Process and unit for manufacturing a cell for an electric battery

Abstract

A method for manufacturing a secondary battery cell comprising: - a first operation of unwinding a separator film (3), - a second operation of depositing a first electrode (1) onto the separator film (3), - a third operation of securing a first lateral edge (4) and a first longitudinal edge (6) of the first electrode (1) onto the separator film (3) by means of a first retaining element (8), and a second lateral edge (5) opposite to the first lateral edge (4) and the first longitudinal edge (6) of the first electrode (1) by means of a second retaining element (10), - a fourth operation of unwinding the separator film (3) to cover the first electrode (1). Figure for the abstract: Figure 1

Description

Title of the invention: Method and unit for manufacturing a cell for an electric battery 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 electrical cells intended for use in electric batteries. More precisely, the invention relates to a method and a manufacturing unit for lithium-ion electrochemical cells of the "pouch" type, that is to say, cells in a sachet. Technical background

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

[0003] One way of manufacturing these cells consists of cutting and then depositing electrodes of opposite polarity on top of each other, separating them with an insulating separator film.

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

[0005] After the electrode has been deposited and before the separator film is unrolled to cover the deposited electrode, the process generally includes an operation to hold the electrode in place with holding elements. At least two holding elements press the electrode against the separator film, and then the separator film is unrolled over the electrode thus pressed against the film to cover it. Once the separator film has been unrolled, the holding elements are removed to press other electrodes into place.

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

[0007] Although partially satisfactory, this manufacturing process can still be improved. The mechanically tensioned separator film is in contact with the retaining elements because the separator film is folded around them. When the retaining elements are removed, they sometimes damage the separator film. by friction. The separating film is then scratched, or even torn.

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

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

[0010] To this end, a method for manufacturing a secondary battery cell is proposed firstly, comprising: - a first operation involving the unwinding of a separator film, - a second deposition operation onto the separator film of a first electrode, - a third holding operation on the separating film of a first lateral edge and a first longitudinal edge of the first electrode by means of a first holding element and of a second lateral edge opposite to 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 opposite polarity to the first electrode onto the separating film, the second electrode being arranged substantially opposite the first electrode, - a sixth holding operation on the separating film of a third lateral edge and a third longitudinal edge of the second electrode by means of a third holding element and of 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 to remove the first and second support elements, - a ninth operation to remove the third and fourth support elements, a process in which operations can be repeated a plurality of times, a method in which the eighth withdrawal operation successively comprises a first lateral movement in which the first retaining element and the second retaining element move along a first axis parallel to the first and second lateral edges, and a first retraction movement in which the first and second retaining elements move away from the first electrode Or, said eighth withdrawal operation simultaneously comprises a first lateral movement in which the first retaining element and the second retaining element make a movement along a first axis parallel to the first and second lateral edges and a first recoiling movement in which the first and second retaining elements move away from the first electrode.

[0011] The eighth removal operation, which includes a first lateral movement along the first axis, advantageously avoids damaging the separating film. Indeed, the first and second retaining elements are tightly held by the separating film at the end of the fourth operation. Thanks to the first lateral movement along the first axis, the first and second retaining elements can be detached from the separating film without damaging it.

[0012] Various additional features may be provided alone or in combination:

[0013] - the first relocation movement is carried out along a second perpendicular axis dicular to the first axis, said second axis being parallel to the first and second longitudinal edges of the first electrode, said longitudinal edges being substantially perpendicular to the first and second lateral edges; - the first retaining element and the second retaining element come into contact respectively with the first electrode and the separator film so that a portion of said first and second elements is in contact with the first electrode and another portion of the first and second retaining elements is in contact with the separator film located below the first electrode, process in which the separator film is folded around the first and second retaining elements by defining a first folding line which extends along the second axis; - during the first lateral movement, the first retaining element and the second retaining element move along the first axis from the first folding line towards the second longitudinal edge; - The ninth withdrawal operation comprises successively a second lateral movement in which the third and fourth retaining elements move along the first axis, and a second retraction movement in which the third and fourth retaining elements move away from the second electrode. Or, said ninth withdrawal operation simultaneously comprises a second lateral movement in which the third retaining element and the fourth retaining element move along the first axis and a second retraction movement in which the third and fourth retaining elements move away from the second electrode; - the second relocation movement is carried out along a second axis perpendicular to the first axis, said second axis being parallel to the 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 retaining element and the fourth retaining element come into contact with the third lateral edge and the fourth lateral edge respectively, so that a portion of the third and fourth retaining elements is in contact with the second electrode and another portion of the third and fourth retaining elements is in contact with the separator film located below the second electrode, a process in which the separator film is folded around the third and fourth retaining elements, defining a second folding line which extends along the second axis; - during the second lateral movement, the third retaining element and the fourth retaining element move along the first axis from the second folding line towards the fourth longitudinal edge.

[0014] Secondly, a manufacturing unit comprising: - means capable of unrolling a separator film, - means suitable for depositing electrodes onto the separator film, - a first support element, a second support element, a third support element, and a fourth support element, - a control unit comprising a computer program capable of implementing the process described above. Brief description of the figures

[0015] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which:

[0016] [Fig-1] [Fig.1] is a schematic representation of a first stage of a cell for secondary battery.

[0017] [Fig.2] [Fig.2] is a schematic representation of a second floor of the cell for secondary battery of the [Fig.l].

[0018] [Fig.3] [Fig.3] is a schematic representation of a method according to the invention. Detailed description of the invention

[0019] Figures 1 and 2 respectively show a first electrode 1 and a second electrode 2 of opposite polarity to the first electrode 1, pressed against a separating film 3.

[0020] In the remainder of the description, the following will be adopted in a non-limiting manner - and without reference to Earth's gravity - longitudinal, transverse, and vertical orientations, indicated by the X, Y, Z trihedron in the figures and in which: - a first X axis corresponds to a first axis oriented transversely with respect to electrodes 1, 2, - a second Y axis, perpendicular to the X axis, corresponds to a second axis oriented longitudinally with respect to electrodes 1, 2, - a third axis Z, perpendicular to the X and Y axes. The XYZ trihedron defines the XY, XZ and YZ planes.

[0021] In what follows, a method 25 for manufacturing a cell for a secondary battery, i.e., rechargeable, will be described.

[0022] With reference to the drawings, the method 25 comprises a first operation 01 of unwinding a separator film 3. This first operation 01 is carried out by means of an unwinding device (not shown in the drawings). The separator film 3 is initially wound onto a reel, and the unwinding device unwinds it as the electrodes 1, 2 are stacked one on top of the other. The unwinding device is in the form of a carriage that moves back and forth along the first axis X.

[0023] The process 25 includes a second operation 02 of deposition on the separating film 3 of the first electrode 1. In the drawing of [Fig.1], the first electrode 1 has a substantially rectangular shape, not limiting.

[0024] The first electrode 1 comprises: - a first lateral edge 4 parallel to the first X axis, - a second lateral edge 5 of the same length as the first lateral edge 4 and opposite to the first lateral edge 4 and parallel to the first axis X, - a first longitudinal edge 6 parallel to the second Y-axis 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 to the first longitudinal edge 6 and parallel to the second axis Y.

[0025] The method 25 comprises, a third holding operation 03 on the separator film 3, on the one hand of the first lateral edge 4 and the first longitudinal edge 6 and, on the other hand of the second lateral edge 5 and the first longitudinal edge 6 of the first electrode 1. The third holding operation 03 is carried out by means of a first holding element 8 and a second holding element 10.

[0026] The process 25 includes a fourth operation 04 of unwinding the separator film 3. During the fourth operation 04, the separator film 3 is unwound to cover the first electrode 1.

[0027] The process 25 comprises a fifth operation 05 of depositing the second electrode 2 onto the separator film 3. The second electrode 2 is arranged substantially opposite the first electrode 1.

[0028] The second electrode 2 comprises: - a third lateral edge 18 parallel to the first X axis, - a fourth lateral edge 19 of the same length as the third lateral edge 18 and opposite to the third lateral edge 18 and parallel to the first axis X, - a third longitudinal edge 20 parallel to the second Y-axis 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.

[0029] The method 25 comprises, a sixth holding operation 06 on the separator film 3, of 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 06 is carried out by means of a third holding element 11 and a fourth holding element 12.

[0030] The process 25 includes a seventh operation 07 of unwinding the separator film 3 to cover the second electrode 2.

[0031] The process 25 includes an eighth operation 08 of removing the first retaining element 8 and the second retaining element 10.

[0032] The process 25 includes a ninth operation 09 of removing the third retaining element 11 and the fourth retaining element 12.

[0033] The first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth operations O1-O9 are repeated several times. This makes it 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 process 25 may modify the order of the operations without this having any influence on the invention.

[0034] The eighth withdrawal operation 08 comprises successively a first lateral movement 13 and a first moving-away movement 14.

[0035] During the first lateral movement 13, the first retaining element 8 and the second retaining element 10 both move along the first axis X. During the first away movement 14, the first retaining element 8 and the second retaining element 10 move away from the first electrode 1 along the second axis Y.

[0036] Alternatively, the eighth withdrawal operation 08 simultaneously comprises a first lateral movement 13 and a first moving-away movement 14.

[0037] During the first lateral movement 13, the first retaining element 8 and the second retaining element 10 both perform a movement according to the first axis X. During the first movement 14 away, 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.

[0038] The eighth removal operation 08, which includes a first lateral movement 13 along the X-axis, advantageously avoids damaging the separator film 3. Indeed, the first retaining element 8 and the second retaining element 10 are tightly held by the separator film 3 at the end of the fourth operation 04. Thanks to the first lateral movement 13 along the X-axis, the first and second retaining elements 8, 10 can be detached from the separator film 3 without damaging it.

[0039] Advantageously, the first 14 relocation movement is carried out along the second axis Y. Such a relocation movement makes it possible to quickly release the first and second holding elements 8, 10 in order to increase production rates.

[0040] As can be seen in [Fig. 1], the first retaining element 8 is in close contact with both the first electrode 1 and the separator film 3. Thus, a portion of the first retaining element 8 is located on the first electrode 1, while another portion of the first retaining element 8 is located on the separator film 3. The separator film 3 is folded around the first and second retaining elements 8, 10, defining a first fold line 16 that extends along the second Y-axis.

[0041] The first retaining element 8 and the second retaining element 10 together prevent the first electrode 1 from being damaged by the stretched separator film 3.

[0042] Advantageously, during the first lateral movement 13, the first retaining element 8 and the second retaining element 10 move along the first axis X from the first folding line 16 towards the opposite side, i.e. away from the first folding line 16 towards the second longitudinal edge 7 not facing said first folding line 16.

[0043] This advantageously allows the first and second retaining elements 8, 10 to move out of the narrow tensioned zone located near the first fold line 16 before initiating a final retraction. Thus, the risk of damaging the separator film 3 in the vicinity of the first fold line 16 is significantly reduced.

[0044] Advantageously, the ninth withdrawal operation 09 successively comprises a second lateral movement 23 along the first axis X in which the third retaining element 11 and the fourth retaining element 12 move along the first axis X and a second retraction movement 24 in which the third retaining element 11 and the fourth retaining element 12 move away from the second electrode 2.

[0045] Alternatively, the ninth withdrawal operation 09 simultaneously comprises a second lateral movement 23 along the first axis in which the third retaining element 11 and the fourth retaining element 12 move along the first axis X and a second recoil movement 24 in which the third retaining element 11 and the fourth retaining element 12 move away from the second electrode 2. In this alternative, the third retaining element 11 and the fourth retaining element 12 each perform a second curved movement 22.

[0046] The ninth removal operation 09, which includes a second lateral movement 23 along the X-axis, advantageously avoids damaging the separator film 3. Indeed, the third retaining element 11 and the fourth retaining element 12 are tightly held by the separator film 3 at the end of the sixth operation 06. Thanks to the second lateral movement 23 along the X-axis, the third and fourth retaining elements 11, 12 can be detached from the separator film 3 without damaging it.

[0047] Advantageously, the second relocation movement 24 is carried out along the second axis Y. Such a relocation movement makes it possible to quickly release the third and fourth holding elements 11, 12 in order to increase production rates.

[0048] As can be seen in [Fig. 2], the third retaining element 11 is in close contact with both the second electrode 2 and the separator film 3. Thus, a portion of the third retaining element 11 is located on the second electrode 2, while another portion of the third retaining element 11 is located on the separator film 3. The separator film 3 is folded around the first and second retaining elements 11, 12, defining a second fold line 17 that extends along the second Y-axis.

[0049] The third retaining element 11 and the fourth retaining element 12 together prevent the second electrode 2 from being damaged by the stretched separator film 3.

[0050] Advantageously, during the second lateral movement 23, the third retaining element 11 and the fourth retaining element 12 move along the first axis X from the second folding line 17 towards the opposite side, i.e. away from the second folding line 17 towards the fourth longitudinal edge 21 not facing said second folding line 17.

[0051] This advantageously allows the third and fourth retaining elements 11, 12 to extricate themselves from the narrow tensioned zone located near the second folding line 17 before initiating a final retraction. Thus, the risk of damaging the film 3 separator in the vicinity of the second line 17 of folding is significantly reduced.

[0052] The invention also relates to a manufacturing unit comprising: - means for unwinding the separator film 3, - means for depositing electrodes on the separator film 3, - a first retaining element 8, a second retaining element 10, a third retaining element 11 and a fourth retaining element 12, - a control unit comprising a computer program capable of implementing the process 25 described above.

[0053] This manufacturing unit, including in particular a control unit equipped with a computer program for the implementation of the process 25 described above, 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 the users.

Claims

Claims

1. A method (25) of manufacturing a cell for a secondary battery comprising: - a first operation (01) of unwinding a separator film (3), - a second operation (02) of depositing a first electrode (1) on the separator film (3), - a third operation (03) 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 (04) of unwinding the separator film (3) to cover the first electrode (1), - a fifth operation (05) of depositing on the separator film (3) a second electrode (2) of polarity opposite to the first electrode (1), the second electrode (2) being arranged substantially opposite the first electrode (1), - a sixth operation (06) 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 (07) of unwinding the separator film (3) to cover the second electrode (2), - an eighth operation (08) of removing the first holding element (8) and the second holding element (10), - a ninth operation (09) 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, method in which the eighth removal operation (08) successively comprises a first lateral movement (13) in which the first holding element (8) and the second holding element (10) perform a movement along a first axis (X) parallel to the first and second lateral edges (4, 5) and a first movement (14) removal in which the first and second holding elements (8, 10) move away from the first electrode (1) or, said eighth removal operation (08) simultaneously comprises a first lateral movement (13) in which the first holding element (8) and the second holding element (10) perform a movement along a first axis (X) parallel to the first and second lateral edges (4, 5) and a first removal movement (14) in which the first and second holding elements (8, 10) move away from the first electrode (1).

2. Method (25) according to claim 1 in which the first movement (14) of moving 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 (1) electrode, said longitudinal edges (6, 7) being substantially perpendicular to the first and second lateral edges (4, 5).

3. Method (25) according to any one of the preceding claims in which the first holding element (8) and the second holding element (10) respectively come into contact with the first electrode (1) and the separator film (3) so that a portion of said first and second elements (8, 10) is in contact with the first electrode (1) and 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), method (25) in which the separator film (3) is folded around the first and second holding elements (8, 10) by defining a first folding 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 folding line (16) towards the second longitudinal edge (7).

5. Method (25) according to any one of the preceding claims in which the ninth removal operation (09) 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 moving away movement (24) wherein the third and fourth holding elements (11, 12) move away from the second electrode (2) or, said ninth removal operation (09) 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 moving away movement (24) in which the third and fourth holding elements (11, 12) move away from the second electrode (2).

6. Method (25) according to claim 5 in which the second (24) moving away movement is carried out along a second axis (Y) perpendicular to the first axis (X), said second axis (Y) being parallel to 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 any one of claims 5 or 6 in which the third holding element (11) and the fourth holding element (12) come into contact with the third lateral edge (18) and the 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 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), method (25) in which the separator film (3) is folded around the third and fourth holding elements (11, 12) by defining a second folding 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 folding line (17) towards the fourth longitudinal edge (21).

9. Manufacturing unit comprising: - means capable of unwinding a separator film (3), - means capable of 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 implementing a method (25) according to any one of claims 1 to 8.

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