Block of battery cells, in particular for a motor vehicle

Abstract

This block (10) of battery cells comprises, juxtaposed with one another, a plurality of flexible accumulators (1) each comprising two tabs each placed in the plane and on an opposite side of said accumulator and forming its electrical poles. Said block (10) further comprises: - a plurality of pairs of stacked fastening elements (13) each comprising a first fastening element (14) bearing a first tab (15) of an accumulator, and a second fastening element (16) bearing a second tab (17) of said accumulator, said pair of fastening elements being intended to keep in contact with pressure said tabs against an adjacent pair of fastening elements and to form electrical connections with said tabs, - layers (11) comprising an electrically insulating material placed between each pair of adjacent accumulators, and - removable fastening means allowing the fastening elements (13) to be removably fastened.

Description

[0001] DESCRIPTION

[0002] TITLE: Battery cell block, in particular for a motor vehicle

[0003] Technical field

[0004] The present invention relates to the field of electrochemical accumulators and in particular metal-ion accumulators.

[0005] More specifically, the invention relates to a stack of flexible packaging accumulators, commonly called “pouch cells” in English or simply “cells” in the remainder of this application.

[0006] Previous techniques

[0007] As illustrated in Figure 1, an electrical energy accumulator 1 usually comprises at least one electrochemical cell 2 comprising an electrolyte 3 interposed between a positive electrode or cathode 4 and a negative electrode or anode 5, a current collector 6 connected to the cathode 4, a current collector 7 connected to the anode 5 and finally, a packaging 8 arranged to contain the electrochemical cell and make it sealed to the outside air and to the electrolyte inside the cell, while being crossed by a part of the current collectors.

[0008] Depending on the type of application, packaging can be flexible or rigid.

[0009] The main advantage of flexible packaging is its lightness. Batteries with the highest energy densities therefore have flexible packaging.

[0010] Figure 2 illustrates this type of flexible packaging 8 which is arranged to insulate and seal the electrochemical cell 2 while being crossed by a portion of two conductive tabs 6, 7. The conductive tabs, commonly called "tabs" in English, are each arranged on an opposite side of the accumulator 1 and extend in the plane of the electrochemical cell 2, of which they form the electrical poles. In most applications according to the prior art, it is necessary to associate several cells in series and / or in parallel to reach the targeted current and / or voltage level.

[0011] The battery or battery pack refers to the electrical energy storage element in its final form, but it is possible to identify several levels of cell grouping.

[0012] A module is a subset of identical cells, allowing higher-level granularity for systems requiring a large number of elementary cells. A module is a complex and expensive component, integrating multiple structural, electrical, thermal, etc. functions.

[0013] A battery is the result of associations of modules themselves made up of associations of cells.

[0014] For example, document CN 109428024-B describes a battery module in which flexible accumulators are assembled and connected to each other by means of fixing elements which clamp tabs folded and electrically connected by welding of a flat-shaped conductive element T.

[0015] These “module” type architectures use soldered electrical connections which cannot be dismantled in the event of failure.

[0016] Statement of the invention

[0017] The proposed invention aims to facilitate the replacement of flexible accumulators compatible with a so-called "cell to pack" architecture in English, in which the cells are integrated directly into the battery pack without there being any intermediate grouping of the "module" type as in document CN 109428024-B. In the remainder of this application, the expression "block of cells" or simply the term "block" therefore designates a plurality of cells arranged adjacently, which should not be confused with a "module", of which they do not reproduce all the functions.

[0018] The invention therefore relates to a battery cell block, in particular for a motor vehicle, comprising a plurality of flexible accumulators juxtaposed with each other and each comprising two tabs arranged on opposite sides of said accumulator and forming the electrical poles of the accumulator.

[0019] Said block also comprises a plurality of pairs of stacked fastening elements each comprising a first fastening element supporting a first tab of an accumulator, and a second fastening element supporting a second tab of said accumulator, said pair of fastening elements being intended to maintain in pressure contact said tabs against an adjacent pair of fastening elements and to constitute electrical connections with said tabs.

[0020] Said block also comprises layers comprising an electrically insulating material intended to reduce the vibrations of the accumulators and arranged between each pair of adjacent accumulators.

[0021] Said block further comprises removable fixing means allowing the fixing elements to be assembled in a removable manner.

[0022] According to one characteristic, said electrical connections are made by means of metal tabs arranged on said fixing elements and brought into contact with pressure with said tabs by stacking two fixing elements.

[0023] According to another characteristic, said layers comprise a foam or an adhesive.

[0024] Advantageously, each fixing element is provided with at least one boss arranged on an upper face of said fixing element and a cavity formed in alignment with said boss on a lower face of said fixing element, said cavity having a shape complementary to said boss and being intended to house the boss of an adjacent fixing element when it is stacked.

[0025] For example, the removable fastening means include clipping means and / or screwing means.

[0026] Advantageously, the fixing elements are provided with means for measuring tension and / or temperature. Preferably, the fixing elements are provided with means for pressurizing the metal tabs and the tongues.

[0027] According to another characteristic, said block is provided with electrical connection means which pass through the fixing elements inside sheaths arranged in said fixing elements.

[0028] The invention also relates to an electric battery comprising a plurality of blocks as described previously, said blocks being associated in series and / or in parallel.

[0029] The invention also relates to a motor vehicle equipped with a battery as described above.

[0030] Brief description of the drawings

[0031] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

[0032] [Fig 1] is a schematic perspective and exploded view showing the different elements of a lithium-ion accumulator;

[0033] [Fig 2] is a perspective view of a prismatic format lithium-ion accumulator with its flexible packaging according to the state of the art;

[0034] [Fig 3] a front sectional view of a battery pack according to the invention;

[0035] [Fig 4] and [Fig 5] are left and right views respectively of the battery pack shown in [Fig 3];

[0036] [Fig 6] is a front view of a fixing element according to the invention;

[0037] [Fig 7] a front view of a fixing element provided with pressure-applying means according to the invention; and

[0038] [Fig 8] illustrates electrical connection means according to the invention. Detailed description of at least one embodiment

[0039] Although described with reference to a lithium-ion accumulator, the invention applies to any metal-ion accumulator or more generally to any electrochemical accumulator.

[0040] A battery pack according to the invention may be on-board or stationary. For example, the fields of electric and hybrid transportation and grid-connected storage systems may be considered within the scope of the invention.

[0041] Figures 1 and 2, already commented on in the preamble, relate to examples of lithium-ion accumulators and flexible packaging according to the state of the art.

[0042] For the sake of clarity, the same references designating the same elements according to the state of the art and according to the invention are used for all the figures of the application.

[0043] In the examples illustrated, the accumulators 1 are in prismatic format with flexible packaging 8, usually called “pouch”.

[0044] We will now describe an embodiment of a battery pack according to the invention and illustrated in Figures 3 to 5.

[0045] Figure 3 is a front sectional view of a battery pack 10 according to the invention. Figure 4 and Figure 5 are respectively left and right views of the battery pack 10 illustrated in Figure 3.

[0046] The battery pack 10 comprises several juxtaposed electrical energy accumulators 1 separated from each other by layers 11 which are intended to reduce the vibrations of said accumulators 1. Each accumulator 1 comprises at least one electrochemical cell comprising an electrolyte interposed between a cathode and an anode, a current collector connected to the cathode, a current collector connected to the anode and a packaging.

[0047] The 1 1 layers are intended to provide support in the direction perpendicular to the plane of the cells to improve the mechanical support of the accumulators and promote good distribution of compression forces between the accumulators. In addition, the 1 1 layers include an electrically insulating material in order to reduce leakage currents that may be generated by the potential difference of the accumulators.

[0048] For example, layers 1 1 may include a foam or an adhesive.

[0049] Preferably, such a layer 11 is also arranged between an accumulator 1 and a support surface 12 on which the block 10 is fixed.

[0050] The block 10 comprises a plurality of stacked pairs of fixing elements 13 arranged on either side of the accumulators 1.

[0051] Although illustrated with reference to a vertical juxtaposition of the accumulators 1, the invention also covers the case where the accumulators are juxtaposed in a horizontal direction. In this case, the bearing surface 12 is vertical and the stacking of the fixing elements 13 is horizontal.

[0052] Each pair of fixing elements comprises a first 14 and a second 16 fixing elements each respectively supporting a first 15 and a second 17 tabs of an accumulator.

[0053] The pairs of fixing elements are intended to urge said tabs 15, 17 against an adjacent pair of fixing elements. It is therefore necessary to have three pairs of fixing elements to fix two cells and to add one pair of fixing elements to fix each additional cell.

[0054] The pairs of fixing elements are also intended to constitute electrical connections with said tabs.

[0055] Said electrical connections are made by means of metal tabs 18 arranged on said fixing elements 13 and brought into contact with pressure with said tabs 15, 17 by stacking two fixing elements 13.

[0056] The accumulators can be electrically connected in series and / or in parallel in a block 10 according to the invention.

[0057] The electrical series and / or parallel assembly depends on the orientation of the accumulators and the arrangement of the metal legs 18. It is understood that the arrangement of the metal legs 18 may be different from that illustrated in figures 3 to 5, depending on the intended assembly.

[0058] The battery pack 10 is provided with electrical connection means 21 which pass through the fixing elements inside sheaths 22 arranged in said fixing elements. The electrical connection means 21 serve to raise one of the electrical poles through the stack from an end close to the bearing surface

[0059] 12 towards the opposite end (figure 8). The electrical connection means 21 are distinct from the metal tabs 18.

[0060] The fixing elements 13 are provided with removable fixing means allowing the elements 13 to be assembled together in a removable manner.

[0061] The removable fixing means comprise clipping means and / or screwing means 19, 20.

[0062] In the embodiment illustrated in Figures 3 to 5, the assembly of the elements 13 is carried out by tightening screws 19, 20 which pass through the stack of fixing elements 13 and which are anchored in the bearing surface 12. Preferably, there is a pair of screws for each stack of fixing elements 13.

[0063] The boss 23 is connected to the cavity 25 by a threaded cylindrical channel 27 intended to collaborate with the screws 19, 20 (figure 6).

[0064] Figure 6 is a front view of a fastening element 13. The fastening element 13 comprises at least one boss 23 arranged on an upper face 24 of said fastening element. The fastening element

[0065] 13 comprises a cavity 25 formed in alignment with said boss 23 on a lower face 26 of said fixing element. The cavity 25 has a shape complementary to the boss 23 and is intended to house the boss 23 of an adjacent fixing element 13 during its stacking. The presence of the bosses 23 and the associated cavities 25 tend to facilitate the relative positioning of the fixing elements 13.

[0066] In another embodiment not illustrated, the assembly of the fixing elements 13 is carried out by clipping means arranged on the bosses 23 and the cavities 25. For example, the bosses 23 are provided with an elastic snap-on hook facing outwards which snaps into a snap-on opening provided on an outer edge of the cavities 25 when the elements 13 are stacked. For disassembly, the snap-on hooks are pushed inwards from the snap-on opening.

[0067] It is of course still possible to combine the screwing means and the clipping means for assembling the fixing elements 13.

[0068] Figure 7 is a front view of a fixing element 13 provided with a first 28 and second 29 cavities each arranged respectively on the upper 24 and lower 26 faces of said fixing element.

[0069] The cavities 28, 29 house means 30 for applying pressure to the metal tabs 18 with the tongues 15, 17. The pressure means 30 comprise springs which tend to push the ends of the metal tab 18 outwards and aim to increase the contact pressure with the tongues 15, 17. It is possible, depending on the desired configuration, to provide pressure means 30 only in one of the cavities 28, 29.

[0070] The fixing elements 13 are further provided with means 31 for measuring voltage and / or temperature. The measuring means 31 comprise an electrical connection 32 which connects the metal tab 18 and a measuring terminal 33 arranged on a lateral face of said fixing element 13.

[0071] The pressure-applying means 30 can be used to increase the contact pressure between the electrical connection means 21 and the tabs 15, 17 (figure 8).

[0072] In order to reduce electrical risks, the block 10 may further comprise covers made of electrically insulating material arranged on the metal legs of the fixing elements, in order to prevent any accidental contact of said metal legs with the exterior.

[0073] Depending on the intended configuration, several battery blocks 10 can be associated in series and / or in parallel within an electric battery. The invention aims to improve the mass energy density of such a battery, because the accumulators 1 are arranged directly inside the battery without using a mechanical protection structure of the “module” type for the battery blocks 10.

Claims

CLAIMS 1. Battery cell block (10), in particular for a motor vehicle, comprising: - a plurality of flexible accumulators (1), juxtaposed to one another and each comprising two tabs (6, 7) arranged on opposite sides of said accumulator and forming the electrical poles of the accumulator, characterized in that said block (10) further comprises: - a plurality of pairs of stacked fixing elements (13) each comprising a first fixing element (14) supporting a first tab (15) of an accumulator, and a second fixing element (16) supporting a second tab (17) of said accumulator, said pair of fixing elements being intended to maintain said tabs in pressure contact against an adjacent pair of fixing elements and to constitute electrical connections with said tabs, layers (11) comprising an electrically insulating material intended to reduce the vibrations of the accumulators and arranged between each pair of adjacent accumulators, and removable fixing means making it possible to assemble the fixing elements (13) in a detachable manner.

2. Block according to claim 1, in which said electrical connections are made by means of metal tabs (18) arranged on said fixing elements (13) and brought into contact with pressure with said tabs (15, 17) by stacking two fixing elements (13).

3. Block according to any one of claims 1 or 2, wherein said layers (11) comprise a foam or an adhesive.

4. Block according to any one of the preceding claims, in which each fixing element (13) is provided with at least one boss (23) arranged on an upper face (24) of said fixing element and a cavity (25) formed in alignment with said boss on a lower face (26) of said fixing element, said cavity having a shape complementary to said boss and being intended to house the boss (23) of an adjacent fixing element when it is stacked.

5. Block according to any one of the preceding claims, in which the removable fixing means comprise clipping means and / or screwing means (19, 20).

6. Block according to any one of the preceding claims, in which the fixing elements (13) are provided with means (31) for measuring tension and / or temperature.

7. Block according to any one of the preceding claims, in which the fixing elements are provided with means for pressurizing (30) the metal tabs (18) and the tongues (15, 17).

8. Block according to any one of the preceding claims, provided with electrical connection means (21) which pass through the fixing elements (13) inside sheaths (22) arranged in said fixing elements.

9. Electric battery comprising a plurality of blocks (10) according to any one of the preceding claims, said blocks being associated in series and / or in parallel.

10. Motor vehicle equipped with a battery according to claim 9.

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