Ultrasonic drying for battery electrode manufacturing

Abstract

A system for drying a battery electrode foil comprising a metal foil and a wet electrode coating layer is provided. The system comprises a battery electrode foil transport apparatus configured to transport the battery electrode foil along a transport direction; and at least one ultrasonic apparatus configured to be coupled to the battery electrode foil and configured to induce ultrasonic vibrations to the battery electrode foil transported by the battery electrode foil transport apparatus for drying the wet electrode coating layer by the ultrasonic vibrations.

Description

ULTRASONIC DRYING FOR BATTERY ELECTRODE MANUFACTURINGTECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to a system for drying a battery electrode foil comprising a metal foil and a wet electrode coating layer. Further embodiments relate to a method of drying a battery electrode foil comprising a metal foil and a wet electrode coating layer.BACKGROUND

[0002] The coating of electrodes for batteries requires vast amounts of energy. The drying of a wet electrode coating layer that is applied onto a battery electrode foil is particularly energy intensive and also requires a large footprint in a factory. The drying process is associated with a relatively low drying speed and thus a low coating speed. Typically, at least part of the moisture, be it water moisture or moisture of an organic solvent, in the wet electrode coating is being removed by employing thermal drying (heating). Even though this method is well-established, it is associated with high cost for energy and infrastructure.

[0003] Thus, improved drying systems and methods that reduce the cost and footprint of the battery electrode drying process may be desired.DISCLOSURE OF THE INVENTION

[0004] In the view of the foregoing, the present disclosure is directed to a system for drying a battery electrode foil comprising a metal foil and a wet electrode coating layer, and a method of drying a battery electrode foil comprising a metal foil and a wet electrode coating layer.

[0005] According to an aspect of the present disclosure, a system for drying a battery electrode foil is provided. The battery electrode foil comprises a metal foil and a wet electrode coating layer. The system comprises a battery electrode foil transport apparatus configured to transport the battery electrode foil along a transport direction; and at least oneultrasonic apparatus configured to be coupled to the battery electrode foil and configured to induce ultrasonic vibrations to the battery electrode foil transported by the battery electrode foil transport apparatus for drying the wet electrode coating layer by the ultrasonic vibrations.

[0006] According to another aspect of the present disclosure, a method of drying a battery electrode foil is provided. The battery electrode foil comprises a metal foil and a wet electrode coating layer. The method comprises transporting the battery electrode foil along an ultrasonic apparatus; and inducing ultrasonic vibrations to the battery electrode foil using the ultrasonic apparatus for drying the wet electrode coating layer by the ultrasonic vibrations.

[0007] According to some embodiments, the battery electrode foil comprises a metal foil. The metal foil may comprise aluminum and / or copper. Typically, the metal foil has a thickness of at least 2 pm, at least 5 pm or at least 10 pm. Typically, the metal foil has a thickness of at most 15 pm, at most 20 pm, at most 25 pm or at most 30 pm. In particular, the metal foil may have a thickness between 5 pm and 25 pm.

[0008] Typically, a wet slurry is prepared to provide the wet electrode coating layer. The wet slurry is coated onto the metal foil, in particular via a coating head. Typically, the wet slurry comprises battery active materials, polymer binders, and / or conductive additives. The wet slurry typically comprises a liquid, in particular water or an organic solvent, mixed with the battery active materials, polymer binders and / or conductive additives.

[0009] According to some embodiments, the wet electrode coating layer is coated on one side of the metal foil. In particular, the wet electrode coating layer may be coated on only one side of the metal foil, with the opposite side not being coated with the wet electrode coating layer. Typically, the wet electrode coating layer is coated on both sides of the metal foil. In particular, the metal foil comprises a first side and a second side, with the first side being opposite to the second side, and the wet electrode coating layer comprises a first wet electrode coating layer on the first side and a second wet electrode coating layer on the second side.

[0010] According to some embodiments, a dry electrode coating layer may have a thickness on one side of the metal foil of at least 30 gm, at least 40 gm, at least 50 gm or at least 60 gm. Typically, the dry electrode coating layer may have a thickness on one side of at most 70 gm, at most 80 gm, at most 100 gm or at most 150 gm. In particular, the dry electrode coating layer may have a thickness of 50 pm to 100 pm for an anode electrode or of 40 gm to 80 gm for a cathode electrode. Typically, the thickness of the dry electrode coating layer may be substantially equal for the first side and the second side.

[0011] Typically, the system for drying a battery electrode foil comprises a battery electrode foil transport apparatus. The battery electrode foil transport apparatus may be configured to transport the battery electrode foil along a transport direction. The transport direction is typically the direction in which the metal foil is moved to pass subsequent battery electrode manufacturing steps. In particular, the battery electrode foil transport apparatus may transport the metal foil from a coating section, in particular with the coating head, to a drying section along the transport direction. In typical embodiments, the transport direction is substantially parallel to a longitudinal axis of the metal foil. In other words, the metal foil substantially extends along the transport direction.

[0012] According to some embodiments, the battery electrode foil transport apparatus comprises at least one transport roll. In particular, the battery electrode foil transport apparatus comprises a plurality of transport rolls. Typically, the at least one transport roll is configured to rotate to move the battery electrode foil in the transport direction. In some embodiments, at least one of the transport rolls may change the orientation of the battery electrode foil. Exemplarily, the at least one transport roll may redirect the battery electrode foil. Typically, the at least one transport roll is in physical contact with the battery electrode foil, and particularly with the metal foil and / or wet electrode coating layer.

[0013] Typically, the system for drying a battery electrode foil comprises at least one ultrasonic apparatus. In particular, the system for drying a battery electrode foil comprises a plurality of ultrasonic apparatuses. The at least one ultrasonic apparatus is typically configured to be coupled to the battery electrode foil. In some embodiments, the at least one ultrasonic apparatus is coupled to the metal foil, in particular when only one side of the metal foil is coated. Coupling the ultrasonic apparatus to the metal foil advantageously provides aconsistent surface throughout the drying process, that is particularly independent of the degree of moisture in the wet electrode coating layer. In some embodiments, the at least one ultrasonic apparatus is coupled to the wet electrode coating layer. Coupling the ultrasonic apparatus to the wet electrode coating layer can advantageously provide a more efficient drying of the wet electrode coating layer.

[0014] In some embodiments, the system may be configured to modify a height position of the at least one ultrasonic apparatus. In particular, the height position may be defined as a relative value of a distance to the battery electrode foil. In some embodiments, the height position may be defined as an absolute value, exemplarily with respect to a factory floor or a fixed machine, such as the battery electrode foil transport apparatus. According to some embodiments, the height position influences a contact tightness of the at least one ultrasonic apparatus with respect to the battery electrode foil. The contact tightness may influence a drying performance and / or an integrity of the wet electrode coating layer. For an optimum drying performance, an optimized contact tightness is required. Typically, for a contact tightness too small, a reduced drying can be observed. For a contact tightness too large, mechanical damage to the wet electrode coating layer may be caused. The contact tightness may comprise a contact pressure, in particular a pressure the ultrasonic generator applies onto the sheet of material, or a stress present in the sheet of material due to an interaction with the ultrasonic generator. In some embodiments, the contact tightness may comprise a pressure exerted on the ultrasonic generator by the sheet of material.

[0015] The height position may be modified by an actuator. The actuator configured to modify a height position may be based on an electric signal or a pneumatic or a hydraulic signal. In particular, the actuator may comprise a hydraulic actuator, a pneumatic actuator or an electric motor. In some embodiments, the actuator may comprise a piezo stage. In some embodiments, the actuator may provide pre-defined height positions and may comprise a finite number of height positions. In some embodiments, the actuator may operate continuously.

[0016] In some embodiments, the ultrasonic drying apparatus, in particular the actuator and / or the ultrasonic apparatus, comprises a distance sensor, configured to determine a distance between the ultrasonic apparatus and the battery electrode foil. The actuator mayreceive a distance signal from the distance sensor and may control the distance between the ultrasonic apparatus and the battery electrode foil, in particular to maintain a desired distance received by the actuator. Exemplarily, a control loop may control settings of the actuator based on the distance signal and the desired distance.

[0017] In some embodiments, the ultrasonic apparatus is arranged on a top side of the battery electrode foil. The top side of the battery electrode foil may be the side facing away from the factory floor. In some embodiments, the ultrasonic apparatus is arranged on a bottom side of the battery electrode foil. The bottom side of the battery electrode foil may be the side facing the factory floor.

[0018] Typically, the at least one ultrasonic apparatus being configured to be coupled to the battery electrode foil comprises the ultrasonic apparatus being configured to be in physical contact with the battery electrode foil. In particular, the at least one ultrasonic apparatus may be arranged such that when the battery electrode foil transport apparatus transports a battery electrode foil along the transport direction, the at least one ultrasonic apparatus is coupled to, and in particular in contact with, the battery electrode foil. According to some embodiments, the at least one ultrasonic apparatus being configured to be coupled to the battery electrode foil may comprise the at least one ultrasonic apparatus being configured to modify the height position once a battery electrode foil is present to establish a coupling to the battery electrode foil.

[0019] According to some embodiments, the ultrasonic apparatus may comprise a piezoelectric transducer. In typical embodiments, the ultrasonic apparatus may comprise a plurality of piezoelectric transducers. In some embodiments, the ultrasonic generator may comprise a power supply, in particular configured to supply the ultrasonic apparatus with an alternating current (AC) voltage at a desired frequency. Typically, the ultrasonic apparatus comprises a resonance frequency. Typically, the ultrasonic apparatus is operated at or close to the resonance frequency. Typically, the ultrasonic apparatus is operated at a frequency of at least 20 kHz, at least 50 kHz or at least 80 kHz. Typically, the ultrasonic apparatus is operated at a frequency of at most 100 kHz, at most 150 kHz, at most 200 kHz, at most 250 kHz or at most 300 kHz. In particular, the ultrasonic generator is operated at a frequency between 50 kHz and 200 kHz, more in particular at a frequency of 110 kHz. In someembodiments, the frequency and / or amplitude of the ultrasonic vibrations generated by the ultrasonic apparatus may be fixed. Typically, the frequency and / or amplitude of the ultrasonic vibrations generated by the ultrasonic apparatus may be adjusted. The ultrasonic apparatus may be considered as an ultrasonic generator. In particular, the ultrasonic apparatus is typically in contact with the battery electrode foil and generates ultrasonic vibrations in the battery electrode foil. In particular, the ultrasonic apparatus induces vibrations in a contact surface of the battery electrode foil.

[0020] Typically, the ultrasonic apparatus comprises an oscillating element for creating the ultrasonic vibrations. The oscillating element may be part of a piezoelectric transducer. The oscillating element may be connected to a coupling portion. The coupling portion may be configured to be in direct physical contact with the battery electrode foil. In some embodiments, the coupling portion may be in indirect contact with the battery electrode foil, exemplarily an intermediate sheet may be arranged in between the coupling portion and the battery electrode foil. The oscillating element and the coupling portion may be integrated, and particularly be formed in one-piece.

[0021] According to some embodiments, at least one transport roll comprises an ultrasonic apparatus. In particular, the ultrasonic apparatus may cause a surface of the at least one transport roll to oscillate, in particular perpendicular to the transport direction. Typically, the surface of the at least one transport roll is a surface in contact with the battery electrode foil. Integrating the ultrasonic apparatus into the at least one transport roll may advantageously allow to reduce the complexity of the system for drying a battery electrode foil by reducing the number of devices involved. Integrating the ultrasonic apparatus into the at least one transport roll may advantageously reduce the number of surfaces in contact with the battery electrode foil, which can reduce the risk of unintentionally influencing the formation of the electrode coating layer. Integrating the ultrasonic apparatus into the at least one transport roll may advantageously reduce an exposure of the ultrasonic apparatus to mechanical influence and / or disturbances. In some embodiments, the system for drying a battery electrode foil may comprise an ultrasonic apparatus integrated in a transport roll and may additionally comprise an ultrasonic apparatus that is configured to directly contact the battery electrode foil. In other words, the system may comprise an ultrasonic apparatus integrated into a transport roll and a stand-alone ultrasonic apparatus.

[0022] According to some embodiments, the system comprises a plurality of ultrasonic apparatuses. Typically, the ultrasonic apparatuses are arranged in a predefined pattern. The pattern may comprise at least one line of ultrasonic apparatuses. The plurality of ultrasonic apparatuses may be arranged such that an operating area of each of the plurality of ultrasonic apparatuses overlaps with an operating area of another one of the plurality of ultrasonic apparatuses, in particular such that the battery electrode foil is being dried along the entire width of the battery electrode foil.

[0023] According to some embodiments, the pattern may comprise multiple lines of ultrasonic apparatuses with each line being parallel to each other and perpendicular to the transport direction. The pattern may comprise a staggered or matrix-like arrangement of the plurality of ultrasonic apparatuses. The pattern may follow a two-dimensional Bravais lattice pattern. In particular, the pattern may comprise an oblique, a rectangular, in particular a square, a centered rectangular, or a hexagonal lattice. In some embodiments, distances between neighboring ultrasonic apparatuses may vary, in particular throughout the width of the battery electrode foil. In particular, the density of ultrasonic apparatuses may be higher at a center of the battery electrode foil or at edges of the battery electrode foil.

[0024] According to some embodiments, the plurality of ultrasonic apparatuses comprises a first ultrasonic apparatus configured to be operated with at least one first operating setting, and a second ultrasonic apparatus configured to be operated with at least one second operating setting. The first operating setting may comprise a first operating frequency and / or a first amplitude of the ultrasonic vibrations. The second operating setting may comprise a second operating frequency and / or a second amplitude of the ultrasonic vibrations. In some embodiments, the first operating setting and / or the second operating setting may be adjusted. Typically, the first operating setting is different from the second operating setting. Exemplarily, the first operating frequency may be different from the second operating frequency. The system comprising ultrasonic apparatuses with different operating settings may advantageously allow to optimize the drying process at different stages of the drying process. Exemplarily, the first operating setting may provide a better drying performance at a first step of the drying process, exemplarily with a first degree of moisture in the wet electrode coating layer, than the second operating setting. At a later stage of the drying process, exemplarily with a second degree of moisture smaller than the first degree ofmoisture, the second operating setting may provide a better drying performance than the first operating setting.

[0025] According to some embodiments, in particular with ultrasonic apparatuses with fixed settings, the system comprising ultrasonic apparatuses with different operating settings may advantageously allow to dry a plurality of battery electrode foil configurations, exemplarily with respect to the thickness, composition or degree of moisture, with an acceptable performance.

[0026] According to some embodiments, the system for drying a battery electrode foil comprises an ultrasonic sensor. The ultrasonic sensor is typically configured to sense an amplitude and / or frequency of ultrasonic vibrations. In typical embodiments, the ultrasonic vibrations are emitted by at least one of the plurality of ultrasonic apparatuses, reflected by the battery electrode foil and sensed by the ultrasonic sensor. In some embodiments, the ultrasonic sensor may be integrated in the at least one ultrasonic apparatus, exemplarily as an ultrasonic transducer.

[0027] According to some embodiments, the at least one ultrasonic apparatus is configured to operate in a first frequency mode for drying the wet electrode coating layer and is configured to operate in a second frequency mode for sensing properties of the battery electrode foil. According to some embodiments, the sensed properties in the second frequency mode may be employed to modify operating settings in the first frequency mode. Typically, the sensed properties may comprise a liquid content of the wet electrode coating layer, a degree of moisture of the wet electrode coating layer, a density of the wet electrode coating layer, a density and / or a presence of defects in the wet electrode coating layer and / or a density and / or a presence of cracks in the wet electrode coating layer. In other words, the ultrasonic sensor may be employed to control a quality of the wet electrode coating layer. Typically, the first frequency mode comprises frequencies lower than the frequencies of the second frequency mode. In some embodiments, the frequencies of the second frequency mode are lower than the frequencies of the first frequency mode.

[0028] Typically, the second frequency mode comprises frequencies of at least 50 kHz, at least 100 kHz or at least 200 kHz. The second frequency mode may comprise frequencies of at most 500 kHz, at most 1 MHz, at most 2.5 MHz, at most 10 MHz or at most 25 MHz. Inparticular, the second frequency mode may comprise frequencies of the ultrasonic vibrations between 100 kHz and 10 MHz and preferably between 200 kHz and 2.5 MHz.

[0029] Typically, the first frequency mode for drying the wet electrode coating layer may comprise frequencies of at least 20 kHz, at least 50 kHz or at least 80 kHz. Typically, the ultrasonic apparatus is operated at a frequency of at most 100 kHz, at most 150 kHz, at most 200 kHz, at most 250 kHz or at most 300 kHz. In particular, the ultrasonic generator is operated at a frequency between 50 kHz and 200 kHz, more in particular at a frequency of 110 kHz.

[0030] According to some embodiments, the at least one ultrasonic apparatus is configured to operate in a third frequency mode. In some embodiments, the third frequency mode may comprise frequencies between the frequencies of the first frequency mode and the frequencies of the second frequency mode. In some embodiments, the third frequency mode comprises frequencies smaller than the frequencies of the first frequency mode and the frequencies of the second frequency mode. Typically, the third frequency mode may comprise frequencies of at least 5 kHz, at least 10 kHz, or at least 20 kHz and / or of at most 30 kHz, at most 40 kHz or at most 50 kHz. Typically, the ultrasonic apparatus may employ the third frequency mode to improve a mixing behavior of the wet electrode coating layer. In particular, a separation of the wet electrode coating layer, in particular during the drying process, may be avoided.

[0031] According to some embodiments, the ultrasonic sensor may comprise a measurement ultrasonic generator, configured to generate ultrasonic vibrations to be induced to the battery electrode foil and to be measured by the ultrasonic sensor. In particular, the measurement ultrasonic generator is distinct from the ultrasonic apparatus. Employing a separate measurement ultrasonic generator may advantageously allow to sense properties of the battery electrode foil, and particularly of the wet electrode coating layer, at the same time while drying the wet electrode coating layer.

[0032] According to some embodiments, the system for drying a battery electrode foil comprises a control apparatus. Typically, the control apparatus is connected and / or in communication with the at least one ultrasonic apparatus to control operating settings of the at least one ultrasonic apparatus. In particular, the control apparatus may provide a frequencyand / or an amplitude of the ultrasonic vibrations to be emitted to the at least one ultrasonic apparatus. In some embodiments, the control apparatus may control the height position of the at least one ultrasonic apparatus.

[0033] According to some embodiments, the control apparatus may be connected to and or in communication with the ultrasonic sensor. In particular, the control apparatus may receive properties of the battery electrode foil, and particularly of the wet electrode coating layer. The control apparatus may modify the operating settings of the at least one ultrasonic apparatus in view of the properties received. In particular, the control apparatus may employ a control loop to modify the operating settings when a property of the battery electrode foil changes.

[0034] According to some embodiments, the control apparatus may receive information from a distributed control system (DCS), in particular on the composition of the battery electrode foil or a geometrical distribution of the wet electrode coating layer on the metal foil. In some embodiments, the control apparatus may receive information from a battery electrode foil transport apparatus controller, in particular via the DCS. The information from the battery electrode foil transport apparatus controller may comprise a transport speed of the battery electrode foil.

[0035] According to some embodiments, the system for drying a battery electrode foil comprises at least one quality control sensor. Typically, the at least one quality sensor may sense a quality of the battery electrode foil, in particular of the wet electrode coating layer. Typically, the quality sensed may comprise a liquid content of the wet electrode coating layer, a degree of moisture of the wet electrode coating layer, a density of the wet electrode coating layer, the density and / or the presence of defects in the wet electrode coating layer and / or the density and / or the presence of cracks in the wet electrode coating layer. In some embodiments, the quality may comprise a distribution of the wet electrode coating layer on the metal foil and / or a, particularly chemical, homogeneity of the wet electrode coating layer. The at least one quality control sensor may comprise an infrared sensor, a nucleonic sensor, a microwave sensor, a camera sensor and / or a temperature sensor. In some embodiments, the at least one quality control sensor may comprise a spectrometer. In some embodiments,the at least one quality sensor may comprise an analysis module configured to analyze data obtained from a physical sensor and configured to provide a quality indicator.

[0036] Typically, the control apparatus controls at least one ultrasonic apparatus based on at least one parameter provided by the at least one quality control sensor. In particular, the control apparatus may modify an amplitude and / or a frequency of the ultrasonic vibrations emitted by the at least one ultrasonic apparatus. In some embodiments, the control apparatus may modify a height of the at least one ultrasonic apparatus. According to some embodiments, the at least one quality sensor may comprise an interface configured to establish a connection with the DCS.

[0037] According to some embodiments, the system for drying a battery electrode foil may comprise a heating chamber. Typically, the heating chamber is configured to convectively dry the wet electrode coating layer. In particular, the heating chamber comprises at least one heating element configured to heat the battery electrode foil, particularly the wet electrode coating layer. Typically, the heating chamber may be configured to heat the battery electrode foil above at least a boiling point of the liquid, in particular of water or the organic solvent. In some embodiments, the heating chamber may be configured to heat the battery electrode foil, in particular the wet electrode coating layer, to at least 60°C, at least 70°C, at least 80°C, at least 90°C, at least 100°C, at least 120°C, at least 140°C or at least 160°C. Preferably, the heating chamber may be configured to heat the battery electrode foil to at least 80°C.

[0038] According to some embodiments, the heating chamber may comprise a plurality of heating sub chambers. In particular, the heating chamber may comprise 2, 3, 4, 5, 8, 10 or more heating sub chambers. Typically, at least a first heating sub chamber and a second heating sub chamber may heat the battery electrode foil to a different temperature. Having a plurality of sub chambers may advantageously allow to heat the battery electrode foil along temperature profiles, particularly to avoid excess thermal stress. Typically, the heating chamber comprises a heating controller, in particular to control the temperature of the heating chamber.

[0039] According to some embodiments, the system for drying a battery electrode foil, in particular the heating chamber, may comprise at least one air nozzle to remove evaporated liquid, in particular water vapor or organic solvent vapor, from a vicinity of the batteryelectrode foil. Typically, the air nozzle is configured to induce an air stream along the battery electrode foil. In some embodiments, the air stream is introduced by positive or negative pressure with respect to the air pressure within the system for drying a battery electrode foil, and particularly within the heating chamber.

[0040] According to some embodiments, the at least one ultrasonic apparatus is arranged upstream, in a transport direction of the battery electrode foil, of the heating chamber. In particular, the at least one ultrasonic apparatus may be arranged prior to any heating stage. Typically, the at least one ultrasonic apparatus may be arranged at a position of the system for drying a battery electrode foil, where the degree of moisture exceeds 75%, exceeds 85%, exceeds 90%, exceeds 95%, or exceeds 99% of the initial degree of moisture of the wet coating layer. The initial degree of moisture may be the degree of moisture immediately after coating of the wet coating layer on the metal foil. Typically, the at least one ultrasonic apparatus may be arranged between a coating head and the heating stage, in particular the heating chamber.

[0041] According to some embodiments, at least one ultrasonic apparatus is arranged within the heating chamber. In particular, the ultrasonic vibrations are induced to a section of the battery electrode foil while the section of the battery electrode foil is heated by the heating chamber. The control apparatus may be in communication with the heating controller, particularly to control the at least one ultrasonic apparatus based on the temperature of the heating chamber. Arranging the ultrasonic apparatus within the heating chamber may advantageously allow to retrofit existing heating chambers with an additional drying system. Advantageous effects of ultrasonic drying and convective drying may be combined.

[0042] According to some embodiments, the at least one ultrasonic apparatus is arranged downstream, in a transport direction of the battery electrode foil, of the heating chamber. In other words, the battery electrode foil passes the heating chamber prior to passing the at least one ultrasonic apparatus. Typically, the at least one ultrasonic apparatus may be arranged at a position of the system for drying a battery electrode foil, where the degree of moisture is below 25%, below 15%, below 10%, below 5%, or below 1% of the initial degree of moisture of the wet coating layer.

[0043] According to some embodiments, a first ultrasonic apparatus may be arranged upstream of the heating chamber and a second ultrasonic apparatus may be arranged downstream of the heating chamber or within the heating chamber. In some embodiments, the first ultrasonic apparatus may be arranged in the heating chamber and the second ultrasonic apparatus may be arranged downstream of the heating chamber. In particular, the first ultrasonic apparatus may operate at a first operating setting different from a second operating setting of the second ultrasonic apparatus. According to some embodiments, the first ultrasonic apparatus may be arranged upstream of the heating chamber, the second ultrasonic apparatus may be arranged within the heating chamber and a third ultrasonic apparatus may be arranged downstream of the heating chamber. The operating settings of the first ultrasonic apparatus may be different from the operating settings of the second ultrasonic apparatus and of the third ultrasonic apparatus. The operating settings of the second ultrasonic apparatus may be different from the operating settings of the third ultrasonic apparatus.

[0044] According to some embodiments, the at least one ultrasonic apparatus may be arranged in a vacuum chamber. In particular, the vacuum chamber may have a pressure of at most 0.7 bar, at most 0.5 bar, at most 0.3 bar, at most 0.2 bar, at most 0.1 bar, at most 50 mbar or at most 20 mbar. The vacuum chamber may be part of the heating chamber. In other words, the heating chamber and the vacuum chamber may be integrated. Typically, the system for drying a battery electrode foil may comprise a vacuum pump, in particular for evacuating the vacuum chamber. Arranging the at least one ultrasonic apparatus in a vacuum chamber may advantageously improve the drying performance.

[0045] According to some embodiments, a method of drying a battery electrode foil comprises transporting the battery electrode foil along an ultrasonic apparatus and inducing ultrasonic vibrations to the battery electrode foil using the ultrasonic apparatus for drying the wet electrode coating layer by the ultrasonic vibrations. Typically, the method comprises sensing quality parameters of the wet battery electrode foil and adjusting operating parameters of the ultrasonic apparatus based on the sensed quality parameters of the battery electrode foil. In some embodiments, the quality parameters are sensed upstream of the ultrasonic apparatus. In some embodiments, the quality parameters are sensed downstreamof the ultrasonic apparatus. Typically, the method may be executed by a system according to embodiments described herein.

[0046] Embodiments of the present disclosure provide an improved drying of battery electrode foils. The drying performance is improved by inducing ultrasonic vibrations to the battery electrode foil. The present disclosure allows for an improved drying of battery electrode foils with a reduced energy consumption and a reduced footprint. Investment costs for drying systems for battery electrode foils may be reduced.BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings relate to embodiments of the disclosure and are described in the following:FIG la schematically illustrates a system for drying a battery electrode foil according to embodiments described herein;FIG lb schematically illustrates a system for drying a battery electrode foil according to embodiments described herein;FIG 1c schematically illustrates a system for drying a battery electrode foil according to embodiments described herein;FIG 2a schematically illustrates a system for drying a battery electrode foil according to embodiments described herein;FIG 2b schematically illustrates a system for drying a battery electrode foil according to Fig. 2a from a different perspective;FIG 2c schematically illustrates a system for drying a battery electrode foil according to Fig. 2a from a different perspective;FIG 3 schematically illustrates a system for drying a battery electrode foil according to embodiments described herein;FIG 4 schematically illustrates a system for drying a battery electrode foil according to embodiments described herein;FIG 5a schematically illustrates a system for drying a battery electrode foil according to embodiments described herein;FIG 5b schematically illustrates a system for drying a battery electrode foil according to embodiments described herein;FIG 5c schematically illustrates a system for drying a battery electrode foil according to embodiments described herein;FIG 6 schematically illustrates a system for drying a battery electrode foil according to embodiments described herein;FIG 7 schematically illustrates a method for drying a battery electrode foil according to embodiments described herein.DETAILED DESCRIPTION OF EMBODIMENTS

[0048] Reference will now be made in detail to the various embodiments of the disclosure, one or more examples of which are illustrated in the figures. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation of the disclosure and is not meant as a limitation of the disclosure. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield a further embodiment. It is intended that the description includes such modifications and variations. In the figures, elements may be depicted with exaggerated dimensions to improve the comprehensibility of the detailed description of embodiments. Further, some elements may be depicted with enlarged dimensions while other elements in the same figure are depicted, relatively, with reduced dimensions.

[0049] Fig la schematically illustrates a system 100 for drying a battery electrode foil 10. The battery electrode foil 10 comprises a metal foil 11 and a wet electrode coating layer 12. In Fig. la, the metal foil 11 is coated on one side with the wet electrode coating layer 12. However, in embodiments not shown in the figures, the metal foil 11 may be coated with a wet electrode coating layer 12 on both sides of the metal foil 11. The metal foil 11 is coated via a coating head 25. The coating head 25 deposits the wet electrode coating layer 12 on the metal foil 11.

[0050] The system 100 comprises a battery foil transport apparatus. The battery foil transport apparatus comprises a plurality of transport rolls. In Fig. la, two transport rolls 20a, 20b are shown. The plurality of transport rolls 20a, 20b mechanically support the battery electrode foil 10 and transport the battery electrode foil 10 along the transport direction T. The system 100 comprises an ultrasonic apparatus 30. The ultrasonic apparatus 30 is coupled to the battery electrode foil 10, in particular to the metal foil 11.

[0051] In Fig. lb, the ultrasonic apparatus 30 is coupled to the wet electrode coating layer 12 of the battery electrode foil 10. In embodiments not shown in the figures, the system 100 may comprise an ultrasonic apparatus coupled to the metal foil 11, as shown in Fig. la, and an ultrasonic apparatus coupled to the wet electrode coating layer 12, as shown in Fig. lb.

[0052] In Fig. 1c, the ultrasonic apparatus 30 is arranged within a transport roll 20b of the battery electrode foil transport apparatus. In particular, the ultrasonic apparatus induces ultrasonic vibrations to the battery electrode foil 10 via a contact surface of the transport roll 20b. In Fig. 1c, the transport roll 20b is in contact with the metal foil 11 of the battery electrode foil 10. In embodiments not shown in the figures, the transport roll 20b may be in contact with the wet electrode coating layer 12.

[0053] In Fig. 2a, the system 100 comprises a plurality of ultrasonic apparatuses 30a, 30b, 30c. The plurality of ultrasonic apparatuses 30a, 30b, 30c are arranged along the transport direction T. In Fig. 2a, the plurality of ultrasonic apparatuses 30a, 30b, 30c are arranged to contact the metal foil 11. In embodiments not explicitly shown in the figures some or all of the plurality of ultrasonic apparatuses may be arranged to contact the wet electrode coating layer 12.

[0054] In Fig. 2b and Fig. 2c, the plurality of ultrasonic apparatuses, as exemplarily shown by a longitudinal section in Fig. 2a, is shown as a schematic top or bottom view. The plurality of ultrasonic apparatuses 30a-30r is arranged in a pattern. In the patterns shown Fig. 2b and Fig. 2c, the pattern comprises three columns extending transversal to the transport direction T and six lines along the transport direction T. However, the exemplary pattern shown in Fig. 2b and Fig. 2c may be replicated for a larger number of ultrasonic apparatuses.

[0055] In Fig. 2b the plurality of ultrasonic apparatuses 30a-30r is arranged in a tetragonal pattern. In Fig. 2c, the plurality of ultrasonic apparatuses 30a-30r is arranged in a staggered pattern. The pattern of Fig. 2c may also be described as a rhombohedral pattern.

[0056] In Fig. 3, the system 100 comprises a quality control sensor 50 and a control apparatus 40. The quality control sensor 50 may comprise an emitting unit and a sensing unit. The emitting unit and the sensing unit may be arranged on opposite sides of the battery electrode foil 10. Typically, the quality control sensor 50 provides a quality parameter to thecontrol apparatus 40. The control apparatus 40 interprets the quality parameter and controls the ultrasonic apparatus 30 based on the quality parameter. In Fig. 3, the quality control sensor 50 is arranged downstream of the ultrasonic apparatus 30. In other words, a section of the battery electrode foil 10 passes the ultrasonic apparatus 30 prior to the quality control sensor 50 when moving in the transport direction T.

[0057] In Fig. 4, the system comprises an ultrasonic sensor 31. The ultrasonic sensor 31 is typically arranged in the vicinity of the ultrasonic apparatus 30. The ultrasonic sensor 31 is configured to sense ultrasonic vibrations reflected from the battery electrode foil 10.

[0058] In Fig. 5a, the system 100 comprises a heating chamber 60. The heating chamber 60 comprises a plurality of sub chambers 61, 62, 63. The battery electrode foil 10 is transported through the heating chamber 60 by the battery electrode foil transport apparatus comprising a plurality of transport rolls 20a-20h. The ultrasonic apparatus 30 is arranged upstream of, in other words prior to, the heating chamber 60 in the transport direction T. In particular, the ultrasonic apparatus 30 is arranged between the coating head 25 and the heating chamber 60.

[0059] In Fig. 5b, the ultrasonic apparatus 30 is arranged within the heating chamber 60. In particular, the ultrasonic apparatus is arranged within an intermediate sub chamber 61.

[0060] In Fig. 5c, the ultrasonic apparatus 30 is arranged downstream of, in other words subsequent to, the heating chamber 60. In other words, the battery electrode foil 10 passed through the heating chamber 60 prior to passing the ultrasonic apparatus 30 in the transport direction T. The heating chamber 60 is arranged between the coating head 25 and the ultrasonic apparatus 30.

[0061] In embodiments not shown in the figures, the positions as shown in Fig. 5a, 5b and 5c may be combined. In other words, a plurality of ultrasonic apparatuses 30 may comprise at least one first ultrasonic apparatus arranged upstream of the heating chamber 60, at least one ultrasonic apparatus 30 within the heating chamber 60 and at least one ultrasonic apparatus 30 downstream of the heating chamber 60. In some embodiments, only two of the positions may be used, exemplary at least one ultrasonic apparatus is arranged before the heating chamber and at least one ultrasonic apparatus is arranged after the heating chamber.

[0062] In Fig. 6, the system 100 comprises a vacuum chamber 70. The ultrasonic apparatus 30 is arranged in the vacuum chamber 70. The battery electrode foil 10 passes through the vacuum chamber 70 and passes along the ultrasonic apparatus 30 in the vacuum chamber 70. In some embodiments that are not explicitly shown in the figures, the heating chamber 60 and the vacuum chamber 70 may be integrated. In other words, the heating chamber 60 may be evacuated or the vacuum chamber 70 may comprise a heating element.

[0063] Fig. 7 shows a method 700 of drying a battery electrode foil. The method comprises transporting 710 the battery electrode foil along an ultrasonic apparatus; and inducing 720 ultrasonic vibrations to the battery electrode foil using the ultrasonic apparatus for drying the wet electrode coating layer by the ultrasonic vibrations.

Claims

CLAIMS1. A system (100) for drying a battery electrode foil (10) comprising a metal foil (11) and a wet electrode coating layer (12), the system (100) comprising: a battery electrode foil transport apparatus (20a-20h) configured to transport the battery electrode foil (10) along a transport direction (T); and at least one ultrasonic apparatus (30) configured to be coupled to the battery electrode foil (10) and configured to induce ultrasonic vibrations to the battery electrode foil (10) transported by the battery electrode foil transport apparatus (20a-20h) for drying the wet electrode coating layer (12) by the ultrasonic vibrations.

2. The system (100) of claim 1, wherein the at least one ultrasonic apparatus (30) is configured to be coupled to the metal foil (11) of the battery electrode foil (10).

3. The system (100) of claim 1, wherein the at least one ultrasonic apparatus (30) is configured to be coupled to the wet electrode coating layer (12) of the battery electrode foil (10).

4. The system (100) of any of the preceding claims, wherein the battery electrode foil transport apparatus (20a-20h) comprises at least one transport roll (20b); and the at least one transport roll (20b) comprises an ultrasonic apparatus (30).

5. The system (100) of any of the preceding claims, wherein the system (100) comprises a plurality of ultrasonic apparatuses (30a-30r) arranged in a predefined pattern.

6. The system (100) of any of the preceding claims, wherein the at least one ultrasonic apparatus (30) comprises a first ultrasonic apparatus configured to be operated with at least one first operating setting, and a second ultrasonic apparatus configured to be operated with at least one second operating setting different from the at least one first operating setting.

7. The system (100) of any of the preceding claims, wherein the system (100) comprises an ultrasonic sensor (31); and the at least one ultrasonic apparatus (30) is configured to operate in a first frequency mode for drying the wet electrode coating layer (12) and is configured to operate in a second frequency mode for sensing, with the ultrasonic sensor (31), properties of the battery electrode foil (10); wherein the first frequency mode comprises a different frequency than the second frequency mode.

8. The system (100) of any of the preceding claims, wherein the system (100) further comprises a control apparatus (40) and at least one quality control sensor (50); and the control apparatus (40) controls at least one ultrasonic apparatus (30) based on at least one parameter provided by the at least one quality control sensor (50).

9. The system (100) of claim 8, wherein controlling the at least one ultrasonic apparatus (30) comprises adjusting a frequency and / or an amplitude of the ultrasonic vibrations emitted by the at least one ultrasonic apparatus (30).

10. The system (100) of any of the preceding claims, further comprising a heating chamber (60) configured to convectively dry the wet electrode coating layer (12).

11. The system (100) of claim 10, wherein at least one ultrasonic apparatus (30) is arranged upstream, in a transport direction (T) of the battery electrode foil (10), of the heating chamber (60).

12. The system (100) of any of claims 10 to 11, wherein at least one ultrasonic apparatus (30) is arranged within the heating chamber (60).

13. The system (100) of any of the preceding claims, wherein the system (100) comprises a vacuum chamber (70); andat least one ultrasonic apparatus (30) is arranged within the vacuum chamber (70).

14. A method (700) of drying a battery electrode foil (10) comprising a metal foil (11) and a wet electrode coating layer (12), the method (700) comprising: transporting (710) the battery electrode foil (10) along an ultrasonic apparatus (30); and inducing (720) ultrasonic vibrations to the battery electrode foil (10) using the ultrasonic apparatus (30) for drying the wet electrode coating layer (12) by the ultrasonic vibrations.

15. The method (700) of claim 14, further comprising: sensing quality parameters of the battery electrode foil (10); adjusting operating parameters of the ultrasonic apparatus (30) based on the sensed quality parameters of the battery electrode foil (10).

Images