A set of cells in an energy storage element and a method for assembling said set

Abstract

A set (10) of cells (11, 12) of an energy storage element comprising at least one first and one second adjacent cells (11, 12), each comprising two electrical connection tabs (13, 14), respectively of positive polarity and negative polarity. Each of the tabs (13) of the first cell (11) comprises a folded portion (13b) extending from said first cell (11) to the second cell (12), and each of the tabs (14) of the second cell (12) comprises a folded portion (14b) extending from said second cell (12) to the first cell (11).The assembly (10) comprises a successive stack including a support (15), a first conductive bar (16), the folded portion (13b) of the connecting tab (13) of the first cell (11), a second conductive bar (17), the folded portion (14b) of the connecting tab (14) of the second cell (12), and a third conductive bar (18), the assembly (10) comprising reversible fastening means (19, 22) for said stack configured to apply a clamping force to said stack. Figure for the abbreviation: [Fig 2].

Description

Title of the invention: Set of cells of an energy storage element and method of assembling said set Technical field of the invention

[0001] The present invention relates to the field of electrical energy accumulators such as batteries.

[0002] More particularly, the invention relates to the electrical connection of cells, in particular so-called “pouch” cells, within a battery to form a set of cells. State of the prior art

[0003] Electrical energy accumulators comprise electrochemical elements or so-called “pouch” cells.

[0004] With reference to [Fig.l], the set 1 of cells 1a to 1h, here eight in number. Each of the cells comprises two electrical connection tabs 2a, 3a to 2h, 3h, respectively of positive polarity and negative polarity.

[0005] In order to connect the cells together, it is known to use laser welding to connect the tabs of the cells. However, laser welding is not suitable for all metallic materials, particularly in the context of an association of a copper part with an aluminum part. In addition, such a fixing does not allow the cells of the same subassembly to be separated without damaging it.

[0006] Another solution for connecting the cells consists of assembling the cells by stamping or clinching by adding a U-shaped section part. However, such a solution considerably increases the size of the assembly and requires sufficient passage for a tool allowing the stamping of the part. Furthermore, such a fixing also does not allow the cells of the same subassembly to be separated without damaging it.

[0007] It is also known to use ultrasonic welding to connect the cells together. Although such a solution allows for mechanical strength, it requires sufficient passage for a tool allowing welding. Furthermore, such a fixing also does not allow the cells of the same subassembly to be separated without damaging it and can generate internal mechanical stresses on the cells.

[0008] There is a need to optimize the electrical connection of cells within a battery. Statement of the invention

[0009] The present invention therefore aims to overcome the aforementioned drawbacks.

[0010] The objective of the invention is to improve the electrical connection of the cells of a set of cells of a battery in order to allow the individual disassembly of the cells, while minimizing the impact on the total mass of the set of cells and ensuring the electrical performance of the cells.

[0011] The subject of the invention is a set of cells of an energy storage element, such as a battery, comprising at least one first and one second adjacent cell each comprising two electrical connection tabs, respectively of positive polarity and negative polarity.

[0012] Each of the tabs of the first cell comprises a folded portion extending from said first cell towards the second cell and each of the tabs of the second cell comprises a folded portion extending from said second cell towards the first cell.

[0013] The assembly comprises a successive stack comprising at least one support, a first conductive bar, the folded portion of one of the connection tabs of the first cell, a second conductive bar, the folded portion of one of the connection tabs of the second cell, and a third conductive bar.

[0014] The set of cells comprises reversible fixing means for said stack configured to apply a clamping force to said stack.

[0015] Thus, the electrical connection of the cells of a set of cells of a battery is efficient and it is possible to dismantle individual cells, for example during a maintenance operation, without affecting the mechanical integrity of the other cells.

[0016] For example, it could be provided that the set of cells comprises a number greater than or equal to three cells arranged in parallel or in series.

[0017] Advantageously, each electrical connection tab comprises a first part extending from one end of the main portion of the corresponding cell and a folded portion extending from one end of the first part perpendicular to said first part.

[0018] Thus, the folded portion extends along the longitudinal axis perpendicular to the extension axis of the cell towards the adjacent cell.

[0019] In other words, the folded portion of the electrical connection tab of the first cell extends along the longitudinal axis towards the adjacent second cell and the folded portion of the electrical connection tab of the second cell extends along the longitudinal axis towards the adjacent first cell.

[0020] The conductive tabs have, for example, a thickness of the order of 0.15 mm.

[0021] The conductive tabs are, for example, made of metallic material, such as copper, aluminum, nickel. Thus, the conductive tabs are capable of being bent.

[0022] Advantageously, the electrically insulating support is arranged between the two adjacent cells and the first conductive bar is arranged on the support.

[0023] The support comprises, for example, a width less than the longitudinal distance between two adjacent cells.

[0024] In other words, a longitudinal clearance remains between the support and each of the cells.

[0025] The first, second and third conductive bars are preferably made of the same material, such as for example a metallic material, such as aluminum.

[0026] Thus, the first, second and third conductive bars have the same electrical resistivity.

[0027] Advantageously, the second conductive bar has a thickness greater than the thickness of each of the first and third conductive bars.

[0028] Indeed, the current supplied by the first cell is carried by the first and second conductive bars and the current supplied by the second cell is carried by the second and third conductive bars. Thus, the second conductive bar carries a current coming from both the first cell and the second cell. For example, the thickness of the second conductive bar is equal to twice the thickness of each of the first and third conductive bars.

[0029] Thus, the temperature of the conductive bars in contact with the cells is homogenized, which makes it possible to homogenize the temperature of the cells.

[0030] Advantageously, each of the first, second and third bars comprises a bore cooperating with the reversible fixing means, said bores being coaxial to allow the passage of said fixing means.

[0031] For example, the reversible fixing means comprise at least one screw means cooperating with the support.

[0032] According to one embodiment, the screwing means is a screw cooperating with a thread made in the support.

[0033] Alternatively, it could be provided that the support comprises a threaded extension, for example a stud, extending into the holes in the conductive bars and cooperating with a nut.

[0034] The fixing of the successive stack of the support, the first conductive bar, the folded portion of the connection tab of the first cell, the second conductive bar, the folded portion of the connection tab of the second cell, and the third conductive bar is carried out by screwing the screws into the corresponding thread made in the support, or by tightening the nut cooperating with the stud.

[0035] The pressure applied when tightening the screws or nut allows the passage of the current required between the conductive bars and the tabs by deformation of said conductive bars on the tabs.

[0036] According to one embodiment, the reversible fixing means comprise at least two screw means each cooperating with the support.

[0037] According to one embodiment, the assembly further comprises a spring means, for example in the form of a spring blade, mounted between the two serial screw means and the third conductive bar.

[0038] Thus, the spring blade comprises a first portion fixed to a first screw means secured to the support portions of the conductive bars, a second portion fixed to a second screw means secured to the connecting portions of the conductive bars and a central portion connecting the first and second portions. The central portion rests on the third conductive bar.

[0039] According to one embodiment, the folded portions of the tabs of the cells each comprise a through hole cooperating with the screw means.

[0040] Said through hole is coaxial with the holes made on the first, second and third bars and with the tapping or the threaded stud of the support.

[0041] For example, the first, second, and third bars have a shape configured to connect one of the tabs of one cell with one of the tabs of an adjacent cell.

[0042] For example, the cell set comprises a number of cells equal to eight.

[0043] For example, the first, second and third bars have an E shape. comprising a plurality of transverse support portions, each bearing on the folded portion of the tongue of the second cell and a longitudinal connecting portion connecting said support portions.

[0044] Preferably, in the case of an even number of cells, the number of support portions is equal to half the number of cells. In the case of an odd number of cells, the number of support portions is equal to half the number of cells plus one support portion.

[0045] Each of the support portions of the third conductive bar may comprise a through-hole cooperating with a screw.

[0046] Similarly, each of the support portions of the first and second conductive bars may comprise a through bore, only two of which cooperate with the screw. The bores made on the first, second and third bars are coaxial.

[0047] For example, the connecting portion of the third bar further comprises a second series of holes opening into a thread made in the support.

[0048] According to a second aspect, the invention relates to a method of assembling a cell assembly of an energy accumulator, such as a battery, comprising at least at least one first and one second adjacent cell each comprising two electrical connection tabs, respectively of positive polarity and negative polarity.

[0049] According to the assembly method: - a first conductive bar is positioned on a support; - one of the tabs of the first cell is folded onto the first conductive bar until a folded portion of said tab rests on said first conductive bar; - a second conductive bar is positioned on the folded portion of said tab of the first cell; - one of the tabs of the second cell is folded onto the first conductive bar until a folded portion of said tab rests on said second conductive bar; - a third conductive bar is positioned on the folded portion of said tab of the second cell; and - the successive stack of the support, the first conductive bar, the folded portion of the connection tab of the first cell, the second conductive bar, the folded portion of the connection tab of the second cell, and the third conductive bar are fixed by reversible fixing means.

[0050] Said reversible fixing means are configured to apply a clamping force to said stack.

[0051] At the end of the stacking step, a successive stack of the support, the first conductive bar, the folded portion of the connection tab of the first cell, the second conductive bar, the folded portion of the connection tab of the second cell, and the third conductive bar is thus obtained. Brief description of the drawings

[0052] 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 indexed drawings in which:

[0053] [Fig.l], is a perspective view of a set of cells of a battery according to the state of the art;

[0054] [Fig.2] is a sectional view of a set of cells according to one embodiment of the invention;

[0055] [Fig.3] is a partial perspective view of a step in assembling the set of cells according to [Fig.2];

[0056] [Fig.4] is a perspective view of the cell set according to [Fig.2];

[0057] [Fig.5] is a sectional view of a set of cells according to another embodiment of the invention;

[0058] [Fig.6] is a sectional view of a set of cells according to another embodiment of the invention; and

[0059] [Fig.7] represents a flowchart of a process for assembling the cell assembly of [Fig.2],

[0060] Detailed description of at least one embodiment

[0061] In the remainder of the description, we define an orthonormal reference frame X, Y, Z in which:

[0062] - the X axis represents a longitudinal axis defining the stacking axis of the cells of the set of cells;

[0063] - the Y axis represents a transverse axis, extending across the width of the cells; and

[0064] - the Z axis represents a vertical axis, perpendicular to the longitudinal axis X and to the axis transverse Y.

[0065] With reference to the example illustrated in Figures 2 to 4, a set 10 of cells of a battery arranged in parallel along the longitudinal axis X.

[0066] As illustrated in [Fig.2], the assembly 10 comprises, in a non-limiting manner, two cells 11, 12. Alternatively, it could be provided that the assembly 10 comprises a number greater than or equal to three cells arranged in parallel.

[0067] Each cell 11, 12 comprises a main portion 11a, 12a extending along the vertical axis and two electrical connection tabs 13, 14, respectively of positive polarity and negative polarity, only one of which is visible in [Fig.2].

[0068] Each electrical connection tab 13, 14 comprises a first portion 13a, 14a extending from one end of the main portion 11a, 12a of the corresponding cell 11, 12 and a folded portion 13b, 14b extending from one end of the first portion 13a, 14a perpendicular to said first portion 13a, 14a. Thus, the folded portion 13b, 14b of each connection tab extends along the longitudinal axis X towards the adjacent cell 11, 12.

[0069] In other words, the folded portion 13b of each electrical connection tab 13 of the first cell 11 extends along the longitudinal axis X towards the adjacent second cell 12 and the folded portion 14b of each electrical connection tab 14 of the second cell 12 extends along the longitudinal axis X towards the first cell adjacent 11.

[0070] As illustrated in [Fig.2], the assembly 10 further comprises an electrically insulating support 15 arranged between two adjacent cells 11, 12. The longitudinal dimension or width along the longitudinal axis X of the support 15 is, here, less than the longitudinal distance between two adjacent cells 11, 12. In other words, a longitudinal clearance remains between the support 15 and each of the cells 11, 12.

[0071] As illustrated in [Fig.2], the assembly 10 further comprises a first conductive bar 16 arranged on the support 15 and on which the folded portion 13b of the connection tab 13 of the first cell 11 rests.

[0072] The assembly 10 further comprises a second conductive bar 17 arranged on the folded portion 13b of the connection tab 13 of the first cell 11 and on which the folded portion 14b of the connection tab 14 of the second cell 12 bears, and a third conductive bar 18 arranged on the folded portion 14b of the connection tab 14 of the second cell 12.

[0073] Thus, the assembly 10 comprises successively along the vertical axis Z, the support 15, the first conductive bar 16, the folded portion 13b of the connection tab 13 of the first cell 11, the second conductive bar 17, the folded portion 14b of the connection tab 14 of the second cell 12, and the third conductive bar 18.

[0074] The current supplied by the first cell 11 is carried by the first and second conductive bars 16, 17 and the current supplied by the second cell 12 is carried by the second and third conductive bars 17, 18.

[0075] The first, second and third conductive bars 16, 17, 18 are preferably made of the same material, such as for example a metallic material, such as aluminum. Thus, the first, second and third conductive bars 16, 17, 18 have the same electrical resistivity.

[0076] The second conductive bar 17 carries a current from both the first cell 11 and the second cell 12. The second conductive bar 17 preferably has a thickness greater than the thickness of each of the first and third conductive bars 16, 18. For example, the thickness of the second conductive bar 17 is equal to twice the thickness of each of the first and third conductive bars 16, 18.

[0077] Thus, the temperature of the conductive bars 16, 17, 18 in contact with the cells 11, 12 is homogenized, which makes it possible to homogenize the temperature of the cells 11, 12.

[0078] The first, second and third bars 16, 17, 18 have a shape configured to connect one of the tabs of a cell with one of the tabs of an adjacent cell.

[0079] As can be seen in Figures 3 and 4 which illustrate an example of a set 10 comprising a number of cells equal to eight.

[0080] As illustrated in [Fig.3] and in a non-limiting manner, the first, second and third bars 16, 17, 18 have an X shape, equivalent to the juxtaposition of an E shape with an inverted E shape.

[0081] The shape will be described with reference to the third bar 18, it being understood that the first and second bars 16, 17 have a shape identical to the shape of the third bar 18.

[0082] The third conductive bar 18 comprises four transverse support portions 18a, 18b, 18c, 18d, each bearing on the folded portion 14b of the tongue 14 of the second cell 12 and a longitudinal connecting portion 18a connecting said support portions 18a, 18b, 18c, 18d.

[0083] Alternatively, a different number of support portions could be provided. The number of support portions is equal to half the number of cells.

[0084] Each of the support portions 18a, 18b, 18c, 18d of the third conductive bar 18 comprises a through bore 20a, 20b, 20c, 20d cooperating with a screw 19, forming a reversible fixing means.

[0085] Similarly, each of the support portions of the first and second conductive bars 16, 17 comprises a through bore, of which only two bores 17a, 17b are visible in [Fig. 3], cooperating with the screw 19. The bores made on the first, second and third bars 16, 17, 18 are coaxial.

[0086] The connecting portion 18a of the third bar 18 further comprises a second series of holes 21 opening into a thread (not visible in the figures) made in the support 15.

[0087] Alternatively, it could be provided that the support 15 comprises a threaded extension, for example a stud, extending into the holes in the conductive bars 16, 17, 18 and cooperating with a nut.

[0088] The fixing of the successive stack of the support 15, of the first conductive bar 16, of the folded portion 13b of the connection tab 13 of the first cell 11, of the second conductive bar 17, of the folded portion 14b of the connection tab 14 of the second cell 12, and of the third conductive bar 18 is carried out by screwing the screws 19 into the corresponding tapping made in the support 15.

[0089] The pressure applied when tightening the screws 19 allows the passage of the necessary current between the conductive bars 16, 17, 18 and the tabs 13, 14 by deformation of said conductive bars 16, 17, 18 on the tabs 13, 14.

[0090] Thus, in the event of replacement of a cell of the set 10 of cells, it is sufficient to remove the third conductive bar 18 then the second conductive bar 17 in the case where it is a question of replacing the first cell 11. The folded portions 13b, 14b of the tabs 13, 14 of the cell to be replaced are unfolded.

[0091] The unitary disassembly of each cell makes it possible to reduce the maintenance cost.

[0092] The tabs have a low thickness, for example 0.15 mm, which generates an electrical stress. The folding and unfolding of the folded portions of the tabs is thus facilitated.

[0093] [Fig. 5] illustrates another embodiment, in which the same elements bear the same references and which differs from the embodiment illustrated in FIGS. 2 to 4 only by the fact that the assembly 10 comprises a spring means 22, in the form of a spring blade.

[0094] The spring blade 22 is mounted between two screw means 19 (screw or nut) and the third conductive bar 18.

[0095] Thus, the spring blade 22 comprises a first portion 22a fixed to a first screw means 19 secured to the support portions of the conductive bars 16, 17, 18, a second portion 22b fixed to a second screw means 19 secured to the connecting portions of the conductive bars 16, 17, 18 and a central portion 22c connecting the first and second portions 22a, 22b. The central portion 22c bears on the third conductive bar 18.

[0096] [Fig. 6] illustrates another embodiment, in which the same elements bear the same references and which differs from the embodiment illustrated in FIGS. 2 to 4 only by the fact that the folded portions 13b, 14b of the tabs 13, 14 of the cells 11, 12 of the assembly 10 each comprise a through hole (not visible) cooperating with the screw means 19. Said through hole is coaxial with the holes made on the first, second and third bars 16, 17, 18 and with the tapping or the threaded stud of the support 15.

[0097] [Fig.7] illustrates a method 30 for assembling the set 10 of cells of [Fig.2] in which, in step 31, the first conductive bar 16 is positioned on the support 15, then, in step 32, the tab 13 of the first cell 11 is folded onto the first conductive bar 16 until the folded portion 13b rests on said first conductive bar 16.

[0098] Then, in step 33, the second conductive bar 17 is positioned on the folded portion 13b of the tab 13 of the first cell 11 and, in step 34, the tab 14 of the second cell 12, adjacent to the first cell 11, is folded onto the first conductive bar 16 until the folded portion 14b is resting on said second conductive bar 17.

[0099] The third conductive bar 18 is then positioned, in step 35, on the folded portion 14b of the tab 14 of the second cell 12.

[0100] At the end of step 35, a successive stack of the support 15, of the first conductive bar 16, of the folded portion 13b of the connection tab 13 of the first cell 11, of the second conductive bar 17, of the folded portion 14b of the connection tab 14 of the second cell 12, and of the third conductive bar 18.

[0101] Next, in step 36, said stack is fixed by means of reversible fixing means, such as the screw means 19 configured to apply a clamping force to said stack.

[0102] The connection of the cells is described here with reference to a connection of the cells in parallel with the connection of the negative electrodes on the one hand and the positive electrodes on the other hand. Alternatively, such a connection could be provided to connect cells in series with the connection of the negative electrodes with the positive electrodes of an adjacent cell.

[0103] Thanks to the invention, it is easy to replace the cells of a cell assembly individually without damaging the rest of the assembly.

Claims

Claims

1. Set (10) of cells (11, 12) of an energy storage element comprising at least one first and one second adjacent cell (11, 12) each comprising two electrical connection tabs (13, 14), respectively of positive polarity and negative polarity, characterized in that each of the tabs (13) of the first cell comprises a folded portion (13b) extending from said first cell (11) towards the second cell (12) and each of the tabs (14) of the second cell comprises a folded portion (14b) extending from the second cell (12) towards the first cell (11), and in that the set (10) comprises a successive stack comprising a support (15), a first conductive bar (16), the folded portion (13b) of one of the connection tabs (13) of the first cell (11), a second conductive bar (17), the portion folded (14b) of one of the connecting tabs (14) of the second cell (12),and a third conductive bar (18), the assembly (10) comprising reversible fixing means (19, 22) for said stack configured to apply a clamping force to said stack.,

2. An assembly (10) according to claim 1, wherein the electrically insulating support (15) is arranged between the two adjacent cells (11, 12) and wherein the first conductive bar (16) is arranged on the support (15).

3. Assembly (10) according to claim 1, in which the support (15) comprises a width less than the longitudinal distance between two adjacent cells (11, 12).

4. An assembly (10) according to claim 1 or 2, wherein the first, second and third conductive bars (16, 17, 18) are made of the same material.

5. An assembly (10) according to any preceding claim, wherein the second conductive bar (17) has a thickness greater than the thickness of each of the first and third conductive bars (16, 18).

6. An assembly (10) according to any preceding claim, wherein each of the first, second and third bars (16, 17, 18) comprises a bore cooperating with the fixing means (19), said bores being coaxial.

7. An assembly (10) according to any preceding claim, in which the reversible fixing means comprise at least one screw means (19) cooperating with the support (15).

8. Assembly (10) according to claim 7, in which the reversible fixing means comprise at least two screw means (19) each cooperating with the support (15).

9. An assembly (10) according to claim 8, comprising a spring means (22) mounted between the two screw means (19) and the third conductive bar (18).

10. Assembly (10) according to any one of the preceding claims, in which the folded portions (13b, 14b) of the tabs (13, 14) of the cells (11, 12) each comprise a through hole cooperating with the screw means (19).

11. Method for assembling a set (10) of cells (11, 12) of an energy storage element comprising at least one first and one second adjacent cell (11, 12) each comprising two electrical connection tabs (13, 14), respectively of positive polarity and negative polarity, in which: - a first conductive bar (16) is positioned on a support (15); - one of the tabs (13) of the first cell (11) is folded onto the first conductive bar (16) until a folded portion (13b) of said tab (13) is supported on said first conductive bar (16); - a second conductive bar (17) is positioned on the folded portion (13b) of said tab (13) of the first cell (11); - one of the tabs (14) of the second cell (12) is folded onto the second conductive bar (17) until a folded portion (14b) of said tab (14) rests on said second conductive bar (17);- a third conductive bar (18) is positioned on the folded portion (14b) of said tab (14) of the second cell (12); and - the successive stack of the support (15), the first conductive bar (16), the folded portion (13b) of the connection tab (13) of the first cell (11), the second conductive bar (17), the folded portion (14b) of the connection tab (14) of the second cell (12), and the third conductive bar (18) is fixed by reversible fixing means (19, 22), said reversible fixing means being configured to apply a clamping force to said stack.;

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