Electrode rolling unit and process implementing such a unit

Abstract

A continuous flow rolling unit (1) for an electrode (2) comprising an active portion coated with an active material and a first metallic portion not coated with an active material, said rolling unit (1) comprising: - a main rolling device (7) adapted to roll the active portion, and - an anti-ripple device (8), separate from the main device (7), and adapted to roll the first metallic portion, rolling unit (1) wherein the anti-ripple device (8) is arranged upstream of the main device (7) in a direction of movement of the electrode (2). Figure for the abbreviation: Figure 1

Description

Title of the invention: Electrode rolling unit and method implementing such a unit Technical field of the invention

[0001] The invention relates to the field of electric batteries for electric motor vehicles. In particular, the invention relates to an electrode rolling unit and its method of implementation. Technical background

[0002] Electrodes are essential elements of electric battery cells. Whether they are wound cells (electrode sheets wrapped around a mandrel) or stacked cells (electrode sheets cut and stacked on top of each other), the electrodes are in the form of metal sheets partially coated with an active material.

[0003] The metal sheet is initially wound on itself in the form of a coil. Once unwound, the metal sheet is partially coated with active material. Thus the electrode comprises an active portion corresponding to the metal sheet coated with active material and two metal portions, corresponding to the metal sheet not coated with active material. The metal portions are located on either side of the active portion.

[0004] The electrode is then conveyed to a continuous flow rolling unit. The rolling unit comprises two counter-rotating rollers, between which the electrode passes in a continuous flow. The electrode is subjected to mechanical pressure there, resulting in mechanical deformation.

[0005] The thickness of the electrode is not uniform. In fact, the active portion has a thickness greater than the thickness of each of the metal portions.

[0006] Thus when the electrode is rolled in the rolling unit, it is first the active portion which undergoes the mechanical pressure due to its thickness. The active portion is therefore elongated while the metal portions undergo no or less mechanical pressure. The mechanical pressure on the active portion therefore propagates laterally towards the metal portions. This can then cause: - ripples on the metal portion due to uncontrolled deformation (“wrinkles” in English); and / or - a rupture of the metal foil of the electrode due to excessive stresses coming from the metal portions.

[0007] Cell manufacturers wish to avoid, as much as possible, the formation of ripples in the metal portions or the breakage of the metal foil.

[0008] When the defect is detected, whether it is ripples or breakage of the metal sheet, the electrodes are scrapped, the lines are shut down for a certain time, affecting production and burdening the overall efficiency of the factory.

[0009] As for ripples, if they are not detected, they can damage the separator, which can cause short circuits, then causing a major risk of explosion of the cell during use.

[0010] The invention therefore aims to solve the aforementioned problems. Summary of the invention

[0011] To this end, there is proposed firstly a unit for continuous flow rolling of an electrode comprising an active portion coated with an active material and a first metal portion not coated with an active material, said rolling unit comprising: - a main rolling device capable of rolling the active portion, and - an anti-corrugation device, separate from the main device, and capable of rolling the first metal portion, rolling unit in which the anti-ripple device is arranged upstream of the main device in a direction of movement of the electrode.

[0012] Such a rolling unit makes it possible to roll the first metal portion before the active portion. Thus, the first metal portion is deformed (elongated) under the effect of the mechanical pressure it undergoes in the anti-ripple device. Thus, when the active portion is in turn deformed under the effect of the mechanical pressure it undergoes in the main device, the first metal portion, already deformed in the anti-ripple unit, will not tend to deform even more. This makes it possible to avoid the formation of ripples in the first metal portion and / or the breaking of the electrode.

[0013] Various additional features may be provided alone or in combination: - the anti-ripple device is capable and intended to exert a first pressure force on the first metal portion, the main device is capable of exerting a second pressure force on the active portion, unit in which the first pressure force is calibrated so that in the anti-ripple device, the first metal portion extends by a distance at least equal to an extension of the active portion in the main device; - the anti-ripple device comprises a first rotating roller having a first diameter and a second rotating roller having a second diameter defining between them a passage through which the electrode passes in a continuous flow, unit in which the first roller comprises at least a first annular ring having a diameter exterior greater than the first diameter, said first annular ring being intended to come into contact with the first metal portion of the electrode, so that said first metal portion undergoes rolling; - the first rotating roller comprises a second annular ring having an outside diameter greater than the first diameter, said second annular ring being intended to come into contact with a second metal portion of the electrode, distinct from the first metal portion, so that said second metal portion undergoes rolling; - the second rotating roller comprises a third annular ring having an outside diameter greater than the second diameter, said third annular ring being intended to come into contact with the first metal portion of the electrode, so that said first metal portion undergoes rolling, in which unit, the third annular ring is arranged opposite the first annular ring; - the second rotating roller comprises a fourth annular ring having an outer diameter greater than the second diameter, said fourth annular ring being, so that said second metal portion undergoes rolling, unit in which, the fourth annular ring is arranged opposite the second annular ring; - a distance separating the first rotating roller from the second rotating roller is greater than a thickness of the active portion, so that the active portion does not undergo any mechanical deformation in the anti-ripple device; - the anti-ripple device includes: - a first pair of rotating rollers comprising a first rotating upper roller and a first rotating lower roller, and - a second pair of rotating rollers comprising a second rotating upper roller and a second rotating lower roller, anti-ripple device in which the first pair of rotating rollers and the second pair of rotating rollers respectively define a first space in which the first metal portion passes in a continuous flow and a second space in which a second metal portion passes in a continuous flow, not coated with an active material, so that said metal portions undergo mechanical deformation; - the first upper roller and the second upper roller are spaced apart by a first distance greater than or equal to a width of the active portion, - the first lower roller and the second lower roller are spaced apart by a second distance greater than or equal to the width of the active portion, so that the active portion of the electrode does not undergo any mechanical deformation during its passage through the anti-ripple device.

[0014] Secondly, a method for continuous flow rolling of an electrode comprising an active portion coated with an active material and a first metal portion not coated with an active material is proposed, the method implementing a rolling unit as previously described, said method comprising: - a main rolling operation of the active portion, - a first preliminary operation of rolling the first metal portion, said first preliminary operation being carried out before the main operation, in the direction of movement of the electrode.

[0015] Various additional features may be provided alone or in combination: - a first pressure force exerted by an anti-ripple device is calibrated so that in the anti-ripple device, the first metal portion extends by a distance at least equal to an extension of the active portion in a main device; - this comprises a second preliminary rolling operation of a second metal portion of the electrode, said second preliminary rolling operation being carried out at the same time as the first preliminary operation. Brief description of the figures

[0016] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0017] [Fig-1] [Fig.l] is a schematic representation of a rolling unit comprising an anti-ripple device according to the invention,

[0018] [Fig.2] [Fig.2] is a schematic representation of the anti-ripple device according to a first embodiment of the invention,

[0019] [Fig.3] [Fig.3] is a schematic representation of the anti-ripple device according to a second embodiment of the invention,

[0020] [Fig.4] [Fig.4] is a schematic representation of a method according to the invention. Detailed description of the invention

[0021] In [Fig.l] a unit 1 for continuous flow rolling of an electrode 2 is shown. “Continuous flow” means that the electrode 2 is rolled so that it passes continuously in the rolling unit 1.

[0022] The electrode 2 comprises an active portion 3, a first metallic portion 4 and a second metallic portion 5. The first metallic portion 4 and the second metallic portion 5 are arranged on either side of the active portion 3. The active portion 3 is coated with an active material 6. The first metallic portion 4 and the second metallic portion 5 are not coated with active material 6. In other terms, the electrode 2 is in the form of a metal sheet (typically copper or aluminum) of which a part is coated with an active material 6 and other parts are not coated with an active material 6, thus leaving the metal sheet visible.

[0023] The rolling unit comprises: - a main rolling device 7 suitable and intended to roll the active portion 3 of the electrode, and - an anti-corrugation device 8, separate from the main device 7, and capable of rolling the first metallic portion 4.

[0024] As can be seen in [Fig.l], the anti-ripple device 8 is arranged upstream of the main device 7 in a direction of movement of the electrode 2 represented by an arrow 9.

[0025] Such a rolling unit 1 makes it possible to roll the first metal portion 4 before the active portion 3. Thus, the first metal portion 4 is deformed (elongated) under the effect of the mechanical pressure that it undergoes in the anti-ripple device 8. Thus, when the active portion 3 is in turn deformed under the effect of the mechanical pressure that it undergoes in the main device 7, the first metal portion 4, already deformed in the anti-ripple unit 8, will not have a tendency to deform even more. This makes it possible to avoid the formation of ripples in the first metal portion 4 and / or the breaking of the electrode 2.

[0026] Advantageously, the anti-ripple device 8 is capable and intended to exert a first pressure force on the first metal portion 4 and on the second metal portion 5. The main device 7 is capable of exerting a second pressure force on the active portion 3. The second pressure force is calibrated so as to achieve predetermined technical specifications in the active material 6, typically a given density. The first pressure force is advantageously calibrated so that in the anti-ripple device 8, the first and second metal portions 4, 5 elongate by a distance at least equal to the elongation of the active portion 3 in the main device 7.

[0027] This makes it possible to avoid the formation of ripples in the first metal portion 4 and in the second metal portion 5.

[0028] In a first embodiment shown in [Fig. 2], the anti-ripple device 8 comprises a first rotating roller 10 having a first diameter DI and a second rotating roller 11 having a second diameter D2. The first rotating roller 10 and the second rotating roller 11 define between them a passage 12 through which the electrode 2 passes in a continuous flow. As can be seen in the drawing of [Fig. 2], the first roller 10 comprises a first annular ring 13. An outer diameter of the first annular ring 13 is greater than the first diameter DI of the first roller 10. The first annular ring 13 is intended to come into contact with the first metallic portion 4 of the electrode 2. Thus the first metallic portion 4 undergoes rolling in the anti-ripple device 8, while the active portion 3 undergoes little or no mechanical pressure in the anti-ripple device 8.

[0029] The first annular ring 13, the diameter of which is greater than that of the first roller 10, advantageously makes it possible to deform only the first metallic portion 4 in the anti-ripple device 8, the active portion 3 undergoing little or no mechanical pressure in the anti-ripple device 8.

[0030] Advantageously, the first rotating roller 10 comprises a second annular ring 14 having an outside diameter greater than the first diameter DI of the first rotating roller 10. The second annular ring 14 is intended to come into contact with the second metal portion 5 of the electrode 2. Thus the second metal portion 5 undergoes rolling in the anti-ripple device 8.

[0031] The second annular ring 14, the diameter of which is greater than that of the first roller 10, advantageously makes it possible to deform only the second metallic portion 5 in the anti-ripple device 8, the active portion 3 undergoing little or no mechanical pressure in the anti-ripple device 8.

[0032] The first pressure force is calibrated so that in the anti-ripple device 8, the first metal portion 4 and the second metal portion 5 are elongated by a distance at least equal to the elongation of the active portion 3 in the main device 7. In other words, if the elongation of the active portion 3 is equal to K, then the elongation of the first metal portion 4 will be K / 2 and that of the second metal portion 5 will be K / 2. A different distribution is possible.

[0033] Advantageously, the second rotating roller 11 comprises a third annular ring 15. The third annular ring 15 has an outside diameter greater than the second diameter D2 of the second roller 11. The third annular ring 15 is intended to come into contact with the first metal portion 4 of the electrode 2. Thus the first metal portion 4 undergoes rolling on either side of its sides in the anti-corrugation unit 8. As can be seen in [Fig.2], the third annular ring 15 is arranged opposite the first annular ring 13.

[0034] The third annular ring 15, the diameter of which is greater than that of the second roller 11, advantageously makes it possible to deform only the first metallic portion 4 in the anti-ripple device 8, the active portion 3 undergoing little or no mechanical pressure in the anti-ripple device 8.

[0035] Advantageously, the second rotating roller 11 comprises a fourth annular ring 16. The fourth annular ring 16 has an outside diameter greater than the second diameter D2 of the second roller 11. The fourth annular ring 16 is intended to come into contact with the second metallic portion 5 of the electrode 2. Thus the second metallic portion 5 undergoes rolling on either side of its sides in the anti-ripple unit 8. As can be seen in [Fig.2], the fourth annular ring 16 is arranged opposite the second annular ring 14.

[0036] The fourth annular ring 16, the diameter of which is greater than that of the second roller 11, advantageously makes it possible to deform only the second metallic portion 5 in the anti-ripple device 8, the active portion 3 undergoing little or no mechanical pressure in the anti-ripple device 8.

[0037] Advantageously, a distance 17 separating the first roller 10 from the second roller 11 is greater than a thickness of the active portion 3. Thus the active portion 3 does not undergo any mechanical deformation during its passage through the anti-corrugation device 8.

[0038] In a second embodiment shown in [Fig.3], the anti-ripple device 8 comprises: - a first pair 18 of rotating rollers, and - a second pair 19 of rotating rollers.

[0039] The first pair 18 of rotating rollers comprises a first rotating upper roller 20 and a first rotating lower roller 21.

[0040] The second pair 19 of rotating rollers comprises a second upper rotating roller 22 and a second lower rotating roller 23.

[0041] The first pair 18 of rotating rollers defines a first space 24 between the first upper roller 20 and the first lower roller 21 in which the first metal portion 4 passes in a continuous flow.

[0042] The second pair 19 of rotating rollers defines a second space 25 between the second upper roller 22 and the second lower roller 23 in which the second metal portion 5 passes in a continuous flow.

[0043] Thus the first metallic portion 4 and the second metallic portion 5 undergo mechanical deformation in the anti-ripple device 8.

[0044] Advantageously, the first upper roller 20 and the second upper roller 22 are spaced apart by a first distance 26, greater than or equal to a width L of the active portion 3.

[0045] Advantageously, the first lower roller 21 and the second lower roller 23 are spaced apart by a second distance 27 greater than or equal to the width L of the active portion. R

[0046] Thus the active portion 3 does not undergo any pressure force, and therefore no mechanical deformation in the anti-ripple device 8.

[0047] In the following, a method 31 for rolling an electrode 2 using the unit 1 previously described will be described.

[0048] In [Fig. 4], a method 31 for continuous flow rolling of an electrode 2 is shown. The electrode 2 comprises an active portion 3 coated with an active material 6 and a first metallic portion 4 not coated with active material. The method comprises: - a main rolling operation 28 of the active portion 3, carried out by means of the main rolling device 7, - a first preliminary rolling operation 30 of the first metallic portion 4.

[0049] The first preliminary operation 28 is carried out before the main operation 28 according to the direction of movement of the electrode.

[0050] Such a rolling method makes it possible to roll the first metal portion 4 before the active portion 3. Thus, the first metal portion 4 is deformed (elongated) under the effect of the mechanical pressure that it undergoes in the anti-ripple device 8. Thus, when the active portion 3 is in turn deformed under the effect of the mechanical pressure that it undergoes in the main device 7, the first metal portion 4, already deformed in the anti-ripple unit 8, will not have a tendency to deform even more. This makes it possible to avoid the formation of ripples in the first metal portion 4 and / or the breaking of the electrode 2.

[0051] Advantageously, a first pressure force exerted by the anti-ripple device 8 is calibrated so that in the anti-ripple device 8, the first metal portion 4 extends by a distance at least equal to an extension of the active portion 3 in the main device 7.

[0052] Advantageously, the method comprises a second preliminary rolling operation 30 of the second metal portion 5. This second preliminary rolling operation 30 is carried out at the same time as the first preliminary operation 29, consequently, the second preliminary operation 30 is carried out before the main operation 28 in the direction of movement of the electrode. The pressure force exerted on the first metal portion 4 and the pressure force exerted on the second metal portion 5 are substantially equal.

Claims

Claims

1. Unit (1) for continuous flow rolling of an electrode (2) comprising an active portion (3) coated with an active material (6) and a first metallic portion (4) not coated with an active material, said rolling unit (1) comprising: - a main rolling device (7) capable of rolling the active portion (3), and - an anti-ripple device (8), separate from the main device (7), and capable of rolling the first metallic portion (4), rolling unit (1) in which the anti-ripple device (8) is arranged upstream of the main device (7) in a direction of movement of the electrode (2).

2. Rolling unit (1) according to claim 1 in which the anti-ripple device (8) is capable and intended to exert a first pressure force on the first metal portion (4), the main device (7) is capable of exerting a second pressure force on the active portion (3), unit (1) in which the first pressure force is calibrated so that in the anti-ripple device (8), the first metal portion (4) elongates by a distance at least equal to an elongation of the active portion (3) in the main device (7).

3. Rolling unit (1) according to any one of the preceding claims, in which the anti-ripple device (8) comprises a first rotating roller (10) having a first diameter (D1) and a second rotating roller (11) having a second diameter (D2) defining between them a passage (12) through which the electrode (1) passes in a continuous flow, unit (1) in which the first roller (10) comprises at least one first annular ring (13) having an external diameter greater than the first diameter (D1), said first annular ring (13) being intended to come into contact with the first metal portion (4) of the electrode, so that said first metal portion (4) undergoes rolling.

4. Rolling unit (1) according to claim 3 wherein the first rotating roller (10) comprises a second annular ring (14) having an outside diameter greater than the first diameter (D1), said second annular ring (14) being intended to come into contact with a second metallic portion (5) of the electrode, distinct from the first metallic portion (4), so that said second metallic portion (5) metal undergoes rolling.

5. Rolling unit (1) according to any one of claims 3 or 4 wherein the second rotating roller (11) comprises a third annular ring (15) having an outside diameter greater than the second diameter (D2), said third annular ring (15) being intended to come into contact with the first metal portion (4) of the electrode, so that said first metal portion (4) undergoes rolling, unit (1) in which the third annular ring (15) is arranged opposite the first annular ring (13).

6. Rolling unit (1) according to claim 5 further dependent on claim 4 wherein, the second rotating roller (23) comprises a fourth annular ring (16) having an outer diameter greater than the second diameter (D2), said fourth annular ring (16) being, so that said second metallic portion (5) undergoes rolling, unit (1) in which, the fourth annular ring (16) is arranged opposite the second annular ring (14).

7. Rolling unit (1) according to any one of claims 3 to 6 wherein a distance (17) separating the first rotating roller (10) from the second rotating roller (11) is greater than a thickness of the active portion (3), so that the active portion (3) does not undergo any mechanical deformation in the anti-corrugation device.

8. Rolling unit (1) according to any one of claims 1 or 2 wherein the anti-corrugation device (8) comprises: - a first pair (18) of rotating rollers comprising a first rotating upper roller (20) and a first rotating lower roller (21), and - a second pair (19) of rotating rollers comprising a second rotating upper roller (22) and a second rotating lower roller (23), anti-corrugation device (8) in which the first pair (18) of rotating rollers and the second pair (19) of rotating rollers respectively define a first space (24) in which the first metal portion (4) passes in a continuous flow and a second space (25) in which a second metal portion (5) passes in a continuous flow, not coated with an active material, so that said metal portions (4, 5) undergo mechanical deformation.

9. Rolling unit (1) according to claim 8 wherein: - the first upper roller (20) and the second upper roller (22) are spaced apart by a first distance (26) greater than or equal to a width (L) of the active portion (3), - the first lower roller (21) and the second lower roller (23) are spaced apart by a second distance (27) greater than or equal to the width of the active portion (3), so that the active portion (3) of the electrode (2) does not undergo any mechanical deformation during its passage through the anti-ripple device (8).

10. Method (31) for continuous flow rolling of an electrode (2) comprising an active portion (3) coated with an active material (6) and a first metallic portion (4) not coated with an active material, the method (31) implementing a rolling unit (1) according to claim 1, said method (31) comprising: - a main operation (28) of rolling the active portion (3), - a first preliminary operation (29) of rolling the first metallic portion (4), said first preliminary operation (29) being carried out before the main operation (28), in the direction of movement of the electrode (2).

11. Method (31) according to claim 10, implementing a unit (1) according to claim 2, method in which, a first pressure force exerted by an anti-ripple device (8) is calibrated so that in the anti-ripple device (8), the first metallic portion (4) elongates by a distance at least equal to an elongation of the active portion (3) in a main device (7).

12. Method (31) according to claim 11, implementing a unit according to any one of claims 4 to 9 wherein, it comprises a second preliminary operation (30) of rolling a second metallic portion (5) of the electrode (2), said second preliminary rolling operation (30) being carried out at the same time as the first preliminary operation (29).

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