Battery cells for batteries and methods for manufacturing such cells

Abstract

A battery cell for an electric vehicle includes at least one continuous stack of the following sheets: a first electrode comprising a first inactive portion and a first active portion; the at least one stack is wound around itself about a central axis to form a cylinder; the first inactive portion includes at least two cuts to form a flexible current collector tab between the cuts; the cell includes a first current collector having at least a first support portion protruding from its inner surface along the central axis; the first support portion is intended to contact the current collector tab and hold the flexible current collector tab in a bent position; the support portion extends over a length (L) between a proximal end located on the same side as the central axis and a distal end located on the periphery of the first current collector; the length (L) is measured along a radial axis intersecting and substantially perpendicular to the central axis; the support portion has a height (H) decreasing from the periphery toward the central axis along the length (L).

Description

Technical Field

[0001] This invention relates to the field of batteries for electric vehicles. In particular, it relates to battery cells. More specifically, it relates to cylindrical battery cells. Background Technology

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

[0003] The advantage of cylindrical battery cells is that they can store a large amount of energy in a small volume. Therefore, given a certain energy storage capacity, cylindrical battery cells occupy less space in a vehicle.

[0004] The energy storage capacity of a cylindrical battery cell depends on its diameter. Therefore, the larger the diameter of a cylindrical battery cell, the greater its energy storage capacity.

[0005] Cylindrical battery cells are manufactured by continuously stacking at least the following components wound around a core axis:

[0006] - Positive electrode sheet

[0007] -Insulating separator sheet,

[0008] - Negative electrode sheet

[0009] - Insulating separator sheet.

[0010] Along the electrode sheets, current collector tabs are added, and then attached to the positive and negative electrode sheets. While this operation is automated, it is particularly time-consuming and slows down the production rate of cylindrical cells. Furthermore, attachment and / or contact defects between the tabs and electrodes can degrade the performance of cylindrical cells and even cause short circuits.

[0011] To overcome these problems, some manufacturers have proposed eliminating the tabs that are added and then attached to the electrodes.

[0012] One solution is to create cutouts directly on the electrode sheet to form current collector tabs, and then wind the electrode sheet around a rotating mandrel. After winding, these tabs bend and come into contact with the added current collector.

[0013] One drawback of this method is that a large number of slits need to be made in the cutting operation before the core is wound around the mandrel. As a result, the production speed of the battery cell is slowed down due to the large number of slits that must be made.

[0014] Another drawback of this method is that the collector tabs may be damaged during the winding process around the mandrel because they are very thin and easily damaged during manipulation.

[0015] Another drawback of this method is the difficulty in bending the tabs, partly due to the large number of tabs. Furthermore, attaching bent tabs is both time-consuming and technically challenging when the goal is to achieve industrial production speeds.

[0016] Therefore, the present invention aims to solve the above-mentioned problems. Summary of the Invention

[0017] Therefore, the present invention first provides a battery cell for an electric vehicle, the battery cell comprising at least one continuous stack of the following sheets:

[0018] - A first electrode, the first electrode comprising a first inactive portion and a first active portion coated with an active material.

[0019] -First insulating separator,

[0020] - A second electrode, comprising a second inactive portion and a second active portion coated with an active material.

[0021] -Second insulating separator,

[0022] The at least one stacked body is wound around itself about a central axis to form a cylinder. The cell includes a first end, from which a first inactive portion extends. In the cell, the first inactive portion includes at least two cutouts to form a flexible current collector tab between the cutouts. The cell includes a first current collector, which includes an inner surface facing the electrode and an outer surface opposite the inner surface. The current collector has a first support portion projecting from the inner surface at least along the central axis. The first support portion is designed to contact the current collector tab and hold the flexible current collector tab in a bent position.

[0023] In the cell, a support portion extends over a length between a proximal end located on the same side as the central axis and a distal end located on the side opposite the proximal end and on the periphery of the first current collector. This length is measured along a radial axis that passes through the support portion and intersects the central axis and is substantially perpendicular to it.

[0024] In the cell, the support portion has a height measured from the inner surface to the contact surface and along the central axis, the height decreasing along the length from the periphery toward the central axis.

[0025] Because the number of cuts is reduced while conductivity remains at an acceptable level, there is no loss in cell efficiency, allowing for industrial-scale production of this cell. The reduced number of collector tabs compared to existing cells makes bending easier. This results in a significantly lower scrap rate. Furthermore, the specific shape of the support portion ensures that the collector tabs bend along the central axis, facilitating correct bending simply by positioning the current collector. In other words, no pre-bending operation (e.g., pre-bending using additional tools before positioning the current collector) is required. Additionally, the formation of disordered metal clusters in the area of ​​the collector tabs is avoided.

[0026] Various additional features can be provided individually or in combination:

[0027] - The cell includes a second end opposite to the first end along a central axis, and a second inactive portion extends from the second end. In the cell, the second inactive portion includes at least two cuts to form a current collector tab between the cuts. The cell includes a second current collector, which is provided with at least a second support portion. The second support portion is designed to contact the flexible current collector tab and hold the flexible current collector tab in a bent position.

[0028] - The collector tabs overlap and bend from the periphery of the cell toward the central axis;

[0029] - At least a first support portion of the first current collector is fixed to the current collector tab of the first electrode, and at least a second support portion of the second current collector is fixed to the current collector tab of the second electrode;

[0030] - The cell includes multiple flexible current collector tabs that are separated from each other at each end, and the first current collector and the second current collector include multiple support portions that are separated from each other, each support portion being designed to contact a current collector tab portion in order to hold the current collector tab in a bent position.

[0031] - The current collector is a metal disc, the metal disc including an inner surface facing the electrode and an outer surface opposite to the inner surface, in the cell, at least one support portion protrudes from the inner surface along the central axis;

[0032] - The length of the cut extension is approximately equal to the length of the supporting portion;

[0033] - The inner surface is arranged at a certain distance from the electrodes;

[0034] -The appliances in the second episode are basically the same as those in the first episode.

[0035] Second, the present invention provides a battery comprising a plurality of cells as described above and a connector intended to interconnect the cells.

[0036] Third, the present invention provides a method for manufacturing a battery cell as described above, the method comprising:

[0037] -The operation of supplying a sheet of a first electrode comprising a first active portion and a first inactive portion.

[0038] -The operation of supplying sheets for the first insulating separator.

[0039] -The operation of supplying a sheet of second electrodes comprising a second active portion and a second inactive portion.

[0040] -The operation of supplying the sheet material for the second insulating separator.

[0041] - An operation of sequentially stacking a first electrode, a first insulating spacer, a second electrode, and a second insulating spacer to form a stack body, wherein the first electrode and the second electrode are laterally offset relative to each other, such that a first inactive portion and a second inactive portion at least partially extend from the stack body.

[0042] - An operation of wrapping a stack around itself to form a generally cylindrical shape, the cylinder including a first end and a second end, a first inactive portion extending from the first end beyond the stack, and a second inactive portion extending from the second end beyond the stack.

[0043] - The operation of cutting the first and second inactive portions after the winding operation to form the collector ear.

[0044] - The operation of arranging the first current collector and the second current collector on the first end and the second end respectively, such that at least one support portion contacts at least one current collector lug portion so as to bend the current collector lug.

[0045] The method includes welding the support portion of the current collector to the current collector ear. Attached Figure Description

[0046] Further features and advantages of the invention will become apparent from the following detailed description, taken with reference to the accompanying drawings, in which:

[0047] Figure 1 This is a schematic cross-sectional view of a portion of a cylindrical battery cell according to the present invention;

[0048] Figure 2 This is a schematic top view taken from above the current collector according to the invention;

[0049] Figure 3 yes Figure 2 A schematic cross-sectional view of the current collector shown;

[0050] Figure 4 This is a schematic top view taken from above the current collector according to the invention;

[0051] Figure 5 yes Figure 4 A schematic cross-sectional view of the current collector shown;

[0052] Figure 6 This is a schematic diagram of one end of the battery cell according to the present invention;

[0053] Figure 7 This is a schematic diagram of the other end of the battery cell according to the present invention. Detailed Implementation

[0054] Figure 1 A battery cell 1 is shown. This cell 1 is intended to power an electric vehicle. Cell 1 comprises at least one continuous stack of the following sheets:

[0055] -First electrode 2,

[0056] -First insulating separator 3,

[0057] -Second electrode 4,

[0058] -Second insulating separator 5.

[0059] The stack wraps itself around the central axis 8 to form a cylinder.

[0060] The first electrode 2 includes a first active portion 9 coated with an active material and a first inactive portion 10 uncoated with any active material. Therefore, the first inactive portion 10 is a metal, such as aluminum or copper.

[0061] The second electrode 4 includes a second active portion 11 coated with an active material and a second inactive portion 12 uncoated with any active material. Therefore, the second inactive portion 12 is a metal, such as aluminum or copper.

[0062] The cell 1 includes a first end 13. A first inactive portion 10 extends from the first end 13. "Extends" means that the first inactive portion 10 extends at least partially beyond the separators 3 and 5 along the central axis 8.

[0063] like Figure 6 and Figure 7 As shown, the first inactive portion 10 includes at least two cuts 14. In the embodiment shown in the figures, the first inactive portion 10 includes eight cuts 14, thereby forming four first tab portions 15. The cuts 14 allow for the formation of flexible current collector tabs 16.

[0064] The battery cell 1 includes a first current collector 17. The first current collector 17 includes at least a first support portion 18. The first support portion 18 is designed to contact a flexible current collector tab 16 and hold the flexible current collector tab in a bent position.

[0065] Because the number of cuts 14 is reduced while conductivity remains at an acceptable level, the efficiency of the cell 1 is not compromised, allowing for industrial-scale production of this type of cell 1. Since there are fewer collector tabs 14 compared to existing cells, bending is also easier. As a result, the scrap rate is significantly reduced.

[0066] Advantageously, the cell 1 includes a second end 19 opposite to the first end 13 along the central axis 8. A second inactive portion 12 extends from the second end 19. "Extends" means that the second inactive portion 12 extends beyond the separators 3 and 5 along the central axis 8.

[0067] Advantageously, the second inactive portion 12 includes at least two cuts 14, between which a current collector tab 16 is formed. In the embodiment shown in the figures, the second inactive portion 12 includes eight cuts 14, thereby forming four second tab portions 32.

[0068] Advantageously, the cell 1 includes a second current collector 20, which is provided with at least a second support portion 21. The second support portion 21 is designed to contact the flexible current collector tab 16 and hold the flexible current collector tab in a bent position.

[0069] To maintain production consistency, it is advantageous for the second end 19 to be identical to the first end 13. This simplifies the manufacturing process of cell 1.

[0070] Advantageously, such as Figure 1 As shown, the collector tabs 16 can be overlapped and bent. The collector tabs bend from the periphery 22 of the cell 1 toward the central axis 8.

[0071] Bending the collector tab 16 in this direction is advantageous because it avoids the risk of short circuits.

[0072] Advantageously, the first support portion 18 of the first current collector 17 is fixed to the current collector lug 16 of the first electrode 2. Advantageously, the second support portion 21 of the second current collector 20 is fixed to the current collector lug 16 of the second electrode 4. Their fixing is, for example, by welding.

[0073] By fixing only the support portions 18, 21 to the collector lug 16, the number of solder joints is reduced while maintaining acceptable conductivity. This increases production speed.

[0074] Advantageously, the first current collector 17 includes four first support portions 18 that are distinct from each other. Each first support portion 18 is designed to contact the first collector ear portion 15 and hold the collector ear 16 in a bent position.

[0075] Advantageously, the second current collector 20 includes four second support portions 21 that are distinct from each other. Each second support portion 21 is designed to contact the second current collector ear portion 32 and hold the current collector ear 16 in a bent position.

[0076] Advantageously, the first current collector 17 and the second current collector 20 are in the form of a metal disc. The metal disc includes an inner surface 23 facing the electrodes 2, 4 and an outer surface 24 opposite to the inner surface 23. Support portions 18, 21 protrude from the inner surface 23 along the central axis 8.

[0077] These support portions 18 and 21 ensure contact with the collector ear 16.

[0078] Advantageously, the first collector 17 and the second collector 20 are basically the same.

[0079] Advantageously, each support portion 18, 21 extends a length L. The length L is measured along a radial axis 25 passing through the support portions 18, 21. The radial axis 25 is substantially perpendicular to the central axis 8. The radial axis 25 intersects the central axis 8. The length L is measured along the radial axis 25, which is substantially perpendicular to the central axis 8, between the proximal end 26 located on the same side as the central axis 8 and the distal end 27 opposite to the proximal end 26. The distal end 27 is located on the same side as the periphery 22 of the cell 1. The length of the cutout 14 is substantially equal to the length L.

[0080] It should be noted that the number of radial axes 25 is the same as the number of support portions 18, 21. In this case, each support portion 18, 21 is associated with a radial axis 25 passing through the support portion 18, 21, which is substantially perpendicular to and intersects the central axis 8.

[0081] Since the lengths of the support portions 18 and 21 are substantially equal to the length of the cutout 14, the contact is optimal and the conductivity remains at an acceptable level.

[0082] Advantageously, the distance D1 between two adjacent cuts is less than or equal to 80% of the inner diameter D2. The inner diameter D2 corresponds to the outer diameter of the winding mandrel.

[0083] This distance D1 facilitates the bending of the collector ear 16.

[0084] Advantageously, the support portions 18, 21 of the current collector include a contact surface 28 intended to contact the current collector ear 16.

[0085] This allows for optimal conductivity.

[0086] Advantageously, the support portions 18 and 21 have a height H measured in a direction parallel to the central axis 8. The height H is the distance measured from the inner surface 23 to the contact surface 28 of the support portion. The height H decreases along the length L from the periphery 22 of the cell 1 toward the central axis 8.

[0087] This ensures that the collector tab 16 bends along the direction of the central axis 8, thus facilitating bending in the correct direction simply by positioning the current collectors 17 and 20. In other words, no pre-bending operation is required on the collector tab (e.g., pre-bending operation using additional tools before positioning the current collectors). Furthermore, the formation of disordered metal clusters in the area of ​​the collector tab is avoided.

[0088] Advantageously, the inner surfaces 23 of both the first current collector 17 and the second current collector 20 are arranged at a certain distance from the first electrode 2 and the second electrode 4, respectively. Therefore, there is no contact between the inner surfaces 23 and the inactive parts of the electrodes.

[0089] Advantageously, the first electrode portions 15 are arranged at 90° to each other. Therefore, the first electrode portions 15 form an included angle α of 90°.

[0090] Advantageously, the second electrode portions 32 are arranged at 90° to each other. Therefore, the second electrode portions 32 form an included angle α of 90°.

[0091] This achieves better conductivity by shortening the distance electrons travel through the electrode sheets. This improves the performance of the battery cell.

[0092] like Figure 1 As shown, the battery cell is assembled by inserting an assembly including a wound stack and a current collector into a rigid cylindrical casing 29. A second current collector 20 (as the negative electrode) is in contact with the cylindrical casing 29, and thus the cylindrical casing 29 is negatively polarized. Conversely, the first current collector 17 is positively polarized and does not directly contact the cylindrical casing 29. The battery cell 1 includes a cover 30, which is added to and attached to the first current collector 17, and thus positively polarized. Figure 1 As shown, insulating element 31 is arranged between the first current collector 17 and the cylindrical enclosure 29. Additional insulating element 31 is arranged between the cover 30 and the cylindrical enclosure 29. These insulating elements 31 prevent short circuits.

[0093] The present invention also relates to a battery comprising a plurality of cells 1 (not shown in the figure). The battery includes connectors designed to interconnect the cells.

[0094] The method used to manufacture this battery cell will be described below.

[0095] The method includes the operation of supplying the following components:

[0096] - A sheet of first electrode, comprising a first active portion and a first inactive portion.

[0097] -Sheet of the first insulating separator,

[0098] - A sheet of second electrode, comprising a second active portion and a second inactive portion.

[0099] -Sheet of the second insulating separator.

[0100] The method includes the operation of sequentially stacking a first electrode, a first insulating spacer, a second electrode, and a second insulating spacer. The stacking is performed such that:

[0101] - At the first end, the first inactive portion extends beyond the stack, and

[0102] - At the second end, the second inactive portion extends beyond the stack.

[0103] The method includes the operation of wrapping a stack around itself to form a generally cylindrical shape. Thus, at a first end of the cylinder, a first inactive portion extends from the stack, and at a second end of the cylinder, a second inactive portion extends from the stack.

[0104] The method includes a cutting operation following the winding operation. This cutting allows for the formation of collector tabs. In the embodiment shown in the figures, eight cuts are made to form four collector tab portions at each end of the cell.

[0105] The method includes arranging a first current collector and a second current collector on a first end and a second end, respectively. This arrangement is performed such that each support portion contacts a current collector tab portion. This contact tilts the current collector tab toward a central axis.

[0106] Because the number of slits is more optimized and there is no loss in cell efficiency, these cells can be produced at industrial speeds. Furthermore, since the slits are made after winding rather than before, the collector tabs are not damaged. Because there are fewer collector tabs compared to existing cells, bending is also easier. Therefore, the scrap rate is significantly reduced.

[0107] Advantageously, the method includes welding a support portion to the collector ear, thereby securing the current collector to the collector ear.

Claims

1. A battery cell (1) for an electric vehicle, said cell (1) comprising at least one continuous stack of sheets: - First electrode (2), the first electrode includes a first inactive portion (10) and a first active portion (9) coated with an active material. - First insulating separator (3). - Second electrode (4), the second electrode includes a second inactive portion (12) and a second active portion (11) coated with an active material. -Second insulating separator (5) The at least one continuous stacked body is wound around itself around a central axis (8) to form a cylinder. The cell (1) includes a first end (13) from which a first inactive portion (10) extends. In the cell (1), the first inactive portion (10) includes at least two first cuts to form a flexible first current collector tab between the first cuts. The cell includes a first current collector (17) which includes an inner surface (23) facing a first electrode and a second electrode, and an outer surface (24) opposite to the inner surface (23). The first current collector is provided with at least a first support portion (18) which protrudes from the inner surface (23) along the central axis (8). The first support portion (18) is intended to contact the flexible first current collector tab and hold the flexible first current collector tab in a bent position. In the cell, the first support portion (18) extends over a length (L) between a proximal end (26) located on the same side as the central axis (8) and a distal end (27) located on one side of the periphery (22) of the first current collector (17) opposite to the proximal end (26), the length (L) being measured along a radial axis (25) that passes through the first support portion (18) and intersects the central axis (8) and is substantially perpendicular to it. In the cell, the first support portion (18) has a height (H) measured from the inner surface (23) to the contact surface (28) and along the central axis (8), the height (H) decreasing from the periphery (22) toward the central axis (8) along the length (L).

2. The battery cell (1) according to claim 1, wherein, The cell includes a second end (19) opposite to the first end (13) along the central axis (8), and a second inactive portion (12) extends from the second end (19). In the cell (1), the second inactive portion (12) includes at least two second cuts to form a flexible second current collector ear between the second cuts. The cell (1) includes a second current collector (20) having at least a second support portion (21) designed to contact the flexible second current collector ear and hold the flexible second current collector ear in a bent position.

3. The battery cell (1) according to claim 1, wherein, The flexible first collector ear bends and overlaps each other from the periphery (22) of the cell (1) toward the central axis (8).

4. The battery cell (1) according to claim 2, wherein, The flexible first collector ear and the flexible second collector ear overlap and bend from the periphery (22) of the cell (1) toward the central axis (8).

5. The battery cell (1) according to claim 2 or 4, wherein, The first support portion (18) of the first current collector (17) is fixed to the flexible first current collector ear of the first electrode (2), and the second support portion (21) of the second current collector (20) is fixed to the flexible second current collector ear of the second electrode (4).

6. The battery cell (1) according to claim 5, wherein, The cell includes multiple flexible current collector portions (15, 32) that are distinct from each other at each end (13, 19), and the first current collector (17) includes multiple first support portions (18) that are distinct from each other, and the second current collector (20) includes multiple second support portions (21) that are distinct from each other. Each first support portion (18) and each second support portion (21) is intended to contact a current collector portion (15, 32) in order to hold the flexible first current collector and the flexible second current collector in a bent position, respectively.

7. The battery cell according to claim 5, wherein, The first current collector (17) and the second current collector (20) are metal discs, the metal discs including the inner surface (23) facing the first electrode and the second electrode and the outer surface (24) opposite to the inner surface (23), in the cell (1), the at least first support portion (18) and the at least second support portion (21) protrude from the inner surface (23) along the central axis (8).

8. The battery cell (1) according to claim 7, wherein, The lengths of the first incision and the second incision are equal to the length (L).

9. The battery cell (1) according to claim 7 or 8, wherein, The inner surface (23) is arranged at a certain distance from the first electrode and the second electrode.

10. The battery cell (1) according to claim 2 or 4, wherein, The second current collector (20) is the same as the first current collector (17).

11. A battery comprising a plurality of cells (1) according to any one of claims 1 to 10 and a connector intended to connect the cells to each other.

12. A method for manufacturing a battery cell according to any one of claims 1 to 10, the method comprising: -The operation of supplying a sheet of a first electrode comprising a first active portion and a first inactive portion. -The operation of supplying sheets for the first insulating separator. -The operation of supplying a sheet of second electrodes comprising a second active portion and a second inactive portion. -The operation of supplying the sheet material for the second insulating separator. - An operation of sequentially stacking the first electrode, the first insulating spacer, the second electrode, and the second insulating spacer to form a stack body, wherein the first electrode and the second electrode are laterally offset relative to each other, such that the first inactive portion and the second inactive portion at least partially extend from the stack body. - The operation of wrapping the stack around itself to form a generally cylindrical shape, the cylinder including a first end and a second end, the first inactive portion extending from the first end beyond the stack, and the second inactive portion extending from the second end beyond the stack. - The operation of cutting the first inactive portion and the second inactive portion after the winding operation to form the flexible first collector ear and the flexible second collector ear, respectively. - The operation of arranging the first current collector and the second current collector on the first end and the second end respectively, such that at least one first support portion and at least one second support portion contact at least one current collector ear portion, so as to bend the flexible first current collector ear and the flexible second current collector ear.

13. The method according to claim 12, wherein, The method includes welding the first support portion and the second support portion of each of the first current collector and the second current collector to the flexible first current collector ear and the flexible second current collector ear, respectively.

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