MANUFACTURING METHOD AND UNIT FOR A CELL OF AN ELECTRIC BATTERY

Description

Technical field of the invention

[0001] The invention relates to the field of rechargeable electric vehicle batteries. In particular, the invention relates to the manufacture of electrical cells for use in electric batteries. More precisely, the invention relates to a method and a manufacturing unit for pouch-type lithium-ion electrochemical cells, i.e., cells in sachets. The invention may also relate to a method and a manufacturing unit for prismatic-type lithium-ion electrochemical cells. Technical background

[0002] WO 2023 / 075328 Al discloses a method for manufacturing a cell for a secondary battery according to the preamble of claim 1.

[0003] Electric cells, such as those of the "pouch" type, i.e., cells in sachets, intended to equip rechargeable electric batteries, can be manufactured in different ways.

[0004] One way to manufacture these cells is to cut and then place electrodes of opposite polarity on top of each other, separating them with an insulating separator film.

[0005] The separator film is unrolled as the electrodes are placed on it. First, the separator film is unrolled. The first electrode is placed. The separator film is then unrolled again to cover the first electrode. A second electrode, with the opposite polarity to the first, is placed on 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.

[0006] Production rates are high in electrical cell manufacturing plants, in accordance with the commonly accepted economic model, both to achieve economies of scale and to meet the growing needs of the automotive industry. The stacking of electrodes to form an electrode stack is therefore a critical step where precision and speed work together to guarantee plant productivity, cell reliability, and end-user safety. During stacking operations in a manufacturing unit, the tools move at high speeds. Typically, a manufacturing unit can form an electrode stack of more than fifty electrodes in less than a minute. In a constant effort to increase production rates, the various movements performed by the tools are constantly being optimized.

[0007] The invention therefore aims to improve existing electrical cell manufacturing processes and units in order to increase their productivity. Summary of the invention

[0008] To this end, a manufacturing process for a secondary battery cell is proposed first, comprising: a first operation of moving a stacking table, said movement being carried out in a first direction of movement, a second operation of unwinding a separator film onto the stacking table, said separator film comprising a first electrode previously positioned on it, a third operation of moving the stacking table in a second direction of movement opposite to the first direction of movement, a fourth operation of depositing a second electrode onto the separator film, said second electrode being of opposite polarity to the first electrode, a fifth operation of moving the stacking table, in the first direction of movement, a sixth operation of unwinding the separator film so as to cover the second electrode,said separator film further comprising a first electrode pre-assembled thereon and placed on the separator film above the second electrode, a seventh operation of moving the stacking table in the second direction, , process in which the fourth, fifth, sixth, seventh operations are repeated until a stack of electrodes is formed in which the electrodes of opposite polarity are separated by the separator film.

[0009] This process makes it possible to achieve industrial production rates by reducing the number of operations. The movements of the various tools are thus optimized.

[0010] Various additional features can be provided individually or in combination: the first direction of movement is oriented vertically downwards, and the second direction of movement is oriented vertically upwards, a process in which the stacking table moves only along a substantially straight path during the stacking of the electrodes; the electrodes are arranged one on top of the other to form an electrode stack, the electrodes being separated from each other by a separator film; the second and sixth operations are initiated respectively at the end of the first and fifth operations; the fourth operation is initiated at the end of the third or seventh operation; the separator film is unwound continuously;during the first operation, the stacking table performs a vertical rectilinear translational movement in the first direction from a first high position located at a first height to a first low position and during the third operation, the stacking table performs a vertical rectilinear translational movement in the second direction from the first low position to a second high position located at a second height lower than the first height, said heights being measured from a fixed reference point in a vertical direction;in the fifth operation, the stacking table performs a vertical rectilinear translational movement in the first direction from the second high position to a second low position and in the seventh operation, the stacking table performs a vertical rectilinear translational movement in the second direction from the second low position to a third high position located at a third height lower than the second height, said heights being measured from the fixed reference point in a vertical direction; the fourth, fifth, sixth and seventh operations form a sequence, said process comprising at least two sequences so as to form a stack of electrodes in which the electrodes of opposite polarity are separated by a separator film;the sequences differ from each other such that the third height of a given sequence is greater than the first height of another sequence that immediately follows the given sequence; the stroke of the stacking table during the first operation is substantially equal to the stroke of the stacking table during the fifth operation; the stroke of the stacking table during the third operation is substantially equal to the stroke of the stacking table during the seventh operation; the first electrodes are pre-positioned on one underside of the separator film, said underside being located on the side of the stacking table.

[0011] Secondly, a manufacturing unit is proposed comprising: a mobile stacking table in translation along a rectilinear trajectory, means for moving the stacking table, means for unwinding a separator film on the stacking table, means for depositing a second electrode on the separator film, a control unit comprising a computer program capable of implementing a process as previously described.

[0012] Various additional features can be provided individually or in combination: the means for unwinding the separator film are also suitable for maintaining a first electrode, of opposite polarity to the second electrode, in contact with the separator film so as to convey said first electrode onto the stacking table or onto a second electrode. Brief description of the figures

[0013] 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: [ Fig.1 ] there [ Fig.1 ] is a side view of a schematic representation of a cell manufacturing unit according to the invention. Fig. 2 ] there [ Fig. 2 [ ] is a graph representing the operations of a process according to the invention, the x-axis being time and the y-axis being height. Fig.3 ] there [ Fig.3 ] is a front view of the manufacturing unit of the [ Fig.1 ]. Fig. 4 ] there [ Fig. 4 ] is a representation of a method according to the invention. Detailed description of the invention

[0014] On the [ Fig.1 ] is represented a unit 1 for the manufacture of electrical cells intended to be integrated into electric batteries.

[0015] Manufacturing unit 1 includes a stacking table 2. The stacking table 2 is movable in translation along a substantially rectilinear trajectory.

[0016] The manufacturing unit 1 advantageously includes means 3 for moving the stacking table 2.

[0017] Advantageously, the manufacturing unit 1 includes unwinding means 4 suitable for unwinding the separator film 7 by placing it on the stacking table 2.

[0018] Advantageously, the manufacturing unit 1 includes means 5 for depositing a second electrode 9 onto the separator film 7.

[0019] Advantageously, manufacturing unit 1 includes a control unit 1 comprising a computer program to control: the stacking table 2, the means 3 for moving the stacking table 2, the means 4 for unwinding, the means 5 for depositing.

[0020] A conveyor (not shown in the drawings) transports the first electrodes 6 so that they come into contact with the separator film 7. The first electrodes 6 are positioned on the separator film 7 before being placed on the stacking table 2. In other words, the first rectangular electrodes are positioned on the separator film, spaced apart from each other, before being placed on the stacking table.

[0021] Advantageously, the unwinding means 4 comprise two clips arranged on either side of the separator film 7. The separator film 7 comes from a reel 8.

[0022] Advantageously, the grippers are capable of simultaneously grasping the separator film 7 and a first electrode 6 so as to hold the latter against the separator film 7. The grippers can thus simultaneously unwind the separator film 7 and convey a first electrode 6 so as to deposit it on the stacking table 2 or on a second electrode 9.

[0023] In what follows, a process 12 for manufacturing a cell for a secondary battery will be described.

[0024] The manufacturing process 12 includes a first operation O1 of moving the stacking table 2 of the manufacturing unit. This movement is carried out along a first direction 10. In practice, the stacking table 2 moves vertically downwards, that is, towards the ground, on which said stacking table 2 rests. The stacking table includes a depositing face 14 which extends in a plane substantially perpendicular to the first direction.

[0025] The process 12 includes a second operation O2 of unwinding the separator film 7 onto the deposit face 14 of the stacking table 2. The separator film 7 includes a first electrode 6 previously positioned on it. The first electrode 6 is pre-positioned on the separator film 7 by means of the conveyor. During the second operation O2, the grippers each grasp the separator film 7 and the first electrode 6 and move them towards the stacking table 2 to deposit the first electrode 6 onto the stacking table 2.

[0026] Advantageously, the process 12 includes a third operation O3 of moving the stacking table 2. This movement is carried out along a second direction 11 of movement opposite to the first direction 10 of movement. In practice, the stacking table 2 moves vertically upwards, that is, away from the ground.

[0027] Advantageously, the process 12 includes a fourth operation O4 of depositing a second electrode 9 onto the separator film 7. The second electrode 9 has the opposite polarity to the first electrode 6. During this fourth operation O4, the depositing means 5 grasp a second electrode 9 from a dedicated area and then deposit it onto the separator film 7, substantially opposite the first electrode 6.

[0028] Advantageously, the process 12 includes a fifth operation O5 of moving the stacking table 2 along the first direction 10. The stacking table 2 then moves upwards away from the ground.

[0029] Advantageously, the process 12 includes a sixth operation O6 for unwinding the separator film 7. This sixth unwinding operation O6 is substantially identical to the second unwinding operation O2. Thus, during the sixth unwinding operation O6, the grippers each grasp the separator film 7 and the first electrode 6 (pre-assembled on the separator film) and move it towards the stacking table 2 to deposit the first electrode 6 onto a second electrode 9 deposited during the fourth operation O4. During the sixth operation O6, the second electrode 9 is covered by the separator film 7 by a translational movement of the grippers towards the stacking table 2, and a first electrode 6 is deposited on the separator film 7, substantially opposite the second electrode 9. It should be noted that the electrodes are not in direct contact, as the separator film 7 is positioned between them.

[0030] Advantageously, the process 12 includes a seventh operation O7 of moving the stacking table 2 along the second direction 11.

[0031] Advantageously, the fourth operation O4, the fifth operation O5, the sixth operation O6, and the seventh operation O7 are repeated to form a stack of electrodes. In this stack, the electrodes are separated by the separator film 7.

[0032] As previously mentioned, when the separator film 7 is unwound, that is, during the second operation O2 and the sixth operation O6, the first electrode 6 that is grasped by the grippers is enveloped by the separator film 7 during the movement of said grippers towards the stacking table. This is made possible by pre-positioning the first electrode 6 on the separator film 7 and in particular on a lower face 13 of said separator. The lower face 13 of the separator film 7 is defined as the one located on the side of the stacking table 2, with reference to the [ Fig.1 ].

[0033] This process 12 makes it possible to achieve industrial production rates by reducing the number of operations. The movements of the various tools are thus optimized.

[0034] Advantageously, the stacking table 2 moves only along a substantially straight trajectory during the stacking of the electrodes.

[0035] This ensures the electrode stack is secure. Other movements could cause the electrodes to become misaligned, potentially leading to short circuits. Furthermore, more complex, non-linear movements would increase manufacturing time.

[0036] The electrodes are arranged one on top of the other while being separated from each other by separator film 7.

[0037] Advantageously, the second operation O2 is initiated after the first operation O1, and the sixth operation O6 is initiated after the fifth operation O5. In other words, the second operation O2 is performed after the first operation O1, and the sixth operation O6 is performed after the fifth operation O5.

[0038] The movement of the grippers is thus optimized. They can move along the shortest path, or one of the shortest possible paths, towards the stacking table 2. This means they move almost in a straight line towards the stacking table 2, as the latter is moved downwards to allow the grippers to pass. When the stacking table 2 is moved downwards, the grippers can move above it to unwind the separator film 7 and deposit the first electrode 6.

[0039] Advantageously, the fourth operation O4 is initiated at the end of the third operation O3 or at the end of the seventh operation O7.

[0040] The movement of the 5 placement means is thus optimized. Indeed, they can move along the shortest path or one of the shortest possible paths towards the stacking table.

[0041] Advantageously, the separator film 7 is unwound continuously. In other words, the separator film 7 is not cut during the stacking operations. The separator film 7 comes from a reel 8, which is unwound by the grippers without being cut, except at the very end of the stacking process when the stack is ready to be removed from the stacking table 2.

[0042] This reduces the number of operations and thus improves production rates.

[0043] In what follows, heights are measured from a fixed reference point, along a vertical direction (for example the first direction 10 and the second direction 11).

[0044] Advantageously and with reference to the [ Fig. 2During the first operation O1, the stacking table 2 undergoes a vertical rectilinear translational movement along the first direction 10. This translational movement is initiated from a first high position P1h located at a first height H1 to a first low position P1b. During the third operation O3, the stacking table 2 undergoes a vertical rectilinear translational movement along the second direction 11. This translational movement is initiated from the first low position P1b to a second high position P2h located at a second height H2. Advantageously, the second height H2 is lower than the first height H1.

[0045] This difference between the first height H1 and the second height H2 advantageously accommodates the increased thickness of the electrode stack. In other words, the stacking table 2 does not return to its initial position (first high position P1h) to allow the passage of the grippers. Indeed, if it were to return to its initial position (first high position p1h), the grippers would be likely to strike the electrode stack, and to avoid this, it would be necessary to modify the gripper movement, which would slow down the production rate.

[0046] Advantageously and with reference to the [ Fig. 2During the fifth operation O5, the stacking table 2 performs a vertical rectilinear translational movement along the first direction. This translational movement is initiated from the second upper position P2h, located at the second height H2, to a second lower position P2b. During the seventh operation O7, the stacking table 2 performs a vertical rectilinear translational movement along the second direction 11. This translational movement is initiated from the second lower position P2b to a third upper position P3h, located at a third height H3. Advantageously, the third height H3 is lower than the second height H2.

[0047] This difference between the second height H2 and the third height H3 advantageously accommodates the increase in the thickness of the electrode stack, as previously explained.

[0048] Advantageously: the fourth operation O4, the fifth operation O5, the sixth operation O6, the seventh operation O7, form a sequence.

[0049] The process advantageously comprises at least two sequences to form a stack of electrodes separated by separator film 7.

[0050] However, the sequences are different from each other.

[0051] Advantageously, the third height H3 of a given sequence is greater than the first height H1 of another sequence that immediately follows the given sequence.

[0052] This advantageously accommodates the increased thickness of the electrode stack.

[0053] Advantageously, the stroke of the stacking table 2 during the first operation O1 is substantially equal to the stroke of the stacking table 2 during the fifth operation O5.

[0054] This allows us to obtain a stair-step motion profile with reference to the [ Fig. 2 This makes it possible to reduce unnecessary movements by limiting the travel of stacking table 2 to the bare minimum. This increases the production rate.

[0055] Advantageously, the stroke of the stacking table 2 during the third operation O3 is substantially equal to the stroke of the stacking table 2 during the seventh operation O7.

[0056] This allows us to obtain a stair-step motion profile with reference to the [ Fig. 2 This makes it possible to reduce unnecessary movements by limiting the stacking table's travel to the bare minimum. This, in turn, increases the production rate.

Claims

1. Method (12) for manufacturing a cell for a secondary battery, the method comprising: - a first operation (01) of moving a stacking table (2), said movement being carried out in a first movement direction (10), - a second operation (O2) of unwinding a separator film (7) on the stacking table (2), said separator film (7) comprising a first electrode (6) previously positioned thereon, - a third operation (O3) of moving the stacking table (2) in a second movement direction (11) opposite to the first movement direction (10), characterized in that the method comprises: - a fourth operation (O4) of putting a second electrode (9) on the separator film (7), said second electrode (9) being of opposite polarity to the first electrode (6), - a fifth operation (O5) of moving the stacking table (2) in the first movement direction (10), - a sixth operation (O6) of unwinding the separator film (7) so as to cover the second electrode (9), said separator film (7) further comprising a first electrode (6) preassembled thereon and put on the separator film (7) above the second electrode (9), - a seventh operation (O7) of moving the stacking table (2) in the second direction (11), in which method the fourth, fifth, sixth and seventh operations (O4 - O7) are repeated until an electrode stack is formed in which the electrodes of opposite polarity are separated by the separator film (7).

2. Method (12) according to claim 1, wherein the first movement direction (10) is oriented vertically downward, and the second movement direction (11) is oriented vertically upward, in which method (12) the stacking table (2) moves only along a substantially rectilinear path during the electrode stacking.

3. Method (12) according to either of the preceding claims, wherein the electrodes are arranged on top of one another to form an electrode stack, the electrodes being separated from one another by the separator film (7).

4. Method (12) according to any of the preceding claims, wherein the second operation (O2) and the sixth operation (O6) are respectively initiated at the end of the first operation (01) and the fifth operation (O5).

5. Method (12) according to any of the preceding claims, wherein the fourth operation (O4) is initiated at the end of the third operation (O3) or at the end of the seventh operation (O7).

6. Method (12) according to any of the preceding claims, wherein the separator film (7) is unwound continuously.

7. Method (12) according to any of the preceding claims, wherein, during the first operation (01), the stacking table (2) performs a vertical rectilinear translation in the first direction (10) from a first high position (P1h) located at a first height (H1) to a first low position (P1b) and, during the third operation (O3), the stacking table (2) performs a vertical rectilinear translation in the second direction (11) from the first low position (P1b) to a second high position (P2h) located at a second height (H1) which is lower than the first height (H1), said heights being measured from a fixed reference point in a vertical direction.

8. Method (12) according to claim 7, wherein, during the fifth operation (O5), the stacking table (2) performs a vertical rectilinear translation in the first direction (10) from the second high position (P2h) to a second low position (P2b) and, during the seventh operation (O7), the stacking table (2) performs a vertical rectilinear translation in the second direction (11) from the second low position (P2b) to a third high position (P3h) located at a third height (H3) which is lower than the second height (H2), said heights being measured from the fixed reference point in a vertical direction.

9. Method (12) according to any of the preceding claims, wherein the fourth, fifth, sixth and seventh operations (O4 - O7) form a sequence, said method (12) comprising at least two sequences so as to form an electrode stack in which the electrodes of opposite polarity are separated by a separator film (7).

10. Method (12) according to claim 9 in conjunction with claim 8, wherein the sequences differ from one another such that the third height (H3) of a given sequence is greater than the first height (H1) of another sequence immediately following the given sequence.

11. Method (12) according to any of the preceding claims, wherein the travel of the stacking table (2) during the first operation (01) is substantially equal to the travel of the stacking table (2) during the fifth operation (O5).

12. Method (12) according to any of the preceding claims, wherein the travel of the stacking table (2) during the third operation (O3) is substantially equal to the travel of the stacking table (2) during the seventh operation (O7).

13. Method (12) according to any of the preceding claims, wherein the first electrodes (6) are prepositioned on a lower face (13) of the separator film, said lower face (13) being located on the stacking table (2) side.

14. Manufacturing unit (1) comprising: - a stacking table (2) translatably movable along a straight path, - means (3) for moving the stacking table (2), - means (4) for unwinding a separator film (7) on the stacking table (2), - means (5) for putting a second electrode (9) on the separator film (7), - a control unit comprising a computer program capable of executing a method according to any of claims 1 to 13.

15. Unit (1) according to the preceding claim, wherein the means (4) for unwinding the separator film (7) are further capable of keeping a first electrode (6), of opposite polarity to the second electrode (9), in contact with the separator film (7) so as to convey said first electrode (6) onto the stacking table (2) or onto a second electrode (9).