Cylindrical battery cell and method of manufacturing the same

Abstract

The invention relates to a battery cell (1) comprising at least one continuous stack of sheets of a first electrode (10), a first insulating separator (15), a second electrode (20) and a second insulating separator (25), the cell (1) comprising at least one current collector (60) comprising a metal plate, the current collector (60) comprising at least one recess (61) defining a passage in the metal plate and having an open profile, wherein at least one electrode of the cell (1) comprises a plurality of series (52), each series comprising a plurality of current collecting tabs (50) configured to collect an electric current delivered by the at least one electrode, the series (52) being inserted into the at least one recess (61) and in contact with the metal plate, thereby forming an electrical connection between the at least one electrode and the current collector (60).

Description

TECHNICAL FIELD

[0001] The present invention relates to cylindrical battery cells and to a method for manufacturing such battery cells. BACKGROUND

[0002] In the field of secondary batteries, and in particular batteries for electric vehicles, it is known to manufacture so-called cylindrical battery cells. Typically, such a battery cell comprises two electrodes: an anode and a cathode in the form of a sheet. These electrodes are then wound around a winding mandrel to form a generally cylindrical winding. Between the anode and the cathode, a porous insulating separator is arranged, which is configured to prevent a short circuit between the two electrodes and to allow the circulation of ions. The main winding is then inserted into a casing filled with an electrolyte, which serves to transport ions between the two electrodes.

[0003] The electrode sheet comprises an active portion coated with an active material and a metal portion not coated with an active material. The metal portion, which is free of active material, can be cut to form a current collecting tab. Thus, once wound, the winding comprises, on one side, a tab electrically connected to the anode and, on the other side, a tab electrically connected to the cathode.

[0004] The tabs make it possible to establish an electrical connection between different areas of the same electrode, to optimize current collection.

[0005] In order to collect all the current originating from each tab, it is known to deposit and weld a current collector onto said tab.

[0006] The electrical connection between the current collector and the current collecting tab is achieved by positioning a contact surface of the current collector on the current collecting tab and then applying a weld on the face opposite the contact surface. Although this technique makes it possible to collect current from the cell, it is a source of defects, sometimes requiring the rejection of the cell, and thus needs to be improved.

[0007] During assembly, the current collector is applied to the tab, then the contact surface is brought against the tab, causing it to bend. Thus, the bending is carried out in a random manner and it is not possible to determine a determined orientation and / or distribution of the tab under the current collector. The accumulation of tabs can form at various local positions, and thus certain areas of the current collector can not be in contact with the tab. Current collection by the current collector then becomes uneven and the weld performed over the areas where there is no tab is ineffective, if not useless, thereby compromising the overall performance of the cell.

[0008] There is therefore a need to find a reliable, practical and inexpensive method of electrically connecting the tab to the current collector. SUMMARY

[0009] The object of the present invention is to provide a solution to all or part of the problems mentioned above, namely:

[0010] - Provides a battery cell in which tabs are visibly welded to a current collector;

[0011] - Increase the number of welding techniques that can be performed during the welding phase;

[0012] - Reduce production costs;

[0013] - Reduce the number of defective units.

[0014] This objective can be achieved by implementing a battery cell for electric vehicles, the cell comprising at least one stack consisting of a continuous stack of the following sheets:

[0015] -First electrode;

[0016] -First insulating partition;

[0017] - The second electrode has a polarity opposite to that of the first electrode;

[0018] -Second insulating partition;

[0019] Stacks are wound around themselves around a winding axis to form a generally cylindrical winding. The unit includes at least one current collector, which includes a conductive metal plate having a contact surface facing the winding and a welding surface opposite the contact surface. The current collector includes at least one recess that defines a channel in the metal plate that opens on either side of the metal plate on both the contact surface and the welding surface. The recess has an opening profile.

[0020] A battery wherein at least one electrode selected from a first electrode and a second electrode comprises a plurality of series connections, each series connection comprising a plurality of current collector tabs configured to collect current from the at least one electrode, the series connections being inserted into the at least one recess to pass through a metal plate on either side thereof, the series connections contacting the metal plate to ensure electrical connection between the at least one electrode and the current collector.

[0021] The above arrangement allows for visualization of the welding of the current collector tabs during implementation. This further enables the use of more different types of welding and simplifies the manufacturing process.

[0022] The unit may also have one or more of the following features, either individually or in combination.

[0023] According to one embodiment, the current collector includes two to eight recesses.

[0024] In this way, the number of recesses can be adjusted according to the distribution of the current collector tabs around the winding axis.

[0025] According to one embodiment, the current collector includes four recesses.

[0026] Advantageously, the presence of four recesses allows for an optimal trade-off between efficient current collection guaranteed by a large number of recesses and manufacturing simplicity.

[0027] According to one embodiment, the recesses are angularly distributed around the winding axis in a constant manner.

[0028] In this way, current can be collected in a uniform distribution around the winding axis.

[0029] According to one embodiment, a given series of current collector tabs are aligned substantially along at least one radial direction perpendicular to the winding axis, the number of radial directions being equal to the number of recesses. Generally, a series connection of current collector tabs includes all current collector tabs aligned along the same radial direction.

[0030] In this way, at least one recess can be associated with each of the series of current collector bumps to collect all the current collected by the current collector bumps.

[0031] According to one embodiment, each recess has a width that is substantially perpendicular to the radial direction, which is significantly greater than the maximum width of a current collector tab aligned along the radial direction, the maximum width being substantially perpendicular to the radial direction.

[0032] In this way, it can be ensured that the current collector tabs can easily pass through each recess.

[0033] According to one embodiment, a current collector tab connected in series with the same type is soldered together. Typically, given current collector tabs connected in series are only soldered to each other to form an assembly consisting solely of the current collector tabs.

[0034] In this way, the cohesion between the current collector tabs can be increased, making it easier for them to be inserted into the recess, while also improving the electrical connection between them and the mechanical strength of the current collector tab assembly welded together.

[0035] According to one embodiment, the current collector tab passing through the at least one recess is folded onto the welding surface of the current collector and makes close contact with the welding surface.

[0036] This allows for an increase in the contact area between the current collector tab and the current collector, thereby improving the electrical connection between them.

[0037] According to one embodiment, a current collector tab folded onto a welding surface is welded to the welding surface.

[0038] In a coordinated manner, welding the current collector tabs to the current collector ensures a good electrical connection while improving the mechanical cohesion between the current collector and the winding.

[0039] The object of the present invention can also be achieved by implementing a method for manufacturing the unit as described above, the manufacturing method comprising:

[0040] - A step of providing a winding, wherein the collector lugs extend longitudinally along the winding axis;

[0041] -Provide the steps for using a current collector;

[0042] - Insertion step, wherein the current collector tab of the winding is inserted into at least one recess of the current collector so as to pass through the current collector on either side of the current collector and ensure electrical connection between the first electrode or the second electrode and the current collector.

[0043] This makes it easier to manufacture cylindrical battery cells by visualizing the current collector during the welding of the current collector tabs.

[0044] The manufacturing method may also have one or more of the following features, either individually or in combination.

[0045] According to one embodiment, the method further includes a welding step performed prior to the insertion step, during which all or part of the current collector tabs aligned in the same radial direction are welded together.

[0046] This makes it easier to implement the insertion step.

[0047] According to one embodiment, the method further includes a bending step performed after the insertion step, wherein the current collector tab passing through at least one recess is bent to make close contact with the welding surface of the current collector.

[0048] This ensures a good electrical connection between the tab and the current collector.

[0049] According to one embodiment, the method further includes a secondary welding step performed after the bending step, wherein the bent current collector tab is welded to the welding surface of the current collector.

[0050] Therefore, the mechanical cohesion of the entire cylindrical battery cell assembly can be improved. Attached Figure Description

[0051] Other aspects, objects, advantages, and features of the invention will become more apparent after reading the following detailed description of preferred embodiments of the invention, given by way of non-limiting example and with reference to the accompanying drawings, in which:

[0052] Figure 1 This is a schematic diagram of the components of a winding according to an embodiment of the present invention.

[0053] Figure 2 This is a schematic diagram of a battery cell according to an embodiment of the present invention.

[0054] Figure 3 yes Figure 2 A schematic diagram of the battery cell.

[0055] Figure 4 This is a schematic diagram of a current collector for a battery cell according to a specific embodiment of the present invention. Detailed Implementation

[0056] Throughout the accompanying drawings and description, the same reference numerals denote the same or similar elements. Furthermore, for clarity of the drawings, various elements are not shown to scale. Moreover, different embodiments and variations are not mutually exclusive and can be combined with each other.

[0057] like Figures 1 to 3 As shown, the present invention relates to a battery cell 1 for an electric vehicle, the cell 1 comprising at least one continuous stack of the following sheets:

[0058] -First electrode 10;

[0059] -First insulating partition 15;

[0060] - The second electrode 20 has a polarity opposite to that of the first electrode 10;

[0061] -Second insulating partition 25.

[0062] like Figure 1 As shown, the first electrode 10 may specifically comprise a first metal sheet 11 in the form of a thin strip, on which a layer of a first active material 13 is deposited. If the first electrode is an anode, the first metal sheet 11 may comprise copper. The first active material layer 13 is typically coated over the entire length of the first metal sheet 11, except for the peripheral strips that are not coated with active material.

[0063] Similarly, the second electrode 20 may include a second metal sheet 21 in the form of a thin strip, on which a second active material layer 23 is deposited. When the second electrode is a cathode, the second metal sheet 21 may include aluminum. The second active material layer 23 is typically coated over the entire length of the second metal sheet 21, except for the peripheral strips without active material coating.

[0064] Between each of the electrodes 10 and 20, spacer strips 15 and 25 are arranged such that there is no electrical contact between the first electrode 10 and the second electrode 20. Furthermore, the first electrode 10 and the second electrode 20 are generally offset along a winding axis indicated by "X", such that the area without active material coating is offset on either side of the spacer strips 15 and 25.

[0065] like Figure 1 As schematically shown, the stack is wound around itself around the winding axis X to form a generally cylindrical winding 30.

[0066] In the winding 30, at least one electrode selected from the first electrode 10 and the second electrode 20 includes a plurality of series 52, each series 52 including a plurality of current collector tabs 50 configured to collect current originating from said at least one electrode. Furthermore, as... Figure 1 and Figure 2 As shown, both the first electrode 10 and the second electrode 20 typically include a series connection 52 of current collector tabs 50. The current collector tabs 50 are typically arranged on the peripheral edges 12, 22 of the metal support sheets 11, 21 that do not contain active material. In this way, all current originating from the current collector tabs 50 connected to the same electrode can be collected on the same side of the winding 30.

[0067] The current collector tabs 50 of a given series 52 can be substantially aligned along at least one radial direction R perpendicular to the winding axis X. "Alignment" means that the current collector tabs overlap at an angle. Typically, the series 52 of current collector tabs 50 includes all current collector tabs 50 aligned along the same radial direction R.

[0068] Typically, each current collector tab 50 extends between the proximal end 51 and the free distal end 53 of the winding 30. When both the first electrode 10 and the second electrode 20 include current collector tabs 50, it is advantageous that the current collector tab 50 of the first electrode 10 is arranged on a first side of the winding 30, and the current collector tab 50 of the second electrode 20 is arranged on a second side of the winding 30 opposite to the first side. In other words, the current collector tabs 50 of each electrode 10, 20 are oriented in opposite directions. This allows any risk of electrical connection between the two electrodes 10, 20 to be avoided.

[0069] like Figures 2 to 4 As shown, unit 1 includes at least one current collector 60, which includes a conductive metal plate having a contact surface s60c facing the winding 30 and a welding surface s60s opposite the contact surface s60b. The metal plate may have an overall circular outline, or an outline inscribed within a circle, such that the current collector 60 has a generally disk-shaped configuration. Generally, as... Figure 2 As shown, current collectors 60 can be arranged on each side of winding 30. Thus, a first current collector 60 can collect current originating from the current collector tab 50 belonging to the first electrode 10, and a second current collector 60 can collect current originating from the current collector tab 50 belonging to the second electrode 20. In the description, current collector 60 is sometimes referred to, but it is understood that the provisions applicable to this current collector 60 can be applied to multiple current collectors 60.

[0070] The current collector 60 includes at least one recess 61 that defines a channel opening on either side of the metal plate on both the contact surface s60c and the welding surface s60s, the recess 61 having an open shape. The recess 61, in the form of a notch or cut, partially facilitates the removal or extraction of material relative to the rest of the metal plate of the current collector 60. Figure 2 and Figure 3 As shown, the opening shape of the recess 61 includes an opening facing the outside of the current collector 60. In other words, the recess 61 opens outward at the outer peripheral edge of the metal plate of the current collector 60.

[0071] Alternative locations, such as Figure 4 As shown, the opening shape of the recess 61 includes an opening oriented toward a central opening defined by the metal plate of the current collector 60. In other words, the recess 61 opens toward the interior of the metal plate of the current collector 60 at the central opening and at the inner peripheral edge that defines the central opening.

[0072] Each of these two variations allows for a reduction in the amount of material used to manufacture the current collector 60, while still permitting electrical connection to the series connection 52 including the current collector tab 50. Therefore, it is possible to facilitate welding the current collector 60 to the series connection 52 of the current collector tab 50 while limiting the amount of material used to manufacture the current collector 60.

[0073] like Figure 2 and Figure 3 As shown, series 52 is inserted into the at least one recess 61 to pass through the metal plate on either side. Thus, series 52 contacts the metal plate to ensure electrical connection between the at least one electrode and the current collector 60.

[0074] As shown in the figure, the current collector 60 may include two to eight recesses 61. In this way, the number of recesses 61 can be adjusted according to the distribution of the series connections 52 around the winding axis X. More specifically, the current collector 60 may include four recesses 61. Advantageously, the presence of four recesses 61 allows for an optimal trade-off between efficient current collection ensured by a large number of recesses 61 and manufacturing simplicity. Furthermore, while not limiting, it can be advantageous for the recesses 61 to be angularly distributed around the winding axis X in a constant manner. Typically, the angular distribution of the recesses 61 coincides with the angular distribution of the current collector tabs 50 along their aligned radial direction R. In other words, the angular distribution of the recesses 61 coincides with the angular distribution of the series connections 52. In this way, a uniformly distributed current collection around the winding axis X can be achieved.

[0075] Finally, the number of radially directed R is typically equal to the number of recesses 61. In this way, at least one recess 61 can be associated with each of the series 52 of current collector tabs 50 to collect all the current collected by the current collector tabs 50.

[0076] Various arrangements can be employed to facilitate the insertion of the series 52 into the recesses 61. Firstly, each recess 61 can have a width measured substantially perpendicular to the radial direction R, which is significantly greater than the maximum width of the current collector tab 50 aligned along the radial direction R, the maximum width being substantially perpendicular to the radial direction R. In this way, it can be ensured that the current collector tab 50 can easily pass through the channels of each recess 61.

[0077] Furthermore, a current collector tab 50 connected in series 52 can be welded together. This increases the cohesion between the current collector tabs 50, facilitating their insertion into the recess 61, while also improving the electrical connection between them and the mechanical strength of the welded assembly of current collector tabs 50. It should be understood that all current collector tabs 50 in a given series 52 are directly welded to each other. Typically, current collector tabs 50 in a given series 52 are only welded to each other to form an assembly consisting solely of the current collector tabs 50.

[0078] like Figure 3 As shown, advantageously, the current collector tab 50 passing through the at least one recess 61 is folded onto the welding surface s60s of the current collector 60 and makes close contact with the welding surface s60s. This allows for an increase in the contact area between the current collector tab 50 and the current collector 60, thereby improving the electrical connection between the current collector tab 50 and the current collector 60. To further improve this electrical connection, the current collector tab 50 folded onto the welding surface s60s can be welded to the welding surface s60s. Collaboratively, welding the current collector tab 50 to the current collector 60 maintains a good electrical connection while increasing the mechanical cohesion between the current collector 60 and the winding 30.

[0079] According to one variation, unit 1 may include at least one metal connecting member 56, which is welded to current collector tabs 50 aligned in the same radial direction R. In this way, the assembly of current collector tabs 50 welded together can be mechanically more robust.

[0080] Finally, unit 1 may also include a housing (not shown) that allows the addition of electrolyte to ensure charge exchange between the first electrode 10 and the second electrode 20. Typically, the housing comprises a cylindrical metal wall fixed to a metal bottom and a metal cap electrically insulated from the cylindrical wall and the metal bottom. The metal cap may be electrically connected to a first current collector, and the bottom or cylindrical wall may be connected to a second current collector. Thus, once the electrolyte has been introduced into the housing, current can circulate between electrodes 10 and 20 and can be collected by both the first and second current collectors. The cylindrical wall, bottom, and cap can then transmit this current to the outside of the housing, thereby providing current to the electric vehicle.

[0081] All of the above specifications allow for visualization of the welding of the current collector tab 50 during implementation. This also enables the use of more different types of welding and simplifies the manufacturing process.

[0082] The present invention also relates to a method for manufacturing unit 1 as described above, the manufacturing method comprising:

[0083] - The step of providing winding 30, wherein the collector tab 50 extends longitudinally along the winding axis X;

[0084] -Provide the steps for current collector 60;

[0085] - Insertion step, wherein the current collector tab 50 of the winding 30 is inserted into at least one recess 61 of the current collector 60 to pass through the current collector 60 on both sides and to ensure electrical connection between the first electrode 10 or the second electrode 20 and the current collector 60.

[0086] This makes it easier to manufacture cylindrical battery cells 1 by visualizing the current collector 60 during the welding of the current collector tab 50.

[0087] Optionally, the method also includes a welding step performed prior to the insertion step, during which all or part of the current collector tabs 50 aligned in the same radial direction R are welded together. This facilitates the implementation of the insertion step.

[0088] Furthermore, the method may also include a bending step following the insertion step, wherein the current collector tab 50 passing through at least one recess 61 is bent to make close contact with the welding surface s60s of the current collector 60. This ensures a good electrical connection between the tab and the current collector 60.

[0089] Finally, the method may also include a secondary welding step following the bending step, wherein the bent current collector tab 50 is welded to the welding surface s60s of the current collector 60. Therefore, the mechanical cohesion of the entire cylindrical battery cell 1 can be improved.

Claims

1. A battery cell (1) for an electric vehicle, the cell (1) comprising at least one stack comprising a continuous stack of sheets of: -First electrode (10); -First insulating partition (15); - The second electrode (20) has a polarity opposite to that of the first electrode (10); -Second insulating partition (25); The stack is wound around itself around a winding axis (X) to form a generally cylindrical winding (30). The unit (1) includes at least one current collector (60), which includes a conductive metal plate having a contact surface (s60c) facing the winding (30) and a welding surface (s60s) opposite to the contact surface (s60c). The current collector (60) includes at least one recess (61) that defines a channel in the metal plate opening on either side of the metal plate on the contact surface (s60c) and the welding surface (s60s). The recess (61) has an opening profile that includes an opening facing a central opening defined by the metal plate of the current collector (60). In unit (1), at least one electrode selected from the first electrode (10) and the second electrode (20) comprises a plurality of series (52), each series having a plurality of current collector tabs (50) configured to collect current from the at least one electrode, the series (52) being inserted into the at least one recess (61) to pass through the metal plate on either side, the series (52) contacting the metal plate to ensure electrical connection between the at least one electrode and the current collector (60).

2. The unit (1) according to claim 1, wherein, The current collector (60) includes two to eight recesses (61).

3. The unit (1) according to claim 2, wherein, The current collector (60) includes four recesses (61).

4. The unit (1) according to any one of claims 2 or 3, wherein, The recess (61) is angularly distributed around the winding axis (X) in a constant manner.

5. The unit (1) according to any one of claims 1 to 4, wherein, Given that the current collectors (50) in series (52) are aligned substantially along at least one radial direction (R) perpendicular to the winding axis (X), the number of which is equal to the number of the recesses (61).

6. The cylindrical battery cell (1) according to claim 5, wherein, Each recess (61) has a width that is substantially perpendicular to the radial direction (R), which is significantly greater than the maximum width of the current collector tab (50) aligned along the radial direction (R), which is substantially perpendicular to the radial direction (R).

7. The unit (1) according to any one of claims 5 or 6, wherein, The collector tabs (50) of the same series (52) are welded together.

8. The unit (1) according to any one of claims 1 to 7, wherein, The current collector tab (50) passing through the at least one recess (61) is folded onto the welding surface (s60s) of the current collector (60) and makes close contact with the welding surface (s60s).

9. The unit (1) according to claim 8, wherein, The current collector tab (50) folded on the welding surface (s60s) is welded to the welding surface (s60s).

10. A method for manufacturing the unit (1) according to any one of claims 1 to 6, the manufacturing method comprising: - The step of providing a winding (30), wherein the current collector tab (50) extends longitudinally along the winding axis (X); -Provide the steps for the current collector (60); - Insertion step, wherein the current collector tab (50) of the winding (30) is inserted into at least one recess (61) of the current collector (60) so as to pass through the current collector (60) on either side and ensure electrical connection between the first electrode (10) or the second electrode (20) and the current collector (60).

11. The method for manufacturing the unit (1) according to claim 7 according to claim 10, the method further comprising a welding step performed prior to the insertion step, during which all or part of the current collector tabs (50) aligned in the same radial direction (R) are welded together.

12. The method for manufacturing the unit (1) according to claim 11, further comprising a bending step performed after the insertion step, in which the current collector tab (50) passing through at least one recess (61) is bent to make close contact with the welding surface (s60s) of the current collector (60).

13. The method for manufacturing the unit (1) according to claim 12, the method further comprising a secondary welding step performed after the bending step, in which the bent current collector tab (50) is welded to the welding surface (s60s) of the current collector (60).

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