DE102022128232A1 - Apparatus and method for producing battery electrodes - Google Patents

Abstract

Device (1) for producing battery electrodes (2), at least comprising a planar conveyor belt (3) with a support surface (4) for an electrode strip material (5), wherein the electrode strip material (5) can be conveyed by the conveyor belt (3) along a conveying direction (6), and a laser cutting device (7), at least comprising a 3D polygon scanner (8), via which a laser beam (9, 10) can be deflected towards the electrode strip material (5) arranged on the conveyor belt (3). A method for producing battery electrodes (2) is also specified.

Description

The invention relates to a device and a method for producing battery electrodes.

Electrically driven or powered motor vehicles, such as electric or hybrid vehicles, typically have an electric motor as a drive machine, which is coupled to an internal (high-voltage) electrical energy storage device in the vehicle to supply electrical energy. Such energy storage devices are designed, for example, in the form of (vehicle) batteries.

An electrochemical battery is understood here to be a so-called secondary battery of the motor vehicle, in which a used chemical energy can be restored by means of an electrical charging process. Such batteries are designed in particular as electrochemical accumulators, for example as lithium-ion accumulators. In order to generate or provide a sufficiently high operating voltage, such batteries typically have several individual battery cells which are connected in a modular manner.

Batteries of the type mentioned have at least one cathode and one anode as well as a separator and an electrolyte on a battery cell level. The electrodes, i.e. the anode and the cathode, are made from at least one respective (electrode) active material. In particular, the active material is applied as a coating to a carrier material, e.g. a metallic foil, in particular on both sides.

For example, extrusion processes are possible for the production of batteries, in which the battery electrodes of the battery cells are made from a plastic mass. The electrode pastes are applied as an active material coating to a respective current conductor, in particular to a copper or aluminum foil. This produces a strip or band-shaped electrode tape material, which is assembled and further processed in particular as endless material or roll material, as a so-called electrode coil. The endless electrode tape material has a length that is significantly larger than its width or thickness or height.

A number of battery electrodes are then produced from the electrode strip material. To do this, the electrode strip material is separated, i.e. severed or cut to length, at predetermined interfaces. The interfaces run particularly along the width, i.e. across the "endless" length of the electrode strip material.

The battery electrodes are separated, for example, mechanically, in particular by means of a punching process, or by means of a laser beam.

In the case of mechanical separation, it is possible, for example, for the battery electrodes to be separated from the electrode strip material with a full cut, or for the battery electrodes to be separated in a two-part separation process, with a notching of an upper and lower edge of the interface and with a subsequent transverse cut for complete severing.

In laser separation, a laser beam is guided over the interface, for example using a (galvo) scanner. The laser beam ablates the active material coating and the film. “Ablation” or “ablation” refers in particular to laser ablation, in which a laser beam locally heats a material in such a way that a plasma is created and the material is removed by the heating. The laser beam is focused on the electrode strip material, whereby the material is removed in a heat input zone or a heat-affected zone, and the interface is thus severed. In the known processes, bumps or burrs regularly arise in the cutting gap to be created, which can lead to errors or malfunctions when using the electrodes produced in this way (e.g. short circuits, fine circuits, shorter service life of the battery cell, loss of capacity of the battery cell due to thermal or mechanical influences on the electrodes).

The electrode strip material is guided to a processing or cutting area for separation, for example by means of a conveyor device along its length. The conveyor device is then stopped so that the electrode strip material is separated mechanically or by laser at the respective interface when the conveyor device is at a standstill. The conveyor device is then started again, and the separated battery electrode is moved away from the cutting area and a new interface of the electrode strip material is moved towards the cutting area.

The foil or the current conductor of the electrode strip material is comparatively thin and has a foil thickness of only about 6 to 12 µm (micrometers). By regularly or periodically, i.e. synchronized stopping and starting of the conveyor in the During the separation process, acceleration forces act on the electrode strip material, which can lead to damage to the film and/or the active material. In order to reduce the cycle time and ensure economical production, it is necessary to reduce the acceleration and deceleration speeds of the conveyor system, which adversely affects the time required to produce the battery electrodes.

Until now, laser separation required the conveyor system to be brought to a standstill, as typical scanners for moving the laser beam along the cutting point have comparatively low laser feed speeds of around 6 m/s (meters per second) with a mirror diameter of 50 mm (millimeters). Due to the slow laser feed speeds of known scanners, the conveyor system must be stopped during separation in order to achieve a high cutting edge quality on the one hand, and to avoid damaging or destroying the conveyor system on the other. The cutting area is usually designed as a cutting or cutting gap with suction on both sides for the ablated material.

To create more powerful batteries or battery cells, battery electrodes with relatively large dimensions are particularly desirable. Therefore, electrode strip materials must be separated with an increasingly larger width, and thus with longer interfaces. This means that during laser separation, it is necessary to cover a larger processing area with the scanner. This requires a larger spot diameter or focus area of the laser beam, and thus a correspondingly larger heat input zone, which means that more energy is introduced into the active material coating. However, this adversely reduces the cutting edge quality of the battery electrode.

Furthermore, particularly with so-called on-the-fly cuts (i.e. with continuous conveyance of the electrode strip material), a larger cutting gap, in particular a larger clear width of the cutting gap, for example up to 100 µm along the length of the electrode strip material, is necessary, which gives rise to the problem of bending of the electrode strip material or the interface in the area of the cutting gap. Due to the bending, the active material coating and the film are no longer in the focus area of the laser beam, which further reduces the cutting edge quality of the individual battery electrodes. On the other hand, such bending represents a high mechanical load for the electrode strip material, which can cause damage or destruction to the electrode strip material.

With the known laser separation processes (notching or full cut) and cutting speeds between 2 and 6 m/s, heat-affected zones are created on the separated battery electrode, which extend from the cutting gap and along a direction transverse to the cutting gap over an area of approx. 100 µm (anode) or approx. 150 µm (cathode). Furthermore, bulges (i.e. local elevations in the thickness direction of the battery electrode) of the order of 20 µm and burrs (i.e. local elevations in the longitudinal direction of the battery electrode) of 20 µm are created.

Because the laser cut is carried out transversely or at right angles to the length of the electrode strip material on a moving support surface of a conveyor, which in typical applications is drum-shaped, it is necessary to track the laser or the focal point of the laser beam in the X (length), Y (width) and Z (thickness) directions, for example using a combination of polygon or galvo scanners. The known methods are currently not feasible or realizable, particularly when producing larger battery electrodes, because the laser beam cannot be adjusted quickly enough along the Z direction using a galvo scanner while the wheel or drum is rotating.

From the EN 10 2017 216 143 A1 A method for producing an electrode stack is known.

From the EN 10 2018 219 619 A1 A method for separating electrodes by means of a laser cutting device is known.

From the EN 10 2019 206 124 A1 A method for separating electrodes by punching is known.

The object of the present invention is to at least partially solve the problems mentioned with reference to the prior art and in particular to provide a particularly suitable device and a method for producing battery electrodes. In particular, a production flow that is as uniform as possible is to be realized, in which the mechanical and thermal stress on the electrode strip material is reduced and the highest possible cutting edge quality of the battery electrodes is ensured.

A device with the features according to claim 1 contributes to the solution of these tasks. Advantageous further developments are the subject of of the dependent patent claims. The features listed individually in the patent claims can be combined with one another in a technologically meaningful manner and can be supplemented by explanatory facts from the description and/or details from the figures, whereby further embodiments of the invention are shown.

The device according to the invention is suitable and designed for producing battery electrodes, in particular for vehicle batteries.

The device comprises at least one planar conveyor belt and (at least) one laser cutting device. The conveyor belt has a support surface for an (endless) electrode strip material, wherein the electrode strip material can be conveyed by the conveyor belt along a conveying direction. The laser cutting device comprises at least one 3D polygon scanner, via which a laser beam can be deflected towards the electrode strip material arranged on the conveyor belt.

In particular, the device is used to separate, i.e. separate or cut to length, an endless, i.e. in particular band- or strip-shaped electrode tape material, in particular in the form of a roll material (electrode coil, electrode winding), in particular with an electrically conductive film as a current conductor and with an active material coating applied thereto, at predetermined interfaces to form a number of battery electrodes. The term "endless" here means in particular that the electrode tape material is provided with a dimension that is many times larger than the dimension of the battery electrode itself or that a large number of battery electrodes can be produced from it.

The support surface of the conveyor belt, at least in the area in which the laser beam acts on the electrode strip material, is in particular planar or flat, i.e. not curved, in particular as a vacuum belt. The electrode strip material is conveyed along a conveying direction to the laser cutting device via the conveyor belt. The conveying takes place in a planar manner, i.e. essentially in a horizontal plane. The vacuum belt suitably generates a negative pressure by means of which the electrode strip material is fixed or held on the support surface during conveying.

The cutting gap to be created on the electrode strip material is stationary relative to the conveyor belt, which means that the cutting gap does not wander or move relative to the conveyor belt when the electrode strip material is conveyed.

The laser cutting device as a whole is arranged in a stationary manner, in particular, so that the electrode strip material is conveyed past the laser cutting device, in particular continuously. In particular, the components of the laser cutting device, e.g. the 3D polygon scanner and/or a galvo scanner, are also arranged in a stationary manner, whereby a rotary movement of the respective scanner is possible, but a transverse movement of the scanner is not.

In a 3D polygon scanner, a laser beam is deflected twice by the scanner, resulting in particularly good beam control accuracy and good beam quality of the laser beam. The 3D polygon scanner therefore has at least one pair of reflection surfaces, with a laser beam first striking a first reflection surface and then being deflected to the second reflection surface. The reflection surfaces are arranged on a rotating body, i.e. they are only moved together. In the present method of laser separation of battery electrodes, the Rayleigh length of the laser beam used is comparatively short, so that good control of the laser beam is particularly important for the quality of the cutting gap produced.

In contrast, with a 2D polygon scanner, a laser beam is only deflected once. With a polygon scanner, a body that has a number of reflective surfaces rotates around an axis of rotation (i.e. only in one direction), so that a laser beam is deflected one after the other by the individual reflective surfaces.

In a galvo scanner, a reflection surface oscillates (back and forth, not rotating) around a rotation axis.

In particular, the 3D polygon scanner is shaped such that the laser beam, starting from a beam source (for the laser beam), strikes a first reflection surface of the 3D polygon scanner and can be deflected from there onto a second reflection surface of the 3D polygon scanner, which is arranged in a fixed position relative to the first reflection surface.

In particular, the 3D polygon scanner has a body on which the reflection surfaces are arranged together. In particular, the body has a (second) axis of rotation about which the body and thus the reflection surfaces rotate. In particular, the body is designed as a double cone, wherein a plurality of first reflection surfaces are arranged on a first conical surface and a plurality of second reflection surfaces are arranged on a second conical surface. The (second) axis of rotation axis is in particular arranged concentrically to the cone axes, whereby the cone surfaces are inclined towards each other.

In particular, the laser cutting device comprises a galvo scanner, wherein the galvo scanner and the 3D polygon scanner are arranged relative to one another and to the beam source in such a way that a laser beam starting from the beam source can be deflected via the first reflection surface to the second reflection surface and from there to the galvo scanner or is deflected during operation of the laser cutting device.

In particular, the electrode strip material arranged on the support surface can be moved by the conveyor belt relative to the laser cutting device along the conveying direction, wherein a cutting gap to be created on the electrode strip material by the laser cutting device extends along a first direction running perpendicular to the conveying direction (i.e. along the width of the electrode strip material). A focus position or a focus point of the laser beam can be moved on the electrode strip material by the galvo scanner at least or exclusively along the conveying direction (alternatively along the first direction). The focus position or a focus point of the laser beam can be moved by the 3D polygon scanner at least or exclusively along the first direction (i.e. along the width of the electrode strip material; alternatively along the conveying direction).

In particular, a first axis of rotation of the galvo scanner extends parallel to the support surface. One (or the only) reflection surface of the galvo scanner rotates or oscillates in particular about the first axis of rotation.

In particular, a second axis of rotation of the 3D polygon scanner extends perpendicular to the support surface.

An arrangement of the respective axis of rotation that is inclined relative to the support surface or the cutting gap (inclined here means a smallest angle between the axis of rotation and the support surface or the axis of rotation and the cutting gap is between zero - zero excluded - and 90 - 90 excluded - angular degrees) can be avoided in particular here, so that the short Rayleigh length that is usual here cannot have a significant influence on the quality of the cutting gap (due to the easily controllable focus position of the laser beam, especially in the thickness direction of the electrode strip material.

In particular, the 3D polygon scanner has a plurality of pairs of a first reflection surface and a second reflection surface, wherein the pairs are arranged next to one another along a circumferential direction about the second axis of rotation.

A method for producing battery electrodes is also proposed. In particular, the method is carried out using the device described.

The method is carried out in particular with a device that comprises at least one planar conveyor belt and a laser cutting device. The conveyor belt has a support surface for an endless electrode strip material, wherein the electrode strip material can be conveyed by the conveyor belt along a conveying direction. The laser cutting device in particular comprises at least one 3D polygon scanner, via which a laser beam can be deflected towards the electrode strip material arranged on the conveyor belt.

1. a) Bereitstellen der Vorrichtung und Anordnen des Elektrodenbandmaterials auf der Auflagefläche des Förderbands;
2. b) Fördern des Elektrodenbandmaterials entlang der Förderrichtung; und dabei
3. c) Beaufschlagen des Elektrodenbandmaterials an einem zu erzeugenden Schneidspalt mit mindestens einem Laserstrahl.

The procedure comprises at least the following steps:

1. a) providing the device and arranging the electrode strip material on the support surface of the conveyor belt;
2. b) conveying the electrode strip material along the conveying direction; and
3. c) Exposing the electrode strip material to a cutting gap to be created with at least one laser beam.

The above (non-exhaustive) classification of the process steps into a) to c) is primarily intended to serve only as a means of differentiation and does not force a sequence and/or dependency. The frequency of the process steps, e.g. during setup and/or operation of the device, can also vary. It is also possible for process steps to at least partially overlap one another in time. It is particularly preferred that process steps b) and c) take place at least partially simultaneously. In particular, step c) can be conditional and may only be carried out if step b) is carried out. In particular, step c) is carried out several times (namely by several laser devices or with the simultaneous use of several laser beams or several laser sources). In particular, steps a) to c) are carried out in the order given.

In particular, a first speed of the laser beam along the cutting gap to be created is at least 20 m/s [meters per second], preferably at least 30 m/s, particularly preferably at least 100 m/s. In particular, the first speed can be at most 1,000 m/s, preferably at most 150 m/s.

In particular, the high speeds possible here can reduce a heat-affected zone on the separated electrode strip material (i.e. the electrode). In particular, in step c), the material of the electrode strip material evaporates almost exclusively (and does not melt), so that it can be completely removed from the area of the cutting gap.

In particular, a heat-affected zone can be created which extends from the cutting gap and along a direction transverse to the cutting gap over a region of at most 50 µm, in particular at most 20 µm, preferably at most 10 µm. In particular, the formation of a heat-affected zone on the finished electrode strip material can be completely prevented.

In particular, in the area of the cutting gap created, bulges (i.e. local elevations in the thickness direction of the battery electrode) have a maximum extension of 5 µm compared to the otherwise flat surface of the electrode strip material. In particular, bulges can be completely avoided.

In particular, in the region of the cutting gap produced, burrs (i.e. local elevations in the longitudinal direction of the battery electrode) have an extension of at most 15 µm, preferably of at most 10 µm or even at most 5 µm, compared to an averaged straight course of the cutting edge of the cutting gap.

In particular, the mentioned qualities of the cutting gap can be achieved with carrier materials or metallic foils coated with active material, in particular with electrode strip material (with active material) that is used for lithium-ion battery cells with liquid electrolyte or with solid electrolyte (so-called all-solid-state battery cells, namely with active material, separator material and electrolyte).

In particular, a second speed of the conveyor belt relative to the laser cutting device is at least 40 m/min [meters per minute], preferably at least 60 m/min. In particular, the second speed is at most 100 m/min.

In particular, several laser cutting devices can be arranged along the conveying direction for successively applying a laser beam to a cutting gap to be created. In such a case, in a first step, the electrode strip material can be exposed to a first laser beam and in a subsequent second step, the electrode strip material can be exposed to a second laser beam. The electrode strip material can initially be partially severed in the area of the cutting gap and then completely severed later. The electrode strip material can in particular cool down between the steps so that the thermal load in the area of the cutting gap is comparatively low. This subsequently has an advantageous effect on the cutting edge quality of the battery electrodes.

In particular, after the cutting gap has been created (or after the electrode strip material has been completely severed), a so-called cleaning scan can be carried out, which can be used to remove any remaining build-up. In particular, a slight bevel can be created on the cutting edge. In particular, the cleaning scans increase the cycle time of the process (measured in terms of the time required to completely cut through the electrode strip material) by a maximum of 10%.

Due to the planar conveyor belt, tracking of the laser beam or the focus position of the laser beam along a Z-direction, i.e. perpendicular to the surface of the electrode strip material, is essentially not necessary or at least significantly reduced.

The interfaces or cutting gaps run in particular transversely, i.e. transversely or perpendicularly, to the longitudinal direction or length of the electrode strip material or to the conveying direction of the conveyor belt. The electrode strip material has, for example, a width of more than 100 mm [millimeters], in particular between 300 and 600 mm. This means that the individual battery electrodes in particular have an edge dimension of more than 100 mm, preferably between 300 and 600 mm.

The electrode strip material has, in particular along its longitudinal direction, a non-coated or uncoated edge region of the carrier material or the film, i.e. an edge region of the film which is not provided with the active material coating. From this edge region, in particular during the manufacture of the battery electrodes, an associated conductor flag is produced for electrically contacting the battery electrode arranged in the battery cell.

In particular, the laser beam of a laser device is guided several times in succession over the cutting gap to be created during step c). This means that during step c) the cutting gap or the interface is passed over several times with the laser beam. For example, the laser beam is moved between one and 100 times over the interface.

The multiple passes are preferably carried out with the highest possible first speed, i.e. with the largest possible laser feed. This makes it possible to create the cutting gap or the kerf or cutting notch with a particularly low or moderate laser power, which reduces the heat input or the heat input zone in the area of the kerf or cutting notch. This makes it possible to achieve better edge qualities of the cutting gap and thus of the battery electrode edge.

In particular, the rapid multiple passes make it possible to create a particularly narrow cutting gap, i.e. a cutting gap with a reduced clear width. This advantageously reduces the mechanical stress on the electrode strip material in the area of the cutting gap. In particular, this ensures that the electrode strip material or the interface in the area of the cutting gap does not sag as much as possible, which keeps the electrode strip material in the plane of the focal point of the laser beam. This means that the narrowest possible cutting gaps can also be created for larger battery electrode dimensions, i.e. for larger widths of the electrode strip material.

The multiple passes enable a so-called cold ablation of the electrode strip material, i.e. an ablation with a particularly small heat input zone.

In particular, the ablated material of the electrode strip material is sucked off during step c), i.e. removed by means of an air or blowing stream. During the multiple passes, only a comparatively small amount of ablated material is produced, which makes particularly simple and reliable suction possible. In particular, this enables a particularly high volume flow with a reduced flow diameter. This further improves the quality of the battery electrodes produced.

In particular, steps b) and c) take place without interrupting and/or without slowing down or accelerating the conveyor belt. The laser separation of the battery electrodes is thus carried out "on the fly", i.e. during continuous conveyance of the electrode strip material. The conveyance of the electrode strip material is therefore not interrupted or slowed down. This essentially completely avoids acceleration forces on the electrode strip material. This ensures a particularly uniform and time-reduced production flow when manufacturing the battery electrodes.

The laser is designed in particular as a pulsed or continuous wave (cw) fiber laser. The fiber laser has a wavelength suitable for ablating the electrode strip material, preferably a wavelength in the green or infrared range (IR), for example around 530 nm or 1000 nm [nanometers]. The laser has, for example, a laser output in the kilowatt range (kW).

In particular, the laser device additionally comprises a focusing device, in particular a so-called and basically known F-theta lens. This lens, also known as a plane field lens, is used in particular in connection with galvo scanners in order to keep a laser beam diameter in the area of the focus position of the laser beam as small and constant as possible over the entire processing plane (i.e. along the cutting gap to be created). The F-theta lens is arranged in particular between the scanner(s) and the electrode strip material.

In particular, the device comprises one or more (in particular optical) sensors, via which a position of the electrode strip material relative to the laser device can be detected. Furthermore, the at least one sensor serves to place the strip material on the conveyor belt in such a way that there is in particular a gap in the conveyor belt below the cutting gap to be created, so that the conveyor belt is not damaged by the laser beam.

In particular, at least one data processing system is provided which has means which are suitably equipped, configured or programmed to carry out the method or which carry out the method. The means is or are particularly suitably designed to control the components of the device and to record and evaluate measured values.

The means include, for example, a processor and a memory in which instructions to be executed by the processor are stored, as well as data lines or transmission devices that enable a transmission of instructions, measured values, e.g. from sensors, data or the like between the elements mentioned.

The “means” may in particular comprise one or more of the following components: controller(s), microcontroller, data storage, data connection, display devices (such as a display), counter or timer, at least one other sensor, an energy source, etc.

A computer program is further proposed, comprising instructions which, when the program is executed by a computer, cause the computer to carry out the described method or the steps of the described method.

A computer-readable storage medium is also proposed, comprising instructions which, when executed by a computer, cause the computer to carry out the described method or the steps of the described method.

The statements regarding the device are particularly transferable to the method, the data processing system and/or the computer-implemented method (i.e. the computer program and the computer-readable storage medium) and vice versa.

In particular, a battery electrode produced using the device or the method is used in a battery cell and/or in a vehicle battery. The method according to the invention enables a uniform production flow in the manufacture of the battery electrode, in which the mechanical and thermal stress on the electrode strip material is reduced. The battery electrode therefore has a particularly high cutting edge quality, which has an advantageous effect on the quality and performance of the battery cell equipped with it.

The use of indefinite articles ("a", "an", "an" and "another"), particularly in the patent claims and the description reflecting them, is to be understood as such and not as a number. Terms or components introduced accordingly are therefore to be understood as being present at least once and, in particular, can also be present multiple times.

As a precaution, it should be noted that the numerals used here ("first", "second", ...) primarily serve (only) to distinguish between several similar objects, sizes or processes, and in particular do not necessarily specify a dependency and/or sequence of these objects, sizes or processes. If a dependency and/or sequence is required, this is explicitly stated here or it is obvious to the person skilled in the art when studying the specifically described design. If a component can occur multiple times ("at least one"), the description of one of these components can apply equally to all or part of the majority of these components, but this is not mandatory.

• 1: eine erste Ausführungsvariante einer Vorrichtung in einer perspektivischen Ansicht;
• 2: die Bearbeitung eines Schneidspalts in verschiedenen Ansichten; und
• 3: eine zweite Ausführungsvariante einer Vorrichtung in einer perspektivischen Ansicht.

The invention and the technical environment are explained in more detail below with reference to the attached figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments given. In particular, it should be noted that the figures and in particular the size relationships shown are only schematic. They show:

• 1 : a first embodiment of a device in a perspective view;
• 2 : the machining of a cutting gap in different views; and
• 3 : a second embodiment of a device in a perspective view.

1 shows a first embodiment of a device 1 in a perspective view.

The device 1 comprises a planar conveyor belt 3 and a laser cutting device 7. The conveyor belt 3 has a support surface 4 for an endless electrode strip material 5, wherein the electrode strip material 5 can be conveyed by the conveyor belt 3 along a conveying direction 6. The laser cutting device 7 comprises a 3D polygon scanner 8, via which a laser beam 9 can be deflected towards the electrode strip material 5 arranged on the conveyor belt 3.

The laser cutting device 7 comprises a galvo scanner 14, wherein the galvo scanner 14 and the 3D polygon scanner 8 are arranged relative to one another and to the beam source 11 such that, during operation of the laser cutting device 7, a laser beam 9 is redirected from the beam source 11 via a first reflection surface 12 of the 3D polygon scanner 8 to a second reflection surface 13 and from there to a third reflection surface 24 of the galvo scanner 14.

In the galvo scanner 14, the third reflection surface 24 oscillates about a first axis of rotation 18.

The laser cutting device 7 as a whole is arranged in a stationary manner so that the electrode strip material 5 is continuously conveyed past the laser cutting device 7. The components of the laser cutting device 7, i.e. the 3D polygon scanner 8 and the galvo scanner 14, are arranged in a stationary manner, whereby a rotary movement of the respective scanner 8, 14 is possible, but a transverse movement of the scanner 8, 14 is not.

The 3D polygon scanner 8 is shaped so that the laser beam 9 originates from a beam source 11 for the laser beam 9 strikes a first reflection surface 12 of the 3D polygon scanner 8 and is deflected from there onto a second reflection surface 13 of the 3D polygon scanner 8, which is arranged stationary relative to the first reflection surface 12.

The 3D polygon scanner 8 has a body 21 on which the reflection surfaces 12, 13 are arranged together. The body has a second axis of rotation 19 around which the body 21 and thus the reflection surfaces 12, 13 rotate. The body 21 is designed as a double cone, with a plurality of first reflection surfaces 12 being arranged on a first conical surface 22 and a plurality of second reflection surfaces 13 being arranged on a second conical surface 23. The second axis of rotation 19 is arranged concentrically to the conical axes or conical surfaces 22, 23, with the conical surfaces 22, 23 being inclined towards one another.

The 3D polygon scanner 8 has a plurality of pairs of a first reflection surface 12 and a second reflection surface 13, wherein the pairs are arranged next to one another along a circumferential direction 20 about the second axis of rotation 19.

The first rotation axis 18 of the galvo scanner 14 extends parallel to the support surface 4. The third reflection surface 24 of the galvo scanner 14 oscillates around the first rotation axis 18.

The second rotation axis 19 of the 3D polygon scanner 8 extends perpendicular to the support surface 4.

An arrangement of the respective rotation axes 18, 19 inclined relative to the support surface 4 or the cutting gap 15 (inclined here means a smallest angle between the rotation axes 18, 19 and the support surface 4 or the rotation axes 18, 19 and the cutting gap 15 is between zero - zero excluded - and 90 - 90 excluded - angular degrees) can be avoided here, so that the short Rayleigh length that is usual here cannot have a significant influence on the quality of the cutting gap 15 (due to the easily controllable focus position 17 of the laser beam 9, in particular in the thickness direction of the electrode strip material 5).

The laser cutting device 7 additionally comprises a focusing device 32, which is arranged between the scanners 8, 14 and the electrode strip material 5.

The electrode strip material 5 arranged on the support surface 4 can be moved by the conveyor belt 3 relative to the laser cutting device 7 along the conveying direction 6, wherein a cutting gap 15 to be created on the electrode strip material 5 by the laser cutting device 7 extends along a first direction 16 running perpendicular to the conveying direction 6 (i.e. along the width of the electrode strip material 5). A focus position 17 or a focus point of the laser beam 9 can be moved on the electrode strip material 5 by the galvo scanner 14 exclusively along the conveying direction 6. The focus position 17 of the laser beam 9 can be moved by the 3D polygon scanner 8 exclusively along the first direction 16.

The electrode strip material 5 has a non-coated or uncoated edge region 29 of the carrier material or the film along its longitudinal direction (parallel to the conveying direction 6), i.e. a film region on the edge that is not provided with the active material coating. In the course of producing the battery electrodes 2, an associated conductor flag 30 is produced from this edge region 29 for electrically contacting the battery electrode 2 arranged in the battery cell.

The ablated material of the electrode strip material 5 is sucked off during step c), i.e. during the application of the laser beam 9 to the electrode strip material 5 at a cutting gap 15 to be created, i.e. removed by means of an air or blowing stream 31.

2 shows the machining of a cutting gap 15 in different views a) to d). Please refer to the explanations for 1 reference is made.

In 2a) the cutting gap 15 is shown in a perspective view. Raises 26 can be seen on the cutting edges 28 of the electrode strip material 5. A heat-affected zone 25 can be created on the battery electrode 2 produced, which extends from the cutting gap 15 and along a direction (parallel to the conveying direction 6) transverse to the cutting gap 15 over an area of at most 50 µm. In particular, the formation of a heat-affected zone 25 on the finished electrode strip material 5 can be completely prevented.

In 2 B) the execution of a cleaning scan is shown. For example, after the cutting gap 15 has been created (or after the electrode strip material 5 has been completely severed), a so-called cleaning scan can be carried out, by means of which any remaining projections 26 can be removed. In particular, a slight bevel 27 can be created on the cutting edge 28.

In the area of the cutting gap 15 created by the impact of the laser beam 9, the usual bulges 26 (i.e. local Increases in the thickness direction of the battery electrode 2) can be completely avoided or removed by the cleaning scan.

The bevel 27 created after performing the cleaning scan is in the 2c )in another perspective view. In the 2d ), the course of the cutting edges 28 or the shape of the cutting gap 15 is shown in a sectional view along the first direction 16.

3 shows a second embodiment of a device 1 in a perspective view. The explanations regarding the 1 and 2 reference is made.

Here, several laser cutting devices 7 are arranged along the conveying direction 6 for successively applying several laser beams 9, 10 to a cutting gap 15 to be created. In a first step, the electrode strip material 5 is exposed to a first laser beam 9 and in a subsequent second step it is exposed to a second laser beam 10. The electrode strip material 5 can initially be partially severed in the area of the cutting gap 15 and then completely severed later. The electrode strip material 5 can cool down between the steps so that the thermal load in the area of the cutting gap 15 is comparatively low. This subsequently has an advantageous effect on the cutting edge quality of the battery electrodes 2.

The device 1 comprises several (in particular optical) sensors 33, via which a position of the electrode strip material 5 relative to the laser cutting device 7 can be detected. The sensors 33 also serve to place the electrode strip material 5 on the conveyor belt 3 in such a way that a gap 34 is present in the conveyor belt 3 below the cutting gap 15 to be created, so that the conveyor belt 3 is not damaged by the laser beam 9, 10.

For the calibration of the laser cutting device 7, for example, at least three sensors 33 are required, two for determining the position of the electrode strip material 5 relative to the conveying direction 6 and one sensor 33 for determining the position of the electrode strip material 5 relative to the first direction 16.

The device 1 comprises a system 35 for data processing, which has means that are suitably equipped, configured or programmed for carrying out the method or that carry out the method. The means is or are designed in particular for controlling the components of the device 1, e.g. the conveyor belt 3, the laser cutting devices 7, the beam sources 11, the adjustment of the air flow 31, etc., and for recording and evaluating measured values from the sensors 33.

List of reference symbols

1

contraption

2

Battery electrode

3

Conveyor belt

4

Support surface

5

Electrode tape material

6

Conveying direction

7

Laser cutting device

8th

3D polygon scanner

9

first laser beam

10

second laser beam

11

Beam source

12

first reflection surface

13

second reflection surface

14

Galvo scanner

15

Cutting gap

16

first direction

17

Focus position

18

first axis of rotation

19

second axis of rotation

20

Circumferential direction

21

Body

22

first conical surface

23

second conical surface

24

third reflection surface

25

Heat affected zone

26

Throw-up

27

chamfer

28

Cutting edge

29

Edge area

30

Conductor flags

31

Airflow

32

Focusing device

33

sensor

34

gap

35

system

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• DE 102017216143 A1 [0017]
• DE 102018219619 A1 [0018]
• DE 102019206124 A1 [0019]

Claims (10)

Device (1) for producing battery electrodes (2), at least comprising a planar conveyor belt (3) with a support surface (4) for an electrode strip material (5), wherein the electrode strip material (5) can be conveyed by the conveyor belt (3) along a conveying direction (6), and a laser cutting device (7), at least comprising a 3D polygon scanner (8), via which a laser beam (9, 10) can be deflected towards the electrode strip material (5) arranged on the conveyor belt (3). Device (1) according to Patent claim 1 , wherein the 3D polygon scanner (8) is shaped such that the laser beam (9, 10) originating from a beam source (11) strikes a first reflection surface (12) of the 3D polygon scanner (8) and can be deflected from there onto a second reflection surface (13) of the 3D polygon scanner (8), which is arranged in a fixed position relative to the first reflection surface (12). Device (1) according to Patent claim 2 , wherein the laser cutting device (7) comprises a galvo scanner (14), wherein the galvo scanner (14) and the 3D polygon scanner (8) are arranged relative to one another and to the beam source (11) such that the laser beam (9, 10) can be deflected from the beam source (11) via the first reflection surface (12) to the second reflection surface (13) and from there to the galvo scanner (14). Device (1) according to Patent claim 3 , wherein the electrode strip material (5) arranged on the support surface (4) can be moved by the conveyor belt (3) relative to the laser cutting device (7) along the conveying direction (6), wherein a cutting gap (15) to be created on the electrode strip material (5) by the laser cutting device (7) extends along a first direction (16) running perpendicular to the conveying direction (6); wherein a focus position (17) of the laser beam (9, 10) on the electrode strip material (5) can be moved by the galvo scanner (14) at least or exclusively along the conveying direction (6); wherein the focus position (17) can be moved by the 3D polygon scanner (8) at least or exclusively along the first direction (16). Device (1) according to one of the preceding Patent claims 3 and 4 , wherein a first axis of rotation (18) of the galvo scanner (14) extends parallel to the support surface (4). Device (1) according to one of the preceding claims, wherein a second axis of rotation (19) of the 3D polygon scanner (8) extends perpendicular to the support surface (4). Device (1) according to Patent claim 6 , wherein the 3D polygon scanner (8) has a plurality of pairs of a first reflection surface (12) and a second reflection surface (13), wherein the pairs are arranged next to one another along a circumferential direction (20) about the second axis of rotation (19). Method for producing battery electrodes (2) with a device (1) according to one of the preceding claims, wherein the method comprises at least the following steps: a) providing the device (1) and arranging the electrode strip material (5) on the support surface (4) of the conveyor belt (3); b) conveying the electrode strip material (5) along the conveying direction (6); and in the process c) applying at least one laser beam (9, 10) to the electrode strip material (5) at a cutting gap (15) to be created. Procedure according to Patent claim 8 , wherein a first speed of the laser beam (9, 10) along the cutting gap (15) to be generated is at least 20 m/s. Method according to one of the preceding Patent claims 8 and 9 , wherein a second speed of the conveyor belt (3) relative to the laser cutting device (7) is at least 40 m/min.

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