METHOD AND DEVICE FOR THE PRODUCTION OF METAL COMPOSITE FOILS FOR BATTERY CELLS

Abstract

A method for producing a battery cell includes at least the following steps: a) reshaping a first pouch foil into a first pouch half by means of a first molding device with a first recess; b) reshaping a second pouch foil into a second pouch foil by means of a second molding device with a second recess; c) inserting a cell stack into the first molding device and the first pouch half located therein; d) bringing together the first molding device and the second molding device with the second pouch half located therein; and e) at least partially connecting the first and second pouch halves to form a battery cell.

Claims

1. A method for producing a battery cell, which includes at least the following steps: a) reshaping a first pouch foil into a first pouch half by means of a first molding device with a first recess; b) reshaping a second pouch foil into a second pouch foil by means of a second molding device with a second recess; c) inserting a cell stack into the first molding device and the first pouch half located therein; d) bringing together the first molding device and the second molding device with the second pouch half located therein; and e) at least partially connecting the first and second pouch halves to form a battery cell.

2. The method according to claim 1, wherein the reshaping of the pouch foil into a pouch half is carried out by means of an atmospheric positive pressure or negative pressure, or at least one electromagnetic pulse EMP.

3. The method according to claim 1, wherein the pouch half is fixed in the first or second molding device by means of a negative pressure.

4. The method according to claim 2, wherein the first or second molding device is heated.

5. The method according to claim 1, wherein at least two processing steps are carried out while the first and second pouch halves are in the first and second molding devices, respectively.

6. The method according to claim 1, wherein at least one of the pouch halves or the battery cell with the connected pouch halves is cut to a defined length or outer contour in the respective molding device.

7. A device for producing a battery cell comprising: a first and a second molding device and, in each case, at least one fixing device, a reshaping device, a feed device for cell stacks, a positioning device for bringing together the end faces of the molding devices, a connecting device, and a first cutting device.

8. The device according to claim 7, wherein at least one of the first and second molding devices has a heating device.

9. The device according to claim 7, wherein the first cutting device is designed at least for cutting a length or a contour of at least the pouch foil, the pouch half or the battery cell.

10. The device according to claim 7, further comprising a second cutting device for cutting an endlessly fed pouch foil.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The invention and the technical environment are explained in more detail below with reference to the accompanying figures. It should be pointed out that the invention is not intended to be limited by the exemplary embodiments mentioned. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description. In particular, it should be pointed out that the figures and in particular the proportions shown are only schematic. In the drawings:

[0042] FIG. 1: is a schematic side view of an apparatus for producing battery cells;

[0043] FIG. 2: shows the device according to FIG. 1 in a second state;

[0044] FIG. 3: shows the device according to FIG. 1 in a third state;

[0045] FIG. 4: shows the device according to FIG. 1 in a fourth state;

[0046] FIG. 5: shows the device according to FIG. 1 in a fifth state;

[0047] FIG. 6: shows the device according to FIG. 1 in a sixth state;

[0048] FIG. 7: shows the device according to FIG. 1 in a seventh state;

[0049] FIG. 8: shows the device according to FIG. 1 in an eighth state;

[0050] FIG. 9: shows the device according to FIG. 1 in a ninth state; and

[0051] FIG. 10: shows the device according to FIG. 1 in a tenth state.

DETAILED DESCRIPTION OF THE INVENTION

[0052] In FIG. 1, a device 1 for producing battery cells 2 is shown schematically in a side view. The device 1 has a first molding device 3 and a second molding device 4. From the left side, a pouch foil 5 is fed from a pouch foil supply 6 in the direction of the first and second molding devices 3, 4, so that these are covered by the pouch foil 5. The molding devices 3, 4 thereby form part of a die 7 of the device 1. The die 7 is resiliently mounted together with the first molding device 3 and the second molding device 4 and, when acted upon on its upper side, can be deflected downward with forces acting downward in the image plane. Furthermore, the device 1 is equipped with a first cutting device 8 and a second cutting device 9, the mode of operation of which will be explained later.

[0053] The first molding device 3 and the second molding device 4 are each equipped with a heating device 10 which is suitable for heating the molding devices 3, 4 to a temperature above room temperature. As a rule, pouch foils 5 consist of a composite of plastics and metals. By heating the pouch foil 5, the deep drawability of the pouch foil can be improved, so that greater degrees of reshaping can be achieved. This is precisely what is achieved by means of the heating device 10 in that the molding devices 3, 4 and thus also the pouch foil 5 are heated. The heating is preferably carried out to a temperature which is still below the melting temperature of the plastics used in the pouch foil 5.

[0054] In a bottom region of the second molding device 4, suction ducts 11 are provided, which can be subjected to a negative pressure by means of a vacuum pump (not shown) in order to draw the pouch foil 5 into a recess 12. The vacuum generated here can fulfill two functions. The first function is to support the reshaping process and to improve the deep drawability of the pouch foil 5. This is achieved by drawing out the trapped air below the pouch foil by the vacuum applied during deep drawing. This prevents a bulge in the pouch foil due to trapped air during reshaping. The second function consists in securely fixing the pouch foil 5 or a pouch half 13, 14 produced by the deep drawing process (shown in FIG. 2) in the recess 12 when the molding device is moved together with this pouch half 13, 14.

[0055] Furthermore, the second molding device 4 has a first cutting device 8 and a second cutting device 9. The first cutting device 8 is used to divide the pouch foil 5 supplied from the pouch foil supply 6 into two parts. The second cutting device 9 serves to separate the pouch foil 5 from the pouch foil supply 6.

[0056] In FIG. 2 the device 1 is shown in a second state, in which the pouch foil 5 is pressed against the die 7 by a hold-down device 15. In this state, the die 7 is shown together with the first molding device 3 and the second molding device 4 in a deflected state against a stop with a stationary die insert 21, i.e. the springs are compressed so that the pouch foil 5 is held securely between the hold-down device 15 and the die 7. The die insert 21 is used to create a flat surface for the reshaping process. During the process of lowering the hold-down device 15, the second cutting device 9 has separated the pouch foil 5 from the pouch foil supply 6. At the same time, the first cutting device 8 has separated the pouch foil 5 into a first pouch half 13 and a second pouch half 14. It can also be seen in this illustration that a first punch 16 and a second punch 17 are in a position above the pouch halves 13, 14.

[0057] FIG. 3 shows a third state in which the punches 16, 17 are moving downward and into the recesses 12. The first pouch half 13 and the second pouch half 14 are each reshaped into the recess 12, which is supported by the heat input by the heating device 10.

[0058] A fourth state is shown in FIG. 4, in which the punches 16, 17 have moved upward again and have reached their starting position again. In this process step, a cell stack 18 is inserted into the first pouch half 13. The cell stack 18 can be fed in in an automated manner, for example, by a feed device (not shown). For this purpose, for example, a conveyor belt system can feed the prefabricated cell stack 18, which can then be optionally inserted into one of the two pouch halves 13, 14 with the aid of a gripper. The pouch halves 13, 14 can be drawn in during the entire assembly process by means of the vacuum in the die 12 and can be fixed in this way. In a particularly simple embodiment, such as the one shown here, it may also be sufficient to apply a vacuum to only one molding device 14 and to fix the second pouch half 14 located therein if only this second molding device 4 is to be moved. In this case, the reshaping process in the first molding device 3 is to be carried out so slowly that the air enclosed therein can escape. The reshaping can also take place at a higher speed if simple ventilation channels are provided in the first molding device, which are suitable for guiding the air trapped between the pouch foil 5 and the die 12 to the outside of the molding device 3. In the present case, provision is made for changing the position of the second molding device 4 by means of a positioning device (not shown).

[0059] FIG. 5 shows how the second molding device 4 is pivoted to the left by means of the positioning device with an end face 19 along the arrows 20 in the direction of the end face 19 of the first molding device 3. In addition to the pivoting movement in the direction of the arrows 20, the second molding device 4 also performs a rotary movement about its horizontal longitudinal axis so that, after a complete run through the movement path predetermined by the positioning device, the end face 19 of the first molding device 3 is in direct contact with the end face 19 of the second molding device 4. This state is shown in FIG. 6. During the pivoting, the second pouch half 14 is held securely in the second molding device 4 by means of the vacuum.

[0060] In the next process step shown in FIG. 7, both molding devices 3, 4, together with the pouch halves 13, 14 and the cell stack 18 are pressed together and pivoted by 90° to the right into an upright position.

[0061] In this upright position shown in FIG. 8, the pouch halves 13, 14 of the battery cell 2 are connected to one another, i.e. the pouch halves 13, 14 are tightly connected to one another on at least three sides. This process is also referred to as sealing of the battery cell 2. The sealing of the battery cell 2 can take place in this process step using methods and devices that have already been tried and tested.

[0062] FIG. 9 shows how the molding devices 3, 4 are moved back together with the battery cells 2 after they have been connected or sealed. The positioning device initially moves all three components back to the left, so that the first molding device 3 returns to its starting position. Then, as shown in FIG. 10, the second molding device 4 is shocked to the right back into its starting position. The finished battery cell 2 is exposed and can be removed. The positioning device is designed so that it can move both the first molding device 3 and the second molding device 4 in the manner shown. This can be done, for example, by mechanical drives and gears or also by means of freely movable robots by which the molding devices 3, 4 can be detected and moved.

[0063] The present invention thus has a number of advantages. Several process steps can thus be carried out without the pouch foil 5 or the produced pouch foil halves 13, 14 having to be removed, stored, repositioned or positioned again. The separating cut from the pouch foil supply 6, the process of reshaping the pouch foil, the final cut of the outer contours, the insertion of the cell stack 18 and the process of connecting or sealing can be carried out at just a single workstation. In this case, the battery cells 2 or their components always remain within the molding devices during all process steps, so that the product quality, the cycle times and the accuracy in production are considerably improved. Furthermore, the need for handling the materials used is considerably reduced. The cell stack 18 can also be positioned substantially more precisely and better within the pouch halves 13, 14. In addition, a particularly precise final cut of the finished pouch halves 13, 14 or the finished battery cells 2 can be achieved through the suitable arrangement of cutting devices, for example in the form of blades in the die 7.

LIST OF REFERENCE SIGNS

[0064] 1 device [0065] 2 battery cells [0066] 3 first molding device [0067] 4 second molding device [0068] 5 pouch foil [0069] 6 pouch foil supply [0070] 7 die [0071] 8 first cutting device [0072] 9 second cutting device [0073] 10 heater [0074] 11 suction duct [0075] 12 recess [0076] 13 first pouch half [0077] 14 second pouch half [0078] 15 hold-down device [0079] 16 first punch [0080] 17 second punch [0081] 18 cell stack [0082] 19 end face [0083] 20 arrows [0084] 21 die insert