Method and unit for producing a cell for an electric battery

Description

Technical field of the invention

[0001] The invention relates to the field of rechargeable electric batteries for electric motor vehicles. In particular, the invention relates to the manufacture of electric cells intended to equip electric batteries. More specifically, the invention relates to a method and a unit for manufacturing lithium-ion electrochemical cells of the "pouch" type, i.e. cells in sachets. Technical background

[0002] Electric cells, known as "pouch" type cells, intended to equip rechargeable electric batteries can be manufactured in different ways.

[0003] One way to make these cells is to cut and then deposit electrodes of opposite polarity on top of each other, separating them with an insulating separator film.

[0004] The separator film is unwound as the electrodes are deposited on said separator film. Thus the separator film is first unwound. A first electrode is deposited. The separator film is again unwound to cover the first electrode. A second electrode of polarity opposite to the first electrode is deposited on the separator film. The separator film is then unwound again to cover the second electrode. These operations are repeated several times depending on the capacity and power requirements.

[0005] After the operation of depositing an electrode and before unrolling the separator film to cover said deposited electrode, the method generally comprises an operation of holding the electrode with holding elements. At least two holding elements press the electrode against the separator film and then the separator film is unrolled onto the electrode thus plated to cover it. Once the separator film is unrolled, the holding elements are removed to plate other electrodes.

[0006] The holding elements clamp the electrodes at the lateral ends to ensure that the mechanically tensioned separator does not damage or carry the electrode away during unwinding, given that the electrode is thin and deformable.

[0007] Although partially satisfactory, this manufacturing process still has room for improvement. The separator film, which is mechanically tensioned, is in contact with the retaining elements because the separator film is folded around the retaining elements. Sometimes, when the retaining elements are removed, they damage the separator film through friction. The separator film is then scratched or even torn.

[0008] A damaged separator film can cause very serious accidents such as fire or explosion if the defect is not detected early enough.

[0009] The invention aims to solve this drawback. Summary of the invention

[0010] To this end, a method for manufacturing a secondary battery cell is firstly proposed, comprising: a first operation of unwinding a separator film, a second operation of depositing a first electrode on the separator film, a third operation of holding a first lateral edge and a first longitudinal edge of the first electrode on the separator film by means of a first holding element and a second lateral edge opposite the first lateral edge and the first longitudinal edge of the first electrode, by means of a second holding element, a fourth operation of unwinding the separator film to cover the first electrode, a fifth operation of depositing a second electrode of polarity opposite the first electrode on the separator film, the second electrode being arranged substantially opposite the first electrode,a sixth operation of holding a third lateral edge and a third longitudinal edge of the second electrode on the separator film by means of a third holding element and a fourth lateral edge and the third longitudinal edge of the second electrode by means of a fourth holding element, a seventh operation of unwinding the separator film to cover the second electrode, an eighth operation of removing the first holding element and the second holding element, a ninth operation of removing the third holding element and the fourth holding element, in which method the operations can be repeated a plurality of times,method in which the eighth removal operation successively comprises a first lateral movement in which the first holding element and the second holding element perform a movement along a first axis parallel to the first and second lateral edges and a first moving away movement in which the first and second holding elements move away from the first electrode or, said eighth removal operation simultaneously comprises a first lateral movement in which the first holding element and the second holding element perform a movement along a first axis parallel to the first and second lateral edges and a first moving away movement in which the first and second holding elements move away from the first electrode.

[0011] The eighth removal operation, which comprises a first lateral movement along the first axis, advantageously prevents damage to the separator film. Indeed, the first holding element and the second holding element are tightly clamped by the separator film at the end of the fourth operation. Thanks to the first lateral movement along the first axis, the first and second holding elements can be released from the separator film without damaging it.

[0012] Various additional features may be provided alone or in combination: the first moving away movement is carried out along a second axis perpendicular to the first axis, said second axis being parallel to first and second longitudinal edges of the first electrode, said longitudinal edges being substantially perpendicular to the first and second lateral edges; the first holding element and the second holding element respectively come into contact with the first electrode and the separator film so that a portion of said first and second element is in contact with the first electrode and another portion of the first and second holding elements is in contact with the separator film located below the first electrode, method in which the separator film is folded around the first and second holding elements by defining a first fold line which extends along the second axis;during the first lateral movement, the first holding element and the second holding element move along the first axis from the first fold line towards the second longitudinal edge; the ninth removal operation successively comprises a second lateral movement in which the third holding element and the fourth holding element move along the first axis and a second moving away movement in which the third and fourth holding elements move away from the second electrode or, said ninth removal operation simultaneously comprises a second lateral movement in which the third holding element and the fourth holding element move along the first axis and a second moving away movement in which the third and fourth holding elements move away from the second electrode;the second moving away movement is carried out along a second axis perpendicular to the first axis, said second axis being parallel to third and fourth longitudinal edges of the second electrode, said third and fourth longitudinal edges being substantially perpendicular to the third and fourth lateral edges; the third holding element and the fourth holding element respectively come into contact with the third lateral edge and fourth lateral edge so that a portion of the third and fourth holding elements is in contact with the second electrode and another portion of the third and fourth holding elements is in contact with the separator film located below the second electrode, method in which the separator film is folded around the third and fourth holding elements by defining a second fold line which extends along the second axis;during the second lateral movement, the third holding element and the fourth holding element move along the first axis from the second fold line towards the fourth longitudinal edge; the unwinding operation and the operation of removing the first electrode are carried out simultaneously: the method comprises an initial operation of unwinding the separator film, prior to the unwinding operation and the operation of removing the first electrode; the initial operation is carried out only once during the assembly of the electrodes to form the cell. ;

[0013] Secondly, a manufacturing unit is proposed comprising: means capable of unrolling a separator film, means capable of depositing electrodes on the separator film, a first holding element, a second holding element, a third holding element and a fourth holding element, a control unit comprising a computer program capable of implementing the method described above.

[0014] Various additional features may be provided alone or in combination: the manufacturing unit comprises a mobile carriage on which the first holding element and the second holding element of the first electrode are mounted, said holding elements being gripping means capable of gripping the separator film and a first electrode simultaneously; the third holding element and the fourth holding element are distinct from the means capable of unwinding the separator film and from the means capable of depositing the second electrode. Brief description of the figures

[0015] 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: [ Fig. 1 ] there [ Fig. 1 ] is a schematic representation of a first stage of a secondary battery cell. [ Fig.2 ] there [ Fig.2 ] is a schematic representation of a second stage of the secondary battery cell of the [ Fig. 1 ]. [ Fig.3 ] there [ Fig.3 ] is a schematic representation of a method according to the invention. [ Fig.4 ] there [ Fig.4 ] is a schematic representation of a method according to one embodiment of the invention. Detailed description of the invention

[0016] On the Figures 1 and 2a first electrode 1 and a second electrode 2 of polarity opposite to the first electrode 1 are respectively represented, pressed against a separator film 3.

[0017] In the remainder of the description, we will adopt in a non-limiting manner - and without reference to Earth's gravity - longitudinal, transverse and vertical orientations, indicated by the trihedron X, Y, Z of the figures and in which: a first X axis corresponds to a first axis oriented transversely relative to the electrodes 1, 2, a second Y axis, perpendicular to the X axis, corresponds to a second axis oriented longitudinally relative to the electrodes 1, 2, a third Z axis, perpendicular to the X axis and to the Y axis. The XYZ trihedron defines the XY, XZ and YZ planes.

[0018] In the following, a method 25 for manufacturing a cell for a secondary, i.e., rechargeable, battery will be described.

[0019] In reference to the figures 3 And 4 where similar steps have the same references, the method 25 comprises a first operation O1 of unwinding a separator film 3. This first operation O1 is carried out by means of an unwinding device (not shown in the drawings). The separator film 3 is initially wound into a reel and the unwinding device unwinds it as the electrodes 1, 2 are stacked on top of each other. The unwinding device is in the form of a carriage performing a back and forth movement along the first axis X.

[0020] The method 25 comprises a second O2 operation of deposition on the separator film 3 of the first electrode 1. In the drawing of the [ Fig. 1 ], the first electrode 1 has a substantially rectangular, non-limiting shape.

[0021] The first electrode 1 includes: a first lateral edge 4 parallel to the first axis X, a second lateral edge 5 of the same length as the first lateral edge 4 and opposite the first lateral edge 4 and parallel to the first axis X, a first longitudinal edge 6 parallel to the second axis Y and longer than the first lateral edge 4 and the second lateral edge 5, and a second longitudinal edge 7 of the same length as the first longitudinal edge 6 and opposite the first longitudinal edge 6 and parallel to the second axis Y.

[0022] The method 25 comprises a third operation O3 of holding on the separator film 3, on the one hand the first lateral edge 4 and the first longitudinal edge 6 and, on the other hand the second lateral edge 5 and the first longitudinal edge 6 of the first electrode 1. The third holding operation O3 is carried out by means of a first holding element 8 and a second holding element 10.

[0023] The method 25 comprises a fourth operation O4 of unwinding the separator film 3. During the fourth operation O4, the separator film 3 is unwound to cover the first electrode 1.

[0024] The method 25 comprises a fifth operation O5 of depositing the second electrode 2 on the separator film 3. The second electrode 2 is arranged substantially opposite the first electrode 1.

[0025] The second electrode 2 comprises: a third lateral edge 18 parallel to the first axis X, a fourth lateral edge 19 of the same length as the third lateral edge 18 and opposite the third lateral edge 18 and parallel to the first axis X, a third longitudinal edge 20 parallel to the second axis Y and longer than the third lateral edge 18 and the fourth lateral edge 19, and a fourth longitudinal edge 21 of the same length as the first longitudinal edge 6 and opposite the third longitudinal edge 20 and parallel to the second axis Y.

[0026] The method 25 comprises a sixth operation O6 of holding on the separator film 3, on the one hand, the third lateral edge 18 and the third longitudinal edge 20 and, on the other hand, the fourth lateral edge 19 and the third longitudinal edge 20 of the second electrode 2. The sixth holding operation O6 is carried out by means of a third holding element 11 and a fourth holding element 12.

[0027] The method 25 comprises a seventh operation O7 of unwinding the separator film 3 to cover the second electrode 2.

[0028] The method 25 comprises an eighth operation O8 of removing the first holding element 8 and the second holding element 10.

[0029] The method 25 comprises a ninth operation O9 of removing the third holding element 11 and the fourth holding element 12.

[0030] The first, second, third, fourth, fifth, sixth, seventh, eighth and ninth operations O1 - O9 are repeated several times. Thus it becomes possible to obtain a stack of electrodes 1, 2 separated by a separator film 3. It should be noted that the operations are not necessarily carried out in the order established above. Indeed, technical adaptations of the aforementioned method 25 are likely to modify the order of the operations without this having any influence on the invention.

[0031] The eighth withdrawal operation O8 successively comprises a first lateral movement 13 and a first moving away movement 14.

[0032] During the first lateral movement 13, the first holding element 8 and the second holding element 10 both perform a movement along the first axis X. During the first moving away movement 14, the first holding element 8 and the second holding element 10 move away from the first electrode 1 by moving along the second axis Y.

[0033] Alternatively, the eighth withdrawal operation O8 simultaneously comprises a first lateral movement 13 and a first moving away movement 14.

[0034] During the first lateral movement 13, the first holding element 8 and the second holding element 10 both perform a movement along the first axis X. During the first moving away movement 14, the first holding element 8 and the second holding element 10 move away from the first electrode 1 by moving along the second axis Y. In this alternative, the first holding element 8 and the second holding element 10 each perform a first curved movement 15.

[0035] The eighth removal operation O8 which comprises a first lateral movement 13 along the X axis advantageously makes it possible not to damage the separator film 3. Indeed, the first holding element 8 and the second holding element 10 are tightly clamped by the separator film 3 at the end of the fourth operation O4. Thanks to the first lateral movement 13 along the X axis, the first and second holding elements 8, 10 can be released from the separator film 3 without damaging it.

[0036] Advantageously, the first moving away movement 14 is carried out along the second axis Y. Such a moving away movement makes it possible to quickly release the first and second holding elements 8, 10 in order to increase production rates.

[0037] As can be observed on the [ Fig. 1], the first holding element 8 is in intimate contact with both the first electrode 1 and the separator film 3. Thus, a portion of the first holding element 8 is located on the first electrode 1 while another portion of the first holding element 8 is located on the separator film 3. The separator film 3 is folded around the first and second holding elements 8, 10, defining a first folding line 16 which extends along the second axis Y.

[0038] The first holding element 8 and the second holding element 10 together prevent the first electrode 1 from being damaged by the stretched separator film 3.

[0039] Advantageously, during the first lateral movement 13, the first holding element 8 and the second holding element 10 move along the first axis X from the first folding line 16 towards the opposite side, that is to say away from the first folding line 16 in the direction of the second longitudinal edge 7 not facing said first folding line 16.

[0040] This advantageously allows the first and second holding elements 8, 10 to be extracted from the narrow, taut zone located near the first folding line 16 before initiating a final withdrawal. Thus, the risk of damaging the separator film 3 in the vicinity of the first folding line 16 is significantly reduced.

[0041] Advantageously, the ninth removal operation O9 successively comprises a second lateral movement 23 along the first axis X in which the third holding element 11 and the fourth holding element 12 move along the first axis X and a second moving away movement 24 in which the third holding element 11 and the fourth holding element 12 move away from the second electrode 2.

[0042] Alternatively, the ninth removal operation O9 simultaneously comprises a second lateral movement 23 along the first axis in which the third holding element 11 and the fourth holding element 12 move along the first axis X and a second moving away movement 24 in which the third holding element 11 and the fourth holding element 12 move away from the second electrode 2. In this alternative, the third holding element 11 and the fourth holding element 12 each perform a second curved movement 22.

[0043] The ninth removal operation O9, which includes a second lateral movement 23 along the X axis, advantageously prevents damage to the separator film 3. Indeed, the third holding element 11 and the fourth holding element 12 are tightly clamped by the separator film 3 at the end of the sixth operation O6. Thanks to the second lateral movement 23 along the X axis, the third and fourth holding elements 11, 12 can be released from the separator film 3 without damaging it.

[0044] Advantageously, the second moving away movement 24 is carried out along the second Y axis. Such a moving away movement makes it possible to quickly release the third and fourth holding elements 11, 12 in order to increase production rates.

[0045] As can be observed on the [ Fig.2], the third holding element 11 is in intimate contact with both the second electrode 2 and the separator film 3. Thus, a portion of the third holding element 11 is located on the second electrode 2 while another portion of the third holding element 11 is located on the separator film 3. The separator film 3 is folded around the first and second holding elements 11, 12, defining a second folding line 17 which extends along the second axis Y.

[0046] The third holding element 11 and the fourth holding element 12 together prevent the second electrode 2 from being damaged by the stretched separator film 3.

[0047] Advantageously, during the second lateral movement 23, the third holding element 11 and the fourth holding element 12 move along the first axis X from the second folding line 17 towards the opposite side, that is to say away from the second folding line 17 towards the fourth longitudinal edge 21 not facing said second folding line 17.

[0048] This advantageously allows the third and fourth holding elements 11, 12 to be extracted from the narrow, taut zone located near the second folding line 17 before initiating a final withdrawal. Thus the risk of damaging the separator film 3 in the vicinity of the second folding line 17 is significantly reduced.

[0049] Advantageously, in one embodiment, the operation O1 of unwinding and the operation O2 of depositing the first electrode are carried out simultaneously. In other words, the previously mentioned carriage makes it possible both to unwind the separator and to deposit the first electrode.

[0050] Thus, advantageously the carriage comprises, for example, means for gripping the separator which make it possible to grip the separator and the first electrode. Thus, when the carriage is moved, the separator is unrolled and the first electrode is moved and then placed.

[0051] Advantageously, the method 25 comprises, in an embodiment illustrated by the [ Fig.4 ], an initial operation O0 of unwinding the separator film 3. The initial operation O0 is prior to operations O1, O2.

[0052] Advantageously, the initial O0 operation is performed only once during the assembly of the electrodes to form a cell.

[0053] This initial O0 operation allows the separator film to be unrolled without a first electrode on a stacking table. Thus, during operations O1 and O2, the first electrode is deposited on the separator film unrolled during the initial O0 operation.

[0054] The first electrode is for example conveyed with the separator film 3 on one of the faces of the latter. When the gripping means of the carriage grip and then move the separator film and the first electrode together along the X axis, this has the consequence of folding the separator film 3 around the gripping means.

[0055] The invention also relates to a manufacturing unit comprising: means capable of unrolling the separator film 3, means capable of depositing electrodes on the separator film 3, a first holding element 8, a second holding element 10, a third holding element 11 and a fourth holding element 12, a control unit comprising a computer program capable of implementing the method 25 previously described.

[0056] This manufacturing unit, comprising in particular a control unit equipped with a computer program for implementing the method 25 previously described, advantageously makes it possible to significantly reduce the risk of damage to the separator film 3, thus improving the reliability of the cells thus manufactured and the safety of users.

[0057] Advantageously, in one embodiment, the manufacturing unit comprises a mobile carriage. The first holding element 8 and the second holding element 10 of the first electrode are mounted on the mobile carriage. The first holding element 8 and the second holding element 9 are in the form of gripping means capable of gripping the separator film 3 and a first electrode simultaneously.

[0058] The carriage can then move to unroll the separator film and move the first electrode simultaneously.

[0059] This helps to reduce and thus optimize production time.

[0060] Advantageously, in one embodiment, the third holding element 11 and the fourth holding element 12 are distinct from the means capable of unwinding the separator film and from the means capable of depositing the second electrode. The third holding element 11 and the fourth holding element 12 are in the form of plates.

Claims

1. Method (25) for manufacturing a cell for a secondary battery, the method comprising: - a first operation (01) of unwinding a separator film (3), - a second operation (O2) of depositing a first electrode (1) on the separator film (3), - a third operation (O3) of holding, on the separator film (3), a first lateral edge (4) and a first longitudinal edge (6) of the first electrode (1) by means of a first holding element (8), and a second lateral edge (5) opposite the first lateral edge (4) and the first longitudinal edge (6) of the first electrode (1) by means of a second holding element (10), - a fourth operation (O4) of unwinding the separator film (3) in order to cover the first electrode (1), - a fifth operation (O5) of depositing on the separator film (3) a second electrode (2) of opposite polarity to the first electrode (1), the second electrode (2) being arranged substantially opposite the first electrode (1), - a sixth operation (O6) of holding, on the separator film (3), a third lateral edge (18) and a third longitudinal edge (20) of the second electrode (2) by means of a third holding element (11), and a fourth lateral edge (19) and the third longitudinal edge (20) of the second electrode (2) by means of a fourth holding element (12), - a seventh operation (O7) of unwinding the separator film (3) in order to cover the second electrode (2), - an eighth operation (O8) of removing the first holding element (8) and the second holding element (10), - a ninth operation (O9) of removing the third holding element (11) and the fourth holding element (12), in which method the operations can be repeated a plurality of times, in which method the eighth operation (O8) of removal successively comprises a first lateral movement (13) in which the first holding element (8) and the second holding element (10) move along a first axis (X) parallel to the first and second lateral edges (4, 5) and a first movement (14) away in which the first and second holding elements (8, 10) move away from the first electrode (1) or, said eighth operation (O8) of removal simultaneously comprises a first lateral movement (13) in which the first holding element (8) and the second holding element (10) move along a first axis (X) parallel to the first and second lateral edges (4, 5) and a first movement (14) away in which the first and second holding elements (8, 10) move away from the first electrode (1).

2. Method (25) according to claim 1, wherein the first movement (14) away is carried out along a second axis (Y) perpendicular to the first axis (X), said second axis (Y) being parallel to first and second longitudinal edges (6, 7) of the first electrode (1), said longitudinal edges (6, 7) being substantially perpendicular to the first and second lateral edges (4, 5).

3. Method (25) according to either of the preceding claims, wherein the first holding element (8) and the second holding element (10) come into contact with the first electrode (1) and the separator film (3) respectively so that a portion of said first and second elements (8, 10) is in contact with the first electrode (1) and that another portion of the first and second holding elements (8, 10) is in contact with the separator film (3) located below the first electrode (1), in which method (25) the separator film (3) is folded around the first and second holding elements (8, 10), defining a first fold line (16) which extends along the second axis (Y).

4. Method (25) according to claim 3, wherein, during the first lateral movement (13), the first holding element (8) and the second holding element (10) move along the first axis (X) from the first fold line (16) towards the second longitudinal edge (7).

5. Method (25) according to any of the preceding claims, wherein the ninth operation (O9) of removal successively comprises a second lateral movement (23) in which the third holding element (11) and the fourth holding element (12) move along the first axis (X) and a second movement (24) away in which the third and fourth holding elements (11, 12) move away from the second electrode (2) or, said ninth operation (O9) of removal simultaneously comprises a second lateral movement (23) in which the third holding element (11) and the fourth holding element (12) move along the first axis (X) and a second movement (24) away in which the third and fourth holding elements (11, 12) move away from the second electrode (2).

6. Method (25) according to claim 5, wherein the second (24) movement away is carried out along a second axis (Y) perpendicular to the first axis (X), said second axis (Y) being parallel to the third and fourth longitudinal edges (20, 21) of the second electrode (2), said third and fourth longitudinal edges (20, 21) being substantially perpendicular to the third and fourth lateral edges (18, 19).

7. Method (25) according to either of claims 5 or 6, wherein the third holding element (11) and the fourth holding element (12) come into contact with the third lateral edge (18) and fourth lateral edge (19) respectively so that a portion of the third and fourth holding elements (11, 12) is in contact with the second electrode (2) and that another portion of the third and fourth holding elements (11, 12) is in contact with the separator film (3) located below the second electrode (2), in which method (25) the separator film (3) is folded around the third and fourth holding elements (11, 12), defining a second fold line (17) which extends along the second axis (Y).

8. Method (25) according to claim 7, wherein, during the second lateral movement (23), the third holding element (11) and the fourth holding element (12) move along the first axis (X) from the second fold line (17) towards the fourth longitudinal edge (21).

9. Method (25) according to any of the preceding claims, wherein the unwinding operation (01) and the operation (O2) of depositing the first electrode are carried out simultaneously.

10. Method (25) according to claim 9, wherein the method comprises an initial operation (O0) of unwinding the separator film (3), prior to the unwinding operation (01) and the operation (O2) of depositing the first electrode.

11. Method (25) according to claim 10, wherein the initial operation (O0) is carried out only once during the assembly of the electrodes to form the cell.

12. Manufacturing unit comprising: - means for unwinding a separator film (3), - means for depositing electrodes (1, 2) on the separator film (3), - a first holding element (8), a second holding element (10), a third holding element (11) and a fourth holding element (12), - a control unit comprising a computer program capable of executing a method (25) according to any of claims 1 to 11.

13. Manufacturing unit according to claim 12, wherein the unit comprises a movable carriage on which the first holding element (8) and the second holding element (10) for the first electrode are mounted, said holding elements (8, 9) being gripping means for simultaneously gripping the separator film (3) and a first electrode (1).

14. Manufacturing unit according to either of claims 12 and 13, wherein the third holding element (11) and the fourth holding element (12) are distinct from the means for unwinding the separator film and from the means for depositing a second electrode (2).