are all subsequently connected to form a branched surface that is more electrically conductive than the defective cells. Then, as schematically shown in FIG. 2, the current i flows directly from one intermediate plate to the other, and the voltage of the defective cells drops and no heat is generated.

[0107] To explain the effectiveness of the present invention, the voltage at the terminals of each cell in the laminate was measured according to the applied current in the case of a laminate composed of 25 cells with an active surface of 100 cm 2 and the laminate was operating in an electrolysis state. The gas is a mixture of 90% water vapor and 10% hydrogen flowing at a flow rate of 6 Nml / min / cell / cm 2 .

[0108] In FIG. 7, the change in voltage (V) over time (h) can be seen when the current i (A) is gradually increased. The maximum acceptable current value is 15 A, because when a current larger than this is applied, the voltage of two cells exceeds 1.4 V. These two cells are defective. When this voltage is exceeded, they generate heat.

[0109] In FIG. 8, the voltage change when a current of 50 A is applied to the same laminate under the same conditions can be seen, but the defective cells are insulated. A voltage on the order of 0.1 V occurs in the two defective cells, and it can be seen that the other cells operate normally without the cell voltage exceeding 1.4 V and hydrogen is generated. Furthermore, it is observed that the voltage durability of the cells with branches is good. In addition, the temperature of the laminate was also measured, showing stability and proving the effectiveness of the present invention.

[0110] According to the present invention, it is relatively easy to insulate one or more defective cells in order to protect the operation of the module and extend its useful life.

Description of Reference Numerals

[0111] 2: Electrical insulation element 4: Short-circuit means 6: Lateral branching region 8: Intermediate plate 8.1: Central part 8.2: Lateral part 8.3: Outer edge 10: End plate 10.1: Central part 10.2: Lateral part 10.3: Outer edge 12: End plate 14: Hole 16: Hole 18: Hole 19: Guide hole 20: Pre-cut part I: Interconnector i: Current P: Terminal board CL: Electrochemical cell C1: Current rod C2: Current rod ZC: Central region ZL: Lateral region

Claims

1. A stack of an electrochemical cell (CL) and an interconnect (I), and an electrical insulation element (2), each cell (CL) being disposed between two interconnects (I), said interconnect (I) being electrically and mechanically connected, said electrical insulation element (2) being sandwiched between two interconnects (I) respectively and surrounding the cell (CL), an interconnect (I) for an electrochemical module, each of said interconnects (I) comprising at least one intermediate plate (8) received between two end plates (10, 12) defining a gas supply and gas collection chamber therebetween, said intermediate plate (8) comprising a central region (ZC) externally delimited by a lateral region (ZL) comprising n lateral branching regions (6), n being equal to at least 1, each lateral branching region (6) being configured to be movable towards the lateral branching region (6) of the intermediate plate immediately adjacent to the interconnect (I) within the stack and being configured to contact it to provide electrical conductivity between two interconnects (I), said intermediate plate (8) being an interconnect not covered by at least one of the two end plates (10, 12) in the lateral branching region (6).

2. The interconnect according to claim 1, wherein all or part of the n lateral branching regions (6) are in the form of n exposed regions (6) of said intermediate plate (8) and are not superimposed on at least one of the two end plates (10, 12), in particular in the form of n exposed regions (6) located at one or more corners of said intermediate plate (8).

3. The interconnect according to claim 1 or 2, wherein all or part of the n lateral branching regions (6) are in the form of n lateral extensions (6) protruding externally with respect to the lateral region (ZL) of said intermediate plate (8), said n lateral extensions extending laterally in particular beyond the edges of the end plates (10, 12).

4. The interconnect according to claim 1, wherein the lateral branching regions (6) are distributed around the outline of each interconnect (I) around the axis of the stack.

5. The interconnect according to claim 1, wherein the lateral branching regions (6) are integral with the intermediate plate.

6. The interconnect according to claim 1, wherein the lateral branching regions (6) are covered with an electrically conductive material to prevent corrosion.

7. A module for an electrochemical device, comprising a laminate of an electrochemical cell (CL) and an interconnect (I) according to claim 1, and an electrical insulation element (2). A module in which each cell (CL) is placed between two interconnects (I), is in electrical and mechanical contact with the interconnects (I), and the lateral branch regions (6) of two directly adjacent interconnects face each other at least partially.

8. The module according to claim 7, wherein an electrically conductive element is added between the lateral branch regions (6) of two directly adjacent interconnects (I).

9. The module according to claim 7, wherein the ratio of the branch surface formed by the lateral branch regions (6) of two interconnects (I) to the active surface of the cell located between the two interconnects (I) is between 1 / 100 and 1 / 2.

10. The module according to claim 7, wherein each electrical insulation element (2) covers the lateral branch region (6).

11. The module according to claim 10, wherein each electrical insulation element (2) includes a pre-cut portion (20) for facilitating the removal of a part of the electrical insulation element that coincides with the lateral branch region (6).

12. A solid oxide electrolysis device, comprising the module according to any one of claims 7 to 11, a gas supply to the cells, a gas collection generated for each cell, and a power supply configured to supply power to the cells in series.

13. The module according to any one of claims 7 to 11, and the supply of hydrogen molecules (H ２ ), oxygen molecules (O ２ ), or methane (CH ４ ) and air to the cell, the collection of the gas generated from each cell, and means for collecting the current generated from each electrochemical cell. A solid oxide fuel cell comprising the same.

14. A method for short-circuiting the cells of the module according to any one of claims 7 to 11, comprising the following steps: Arranging the n lateral branch regions (6) of the interconnects (I) directly disposed on both sides of the cell so as to contact each other in order to move the lateral branch regions (6) towards each other; Connecting the lateral branch regions (6) to form n electrically conductive paths between the two interconnects (I).

15. The method according to claim 14, further comprising the step of removing the oxide layer on each lateral branch region (6) by abrasion prior to their connection.

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