Electrochemical cells for storing electrical energy

Abstract

An electrochemical cell for an electric energy storage device, particularly intended for motor vehicles, comprising a plurality of electrodes (3) and a compression device (4) adapted to changes in the volume of the plurality of electrodes (3), the compression device (4) comprising a case (5) and an at least partially elastically deformable return element (6) which keeps its various elements in contact with one another and thus enables an appropriate compression to be constantly exerted on the plurality of electrodes (3) in order to enable a more uniform operation of the cell.

Description

Summary of the Invention

[0001] The present invention relates to an electrochemical cell for an electric energy storage device, in particular an electric battery. The invention also relates to an electric energy storage device comprising said cell and to a vehicle comprising such a storage device and / or such a cell. Finally, the invention relates to a method for manufacturing an electrochemical cell.

[0002] In electric or hybrid vehicles, current electric drive means include electric storage devices or electric batteries, which are becoming more and more powerful to compete with the performance level of thermal engines. Increasing the electric drive performance level mainly depends on improving the vehicle's driving range, for example by increasing the volume of the storage device.

[0003] Traditionally, storage devices (also called "battery packs" or more simply "batteries") comprise a number of cells, in particular of the lithium or lithium-ion type, and can be manufactured according to different architectures: the so-called cylindrical and prismatic cells consist of a winding or stack of electrodes that are prefabricated and fitted into a rigid metal housing sealed by a cover.

[0004] During the use cycle of the cell, the electrode windings or stacks show volumetric expansion or contraction during the charge and discharge phases, respectively. The magnitude of this type of volumetric change depends on the active material used. It is maximized, for example, when using silicon technology as the active material of the negative electrode. Furthermore, volumetric expansion of these elements is also observed during the life cycle of the cell, especially with its aging.

[0005] Also, in order to function properly, some types of electrochemical cells require the application of pressure to the electrode windings or stacks to increase the mechanical strength and the contact between the different elements. This pressure is particularly important in the case of cells with solid electrolytes. This pressure also proves necessary in the case of systems that exhibit significant gassing respiration when charging and discharging, and without pressure, as mentioned above for silicon technology, a loss of contact between the materials is observed, affecting the life of the battery.

[0006] Compression devices exist at the level of the module or battery pack, which aim to pressurize the electrochemical cells, for example by means of spring systems or screwed plates. Nevertheless, these solutions are only usable in the case of electrochemical cells with flexible packaging, i.e. "pouch" type electrochemical cells. Nevertheless, these solutions are not compatible with cells with rigid packaging.

[0007] The document US 9634351 discloses an example of an electrochemical cell with a rigid packaging in which the electrode windings are held by a helical return element. The purpose of this type of return element is to facilitate the assembly of the cell by keeping the electrode windings in place, but it does not have a winding compression function corresponding to the life of the cell. In particular, with the volume expansion of the electrode windings, pressure and local mechanical strains are exerted at the interface between the return element and the electrode windings. As this pressure is applied locally, it is highly likely that shearing of the outer elements of the electrode windings will result. In addition, this local pressure variation can lead to local non-uniformity between compressed and non-compressed areas, potentially leading to non-uniformity in the aging of the cell and therefore to a deterioration of the cell's operation.

[0008] The present invention is within this context and aims to overcome the above mentioned drawbacks by proposing an electrochemical cell equipped with a compression device for the electrode windings or stacks, in the case of electrochemical cells with rigid packaging, carrying out this compression within the cell and not at the level of the module or battery pack. This system makes it possible to apply a constant pressure regardless of the charge and aging state of the battery.

[0009] The present invention proposes an electrochemical cell comprising a plurality of electrodes, a compression device for the plurality of electrodes, and a rigid packaging capable of receiving the plurality of electrodes and the compression device, the compression device comprising: - at least one at least partially elastically deformable return element configured to deform between a first configuration and a second configuration based on a volume of the plurality of electrodes, the at least one return element being interposed between the plurality of electrodes and at least a portion of the rigid packaging; - a metal shell comprising one or more parts, the shell being placed between at least one return element and the multiple electrodes, the shell surrounding the multiple electrodes, so as to have at least one overlapping area of ​​two individual parts of the shell, the surface of which varies according to the volume of the multiple electrodes.

[0010] In particular, the at least one return element may comprise a rigid body and a plurality of elastically deformable fins coupled to the body and having an inclination α relative to the body, wherein when the at least one return element is in a first configuration, the value of the inclination α is maximum, so that the plurality of fins extend protruding from the body, and when the at least one return element is in a second configuration, the value of the inclination α is minimum, so that the at least plurality of fins extend in contact with the shell.

[0011] Alternatively, the at least one return element may comprise an "accordion" structure comprising a plurality of folds or elastically deformable folds whose shape and / or angle β varies according to the volume of the plurality of electrodes.

[0012] In particular, the shells can be centered on a principal axis, the smallest surface of the overlap region being derived from the principal axis and defined in a plane perpendicular to the principal axis and bounded by an angular segment of 10 to 30°, in particular 10 to 20°.

[0013] The electrodes can be arranged according to windings around an extension axis and / or according to stacks extending along the extension axis, with at least one return element and / or shell being centered around such an axis.

[0014] According to an exemplary embodiment, the compression device may comprise a plurality of return elements arranged along at least one dimension, in particular the longest dimension, of the plurality of electrodes and / or shell, the plurality of return elements extending across all or a portion of said dimension. The plurality of return elements may comprise a first return element having a central position along a defined dimension and at least one second return element having a more end position along said same dimension, the first return element having a greater stiffness modulus than the at least one second return element.

[0015] Additionally, the electrochemical cell may include an electrically insulating leaf disposed about the plurality of electrodes such that the leaf is interposed between the plurality of electrodes and the shell.

[0016] The invention also relates to an electrical energy storage device, in particular intended for a motor vehicle, comprising at least one electrochemical cell as defined above.

[0017] The invention also relates to a hybrid or electric vehicle comprising at least one electrochemical cell and / or at least one electric energy storage device according to the invention.

[0018] Finally, the present invention relates to a method for producing an electrochemical cell as described above, the method comprising the steps of: - positioning at least one return element on the tool, in particular in a first configuration; - positioning a shell around a plurality of electrodes; - placing the assembly formed by the plurality of electrodes and the shell towards the at least one return element, in particular so that the shell and the at least one return element are concentric; - deforming the at least one return element, during which the return element is displaced by a translational movement relative to the shell, in particular so that the at least one return element encloses the shell and the plurality of electrodes; Next, - inserting the assembly formed by the plurality of electrodes, the shell and the at least one return element into a rigid packaging.

[0019] Other details, features and advantages will become more apparent on reading the detailed description given below with reference to different exemplary embodiments illustrated in an indicative and non-limiting manner in the following drawings, in which: [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is an exploded schematic view of one embodiment of an electrochemical cell according to the present invention. [Diagram 2] FIG. 1 is a schematic perspective view of an electrochemical cell. [Diagram 3] FIG. 1 is a schematic cross-sectional view of an electrochemical cell comprising a return element according to a first embodiment. [Figure 4] FIG. 2 is a perspective view of a return element according to a first embodiment; [Diagram 5] FIG. 4 is a schematic diagram of the electrochemical cell shown in FIG. 3, when the return element is in a first configuration. [Figure 6] FIG. 4 is a schematic diagram of the electrochemical cell shown in FIG. 3, when the return element is in a second configuration. [Figure 7] FIG. 2 is a schematic lateral view of a return element according to the first embodiment; [Figure 8] FIG. 2 is a schematic plan view of the shell of an electrochemical cell. [Figure 9] FIG. 2 is a schematic diagram of an alternative embodiment of an electrochemical cell. [Figure 10] 2 is a schematic diagram of an electrochemical cell with a return element according to a second embodiment, the return element being in a first configuration; [Figure 11] 2 is a schematic diagram of an electrochemical cell with a return element according to a second embodiment, the return element being in a second configuration; [Figure 12] 1 is a schematic diagram of the steps of a method for manufacturing an electrochemical cell according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] 1 and 2 present an example of the manufacture of an electrochemical cell 1 according to an embodiment of the present invention for an electric energy storage device. The energy storage device, also called "battery" or "electric battery", comprises a plurality of electrochemical cells 1 and, as a non-limiting example, may be intended for an automobile, in particular a vehicle with hybrid or electric drive. It should be noted that in all figures the dimensions and spacings separating the different components may be exaggerated for clarity.

[0022] The electrochemical cell 1 is capable of storing energy in chemical form and recovering energy in the form of electric current. The electrochemical cell may for example be of the "lithium-ion" type, also called "li-ion". In general, the electrochemical cell 1 comprises a rigid packaging 2, a number of electrodes 3 and a compression device 4 for the number of electrodes 3.

[0023] The rigid packaging 2 comprises in particular a housing 21 capable of receiving at least a plurality of electrodes 3 and defining a negative terminal of the electrochemical cell 1. The packaging 2 further comprises a cover 22 configured to cooperate with the housing 21, which, once coupled to the housing 21, defines a sealed space in which the plurality of electrodes 3 extend. The electrochemical cell 1 can thus have a cylindrical structure, in particular with a circular base, or a prismatic structure, in particular with a polygonal base, in particular with a square or rectangular shape. The packaging 2 (in particular the housing 21 and / or the cover 22) can be manufactured, for example, from nickel-plated aluminum or from a polymer material. It is therefore to be understood that a "rigid" packaging 2 is one that is hardly deformed or that does not deform at all, in particular due to the material or materials used for the manufacture of the packaging.

[0024] The electrodes 3 are arranged to show alternating anodes and cathodes, with at least one anode and one cathode separated by an electrically insulating separating element, not shown. The electrodes 3 can be arranged according to a winding, as shown in Figs. 1 to 12, or alternatively according to a stack. According to another alternative, not shown, the electrodes 3 can be arranged according to a combination of windings and stacks. In particular, when the electrodes 3 are arranged according to a winding, the winding is centered on an extension axis 200, whereas when the electrodes 3 are arranged according to a stack or a combination of stacks and windings, the winding can extend along such an extension axis 200. This configuration by stacking can be seen in particular in the case of a prismatic electrochemical cell, not shown.

[0025] Optionally, the electrochemical cell 1 can be at least partially filled with an electrolyte (e.g., an organic electrolyte) to immerse the plurality of electrodes 3. The electrolyte can consist of lithium salts (LiPF6, LiBF4, LiClO4, LiTFSI, LiFSI, LiBOB) dissolved in one or more organic solvents, such as carbonates of dimethyl, ethylene, diethyl, propylene, or acetonitrile, by way of non-limiting examples.

[0026] The compression device 4 according to the invention comprises a shell 5 and at least one return element 6 .

[0027] The shell 5 is manufactured from a metallic material, for example stainless steel. The shell 5 can comprise one or more parts 50, in particular one or more plates or platelets, arranged relative to one another and configured to inscribe the shell shape 5 and cooperate with one another. The shell 5 can for example be manufactured from initially flat or substantially flat parts, which can then be shaped or arranged, in particular around an axis, to adopt the shape of the shell 5.

[0028] The shell 5 is configured to surround the electrodes 3 along the contour of the winding or stack of the electrodes 3. In other words, in a plane perpendicular to the extension axis 200, the shell is configured to surround the electrodes 3 along around the base of the winding or stack of the electrodes. The shell 5 is configured to have a shape that complements or substantially complements the winding or stack of the electrodes 3, in order to maximize the direct or indirect contact surface with the electrodes 3. For example, when the electrodes 3 are arranged according to a winding, the shell 5 preferably has a circular base. Conversely, when the electrodes 3 are arranged according to a stack, the shell 5 has a polygonal base, in particular a square or a rectangle. In particular, the shell 5 is centered on a main axis 500, which may in particular coincide with the extension axis 200 of the electrodes 3.

[0029] The shell 5 is dimensioned and shaped in particular to have a closed shape along at least the contour or periphery of the electrodes 3 when placed in the electrochemical cell 1. The shell 5 has at least one overlapping area 51 of the individual parts, the overlapping area 51 being specific to one or more parts 50 of the shell 5. By "overlap" it is understood that the overlapping of the parts of the shell 5 along the radial axis 250 perpendicular to the extension axis 200 and / or the main axis 500. As shown in Figures 2, 5, 6 and 8, in the case of a shell 5 comprising a single part 50, the first end 511 and the second end 512 are opposite each other in the parts 50 forming the shell 5 and extend overlapping each other in the shell 5 when the shell 5 is placed in the electrochemical cell 1.

[0030] In particular, the shell 5 has a mobile structure. It is configured in such a way that the portions 511, 512 of the same overlapping area 51 are displaced relative to each other based on the volumetric changes of the electrodes 3 observed during operation, or even due to the aging of the electrochemical cell 1. Thus, during each charge and discharge of the electrochemical cell 1, the main dimension 550 of the base of the shell 5 is changed in order to accommodate the expansion or contraction of the volume of the electrodes. It should be understood that the "main dimension" is in particular the diameter of the circular base in the case of a cylindrical cell, or the diagonal of the polygonal base in the case of a prismatic cell. Thus, this kind of main dimension 550 increases with the expansion of the volume of the electrodes and, conversely, decreases with their contraction.

[0031] The result is that at least one overlapping area 51 has a surface that is variable according to the volume of the electrodes 3. When the volume of the electrodes 3 is at a minimum, for example when the electrochemical cell 1 is in a discharging phase and / or at the beginning of the service life, the surface of the overlapping area 51 is at a maximum. Then, the main dimension 550 of the shell 5 is also at a minimum. When the volume of the electrodes 3 increases, for example during charging of the electrochemical cell 1 and / or due to its aging, the first part 511 and the second part 512 are displaced relative to each other due to the forces exerted by the electrodes 3 on the shell 5. Then, the surface of the overlapping area 51 decreases. In particular, the value of the minimum surface can be previously predefined based on the maximum volume of the electrodes allowed by the cell, and as will be further explained below, this kind of volume can be conditioned, for example, by the dimensions of the packaging 2 and / or the return element 6.

[0032] Preferably, the overlap region 51 can be configured to be inscribed in an angular segment μ derived from the main axis 500 of between 10 and 30°, even between 10 and 20°, in particular when the surface of the overlap region 51 considered is smallest. The purpose of this type of configuration is in particular to prevent anomalous displacements of the parts 511, 512 of the shell 5, as well as to prevent the appearance of areas of the contours of the electrodes that are "bare", i.e. not surrounded by the shell 5 along the circumference considered.

[0033] Thus, the shell 5 is advantageously configured to allow gas evolution and absorption of the electrochemical cell 1, and its shape conforms to the volume changes of the electrodes 3 both during its usage cycle and over its lifespan. The behavior of the shell 5 in response to volume changes, particularly volume contraction, of the electrodes 3 is detailed further below.

[0034] Optionally, but preferably, the electrochemical cell 1 may additionally comprise an electrical insulating leaf 7 arranged around the electrodes 3 so as to be located between the electrodes 3 and the shell 5 along the radial axis 250. In particular, such a leaf 7 may be made of Mylar® polyester, for example. Such a leaf 7 may be an element added and arranged to extend around the winding or stack of electrodes 3, thereby preventing direct contact between the shell 5 and the electrodes 3 and their rubbing or short-circuiting. Alternatively, such a leaf 7 may correspond to the end of an insulating element incorporated in the winding or stack of electrodes 3 to separate the cathode from the adjacent anode. The insulating element is then dimensioned so as to be able to surround the stack or winding of electrodes 3.

[0035] According to an alternative embodiment, as can be seen in figures 10 and 11, the shell 5 can comprise several parts 50, in particular plates or platelets. These parts 50, movable relative to one another, are arranged to cooperate together and to inscribe in the shape that defines the shell 5. For example, as shown, said parts 50 correspond to cylindrical parts that are arranged to inscribe in the cylindrical or substantially cylindrical shape of the shell 5. A similar principle can also be implemented for prismatic structures.

[0036] As mentioned above, the shell 5 extends along the contour or periphery of the electrodes 3 and surrounds them. The shell 5 then has a number of overlapping regions 51, the number of which is in particular equal to the number of parts 50 of the shell 5. According to the illustrated non-limiting example, a first plate 52 and a second plate 53 facing each other in the plate under consideration each comprise a first end 511 and a second end 512. The first end 511 of the first plate 52 and the second end 512 of the second plate 53 are arranged to form a first overlapping region 51', and the first end 511 of the second plate 53 and the second end 512 of the first plate 52 are arranged to form a second overlapping region 51".

[0037] Preferably, as mentioned above, the first overlap region 51' and the second overlap region 51" can be configured to be inscribed in an angular segment derived from the main axis 500 of between 10 and 30°, in particular between 10 and 20°, in particular when the surface of the overlap region considered is smallest.

[0038] Also preferably, in order to optimize the contact surface between the parts 50 of the shell 5 and the electrodes, the different parts of the shell 5 are arranged such that the parts 511, 512 of the same part 50 alternate their position from one overlapping region 51 to another. For example, in the illustrated example, the first part 511 of the first plate 52 is placed along the radial axis 250 between the electrodes 3 and the second part 512 of the second plate 53 in the first overlapping region 51', while the second part 512 of the first plate 52 is at least separated from the electrodes 3 by the first part 511 of the second plate 53 in the second overlapping region 51".

[0039] Further, the shell 5 can be configured so that the first overlap region 51 and the second overlap region 51 have opposing or substantially opposing positions, e.g., in the illustrated example, have opposing positions along a diameter in the shell 5.

[0040] In the electrochemical cell 1, the shell 5 is placed along the radial axis 250 between the electrodes 3 and the at least one return element 6. In other words, the at least one return element is placed along the radial axis 250 between the electrodes 3 and the shell 5 on the one hand and at least a part of the packaging 2, in particular the housing 21, on the other hand. Figures 3 to 7 and 9 to 11 describe different embodiments and alternatives of the compression device 4. Figures 3 to 7 show an example of a compression device 4 with a single return element 6 manufactured according to a first embodiment. Figures 10 and 11 show an example of the manufacture of a second embodiment of the return element 6. Figure 9 describes an alternative manufacture of the compression device 4 with multiple return elements according to the first embodiment. It should be understood that when the compression device 4 comprises multiple return elements, all the descriptions given with respect to the return element 6 can be extended to all or part of the multiple return elements. The compression device 4 may also advantageously comprise a plurality of return elements 6 according to the second embodiment or, alternatively, a plurality of return elements 6 according to the first and / or second embodiment.

[0041] Generally, the return element 6 is at least partially elastically deformable and configured to deform between at least one first configuration and one second configuration according to the volume of the plurality of electrodes 3. It should be understood that such configurations represent the extreme positions of the return element 6, and at least one intermediate position can exist between said configurations. In particular, the first configuration can be considered as a so-called "rest" configuration in which the return element 6 returns or aims to return due to the elastic properties of the return element 6 when it is not subjected to a force or when such force is reduced.

[0042] According to a first embodiment, the return element 6 shown in FIGS. 3 to 7 comprises a body 61 and a number of fins 62 .

[0043] The body 61 has a closed structure and is configured to at least enclose the assembly formed by the plurality of electrodes 3 and the shell 5. In particular, the body 61 preferably has a shape that complements the shape of the shell 5 and / or the plurality of electrodes 3. The same applies to the body 61 of the return element 6, for example when the shell 5 has a circular base, thereby optimizing the contact surface between the return element 6 and the shell 5. A similar principle applies to shells 5 having a polygonal base, in particular a square or rectangular shape. As such, the body 61 can be centered on an axis 600 that can advantageously coincide with the extension axis 200 of the plurality of electrodes 3 and / or the extension axis 500 of the shell 5. In other words, the plurality of electrodes 3 and / or the shell 5 and / or the at least one return element 6 can be concentric or substantially concentric.

[0044] The body 61 has, in particular, a rigid structure, i.e. in particular a structure such that the body 61 is not or hardly deformed by the volumetric changes of the plurality of electrodes 3. The body may therefore be responsible for setting a limit to the maximum allowed volume of the plurality of electrodes 3.

[0045] The fins 62 are connected to the body 61 and have an elastically deformable structure. In particular, the body 61 and the fins 62 form a one-piece assembly, i.e. the body 61 and the fins 62 cannot be separated from each other without resulting in destruction or deterioration of the return element 6. For example, the return element 6 can be manufactured from stainless steel, and the fins 62 are then obtained by making cuts in the body 61, each fin 62 abutting an opening 64 contained in the body 61.

[0046] Below, a description is given of the fin 62, but it should be understood that any feature relating to the fin can be extended to all or part of the plurality of fins 62. The fin 62 has an elongated structure, for example a rectangular structure. In particular, the fin 62 can extend parallel or substantially parallel to the axis 600 of the body 61, in particular along the body 61.

[0047] The fin 62 can extend over all or part of the height 675 of the body 61, measured along the axis 600. According to a non-limiting example, the fin 62 can extend over at least most of the height 675 of the body 61, for example 70 to 95% of such height. Alternatively, a plurality of fins 62 can extend consecutively to one another along the height 675 of the body 61, each of said fins 62 then extending over a portion of the height 675 of the body 61. In particular, the body 61 can comprise two end lips 65 opposed along the axis 600 and solid, i.e. devoid of fins 62. The return element 6 can also extend over all or part of the height of the shell 5, such height being defined along the main axis 500 about which the shell 5 is centered. In other words, the height 675 of the return element 6 can advantageously be equal to or less than the height of the shell 5, the shell 5 distributing the forces exerted by the return element 6. Thus, by reducing the dimensions of the return element 6, the weight of the electrochemical cell assembly can be reduced.

[0048] The fin 62 is connected at one of its sides to the body 61 and has a slope α that is variable relative to the body 61, thus making the fin elastically deformable. The purpose of this kind of variability of the slope α is to ensure a permanent contact of the fin 62 with the shell 5, independent of the volume of the electrodes 3 and of the main dimension 550 of the base of the shell 5. As a result, the return element 6 exerts a constant and appropriate compression on the electrodes 3 so as to maintain a proper contact within the winding or stack, and this action is performed independently of the cycles of operation or wear of the electrochemical cell 1.

[0049] In particular, as shown in FIG. 5, the value of the inclination α is maximum when at least one return element 6 is in the first configuration, i.e. when the volume of the electrodes and the main dimension 550 of the shell 5 are minimum. The fins 62 are then deployed and extend to protrude from the body 61 in order to exert a compressive force on the shell 5 and thus indirectly on the electrodes 3. When the return element is displaced in the first configuration, i.e. when the fins are deployed and the inclination α increases, the force exerted by the return element 6 leads to a deformation of the body 5 and in particular to a displacement of the parts 511, 512 of the shell 5 relative to each other. The surface of the overlap area increases and the main dimension 550 of the shell 5 decreases. The return element 6 thus allows to press the shell 5 against the electrodes 3 when the volume of the electrodes 3 decreases, for example during a discharge phase, allowing a compression of the various components of the winding or stack, which maintain their good contact due to this compression. Then, when the return element 6 is in the first configuration, the gap separating the shell 5 from the body 61 of the return element 6 increases until it is at a maximum. As a preferred example, the fins 62 can be configured to have a maximum inclination α that is strictly less than 90°, in particular less than 85°.

[0050] Conversely, as mentioned above, when the volume of the electrodes 3 increases, the electrodes 3 exert a force on the shell 5, which transmits the force to the fins 62. Then, when the return element 6 is in the first configuration, the fins 62 are folded back towards the body 61, and the inclination α of the fins 62 decreases with respect to the observed one. The fins 62 thus folded back, when returning, exert a compressive force on the shell 5 and the electrodes 3, and also, as mentioned above, allow to maintain contact with the various components. In particular, when the at least one return element 6 is in the second configuration, i.e. when the volume of the electrodes is at a maximum with respect to the maximum limits allowed by the compression device 4 and / or the packaging 2 of the cell, the value of the inclination α is minimum. In particular, when the volume of the electrodes is at a maximum, the minimum inclination α can be zero, so that the shell 5 extends in contact with all or part of the fins 62 and the body 61.

[0051] The presence of the shell 5, in combination with the return element 6 and placed between the return element 6 and the plurality of electrodes 3 along the radial axis 250, therefore advantageously makes it possible to ensure a uniform distribution of the compressive force exerted by the return element 6 on the plurality of electrodes 3. The force exerted locally by the fin 62 on the outer surface 501 of the shell 5 is actually distributed in the structure of the shell 5, since the contact surface between the inner surface 502 facing the outer surface 501 of the shell 5 and the windings or stacks of electrodes 3 is greater than the contact surface observed between the fin 62 and the shell 5, thus allowing a more uniform transmission of the force exerted by the return element 6 on the plurality of electrodes 3.

[0052] For this purpose, the plurality of fins 62 of the return element 6 preferably have a regular configuration on the circumference of the body 61. In other words, the fins are periodically distributed on the body 61 and have spacings separating adjacent fins 62 that are regular. Likewise, the fins 62 of the plurality of fins 62 preferably have identical dimensions.

[0053] It should also be noted that the number of illustrated fins 62 distributed around the circumference of the body 61 is in no way limiting. It should be understood that the return element may comprise a different number of fins, more or less than the number depicted in the particular drawings.

[0054] As mentioned above, the compression device 4 may alternatively and advantageously comprise a plurality of return elements 6, each extending at least partially in contact with the shell 5. The above description applies mutatis mutandis to this alternative, and the features relating to the return element 6 are extendable to all or part of the plurality of return elements 6. In the example shown in Figure 9, the different return elements 6 are manufactured according to the first embodiment as described above, i.e. each comprises a body 61 and a plurality of fins 62.

[0055] The return elements 6 are arranged along at least one dimension, in particular the longest dimension, of the electrodes 3 and / or the shell 5. In other words, the return elements 6 can be arranged along the extension axis 200 of the electrodes 3 and / or along the main axis 500 about which the shell 5 is centered. For example, such a dimension can be the height of the shell 5 and / or, in the case of a cylindrical electrochemical cell 1 as shown, the height of the windings of the electrodes 3. The return elements 6 can then extend over all or part of such a dimension, and the different return elements 601, 602, 603 can or can not touch each other.

[0056] In this particular case, the compression device 4 comprises a first return element 601, a second return element 602 and a third return element 603 arranged along the main axis 500 of the shell 5 and along the extension axis 200 of the windings of the plurality of electrodes 3, i.e. along their height, in contact with each other. In particular, the first return element 601 and / or the second return element 602 and / or the third return element 603 can be coaxial. In particular, the first return element 601, the second return element 602 and the third return element 603 can be centered on the main axis 500 and / or the extension axis 200, i.e. all or part of the plurality of return elements 6 and / or the windings or stacks of the shell 5 and / or the electrodes 3 can be concentric.

[0057] The first return element 601 has a central location along the dimension under consideration, while the second return element 602 and the third return element 603 have more end locations along this same dimension. In other words, the second return element 602 and the third return element 603 extend on either side of the first return element 601 along the major axis 500 and / or the extension axis 200.

[0058] In particular, the different return elements can be configured to have different properties, for example different stiffness coefficients. Indeed, the variation in the volume of the electrodes 3 can be non-uniform within the considered winding or stack. In particular, it is known that this type of variation can be greater in the center of the winding or stack. Given this, the compression device 4 can be advantageously configured such that the first return element 601, having a central position along the height of the electrodes 3 and / or the shell 5, is characterized by a stiffness coefficient that is greater than the second return element 602 and / or the third return element 603.

[0059] This type of configuration therefore makes it possible, on the one hand, to facilitate the assembly of the electrochemical cell 1, as will be explained in detail below, and, on the other hand, to adapt the compression forces exerted on the shell 5 to any unevenness of the volume changes of the electrodes 3 observed in different parts of the winding or stack. It is to be understood that the example shown and described above in detail is in no way limiting. Also, when the compression device 4 comprises a plurality of return elements 6, the compression device 4 can comprise more or less than three return elements 6, the above description applying mutatis mutandis to this type of alternative example. Also, these different return elements 6 can then be arranged in contact with each other or with a non-zero distance from each other, so as to extend over all or part of the height of the shell 5, which advantageously allows the shell 5 to distribute the forces exerted by these different return elements.

[0060] According to other alternatives not shown which are possible according to the different embodiments and alternatives described above, the electrochemical cell 1 can, as an alternative or in combination with the above-mentioned embodiments and alternatives, comprise a plurality of shells 5 arranged along at least one dimension, in particular the longest dimension, of the plurality of electrodes 3. In other words, the plurality of shells 5 can be arranged along the extension axis 200 of the plurality of electrodes 3. The explanation given with respect to the plurality of return elements 6 applies here mutatis mutandis, with the plurality of shells 5 preferably extending over all considered dimensions of the plurality of electrodes.

[0061] Figures 10 and 11 show diagrammatically an example of the manufacture of an electrochemical cell 1 comprising a second embodiment of a return element 6, when the return element 6 is in a first configuration and a second configuration, respectively. The electrochemical cell 1 shown is distinct from the one described above in terms of its return element 6, so that the above explanations, in particular with regard to the structure of the electrochemical cell 1, the number of return elements 6 or the shells 5, apply mutatis mutandis to the following explanations.

[0062] In this embodiment, the return element 6 or alternatively at least one of the return elements 6 comprises a so-called "accordion" structure. In particular, this type of accordion structure is preferably inscribed in a shape that is complementary to the shape of the shell 5 and / or the electrodes 3. It is to be understood that an "accordion" structure is a structure that comprises a number of folds or, as shown, a number of folds 63 that are elastically deformable and that are defined by an angle β having a dimension that is variable according to the volume of the electrodes 3 and thus the main dimension 550 of the shell 5. The folds or folds 63 are defined here in a plane perpendicular to the extension axis 200 or the main axis 500, but it is nevertheless to be understood that the folds or folds 63 can extend over all or part of the height of the return element 6. In other words, the different folds or folds 63 can extend along the extension axis 200 of the electrodes 3 and / or the main axis of the shell 5. It is also to be understood that the shape of the folds or folds 63 shown is in no way limiting. Thus, such creases or folds 63 may have sharp, rounded and / or flat end parts or apexes as shown, as well as straight or curved portions as shown.

[0063] As mentioned above, the return element 6 according to this embodiment can be made of a metallic material, in particular stainless steel.

[0064] The angle β and / or shape of the folds 63 or wrinkles vary according to whether the at least one return element 6 is in a first configuration, i.e., where the volume of the plurality of electrodes 3 and the main dimension 550 of the shell 5 are at a minimum, or in a second configuration, i.e., where the volume of the plurality of electrodes 3 and the main dimension 550 of the shell 5 are at a maximum. As shown in FIG. 10, by way of example, when the return element 6 is at rest in the first configuration, the angle value β characteristic of each fold or wrinkle 63 can be between 40 and 120°, even between 45 and 60°.

[0065] The accordion structure therefore alternates between areas in which the return element 6 surrounds the shell 5 and contacts the shell 5 and areas in which it does not contact the shell 5, i.e. extends a non-zero distance from the shell 5. Each fold or crease 63 of the return element 6 is now bounded by two areas of contact with the shell 5 along the outer contour or periphery of the shell 5. Similarly, the return element 6 is directed towards the plurality of electrodes 3 and extends in contact with the packaging 2, in particular the inner surface of the packaging.

[0066] For example, as shown in the inset of FIG. 11, the compression device 4 according to the second embodiment allows a change in the volume of the winding or stack of electrodes 3 by implementing a greater or lesser squashing of the folds or creases 63 of the return element 6 between the shell 5 and the packaging 2 (the folds or creases 63 are deformed). The return element 6 thus allows a change in the volume of the plurality of electrodes 3 while supporting the packaging 2 and being in constant contact, at least partially in contact with the shell 5, and exerting a force on the shell 5 in the contact area, which is then uniformly transmitted to the plurality of electrodes 3. When the volume of the plurality of electrodes 3 increases, the main dimension 5 of the shell 5 also increases, squashing the return element 6 against the packaging 2. In the illustrated example, the straight part of the fold 63 is deformed to form a circular arc, and then the angle β is reduced in stages until the return element 6 reaches the second configuration. Then, when the return element 6 returns, it exerts a compressive force on the shell 5 and the plurality of electrodes 3 as described above. Conversely, when the volume of the plurality of electrodes 3 decreases, the return element 6 supported on the packaging 2 naturally returns to the first configuration. The return element 6 exerts a force on the shell 5, leading to a decrease in its main dimension 550, pressing the shell 5 against the plurality of electrodes 3. The compressive force thus exerted locally by the return element 6 on the shell is then, with respect to the first embodiment, transmitted more uniformly to the plurality of electrodes. It should be understood that the example of the crushing of the return element 6 is in no way limiting and is expressed here as an indication.

[0067] The present invention also relates to a method of manufacturing an electrochemical cell 1, as described above. In particular, the method shown in Figure 12 implements a compression device 4 with a single return element 6 according to the first embodiment. It is nevertheless understood that the method extends mutatis mutandis to the second embodiment and to the manufacturing alternative with multiple return elements 6 and / or shells 5.

[0068] The method may optionally include a step of stacking or winding a plurality of electrodes 3 to have alternating anodes and cathodes, in particular such that adjacent anodes and cathodes are separated by insulating elements as described above. Alternatively, a plurality of electrodes 3 can be pre-supplied and assembled according to a winding or stack.

[0069] The method according to the invention comprises a step E1 of positioning at least one return element 6 on a tool 8, in particular on a tool for holding and / or guiding at least one return element 6. When the compression device 4 comprises a plurality of return elements 6, the plurality of return elements 6 are arranged on the same tool 8. The tool can have, as a non-limiting example, a shape that at least partially complements the return element 6, in particular the inner surface of the return element 6. For example, for a return element 6 inscribed in a cylindrical or substantially cylindrical shape, the tool can have a cylindrical shape. In particular, such a tool can be configured to cooperate with the return element 6 when the return element 6 is in the first configuration and / or for positioning the return element 6 in the first configuration.

[0070] In parallel, the shell 5 is positioned around the winding or stack of multiple electrodes 3. This kind of positioning step can be performed before, simultaneously or after the step E1 of positioning at least one return element 6 on the tool.

[0071] When the electrochemical cell 1 comprises an electrically insulating leaf 7, the method according to the invention comprises a step of winding the electrodes 3 within the leaf 7 before positioning the shell 5 on the electrodes 3. In other words, the shell 5 is then placed around the assembly formed by the windings or stack of the leaf 7 and the electrodes 3, in direct contact only with the leaf.

[0072] The assembly formed by the plurality of electrodes 3 and the shell 5 is then placed E2 towards at least one return element 6 held by the tool. In particular, this kind of assembly is placed such that the shell 5 and the at least one return element 6 are concentric. In this particular case, both the shell 5 and the return element 6 are centered on the main axis 500 of the shell 5 and / or on the extension axis 200 of the windings of the electrode 3.

[0073] Next, in a deformation step E3, the at least one return element 6 is deformed so that it is arranged to surround the shell 5. In step E3, the at least one return element is deformed and displaced E3 relative to the shell 5, surrounding the shell 5 and the plurality of electrodes 3. In particular, the at least one return element 6 is displaceable by translational movement along a main axis 500 of the shell 5 and / or along an extension axis 200 of the windings or stacks of electrodes 3.

[0074] The assembly formed by the electrodes, the shell 5 and the at least one return element 6 can then be inserted into a rigid packaging 2, in particular into a housing 21. A cover 22 is then placed to hermetically close the cell and is then sealed. Alternatively, when the electrochemical cell 1 comprises an electrolyte, the electrolyte is inserted into the housing 21 before or after closing of the packaging 2 by injection such that the compression device 4 and the electrodes 3 are immersed in said electrolyte. The cover 22 can then be positioned and the packaging 2 is closed and sealed.

[0075] The invention therefore proposes an electrochemical cell for an electric energy storage device, in particular intended for motor vehicles, comprising a number of electrodes and a compression device adapted to the volumetric changes of the electrodes observed during cycles of operation and aging of the electrochemical cell. The compression device in particular comprises a shell and at least one return element that is at least partially elastically deformable. This type of compression device advantageously allows the compression adapted to the electrodes to be exerted constantly, by this action keeping its various elements in contact with one another, thus allowing a better uniformity of its operation and therefore of its aging, thus making it more suitable for new recharging modes.

[0076] However, the invention should not be limited to the means and configurations described and illustrated herein, but extends to any equivalent means or configurations, and to any technically operable combination of such means. In particular, the shape and dimensions of the electrical terminals or electrodes may be modified without impairing the invention, to the extent that they ultimately perform the functions described and illustrated in this document.

Claims

1. An electrochemical cell (1) for storing electrical energy, said electrochemical cell (1) comprising: a plurality of electrodes (3); a compression device (4) for said plurality of electrodes (3); and a rigid packaging (2) capable of receiving said plurality of electrodes (3) and said compression device (4), wherein said compression device (4) - at least one return element (6) which is at least partially elastically deformable and is configured to deform between a first configuration and a second configuration based on the volume of said plurality of electrodes (3), said at least one return element (6) being placed between said plurality of electrodes and at least a part of said rigid packaging (2); - a metal shell (5) comprising one or more parts (50), said shell (5) having at least one overlap region (51) of two separate parts of said shell (5) such that the surface varies according to the volume of said plurality of electrodes (3), said shell (5) being placed between said at least one return element (6) and said plurality of electrodes (3), said shell (5) surrounding said plurality of electrodes (3); An electrochemical cell (1) characterized by comprising the above.

2. Said at least one return element (6) comprises a rigid body (61) and a plurality of elastically deformable fins (62) connected to said body (61) and having an inclination (α) with respect to said body (61). When said at least one return element (6) is in said first configuration and a plurality of said fins (62) extend protruding from said body (61), the value of said inclination (α) is maximum. When said at least one return element (6) is in said second configuration and at least a plurality of said fins (62) extend and contact said shell (5), the value of said inclination (α) is minimum. The electrochemical cell (1) according to Claim 1.

3. Said at least one return element (6) has an "accordion" structure with a plurality of wrinkles or elastically deformable folds (63) whose shape and / or angle (β) vary according to the volume of said plurality of electrodes (3). The electrochemical cell (1) according to Claim 1.

4. The shell (5) is centered on the main axis (500), and the minimum surface of the overlap region (51) is delimited by an angular segment defined between 10 and 30°, particularly between 10 and 20°, in a plane derived from and perpendicular to the main axis (500). The electrochemical cell (1) according to any one of claims 1 to 3.

5. The plurality of electrodes (3) are arranged according to a winding centered on the extension axis (200) and / or according to a stack extending along the extension axis (200), and the at least one return element (6) and / or the shell (5) are centered on an axis of this kind. The electrochemical cell (1) according to any one of claims 1 to 3.

6. The compression device (4) comprises a plurality of return elements (6) arranged along at least one dimension, particularly the longest dimension, of the plurality of electrodes (3) and / or the shell (5), and the plurality of return elements (6) extend over all or part of this dimension. The electrochemical cell (1) according to any one of claims 1 to 3.

7. The plurality of return elements (6) comprise a first return element (601) having a central position along the defined dimension and at least one second return element (602, 603) having a more end position along this same dimension, and the first return element (6) has a higher rigidity coefficient than the at least one second return element (602, 603). The electrochemical cell (1) according to claim 6.

8. The electrochemical cell (1) further comprises an electrical insulation leaf (7) arranged around the plurality of electrodes (3) so as to be placed between the plurality of electrodes (3) and the shell (5). The electrochemical cell (1) according to any one of claims 1 to 3.

9. An electrical energy storage device, particularly for a motor vehicle, comprising at least one electrochemical cell (1) according to any one of claims 1 to 3.

10. A hybrid or electric vehicle comprising at least one electrochemical cell (1) according to any one of claims 1 to 3.

11. A method for manufacturing the electrochemical cell (1) according to any one of claims 1 to 3, the method comprising - a step (E1) of positioning the at least one return element (6) on a tool (8), particularly in the first configuration. - positioning the shell (5) around the plurality of electrodes (3); - arranging the assembly formed by the plurality of electrodes (3) and the shell (5) towards the at least one return element (6), in particular such that the shell (5) and the at least one return element (6) are concentric (step E2); then - deforming the at least one return element (6), in particular while the return element (6) is displaced relative to the shell (5) by a translational movement, such that the at least one return element (6) surrounds the shell (5) and the plurality of electrodes (3) (step E3); then - inserting the assembly formed by the plurality of electrodes (3), the shell (5) and the at least one return element (6) into the rigid packaging (2); A method comprising the above steps.

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