Cylindrical battery cell and process for manufacturing same

Abstract

The invention relates to an electric battery cell (1) comprising a winding (30) of a first electrode (10), of a first separator (15), of a second electrode (20), and of a second separator (25), about a winding axis (X), wherein, in the winding (30), the first electrode (10) and / or the second electrode (20) comprises a plurality of series (52) each comprising 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), the current-collecting tabs (50) of a given series (52) being welded together and the welded current-collecting tabs (50) protruding from the winding (30) in a direction of extension defined parallel to the winding axis (X). The invention also relates to a process for manufacturing such a cell (1).

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 main winding forming the cylindrical battery cell. Between the anode and the cathode, a separator is arranged configured to prevent the formation of a short circuit between the two electrodes. The main winding is then inserted into a casing serving in particular to protect the main winding, and / or to allow the insertion of an electrolyte used to transport ions between the two electrodes.

[0007] These battery cells have the advantage of being easily manufactured by simply winding the electrode and separator strips, which allows for increased production rates and thus reduced costs.

[0008] In order to collect the current generated by the battery cell in operation, it is known from the prior art to provide that the electrode strips are formed by the deposition of an active material on an electrically conductive strip. A portion of this electrically conductive strip is devoid of active material, and can be cut on one of the edges to form current collection 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.

[0009] The tabs allow an electrical connection to be made between different areas of the same electrode, so that the polarity of an entire electrode strip can be detected from outside the battery cell.

[0010] To collect all the current from each of the tabs, it is known to deposit a current collector on said tabs, and to weld the current collector with the tabs. Thus, there is for each of the electrodes, a current collector. The first current collector can be electrically connected to the cover of the housing, and the second current collector can be electrically connected to the housing, the cover of the housing and the housing being electrically insulated from each other. As a result, a current can pass through the housing, for example via its cylindrical wall, to supply electrical energy to the vehicle.

[0011] The electrical connection of a current collector is generally made by blindly applying the current collector to the tabs, and welding on a face opposite to that in contact with the tabs. Although this operation is satisfactory in that it allows current to be extracted from the cylindrical cell without requiring a connection tab, it can generate defects or difficulties in its realization.

[0012] Indeed, when applying the current collector to the tabs, it is not possible to know what the orientation of the tabs will be between the current collector and the main winding. It is indeed possible that several tabs are grouped in the same place, and that certain areas of the current collector are in contact with no tab. The current collection on the current collector then becomes inhomogeneous, which can degrade the current collection. More problematically, it is possible that a tab is folded towards the inside of the main winding and comes into 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 side opposite to that where the tabs are arranged is a blind operation, the quality of which can only be verified during a test step at the end of battery manufacturing. Furthermore, carrying out this step requires the use of dedicated welding methods, which can sometimes be expensive or difficult to implement.

[0013] Therefore, there is a need to find a reliable, practical and inexpensive method to electrically connect the tabs with the current collector.

[0014] Subject of the invention

[0015] 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 can be 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.

[0016] 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; 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, the first electrode and / or the second electrode comprises several series each comprising a plurality of current collection tabs configured to collect an electric current, the current collection 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 collection tab extending between a proximal end secured to the winding and a free distal end; the current collection tabs of a given series being welded together and said welded current collection tabs protrude from the winding in an extension direction defined parallel to the winding axis.;

[0017] The arrangements previously described make it possible to provide 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 in unwanted directions of the current collection tabs.

[0018] It is well understood that a current collection tab series comprises all current collection tabs aligned in a same radial direction, and that all current collection tabs in a given series are welded together.

[0019] The cell may further exhibit one or more of the following characteristics, taken alone or in combination.

[0020] According to one embodiment, the first electrode and the second electrode each comprise a metal support sheet and a layer of active material deposited on said metal support sheet, the current collecting tabs being arranged on a peripheral edge of the metal support sheet devoid of active material.

[0021] In this way, it is possible to recover all the current from the current collection tabs which are connected to the same electrode, and this, on the same side of the winding.

[0022] In one embodiment, each current collection tab is spaced from the preceding current collection tab along the peripheral edge by a variable interval that increases between an inner foil end disposed radially closest to the winding axis, and an outer foil end disposed radially farthest from the winding axis.

[0023] The arrangements described above allow current collecting 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 in a determined arrangement, which is considered more efficient for current collection.

[0024] According to one embodiment, the number of series is between two and eight.

[0025] In this way, it is possible to adjust the number of series according to the distribution of the current collection tabs around the winding axis.

[0026] According to one embodiment, the number of series is equal to four.

[0027] Advantageously, the presence of four series allows to obtain the best compromise between good current collection, guaranteed by a large number of series, and simplicity of manufacturing.

[0028] According to one embodiment, the series are angularly distributed around the winding axis in a constant manner.

[0029] In this way, it is possible to achieve a uniformly distributed current collection around the winding axis

[0030] According to one embodiment, the cell comprises at least one metal connection member, said at least one metal connection member being welded to the current collection tabs which are aligned in the same radial direction.

[0031] In this way, it is possible to make the set of current collection tabs welded together more mechanically solid.

[0032] 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.

[0033] This maximizes the exchange surface between the different current collection tabs welded together, which improves current extraction.

[0034] According to one embodiment, the cell further comprises a current collector provided with at least one opening, the current collection tabs being inserted into the at least one opening 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.

[0035] This allows for easy insertion of the current collecting tabs into the current collector, particularly for viewing the soldering of the current collecting tabs when it is implemented. It also allows for the use of a greater number of different solder types, and simplifies the manufacturing process. This operation is particularly facilitated by the fact that the current collecting tabs of a given series are soldered together and directed according to the direction of extension.

[0036] 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; a welding step during which the current collection tabs aligned in the same radial direction are welded together, and said current collection tabs welded together protrude from the winding in an extension direction defined parallel to the winding axis.

[0037] The arrangements described above make it possible to manufacture a cylindrical cell, by facilitating the step of soldering the tabs with a current collector.

[0038] Summary description of the drawings

[0039] 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: Figure 1 is a schematic view of certain steps of the method of manufacturing a battery cell according to one embodiment of the invention.

[0040] Figure 2 is a schematic view of a battery cell according to one embodiment of the invention.

[0041] Figure 3 is a schematic view of the battery cell of Figure 2.

[0042] Figure 4 is a schematic view of a battery cell according to another embodiment of the invention.

[0043] Detailed description

[0044] 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.

[0045] As can be seen in Figures 1 to 4, the invention relates to an electric battery cell 1 for an electrically powered vehicle. 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 insulating separator 25.

[0046] As can be seen in Figure 1, the first electrode 10 and the second electrode 20 may each comprise a metal support sheet 11, 21 and a layer of active material 13, 23 deposited on said metal support sheet 11, 21.

[0047] 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, arranged on a first peripheral edge 12 of the first metal support sheet 11, and devoid of active material coating.

[0048] 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 arranged on a second peripheral edge 22 of the second metal support sheet 21, and devoid of active material coating.

[0049] 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 peripheral strips without active material coating are offset on either side of the separator strips 15, 25.

[0050] The at least one stack is wound on itself around the winding axis X so as to form a substantially cylindrical winding 30.

[0051] In the winding 30, the first electrode 10 and / or the second electrode 20 comprise several series 52 each comprising a plurality of current collection tabs 50 configured to collect an electric current. The current collection tabs 50 are generally arranged on the 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 are 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. By "aligned" is meant that the current collection tabs 50 overlap angularly.A series 52 of current collection tabs 50 therefore comprises all the current collection tabs 50 aligned in the same radial direction R.

[0052] For example, each current collection tab 50 may be spaced from the current collection tab 50 preceding it along the peripheral edge 12, 22 by a variable interval denoted "NG" that increases between an inner foil end disposed radially closest to the winding axis X, and an outer foil end disposed radially farthest from the winding axis X. Such a variable interval NG may be defined by the following formula: NG = g + n * l, where g corresponds to the interval separating the current collection tab 50 closest to a winding mandrel used to wind the winding 30 and the current collection tab 50 directly succeeding it, where n corresponds to the current collection tab 50 disposed at the n ièmeplace relative to the current collection tab 50 closest to a winding mandrel, and where I corresponds to the length of increase of the winding spiral as a function of the thickness of the stack of electrodes 10, 20, and of the separator strips 15, 25. The arrangements previously described make it possible to automatically align the current collection tabs 50 of the same series 52 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 carrying out current collection.

[0053] 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 uniformly distributed current collection around the winding axis X.

[0054] 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 collection tabs 50 around the winding axis X. More particularly, 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.

[0055] The current collection tabs 50 of the same series 52 may 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.

[0056] Each current collection tab 50 extends between a proximal end 51 secured to the winding 30 and a free distal end 53. The current collection tabs 50 of a given series 52 are 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. Thus, all the current collection tabs 50 of a given series 52 are welded together. It is therefore clearly understood that the distal ends 53 are turned towards the side opposite the winding 30.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 protrude from the winding 30 on a first side of the winding 30, and for the current collection tabs 50 of the second electrode 20 to protrude from the winding 30 on a second side of the winding 30 opposite the first side. In other words, the current collection tabs 50 of each electrode 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 may further comprise a current collector 60 provided with at least one opening 61. In this case, the current collecting tabs 50 may be inserted into the at least one opening 61 on either side of the current collector 60. This operation is particularly facilitated by the fact that the current collecting tabs 50 of a given series 52 are welded together and directed in the direction of extension. 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 can open onto the contact face s60c on the one hand and onto the welding face s60s on the other hand.

[0058] Although not limiting, such an opening 61 may take the form of an insertion slot, as illustrated in FIGS. 2 and 3. By "slot" is meant 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 well understood that an insertion slot corresponds to an absence of material in the current collector 60.

[0059] Alternatively, and as shown in Figure 4, the opening 61 may take the form of at least one step 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 welding face s60s, said step having an open contour. In the same way as for the slots, each step may have 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 along this radial direction R, said greatest width being measured substantially perpendicular to this radial direction R.

[0060] Although Figures 2 and 3 show only one current collector 60, it is understood that another current collector 60 can be arranged on the side opposite the winding 30, in the same way as in Figure 4. Thus, a first current collector 60 can collect the current from the first electrode 10 via the current collection tabs 50, and a second current collector 60 can collect the current from the second electrode 20 via other current collection tabs 50. In the description, reference is sometimes made to one current collector 60, but it is understood that the arrangements that apply to this current collector 60 can apply to several current collectors 60.

[0061] 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.

[0062] Said current collection tabs 50 are then capable of electrically connecting 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. This allows easy insertion of the current collection tabs 50 into the current collector 60, in particular 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.

[0063] According to a variant not shown, 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.

[0064] 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.

[0065] All of the arrangements previously described 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 in unwanted directions of the current collection tabs 50.

[0066] The invention also relates to a method for manufacturing a cell 1 as described previously, the manufacturing method comprising: a step of providing a winding 30; a welding step during which the current collection tabs 50 aligned in the same radial direction R are welded together, and said current collection tabs 50 welded together protrude from the winding 30 in an extension direction defined parallel to the winding axis X.

[0067] The arrangements previously described make it possible to manufacture a cell 1 of cylindrical shape, by facilitating the step of soldering the tabs with a current collector 60.

[0068] Optionally, the step of providing a winding 30 may comprise: 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 spaced from the tab preceding it by the variable interval NG; a step of providing the separators 15, 25; a winding step, in which the first electrode 10, the first separator 15, the second electrode 20, and the second separator 25 are superimposed in this 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

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); said at least one stack being wound on 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 comprising a plurality of current collection tabs (50) configured to collect an electric current, the current collection 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 collection tab (50) extending between a proximal end (51) secured to the winding (30) and a free distal end (53);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) in a direction of extension defined parallel to the winding axis (X).; 2. Cell (1) according to claim 1, wherein the first electrode (10) and the second electrode (20) each comprise a metal support sheet (11, 21) and a layer of active material (13, 23) deposited on said metal support sheet (11, 21), the current collection tabs (50) being arranged on a peripheral edge (12, 22) of the metal support sheet (11, 21) devoid of active material.

3. Cell (1) according to claim 2, in which each current collecting tab (50) is spaced from the current collecting tab (50) which precedes 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, in which the number of series (52) is between two and eight.

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

6. Cell (1) according to any one of claims 1 to 5, in which 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 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).

8. Cell (1) according to any one of claims 1 to 7, in which 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).

9. Cell (1) according to any one of claims 1 to 8, further comprising a current collector (60) provided with at least one opening (61), the current collecting tabs (50) being inserted into the at least one opening (61) on either side of the current collector (60), said current collecting tabs (50) being capable of electrically connecting 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.

10. Method of manufacturing a cell (1) according to any one of claims 1 to 9, the manufacturing method comprising: - a step of providing a winding (30); - a welding step during which the current collection tabs (50) aligned in the same radial direction (R) are welded together, and said current collection tabs (50) welded together protrude from the winding (30) in an extension direction defined parallel to the winding axis (X).

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