METHOD FOR PRODUCING BATTERY ELECTRODES

Abstract

A method for producing battery electrodes, in which an electrode strip material comprising a foil and comprising an active material coating applied thereto is separated at predetermined cutting points to form a number of battery electrodes, wherein the electrode strip material is conveyed on a planar vacuum belt in a conveying direction to a cutting gap, wherein, in a first method step, the active material coating of a cutting point is partially ablated using a first laser beam before the cutting point reaches the cutting gap, and wherein, in a second method step, the active material coating and the foil of the cutting point are completely severed using a second laser beam when the cutting point is in the region of the cutting gap.

Claims

1. A method for producing battery electrodes, comprising: separating an electrode strip material comprising a foil and an active material coating applied thereto at predetermined cutting points (to form a number of battery electrodes, conveying the battery electrodes on a planar vacuum belt in a conveying direction to a cutting gap, partially ablating the active material coating of a cutting point using a first laser beam before the cutting point reaches the cutting gap, and severing the active material coating and the foil of the cutting point using a second laser beam when the cutting point is in the region of the cutting gap.

2. The method according to claim 1, further comprising moving the first laser beam and/or the second laser beam along the cutting point by means of a polygon scanner.

3. The method according to either claim 1, further comprising guiding the first laser beam over the cutting point several times in succession during the partially ablating step.

4. The method according to claim 1, further comprising guiding the second laser beam over the cutting point several times in succession during the severing step.

5. The method according to claim 1, wherein the first method step and/or the second method step are carried out without interrupting the conveyance of the vacuum belt.

6. A device for producing battery electrodes, comprising an electrode strip material comprising a foil and comprising an active material coating applied thereto and comprising a plurality of predetermined cutting points, a first planar vacuum belt for conveying the electrode strip material in a conveying direction, a second planar vacuum belt for conveying separated battery electrodes, separated from the first planar vacuum belt by a cutting gap, at least one laser for generating a first and second laser beam for severing the cutting points, and a controller for carrying out a method according to claim 1.

7. The device according to claim 6, wherein the first laser beam and/or the second laser beam can be moved by means of at least one polygon scanner, the at least one polygon scanner being arranged at an angle to the first vacuum belt.

8. The device according to claim 6, wherein the cutting gap extends obliquely to the conveying direction.

9. The device according to claim 6, wherein the first laser beam and/or the second laser beam can be moved by means of a number of sequentially connected polygon scanners.

10. A vehicle battery comprising a battery electrode which is produced using a method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] An embodiment of the invention is explained in more detail below with reference to the drawings, in which:

[0051] FIG. 1 is a plan view of a device for producing battery electrodes,

[0052] FIG. 2 is a plan view of a first method step in the production of the battery electrodes,

[0053] FIG. 3 is a plan view of a second method step in the production of the battery electrodes, and

[0054] FIG. 4 is a perspective view of a polygon scanning head for laser separation of the battery electrodes.

[0055] Corresponding parts and dimensions are always provided with the same reference signs in all figures.

DETAILED DESCRIPTION OF THE INVENTION

[0056] FIGS. 1 to 3 show a device 2 for producing battery electrodes 4 in simplified and schematic views. The battery electrodes 4 produced have an edge dimension of more than 100 mm, preferably between 300 and 600 mm, for example.

[0057] The device 2 has a first planar vacuum belt 6 and a second planar vacuum belt 8, which are spaced apart from one another by means of a recess 10. The recess 10 is arranged between the mutually facing end faces of the vacuum belts 6 and 8. In the region of the recess 10, a cutting gap 12 is provided which is shown by way of dot-dash lines in the figures.

[0058] By means of the vacuum belt 6, an electrode strip material 14 is conveyed to the cutting gap 12 in a conveying direction 16 with a continuous belt feed 18. The electrode strip material 14 is separated at predetermined cutting points 20 in the region of the cutting gap 12 to form the battery electrodes 4. The cutting points 20 are shown in the figures merely by way of example by means of dashed lines.

[0059] The battery electrodes 4 are transported by the vacuum belt 8 away from the cutting gap 12 in the conveying direction 16 with a continuous belt feed 22. The belt feeds 18 and 22 preferably have the same dimensions. The vacuum belts 6 and 8 each generate a negative pressure during operation, by means of which the electrode strip material 14 or the battery electrodes 4 are secured.

[0060] The strip-shaped or strip-like electrode strip material 14 is designed, for example, as a virtually endless roll material (electrode coil), and has an electrically conductive foil 24, for example a copper or aluminum foil, as a current conductor, and an active material coating 26 applied thereto.

[0061] The active material coating 26 is made from an electrode material, i.e. from an anode material or a cathode material. The electrode strip material 14 has, for example, a width of more than 100 mm, in particular between 300 and 600 mm, i.e. substantially the edge length of the battery electrodes 4, the length of the electrode strip material 14 being dimensioned so as to be substantially larger than its width or its height.

[0062] The device 2 has two laser optics or laser cutting elements 28, 30 for processing the electrode strip material 14, which are arranged to the side of the vacuum belt 6. The device 2 also has two optical sensor means 32, 34, for example in the form of cameras, which are arranged on the vacuum belt 6 so as to be spaced apart from one another in the conveying direction 18.

[0063] The sensor means 32 is arranged at the beginning of the vacuum belt 6, i.e spaced apart from the cutting gap 12, and the sensor means 34 is arranged at the end of the vacuum belt 6, i.e. in the region of the cutting gap 12. The sensor means 32 is provided in particular for web edge control, and is expediently arranged on the top and bottom of the vacuum belt 6. The sensor means 34 is provided in particular for detecting a transverse cut, by means of which the battery electrodes 4 are split or separated from the electrode strip material 14 along the cutting points 20.

[0064] A polygon scanning head 36 is provided for separating the battery electrodes 4, and is shown in detail in FIG. 4.

[0065] For example, the electrode strip material 14 has, in the longitudinal direction thereof, a non-coated or uncoated edge region of the foil 24, i.e. an edge-side foil region which is not provided with the active material coating 26. As can be seen relatively clearly in FIG. 1, the laser optics 28 and 30 each generate a laser beam 38 by means of which a conductor tab 40 for contacting the battery electrode 4 and rounded corner radii in the region of the cutting points 20 are cut from the edge region. The laser optics 28 cut an upper electrode region including the conductor tab 40 and radii, and the laser optics 30 cut a lower electrode region to a predetermined target length including radii. The material of the electrode strip material 14 which has been ablated in the course of laser cutting or laser processing is sucked off or removed through two suction devices 42 by means of an air or blowing stream.

[0066] The vacuum belts 6, 8 and the sensor means 32, 34 as well as the laser optics 30, 28 and the polygon scanning head 36 are connected by signals to a controller (not shown in more detail), i.e. to a control device or a control unit, and are controlled thereby.

[0067] The polygon scanning head 36 shown in detail in FIG. 4 has for example three lasers 44 in this embodiment. The lasers 44 each generate a laser beam 46, 46 during operation, with only one active laser 44 being shown by way of example in FIG. 4. The lasers 44 are designed, for example, as pulsed fiber lasers and have a wavelength in the infrared range (IR), for example.

[0068] The laser beam 46, 46 is directed to an associated polygon mirror as a polygon scanner 48, which reflects the laser beam 46, 46 in the direction of the electrode strip material 14 or the cutting point 20. The polygon scanner 48 is rotated during operation such that the laser beam 46, 46 is moved with a laser feed in an oblique or transverse direction, substantially perpendicularly to the conveying direction 16. The polygon scanners 48 have a laser feed of from 2 m/s to 1000 m/s, for example. As a result, the laser beams 46, 46 are moved particularly quickly over the cutting points 20, meaning the heat input, i.e. the thermal load on the electrode strip material 14, is particularly low.

[0069] In one conceivable embodiment, the laser beams 46, 46 of the lasers 44 are sequentially connected and guided over the cutting points 20 by means of the polygon scanner 48. This results in an increase in the cycle time and thus a particularly uniform production flow during the production of the battery electrodes 4.

[0070] The polygon scanners 48 are arranged so as to be inclined or tilted at an angle to the vacuum belt 6. The angles of inclination or tilt are adjusted to the continuous belt feed 18 of the vacuum belt 6 and the laser feed of the polygon scanner 48. This means that, in cooperation with the belt feed 18, the laser beams 46, 46 are guided in a straight line along the cutting points 20.

[0071] Preferably, the or each laser beam 46, 46 is guided, for the separation, several times over the relevant cutting point 20, the polygon scanning head 36 being suitably repositioned, in cycles, at a defined distance in the conveying direction 16 with each guidance, such that the laser beams 46, 46 always hit the same kerf or cutting notch at the cutting point of the electrode strip material 14.

[0072] The method according to the invention for producing the battery electrodes 4 is explained in more detail below with reference to FIGS. 2 and 3.

[0073] FIG. 2 shows a first method step of the method, in which the active material coating 26 is partially ablated at a cutting point 20 using first laser beams 46 of the laser 44 of the polygon scanning head 36 before the cutting point 20 reaches the cutting gap 12. This means that the laser beams 46 create a kerf or cutting notch in the active material coating 26 in the region of the particular cutting point 20. Preferably, approximately 40% to 99% of the active material coating 26 is ablated. Since the electrode strip material 14 is not completely severed here, but is only partially ablated, no cutting gap is required for the laser ablation during the first method step.

[0074] The laser beams 46 are guided over the cutting point 20 several times in succession during the first method step. There is therefore repeated guidance of the laser beams 46 over the cutting point 20. In a suitable embodiment, the laser beams 46 are moved over the cutting point 20 between 1 and 100 times.

[0075] FIG. 3 shows a second method step following the first method step, in which the active material coating 26 and the foil 24 of the electrode strip material 14 are completely severed at the cutting point 20 using second laser beams 46 when the cutting point 20 travels over the region of cutting gap 12. The cutting gap 12 is oriented obliquely to the conveying direction 16 of the vacuum belt 6, and is thus coordinated with the continuous belt feed 18 of the vacuum belt 6 and the laser feed of the second laser beams 46.

[0076] The laser beams 46 are guided over the cutting point 20 to be severed several times in succession during the second method step. The number of times that the guidance is repeated is preferably less than in the first method step. For example, the laser beams 46 are moved over the cutting point 20 between 1 and 20 times.

[0077] The repeated guidance during the first and/or second method step allows cold ablation of the electrode strip material 14, i.e. ablation with a particularly small heat input zone. As a result, the severing, i.e. the laser cut resulting in splitting or severing, can be achieved with a low or moderate laser power, which ensures a particularly high cutting edge quality of the separated battery electrodes 4.

[0078] The repeated guidance takes place substantially without interrupting the conveyance of the vacuum belts 6, 8. In other words, the battery electrodes 4 are separated without the vacuum belts 6, 8 being slowed down or stopped. The laser separation of the battery electrodes 4 thus takes place on-the-fly during continuous conveyance of the electrode strip material 14.

[0079] The claimed invention is not limited to the embodiment described above. Rather, other variants of the invention can also be derived therefrom by a person skilled in the art within the scope of the disclosed claims without departing from the subject matter of the claimed invention. In particular, all of the individual features described in connection with the embodiment can also be combined in other ways within the scope of the disclosed claims without departing from the subject matter of the claimed invention.

LIST OF REFERENCE SIGNS

[0080] 2 device [0081] 4 battery electrode [0082] 6, 8 vacuum belt [0083] 10 recess [0084] 12 cutting gap [0085] 14 electrode strip material [0086] 16 conveying direction [0087] 18 belt feed [0088] 20 cutting point [0089] 22 belt feed [0090] 24 foil [0091] 26 active material coating [0092] 28, 30 laser optics [0093] 32, 34 sensor means [0094] 36 polygon scanning head [0095] 38 laser beam [0096] 40 conductor tabs [0097] 42 suction device [0098] 44 laser [0099] 46, 46 laser beam [0100] 48 polygon scanner