Cylindrical cell for electric battery and its manufacturing process

Abstract

A cylindrical electric battery cell for an electric vehicle comprising a winding of successive stacks (10) of: - a first electrode sheet (1) of a first polarity; - a first insulating separator sheet (2); - a second electrode sheet (3) of a second polarity opposite to the first polarity; - a second insulating separator sheet (4), a portion (34) of the second electrode sheet (3) extending beyond the successive stacks (10) such that said winding is substantially centered on a winding of the extending portion (34) of the second electrode sheet (3). Figure for the abbreviation: Fig. 1

Description

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

[0001] The present invention relates to the technical field of cylindrical cells for electric vehicle batteries. In particular, the invention relates to electrode sheets for such cylindrical cells. Technical background

[0002] More particularly, the present invention relates to a cylindrical battery cell, said cell comprising a casing and a roller housed in the casing, the roller delimiting a central volume around which the roller is formed by winding, the roller comprising electrodes of the cell.

[0003] The cylindrical cells are manufactured by winding around a rotating mandrel, a successive stack of at least: - a positive electrode sheet, - an insulating separator sheet, - a negative electrode sheet, - an insulating separator sheet.

[0004] The manufacture of such a cell requires high industrial precision in the sense that the housing volume in the casing to receive the roller must be suitably sized to allow the insertion of the roller into the casing and limit the movement of the roller in the casing to avoid the collapse of said roller in particular when its central volume is left empty of solid material.

[0005] “Collapse” means that the multilayer structure breaks down inside the casing, This can cause misalignment of the electrodes (particularly the first and second electrode sheets mentioned above) and the separator (particularly the first and / or second separator sheets mentioned above). In other words, the multilayer unwinds from the inside out, within the central volume.

[0006] Although current cells, when correctly sized and parameterized, generally provide satisfactory performance, they can still be improved. Indeed, changes in the dimensions and / or parameters of the electrodes alter the charge / discharge behavior of the cells. Successive charge and discharge cycles of the cell cause movement of the roller within the casing. Naturally, the central volume can vary accordingly, sometimes causing the roller to collapse within said central volume. Roller collapse reduces the cell's performance. In the worst-case scenarios, roller collapse can lead to dramatic accidents, such as explosions or fires, in particular due to short circuits caused by direct contact of electrodes at opposite potentials (in particular contact of the first and second electrode sheets mentioned above) due to misalignment of the sheets (i.e. the first electrode sheet, the first separator sheet, the second electrode sheet and the second separator sheet) of the multilayer.

[0007] Thus, there is a need to improve the cylindrical cell to improve the retention of the roller in the casing, in particular with a view to limiting the occurrence of an accident such as mentioned above.

[0008] The present invention aims to improve the retention of the roller in the casing. Summary of the invention

[0009] To this end, it is proposed, firstly, an electrode sheet intended to be integrated into a cylindrical electric battery cell for an electric vehicle, this electrode sheet comprising a metallic sheet extending longitudinally along a first axis between a first end and a second end opposite the first end, this electrode sheet being intended to be wound around a second axis substantially perpendicular to the first axis starting from the first end, the metallic sheet comprising - at the first end, an inactive transverse portion devoid of active material; - an active portion coated with an active material extending longitudinally along the first axis between the inactive transverse portion and the second end.

[0010] Various additional features may be provided, alone or in combination: - the inactive transverse portion has a length between 50mm and 250mm along the first axis; - the electrode sheet is a negative electrode sheet.

[0011] Secondly, a cylindrical electric battery cell for an electric propulsion vehicle is proposed, comprising a winding of successive stacks around a first axis of a first electrode sheet of a first polarity; of a first sheet of insulating separator; of a second electrode sheet of a second polarity opposite to the first polarity; of a second insulating separator sheet, a portion of the second electrode sheet protruding, along the first axis, from the successive stacking such that said winding around a second axis substantially perpendicular to the first axis starting from said portion is substantially centered on a winding around itself around the second axis of the portion exceeding the second electrode sheet.

[0012] Various additional features may be provided, alone or in combination: - the winding around the second axis of the overhanging portion is at least two turns; - The second electrode sheet is an electrode sheet as shown above, the protruding portion including the aforementioned transverse inactive portion. In other words, the protruding portion, along the first axis, of the successive stack includes a transverse inactive portion.

[0013] Thirdly, a method for manufacturing a cylindrical electric battery cell for an electric vehicle is proposed, this method comprising the following steps: - successive stacking along a first axis of a first electrode sheet of a first polarity; of a first sheet of insulating separator; a second electrode sheet with a second polarity opposite to the first polarity, of a second insulating separator sheet, a portion of the second electrode sheet protruding, along the first axis, from the successive stacking, - winding of the successive stack around a second axis substantially perpendicular to the first axis starting from said portion so that this winding is substantially centered on a winding around the second axis of the portion exceeding the second electrode sheet.

[0014] Various additional features may be provided, alone or in combination: - the winding around the second axis of the overhanging portion is at least two turns; - The second electrode sheet is an electrode sheet as shown above, the protruding portion including the aforementioned transverse inactive portion. In other words, the protruding portion, along the first axis, of the successive stack includes a transverse inactive portion.

[0015] Other features and advantages of the invention will become clearer and more concrete upon reading the following description of embodiments, which is made with reference to the accompanying drawings in which:

[0016] Figure [Fig.1] schematically illustrates a first successive stacking of sheets according to various embodiments;

[0017] Figure [Fig.2] schematically illustrates a second successive stacking of sheets according to various embodiments;

[0018] Figure [Fig.3] schematically illustrates a cylindrical cell according to various embodiments;

[0019] Figure [Fig.4] schematically illustrates steps in a manufacturing process for a cylindrical cell according to various embodiments. Detailed description of the invention

[0020] Referring to [Fig. 1], a successive stacking 10 is shown along a first axis 5 - of a first sheet 1 of an electrode of a first polarity, - of a first sheet 2 of an insulating separator, - of a second sheet 3 of an electrode of a second polarity opposite to the first polarity, and - a second sheet 4 of insulating separator.

[0021] The second electrode sheet 3 comprises a metallic sheet 30 (or current collector) extending longitudinally along the first axis 5 between a first end 31 and a second end 32 opposite the first end 31. In other words, the second electrode sheet 3 is substantially rectangular in shape, delimited longitudinally along the first axis 5 by a first transverse edge of end 31 and a second transverse edge of end 32 opposite and substantially parallel to the first transverse edge of end 31. The second electrode sheet 3 is intended to be wound around a second axis 6 substantially perpendicular to the first axis 5 from the first end 31.

[0022] The metallic sheet 30 comprises, at its first end 31, an inactive transverse portion 34 devoid of active material and an active portion 33 coated with an active material extending longitudinally along the first axis 5 between the inactive transverse portion 34 and the second end 32.

[0023] The second electrode foil 3 is, in one embodiment, a negative electrode foil or an anode. The second electrode foil 3 may, in this case, comprise a copper metal foil and an anode active material such as graphite or carbon.

[0024] The inactive transverse portion 34 of the second electrode sheet 3 extends, along the first axis 5 (or in the direction of the first axis 5), at least partially beyond the successive stack 10, such that the winding around the second axis 6 of the successive stack 10, starting from the portion 34, The overhang is substantially centered on a winding around the second axis 6 of the overhanging transverse inactive portion 34, as illustrated in [Fig. 3]. In other words, the transverse inactive portion 34 of the second electrode sheet 3 extends, in the successive stack 10, beyond the other sheets 1, 2, 4 along the first axis 5 (i.e., in the direction in which they are wound, namely the first axis 5 or the longitudinal direction of sheets 1-4). Consequently, when winding the successive stack 10 around a rotating mandrel, the transverse inactive portion 34 of the second electrode sheet 3 is wound first around the second axis 6, followed by sheets 1-4 of the successive stack 10.

[0025] The second electrode sheet 3 extends along the first axis 5 (that is, in a longitudinal direction of the successive stack 10), meaning that it extends beyond the other sheets 1, 2, 4 of the successive stack 10 in its longitudinal direction or, more generally, along the first axis 6. The longitudinal direction refers to the longest axis of the successive stack 10 or the direction in which this successive stack 10 is wound to form the cylindrical cell 11. More generally, the second electrode sheet 3 has, along the first axis 5, an extension allowing this second electrode sheet 3 to extend beyond the alignment of the other sheets 1, 2, 4, creating a distinct projection in the lengthwise direction of the successive stack 10 or, more generally, in the direction of the first stack axis 5.

[0026] By exceeding along the first axis 5, the inactive transverse portion 34 is advantageously pre-wound around the second axis 6 before the winding of the successive stack 10 (or initiates the winding before the successive stack 10 follows) so as to form a core (or a pillar) in the center of the resulting roll allowing to stiffen the central area of ​​the latter and thus avoid a collapse towards the inside of the cylindrical cell 11.

[0027] In one embodiment, the inactive transverse portion 34 has, along a longitudinal direction of the metal sheet or more generally along the first axis 5, a length between 50 mm and 250 mm or between 100 mm and 600 mm. Such lengths advantageously allow (depending on the perimeter of the rotating mandrel used for winding the successive stack 10 around the second axis 6) a predefined number of turns providing sufficient rigidity to the core of the cylindrical cell 11 of an electric battery for an electric vehicle.

[0028] In one embodiment, the winding of the inactive transverse portion 34 around the second axis 6 is at least two turns. At least two turns are made around the second axis 6 using the inactive portion 34. The transverse design advantageously avoids the presence of weak points around the entire inner perimeter of the roller and provides a substantially uniform resistance capable of resisting any force tending to deform the core or the central area of ​​the cylindrical cell 11.

[0029] Referring to [Fig. 4], steps of a method 12 for manufacturing the cylindrical cell 11 of an electric battery for an electric vehicle are shown. This method 12 comprises a step 41 of successively stacking along the first axis 5 of a first electrode sheet 1 of a first polarity, a first insulating separator sheet 2, a second electrode sheet 3 as shown above of a second polarity opposite to the first polarity, and a second insulating separator sheet 4. The inactive transverse portion 34 of the second electrode sheet protrudes along the first axis 5 at least partially through the successive stack 10. In other words, the second electrode sheet 3 is arranged in the successive stack 10 such that its inactive transverse portion 34 extends beyond the other sheets 1, 2, 4 in the longitudinal direction of the successive stack 10 or, more generally, along the first axis 5.

[0030] The method 12 further comprises a step 42 of winding the successive stack 10 around the second axis 6, substantially perpendicular to the first axis 5, starting from the transverse inactive portion 34, such that this winding is substantially centered on a winding around the second axis 6 of the transverse inactive portion 34, which extends along the first axis 5 of the second electrode sheet (3). The successive stack 10 is, in fact, wound around its shortest axis or, more generally, around the second axis 6, so that the resulting winding is substantially centered on a winding around the second axis 6 of the transverse inactive portion 34.In one embodiment, this involves a radial winding of the successive stack 10 around a transverse axis parallel to the width of the successive stack 10 (or, more generally, around the second axis 6) starting from the overhanging portion 34 so as to form a concentric spiral around this transverse axis.

[0031] During this winding step 42, the transverse inactive portion 34 extending along the first axis 5 is advantageously wound first around the second axis 6, followed by the sheets 1-4 of the subsequent stack 10. In other words, the transverse inactive portion 34 of the second electrode sheet 3 initiates the winding around the second axis 6 before the subsequent stack 10 follows. This advantageously results in a reinforcement of the central zone of the roll, preventing its collapse.

[0032] In one embodiment, the inactive transverse portion 34 of the second electrode sheet 3 has, along a longitudinal direction of the sheet 30 metallic or along the first axis 5, a length sufficient for it to be able to wrap around itself around the second axis 6 at least twice (of course, taking into account a predefined perimeter of the rotating chuck).

[0033] Winding the inactive transverse portion 34 around itself around the second axis 6 by at least two turns advantageously ensures a substantially uniform stiffening over the entire inner perimeter of the roller capable of resisting a possible force tending to deform the central area of ​​the cylindrical cell 11.

[0034] It should be noted that the embodiments described above are also valid for a second electrode sheet 3 without a transverse inactive portion 34. Indeed, in an alternative embodiment illustrated by [Fig. 2], the metallic sheet 30 of the second electrode sheet 3 comprises an active portion 33 coated with an active material extending longitudinally along the first axis 5 between the first end 31 and the second end 32. In other words, the metallic sheet 30 does not have a transverse inactive portion 34.

[0035] More generally, a portion 33' of the second electrode sheet 3 extends, along the first axis 5, beyond the successive stack 10 such that the winding around the second axis 6, starting from the extending portion 33', is substantially centered on a winding around itself around the second axis 6 of the extending portion 33' of the second electrode sheet 3. As described above, this advantageously results in a stiffening of the central zone of the roll, preventing its collapse.

[0036] More generally, the portion 34, 33' of the second electrode sheet 3 protruding, along the first axis 5, from the successive stack 1 0 may comprise a transverse inactive portion 34 or be a portion 33' coated at least partially with an active material.

Claims

Demands

1. Cylindrical electric battery cell (11) for an electric propulsion vehicle comprising a winding of a successive stack (10) along a first axis (5) - of a first electrode sheet (1) of a first polarity; - of a first insulating separator sheet (2); - of a second electrode sheet (3) of a second polarity opposite to the first polarity; - of a second sheet (4) of insulating separator, a portion (34, 33') of the second sheet (3) of electrode protruding, along the first axis (5), from the successive stack (10) so that said winding around a second axis (6) substantially perpendicular to the first axis (5) from said portion (34, 33') is substantially centered on a winding on itself around the second axis (6) of the portion (34, 33') protruding from the second sheet (3) of electrode.

2. Cylindrical cell (11) according to the preceding claim, characterized in that the winding around the second axis (6) of the overhanging portion (34, 33') is at least two turns.

3. Cylindrical cell (11) according to claim 1 or 2, characterized in that the second electrode sheet (3) comprises a metallic sheet (30) extending longitudinally along the first axis (5) between a first end (31) and a second end (32) opposite the first end (31), this second electrode sheet (3) being intended to be wound around the second axis (6) substantially perpendicular to the first axis (5) from the first end (31), the metallic sheet (30) comprising - at the first end (31), a transverse inactive portion (34) devoid of active material; - an active portion (33) coated with an active material extending longitudinally along the first axis (5) between the transverse inactive portion (34) and the second end (32), the overhanging portion (34, 33') comprising said transverse inactive portion (34).

4. Cylindrical cell (11) according to the preceding claim characterized in that the inactive transverse portion (34) has a length between 50mm and 250mm along the first axis (5).

5. Cylindrical cell (11) according to claim 3 or 4 characterized in that the second electrode sheet (3) is a negative electrode sheet.

6. Method (12) of manufacturing a cylindrical cell (11) according to any one of the preceding claims, this method (12) comprising the following steps: - successive stacking (41) along a first axis (5) of a first sheet (1) of electrode of a first polarity; of a first sheet (2) of insulating separator; of a second sheet (3) of electrode of a second polarity opposite to the first polarity, of a second sheet (4) of insulating separator, a portion (34, 33') of the second sheet (3) of electrode protruding, along the first axis (5), from the successive stack (10), - winding (42) on itself of the successive stack (10) around a second axis (6) substantially perpendicular to the first axis (5) from said portion (34, 33') so that this winding is substantially centered on a winding on itself around the second axis (6) of the portion (34, 33') protruding from the second sheet (3) of electrode.

7. Method (12) of manufacturing according to the preceding claim, characterized in that the winding on itself around the second axis (6) of the portion (34, 33') in overhang is at least two turns.

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