Device for protecting against thermal runaway in a battery

Abstract

A battery (1) is disclosed that comprises: - at least two electrochemical elements (2-1, 2-2) of parallelepipedal format, - a first layer (3-1) of a refractory material resistant to a temperature up to 1200°C placed in contact with the entirety of a first face that is one of the faces (4) of largest area of one (2-1) of the electrochemical elements, said first layer comprising a central region (C) having as centre the centre of the first layer and having an area representing from 30 to 60% of the area of said first face; - a rigid spacer (5) having a hardness higher than or equal to 90 Shore A according to standard ASTM D 2240-15(2021), placed between said first layer and the second electrochemical element (2-2), the rigid spacer being located outside of the central region of said first layer.

Description

Description Title: Protection device against the propagation of thermal runaway in a battery Technical field of the invention

[0001] The invention relates to the technical field of devices for protection against the propagation of thermal runaway in a battery of electrochemical elements. Context of the invention

[0002] An electrochemical cell battery comprises a plurality of electrochemical cells, hereafter referred to as "cell(s)," which are assembled side by side in a common grouping case. This case is designed to hold the cells in a fixed position during transport or use of the battery.

[0003] During the charging of a hermetically sealed lithium-ion cell, the cell container swells. In the case of a rectangular (or prismatic) cell, this swelling occurs primarily on the two largest opposing flat lateral faces of the container. This swell increases as the cell's state of charge approaches full charge. Because the cells are stacked end-to-end in the battery compartment, and each cell experiences an increase in thickness, there is a significant increase in the total battery length resulting from the sum of the increases in cell thickness.However, since the bulkhead container is generally made of a rigid material and the free space between the components and the container walls is limited, the swelling of the components subjects the container walls to pressure forces that can lead to irreversible deformation or even damage. Therefore, a device is often used to prevent the container from deforming due to the swelling of the components during loading.

[0004] Furthermore, an anomaly in the operation of the battery can be caused by the malfunction of one of the elements (short circuit, overload, etc.) or by an external disturbance (shock, temperature rise, etc.) or even by a failure of the electronic system managing the state of charge or other parameters of the battery elements.

[0005] For example, when a lithium battery is subjected to an overload, its temperature rises. This temperature increase leads to an increase in the charging current, which further increases the temperature. If the battery does not have a sufficient cooling system to dissipate the emitted heat, it will experience thermal runaway: the temperature increase is fueled by... The uncontrolled increase in the cell's temperature leads to the generation of gases, which can cause an increase in the cell's internal pressure, triggering a gas venting system. If hot gases, reaching temperatures of up to 650°C, are released, they come into contact with other battery cells. There is then a risk that thermal runaway will spread to all the battery cells, leading to the total destruction of the battery.

[0006] We are therefore looking for a device that prevents the trunk from deforming under the effect of the swelling of the elements during their charging and that also prevents the propagation of a thermal runaway between the battery elements.

[0007] Document EP-A-3 208 866 describes a system for compensating for cell swelling in a battery. This system comprises a rigid spacer and a flexible spacer placed between two adjacent cells. The rigid spacer can be positioned around the periphery of the largest face of the cells. Its function is to maintain a constant distance between the two adjacent cells. The flexible spacer can be positioned near the center of the largest face of the cells. Its function is to absorb the increase in thickness of the two cells during charging. As shown in Figure 2b of this document, this system maintains a constant battery length in the event of cell swelling. In a preferred embodiment, the flexible spacer is made of a material with low thermal conductivity. This has the advantage of preventing the heat generated by this element from propagating to neighboring cells.To improve safety, there is a need for the inter-element spacer to withstand very high temperatures.

[0008] Document EP-A-2 994 947 describes a battery comprising a first and a second prismatic element separated by a layer of material resistant to a temperature of 300°C. This material is not in contact with the entire external wall surface of the container holding the two elements. Two spacers placed between the containers of the two elements at their upper and lower ends maintain the 300°C-resistant material at a certain distance from the wall of the element container. The combination of the 300°C-resistant material layer and the two spacers is presented as constituting a thermal barrier against the propagation of a thermal runaway. However, this solution is not entirely satisfactory because the 300°C-resistant material layer is not in contact with the wall of the element container.There are two layers of air on either side of the layer of material resistant to a temperature of 300°C. On the one hand, these air layers can facilitate the propagation of heat to neighboring elements. On the other hand, they increase the length of the battery. The fact that the... The fact that the material resistant to a temperature of 300°C is not in contact with the entire surface of the elements prevents its thermal barrier properties from being fully utilized. Furthermore, when the elements expand, the layer of the material resistant to 300°C tends to compress under the force exerted by the elements. It therefore performs its insulating function less effectively. Finally, it is recommended to use spacers with a degree of flexibility to conform to the shape of the element surfaces. Because the layer of the material resistant to 300°C and the spacers tend to compress under the force of the elements, the distance between the terminals of two adjacent elements decreases. The electrical connection between two adjacent elements must therefore be flexible to accommodate the variation in the inter-element distance.However, such flexible connections are more complex in design than rigid connections in the form of simple metal bars.

[0009] US patent 9,324,982 describes a system for compensating for the expansion of cells in a battery and ensuring their cooling. A barrier is placed between two cells. It consists of an outer part in contact with the periphery of the largest surface area of ​​the cells and an inner part in contact with the center of the largest surface area of ​​the cells. The outer part is rigid and maintains a constant spacing between two adjacent cells. The inner part is flexible and absorbs the increase in volume of the two adjacent cells. The opposite faces of the outer and inner parts are covered with truncated pyramid-shaped studs. The cells are cooled by the circulation of air between the studs. The disadvantage of the studs is that they increase the length of the battery.The presence of air circulation channels is also undesirable, as they can contribute to the propagation of thermal runaway. Furthermore, the battery casing must have openings to allow air to enter and exit. Finally, the contact area between a cell and the barrier is relatively small, limited to the truncated upper surface of the studs. As with the previous document, this cell swelling compensation system reduces heat transfer within the battery when it is used under nominal operating conditions. However, it is not designed to prevent the propagation of thermal runaway from one cell to a neighboring cell.

[0010] Therefore, there remains a need for a system to compensate for the swelling of the elements which also prevents the propagation of thermal runaway between the elements. Summary of the invention

[0011] To this end, the invention proposes a battery comprising: - at least two electrochemical elements in parallelepiped format, - a first layer of a refractory material resistant to a temperature up to 1200°C disposed in contact with the entirety of a first face which is one of the faces with the largest area of ​​one of the electrochemical elements, said first layer comprising a central region having as its center the center of the first layer and having an area representing 30 to 60% of the area of ​​said first face; - a rigid shim having a hardness greater than or equal to 90 Shore A according to ASTM D 2240-15(2021), disposed between said first layer and the second electrochemical element, the rigid shim being located outside the central region of said first layer.

[0012] On the one hand, the placement of a layer of refractory material in contact with the entire surface area of ​​one of the elements makes it possible to create a thermal barrier preventing the propagation of a thermal runaway from this element to neighboring elements.

[0013] On the other hand, placing a rigid wedge outside the central region of the refractory material layer ensures that this central region is not compressed by the elements during their swelling and therefore retains its function as a thermal barrier.

[0014] According to one embodiment, the battery comprises a second layer of a refractory material resistant to a temperature up to 1200°C, this second layer being disposed between the rigid wedge and the second electrochemical element and being in contact with the whole of a second face which is one of the faces with the largest area of ​​the second electrochemical element, said second layer comprising a central region having as its center the center of said second layer and having an area representing 30 to 60% of the area of ​​said second face.

[0015] According to one embodiment, the refractory material of the first layer and / or the second layer is compressible so that its thickness can be reduced by at least 50% or at least 70% or at least 80% under the effect of compression exerted by the two electrochemical elements.

[0016] According to one embodiment, the refractory material of the first layer and / or the second layer is compressible so that its thickness can be reduced up to 95% under the effect of compression exerted by the two electrochemical elements.

[0017] According to one embodiment, the refractory material of the first layer and / or the second layer is a sheet comprising ceramic fibers.

[0018] According to one embodiment, the refractory material of the first layer and / or the second layer has a thermal conductivity at 20°C less than or equal to 0.5 W / (mK).

[0019] According to one embodiment, the rigid wedge is made of a stable plastic material chemically up to a temperature of 200°C.

[0020] According to one embodiment, the rigid wedge is made of a material selected from the group consisting of polytetrafluoroethylene (PTFE), polyimide (PI) and polyepoxide (PE).

[0021] According to one embodiment, the rigid wedge comprises four uprights forming a first rectangular frame.

[0022] According to one embodiment, the rigid wedge further comprises four other uprights forming a second rectangular frame of greater height and width than the first rectangular frame.

[0023] According to one embodiment, - the first layer and / or the second layer has a height and a width, and - the height and width of the second frame correspond to the height and width of the first layer and / or the second layer.

[0024] According to one embodiment, the first and second rectangular frames are joined together by means of at least two connecting elements.

[0025] According to one embodiment, the battery comprises six connecting elements, two connecting elements each linking a horizontal upright of the first frame to a horizontal upright of the second frame, four connecting elements each linking a corner of the first frame to a corner of the second frame.

[0026] According to one embodiment, the two ends of the connecting elements have reinforcements to stiffen the connection of the first frame to the second frame.

[0027] According to one embodiment, the thickness of a post ranges from 0.5 to 1.5 mm, preferably from 0.7 to 1 mm.

[0028] According to one embodiment, an assembly means allows the first layer of refractory material to be joined to the rigid wedge.

[0029] According to one embodiment, an assembly means makes it possible to secure the first layer of refractory material with the rigid wedge and with the second layer of refractory material.

[0030] The invention also relates to a method for assembling the battery as described above. Said method comprises the steps of: a) providing a first electrochemical element in parallelepiped format, b) placing a first layer of a refractory material resistant to a temperature up to 1200°C in contact with the entirety of a first face which is one of the faces with the largest area of ​​one of the electrochemical elements, said first layer having a central region having as its center the center of the first layer and an area representing 30 to 60% of the area of ​​the first face; c) placing a rigid spacer having a hardness greater than or equal to 90 Shore A according to ASTM D 2240-15(2021), against the first layer, the rigid spacer being located outside the central region of said first layer; d) adherence against the rigid wedge of a second face which is one of the faces with the largest area of ​​the second electrochemical element in parallelepiped format.

[0031] According to one embodiment, the process includes, between step c) and step d), the placement of a second layer of a refractory material resistant to a temperature up to 1200°C, said second layer comprising a central region having as its center the center of the second layer and an area representing 30 to 60% of the area of ​​the second face, the second layer being in contact with the entirety of the second face.

[0032] According to one embodiment, the process includes, after step d), a step of compressing said at least two electrochemical elements by means of a belt or armature or strap or frame around the elements. Brief description of the drawings

[0033] Embodiments of the invention are described below in more detail with reference to the accompanying drawings.

[0034] [Fig.1] is a schematic cross-sectional view of a battery comprising two electrochemical elements separated by a layer of refractory material and a rigid wedge.

[0035] [Fig.2] is a schematic cross-sectional view of a battery comprising two electrochemical elements separated by two layers of refractory material and a rigid wedge, the rigid wedge being sandwiched between the two layers of refractory material.

[0036] [Fig.3] shows a top view of an assembly consisting of a layer of refractory material on which a rigid wedge is placed. Description of the embodiments of the invention

[0037] The container for the elements is rectangular in shape. It has six faces: a top face, a bottom face, and four lateral faces. The bottom face is the one in contact with the support on which the element rests. Two of the six faces are parallel and have the largest surface area. These two faces with the largest surface area are generally the most prone to swelling. Preferably, the two faces with the largest surface area are oriented perpendicular to the support on which the element rests.

[0038] For the two faces of the container with the largest surface area, we define a central region and a peripheral region. The central region undergoes greater swelling than the peripheral region. The central region is centered on the center of the face in question and extends over an area representing 30 to 60% or 40 to 50% of the surface area of ​​the container face. The peripheral region is the area extending beyond the central region.

[0039] The first layer of refractory material is placed against one of the container's faces with the largest surface area. Generally, the height and width of the first layer of refractory material correspond to the height and width of the... The largest surface area of ​​the container is defined as the first layer of refractory material. This first layer is divided into a central region and a peripheral region. The central region is centered on the first layer and extends over an area representing 30 to 60% or 40 to 50% of the largest surface area of ​​the container face. It is important that the central region of the refractory material layer is not crushed by the compression of the elements. To this end, a rigid spacer is placed outside the central region of the refractory material layer. The rigid spacer ensures that there is no compression of the refractory material layer in the central region. It also guarantees that the thickness of the refractory material layer is at least equal to a given thickness, which is equal to the thickness of the rigid spacer.

[0040] It is possible to use one, two, or even more layers of refractory material between the elements. The refractory material can be highly compressible, meaning that under compression, its thickness can be reduced by at least 50%, 70%, or 80%. Its thickness can be reduced by up to approximately 95%.

[0041] The refractory material withstands temperatures of at least 1200 °C. It can be a sheet containing ceramic fibers, that is, artificial vitreous (silicate) fibers with a random orientation and a weight percentage of alkali and alkaline earth oxides: [Na₂O] + [K₂O] + [CaO] + [MgO] + [BaO] of less than 18%. These fibers are made from silica / alumina mixtures or from kaolinite. Other oxides such as zirconia, boron, or titanium oxides can be added. Ceramic fibers are highly compressible. They act like a spring. The thickness of the sheet containing ceramic fibers therefore adapts to the distance between two elements. The sheet containing ceramic fibers compensates for slight variations in the dimensions of the elements that might occur during their manufacture. This allows the use of a single size of battery pack.

[0042] In addition to its ability to withstand high temperatures, refractory material can also act as a good thermal insulator, preventing heat generated by a malfunctioning component from spreading to neighboring components. Refractory material can have a thermal conductivity at 20°C of less than 0.5 W / (mK), preferably ranging from 0.02 to 0.2 W / (mK).

[0043] The rigid spacer is made of a material with a hardness of 90 Shore A or greater, according to ASTM D 2240-15(2021). Its rigidity maintains a constant gap between two adjacent elements. Without a rigid spacer, the swelling of two adjacent elements would lead to the almost complete crushing of the refractory material layer along its entire height. The thickness of the refractory material layer could, in fact, be reduced to only 5% of its original thickness before compression. At such a low thickness, the refractory material layer would be virtually ineffective as a thermal barrier. Thanks to this invention, the refractory material layer is reduced only to the location of the rigid wedge, that is, only in the peripheral region. Because the refractory material layer is in contact with almost the entire height of the element, a highly effective thermal barrier is achieved.

[0044] The material used for the rigid spacer preferably withstands a temperature of at least 200°C. Preferably, it is a non-conductive material (such as plastic). Even more preferably, it is polytetrafluoroethylene (PTFE), polyimide (PI), or polyepoxide (PE). The thickness of the rigid spacer is not limited. It is chosen by an operator based on the desired spacing between the elements and the minimum required thickness of the refractory material layer. It can range from 0.5 to 1.5 mm, preferably from 0.7 to 1 mm. The use of a rigid spacer keeps the refractory material uncompressed and maintains a constant spacing between two elements. Thus, the length of the battery does not change during operation.The invention therefore makes it possible to meet the dual requirement of having, on the one hand, a battery that maintains a constant length during its operation, and on the other hand, one that prevents the propagation of thermal runaway between the battery elements.

[0045] Figure 1 schematically represents a first embodiment in which a single layer of refractory material is used. It shows a battery (1) comprising two parallelepiped-shaped electrochemical elements (2-1, 2-2). The container for these elements has an upper face with the positive and negative terminals and a lower face opposite the upper face, which is in contact with a support. The elements are electrically connected by a connecting piece (15). A layer of refractory material (3-1) is arranged between the elements. In this example, the height of the refractory material layer is the same as the height of the elements. One face of the refractory material layer is in contact with one of the largest faces (4-1) of one of the elements (2-1). The contact extends over the entire height of the refractory material layer.The opposite face of the refractory material layer is not completely in contact with one of the largest surface areas (4-2) of the neighboring element (2-2). This is because the rigid spacer (5) of thickness "e" prevents the opposite face of the refractory material layer (3-1) from being completely in contact with the largest surface area (4-2) of the neighboring element (2-2). The central and peripheral regions are represented schematically by the letters C and P, respectively. The two boundaries L1 and L2 between the central region C and the peripheral region P of the containers of the two elements coincide with the boundaries between the central and peripheral regions of the refractory material layer. Note that the rigid spacer is positioned outside the central region. of the central region. The refractory material layer is therefore only compressed in its peripheral region, which is the least prone to swelling. The refractory material layer in its central region is not deformed.

[0046] Figure 2 schematically represents a second embodiment in which two layers (3-1, 3-2) of refractory material are arranged between two elements (2-1, 2-2). This second embodiment is preferable to the first because the two faces (4-1, 4-2) of the two opposing elements are both in complete contact with a layer of refractory material. The thermal barrier effect is therefore improved.

[0047] The rigid wedge preferably has the form of a frame comprising two vertical uprights of height H1 and two horizontal uprights of length L1. The height H1 and the length L1 are determined so that the area of ​​the frame is greater than the area of ​​the central region of the refractory material layer and therefore that once in place between the elements, the rigid wedge is located outside the central region of the refractory material layer.

[0048] To facilitate the placement of the spacer between the elements during battery manufacturing, the frame can be made integral to a second frame with dimensions H2 and L2 greater than H1 and L1. Preferably, the second frame, the layer(s) of refractory material, and the face of the container in contact with a layer of refractory material have the same height and width.

[0049] The first frame is secured to the second frame by means of connecting elements. When the second frame is placed between two electrochemical elements, it aligns with the edge of the electrochemical elements. The first frame is automatically and correctly positioned outside the central region of the refractory material layer.

[0050] The connecting elements linking the first frame to the second frame can be six in number, two connecting elements each linking a horizontal upright of the first frame to a horizontal upright of the second frame, four connecting elements each linking a corner of the first frame to a corner of the second frame.

[0051] The junction area between a connecting element and a post of the first or second frame can be reinforced by locally widening the junction area. This widening can be circular or rectangular in shape.

[0052] The assembly consisting of the first frame, the second frame, the connecting elements, and any reinforcements can be manufactured by molding a plastic part. This results in a single piece that is easy to handle and position.

[0053] The rigid wedge can be integrated into a layer of refractory material. It can also be sandwiched between two layers of refractory material. In both cases, this allows for handling only one piece during assembly.

[0054] Figure 3 is a top view of an assembly consisting of a layer of re- material A fractory element (3-1) is formed on which a rigid wedge is placed. The rigid wedge comprises a first frame with two horizontal uprights (6-1, 6-3) of length L1 and two vertical uprights (6-2, 6-4) of height H1. This first frame is inscribed within a second, larger frame with two horizontal uprights (6-5, 6-7) of length L2 and two vertical uprights (6-6, 6-8) of height H2. The dimensions of the second frame correspond to the dimensions of the refractory material layer, which can itself be cut to the dimensions of the face of the element with which it is in contact. The dimensions H1 and L1 of the first frame are calculated so that it lies outside the central region of the refractory material layer. The first frame is secured to the second frame by means of connecting elements. Two connecting elements (8-1, 8-2) each link a horizontal upright of the first frame to a horizontal upright of the second frame.Four connecting elements (9-1, 9-2, 9-3, 9-4) each link a corner of the first frame to a corner of the second frame. The ends of the connecting elements are fitted with reinforcements (10) which consist of a widening of the junction area between the uprights of the first or second frame and the connecting elements.

[0055] A method for assembling a battery comprising at least two electrochemical elements includes the steps of: a) making available a first electrochemical element in parallelepiped format, b) placing a first layer of a refractory material resistant to a temperature up to 1200°C in contact with the entirety of a first face which is one of the faces with the largest area of ​​one of the electrochemical elements, said first layer having a central region having as its center the center of the first layer and an area representing from 30 to 60% of the area of ​​the first face; c) placing a rigid spacer having a hardness greater than or equal to 90 Shore A according to ASTM D 2240-15(2021) against the first layer, the rigid spacer being located outside the central region of said first layer;d) adherence against the rigid wedge of a second face which is one of the faces with the largest area of ​​the second electrochemical element in parallelepiped format.;

[0056] Preferably, before attaching the second electrochemical element, a second layer of refractory material resistant to a temperature of up to 1200°C is attached to the rigid wedge, said second layer having a central region centered on the center of the second layer and an area representing 30 to 60% of the area of ​​the second face in contact with the entire second face of the second electrochemical element.

[0057] To facilitate the placement of the rigid wedge, a rigid wedge consisting of two frames of different dimensions joined together can be used, the larger frame having a height and width identical to those of the refractory material layer and to those of the container face of the element, as shown in Figure 3. This allows the rigid wedge to be positioned correctly between the two elements automatically.

[0058] Finally, the rigid wedge can be attached to the layer(s) of refractory material to form a single-step assembly placed between the two elements. One side of the layer(s) of refractory material may have an adhesive. One side of the rigid wedge may also have an adhesive. Another method involves using a clamp or clip on the outer frame of the rigid wedge to hold the layer(s) of refractory material in place.

Claims

Demands

1. Battery (1) comprising: - at least two electrochemical elements (2-1, 2-2) of parallelepiped format, - a first layer (3-1) of a refractory material resistant to a temperature up to 1200°C disposed in contact with the whole of a first face which is one of the faces (4) of largest area of ​​one (2-1) of the electrochemical elements, said first layer comprising a central region (C) having as its center the center of the first layer and having an area representing from 30 to 60% of the area of ​​said first face; - a rigid shim (5) having a hardness greater than or equal to 90 Shore A according to ASTM D 2240-15(2021), disposed between said first layer and the second electrochemical element (2-2), the rigid shim being located outside the central region of said first layer.

2. Battery (1) according to claim 1, comprising a second layer (3-2) of a refractory material resistant to a temperature up to 1200°C, this second layer being disposed between the rigid wedge (5) and the second electrochemical element (2-2) and being in contact with the whole of a second face which is one of the faces with the largest area of ​​the second electrochemical element, said second layer comprising a central region (C) having as its center the center of said second layer and having an area representing from 30 to 60% of the area of ​​said second face.

3. Battery (1) according to any one of claims 1 and 2, wherein the refractory material of the first layer (3-1) and / or the second layer (3-2) is compressible so that its thickness can be reduced by at least 50% or at least 70% or at least 80% under the effect of compression exerted by the two electrochemical elements.

4. Battery (1) according to any one of claims 1 to 3, wherein the refractory material of the first layer (3-1) and / or the second layer (3-2) is compressible so that its thickness can be reduced up to 95% under the effect of compression exerted by the two electrochemical elements.

5. Battery (1) according to any one of the preceding claims, wherein the refractory material of the first layer (3-1) and / or the second layer (3-2) is a sheet comprising ceramic fibers.

6. Battery (1) according to any one of the preceding claims, wherein the refractory material of the first layer (3-1) and / or the second layer (3-2) has a thermal conductivity at 20°C less than or equal to 0.5 W / (mK).

7. Battery (1) according to any one of the preceding claims, wherein the rigid wedge (5) is made of a plastic material that is chemically stable up to a temperature of 200°C.

8. Battery (1) according to claim 7, wherein the rigid wedge (5) is made of a material selected from the group consisting of polytetrafluoroethylene (PTFE), polyimide (PI) and polyepoxide (PE).

9. Battery (1) according to any one of the preceding claims, wherein the rigid wedge (5) comprises four uprights (6-1, 6-2, 6-3, 6-4) forming a first rectangular frame.

10. Battery (1) according to claim 9, wherein the rigid wedge (5) further comprises four other uprights (6-5, 6-6, 6-7, 6-8) forming a second rectangular frame of greater height and width than the first rectangular frame.

11. Battery (1) according to claim 10, wherein: - the first layer (3-1) and / or the second layer (3-2) has a height (H) and a width (L), and - the height and width of the second frame correspond to the height and width of the first layer and / or the second layer.

12. Battery (1) according to any one of claims 10 and 11, wherein the first and second rectangular frames are joined together by means of at least two connecting elements (8-1, 8-2).

13. Battery (1) according to claim 12, comprising six connecting elements, two connecting elements (8-1, 8-2) each connecting a horizontal upright of the first frame to a horizontal upright of the second frame, four connecting elements (9-1, 9-2, 9-3, 9-4) each connecting a corner of the first frame to a corner of the second frame.

14. Battery (1) according to any one of claims 12 to 13, wherein both ends of the connecting elements have reinforcements (10) enabling the connection of the first frame to be stiffened to the second frame.

15. Battery (1) according to any one of claims 9 to 14, wherein the thickness (e) of an amount ranges from 0.5 to 1.5 mm, preferably from 0.7 to 1 mm.

16. Battery (1) according to any one of claims 9 to 15, wherein an assembly means makes it possible to secure the first layer (3-1) of refractory material with the rigid wedge (5).

17. Battery (1) according to any one of claims 2 to 15, wherein an assembly means makes it possible to secure the first layer (3-1) of refractory material with the rigid wedge (5) and with the second layer (3-2) of refractory material.

18. Method of assembling a battery (1) comprising at least two electrochemical elements (2-1, 2-2), said method comprising the steps of: a) making available a first electrochemical element (2-1) of parallelepiped format, b) placing a first layer (3-1) of a refractory material resistant to a temperature up to 1200°C in contact with the entirety of a first face which is one of the faces (4) of largest area of ​​one of the electrochemical elements (2-1), said first layer comprising a central region (C) having as its center the center of the first layer and an area representing from 30 to 60% of the area of ​​the first face; (c) placement of a rigid shim (5) having a hardness greater than or equal to 90 Shore A according to ASTM D 2240-15(2021), against the first layer (3-1), the rigid shim being located outside the central region of said first layer;d) adherence against the rigid wedge of a second face which is one of the faces with the largest area of ​​the second electrochemical element (2-2) of parallelepiped format.;

19. Method according to claim 18 comprising between step c) and step d) the placement of a second layer (3-2) of a refractory material resistant to a temperature up to 1200°C, said second layer comprising a central region (C) having as its center the center of the second layer and an area representing 30 to 60% of the area of ​​the second face (3-2), the second layer being in contact with the entirety of the second face.

20. A method according to any one of claims 18 or 19, comprising after step d), a step of compressing said at least two electrochemical elements (2-1, 2-2) by means of a belt or armature or strap or frame around the elements.

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