Cell for a battery and method for producing said cell

Abstract

The invention relates to a cell (1) for a battery of an electric vehicle, the cell (1) comprising at least one continuous stack of the following sheets: a first electrode (2) comprising a first inactive part (10) and a first active part (9) coated with an active material; a first insulating separator (3); a second electrode (4) comprising a second inactive portion (12) and a second active portion (11) coated with an active material; the invention relates to a battery (1) comprising at least one stack (2) comprising a first insulating separator (3) and a second insulating separator (5), said at least one stack being wound onto itself about a central axis (8) so as to form a cylinder, the battery cell (1) comprising a first end (13) from which a first inactive portion (10) protrudes, the first inactive portion (10) comprising at least two cutouts (14) in the battery cell (1) so as to form a bendable collector tab (16) between the cutouts (14), the cell comprises a first current collector (17) comprising an inner face (23) arranged facing the electrodes and an outer face (24) opposite the inner face (23), the current collector being provided with at least a first bearing portion (18) projecting from the inner face (23) along the central axis (8), the first bearing portion (18) being intended to be in contact with the collector tab (16) and to maintain the bendable collector tab (16) in a bent position, the first bearing portion (18) being provided with a second bearing portion (18), the second bearing portion (18) being provided with a second bearing portion (18), the second bearing portion (18) being provided with a second bearing portion (18), in the cell, the 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) opposite the proximal end (26) and located on the side of the periphery (22) of the first current collector (17), the length (L) measured along a radial axis (25) passing through the support portion (18) and intersecting and substantially perpendicular to the central axis (8), the bearing portion (18) has a height (H) measured from the inner face (23) to the contact face (28) and along the central axis (8), the height (H) decreasing along the length (L) from the periphery (22) towards the central axis (8).

Description

Technical Field

[0001] The present invention relates to the field of batteries for electric vehicles. In particular, the present invention relates to battery cells. More specifically, the present invention relates to cylindrical battery cells. Background Art

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

[0003] The advantage of cylindrical cells is that they can store a lot of energy in a small volume. Therefore, for a given energy storage capacity, cylindrical cells take up less space in the vehicle.

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

[0005] Cylindrical cells are made by winding a continuous stack of at least the following components around a mandrel:

[0006] - positive electrode sheet,

[0007] - Insulating separator sheets,

[0008] - negative electrode sheet,

[0009] - Insulating separator sheets.

[0010] Along the electrode sheets, collector tabs are added and then attached to the positive and negative electrode sheets. While this operation can be automated, it is extremely time-consuming and can slow the production of cylindrical cells. Furthermore, defects in the attachment and / or contact between the tabs and the electrodes can degrade the performance of the 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 make cuts directly in the electrode sheet to form the collector tabs, which are then wound around a rotating mandrel. After winding, these tabs bend and come into contact with the added current collector.

[0013] A disadvantage of this method is that a large number of cuts need to be made in the cutting operation performed before winding around the mandrel. As a result, the production speed of the battery cell is slowed down by the large number of cuts that must be made.

[0014] Another disadvantage of this method is that the collector lugs may be damaged during the winding process around the mandrel, as they are thin and easily damaged during handling operations.

[0015] Another drawback of this method is that it is difficult to bend the tabs, partly due to the large number of tabs. Moreover, when the goal is to achieve industrial production speeds, attaching the tabs in a bent position is time-consuming and technically difficult.

[0016] SUMMARY OF THE INVENTION Therefore, the present invention is intended to solve the above-mentioned problems. Summary of the Invention

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

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

[0019] - a first insulating spacer,

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

[0021] - a second insulating spacer,

[0022] The at least one stack is wound onto itself around a central axis so as to form a cylinder, the battery cell comprises a first end portion from which a first inactive portion projects, in the battery cell, the first inactive portion comprises at least two cutouts so as to form a bendable collector lug between the cutouts, the battery cell comprises a first current collector, the first current collector comprises an inner face facing the electrode arrangement and an outer face opposite the inner face, the current collector being provided with a first support portion protruding from the inner face at least along the central axis, the first support portion being intended to contact the collector lug and to maintain the bendable collector lug in a bent position,

[0023] In the battery cell, the support portion extends over a length between a proximal end located on the same side as the central axis and a distal end opposite to the proximal end and located on a side of the periphery of the first current collector, the length being measured along a radial axis passing through the support portion and intersecting the central axis and being substantially perpendicular thereto,

[0024] In the battery 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 a length from the periphery toward the central axis.

[0025] Because the number of cuts is reduced while the conductivity remains at an acceptable level, there is no loss in cell efficiency, making it possible to produce such cells at industrial speeds. Since the number of collector tabs is smaller than in existing cells, bending is easier. As a result, the scrap rate is significantly reduced. In addition, the specific shape of the support portion ensures that the collector tab is bent in the direction of the central axis, which helps to bend in the correct direction simply by positioning the current collector. In other words, there is no need to pre-bend the collector tab (for example, a pre-bending operation performed using an additional tool before positioning the current collector). In addition, the formation of disordered metal clusters in the area of the collector tab is avoided.

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

[0027] The battery cell comprises a second end portion opposite the first end portion along the central axis, a second inactive portion extending from the second end portion, wherein the second inactive portion comprises at least two cutouts in the battery cell so as to form a collector tab between the cutouts, the battery cell comprising a second current collector, the second current collector being provided with at least a second support portion, the second support portion being intended to contact the bendable collector tab and to hold the bendable collector tab in a bent position;

[0028] - The collector ears are bent 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 collector lug of the first electrode, and at least a second support portion of the second current collector is fixed to the collector lug of the second electrode;

[0030] - the cell comprises, at each end, a plurality of mutually distinct bendable collector tabs, and the first current collector and the second current collector comprise a plurality of mutually distinct support portions, each support portion being intended to come into contact with one collector tab portion in order to hold the collector tab in a bent position;

[0031] The current collector is a metal disk comprising an inner surface arranged facing the electrode and an outer surface opposite the inner surface, wherein in the battery cell, at least one support portion protrudes from the inner surface along a central axis;

[0032] - the length of the cutout extending substantially equal to the length of the support portion;

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

[0034] - The second current collector is essentially the same as the first current collector.

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

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

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

[0038] - an operation of supplying a sheet of a first insulating separator,

[0039] - an operation of supplying a sheet of a second electrode comprising a second active portion and a second inactive portion,

[0040] - an operation of supplying a sheet of the second insulating separator,

[0041] - an operation of successively stacking a first electrode, a first insulating separator, a second electrode, and a second insulating separator to form a stack in which the first electrode and the second electrode are laterally offset relative to each other so that the first inactive portion and the second inactive portion at least partially protrude from the stack,

[0042] an operation of winding the stack onto itself so as to form a substantially cylindrical body comprising a first end, the first inactive portion projecting outside the stack from the first end, and a second inactive portion projecting outside the stack from the second end,

[0043] - an operation of cutting the first inactive portion and the second inactive portion after the winding operation in order to form a collector lug,

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

[0045] The method includes the operation of welding a support portion of the current collector to a collector lug. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0048] Figure 2 is a schematic top view viewed from above of a current collector according to the present invention;

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

[0050] Figure 4 is a schematic top view viewed from above of a current collector according to the present invention;

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

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

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

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

[0055] - a first electrode 2,

[0056] - a first insulating spacer 3,

[0057] - a second electrode 4,

[0058] - a second insulating spacer 5 .

[0059] The stack is wound onto itself around a central axis 8 so as to form a cylinder.

[0060] The first electrode 2 comprises a first active portion 9 coated with an active material and a first inactive portion 10 not coated with any active material. Thus, the first inactive portion 10 is a metal, such as aluminum or copper.

[0061] The second electrode 4 comprises a second active portion 11 coated with an active material and a second inactive portion 12 not coated with any active material. Therefore, the second inactive portion 12 is a metal, such as aluminum or copper.

[0062] The cell 1 comprises a first end 13. The first inactive portion 10 projects from the first end 13. By "projecting" is meant that the first inactive portion 10 at least partially extends beyond the separators 3,5 along the central axis 8.

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

[0064] The cell 1 comprises a first current collector 17. The first current collector 17 comprises at least a first support portion 18. The first support portion 18 is intended to come into contact with the bendable collector tab 16 and to hold said bendable collector tab in a bent position.

[0065] Because the number of cutouts 14 is reduced while maintaining acceptable conductivity, the efficiency of the battery cell 1 is not compromised, allowing production of this type of battery cell 1 at industrial speeds. Since the number of collector tabs 14 is reduced compared to existing cells, bending is also easier. As a result, the scrap rate is significantly reduced.

[0066] Advantageously, the cell 1 comprises a second end 19 opposite the first end 13 along the central axis 8. The second inactive portion 12 projects from this second end 19. By "projecting" is meant that the second inactive portion 12 extends beyond the separators 3,5 along the central axis 8.

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

[0068] Advantageously, the cell 1 comprises a second current collector 20 provided with at least a second support portion 21. The second support portion 21 is intended to come into contact with the bendable collector tab 16 and to maintain said bendable collector tab in a bent position.

[0069] In order to maintain production consistency, it is advantageous for the second end 19 to be identical to the first end 13. This simplifies the method for manufacturing the battery cell 1.

[0070] Advantageously, as Figure 1 As shown, the collector tabs 16 can be bent over each other and overlap each other. The collector tabs are bent from the periphery 22 of the battery cell 1 toward the central axis 8 .

[0071] Bending the collector lug 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 collector lug 16 of the first electrode 2. Advantageously, the second support portion 21 of the second current collector 20 is fixed to the collector lug 16 of the second electrode 4. Their fixing is, for example, welding.

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

[0074] Advantageously, the first current collector 17 comprises four mutually distinct first support portions 18. Each first support portion 18 is intended to come into contact with a first collector lug portion 15 and to hold the collector lug 16 in a bent position.

[0075] Advantageously, the second current collector 20 comprises four mutually distinct second support portions 21. Each second support portion 21 is intended to come into contact with a second collector lug portion 32 and to hold the collector lug 16 in a bent position.

[0076] Advantageously, the first and second current collectors 17, 20 are in the form of metal disks comprising an inner face 23 arranged facing the electrodes 2, 4 and an outer face 24 opposite the inner face 23. The support portions 18, 21 project from the inner face 23 along the central axis 8.

[0077] These support portions 18 , 21 ensure contact with the collector lug 16 .

[0078] Advantageously, the first current collector 17 and the second current collector 20 are substantially identical.

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

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

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

[0082] Advantageously, the distance D1 separating two adjacent cutouts 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] Such a distance D1 facilitates the bending of the collector tab 16 .

[0084] Advantageously, the supporting portion 18 , 21 of the current collector comprises a contact surface 28 intended to come into contact with the current collector lug 16 .

[0085] This allows optimal electrical conductivity to be maintained.

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

[0087] This ensures that the collector tab 16 bends in the direction of the central axis 8, thereby facilitating bending in the correct direction simply by positioning the current collectors 17, 20. In other words, there is no need to pre-bend the collector tab (e.g., using an additional tool before positioning the current collector). Furthermore, the formation of disordered metal clusters in the area of the collector tab is avoided.

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

[0089] Advantageously, the first tab portions 15 are arranged at an angle of 90° to each other, thus forming an angle α of 90° between the first tab portions 15 .

[0090] Advantageously, the second tab portions 32 are arranged at an angle of 90° to each other, thus forming an angle α of 90° between the second tab portions 32 .

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

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

[0093] The invention also relates to a battery (not shown in the figures) comprising a plurality of cells 1. The battery comprises connectors intended to interconnect the cells.

[0094] Hereinafter, a method for manufacturing the battery cell will be described.

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

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

[0097] - a sheet of a first insulating separator,

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

[0099] - A sheet of second insulating separator.

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

[0101] - at the first end, the first inactive portion projects outside the stack, and

[0102] At the second end, the second inactive portion projects outside the stack.

[0103] The method comprises the operation of winding the stack onto itself to form a generally cylindrical body. 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 comprises a cutting operation after the winding operation. The cuts allow the formation of the collector tabs. In the embodiment shown in the drawings, eight cuts are made to form four collector tab portions on each end of the cell.

[0105] The method includes placing a first current collector and a second current collector on the first end and the second end, respectively. The placement is performed so that each support portion contacts a collector lug portion. This contact tilts the collector lug toward the central axis.

[0106] Because the number of cuts is more reasonable without sacrificing cell efficiency, these cells can be produced at industrial speeds. Furthermore, because the cuts are made after winding, rather than before, the collector tabs are not damaged. Since there are fewer collector tabs than in existing cells, bending is also easier. Consequently, scrap rates are significantly reduced.

[0107] Advantageously, the method comprises the operation of welding the support portion to the collector lug, thereby securing the current collector to said collector lug.

Claims

1. A battery cell (1) for a battery of an electric vehicle, the battery cell (1) comprising at least one continuous stack of the following sheets: - a first electrode (2) comprising a first inactive portion (10) and a first active portion (9) coated with an active material, - a first insulating spacer (3), - a second electrode (4) comprising a second inactive portion (12) and a second active portion (11) coated with an active material, - a second insulating spacer (5), The at least one continuous stack is wound around a central axis (8) so as to form a cylinder, the battery cell (1) comprising a first end (13) from which the first inactive portion (10) projects, in the battery cell (1) the first inactive portion (10) comprising at least two cutouts (14) so as to form a bendable collector lug (16) between the cutouts (14), the battery cell comprising a first current collector (17), the first current collector comprising an inner face (23) arranged facing the electrode and an outer face (24) opposite the inner face (23), the first current collector being provided with at least a first support portion (18) projecting from the inner face (23) along the central axis (8), the first support portion (18) being intended to come into contact with the bendable collector lug (16) and to hold the bendable collector lug (16) in a bent position, In the battery 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) opposite the proximal end (26) and located on one side of the periphery (22) of the first current collector (17), the length (L) being measured along a radial axis (25) passing through the first support portion (18) and intersecting the central axis (8) and being substantially perpendicular thereto, In the battery 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), and the height (H) decreases along the length (L) from the periphery (22) toward the central axis (8).

2. The battery cell (1) according to claim 1, wherein: The battery cell comprises a second end (19) opposite to the first end (13) along the central axis (8), the second inactive portion (12) extending from the second end (19), in the battery cell (1), the second inactive portion (12) comprises at least two cutouts (14) so as to form a collector lug (16) between the cutouts (14) of the second inactive portion, the battery cell (1) comprising a second current collector (20), the second current collector being provided with at least a second support portion (21), the second support portion being intended to contact the bendable collector lug (16) and to maintain the bendable collector lug in a bent position.

3. The battery cell (1) according to any one of claims 1 and 2, wherein: The collector ears (16) are bent and overlapped with each other from the periphery (22) of the battery core (1) toward the central axis (8).

4. The battery cell (1) according to any one of claim 2 and claim 3 in combination with claim 2, wherein: The at least first support portion (18) of the first current collector (17) is fixed to the collector lug (16) of the first electrode (2), and the at least second support portion (21) of the second current collector (20) is fixed to the collector lug (16) of the second electrode (4).

5. The battery cell (1) according to claim 4, wherein: The cell comprises a plurality of mutually distinct bendable collector lug portions (15, 32) at each end portion (13, 19), and the first current collector (17) and the second current collector (20) comprise a plurality of mutually distinct support portions (18, 21), each support portion (18, 21) being intended to contact one collector lug portion (15, 32) in order to maintain the collector lug (16) in a bent position.

6. The battery cell according to any one of claims 4 and 5, wherein: The current collector (17, 20) is a metal disk comprising an inner surface (23) arranged facing the electrodes (2, 3) and an outer surface (24) opposite to the inner surface (23), wherein in the battery cell (1), at least one support portion (18, 21) protrudes from the inner surface (23) along the central axis (8).

7. The battery cell (1) according to claim 6, wherein: The cutout (14) extends over a length substantially equal to the length (L).

8. The battery cell (1) according to any one of claims 6 and 7, wherein: The inner surface (23) is arranged at a distance from the electrodes (2, 4).

9. The battery cell (1) according to claim 2 or any one of claims 3 to 8 in combination with claim 2, wherein: The second current collector (20) is substantially identical to the first current collector (17).

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

11. A method for manufacturing a battery cell according to any one of claims 1 to 9, the method comprising: - an operation of supplying a sheet of a first electrode comprising a first active portion and a first inactive portion, - an operation of supplying a sheet of a first insulating separator, - an operation of supplying a sheet of a second electrode comprising a second active portion and a second inactive portion, - an operation of supplying a sheet of the second insulating separator, - an operation of successively stacking the first electrode, the first insulating separator, the second electrode, and the second insulating separator to form a stack in which the first electrode and the second electrode are laterally offset relative to each other so that the first inactive portion and the second inactive portion at least partially protrude from the stack, an operation of winding the stack onto itself so as to form a substantially cylindrical body, the cylindrical body comprising a first end and a second end, the first inactive portion projecting out of the stack from the first end and the second inactive portion projecting out of the stack from the second end, - an operation of cutting said first inactive portion and said second inactive portion after the winding operation so as to form a collector lug, - an operation of arranging the first and second current collectors on the first and second end portions, respectively, such that at least one support portion is in contact with at least one collector lug portion in order to bend the collector lug.

12. The method according to claim 11, wherein The method includes the operation of welding a support portion of a current collector to the current collector lug.

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