Device for storage of electrical energy and electrical connection means capable of securing a constituent cell of such a storage device

Abstract

The present invention relates to a device for storage of electrical energy comprising at least a cell and a housing, the housing comprising at least one holder receiving the cell, the at least one cell comprising a first electrical connection terminal arranged on the upper face of the cell and in contact with the upper wall of the housing, said cell comprising a second electrical connection terminal formed at least by the peripheral face, the device for storage of electrical energy comprising an electrical connection means in contact with the second electrical connection terminal, the electrical connection means forming a retention member for retaining the cell within the housing.

Description

[0001] Electrical energy storage device and electrical connection means suitable for securing a cell constituting such a storage device

[0002] The present invention relates to the field of electrical energy storage devices such as battery packs for electric or hybrid vehicles.

[0003] Electrical energy storage devices comprise a plurality of cells arranged side-by-side within a casing. These cells can be electrically connected in series or parallel to increase, respectively, the voltage or the capacity of the electrical energy storage device. The cells include a first electrical connection terminal and a second electrical connection terminal. The casing houses at least one electrical circuit capable of connecting the first connection terminals of several cells, as well as a second electrical circuit capable of connecting the second connection terminals of these cells.

[0004] Such a storage system requires the individual cells to be fixed within the casing so that they do not move during vehicle operation. This fixing is necessary to prevent damage to the storage system by generating potential short circuits or breaks in contact between the cells and the electrical circuits to which they are connected. These short circuits or breaks in contact can cause malfunctions in the electrical energy storage system.

[0005] It is then known to permanently bond the cells within the casing of the electrical energy storage device. This bonding secures the cells within the casing, making them very difficult to separate from the casing should any maintenance or repairs be required. For example, the cells are glued inside the casing of the electrical energy storage device. Furthermore, these cells must be thermally regulated. The currently known solution is a coil running inside the casing, alongside the cells, through which a fluid circulates to manage the temperature.

[0006] These energy storage devices are used in systems subject to increasingly stringent standards, such as those in the automotive industry. The growth of these standards necessitates finding solutions to improve the repairability of such electrical storage devices. Furthermore, these standards are pushing industry players to anticipate the issue of recycling these electrical energy storage devices.

[0007] These new constraints may not be taken into account in the electrical energy storage system described above, since gluing the cells makes them very difficult to dismantle for potential repair or recycling at the end of their lifespan. Furthermore, the arrangement of the coil that manages the cells' thermal performance also complicates the repair of such an electrical energy storage system.

[0008] The present invention falls within this context and aims to propose an electrical energy storage device in which the cells are made attached to the casing via a device which allows for a simpler dismantling of the cells than the solution described above, such a device participating in the electrical connection function of the cell as well as in the thermal management function.

[0009] The present invention proposes an electrical energy storage device comprising at least one cell and a housing, said cell being disposed in a volume delimited by the housing, the cell being delimited by a lower face and an upper face between which extends a peripheral face, the housing comprising at least a lower wall and an upper wall, at least one of these walls comprising a support receiving the cell, the lower face and the upper face of the cell being respectively opposite the lower wall and the upper wall of the housing, the at least one cell comprising a first electrical connection terminal disposed on the upper face of the cell and in contact with the upper wall of the housing, said cell comprising a second electrical connection terminal formed at least by the peripheral face,The electrical energy storage device includes an electrical connection means in contact with the second electrical connection terminal, the electrical connection means forming a cell retention element within the housing.

[0010] The electrical energy storage device according to the invention may, for example, be a battery pack suitable for equipping an electric or electrified motor vehicle, whose purpose is, in particular, to store or supply electrical energy to the electric or electrified motor vehicle during its use or during the charging of the electrical energy storage device. This electrical energy storage device is characterized by the presence of at least one electrical connection means whose primary function is to ensure electrical contact between the electrical circuit and a cell. The connection means has a second function, which is to hold the cell in position while allowing it to be removed from the casing.

[0011] The electrical connection method is particularly advantageous here, and especially simple to use, as it includes a retaining device capable of holding the cell in position within the housing. Thus, when the cell is positioned in the housing, the retaining device applies a force to the cell, locking it in place. This force nevertheless allows for separation without damaging the cell from the housing.

[0012] According to an optional feature of the invention, the electrical connection means forming the retaining member is configured to allow the cell to be removed from the housing.

[0013] The retaining mechanism has a shape and flexibility that allows the cell to be detached from the casing without damaging either the cell or the casing. This technical feature makes it possible, on the one hand, to repair the storage device if at least one cell fails, and on the other hand, to recycle the electrical energy storage device more easily because separating the cells from the casing becomes simpler.

[0014] The retaining device is configured to allow one cell to be removed and another to be locked in place when the latter is inserted into the housing.

[0015] According to an optional feature of the invention, the retaining element comprises at least one leaf spring bearing against the cell. For example, the leaf spring is the retaining element itself.

[0016] The leaf spring applies a force to the outer surface of the cartridge, holding the cartridge in position. The leaf spring has a stiffness chosen to exert the necessary force to hold the cartridge against the housing. Such a leaf spring bends when it comes into contact with the cartridge.

[0017] According to an optional feature of the invention, the cell forms a cylinder. In the context of repairability and recyclability, the cylindrical shape of the cell is particularly well suited.

[0018] The cylinder formed by the cell is preferably round in cross-section.

[0019] According to an optional feature of the invention, the support consists of three pads configured to center the cell. A portion of the cell is housed between these three pads, which are distinct from one another.

[0020] The case includes a plurality of supports, each capable of receiving a cell.

[0021] Each support comprises three pads configured to allow the positioning and centering of a cell. Each pad has a face in the shape of an arc of a circle with a radius substantially similar to that of the cell's peripheral wall. The three pads each cover substantially identical angular sectors, and they are spaced approximately 120° apart.

[0022] According to an optional feature of the invention, the electrical connection means protrudes from at least one pad of the support towards the cell. The electrical connection means passes through the pad and protrudes from this pad towards a volume intended to be occupied by the cell. The portion of the electrical connection means protruding from the pad forms the cell retention element.

[0023] The retaining element allows electrical contact between the electrical connection means and the peripheral face of the cell. As previously mentioned, the retaining element is a spring-loaded element which, in addition to conducting current to and from the cell, locks it in position between the three contacts.

[0024] According to an optional feature of the invention, the retaining device comprises at least two spring blades arranged angularly to each other at an angle between 120 and 180°.

[0025] The spring blades of the electrical connection means are arranged at 120° intervals around a cell. The 120° angle is measured from the center of the cell when it is installed in the support.

[0026] A retaining element comprises three leaf springs, each positioned on a face forming an arc of a pad. These three leaves protrude from the pad they pass through and ensure the centering of the cell, with at least one of the leaf springs providing the electrical connection to the first or second electrical circuit. According to an optional feature of the invention, a single pad contributes to the centering of at least two cells, advantageously three cells.

[0027] Within the housing, each pad is in contact with three cells, except for the pads located on an outer ring surrounding the internal volume of the housing where the cells are arranged; these pads are in contact with only two cells. In one variant, a pad comprises at least two arc-shaped faces, advantageously three arc-shaped faces, with a dedicated spring blade protruding from each arc-shaped face.

[0028] According to an optional feature of the invention, the electrical energy storage device includes a cooling circuit, at least a portion of the electrical connection means being heat-treated by the cooling circuit. The cooling circuit is a circuit that channels a heat transfer fluid, optionally a dielectric. The cooling circuit includes a passage extending under the plurality of cells, such a passage being located within the lower wall of the casing. This circuit also includes at least one heat exchanger capable of exchanging heat with an environment external to the cooling circuit, so as to dissipate or absorb heat, depending on the need to heat or cool the electrical energy storage device.

[0029] A portion of the electrical connection means exchanges with the cooling circuit.

[0030] In a cooling application example, the electrical connection means may have a temperature higher than that of the fluid circulating in the cooling circuit. The fluid is configured to reduce the temperature of the electrical connection means. Since all the current captured or delivered by the cell passes through the connection means, it is advantageous to cool it to increase its capacity to carry electrical current at high voltage or current, particularly in the case of rapid charging of the electrical energy storage device according to the invention.

[0031] The portion of the electrical connection means exchanging with the cooling circuit can, for example, extend into the cooling circuit so as to exchange directly with the fluid included in the cooling circuit.

[0032] According to a variant of this embodiment, the portion of the electrical connection means is not located within the cooling circuit. Heat exchange can then be achieved by conduction through the case wall.

[0033] According to an optional feature of the invention, the electrical energy storage device includes a dielectric fluid that circulates within the cooling circuit.

[0034] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples of embodiments given with reference to the attached schematic drawings on the other hand, in which:

[0035] [fig 1] is a cross-sectional view of the storage device showing the internal volume of a casing in which extends at least one cell, a support and the cooling circuit constituting the electrical energy storage device;

[0036] [fig 2] is a cross-sectional view of a second embodiment of the electrical connection means;

[0037] [fig 3] is a top view of the storage device showing a cell in its receiving area surrounded by pads and means of electrical connection;

[0038] [fig 4] is a cross-sectional view of a second embodiment of the plots;

[0039] [fig 5] is a cross-sectional view of a third embodiment of the studs.

[0040] Figure 1 is a schematic representation of the electrical energy storage device 2. The electrical energy storage device 2 can, for example, be a battery pack suitable for use in an electric or hybrid vehicle to power that vehicle. The electrical energy storage device 2 comprises a casing 4 defined by an upper wall 6 and a lower wall 8, for example, parallel to each other. Between this upper wall 6 and this lower wall 8, the casing 4 delimits an internal volume within which electrical storage cells 10, hereinafter referred to as cells, are arranged.

[0041] Figure 1 is a cross-sectional view of the electrical energy storage device 2, showing the internal volume of the casing 4. The casing 4 is also closed by side walls not shown in the figures so as to create the internal volume separate and isolated from an external environment of the electrical energy storage device 2.

[0042] The electrical energy storage device 2 comprises cells 10 that can be considered as electrical energy accumulators. Figure 1 shows only one cell 10 for simplicity, but a plurality of these cells 10 are arranged within the internal volume of the casing 4. The cell 10 has a cylindrical shape extending between an upper face 12 and a lower face 14, with a peripheral face 16 extending between the upper face 12 and the lower face 14. The lower face 14 of the cell 10 faces the lower wall 8 of the casing 4, and the upper face 12 of the cell 10 faces the upper wall 6 of the casing 4. The cell 10 is oriented along an elongated direction that is perpendicular to the lower wall 8 of the casing 4.

[0043] The cell 10 includes a first electrical connection terminal 18 arranged on its upper face 12, the first electrical connection terminal 18 being opposite the upper wall 6 of the housing 4. The upper wall 6 of the housing 4 includes a connector 20 configured to be in contact with the first electrical connection terminal 18 when the cell 10 is arranged in the internal volume of the housing, between the upper wall 6 and the lower wall 8 of the housing 4.

[0044] The upper wall 6 of the housing 4 includes a plurality of interconnected connectors 20 so as to put in series or parallel the plurality of cells 10 and thus adapt the storage or release capacities of the electrical energy storage device 2.

[0045] The first electrical connection terminal 18 is electrically isolated from the peripheral face 16 of the cell 10, the peripheral face 16 of the cell 10 thus forming a second electrical connection terminal of the cell 10. The first electrical connection terminal 18 and the peripheral face 16 must therefore not be in contact. Electrical insulation between the first electrical connection terminal 18 and the peripheral face 16 is provided inside the cell 10. Alternatively, an insulator 22 is arranged around the first electrical connection terminal 18 so as to prevent any risk of electric arcing between the peripheral face 16 of the cell 10 and the first electrical connection terminal 18 of the cell 10.

[0046] The cell 10 is positioned in the housing 4 via a support 24, which allows the cell 10 to be placed in the housing 4. The support 24 protrudes from the lower wall 8 of the housing 4. The support 24 can, for example, be made by continuous material with the lower wall 8 when the lower wall 8 is molded. An alternative support 24, not shown in the figures, is one in which the lower wall 8 includes receiving holes configured to cooperate with extensions of the support 24, so as to secure the support 24 to the lower wall 8. The support 24 has a height less than a distance between the lower wall 8 and the upper wall 6 of the housing 4. This height is measured in a direction perpendicular to the lower wall 8 of the housing 4.

[0047] The support 24 is advantageously composed of a plurality of pads 26 arranged around the cell 10. The embodiment shown in figures 1 to 5 comprises three pads 26 arranged around the cell 10, each pad 26 being angularly arranged at the same angular value from one pad to the other, thus forming a triangular support for the cell 10. In addition, the pads 26 are arranged so as to keep the cells 10 placed in the housing 4 at a distance so that they cannot come into contact with each other.

[0048] Each pin 26 includes at least one electrical connection means 28 in contact with the peripheral face 16 of the cell 10. The contact of the electrical connection means 28 with the peripheral face 16 allows the electric current to flow to or from the cell 10. At least some of the cells 10 included in the housing 4 are interconnected, in a manner similar to the electrical connection mentioned above with respect to the first electrical connection terminals 18 of the cells 10.

[0049] The electrical connection means 28 extends at least partly into the pad 26, i.e. inside it, and includes a portion projecting from the pad 26 towards a receiving area of ​​the cell 10, the latter being defined as the volume surrounded by the pads 24 forming the support of a cell 10.

[0050] The portion projecting from the stud 26 can be considered a mechanical retainer for the cell within this receiving zone. The retainer can, for example, take the form of a spring leaf 30, the latter being made of an electrically conductive material and capable of flexing to exert a pressure force against the cell 10 when the latter is inserted into the receiving zone. In the case illustrated in Figures 1, 4, and 5, this spring leaf 30 is straight and flat. The cell 10 is positioned at the center of the studs 26. This cell 10 is held in position by the spring leaves 30 applying a force against the peripheral face 16 of the cell 10. The spring leaves 30 act as springs that press against the peripheral face 16 of the cell 10.The direction of the spring blades 30 is modified when the cell 10 is inserted into the support 10, because the cell 10 twists the spring blades 30 while remaining within the elastic limit of these spring blades 30.

[0051] The cross-sectional view in Figure 1 shows the lower wall 8 of the housing 4 in which a portion of the cooling circuit 32 extends. Such a portion is a pass of the cooling circuit where heat exchanges with the cells 10 take place.

[0052] The cooling circuit 32 is configured to allow the circulation of a dielectric fluid, for example. The cooling circuit 32 includes a heat exchanger that allows heat to be exchanged with an environment external to the electrical energy storage device 2. As the cooling circuit 32 is not fully represented, the heat exchanger is therefore not shown in the figures.

[0053] The electrical connection means 28 carries a significant electric current, which generates considerable heat. It is therefore necessary to provide a means of lowering the temperature of the electrical connection means 28 so that it remains within the operating temperature range specified by the manufacturer of the electrical connection means 28.

[0054] It is noted that another portion, referenced 34, of the electrical connection means 28 exchanges heat with the cooling circuit 32. The passage of the cooling circuit 32 being located in the thickness of the lower wall 8 of the housing 4, it is close to the electrical connection means 28. A heat exchange therefore takes place between the electrical connection means 28 and the fluid circulating in the cooling circuit 32.

[0055] According to one embodiment, portion 34 of the electrical connection means 28 exchanges directly with the dielectric fluid by extending within the pass of the cooling circuit 32. Portion 34 of the electrical connection means 28 is in direct contact with the dielectric fluid.

[0056] According to an alternative embodiment not shown in the figures, the portion 34 of the electrical connection means 28 is disposed in contact with the lower wall 8. In this way, the portion 34 of the electrical connection means 28 exchanges by conduction through the lower wall 8 with the dielectric fluid.

[0057] Figure 2 is a schematic representation of a second embodiment of the electrical connection means 28 in which the spring blades 30 have a different shape from that of the first embodiment.

[0058] In this second embodiment, the spring blades 30 of the electrical connection means 28 have a curved shape capable of flattening when the cell 10 is placed in the support 24. Such an embodiment makes it possible to avoid damaging the peripheral face 16 of the cell 10 when it is inserted or removed from the support 24 since in this embodiment the spring blade 30 does not have a sharp edge in contact with the peripheral face 16 of the cell 10.

[0059] The means of electrical connection may include other forms of spring blade not shown in the figures.

[0060] Figure 3 is a schematic representation of the electrical energy storage device 2 seen from above, without the upper wall 6 of the case 4. The case 4 is truncated so as to show a cell 10 in its entirety, as well as the support 24 which holds it.

[0061] Figure 3 illustrates the arrangement of the studs 26 of the support 24 around the peripheral face 16 of the cell 10. The studs 26 have a face in the shape of an arc of a circle having a radius complementary to the radius of the cell 10. The studs 26 allow the cell 10 to be centered in the housing 4.

[0062] Each pad 26 is in contact with three cells 10, and three pads 26 are required to center a single cell 10. In this way, the pads 26 comprise three circular arcs capable of cooperating with three immediately adjacent cells 10. Each circular arc face of a pad 26 includes an electrical connection means 28, the latter projecting from the center of the circular arc. Thus, three electrical connection means 28 are in contact with the peripheral face 16 of the same cell 10. In one example, only one of these three electrical connection means 28 supplies electrical current to the cell 10. In another example, all three electrical connection means 28 conduct electrical current to or from the cell 10, thereby reducing the heating of the electrical connection means 28.

[0063] The spring blades 30 are distributed angularly at 120° to each other around the cell 10. The angle between the spring blades 30 is measured around a center of the receiving area of ​​the cell 10.

[0064] Furthermore, the distance separating each of the spring blades 30 measured in a plane parallel to the lower wall 8 is substantially identical, so as to guarantee centering of the cell 10 in its support 24.

[0065] The use of multiple electrical connection means 28 bearing against the same cell 10 ensures, on the one hand, good electrical contact between the cell 10 and the rest of the electrical circuit and, on the other hand, distributes the current flow areas to reduce the thermal increase of the electrical connection means 28. Furthermore, this or these electrical connection means form a thermal drain that channels the heat generated by the cell 10 towards the cooling circuit 32. Figure 4 is a schematic representation of a second embodiment of the support 24. In this second embodiment of the support 24, the lower wall 8 and the upper wall 6 of the housing 4 each include at least one support 24. The supports 24 protrude from the lower wall 8 and the upper wall 6. The supports 24 can, for example, be formed by continuous material with said walls 6, 8.

[0066] Such a support arrangement 24 at each end of the cell 10 allows for better centering of the cell 10. The pads 26 on the upper wall 6 and the pads 26 on the lower wall 8, which center the cell 10, are opposite each other. The pads 26 have a height strictly less than half the distance measured between the upper wall 6 and the lower wall 8. This distance is measured in a direction perpendicular to the lower wall 8 of the housing 4. By having a height less than half the distance between the lower wall 8 and the upper wall 6, this limits potential interference between the pads 26 on the upper wall 6 and the pads 26 on the lower wall 8 during the assembly of the housing 4.

[0067] According to another embodiment not shown in the figures, the electrical connection means 28 is carried by the support 24 of the upper wall 6 of the housing 4. In this embodiment, the electrical connection means 28 retains the cell 10 in the support 24 of the upper wall 6 of the housing 4, even when it is suspended under the upper wall 6, before the housing 4 is closed by placing the lower wall 8.

[0068] The electrical connection means 28 therefore generates a support force via the spring blades 30 which blocks the positioning of the cell 10. As a result, the spring blades 30 apply a force which holds the cell 10 in place, such a force being greater than the force of gravity applied to the cell 10.

[0069] Figure 5 is a schematic representation of a third embodiment of the support 24 in which two supports 24 are included in the housing 4. In this third embodiment, at least one of the pads 26 of the upper wall 6 and at least one pad 26 of the lower wall 8 include an alignment member 36 provided on a face of the pad 26 concerned, opposite the lower wall 8, respectively of the upper wall 6.

[0070] For example, the alignment member 36 takes the form of a finger that fits into a cavity with a shape complementary to that of the finger, both being formed at the end of a stud 26. The finger and the cavity are configured to cooperate so that they fit together. The alignment member 36 thus makes it possible to connect two studs originating from different walls, so as to better protect the cell 10 along its entire height between the lower wall 8 and the upper wall 6 of the housing 4. Of course, the invention is not limited to the examples just described, and numerous modifications can be made to these examples without departing from the scope of the invention.

[0071] The invention, as described above, achieves its intended purpose and provides an electrical energy storage device that includes means for simplifying cell separation from the casing, thereby increasing the repairability and recyclability of the electrical energy storage device according to the invention. Variations not described here could be implemented without departing from the scope of the invention, provided that, in accordance with the invention, they include an electrical connection means forming a retaining element as described therein.

Claims

DEMANDS 1- Electrical energy storage device (2) comprising at least one cell (10) and a housing (4), said cell (10) being arranged in a volume delimited by the housing (4), the cell (10) being delimited by a lower face (14) and an upper face (12) between which extends a peripheral face (16), the housing (4) comprising at least one lower wall (8) and an upper wall (6), at least one of these walls (6, 8) comprising a support (24) receiving the cell (10), the lower face (14) and the upper face (12) of the cell (10) being respectively opposite the lower wall (8) and the upper wall (6) of the housing (4), the at least one cell (10) comprising a first electrical connection terminal (18) disposed on the upper face (12) of the cell (10) and in contact with the upper wall (6) of the housing (4),said cell (10) comprising a second electrical connection terminal formed at least by the peripheral face (16), the electrical energy storage device (2) comprising an electrical connection means (28) in contact with the second electrical connection terminal, the electrical connection means (28) forming a retaining element for the cell (10) within the housing (4). 2- Electrical energy storage device (2) according to the preceding claim, in which the electrical connection means (28) forming the retaining member is configured to allow removal of the cell (10) from the housing (2). 3- Electrical energy storage device according to any one of the preceding claims, wherein the retaining member comprises at least one leaf spring (30) bearing against the cell (10). 4- Electrical energy storage device (2) according to any one of the preceding claims, wherein the cell (10) forms a cylinder. 5- Electrical energy storage device (2) according to any one of the preceding claims, wherein the support (24) consists of three pads (26) configured to center the cell (10). 6- Electrical energy storage device (2) according to the preceding claim, in which the electrical connection means (28) protrudes from at least one stud (26) of the support (24) towards the cell (10). 7- Electrical energy storage device (2) according to the preceding claim, in which the retaining member comprises at least two spring blades (30) arranged angularly to each other at an angle between 120 and 180°. 8- Electrical energy storage device according to any one of claims 5 to 7, wherein a single pad (26) participates in the centering of at least two cells (10). 9- Electrical storage device (2) according to any one of the preceding claims, comprising a cooling circuit (32), at least a portion of the electrical connection means (34) being heat-treated by the cooling circuit (32). 10- Electrical energy storage device (2) according to the preceding claim, comprising a dielectric fluid which circulates within the cooling circuit (32).

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