Cylindrical battery cell and method for manufacturing same

Abstract

The invention relates to an electric battery cell (1) comprising at least one successive stack of a sheet of a first electrode (10), of a first insulating separator (15), of a second electrode (20) and of 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 outline, in which cell (1) at least one electrode comprises a plurality of series (52) each comprising a plurality of current-collection 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 making contact with the metal plate so as to make an electrical connection between the at least one electrode and the current collector (60).

Description

[0001] DESCRIPTION

[0002] TITLE: Cylindrical battery cell and its manufacturing process

[0003] Technical field of the invention

[0004] The present invention relates to a cylindrical battery cell, and a method of manufacturing such a battery cell.

[0005] State of the art

[0006] In the field of secondary batteries, and in particular batteries for electric vehicles, it is known to manufacture so-called cylindrical battery cells. Generally, such battery cells comprise two electrodes: an anode and a cathode in the form of sheets. These electrodes are then wound around a winding mandrel to form a substantially cylindrical winding. Between the anode and the cathode, a porous insulating separator is arranged, configured to prevent the formation of 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 used to transport ions between the two electrodes.

[0007] Electrode sheets comprise an active portion coated with an active material and a metal portion not coated with active material. The metal portion, free of active material, can be cut to form current-collecting tabs. Thus, once wound, the winding comprises tabs electrically connected to the anode on one side, and tabs electrically connected to the cathode on the other side.

[0008] The tabs allow an electrical connection to be made between different areas of the same electrode to optimize current collection.

[0009] To collect all the current from each of the tabs, it is known to deposit and weld a current collector on said tabs.

[0010] The electrical connection of a current collector to the current collection tabs is achieved by positioning a contact face of said collector on the current collection tabs and then applying solder to a face opposite the contact face. Although this technique allows the cell current to be collected, it is the cause of defects, sometimes requiring the scrapping of said cells, and is therefore called for improvement.

[0011] During assembly, the current collector is placed on the tabs, the contact face then rests on said tabs causing them to bend. The bending is therefore carried out haphazardly and it is not possible to know with certainty the orientation and / or distribution of the tabs under the current collector. A pile of tabs may form in various localized locations, and consequently certain areas of the current collector may not be in contact with tabs. Current collection by the current collector then becomes inhomogeneous and the welds made above areas without tabs are ineffective if not useless, to the detriment of the overall performance of the cell.

[0012] Therefore, there is a need to find a reliable, practical and inexpensive method to electrically connect the tabs with the current collector.

[0013] Subject of the invention

[0014] The present invention aims to propose a solution which addresses all or part of the aforementioned problems, namely: proposing a battery cell in which the tabs are visually welded to the current collector; increasing the number of welding techniques which can be implemented during the welding step; reducing production costs; reducing the number of defective cells.

[0015] This aim can be achieved by implementing an electric battery cell for an electrically powered vehicle, said cell comprising at least one successive stack of a sheet: of a first electrode; of a first insulating separator; of a second electrode of polarity opposite to the first electrode; of a second insulating separator; the stack being wound on itself around a winding axis so as to form a substantially cylindrical winding, said cell comprising at least one current collector comprising an electrically conductive metal plate having a contact face facing the winding and a welding face opposite to said contact face, the current collector comprising at least one recess defining a passage in the metal plate opening on either side of the metal plate onto the contact face and onto the welding face, said recess having an open contour;cell in which at least one electrode chosen from the first electrode and the second electrode comprises several series each comprising a plurality of current collection tabs configured to collect an electric current from said at least one electrode, said series being inserted into said at least one recess so as to pass through the metal plate on either side, said series being in contact with the metal plate so as to ensure an electrical connection between said at least one electrode and the current collector.;

[0016] The arrangements described above allow the welding of the current collecting tabs to be visualized as it is implemented. This also allows the use of a greater number of different types of welding, and simplifies the manufacturing process.

[0017] The cell may further exhibit one or more of the following characteristics, taken alone or in combination.

[0018] According to one embodiment, the current collector comprises between two and eight offsets.

[0019] In this way, it is possible to adjust the number of detachments according to the distribution of the current collection tabs around the winding axis.

[0020] According to one embodiment, the current collector comprises four recesses.

[0021] Advantageously, the presence of four recesses allows for the best compromise between good current collection, guaranteed by a large number of recesses, and simplicity of manufacture.

[0022] According to one embodiment, the offsets are angularly distributed around the winding axis in a constant manner.

[0023] In this way, it is possible to achieve a uniformly distributed current collection around the winding axis.

[0024] According to one embodiment, the current collection tabs of a given series are substantially aligned in at least one radial direction, perpendicular to the winding axis, the number of radial directions being equal to the number of offsets. Generally, a series of current collection tabs comprises all the current collection tabs aligned in the same radial direction.

[0025] In this way, it is possible to match at least one notch to each of the series of current collection tabs so as to collect the entire current collected by the current collection tabs.

[0026] According to one embodiment, each step has a width measured substantially perpendicular to a radial direction, which is strictly greater than a greatest width of the current collection tabs aligned in this radial direction, said greatest width being measured substantially perpendicular to this radial direction.

[0027] In this way, it is possible to ensure easy passage of the current collection tabs through each recess. According to one embodiment, the current collection tabs of the same series are welded together. Generally, the current collection tabs of a given series are welded only together, to form an assembly consisting only of said current collection tabs.

[0028] In this way, it is possible to improve the cohesion between the current collection tabs, which makes it easier to insert them into the recesses, while improving the electrical connection between them, and the mechanical resistance of all the current collection tabs welded together.

[0029] According to one embodiment, the current collection tabs passing through said at least one recess are folded onto the welding face of the current collector and come into intimate contact with said welding face.

[0030] This increases the exchange surface area between the current collection tabs and the current collector, which improves the electrical connection between the current collection tabs and the current collector.

[0031] According to one embodiment, the current collecting tabs folded over the welding face are welded to said welding face.

[0032] Synergistically, soldering the current collection tabs to the current collector helps maintain a good electrical connection while improving the mechanical cohesion between the current collector and the winding.

[0033] The aim of the invention can also be achieved by implementing a method for manufacturing a cell as described above, the manufacturing method comprising: a step of providing a winding, in which the current collection tabs extend longitudinally along the winding axis; a step of providing a current collector; an insertion step in which the current collection tabs of the winding are inserted into the at least one recess of the current collector, so as to pass through the current collector on either side and ensure an electrical connection between the first electrode or the second electrode and the current collector.

[0034] This makes it easier to manufacture a cylindrical battery cell by visualizing the current collector when soldering the current collection tabs.

[0035] The manufacturing process may further have one or more of the following characteristics, taken alone or in combination.

[0036] According to one embodiment, the method further comprises a primary welding step implemented before the insertion step, during which all or part of the current collection tabs aligned in the same radial direction are welded together.

[0037] This makes it easier to implement the insertion step.

[0038] According to one embodiment, the method further comprises a folding step implemented after the insertion step, in which the current collecting tabs passing through the at least one recess are folded so as to come into intimate contact with the welding surface of the current collector.

[0039] This ensures a good electrical connection between the tabs and the current collector.

[0040] According to one embodiment, the method further comprises a secondary welding step performed after the bending step, in which the bent current collecting tabs are welded to the welding face of the current collector.

[0041] This makes it possible to improve the mechanical cohesion of the entire cylindrical battery cell.

[0042] Summary description of the drawings

[0043] Other aspects, aims, advantages and characteristics of the invention will appear better on reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and made with reference to the appended drawings in which:

[0044] Figure 1 is a schematic view of the constituent elements of the winding according to one embodiment of the invention.

[0045] Figure 2 is a schematic view of a battery cell according to one embodiment of the invention.

[0046] Figure 3 is a schematic view of the battery cell of Figure 2.

[0047] Figure 4 is a schematic view of a current collector for a battery cell according to a particular embodiment of the invention.

[0048] Detailed description

[0049] In the figures and in the remainder of the description, the same references represent identical or similar elements. In addition, the different elements are not shown to scale so as to enhance the clarity of the figures. Furthermore, the different embodiments and variants are not mutually exclusive and can be combined with each other.

[0050] As can be seen in Figures 1 to 3, the invention relates to an electric battery cell 1 for an electrically powered vehicle, said cell 1 comprising at least one successive stack of a sheet: of a first electrode 10; of a first insulating separator 15; of a second electrode 20 of polarity opposite to the first electrode 10; of a second insulating separator 25.

[0051] As can be seen in Figure 1, the first electrode 10 may in particular 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. In the case where the first electrode is an anode, the first metal sheet 11 may comprise copper. The layer of first active material 13 is generally coated over the entire length of the first metal sheet 11, with the exception of a peripheral strip devoid of active material coating.

[0052] In the same way, the second electrode 20 may comprise a second metal foil 21 in the form of a thin strip, on which a layer of a second active material 23 is deposited. In the case where the second electrode is a cathode, the second metal foil 21 may comprise aluminum. The layer of second active material 23 is generally coated over the entire length of the second metal foil 11, with the exception of a peripheral strip devoid of active material coating.

[0053] Between each of the electrodes 10, 20, a separator strip 15, 25 is arranged so that no electrical contact is possible between the first electrode 10 and the second electrode 20. It is also generally provided that the first electrode 10 and the second electrode 20 are offset along a winding axis denoted “X” so that the areas without active material coating are offset on either side of the separator strips 15, 25.

[0054] As schematically illustrated in Figure 1, the stack is wound on itself around the winding axis X so as to form a substantially cylindrical winding 30.

[0055] In the winding 30, at least one electrode selected from the first electrode 10 and the second electrode 20 comprises several series 52 each comprising a plurality of current collection tabs 50 configured to collect an electric current from said at least one electrode. Moreover, as illustrated in FIGS. 1 and 2, it is generally provided that the first electrode 10 and the second electrode 20 comprise series 52 of current collection tabs 50. The current collection tabs 50 are generally arranged on a peripheral edge 12, 22 of the metal support sheet 11, 21 devoid of active material. In this way, it is possible to recover all of the current from the current collection tabs 50 which are connected to the same electrode, and this, on the same side of the winding 30.The current collection tabs 50 of a given series 52 may be substantially aligned along at least one radial direction R, perpendicular to the winding axis X. By "aligned" is meant that the current collection tabs angularly overlap. Generally, a series 52 of current collection tabs 50 comprises all the current collection tabs 50 aligned along the same radial direction R.

[0056] Generally, each current collection tab 50 extends between a proximal end 51 secured to the winding 30 and a free distal end 53. In the case where the first electrode 10 and the second electrode 20 both comprise current collection tabs 50, it is advantageous for the current collection tabs 50 of the first electrode 10 to be arranged on a first side of the winding 30, and for the current collection tabs 50 of the second electrode 20 to be arranged on a second side of the winding 30 opposite the first side. In other words, the current collection tabs 50 of each electrode 10, 20 are turned in opposite directions. This makes it possible to avoid any risk of electrical connection between the two electrodes 10, 20.

[0057] As can be seen in Figures 2 to 4, the cell 1 comprises at least one current collector 60 comprising an electrically conductive metal plate having a contact face s60c facing the winding 30 and a welding face s60s opposite said contact face s60c. This metal plate may have a generally circular outline, or inscribed in a circle, so that the current collector 60 has a general disc shape. In general, and as illustrated in Figure 2, a current collector 60 may be arranged on each side of the winding 30. Thus, a first current collector 60 may collect the current from the current collection tabs 50 belonging to the first electrode 10, and a second current collector 60 may collect the current from the current collection tabs 50 belonging to the second electrode 20.In the description, reference is sometimes made to a current collector 60, but it is understood that the provisions which apply to this current collector 60 may apply to several current collectors 60.

[0058] The current collector 60 comprises at least one recess 61 defining a passage in the metal plate opening on either side of the metal plate onto the contact face s60c and onto the welding face s60s, said recess 61 having an open contour. A recess 61 is in the form of a notch or a notch locally constituting a removal or a withdrawal of material relative to the rest of the metal plate of the current collector 60. As can be seen in FIGS. 2 and 3, the open contour of the recess 61 comprises an opening facing the outside of the current collector 60. In other words, the recess 61 then opens towards the outside of the metal plate of the current collector 60, at its external peripheral edge.

[0059] Alternatively, and as shown in Figure 4, the open contour of the recess 61 comprises an opening facing a central opening delimited by the metal plate of the current collector 60. In other words, the recess 61 then opens towards the inside of the metal plate of the current collector 60, at the level of this central opening, at an internal peripheral edge itself delimiting this central opening.

[0060] These two variants each make it possible to reduce the amount of material used to manufacture the current collector 60, while still allowing electrical connection with the 52 series comprising the current collection tabs 50. It is thus possible to facilitate the welding of a current collector 60 with 52 series of current collection tabs 50, by limiting the amount of material used to manufacture the current collector 60.

[0061] As can be seen in Figures 2 and 3, the series 52 are inserted into said at least one recess 61 so as to pass through the metal plate on either side. The series 52 are then in contact with the metal plate so as to ensure an electrical connection between said at least one electrode and the current collector 60.

[0062] As can be seen in the figures, the current collector 60 can comprise between two and eight offsets 61. In this way, it is possible to adjust the number of offsets 61 according to the distribution of the series 52 around the winding axis X. More particularly, it can be provided that the current collector 60 comprises four offsets 61. Advantageously, the presence of four offsets 61 makes it possible to obtain the best compromise between good current collection, guaranteed by a large number of offsets 61, and simplicity of manufacture. Furthermore, and although this is not limiting, it may be advantageous to provide that the offsets 61 are angularly distributed around the winding axis X in a constant manner.Generally, the angular distribution of the recesses 61 coincides with an angular distribution of radial directions R along which the current collection tabs 50 are aligned. In other words, the angular distribution of the recesses 61 coincides with an angular distribution of the series 52. In this way, it is possible to achieve a uniformly distributed current collection around the winding axis X.

[0063] Finally, it is generally provided that the number of radial directions R is equal to the number of recesses 61. In this way, it is possible to match at least one recess 61 to each of the series 52 of current collection tabs 50 so as to collect all of the current collected by the current collection tabs 50.

[0064] Various arrangements can be made to facilitate the insertion of the series 42 into the recesses 61. First of all, it can be provided that each recess 61 has a width measured substantially perpendicular to a radial direction R, which is strictly greater than a greatest width of the current collection tabs 50 aligned in this radial direction R, said greatest width being measured substantially perpendicular to this radial direction R. In this way, it is possible to guarantee easy passage of the current collection tabs 50 through each recess 61.

[0065] Furthermore, it is also possible for the current collection tabs 50 of the same series 52 to be welded together. In this way, it is possible to improve the cohesion between the current collection tabs 50, which makes it easier to insert them into the recesses 61, while improving the electrical connection between them, and the mechanical strength of all the current collection tabs 50 welded together. It is understood that all the current collection tabs 50 of a given series 52 are welded directly together. Generally, the current collection tabs 50 of a given series 52 are welded only together, to form an assembly consisting only of said current collection tabs 50.

[0066] As illustrated in Figure 3, it is advantageous for the current collecting tabs 50 passing through said at least one recess 61 to be folded onto the welding face s60s of the current collector 60 and to come into intimate contact with said welding face s60s. This makes it possible to increase the exchange surface between the current collecting tabs 50 and the current collector 60, which makes it possible to improve the electrical connection between the current collecting tabs 50 and the current collector 60. In order to further improve this electrical connection, it is possible for the current collecting tabs 50 folded onto the welding face s60s to be welded to said welding face s60s. Synergistically, the welding of the current collecting tabs 50 with the current collector 60 makes it possible to maintain a good electrical connection while improving the mechanical cohesion between the current collector 60 and the winding 30.

[0067] According to a variant, the cell 1 may comprise at least one metal connection member 56, said at least one metal connection member 56 being welded to the current collection tabs 50 which are aligned in the same radial direction R. In this way, it is possible to make the set of current collection tabs 50 welded together more mechanically solid.

[0068] Finally, the cell 1 may also comprise a housing (not shown) allowing the addition of an electrolyte to ensure a charge exchange between the first electrode 10 and the second electrode 20. Generally, the housing is provided with a metallic cylindrical wall secured to a metallic bottom, and a metallic cover electrically insulated from the cylindrical wall and the metallic bottom. The metallic cover may be electrically connected to the first current collector, and the bottom or the cylindrical wall may be connected to the second current collector. Thus, once the electrolyte has been introduced into the housing, an electric current may flow between the electrodes 10, 20, and may be collected on the one hand by the first current collector, and on the other hand by the second current collector.The cylindrical wall, the bottom and the cover can then communicate this current to the outside of the housing, and thus provide an electric current to the electrically powered vehicle.

[0069] All of the arrangements previously described make it possible to visualize the welding of the current collection tabs 50 when it is implemented. This also makes it possible to use a greater number of different types of welding, and to simplify the manufacturing process.

[0070] The invention also relates to a method for manufacturing a cell 1 as described above, the manufacturing method comprising: a step of providing a winding 30, in which the current collection tabs 50 extend longitudinally along the winding axis X; a step of providing a current collector 60; an insertion step in which the current collection tabs 50 of the winding 30 are inserted into the at least one recess 61 of the current collector 60, so as to pass through the current collector 60 on either side and provide an electrical connection between the first electrode 10 or the second electrode 20 and the current collector 60.

[0071] This makes it easier to manufacture a cylindrical battery cell 1 by viewing the current collector 60 when welding the current collection tabs 50.

[0072] Optionally, the method further comprises a primary welding step implemented before the insertion step, during which all or part of the current collection tabs 50 aligned in the same radial direction R are welded together. This makes it easier to implement the insertion step.

[0073] Furthermore, the method may further comprise a folding step implemented after the insertion step, in which the current collecting tabs 50 passing through the at least one recess 61 are folded so as to come into intimate contact with the welding surface s60s of the current collector 60. This makes it possible to ensure a good electrical connection between the tabs and the current collector 60.

[0074] Finally, it may be provided that the method further comprises a secondary welding step implemented after the folding step, in which the folded current collecting tabs 50 are welded to the welding face s60s of the current collector 60. It is thus possible to improve the mechanical cohesion of the entire cylindrical battery cell 1.

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 electrode (10); - a first insulating separator (15); - a second electrode (20) of polarity opposite to the first electrode (10) - a second insulating separator (25); the stack being wound on itself around a winding axis (X) so as to form a substantially cylindrical winding (30), said cell (1) comprising at least one current collector (60) comprising an electrically conductive metal plate having a contact face (s60c) facing the winding (30) and a welding face (s60s) opposite said contact face (s60c), the current collector (60) comprising at least one recess (61) defining a passage in the metal plate opening on either side of the metal plate onto the contact face (s60c) and onto the welding face (s60s), said recess (61) having an open contour, said open contour comprising an opening facing a central opening delimited by the metal plate of the current collector (60);cell (1) in which at least one electrode chosen from the first electrode (10) and the second electrode (20) comprises several series (52) each comprising a plurality of current collection tabs (50) configured to collect an electric current from said at least one electrode, said series (52) being inserted into said at least one recess (61) so as to pass through the metal plate on either side, said series (52) being in contact with the metal plate so as to ensure an electrical connection between said at least one electrode and the current collector (60).; 2. Cell (1) according to claim 1, in which the current collector (60) comprises between two and eight recesses (61).

3. Cell (1) according to claim 2, in which the current collector (60) comprises four recesses (61).

4. Cell (1) according to any one of claims 2 or 3, in which the recesses (61) are angularly distributed around the winding axis (X) in a constant manner.

5. Cell (1) according to any one of claims 1 to 4, in which the current collection tabs (50) of a given series (52) are substantially aligned according to at least one of the following: minus one radial direction (R), perpendicular to the winding axis (X), the number of radial directions (R) being equal to the number of offsets (61).

6. Cylindrical battery cell (1) according to claim 5, in which each step (61) has a width measured substantially perpendicular to a radial direction (R), which is strictly greater than a greatest width of the current collection tabs (50) aligned in this radial direction (R), said greatest width being measured substantially perpendicular to this radial direction (R).

7. Cell (1) according to any one of claims 5 or 6, in which the current collection tabs (50) of the same series (52) are welded together.

8. Cell (1) according to any one of claims 1 to 7, in which the current collection tabs (50) passing through said at least one recess (61) are folded onto the welding face (s60s) of the current collector (60) and come into intimate contact with said welding face (s60s).

9. Cell (1) according to claim 8, wherein the current collecting tabs (50) folded onto the welding face (s60s) are welded to said welding face (s60s).

10. Method of manufacturing a cell (1) according to any one of claims 1 to 6, the manufacturing method comprising: - a step of providing a winding (30), in which the current collection tabs (50) extend longitudinally along the winding axis (X); - a step of providing a current collector (60); - an insertion step in which the current collection tabs (50) of the winding (30) are inserted into the at least one recess (61) of the current collector (60), so as to pass through the current collector (60) on either side and ensure an electrical connection between the first electrode (10) or the second electrode (20) and the current collector (60).

11. Manufacturing method according to claim 10 of a cell (1) according to claim 7, said method further comprising a primary welding step implemented before the insertion step, during which all or part of the current collection tabs (50) aligned in the same radial direction (R) are welded together.

12. Manufacturing method according to claim 11 of a cell (1) according to claim 8, said method further comprising a folding step implemented after the insertion step, wherein the current collecting tabs (50) passing through the at least a step (61) are bent so as to come into intimate contact with the welding surface (s60s) of the current collector (60).

13. A method of manufacturing according to claim 12 a cell (1) according to claim 9, said method further comprising a secondary welding step carried out after the bending step, in which the bent current collecting tabs (50) are welded to the welding face (s60s) of the current collector (60).

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