EP4244922A1

EP4244922A1 - Clamping device for an electrochemical stack, assembly formed by the clamping device and the electrochemical stack

Info

Publication number: EP4244922A1
Application number: EP21823638.8A
Authority: EP
Inventors: Michel Planque; Guilhem Roux
Original assignee: Commissariat a lEnergie Atomique CEA; Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 2020-11-16
Filing date: 2021-11-15
Publication date: 2023-09-20
Also published as: WO2022101591A1; FR3116387B1; FR3116387A1

Abstract

The invention relates to a clamping device (400) for an electrochemical stack (200), said device comprising: - an upper clamping plate (410) and a lower clamping plate (420) facing each other; - at least one helical spring (500) for clamping the two clamping plates (410, 420) against an electrochemical stack (200) capable of being clamped between said clamping plates (410, 420), wherein the at least one helical spring (500) is provided with at least one continuous fluid flow channel (510) that is formed in the volume thereof and passes through each of the turns of the at least one helical spring (500); - at least one retaining means for maintaining the clamping force applied by the at least one helical spring (500) to the clamping plates (410, 420).

Description

Title: CLAMPING DEVICE FOR AN ELECTROCHEMICAL STACK, AND ASSEMBLY FORMED BY THE CLAMPING DEVICE AND THE ELECTROCHEMICAL STACK

TECHNICAL AREA

The present invention relates to the field of clamping devices and in particular to clamping devices for electrochemical stacks. Said electrochemical stacks considered are in particular stacks of the SOEC or SOFC type capable of operating at temperatures above 700° C.

The invention relates in particular to a clamping device provided with a helical spring intended to exert a force leading to the clamping, or even to the crushing, of the electrochemical stack. The helical spring, according to the terms of the present invention, is in particular provided with thermalization means, and more particularly with a fluid circulation channel in which a cooling fluid is capable of flowing in order to maintain said spring in a range temperatures for which the force exerted by said spring varies little.

PRIOR ART

FIG. 1 represents an electrochemical device 100 known from the state of the art and described in document FR 3 045 215 cited at the end of the description.

The electrochemical device comprises a stack 200 of solid oxides operating at high temperature clamped between two clamping plates 300 and 310 able to operate either in electrolyser mode or in fuel cell mode. Clamping rods, extending between the two clamping plates, are also implemented in order to maintain the clamping of the stack by the clamping plates.

The electrochemical device 100 is generally referred to by one or other of the acronyms "SOEC" ("Solid Oxide Electrolyser Cell") or "SOFC" ("Solid Oxide Full Cell") when it operates, respectively, in electrolyser mode or in fuel cell mode.

The stack 200, as illustrated in FIG. 2, comprises a stack 200 of elementary electrochemical cells 210 between which are interposed interconnectors 230 intended to ensure electrical contact between the elementary electrochemical cells. These interconnectors also comprise channels allowing the evacuation and/or the distribution of gas at the level of the elementary cells.

Each elementary electrochemical cell comprises an electrolyte 210e interposed between an anode 210a and a cathode 210c.

Throughout the description of the present application, by "anode", "cathode" and "electrolyte" is meant elements of generally planar shape, for example in the form of a layer, which comprise two essentially parallel main faces and connected by an outline.

The anode and the cathode of each elementary electrochemical cell generally comprise a porous layer, while the electrolyte forms a dense and tight layer.

Each interconnector disposed on either side of an electrochemical cell forms, respectively, with the anode an anode compartment 230a for gas distribution and collection, and with the cathode a cathode compartment 230c for gas distribution and collection.

In operation, the anode and the cathode are the site of electrochemical reactions, while the electrolyte allows the transport of ions from the cathode to the anode, or vice versa depending on whether the electrochemical device operates in electrolyser mode or in battery mode. fuel.

Thus in electrolyser mode, the cathode compartment allows a supply of water vapor and an evacuation of the water reduction products, in particular hydrogen, while the anode compartment ensures, via a draining gas, the evacuation of the dioxygen produced from the oxidation of O ^2- ions migrating from the cathode to the anode.

The electrolysis mechanism (“SOEC” mode) of water vapor by an elementary electrochemical cell is illustrated in figure 3. During this electrolysis, the elementary electrochemical cell is powered by a current flowing from the cathode to the 'anode. The water vapor distributed by the cathode compartment is then reduced under the effect of the current according to the following half-reaction: [Chem

The dihydrogen produced during this reaction is then evacuated, while the O ^2- ions produced during this reduction migrate from the cathode to the anode, via the electrolyte, where they are oxidized to dioxygen according to the half-reaction: [ Chem

The oxygen thus formed is evacuated by the draining gas circulating in the anode compartment.

Electrolysis of water vapor responds to the following reaction: [Chem 3] 2 H ₂ O -> 2 H ₂ + O ₂ .

In fuel cell (“SOFC”) mode, air is injected into the cathode compartment where the oxygen is then reduced to O ^2- ions. These O ^2- ions then migrate towards the anode and react with dihydrogen circulating in the anode compartment to form water.

Operation in fuel cell mode allows the production of an electric current.

The optimization of the operation of such an electrochemical device known from the state of the art may however require certain constraints.

In particular, it is necessary to have an electrical insulation between two successive interconnectors under penalty of short-circuiting the elementary electrochemical cell. Good electrical contact and a sufficient contact surface between an elementary electrochemical cell and an interconnector may also be necessary. The lowest possible ohmic resistance is then sought between cells and interconnectors. This depends on the facing materials but also on the level of tightness of the stack.

Furthermore, it is necessary to have a seal between the anode and cathode compartments under penalty of having a recombination of the gases produced resulting in a drop in yield and especially the appearance of hot spots damaging the stack. Again, this tightness depends on the design of the seals and the materials used, but also on the level of tightness of the stack. Finally, it is preferable to have a good distribution of the gases both at the inlet and at the recovery of the products, under penalty of loss of yield, of inhomogeneity of pressure and temperature within the various elementary electrochemical cells, even of prohibitive degradations. of said cells.

The electrochemical device 100 as represented in FIG. 1, by a choice of materials forming the rods and the clamping plates, makes it possible to respond favorably to the aforementioned requirements as long as the stack 200 contains less than 25 elementary electrochemical cells. However, when the stack comprises a number of elementary electrochemical cells exceeding 25, the latter is liable to exhibit an expansion at high temperature which is difficult to predict, and consequently makes the dimensioning of the rods and clamping plates complicated.

The object of the invention is therefore to propose a clamping device for clamping an electrochemical stack making it possible to accommodate a large number, for example greater than 25, of elementary electrochemical cells.

Another object of the invention is to provide a clamping device whose expansion remains limited when it is subjected to high temperatures and in particular temperatures above 700° C.

The invention also aims to propose an assembly which comprises the clamping device and an electrochemical stack.

DISCLOSURE OF THE INVENTION

The aims are, at least in part, achieved by a clamping device for an electrochemical stack, said device comprises:

- two clamping plates called, respectively, upper clamping plate and lower clamping plate, facing each other by one of their faces, called, respectively, upper internal face and lower internal face, and between which is intended to be enclosed in an electrochemical stack;

- at least one coil spring arranged to clamp the two clamping plates against an electrochemical stack capable of being clamped between said clamping plates, said at least one coil spring is provided with at least one continuous fluid circulation formed in its volume and which traverses each of the turns of the at least one helical spring;

- At least one holding means intended to maintain the clamping, imposed by the at least one helical spring on the clamping plates.

According to one mode of implementation, the at least fluid circulation channel comprises at least two channels, separated by at least one central core, and which extend parallel and continuously in each of the turns.

According to one mode of implementation, the imprint formed by the at least two channels and the at least one central web along a cutting plane passing through an axis of revolution of the spring, is limited by a circle, the at least a central core comprising two mutually parallel walls.

According to one mode of implementation, the indentations of the two walls along the cutting plane are parallel to the axis of revolution.

According to one embodiment, the at least one fluid circulation channel comprises at least four channels, separated two by two by one of four central cores arranged substantially in the form of a cross in section, and which are 'extend in a parallel and continuous manner in each of the turns.

According to one embodiment, the at least one holding means comprises a base plate, and the at least one helical spring is arranged between the upper clamping plate and the base plate, said base plate being opposite by a internal face with an external upper face of the upper clamping plate and opposite to the internal upper face, the base plate being arranged to impose a compression on the at least one helical spring making it possible to maintain the clamping plates clamped against an electrochemical stack capable of being clamped between said clamping plates.

According to one embodiment, the at least one holding means further comprises at least two tie rods arranged to adjust the distance between the base plate and the lower clamping plate in order to impose compression on the at least one coil spring. According to one mode of implementation, the at least two tie rods are pivotally mounted, by a first end, on a peripheral contour of the lower clamping plate, while the base plate comprises notches intended to be crossed by the tie rods, each tie rod comprises a thread which extends from a second end, opposite the first end and cooperating with a nut.

According to one mode of implementation, the at least one spring comprises a single spring.

According to one mode of implementation, said device comprises as many tie rods as springs, each tie rod passing through openings made in the clamping plates and the base, as well as one of the springs.

According to one mode of implementation, said device further comprises two levers, said respectively, upper lever and lower lever, supported by, respectively, a first upper end and first lower end, against, respectively the upper clamping plate and the lower clamping plate, the helical spring being mechanically linked to one and the other of the levers so that a tensile force of the helical spring translates into a clamping of the clamping plates, by said levers, against an electrochemical stack capable of being clamped between the two clamping plates.

According to one mode of implementation, an intermediate lever is in pivot connection by each of its ends with a second end, opposite the first end, of one and the other of the upper and lower levers.

The invention also relates to an electrochemical assembly which comprises:

- a clamping device according to the present invention,

- an electrochemical stack with solid oxides of the SOEC/SOFC type operating at high temperature and comprising at least one elementary electrochemical cell, said stack being clamped between the upper clamping plate and the lower clamping plate, and so as to exert a force of predetermined crushing on said stack. According to one embodiment, an upper end plate and a lower end plate are inserted between the stack and, respectively, the upper clamping plate and the lower clamping plate.

BRIEF DESCRIPTION OF DRAWINGS

Other characteristics and advantages will appear in the following description of a clamping device, given by way of non-limiting examples, with reference to the appended drawings in which:

[Fig. 1] shows, in a perspective view, an electrochemical device known to the state of the art (document FR 3 045 215), and on which the present invention is likely to be implemented;

[Fig. 2] is an exploded schematic view of a stack of two elementary electrochemical cells known from the state of the art and capable of being implemented within the scope of the present invention;

[Fig. 3] is a schematic view showing the principle of operation of an elementary electrochemical cell in high temperature solid oxide electrolyser (SOEC) mode, the arrows represent the circulation of gases at the level of the electrodes, in particular the arrows in solid lines represent the circulation of reactive gases or reaction products, while the arrow in broken lines represents the circulation of draining gas;

[Fig. 4] is a schematic representation according to a front view of a clamping device clamping an electrochemical stack, according to a first variant of a first embodiment of the present invention;

[Fig. 5] is a schematic representation according to a perspective view of a clamping device clamping an electrochemical stack, according to a second variant of a first embodiment of the present invention;

[Fig. 6] is a schematic representation according to a side view of a clamping device clamping an electrochemical stack, according to a second embodiment of the present invention; [Fig. 7a] is a view along a section plane P passing through the axis of revolution XX' of a helical spring capable of being implemented within the scope of the present invention;

[Fig. 7b] is a detail of the section of the spring of FIG. 7a along the section plane P;

[Fig. 7c] is a variant embodiment of FIG. 7b;

[Fig.8] is a graphical representation of the force (E in N on the vertical axis) exerted by a coil spring as a function of crushing (D in mm, on the horizontal axis) of an electrochemical stack 25 elementary cells;

[Fig. 9a] is a schematic representation according to a front view of a clamping device clamping an electrochemical stack, in particular, in this representation, the tie rods pass through the notches made in the base plate;

[Fig. 9b] is a schematic representation of the clamping device of FIG. 9a according to a perspective view;

[Fig. 10] is a schematic representation in perspective of a one-piece assembly formed by the upper clamping plate, the base plate and the coil spring; and

[Fig. lia] and [Fig. 11b] are schematic representations of two compression phases of an electrochemical stack with the clamping device according to the present invention.

DETAILED DISCUSSION OF PARTICULAR EMBODIMENTS

The present invention relates to a clamping device provided with two clamping plates between which a stack, for example an electrochemical stack, is intended to be clamped. In particular, the device according to the present invention comprises a spring, in particular a helical spring, arranged to transmit a force to the clamping plates, in order to impose crushing on said electrochemical stack. In addition, and in a particularly advantageous manner, the helical spring comprises a conduit for fluid circulation in its volume and which runs through all of the coils of the helical spring. This fluid circulation channel thus allows the circulation of a fluid in the volume of the spring so as to limit, or even prevent, the expansion of the coil spring when it is subjected to high temperatures, and in particular to temperatures above 700°C.

Thus, the clamping device is advantageously implemented in an assembly which comprises an electrochemical stack sandwiched between the two clamping plates.

Figures 4 to 6 illustrate different modes of implementation of a clamping device 400 according to the present invention. In these figures, the clamping device 400 is represented with a stack, and in particular an electrochemical stack 200, clamped between two clamping plates called, respectively, upper clamping plate 410 and lower clamping plate 420.

By "clamping plate" is meant a plate of generally flat shape, which comprises two main faces connected by an outline, and which when they are assembled in pairs are intended to maintain the cohesion of a stack, for example of an electrochemical stack.

“Electrochemical stack” means a stack of elementary electrochemical cells.

The upper clamping plate 410 comprises two main faces called, respectively, upper internal face 410a and an upper external face 410b essentially parallel and connected by an upper contour 410c.

The lower clamping plate 420 comprises two main faces called, respectively, lower internal face 420a and a lower external face 420b essentially parallel and connected by a lower contour 420c.

The upper clamping plate 410 and the lower clamping plate 420 are in particular arranged so that the upper internal face 410a and the lower internal face 420a face each other.

The space delimited by the upper internal face 410a and the lower internal face 420a is intended to accommodate the stack, and more particularly the electrochemical stack 200.

Clamping device 400 also includes at least one coil spring 500. In particular, clamping device 400 may include a single coil spring 500 (Figures 4 and 6), or a plurality of coil springs, for example 4 coil springs 500a, 500b, 500c, 500d, (Figure 5). In particular, the at least one helical spring 500 or 500a, 500b, 500c, 500d is arranged to exert a force which leads to the clamping of the electrochemical stack 200 by the upper clamping plate 410 and the lower clamping plate 420.

By "helical spring" is meant a coil wound in a helix. More particularly, the propeller is part of a cylinder of revolution which includes an axis of revolution XX'. Thus, throughout the description, the axis of revolution XX' of the cylinder is also assimilated to the axis of revolution XX' of the helical spring.

Finally, the at least one coil spring 500 or 500a, 500b, 500c, 500d comprises at least one fluid circulation channel 510 (FIGS. 7a and 7b). This at least one fluid circulation channel 510 is notably formed in the volume of the helical spring. The at least one fluid circulation channel 510 is, moreover, continuous and thus runs through all of the turns of the at least one helical spring 500 or 500a, 500b, 500c, 500d. This arrangement thus makes it possible to impose the circulation of a fluid, from a first end 512a towards a second end 512b of the helical spring 500 in the at least one fluid circulation channel 510 for the purpose of thermalizing said helical spring (figure 4).

In a particularly advantageous manner, it is possible to impose the circulation of a cooling fluid in the at least one fluid circulation channel 510. The circulation of the cooling fluid can in particular be adapted to maintain the helical spring in a range of temperatures for which the mechanical properties undergo little or no variation. In other words, the circulation of a cooling fluid in the at least one fluidic circulation channel 510 makes it possible to limit the variation of the force exerted by the helical spring when the latter is close to a source. heat. In this respect, an electrochemical stack 200 with solid oxides of the SOEC/SOFC type is known to operate at high temperature, and in particular at temperatures above 700° C., and can, consequently, generate heating, by radiation or by conduction, of the coil spring. This heating, source of expansion of the spring helical, without other precautions, generally results in a variation of the force exerted by the latter which ultimately risks causing a rupture of the seal within the electrochemical stack. The implementation of a thermalization of the helical spring by circulation of a cooling fluid thus makes it possible to limit the risk of rupture of the seal.

The at least one helical spring can advantageously comprise at least one of the alloys chosen from: 310s, Inconel 718, Inconel 625.

In this regard, Inconel 718 exhibits corrosion resistance and mechanical properties over a wide temperature range that make it the alloy of choice when the applications under consideration involve temperatures up to 700°C.

According to the terms of the present invention, it may be envisaged to consider at least one fluid circulation channel 510 which comprises two channels 510a and 510b, separated by a central core 510c (FIGS. 7a and 7b). The two channels 510a and 510b extend parallel and continuously in each of the turns.

Advantageously, the two channels 510a and 510b can have essentially identical geometric and dimensional characteristics.

The central core 510c can comprise two parallel walls 511a and 511b each delimiting, and in part, one and the other of the channels 510a and 510b. In this respect, the intersection of the walls 511a and 511b with a section plane P passing through the axis of revolution XX' comprises two segments parallel with said axis of revolution XX'. This orientation of the walls 511a and 511b makes it possible to stiffen the coil spring.

Finally, and still advantageously, the intersection of the assembly formed by the two channels 510a, 510b and the central web 510c with the cutting plane P can be delimited by a circle C (FIG. 7b). In other words, the imprint of each channel 510a and 510b along the section plane is partly delimited by a section of the circle C and by the imprint of one of the walls 511a and 511b along this same section plane.

FIG. 7c illustrates an alternative embodiment of FIG. 7b. In particular, in this example, four channels 510a, 510b, 510d, 510e are formed, which are separated two by two by one of four central cores 510c, 510f, 510g, 510h arranged substantially in the form of a cross in section.

More specifically, channels 510a and 510b are separated by a first core 510c, channels 510d and 510e are separated by a second core 510f, channels 510b and 510e are separated by a third core 510g and channels 510a and 510d are separated by a fourth soul 510h. In this way, the stiffness of the coil spring is further improved, both in the axial direction and in the longitudinal direction.

Moreover, such a geometric configuration can also make it possible to form a heat exchanger. For example, it is possible to circulate a hot outgoing flow in the diagonally opposite channels 510a and 510e and a cold incoming flow in the other diagonally opposite channels 510b and 510d.

Such a coil spring can be formed by an additive manufacturing technique, and in particular by 3D manufacturing.

By way of non-limiting example, the helical spring is formed of an Inconel 718 coil with a diameter, called the outer diameter, equal to 18 mm. The diameter of the circle C can be equal to 10 mm, while the distance between the walls 511a and 511b (in a direction perpendicular to the axis of revolution XX') can be equal to 4 mm.

The force E (in N on the vertical axis) exerted by such a coil spring as a function of crushing D (in mm, on the horizontal axis) of an electrochemical stack of 25 elementary cells is represented graphically in figure 8. On this graph, it appears that a crushing D of 50 mm of the electrochemical stack is associated with a force exerted by the helical spring of 2000 N. This stack, when it is subjected to heating, in particular a heating to a temperature equal to 900°C, is liable to undergo an expansion of approximately 2 mm which results in a negligible variation in the force actually exerted by the helical spring.

The clamping device 400 also comprises at least one holding means 600 intended to maintain the clamping imposed by the at least one helical spring on the clamping plates. FIG. 4 illustrates in this respect a first variant of a first embodiment of the holding means 600 according to the present invention.

In particular, the holding means 600 according to this first variant comprises at least two tie rods 610a and 610b, as well as a base plate 620. The base plate 620 is provided with two main faces called, respectively, internal face 620a and external face 620b and connected by an outline 620c. More particularly, the base plate 620 is facing the upper outer face 410b by its inner face 620a, and the coil spring 500 is located between the base plate 620 and the upper clamping plate 410, resting, respectively, against the face internal 620a and the upper external face 410b.

Furthermore, the at least two tie rods 610a and 610b extend between the lower clamping plate and the base plate to allow said plates to be assembled and to adjust the distance which separates them. More particularly, this adjustment of the distance between the lower clamping plate and the base plate is intended to compress the coil spring 500 so that the latter exerts a force which results in the clamping of the electrochemical stack between the plates clamps 410 and 420.

The at least two tie rods 610a and 610b can, according to a first aspect, pass through through openings made in these two plates and cooperate with clamping means, for example nuts, at the through openings.

According to a second aspect, the at least two tie rods 610a and 610b can advantageously be pivotally mounted, via a first end, on the contour 420c of the lower clamping plate 420 (FIGS. 4, 9a and 9b). According to this second aspect, the base plate 620 comprises notches 612a and 612b intended to be crossed by the tie rods 610a and 610b. Like the first aspect, clamping means, for example nuts, cooperate with the at least two tie rods at the notches 612a and 612b.

Still according to the first variant of this first embodiment, the base plate 620, the upper clamping plate 410 and the coil spring 500 can form a single piece. This one-piece piece can be obtained by a additive manufacturing process, and in particular by 3D manufacturing (figure 10). Advantageously, the first end 512a emerges from the upper clamping plate 510 at the contour 510c, while the second end 512b emerges from the base plate 620 at the contour 620c. According to this arrangement, a fluid, and in particular a cooling fluid, can circulate in the at least one fluid circulation channel 510 of the helical spring 500, from the first end 512a towards the second end 5412b. During this circulation, the cooling fluid, for example water, undergoes heating capable of transforming it into steam into steam. This water vapor can advantageously be injected into the electrochemical stack or into any other system such as a turbine for example.

In a particularly advantageous manner, the base plate comprises an orifice, called mounting orifice 630, in alignment with the axis of revolution XX' of the helical spring 500. This mounting orifice is in particular implemented for the crushing of the electrochemical stack 200.

In this regard, Figures 11a and 11b are illustrations of the assembly of an electrochemical stack 200 and the clamping device.

This assembly comprises, initially, a phase of compression of the electrochemical stack 200 placed between the two clamping plates 410 and 420. apply a force, for example 2000 N, against the upper outer face 410b so as to crush the electrochemical stack 200 (FIG. 11a). This compression phase may involve thermal cycles. For example, the compression may initially take place at room temperature or at a temperature below 200°C. The assembly thus compressed can be heated, for example to a temperature above 700° C., then cooled to its initial temperature while maintaining the force exerted by the jack.

The assembly also includes a second phase during which the tie rods 610a and 610b are positioned in the notches 612a and 612b so as to assemble the lower clamping plate 420 with the base plate 620. This second phase also includes the positioning of nuts 611a and 611b cooperating with the tie rods 610a and 610b at the upper outer face 610b so that the coil spring 500 applies the force initially exerted by the cylinder.

The clamping device 400 according to the present invention thus makes it possible to exert a constant force on the electrochemical stack independently of the temperature of said stack. This device also makes it possible to envisage the stacking of a relatively large number, in particular greater than 25 or even greater than 50, of elementary electrochemical cells.

Furthermore, the cooling liquid circulating in the fluid circulation channel may comprise water. The latter, released in the form of water vapor at the level of the second end of the spring, can advantageously not be upgraded, and in particular be injected into the electrochemical stack as a reagent. This aspect contributes to improving the energy efficiency of the electrochemical stack.

Finally, this clamping device remains relatively compact.

The invention also relates to a second variant of this first embodiment (FIG. 5).

According to this second variant, the clamping device 400 comprises 4 helical springs 500a, 500b, 500c, 500d.

The clamping device 400 also comprises 4 tie rods 610a, 610b, 610c and 610d which each pass through and in order, through through openings, the lower clamping plate 420, the upper clamping plate 410 and the base plate 620. base plate 620 according to this variant can take the form of a spider. Furthermore, each coil spring 500a, 500b, 500c, 500d, disposed between the upper clamping plate 410 and the base plate 620, is also traversed coaxially by one of the tie rods 610a, 610b, 610c and 610d.

The invention also relates to a second embodiment (FIG. 6).

According to this second embodiment, the coil spring 500 no longer operates in compression but in tension and is offset laterally.

The clamping device 400 according to this second embodiment further comprises two levers, said respectively, upper lever 900a and lower lever 900b, supported by, respectively, a first upper end 901a and first lower end 901b, against, respectively the upper clamping plate 410 and the lower clamping plate 420.

The helical spring 500 is mechanically linked to one and the other of the levers 900a and 900b so that a tensile force of the helical spring results in a clamping of the clamping plates 410 and 420, by said levers, against a electrochemical stack 200.

An intermediate lever 900c in pivot connection via each of its ends with a second end 902a and 902b, opposite the first end 901a and 901b, of one and the other of the upper 900a and lower 900b levers can also be considered.

The invention also relates to an electrochemical assembly which comprises:

- a clamping device 400 according to any one of the embodiments of the present invention,

- an electrochemical stack 200 with solid oxides of the SOEC/SOFC type operating at high temperature and comprising at least one elementary electrochemical cell, said stack being clamped between the upper clamping plate and the lower clamping plate, and so as to exert a force predetermined crush on said stack.

The assembly can also comprise an upper end plate 240b and a lower end plate 240a which are inserted between the electrochemical stack 200 and, respectively, the upper clamping plate 410 and the lower clamping plate 420.

Claims

1. Clamping device (400) for an electrochemical stack (200), said device comprises:

- two clamping plates (410, 420) called, respectively, upper clamping plate (410) and lower clamping plate (420), facing each other by one of their faces, called, respectively, face upper internal face (420a) and lower internal face (420b), and between which an electrochemical stack (200) is intended to be clamped;

- at least one helical spring (500, 500a, 500b, 500c, 500d) arranged to clamp the two clamping plates (410, 420) against an electrochemical stack (200) capable of being clamped between said clamping plates (410, 420), said at least one helical spring (500, 500a, 500b, 500c, 500d) is provided with at least one continuous fluid circulation channel (510, 510a, 510b), formed in its volume, and which runs through each of the turns of the at least one coil spring (500, 500a, 500b, 500c, 500d);

- at least one holding means intended to maintain the clamping, imposed by the at least one coil spring (500, 500a, 500b, 500c, 500d) to the clamping plates (410, 420), in which the at least one fluid circulation channel (510, 510a, 510b) comprises at least two channels (510a, 510b), separated by at least one central core (510c), and which extend parallel and continuously in each of the turns.

2. Device according to claim 1, wherein the cavity formed by the at least two channels (510a, 510b) and the at least one central web (510c) along a cutting plane passing through an axis of revolution of the coil spring , is limited by a circle, the at least one central core (510c) comprising two walls (511a, 511b) parallel to each other.

3. Device according to claim 2, wherein the cavities of the two walls (511a, 511b) along the cutting plane are parallel to the axis of revolution.

4. Device according to one of claims 1 to 3, wherein the at least one fluid circulation channel comprises at least four channels (510a, 510b, 510d, 510e), separated in pairs by one of four cores centers (510c, 510f, 510g, 510h) arranged substantially in the form of a cross in section, and which extend parallel and continuously in each of the turns

5. Device according to one of claims 1 to 4, wherein the at least one holding means comprises a base plate (620) provided with a face, called internal face, and facing an upper external face ( 410b) of the upper clamping plate (410), and opposite the upper inner face (420a), the at least one coil spring (500, 500a, 500b, 500c, 500d) being disposed between the upper clamping plate ( 410) and the base plate (620), so that a compression of the coil spring (500, 500a, 500b, 500c, 500d) imposed by the base plate (620) makes it possible to maintain the clamping plates (410, 420) clamped against an electrochemical stack (200) capable of being clamped between said clamping plates (410, 420).

6. Device according to claim 5, wherein the at least one holding means further comprises at least two tie rods arranged to adjust the distance between the base plate (620) and the lower clamping plate (420) in order to impose compression to the at least one coil spring (500, 500a, 500b, 500c, 500d).

7. Device according to claim 6, wherein the at least two tie rods (610a, 610b) are pivotally mounted, by a first end, on a peripheral contour (420c) of the lower clamping plate (420), while the plate base (620) comprises notches (612a, 612b) intended to be traversed by the tie rods (610a, 610b), each tie rod (610a, 610b) comprises a thread which extends from a second end, opposite the first end and cooperating with a nut. 19

8. Device according to claim 7, wherein the at least one coil spring comprises a single coil spring (500).

9. Device according to claim 6, wherein said device comprises as many tie rods (610a, 610b) as coil springs, each tie rod being associated with a given coil spring, and passes through openings made in the clamping plates (410, 420 ) and the base plate, as well as the coil spring to which it is associated.

10. Device according to one of claims 1 to 4, wherein said device further comprises two levers (900a, 900b), said respectively, upper lever (900a) and lower lever (900b), supported by, respectively, a first upper end and first lower end against the upper clamping plate (410) and the lower clamping plate (420), respectively, the coil spring (500) being mechanically linked to one and the other of the levers so that a tensile force of the helical spring (500) results in a clamping of the clamping plates (410, 420), by said levers, against an electrochemical stack (200) capable of being clamped between the two clamping plates ( 410, 420).

11. Clamping device according to claim 10, wherein an intermediate lever is in pivot connection by each of its ends with a second end, opposite the first end, of one and the other of the upper and lower levers.

12. Electrochemical assembly which includes:

- a clamping device according to one of claims 1 to 11,

- an electrochemical stack (200) with solid oxides of the SOEC/SOFC type operating at high temperature and comprising at least one elementary electrochemical cell, said stack being clamped between the upper clamping plate (410) 20 and the lower clamping plate (420), and so as to exert a predetermined crushing force on said stack.

13. Assembly according to claim 12, in which an upper end plate and a lower end plate are inserted between the stack and, respectively, the upper clamping plate (410) and the lower clamping plate (420).