TRANSPORT DEVICE WITH LOW-TENSION FOIL GUIDING FOR THE PRODUCTION OF BATTERIES

Abstract

Proposed is a transport device for transporting a carrier in the form of a foil for producing electrodes for energy accumulators, in particular electrodes for lithium-ion batteries, having at least two rollers on which the carrier is able to be borne, and of which at least one of the rollers is provided with a drive so as to, by rotation of the driven roller, move the carrier along the longitudinal extent thereof, and transport the carrier from roller to roller. Provided for improving the manufacturing quality is a drive device for generating an additional force which facilitates transport and which for generating an alternating magnetic field has an alternating field generator that generates a temporally changing magnetic field so as to induce eddy currents in the carrier, and so as to exert a Lorentz force on the charges flowing in the carrier as a consequence of the eddy currents.

Claims

1. A transport device for transporting a carrier in the form of a foil for producing electrodes for energy accumulators, comprising at least two rollers on which the carrier is able to be borne, and of which at least one of the rollers is provided with a drive so as to, by rotating the driven roller, move the carrier along the longitudinal extent thereof and to transport the carrier from roller to roller, further comprising a drive device for generating an additional force that facilitates the transport, wherein the drive device generates an alternating magnetic field and has an alternating field generator which for inducing eddy currents in the carrier generates a temporally changing magnetic field, in order to exert a Lorentz force on the charges flowing in the carrier as a result of the eddy currents.

2. The transport device according to claim 1, wherein the alternating field generator is integrated in one of the rollers, and is disposed such that the latter is not in contact with the carrier during transport.

3. The transport device according to claim 1, further comprising an orienting device for orienting graphite particles for an electrode in lithium-ion batteries in a coating with which the carrier is provided, said orienting device generating a magnetic field that is variable in terms of time and/or location.

4. The transport device according to claim 3, wherein the orienting device is configured for generating in the carrier eddy currents in the carrier plane, the preferred directions of said eddy currents running in particular transversely to the transport direction.

5. The transport device according to claim 1, wherein the alternating field generator is integrated in one of the rollers.

6. The transport device according to claim 1, wherein the alternating field generator is configured as a rotor, at least two permanent magnets being disposed along the circumference of said rotor.

7. The transport device according to claim 6, wherein the permanent magnets are disposed in an Halbach array along the circumference such that the fields in the interior of the permanent magnets are in each case oriented so as to be tangential or radial in relation to the path of rotation in the rotation plane.

8. The transport device according to claim 6, wherein the rotor has a rotor drive device including a motor with a timing belt.

9. The transport device according to claim 8, wherein the rotor drive device is configured for varying the rotating speed of the rotor and for adapting said rotating speed to the transport speed of the carrier at a specific ratio, in particular for adapting said rotating speed such that a defined force acts on the carrier.

10. The transport device according to claim 6, wherein the rotor is mounted on a static shaft.

11. The transport device according to claim 10, wherein the rotor is mounted on the static shaft by way of at least one roller bearing.

12. The transport device according to claim 1, wherein the alternating field generator is configured as a stator of a linear motor which is disposed relative to the transport section of the carrier such that the carrier is driven as a slider.

13. The transport device according to claim 12, wherein the stator of the linear motor has at least three coils which are disposed along the transport section of the carrier and through which a mutually phase-delayed alternating current flows.

14. The transport device according to claim 13, wherein the coils are incorporated in the grooves of an iron core and/or of a laminated sheet package.

15. The transport device according to claim 1, wherein the drive device is configured for: compensating an increase in the web tension caused by the orienting device as a consequence of magnetic induction; and/or reducing creasing of the carrier as a consequence of the web tension.

16. The transport device of claim 13, wherein the mutually phase-delayed alternating current is 3-phase alternating current.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Exemplary embodiments of the present invention are illustrated in the drawings and are explained in more detail below with further details and advantages being given.

[0027] FIG. 1 shows a schematic illustration of part of the transport device according to the present invention (in a lateral view);

[0028] FIG. 2 shows a schematic illustration of the transport device shown in FIG. 1, in a plan view from above;

[0029] FIG. 3 shows a schematic illustration of a magnetic roller as an alternating field generator; and

[0030] FIG. 4 shows a schematic illustration of a linear motor stator as an alternating field generator.

DETAILED DESCRIPTION OF THE INVENTION

[0031] FIG. 1 shows a lateral view of a schematic illustration of a transport device 1, in which a carrier 2 in the form of a foil that is used in the production of electrodes for lithium-ion batteries is moved in a direction of movement 3 relative to the floor B. The carrier 2 is provided with a coating that comprises graphite particles.

[0032] The graphite particles can be in the shape of flakes having a certain longitudinal extent. In this case, the particles are advantageously oriented so as to be perpendicular to the surface such that the ions flowing about the particles have to travel a shorter distance. In terms of the battery, this has substantial advantages, since the cell thus formed offers less resistance. There is thus less heat generation in general. Accordingly, the charging time can also be shortened by virtue of the shorter distances for the ions. Overall, the operation of such a cell is also substantially less hazardous as a result, since the reduced resistance, and thus the lower amount of heat when charging or discharging the cell, also reduces the risk of the cell overheating or even catching fire.

[0033] An orienting device 4 for orienting the particles is provided along a sub-section of the transport path. First, the coating is applied to the carrier 2 (not illustrated). The orienting device 4 generates a magnetic field which is variable in terms of time and/or location, the carrier 2, or the coating thereof, being exposed to the magnetic field. However, since the carrier 2 is composed of an electrically conductive material, this in the present case typically being a copper foil, inductive currents are created, which in turn generate a magnetic field which interacts with the magnetic field of the orienting device 4.

[0034] Since the carrier 2 here is transported in a roller-to-roller process, wherein at least one roller is configured as a driven roller, high tension as a result of this effect of force can also stress the carrier 2.

[0035] In order to be able to minimize or compensate this effect, respectively, an additional drive device 5 is provided, the latter here in the direction of movement 3 being disposed directly downstream of the orienting device 4.

[0036] FIG. 2 shows a plan view from above of the assembly from FIG. 1. As a result of magnetic induction, which emanates from the magnetic fields that are variable in terms of time or location and are generated by the orienting device, eddy currents 6 are generated in the carrier 2 (here a coated copper foil). The magnetic field resulting therefrom brakes the carrier 2, because the magnetic field interacts with the magnetic field of the orienting device 4. The braking force 7 is counter to the direction of movement 3.

[0037] In order for this effect to be equalized, an additional drive device 5 is provided, the latter in turn exerting a driving force 8 counter to the braking force 7. The drive device 5 is preferably configured for not contacting the carrier 2, thus for operating in a non-contacting manner, so as not to damage the coating of the carrier 2, or disturb the orientation of the particles contained in the latter, respectively.

[0038] It is illustrated in FIG. 3 how such a drive device 5 can be implemented. The drive device 5, or the alternating field generator, respectively, can be configured as a magnetic roller 13; i.e. the alternating field generator here is integrated in a cylindrical roller 11, permanent magnets 12 in a Halbach array being disposed along the circumference of the cylindrical roller 11. The arrows on the permanent magnets indicate the orientation of the respective magnetic field, or of the corresponding field lines, respectively. In order to provide a temporally changing magnetic field by way of which eddy currents can be generated inductively in the carrier 2, or which can exert a Lorentz force on the charges flowing in the carrier 2 as a consequence of the eddy currents, respectively, the roller 13 rotates at the rotating speed ω, here in the clockwise direction in FIG. 3.

[0039] In order to exert high accelerations on the carrier 2 during the linear movement of the latter, the stator 20 of a linear motor can also be used as the additional drive device 5. Grooves 22, which in each case accommodate the coils 23, 24, 25, are incorporated in the iron core 21. The coils 23, 24, 25 are passed through by a phase-delayed 3-phase alternating current. The arrangement with a linear motor typically requires a high power consumption and produces a lot of heat.

LIST OF REFERENCE SIGNS

[0040] 1 Transport device [0041] 2 Carrier [0042] 3 Direction of movement [0043] 4 Orienting device [0044] 5 Additional drive device [0045] 6 Eddy currents [0046] 7 Braking force [0047] 8 Additional driving force [0048] 11 Cylinder/roller [0049] 12 Permanent magnets [0050] 13 Magnetic roller [0051] 20 Stator of a linear motor [0052] 21 Iron core [0053] 22 Groove [0054] 23, 24, 25 Coils [0055] ω Rotating speed [0056] B Floor