Process for manufacturing a cylindrical battery cell

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 an insulating first separator (15), of a second electrode (20) of opposite polarity to the first electrode (10), and of a second separator (25), the first electrode (10) and / or second electrode (20) comprising current-collecting tabs (50), the cell (1) comprising at least one current collector (60) equipped with at least one insertion slot (61), the current-collecting tabs (50) being inserted into the at least one insertion slot (61) on either side of the current collector (60), the current-collecting tabs (50) being capable of electrically connecting the first electrode (10) or second electrode (20) on the one hand and the at least one current collector (60) on the other hand. The invention further relates to a process for manufacturing such a cell (1).

Description

[0001] DESCRIPTION

[0002] TITLE: Manufacturing process of a cylindrical battery cell

[0003] Technical field of the invention

[0004] The present invention relates to a method of manufacturing a cylindrical 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; allowing the tabs to be held with the current collector before implementing a welding step; increasing the number of welding techniques which can be implemented during the welding step; reducing production costs; and / or reducing the number of defective cells.

[0015] This aim can be achieved by implementing a method for manufacturing an electric battery cell for an electrically powered vehicle, said cell comprising at least one successive stack of a sheet of a first electrode; a first insulating separator; a second electrode of opposite polarity to the first electrode; a second separator; said at least one stack being wound on itself around a winding axis so as to form a substantially cylindrical winding, the manufacturing method comprising: a step of providing the winding, in which the first electrode and / or the second electrode comprises current collection tabs configured to collect an electric current, and in which the current collection tabs extend longitudinally along the winding axis; a step of providing a current collector provided with at least one insertion slot;an insertion step in which the current collection tabs of the winding are inserted into the at least one insertion slot 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; and 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.;

[0016] The above-described arrangements make it possible to propose a manufacturing method in which it is possible to manufacture a cylindrical battery cell more simply by visualizing the current collector during the welding of the current collection tabs. Furthermore, the primary welding step makes it easier to implement the insertion step.

[0017] The manufacturing process may further have one or more of the following characteristics, taken alone or in combination.

[0018] According to one embodiment, the method further comprises a bending step implemented after the insertion step, in which the current collecting tabs passing through the at least one insertion slot are bent so as to come into intimate contact with the welding surface of the current collector.

[0019] This ensures a good electrical connection between the current collection tabs and the current collector.

[0020] 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.

[0021] This makes it possible to improve the mechanical cohesion of the entire cylindrical battery cell.

[0022] According to one embodiment, during the primary welding step, the current collection tabs aligned in the same radial direction are welded directly together so as to form an assembly consisting solely of said current collection tabs.

[0023] In this way, it is possible to carry out an insertion step from the current collection tabs only, which limits the number of steps in the manufacturing process, and helps to limit costs

[0024] According to one embodiment, during the primary welding step, the current collection tabs aligned in the same radial direction are welded together, and are not welded to a reinforcing tab.

[0025] In this way, it is possible to do without the use of a reinforcing tab, also called a "tab" in the dedicated Anglo-Saxon terminology. The manufacturing process is therefore carried out with fewer elements. In addition, the assembly formed by the current collection tabs welded together has a thinner thickness, which allows insertion into insertion slots more easily, which would not be possible or difficult using a reinforcing tab.

[0026] The aim of the invention can also be achieved by implementing a cylindrical electric battery cell for an electrically powered vehicle obtained directly by the manufacturing method described above.

[0027] According to one embodiment, the 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 separator;said at least one stack being wound on itself around a winding axis so as to form a substantially cylindrical winding, cell in which, in the winding, 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, said cell comprising at least one current collector provided with at least one insertion slot, said series being inserted into the at least one insertion slot on either side of the current collector, said current collection tabs being capable of electrically connecting the first electrode or the second electrode on the one hand and the at least one current collector on the other hand.;

[0028] The arrangements described above make it possible to visualize the welding of the current collecting tabs 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. The presence of insertion slots also makes it possible to hold the current collecting tabs together when they are inserted, which is particularly interesting when the current collecting tabs are very thin. Finally, this makes it possible to avoid the formation of a heterogeneous and non-uniform metal mass under the current collector. These metal masses make assembly more tedious and the electrical connection hazardous.

[0029] According to one embodiment, the current collector comprises between two and eight insertion slots.

[0030] In this way, it is possible to adjust the number of insertion slots depending on the distribution of the current collecting tabs around the winding axis. According to one embodiment, the current collector comprises four insertion slots.

[0031] Advantageously, the presence of four insertion slots makes it possible to obtain the best compromise between good current collection, guaranteed by a large number of insertion slots, and simplicity of manufacturing.

[0032] According to one embodiment, the insertion slots are angularly distributed around the winding axis in a constant manner.

[0033] In this way, it is possible to achieve a uniformly distributed current collection around the winding axis.

[0034] By "constant" we mean that an angular gap between two insertion slots is always equal. In other words, the angle separating two insertion slots is always the same.

[0035] 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 insertion slots.

[0036] In this way, it is possible to match an insertion slot to each of the series of current collection tabs so as to collect all of the current collected by the current collection tabs.

[0037] According to one embodiment, the current collection tabs of the same series are welded together.

[0038] In this way, it is possible to improve the cohesion between the current collection tabs, which makes it easier to insert them into the insertion slots, while improving the electrical connection between them, and the mechanical resistance of the set of current collection tabs welded together.

[0039] According to one embodiment, the current collector comprises a plate having a contact face facing the stack of electrodes and separators; and a welding face, opposite said contact face, each insertion slot opening onto the contact face on the one hand and onto the welding face on the other hand, the tabs passing through the insertion slots being folded onto said welding face and coming into intimate contact with said welding face.

[0040] 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.

[0041] According to one embodiment, the current collecting tabs folded over the welding face are welded to said welding face.

[0042] Synergistically, welding the current collection tabs to the current collector maintains a good electrical connection while improving the mechanical cohesion between the current collector, and the electrode winding and separator.

[0043] Summary description of the drawings

[0044] 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:

[0045] Figure 1 is a schematic view of the constituent elements of the winding according to one embodiment of the invention.

[0046] Figure 2 is a schematic view of a battery cell according to one embodiment of the invention.

[0047] Figure 3 is a schematic view of the battery cell of Figure 2.

[0048] Figure 4 is a schematic view of the battery cell of Figure 2.

[0049] Figure 5 is a schematic view of the battery cell of Figure 2.

[0050] Detailed description

[0051] 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.

[0052] As can be seen in Figures 1 to 5, the invention relates to an electric battery cell 1 for an electrically powered vehicle obtained directly according to the manufacturing method which will be described later. This cell 1 comprises 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 separator 25.

[0053] As can be seen in Figure 1, the first electrode 10 may in particular comprise a first metal foil 11 comprising a first active portion coated with a layer of a first active material 13. In the case where the first electrode is an anode, the first metal foil 11 may comprise copper. The layer of first active material 13 is generally coated over the entire length of the first metal foil 11 at the first active portion. The first electrode 10 also comprises a first metal portion devoid of first active material 13. Generally, the first metal portion is a peripheral strip of the first electrode which is devoid of coating of first active material 13.

[0054] In the same way, the second electrode 20 may comprise a second metal foil 21 comprising a second active portion coated with a layer of a second active material 23. 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 21 at the second active portion. The second electrode 20 also comprises a second metal portion devoid of second active material 23. Generally, the second metal portion is a peripheral strip of the second electrode 20 which is devoid of coating of second active material 23.

[0055] 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 first active portion and the second active portion are offset from each other on either side of the separator strips 15, 25.

[0056] Said at least one stack is wound on itself around the winding axis X so as to form a substantially cylindrical winding 30.

[0057] 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.

[0058] Moreover, as illustrated in FIG. 1, 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 10, 20, and this, on the same side of the winding 30.

[0059] Advantageously, the current collection tabs 50 of a given series 52 can be substantially aligned in at least one radial direction R, perpendicular to the winding axis X. The current collection tabs 50 aligned in the same radial direction R are welded together. This generally means that the current collection tabs 50 aligned in the same radial direction R are welded directly together so as to form an assembly consisting solely of said current collection tabs 50. The radial current collection tabs 50 are therefore welded together, and are not welded to a reinforcing tab. In this way, it is possible to avoid the use of a reinforcing tab, also called a "tab" according to the dedicated Anglo-Saxon terminology. Thus, the assembly formed by the current collection tabs 50 welded together has a thinner thickness.In this way, it is possible to improve the cohesion between the current collection tabs 50, which makes it easier to insert them into insertion slots 61 which will be described later, while improving the electrical connection between them, and the mechanical strength of all the current collection tabs 50 welded together. By "aligned" is meant that the current collection tabs 50 overlap angularly.

[0060] Referring now to Figures 2 to 5, the cell 1 further comprises at least one current collector 60 provided with at least one insertion slot 61. By “slot” is meant an opening made through a thickness of the current collector, which has a closed contour. This closed contour comprises a larger dimension which is the length of the slot, and a smaller dimension which is the width of the slot. It is therefore clearly understood that the insertion slot 61 corresponds to an absence of material in the current collector 60.

[0061] Although Figures 2 to 5 show only one current collector 60, it is understood that another current collector 60 can be arranged on the side opposite the winding 30. Thus, a first current collector 60 can collect the current from the current collection tabs 50 belonging to the first electrode 10, and a second current collector can collect the current from the current collection tabs belonging to the second electrode 20. In the description, reference is sometimes made to a current collector 60, but it is understood that the arrangements which apply to this current collector 60 can apply to several current collectors.

[0062] Generally, the current collector 60 may comprise between two and eight insertion slots 61. In this way, it is possible to adjust the number of insertion slots 61 according to the distribution of the current collection tabs 50 around the winding axis X. More particularly and as illustrated in FIGS. 2 to 5, the current collector 60 comprises four insertion slots 61. Advantageously, the presence of four insertion slots 61 makes it possible to obtain the best compromise between good current collection, guaranteed by a large number of insertion slots 61, and simplicity of manufacture.

[0063] In order to achieve uniformly distributed current collection around the winding axis X, it is possible to provide that the insertion slots 61 are angularly distributed around the winding axis X in a constant manner. By "constant" is meant that an angular difference between two insertion slots 61 is always equal. In other words, the angle separating two insertion slots 61 is always the same.

[0064] As can be seen in Figures 3 to 5, the series 52 are inserted into the at least one insertion slot 61 on either side of the current collector 60. The series are then in intimate contact with the current collector 60, and the current collection tabs 50 are then able to electrically connect the first electrode 10 or the second electrode 20 on the one hand and the at least one current collector 60 on the other hand.

[0065] As seen in the figures, the number of radial directions R may be equal to the number of insertion slots 61. In this way, it is possible to match one insertion slot 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.

[0066] The current collector 60 generally comprises a plate having a contact face s60c facing the stack of electrodes and separators; and a welding face s60s, opposite said contact face s60c. This plate may have a generally circular outline, so that the current collector 60 has a general disc shape.

[0067] Each insertion slot 61 opens onto the contact face s60c on the one hand and onto the welding face s60s on the other hand. The current collecting tabs 50 passing through the insertion slots 61 can then be folded onto said welding face s60s and coming into intimate contact with said welding face s60s. Such an arrangement is shown in Figures 4 and 5. 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. Furthermore, it is also possible for the current collecting tabs 50 of the same series 52 to be welded together. Furthermore, it may be advantageous to provide that the series 52 of current collecting tabs 50 are folded over the welding face s60s and welded to said welding face s60s.Thus, and in a synergistic manner, the welding of the current collection 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 of the electrodes and the separator.

[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] The arrangements described above 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. The presence of insertion slots 61 also makes it possible to hold the current collection tabs 50 together when they are inserted, which is particularly advantageous when the current collection tabs 50 have a very thin thickness. Finally, this makes it possible to avoid the formation of a heterogeneous and non-uniform metal mass under the current collector 60. These metal masses make assembly more tedious and the electrical connection hazardous.

[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 insertion slot 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.

[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] 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] Advantageously, during the primary welding step, the current collection tabs 50 aligned in the same radial direction R are welded directly together so as to form an assembly consisting solely of said current collection tabs. In this way, it is possible to carry out the insertion step using only the current collection tabs 50, which limits the number of steps in the manufacturing process, and makes it possible to limit costs. Furthermore, during the primary welding step, the current collection tabs 50 aligned in the same radial direction R are welded together, and are not welded to a reinforcing tab. In this way, it is possible to avoid the use of a reinforcing tab, also called a "tab" according to the dedicated Anglo-Saxon terminology. The manufacturing process is therefore carried out with fewer elements.Furthermore, the assembly formed by the current collection tabs 50 welded together has a thinner thickness, which allows insertion into insertion slots 61 more easily, which would not be possible or difficult using a reinforcing tab.

[0074] Furthermore, the method may comprise a folding step illustrated in FIGS. 4 and 5, and implemented after the insertion step. During this step, the current collecting tabs 50 passing through the at least one insertion slot 61 are folded so as to come into intimate contact with the welding surface s60s of the current collector 60. This ensures a good electrical connection between the current collecting tabs 50 and the current collector 50.

[0075] Following this folding step, the method may comprise a secondary welding 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. Method for manufacturing 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); a first insulating separator (15); a second electrode (20) of opposite polarity to the first electrode (10); a second separator (25); said at least one stack being wound on itself around a winding axis (X) so as to form a substantially cylindrical winding (30), the manufacturing method comprising: - a step of providing the winding (30), in which the first electrode (10) and / or the second electrode (20) comprises current collection tabs (50) configured to collect an electric current, and in which the current collection tabs (50) extend longitudinally along the winding axis (X); - a step of providing a current collector (60) provided with at least one insertion slot (61); - an insertion step in which the current collecting tabs (50) of the winding (30) are inserted into the at least one insertion slot (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); and - 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.

2. Manufacturing method according to claim 1 wherein the current collector (60) comprises a plate having a contact face (s60c) facing the stack of electrodes and separators; and a welding face (s60s), opposite said contact face (s60c), and where each insertion slot (61) opens onto the contact face (s60c) on the one hand and onto the welding face (s60s) on the other hand, said method further comprising a folding step implemented after the insertion step, in which the current collection tabs (50) passing through the at least one insertion slot (61) are folded so as to come into intimate contact with the welding surface (s60s) of the current collector (60).

3. A manufacturing method according to claim 2 further comprising a secondary welding step carried out after the bending step, wherein the bent current collecting tabs (50) are welded to the welding face of the current collector (60).

4. Manufacturing method according to any one of claims 1 to 3, wherein during the primary welding step, the current collection tabs (50) aligned in the same radial direction (R) are welded directly together so as to form an assembly consisting solely of said current collection tabs (50).

5. Manufacturing method according to any one of claims 1 to 4, wherein during the primary welding step, the current collection tabs (50) aligned in the same radial direction (R) are welded together, and are not welded to a reinforcing tab.

6. Cylindrical electric battery cell (1) for an electrically powered vehicle obtained directly by the manufacturing method according to any one of claims 1 to 5.

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