Cylindrical battery cell and its manufacturing process

Abstract

The invention relates to an electric battery cell (1) comprising a winding (30) of a first electrode (10), a first separator (15), a second electrode (20), and a second separator (25), around a winding axis (X), wherein, in the winding (30), the first electrode (10) and / or the second electrode (20) comprises several series (52), each having a plurality of current-collecting tabs (50) configured to collect an electric current, the current-collecting tabs (50) of a given series (52) being aligned along a radial direction (R) substantially perpendicular to the winding axis (X), the current-collecting tabs (50) of a given series (52) being welded together, and said welded current-collecting tabs (50) protrude from the winding (30) along an extension direction defined parallel to the axis winding (X).The invention also relates to a method for manufacturing such a cell (1). Figure 1.

Description

Title of the invention: Cylindrical battery cell and its manufacturing process. Technical field of the invention

[0001] The present invention relates to a cylindrical battery cell, and a method for manufacturing such a battery cell. State of the art

[0002] In the field of secondary batteries, and particularly 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 foils. These electrodes are then wound around a winding mandrel to form a main winding that constitutes the cylindrical battery cell. Between the anode and the cathode, a separator is positioned to prevent the formation of a short circuit between the two electrodes. The main winding is then inserted into a casing that serves, in particular, to protect the main winding and / or to allow the insertion of an electrolyte for transporting ions between the two electrodes.

[0003] These battery cells have the advantage of being easily manufactured by a simple winding of the electrode and separator strips, which makes it possible to increase production rates, and thus reduce costs.

[0004] In order to collect the current generated by the operating battery cell, it is known in the prior art to provide that the electrode strips are formed by the deposition of an active material onto an electrically conductive strip. A portion of this electrically conductive strip is devoid of active material and can be cut along one edge to form current-collecting tabs. Thus, once wound, the main winding comprises, on one side, tabs electrically connected to the anode, and on the other side, tabs electrically connected to the cathode.

[0005] The tabs allow an electrical connection to be made between different areas of the same electrode, so that the polarity of the whole of an electrode strip can be captured from outside the battery cell.

[0006] To collect all the current from each of the tabs, it is known to place a current collector on said tabs and weld the current collector to the tabs. Thus, there is a current collector for each electrode. The first current collector can be electrically connected to the housing cover, and the second current collector can The casing is electrically connected, with the casing cover and the casing electrically insulated from each other. As a result, a current can flow through the casing, for example via its cylindrical wall, to supply electrical power to the vehicle.

[0007] The electrical connection of a current collector is generally made by blindly applying the current collector to the tabs and welding it to a face opposite to the one in contact with the tabs. Although this method is satisfactory in that it allows current to be drawn from the cylindrical cell without requiring a connecting tab, it can generate defects or difficulties during its implementation.

[0008] Indeed, when the current collector is applied to the tabs, it is impossible to know the orientation of the tabs between the current collector and the main winding. It is possible that several tabs may be grouped in the same place, and that some areas of the current collector may not be in contact with any tab. The current collection on the current collector then becomes inhomogeneous, which can degrade current collection. More problematically, it is possible that a tab may be folded inwards towards the main winding and make electrical contact with the electrode of opposite polarity, which can lead to the destruction of the battery cell or prevent its operation.Finally, performing a welding step on a face opposite to the one where the tabs are located is a blind operation, the quality of which can only be verified during a test stage at the end of battery manufacturing. Furthermore, this step requires the use of dedicated welding methods, which can sometimes be expensive or difficult to implement.

[0009] There is therefore a need to find a reliable, practical and inexpensive method for electrically connecting the tabs with the current collector.

[0010] Object and invention

[0011] The present invention aims to provide a solution that addresses all or part of the aforementioned problems, namely: - propose a battery cell in which the tabs can be visually welded to the current collector; - increase the number of welding techniques that can be implemented during the welding stage; - reduce production costs; - decrease the number of defective cells.

[0012] This goal can be achieved through the implementation of an electric battery cell for an electric propulsion vehicle, said cell comprising at least one successive stack of a sheet: - of a first electrode; - of a first insulating separator; - a second electrode with the opposite polarity to the first electrode; - a second insulating separator;

[0013] said at least one stack being wound around itself around a winding axis so as to form a substantially cylindrical winding;

[0014] cell in which, in the winding, the first electrode and / or the second electrode comprises several series each having a plurality of current-collecting tabs configured to collect an electric current, the current-collecting tabs of a given series being aligned in a radial direction substantially perpendicular to the winding axis from substantially the winding axis towards a periphery of the winding, each current-collecting tab extending between a proximal end fixed to the winding and a free distal end;

[0015] the current collection tabs of a given series being welded together and said welded current collection tabs protrude from the winding in a defined extension direction parallel to the winding axis.

[0016] The arrangements described above make it possible to propose a cylindrical battery cell in which the current collection tabs are grouped together before the welding operation with the current collector, which facilitates the welding operation, and limits the risk of bending the current collection tabs in undesired directions.

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

[0018] According to one embodiment, the first electrode and the second electrode each comprise a metallic support sheet and a layer of active material deposited on said metallic support sheet, the current-collecting tabs being arranged on a peripheral edge of the metallic support sheet devoid of active material.

[0019] In this way, it is possible to recover all the current from the current collection tabs which are connected to the same electrode, and on the same side of the winding.

[0020] According to one embodiment, each current collection tab is spaced from the current collection tab preceding it along the peripheral edge by a variable interval which increases between an inner end of the sheet arranged radially closest to the winding axis, and an outer end of the sheet arranged radially furthest from the winding axis.

[0021] The arrangements described above allow the current collection tabs of the same series to be automatically aligned along the radial direction, When the electrodes are wound to form the winding, it is then possible to distribute series of current-collecting tabs according to a specific arrangement, which is considered more efficient for current collection.

[0022] According to one embodiment, the number of series is between two and eight.

[0023] In this way, it is possible to adjust the number of series according to the distribution of current collection tabs around the winding axis.

[0024] According to one embodiment, the number of series is equal to four.

[0025] Advantageously, the presence of four series makes it possible to obtain the best compromise between good current collection, guaranteed by a large number of series, and simplicity of manufacture.

[0026] According to one embodiment, the series are angularly distributed around the winding axis in a constant manner.

[0027] In this way, it is possible to achieve a current collection uniformly distributed around the winding axis

[0028] According to one embodiment, the cell comprises at least one metallic connecting element, said at least one metallic connecting element being welded to the current collection tabs which are aligned along the same radial direction.

[0029] In this way, it is possible to make the entire set of current collection tabs welded together more mechanically robust.

[0030] According to one embodiment, the current collection tabs of the same series have a substantially constant width, said width being measured perpendicular to said radial direction.

[0031] Thus, the exchange surface between the different current collection tabs welded together is maximized, which improves current extraction.

[0032] According to one embodiment, the cell further comprises a current collector having at least one opening, the current collection tabs being inserted into at least one opening on either side of the current collector, said current collection tabs being able to electrically connect the first electrode or the second electrode on the one hand and at least one current collector on the other hand.

[0033] This allows for easy insertion of the current collection tabs into the current collector, particularly for visualizing the weld of the current collection tabs during implementation. It also allows the use of a greater number of different weld types and simplifies the manufacturing process.

[0034] The object of the invention can also be achieved through the implementation of a manufacturing process for a cell as described above, the manufacturing process comprising: - a step of making a winding available; - a welding step during which the current collection tabs aligned along the same radial direction are welded together, and said current collection tabs welded together protrude from the winding along a defined extension direction parallel to the winding axis.

[0035] The arrangements described above make it possible to manufacture a cylindrical cell, facilitating the step of welding the tabs with a current collector.

[0036] Brief description of the drawings

[0037] Other aspects, objectives, advantages and features of the invention will become more apparent upon reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and made with reference to the accompanying drawings in which:

[0038] [Fig-1] Fig. 1 is a schematic view of certain steps in the process of manufacturing a battery cell according to an embodiment of the invention.

[0039] [Fig.2] Fig.2 is a schematic view of a battery cell according to a mode of realization of the invention.

[0040] [Fig.3] The [Fig.3] is a schematic view of the battery cell of the [Fig.2].

[0041] [Fig.4] Fig.4 is a schematic view of a battery cell according to another method of embodiment of the invention. Detailed description

[0042] In the figures and throughout the description, the same reference numerals represent identical or similar elements. Furthermore, the various elements are not drawn to scale in order to enhance the clarity of the figures. Moreover, the different embodiments and variants are not mutually exclusive and may be combined.

[0043] As can be seen in Figures 1 to 4, the invention relates to an electric battery cell 1 for an electric vehicle. This cell 1 comprises at least one successive stack of a sheet: - of a first electrode 10; - of a first insulating separator 15; - a second electrode 20 of opposite polarity to the first electrode 10; - of a second insulating separator 25.

[0044] As can be seen in [Fig. 1], the first electrode 10 and the second electrode 20 can each comprise a metallic support sheet 11, 21 and a layer of active material 13, 23 deposited on said metallic support sheet 11, 21.

[0045] The first electrode 10 may include, in particular, a first metal foil 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 foil 11 may include copper. The layer of first active material 13 is generally coated along the entire length of the first metal foil 11, with the exception of a peripheral strip, disposed on a first peripheral edge 12 of the first metal support foil 11, and uncoated with active material.

[0046] Similarly, 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 along the entire length of the second metal foil 11, with the exception of a peripheral strip disposed on a second peripheral edge 22 of the second metal support foil 21, and which is uncoated with active material.

[0047] 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 marked "X" so that the peripheral strips without active material coating are offset on either side of the separator strips 15, 25.

[0048] At least one stack is wound around the winding axis X so as to form a substantially cylindrical winding 30.

[0049] In the winding 30, the first electrode 10 and / or the second electrode 20 comprise several series 52, each having a plurality of current-collecting tabs 50 configured to collect an electric current. The current-collecting tabs 50 are generally arranged on the peripheral edge 12, 22 of the metallic support sheet 11, 21, which is free of active material. In this way, it is possible to collect all the current from the current-collecting tabs 50 that are connected to the same electrode on the same side of the winding 30.

[0050] The current collection tabs 50 of a given series 52 are aligned along a radial direction R substantially perpendicular to the winding axis X from substantially the winding axis X towards a periphery of the winding 30. By "aligned" means that the current collection tabs 50 overlap angularly.

[0051] For example, each current collection tab 50 can be spaced from the current collection tab 50 preceding it along the peripheral edge 12, 22 by a variable interval denoted "NG" which increases between an inner end of sheet arranged radially closest to the winding axis X, and an outer end of sheet arranged radially furthest from the winding axis X.Such a variable interval NG can be defined by the following formula: NG = ff + n*l, where g corresponds to the interval separating the current-collecting tab 50 closest to a winding mandrel used to wind the winding 30 and the current-collecting tab 50 directly following it, where n corresponds to the current-collecting tab 50 located in the nth position relative to the current-collecting tab 50 closest to a winding mandrel, and where l corresponds to the length of increase of the winding spiral as a function of the thickness of the stack of electrodes 10, 20, and separator strips 15, 25. The arrangements described above allow the current-collecting tabs 50 of the same series 52 to be automatically aligned along the radial direction R, when the electrodes 10, 20 are wound to form the winding 30.It is then possible to distribute series 52 of current collection tabs 50 according to a determined arrangement, which is more efficient for achieving current collection.

[0052] Although not limiting, it may be advantageous to provide that the series 52 are angularly distributed around the winding axis X in a constant manner. In this way, it is possible to achieve a current collection uniformly distributed around the winding axis X

[0053] As can be seen in the figures, the number of series 52 is between two and eight. In this way, it is possible to adjust the number of series 52 according to the distribution of the current-collecting tabs 50 around the winding axis X. More specifically, it can be provided that the number of series 52 is equal to four. Advantageously, the presence of four series 52 makes it possible to obtain the best compromise between good current collection, guaranteed by a large number of series 52, and simplicity of manufacture.

[0054] The current collection tabs 50 of the same series 52 can have a substantially constant width, said width being measured perpendicular to said radial direction R. Thus, the exchange surface between the different current collection tabs 50 welded together is maximized, which improves current extraction.

[0055] Each current collection tab 50 extends between a proximal end 51 attached to the winding 30 and a free distal end 53. The current-collecting tabs 50 of a given series 52 are welded together, and said welded current-collecting tabs 50 protrude from the winding 30 in a defined extension direction parallel to the winding axis X. It is therefore well understood that the distal ends 53 are turned on the opposite side to the winding 30. In the case where the first electrode 10 and the second electrode 20 both include current-collecting tabs 50, it is advantageous that the current-collecting tabs 50 of the first electrode 10 protrude from the winding 30 on a first side of the winding 30, and that the current-collecting tabs 50 of the second electrode 20 protrude from the winding 30 on a second side of the winding 30 opposite to the first side.In other words, the current-collecting tabs 50 of each electrode are turned in opposite directions. This eliminates any risk of electrical connection between the two electrodes 10, 20.

[0056] As can be seen in Figures 2 to 4, the cell 1 may further include a current collector 60 having at least one opening 61. In this case, the current collection tabs 50 may be inserted into at least one opening 61 on either side of the current collector 60. 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 contour, so that the current collector 60 has a general disc shape. Each opening 61 may lead to the contact face s60c on one side and to the welding face s60s on the other.

[0057] Although not limiting, such an opening 61 can take the form of an insertion slot, as illustrated in Figures 2 and 3. The term "slot" refers to an opening 61 formed through a thickness of the current collector 60, 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 an insertion slot corresponds to an absence of material in the current collector 60.

[0058] Alternatively, and as shown in [Fig. 4], the opening 61 may take the form of at least one recess defining a passage in the current collector 60 and opening on either side of the current collector 60 onto the contact face s60c and onto the weld face s60s, said recess having an open contour. In the same way as for the slots, each recess may have a width measured substantially perpendicular to a radial direction R, which is strictly greater than a greater width of the current collection tabs 50 aligned along this radial direction R, said greater width being measured substantially perpendicular to this radial direction R.

[0059] Although Figures 2 and 3 show only one current collector 60, it is understood that another current collector 60 may be arranged on the opposite side of the winding 30, in the same manner as in [Fig. 4]. Thus, a first current collector 60 may collect the current from the first electrode 10 via the current-collecting tabs 50, and a second current collector 60 may collect the current from the second electrode 20 via other current-collecting tabs 50. In the description, reference is sometimes made to a single current collector 60, but it is understood that the arrangements applicable to this current collector 60 may apply to several current collectors 60.

[0060] Generally, the number of openings 61 in the current collector 60 is greater than or equal to the number of series 52. Thus, it is possible to recover the current from the set of series 52, by electrically connecting them to the current collector 60 on the same side.

[0061] The current-collecting tabs 50 are then able to electrically connect the first electrode 10 or the second electrode 20 on the one hand and at least one current collector 60 on the other. This allows for easy insertion of the current-collecting tabs 50 into the current collector 60, in particular to visualize the weld of the current-collecting tabs 50 when it is applied. This also allows the use of a greater number of different weld types and simplifies the manufacturing process.

[0062] According to an unrepresented variant, the cell 1 may include at least one metallic connecting member 56, said at least one metallic connecting member 56 being welded to the current collection tabs 50 which are aligned along the same radial direction R. In this way, it is possible to make the entire set of current collection tabs 50 welded together more mechanically strong.

[0063] Finally, cell 1 may also include a housing (not shown) allowing the addition of an electrolyte to ensure charge exchange between the first electrode 10 and the second electrode 20. Generally, the housing has a cylindrical metal wall attached to a metal base, and a metal lid electrically insulated from the cylindrical wall and the metal base. The metal lid can be electrically connected to the first current collector, and the base or the cylindrical wall can be connected to the second current collector. Thus, once the electrolyte is introduced into the housing, a current Electric current can flow between electrodes 10 and 20 and can be collected by the first current collector and the second current collector. The cylindrical wall, base, and lid can then transmit this current outside the housing, thus supplying electricity to the electric vehicle.

[0064] All the arrangements described above make it possible to propose a cylindrical battery cell 1 in which the current collection tabs 50 are grouped together before the welding operation with the current collector 60, which facilitates the welding operation, and limits the risk of bending the current collection tabs 50 in undesired directions.

[0065] The invention also relates to a method for manufacturing a cell 1 as described above, the manufacturing method comprising: - a step of making available a 30 winding; - a welding step during which the current collection tabs 50 aligned along the same radial direction R are welded together, and said current collection tabs 50 welded together protrude from the winding 30 along an extension direction defined parallel to the winding axis X.

[0066] The arrangements described above make it possible to manufacture a cylindrical cell 1, facilitating the step of welding the tabs with a current collector 60.

[0067] Optionally, the step of providing a winding 30 may include: - a cutting step in which the first electrode 10, and the second electrode 20 are each cut at the peripheral strip so as to form the current collection tabs 50, the cutting step being implemented so that the formation of each current collection tab 50 along the peripheral edge 12, 22 is distant from the tab preceding it by the variable interval NG; - a step of supplying separators 15, 25; - a winding stage, in which the first electrode 10, the first separator 15, the second electrode 20, and the second separator 25 are superimposed in that order, and wound around the winding axis X, the separators 15, 25 electrically insulating the first electrode 1 and the second electrode 20 from each other, the winding step allowing the formation of the winding 30.

Claims

1. Demands Electric battery cell (1) for an electric propulsion vehicle, said cell (1) comprising at least one successive stack of a sheet: • of a first electrode (10); • of a first insulating separator (15); • a second electrode (20) of opposite polarity to the first electrode (10); • of a second insulating separator (25); said at least one stack being wound around itself around a winding axis (X) so as to form a substantially cylindrical winding (30); cell (1) in which, in the winding (30), the first electrode (10) and / or the second electrode (20) comprises several series (52) each having a plurality of current-collecting tabs (50) configured to collect an electric current, the current-collecting tabs (50) of a given series (52) being aligned in a radial direction (R) substantially perpendicular to the winding axis (X) from substantially the winding axis (X) towards a periphery of the winding (30), each current-collecting tab (50) extending between a proximal end (51) fixed to the winding (30) and a free distal end (53); the current collection tabs (50) of a given series (52) being welded together and said welded current collection tabs (50) protrude from the winding (30) in an extension direction defined parallel to the winding axis (X); the electric battery cell (1) being characterized in that it further comprises a current collector (60) having at least one opening (61), the current collection tabs (50) being inserted into at least one opening (61) on either side of the current collector (60), said current collection tabs (50) being able to electrically connect the first electrode (10) or the second electrode (20) on the one hand and at least one current collector (60) on the other hand.

2. Cell (1) according to claim 1, wherein the first electrode (10) and the second electrode (20) each comprise a metallic support sheet (11, 21) and a layer of active material (13, 23) deposited on said metallic support sheet (11, 21), the current-collecting tabs (50) being arranged on a peripheral edge (12, 22) of the metallic support sheet (11, 21) devoid of active material.

3. Cell (1) according to claim 2, wherein each current collection tab (50) is spaced from the current collection tab (50) preceding it along the peripheral edge (12, 22) by a variable interval (NG) which increases between an inner end of sheet arranged radially closest to the winding axis (X), and an outer end of sheet arranged radially furthest from the winding axis (X).

4. Cell (1) according to any one of claims 1 to 3, wherein the number of series (52) is between two and eight.

5. Cell (1) according to claim 4, wherein the number of series (52) is equal to four.

6. Cell (1) according to any one of claims 1 to 5, wherein the series (52) are angularly distributed around the winding axis (X) in a constant manner.

7. Cell (1) according to any one of claims 1 to 6, comprising at least one metallic connecting member (56), said at least one metallic connecting member (56) being welded to the current collection tabs (50) which are aligned along the same radial direction (R).

8. Cell (1) according to any one of claims 1 to 7, wherein the current collection tabs (50) of the same series (52) have a substantially constant width, said width being measured perpendicular to said radial direction (R).

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