Cell for electric battery and its manufacturing process

Abstract

An electric battery cell comprising at least one successive stack of a sheet: - a first positive electrode (2) comprising an upper edge (4), - a first insulating separator, - a second negative electrode (3) comprising a lower edge (5), - a second insulating separator, said at least one stack being wound on itself around a central axis (Y) so as to form a cylinder, said first electrode (2) and said second electrode (3) each comprising at least two series (6) of current collection tabs (7), each series (6) comprising at least two current collection tabs (7), having a given height (9), a cell in which in a given series (6) the current collection tabs (7) have a substantially identical height (9) and the height (9) of the current collection tabs (7) is different from one series (6) to another. Figure for abstract: Figure 1

Description

Title of the invention: Cell for electric battery and its manufacturing method Technical field of the invention

[0001] The invention relates to the field of electric batteries for electric motor vehicles. In particular, the invention relates to electric battery cells. More specifically, the invention relates to cylindrical type cells. Technical background

[0002] Cylindrical type electric battery cells are increasingly used in the automotive industry.

[0003] The advantage of cylindrical cells lies in their ability to store a significant amount of energy in a small volume. They therefore occupy less space in the motor vehicle for a given energy storage capacity.

[0004] The energy storage capacity of a cylindrical cell is a function of its diameter. Thus, the larger the diameter of a cylindrical cell, the greater its capacity to store energy.

[0005] The cylindrical cells are manufactured by winding around a mandrel, a successive stack of at least: - a positive electrode sheet, - an insulating separator sheet, - a negative electrode sheet, - an insulating separator sheet.

[0006] Along the electrode sheets, current collection tabs are attached and fixed to said positive and negative electrode sheets. These current collection tabs allow the electrons to be routed and thereby an electric current to be routed. Although automated, this operation slows down the production rate of so-called cylindrical cells. In addition, a defect in the attachment and / or contact between the tabs and the electrodes can reduce the performance of the cylindrical cells, or even cause short circuits.

[0007] In order to overcome these problems, manufacturers have proposed doing away with tabs added and then fixed to the electrodes.

[0008] One of these solutions consists of making cuts directly on the electrode sheets not coated with active material to form current collection tabs before winding around a rotating mandrel. Once winding is complete, these tabs are folded and brought into contact with an attached current collector.

[0009] A disadvantage of this method lies in the difficulty of folding the tabs due, among other things, to their large number. In addition, fixing the tabs in the folded position is tedious and encounters technical difficulties when it comes to achieving industrial rates.

[0010] The invention therefore aims to solve the aforementioned problems. Summary of the invention

[0011] To this end, there is proposed firstly an electric battery cell for an electrically powered vehicle, said cell comprising at least one successive stack of a sheet: - a first positive electrode comprising an upper edge, - a first insulating separator, - a second negative electrode comprising a lower edge, - a second insulating separator, said at least one stack being wound on itself around a central axis so as to form a cylinder, said first electrode and said second electrode each comprise at least two series of current collection tabs, each series comprising at least two current collection tabs, each of the current collection tabs extending from the upper edge in the first electrode and from the lower edge in the second electrode, to respectively an upper peak and a lower peak, over a given height measured along the central axis, cell in which in a given series the current collection tabs have a substantially identical height and the height of the current collection tabs is different from one series to another.

[0012] Such a cell having current collection tabs whose height varies from one series to another makes it easier to fold the current collection tabs.

[0013] Various additional features may be provided alone or in combination: - the height of the current collecting tabs decreases as one moves along the first electrode and the second electrode and towards a winding direction; - once the stack is wound on itself around the central axis, the cell comprises several rows of current collection tabs, said rows extending from a periphery of the cell towards a center of said cell located on the central axis; - the height of the current collection tabs decreases as one moves from the periphery towards the center; - a first separation distance between two current collection tabs of a given series is substantially identical, the first distance being measured along a first axis substantially perpendicular to the central axis and parallel to the upper and lower edges; - the first distance is different from one series to another; - the first distance is proportional to the height of the current collecting tabs in a given series; - the first distance decreases from one series to another depending on whether one moves along the first electrode and the second electrode towards a winding direction; - a second distance separating two neighboring series of current collection tabs and measured along a first axis substantially perpendicular to the central axis and parallel to the upper and lower edges, said second distance changing as one moves along the first electrode and the second electrode; - the second distance decreases as one moves along the first electrode and the second electrode, towards a winding direction; - the current collection tabs have an isosceles trapezoid shape; - the current collection tabs include: - a first upper base merged with the upper edge of the first electrode and a first lower base merged with the lower edge of the second electrode, - a second upper base merged with the upper top of the current collection tab and a second lower base merged with the lower top of the current collection tab, - two upper side edges connecting the first upper base to the second upper base and two lower side edges connecting the first lower base and the second lower base; - the first base has a first length and the second base has a second length less than the first length, the first length and the second length being measured along the first axis; - the first length and the second length have a ratio between 1 and 2; - the current collection tabs have a substantially rectangular shape; - the current collection tabs of a given series have a third given length, measured along the first axis; - from one series to another, the third length is different; - the third length decreases as one moves towards a winding direction; - each current collection tab comprises a cutout along the central axis, said cutout separating each current collection tab into two half-tabs of substantially identical dimensions; - in the first electrode, the cut extends from the upper edge to the upper apex and in the second electrode, the cut extends from the lower edge to the lower apex. Brief description of the figures

[0014] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0015] [Fig-1] [Fig.l] is a schematic representation of electrodes according to the invention,

[0016] [Fig.2] [Fig.2] is a schematic representation of electrodes according to a variant of realization,

[0017] [Fig.3] [Fig.3] is a schematic representation of electrodes according to a variant of realization,

[0018] [Fig.4] [Fig.4] is a schematic representation of electrodes according to a variant of realization,

[0019] [Fig.5] [Fig.5] is a representation of a cell according to the invention. Detailed description of the invention

[0020] In [Fig.5] is shown a cell 1 of a rechargeable electric battery, for electrically powered vehicle. Cell 1 comprises at least one successive stack of a sheet: - a first positive electrode 2, - a first insulating separator (not shown in the drawings), - a second negative electrode 3, - a second insulating separator (not shown in the drawings).

[0021] The first electrode 2 comprises an upper edge 4. The second electrode 3 comprises a lower edge 5.

[0022] In the remainder of the description, longitudinal, transverse and vertical orientations will be adopted in a non-limiting manner - and without reference to Earth's gravity - indicated by the trihedron X, Y, Z of the figures and in which: - the X axis corresponds to a first longitudinal axis parallel to the upper and lower edges, - the Y axis, perpendicular to the X axis, corresponds to a central axis of the cell around which it is wound, - the Z axis, perpendicular to the X axis and the Y axis, corresponds to a second transverse axis. The XYZ trihedron defines the XY, XZ and YZ planes.

[0023] As previously mentioned, the stack is wound on itself around the Y axis. The stack thus wound forms a cylinder.

[0024] The first electrode sheet 2 and the second electrode sheet 3 each comprise at least two series 6 of current collecting tabs 7. Each series 6 comprises at least two current collecting tabs 7. In the embodiment shown in the drawings, the first electrode sheet 2 comprises three series 6 and each series 6 comprises four current collecting tabs 7 without this being limiting.

[0025] In the first electrode sheet 2, each current collection tab 7 extends from the upper edge 4 to an upper vertex 8 over a given height. In the second electrode sheet 3, each current collection tab 7 extends from the lower edge 5 to a lower vertex 10 over a given height 9. The height 9 is measured along the Y axis.

[0026] In a given series 6 of current collection tabs 7, all the current collection tabs 7 have an identical height 9.

[0027] The height 9 of the current collection tabs 7 is, however, different from one series 6 to another. Indeed, in a first series 11, the current collection tabs 7 have a first height 16. In a second series 12, the current collection tabs 7 have a second height 17 greater than the first height 16. In a third series 13, the current collection tabs 7 have a third height 18 greater than the second height 17.

[0028] Once the stack is wound around the Y axis, the current collection tabs 7 are folded over each other. The current collection tabs 7 are folded from a periphery 14 of the cell 1 towards a center 15 of said cell 1.

[0029] Such a cell 1 having current collection tabs 7 whose height 9 varies from one series 6 to another makes it easier to fold the current collection tabs 7.

[0030] Advantageously, the height 9 of the current collection tabs 7 decreases as one moves along the first electrode 2 and the second electrode 3, towards a winding direction 19.

[0031] This makes it easier to fold the current collection tabs 7. In fact, the current collection tabs 7 of smaller height 9 are thus located close to the Y axis of the cell. At the time of folding, it becomes possible to avoid a mass of metal does not form near the Y axis, thus simplifying the assembly of cell 1.

[0032] Advantageously, and with reference to [Fig. 5], the cell 1 comprises several rows 20 of current collection tabs 7. The rows 20 extend from the periphery 14 of the cell 1 towards a center 15 of said cell 1, said center 15 being located on the Y axis.

[0033] Advantageously, the height 9 of the current collection tabs 7 decreases as one moves from the periphery 14 towards the center 15 of the cell 1.

[0034] Thus, the folding of the current collection tabs 7 is made easier and cleaner. Indeed, the folding of the current collection tabs 7 is more harmonious. Thus, it becomes possible to avoid the formation of an uncontrolled mass of metal at the ends 21 of the cell 1. This makes it possible to reduce the risks of short circuits, electrolyte leaks and accidents.

[0035] Advantageously, a first separation distance 22 between two current collection tabs 7 of a given series 6 are substantially identical. The first distance 22 is measured along the X axis.

[0036] This makes it possible to position the current collection tabs 7 of the same series 6 at an identical distance from each other in order to obtain a homogeneous distribution thereof. Thus, it is possible to obtain a desired pattern, for example that of [Fig.2]. These patterns respond to technical considerations.

[0037] Advantageously, the first distance 22 is different from one series to another. This makes it possible to obtain a desired pattern, for example that of [Fig.2]. Indeed, it is advantageous for the first distance 22 to differ from one series 6 to another to accommodate the position of a given series in the cylinder. An identical first distance would have the consequence of obtaining an angular offset between the series 6 and would not make it possible to obtain a desired pattern.

[0038] Advantageously, the first distance 22 is proportional to the height 9 of the current collection tabs 7 in a given series 6.

[0039] By making the first distance 22 proportional to the height 9 of the current collection tabs 7, the folding of the current collection tabs 7 is facilitated. The current collection tabs 7 located on the periphery 14 of the cylinder are higher in order to better cover the current collection tabs 7 located closer to the Y axis.

[0040] Advantageously, the first distance 22 decreases from one series 6 to the next depending on whether one moves along the first electrode 2 and the second electrode 3 towards the winding direction 19.

[0041] This makes it possible to obtain a desired pattern, for example that of [Fig.5]. Indeed, it is interesting that the first distance 22 differs from one series 6 to another to accommodate the position of a given series 6 in the cylinder.

[0042] Advantageously, a second distance 23 separates two neighboring series 6 of current collection tabs 7. The second distance 23 is measured along the X axis. The second distance 23 changes as one moves along the first electrode 2 and the second electrode 3. This makes it possible to obtain a desired pattern, for example that of [Fig.2]. Indeed, it is advantageous for the second distance 23 to change from one series 6 to the other to accommodate the position of a given series 6 in the cylinder.

[0043] Advantageously, the second distance 23 decreases as one moves along the first electrode 2 and in a winding direction 19. This makes it possible to obtain a desired pattern, for example that of [Fig.5]. Indeed, it is advantageous for the second distance 23 to decrease from one series 6 to another in the winding direction 19 to accommodate the position of a given series 6 in the cylinder.

[0044] Advantageously and according to an embodiment shown in [Fig.2], the collection tabs 7 have the shape of an isosceles trapezoid.

[0045] Such a shape facilitates the folding of the current collection tabs 7.

[0046] Advantageously, each current collection tab 7 comprises: - a first upper base 24 merged with the upper edge 4 of the first electrode 2 and a first lower base 25 merged with the lower edge 5 of the second electrode 3, - a second upper base 26 merged with the upper apex 8 of the first electrode 2 and a second lower base 27 merged with the lower apex 10 of the second electrode 3, - two upper lateral edges 32 connecting the first upper base 24 to the second upper base 26 and two lower lateral edges 33 connecting the first lower base 25 to the second lower base 27.

[0047] Advantageously, the first base 24, 25 has a first length 28 measured along the X axis and the second base 26, 27 has a second length 29 measured along the X axis. The second length 29 is less than the first length 28.

[0048] It is thus possible to obtain an isosceles trapezoid shape.

[0049] Advantageously, the first length 28 and the second length 29 have a ratio between 1 and 2. The ratio is calculated by dividing the first length 28 by the second length 29.

[0050] The inventors have determined that a ratio within this range is particularly advantageous in that it facilitates the folding of the current collection tabs 7 while avoiding the formation of a mass of metal.

[0051] Advantageously and according to an embodiment shown in [Fig. 1], the collection tabs 7 have a substantially rectangular shape.

[0052] In [Fig.l], the current collection tabs 7 of a given series 6 have a third given length 30, measured along the X axis. Thus, in a given series 6, the current collection tabs 7 have an identical third length 30.

[0053] Advantageously, from one series 6 to another, the third length 30 is different.

[0054] This makes it possible to obtain a desired pattern, for example that of [Fig.5], this pattern responding to technical considerations.

[0055] Advantageously, the third length 30 decreases as one moves towards the winding direction 19.

[0056] Advantageously, according to an alternative embodiment shown in Figures 3 and 4, each current collection tab 7 comprises a cutout 31 along the Y axis. The cutout 31 separates each current collection tab 7 into two half-tabs of substantially identical dimensions.

[0057] This makes it easier to fold the current collection tabs 7, since folding half-tabs turns out to be a less complex operation.

[0058] Advantageously, in the first electrode 2 the cutout 31 extends from the upper edge 4 to the upper apex 8. In the second electrode 3, the cutout 31 extends from the lower edge 5 to the lower apex 10.

[0059] This makes it possible to avoid the formation of a metal mass at the base of the current tabs 7. This also makes it possible to avoid the formation of ripples on the current collection tabs 7 when winding the electrodes.

Claims

Claims

1. Electric battery cell (1) for an electrically powered vehicle, said cell (1) comprising at least one successive stack of a sheet: - a first positive electrode (2) comprising an upper edge (4), - a first insulating separator, - a second negative electrode (3) comprising a lower edge (5), - a second insulating separator, said at least one stack being wound on itself around a central axis (Y) so as to form a cylinder, said first electrode (2) and said second electrode (3) each comprising at least two series (6) of current collection tabs (7), each series (6) comprising at least two current collection tabs (7), each of the current collection tabs (7) extending from the upper edge (4) in the first electrode (2) and from the lower edge (5) in the second electrode (3), to respectively an upper apex (8) and a lower apex (10),on a given height (9) measured along the central axis (Y), cell (1) in which in a given series (6) the current collection tabs (7) have a substantially identical height (9) and the height (9) of the current collection tabs (7) is different from one series (6) to another, cell in which a first separation distance (22) between two current collection tabs (7) of a given series (6) is substantially identical, the first distance (22) being measured along a first axis (X) substantially perpendicular to the central axis (Y) and parallel to the upper and lower edges (4, 5), the first distance (22) being different from one series (6) to another.,

2. Cell (1) according to claim 1 wherein the height (9) of the current collecting tabs (7) decreases as one moves along the first electrode (2) and the second electrode (3) and towards a winding direction (19).

3. Cell (1) according to any one of the preceding claims in which, once the stack is wound on itself around the central axis (Y), the cell (1) comprises several rows (20) of current collecting tabs (7), said rows (20) extending from a periphery (14) of the cell (1) towards a center (15) of said cell (1) located on the central axis (Y).

4. Cell (1) according to claim 3 wherein the height (9) of the current collection tabs (7) decreases as one moves from the periphery (14) towards the center (15).

5. Cell (1) according to any one of the preceding claims in which the first distance (22) is proportional to the height (9) of the current collection tabs (7) in a given series (6).

6. Cell (1) according to any one of the preceding claims wherein the first distance (22) decreases from one series (6) to the other depending on whether one moves along the first (2) electrode and the second (3) electrode towards a winding direction (19).

7. Cell (1) according to any one of the preceding claims, in which a second distance (23) separating two neighboring series (6) of current collection tabs (7) and measured along a first axis (X) substantially perpendicular to the central axis (Y) and parallel to the upper and lower edges (4, 5), said second distance (23) changing as one moves along the first electrode (2) and the second electrode (3).

8. Cell (1) according to claim 7 wherein the second distance (23) decreases as one moves along the first electrode (2) and the second electrode (3), towards a winding direction (19).

9. Cell (1) according to any one of the preceding claims in which the current collection tabs (7) have the shape of an isosceles trapezoid.

10. Cell (1) according to claim 9 in which the current collection tabs (7) comprise: - a first upper base (24) merged with the upper edge (4) of the first electrode (2) and a first lower base (25) merged with the lower edge (5) of the second electrode (3), - a second upper base (26) merged with the upper top (8) of the current collection tab (7) and a second lower base (27) merged with the lower top (10) of the current collection tab (7), - two upper lateral edges (32) connecting the first upper base (24) to the second upper base (26) and two lower lateral edges (33) connecting the first lower base (25) and the second lower base (27).

11. Cell (1) according to claim 10 in which the first base (24,25) has a first length (28) and the second base (26,27) has a second length (29) less than the first length (28), the first length (28) and the second length (29) being measured along the first axis (X).

12. Cell (1) according to claim 11 in which the first length (28) and the second length (29) have a ratio of between 1 and 2.

13. Cell (1) according to any one of the preceding claims in which the current collection tabs (7) have a substantially rectangular shape.

14. Cell (1) according to claim 9 in which the collection tabs (7) running from a given series (6) have a third given length (30), measured along the first axis (X).

15. Cell (1) according to claim 14 in which, from one series (6) to another, the third length (30) is different.

16. Cell (1) according to any one of claims 14 or 15 in which the third length (30) decreases as one moves towards a winding direction (19).

17. Cell (1) according to any one of the preceding claims, in which each current collection tab (7) comprises a cutout (31) along the central axis (Y), said cutout (31) separating each current collection tab (7) into two half-tabs of substantially identical dimensions.

18. Cell (1) according to claim 17 wherein, in the first electrode (2), the cutout (31) extends from the upper edge (4) to the upper apex (8) and in the second electrode (3), the cutout (31) extends from the lower edge (5) to the lower apex (10).

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