Steam drying for battery electrode manufacturing

Abstract

A multi-stage system (100) for drying a battery electrode foil (10) comprising a metal foil (11) and a wet electrode coating layer (12) is provided. The system (100) comprises a battery electrode foil transport apparatus (20a, 20b) configured to transport the battery electrode foil (10) on a transport path along a transport direction (T); an electrode coating layer drying system (15) configured for receiving the battery electrode foil (10) and for drying the battery electrode foil (10) by applying heat to the wet electrode coating layer (12); and at least one steambox (30) configured to preheat the wet electrode coating layer (12) and being arranged upstream of the battery electrode drying system (15) in the transport direction (T).

Description

STEAM 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 drying 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 to 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 multi-stage 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 on a transport path along a transportdirection; an electrode coating layer drying system configured for receiving the battery electrode foil and for drying the battery electrode foil by applying heat to the wet electrode coating layer; and at least one steambox configured to preheat the wet electrode coating layer and being arranged upstream of the battery electrode drying system in the transport direction.

[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 a steambox configured to preheat the wet electrode coating layer; and subsequently transporting the battery electrode foil through an electrode coating layer drying system configured for receiving the battery electrode foil and for drying the battery electrode foil by applying heat to the wet electrode coating layer.

[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, particularly N-Methyl-2-pyrrolidone (NMP), 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] According to some embodiments, the battery electrode foil transport apparatus comprises a transport apparatus controller. The transport apparatus controller is typically configured to control a transport velocity of the battery electrode foil transport apparatus. In particular, the transport apparatus controller may control a rotation speed of the at least one transport roll.

[0014] Typically, the multi-stage system for drying the battery electrode foil comprises at least two drying stages. Exemplarily, the multi-stage system may be a two-stage system or may comprise 3, 4, 5, 6, 10 or more drying stages. In some embodiments, at least two drying stages of the multi-stage system employ a different drying technology. In other words, a first drying stage dries the wet electrode coating layer by a first process and the second drying stage dries the wet electrode coating layer by a second process different from the first process. Typically, the battery electrode foil transport apparatus is configured to transport the battery electrode foil through the multi-stage system. Particularly, the battery electrode foil transport apparatus transports the battery electrode foil through the multi-stage system. Typically, the battery electrode foil passes the at least two drying stages subsequently.

[0015] Typically, the multi-stage system comprises an electrode coating layer drying system configured for receiving the battery electrode foil and for drying the battery electrode foil. The multi-stage drying system typically is configured to dry the battery electrode foil by applying heat to the wet electrode coating layer. Typically, the electrode coating layer drying system may comprise at least one of a convective air furnace, a cylinder dryer system or an inductive heating system. In some embodiments, the electrode coating layer system may comprise a combination of different drying technologies, particularly integrated or arranged subsequently. Exemplarily, the electrode coating layer system may comprise a combination of a convective air furnace and a cylinder dryer system. Typically, to heat the cylinder dryer system, steam, and exemplarily overheated steam, is provided to an interior of the cylinder dryer system heating a surface in contact with the electrode coating layer. In some embodiments, the electrode coating layer drying system may comprise an ultrasonic drying system.

[0016] Typically, the multi-stage system comprises at least one steambox configured to preheat the wet electrode coating layer. The at least one steambox is arranged upstream of the battery electrode drying system in the transport direction. In particular, the battery electrode foil transport apparatus typically transports the battery electrode foil along the at least one steambox prior to transporting the battery electrode foil to the electrode coating layer drying system. In other words, in normal operation, each section of the battery electrode foil with the wet electrode coating layer passes the at least one steambox prior to being dried by the electrode coating layer drying system.

[0017] The at least one steambox is typically configured to preheat the wet electrode coating layer. In particular, the at least one steambox is configured to increase the temperature of the wet electrode coating layer by at least 10 K, at least 20 K, at least 40 K, or at least 60 K. In some embodiments, the at least one steambox is configured to increase the temperature of the wet electrode coating layer to at least 40 °C, 50 °C, 80 °C, or 100 °C. In some embodiments, the wet electrode coating layer is preheated by the at least one steambox starting from a substantially ambient temperature, exemplarily starting from a temperature of 20 °C or 25 °C. Preheating the wet electrode coating layer using the at least one steambox prior to the electrode coating layer drying system may advantageously reduce a heating and drying time, reduce damages in the electrode coating layer, exemplarily reduce cracks, reduce an overall footprint of a battery electrode drying system and / or reduce costs.

[0018] In some embodiments, the at least one steambox comprises a plurality of steamboxes. Typically, at least one second steambox of the plurality of steamboxes is arranged downstream in the transport direction of at least part of the electrode coating layer drying system. In some embodiments, the electrode coating layer drying system may comprise a plurality of chambers or sections, particularly with a first section of the plurality of sections having a different temperature than a second section of the plurality of sections. Typically, the at least one second steambox may be arranged between the first section and the second section. The at least one second steam box may be configured to heat the wet electrode coating layer from the temperature in the first section to the temperature in the second section.

[0019] In some embodiments, the at least one steambox comprises a steambox hood. The steambox hood typically comprises a plurality of openings. Particularly, at least some of the plurality of openings face the transport path and typically the wet electrode coating layer of the battery electrode foil transported along the transport path. The at least one steambox is typically configured to provide superheated steam to the wet electrode coating layer. In some embodiments, superheated steam comprises superheated steam of a solvent employed for coating the wet electrode coating layer. Particularly, the term steam is to be understood as generally relating to vapours of solvents, and more particularly of battery electrode coating solvents. Exemplarily, the solvent may be water or N-Methyl-2-pyrrolidone (NMP). Thesuperheated steam may be water vapour steam, NMP vapour steam or vapour of another solvent.

[0020] In some embodiments, the superheated steam may be produced, and particularly heated, in the at least one steambox. In some embodiments, the superheated steam may be provided to the steambox from an external entity, exemplarily from a steam supply system of an industrial plant. In some embodiments, the superheated steam may be provided to the steambox and may further be heated by the steambox. Particularly, the at least one steambox may be configured to control a temperature of the superheated steam. In some embodiments, the exhaust steam may be employed to heat at least one cylinder of a cylinder drying system. Typically, superheated steam comprises steam at a temperature higher than the vaporization point of the solvent.

[0021] In some embodiments, the at least one steambox is configured to provide the superheated steam at a first area covered by the steambox hood. Typically, the steambox is configured to provide the superheated steam at the first area with a positive pressure, in other words with a pressure exceeding the pressure outside the steambox hood. The superheated steam typically interacts with the battery electrode foil at the first area, and particularly with the wet electrode coating layer. Particularly, the superheated steam heats, and more particularly preheats, the battery electrode foil at the first area. The steambox hood and the battery electrode foil typically form an interaction volume. Within the interaction volume, the superheated steam can interact with the battery electrode foil. Particularly, the interaction volume comprises the first area and the second area. Typically, a length of the interaction volume in the transport direction exceeds a height of the interaction volume, i.e. a distance between the steambox and the battery electrode foil. Particularly, the length of the interaction volume in the transport direction exceeds a height of the interaction volume by a factor of at least 2, at least 3 or at least 5.

[0022] In some embodiments, the at least one steambox is configured to remove exhaust steam subsequent to a contact of the superheated steam with the wet electrode coating layer. The exhaust steam is typically cooler than the superheated steam prior to the contact with the wet electrode coating layer. Typically, the exhaust steam is removed at a second area covered by the steambox hood. The second area is typically different from the first area. Inother words, the superheated steam is typically provided to the wet electrode coating layer via a different pathway than it is removed from the wet electrode coating layer. Typically, the steambox is configured to remove the exhaust steam at the second area with a negative pressure, in other words with a pressure below the pressure outside the steambox hood. In some embodiments, the at least one steambox comprises at least one fan for providing the positive pressure at the first area and / or for providing the negative pressure at the second area. In some embodiments, the exhaust steam may be reused in a different part of a battery electrode production process, which may advantageously be associated with a reduced amount of energy required for the battery electrode production process.

[0023] In some embodiments, the first area and the second area are substantially in the same foil-facing plane of the steambox hood. In some embodiments, the foil-facing plane may be curved, particularly following a curved transport path. Typically, the foil-facing plane and the transport path and / or the battery electrode foil are substantially parallel. Typically, the first area and the second area are arranged adjacent to each other. In particular, a boundary of the first area may be a boundary of the second area. Exemplarily, an edge of a wall of the steambox may separate the first area from the second area. In some embodiments, the first area and the second area may be arranged in a substantially nested arrangement.

[0024] In some embodiments, the steambox, and particularly the steambox hood, is arranged on one side of the battery electrode foil. Particularly, the steambox, and particularly the steambox hood, is arranged on the wet electrode coating layer side of the battery electrode foil. The superheated steam is typically provided from the same side of the battery electrode foil from which the exhaust steam is removed.

[0025] In some embodiments, particularly for a battery electrode foil comprising two wet electrode coating layers, at least one steambox is arranged on each side of the transport path, or, in other words, on each side of the battery electrode foil. Having at least one steambox arranged on each side of the battery electrode foil may advantageously allow to preheat both wet electrode layers.

[0026] In some embodiments, the battery electrode foil transport apparatus comprises at least one transport roll. Typically, at least one steambox is arranged adjacent to one of the atleast one transport roll of the battery electrode foil transport apparatus. Particularly, the at least steambox is arranged adjacent to a transport roll configured to change the orientation of the battery electrode foil. In some embodiments, the at least one steambox, and particularly a transport path facing contour of the steambox hood substantially follows a shape of the transport roll.

[0027] Typically, the at least one steambox is arranged adjacent to the transport path. Typically, the transport path defines the position of the battery electrode foil when the battery electrode foil is being transported through the multi-stage system. Particularly when the system is in operation, the at least one steambox is arranged adjacent to the battery electrode foil and, more particularly, to the wet electrode coating layer. The at least one steambox being arranged adjacent to the transport path may particularly comprise the steambox being arranged at a distance of at most 20 mm, at most 50 mm or at most 100 mm from the transport path. The distance of the steambox and the transport path may comprise a distance perpendicularly to the transport path and particularly to the battery electrode foil. The distance between the steambox and the transport path, and particularly between the steambox and the wet electrode coating layer, may be defined as a distance of the first and / or second area of the steambox to the transport path or to the wet electrode coating layer.

[0028] According to some embodiments, the at least one steambox may be operated along at least one operating setting. The at least one operating setting may comprise a temperature setting, which may particularly comprise a temperature set-point for the temperature of the superheated steam, a pressure setting, which may particularly comprise a pressure set-point for the pressure of the superheated steam, or a flow or stream setting, which may particularly comprise a set-point for the volume flow or stream of the superheated steam.

[0029] According to some embodiments, at least one steambox comprises a plurality of operating zones. Particularly, in a first operating zone, the at least one steambox is configured to be operated with at least one first operating setting and in a second operating zone, the at least one steambox is configured to be operated with at least one second operating setting. Typically, the at least one second operating setting is different from the at least one first operating setting. In some embodiments the plurality of operating zones maybe arranged along the transport direction or may be arranged perpendicular to the transport direction.

[0030] Typically, the at least one first operating setting and the at least one second operating setting may differ with respect to a temperature of the superheated steam, a pressure of the superheated steam and / or a rate of flow of the superheated steam. Typically, the at least one first operating setting and the at least one second operating setting may be adjustable. In particular, the steambox may comprise a plurality of actuators to adjust the at least one first operating setting and the at least one second operating setting. The at least one first operating setting and the at least one second operating setting may be adjusted based upon a control signal received from a controller, a control apparatus, or from a distributed control system (DCS). In some embodiments, the at least one first operating setting and the at least one second operating setting may be adjusted based upon a signal of at least one quality control sensor.

[0031] In some embodiments, the multi-stage system comprises a control apparatus. The control apparatus is configured to control the at least one steambox and / or the battery electrode foil transport apparatus. The control apparatus may comprise an interface to communicate with a distributed control system (DCS). Particularly, the control apparatus may receive a level of preheating required from the DCS. Exemplarily, the control apparatus may receive a desired temperature of the wet electrode layer coating to be reached by the at least one steambox. Typically, the multi-stage system comprises at least one quality control sensor. The at least one quality control sensor may be configured to determine a quality parameter of the battery electrode foil, and particularly of the wet electrode coating layer.

[0032] Typically, the at least one quality sensor may sense a quality parameter of the battery electrode foil, in particular of the wet electrode coating layer. Typically, the quality parameter 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 parameter 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. In someembodiments, the quality parameter may comprise a temperature 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.

[0033] In some embodiments, at least one quality control sensor may be arranged downstream of at least one steambox, particularly to obtain a quality indicator or parameter of a preheated battery electrode foil. In some embodiments, the at least one quality control sensor may be arranged upstream of at least one steambox, particularly to obtain a quality indicator or parameter of a battery electrode foil to be preheated by the steambox. The at least one steambox may, at least in part, be controlled based upon the parameter obtained by the at least one quality sensor. Typically, the control apparatus receives the parameter provided by the at least one quality control sensor and controls the at least one steambox and / or the battery electrode foil transport apparatus based upon the parameter received. In particular, the control apparatus may employ a control loop, and exemplarily a closed-loop control loop, to modify the operating settings when a property of the battery electrode foil changes. Typically, the control apparatus comprises a closed-loop controller.

[0034] 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 steambox and / or of the battery electrode foil transport apparatus in view of the properties received. Exemplarily, the control apparatus may modify a transport velocity of the battery electrode foil transport apparatus. In some embodiments, controlling the at least one steambox comprises adjusting at least one of a pressure of superheated steam in the at least one steambox, a temperature of superheated steam in the at least one steambox or a rate of flow of superheated steam in the at least one steambox.

[0035] In some embodiments, the quality control sensor is configured to determine a quantitative indication of a structural integrity of the battery electrode foil. Particularly, the quality control sensor is configured to quantitively determine the presence, density and / or severity of cracks in the electrode coating layer.

[0036] In some embodiments, the quality control sensor is configured to determine a quantitative indication of a moisture content of the wet electrode coating layer. In particular, the quality control sensor may determine an average moisture content or a moisture distribution in the wet electrode coating layer. The control apparatus may particularly control the at least one steambox to operate the first operating zone differently from the second operating zone based upon a spatial distribution of a quality parameter, exemplarily of the moisture content, of the battery electrode foil.

[0037] In some embodiments, the quality control sensor is configured to determine a quantitative indication of a temperature of the battery electrode foil. Particularly, the quality control apparatus may comprise a thermometer or a thermal camera to determine the temperature or a temperature distribution of the battery electrode foil.

[0038] According to some embodiments, a method of drying a battery electrode foil comprises transporting the battery electrode foil along a steambox configured to preheat the wet electrode coating layer. Typically, the method comprises subsequently transporting the battery electrode foil through an electrode coating layer drying system configured for receiving the battery electrode foil and for drying the battery electrode foil by applying heat to the wet electrode coating layer. In some embodiments, the quality parameters are sensed upstream of the steambox. In some embodiments, the quality parameters are sensed downstream of the steambox. Typically, the method comprises adjusting operating parameters of the steambox based on the sensed quality parameters of the battery electrode foil. Typically, the method may be executed by a system according to embodiments described herein.

[0039] Embodiments of the present disclosure provide an improved drying of battery electrode foils. The drying performance is improved by preheating the battery electrode foil with the wet electrode coating layer. Preheating the battery electrode foil using at least one steambox reduces a footprint required in an industrial plant for drying the battery electrode foil. The present disclosure allows for an improved drying of battery electrode foils with a reduced energy consumption. Employing superheated steam advantageously exploits the superior heat transfer properties of superheated steam in comparison to air. Further, superheated steam exhibits no resistance to diffusion of evaporated moisture in its ownvapour, which may lead to higher drying rates. The multi-stage system may be implemented based upon already existing drying systems by appropriately adding at least one steambox according to the present disclosure. Investment costs for drying systems for battery electrode foils may be reduced.BRIEF DESCRIPTION OF THE DRAWINGS

[0040] 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 2 schematically illustrates a steambox according to embodiments described herein;FIG 3 schematically illustrates a system for drying a battery electrode foil according to embodiments described herein;FIG 4 schematically illustrates a method for drying a battery electrode foil according to embodiments described herein.DETAILED DESCRIPTION OF EMBODIMENTS

[0041] 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.

[0042] 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.

[0043] 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 a steambox 30 and an electrode coating layer drying system 15. The electrode coating layer drying system 15 is configured to dry the battery electrode foil 10 by applying heat to the battery electrode foil 10, the metal foil 11 and / or the wet electrode coating layer 12. The steambox 30 is arranged upstream of the electrode coating layer drying system 15 in the transport direction T. In other words, a segment of the battery electrode foil 10 being transported through the system 100 in the transport direction T passes along the steambox 30 prior to passing the electrode coating layer drying system 15. The steambox 30 is arranged adjacent to the battery electrode foil 10, and particularly to the wet electrode coating layer 12. The steambox 30 is arranged on the wet electrode coating layer 12 facing side of the battery electrode foil 10.

[0044] In Fig lb, the steambox 30 is arranged adjacent to a transport roll 20a. The transport roll 20a is configured to change a direction of the battery electrode foil 10. The steambox 30 is arranged substantially tangential to the curvature of the battery electrode foil 10. In Fig.1c, the system 100 of Fig. lb further comprises a second steambox 30b. The electrode coating layer drying system 15 comprises two sections 15a, 15b. The second steambox 30b is arranged downstream of the first section 15a of the electrode coating layer drying system 15 in the transport direction T. The second steambox 30b is arranged upstream of the second section 15b of the electrode coating layer drying system 15. In embodiments not shown in the figures, the second steambox may be arranged downstream of the overall electrode coating layer drying system 15.

[0045] In Fig 2, an exemplary steambox 30 is shown in a sectional view. The steambox 30 has a substantially trapezoidal cross-section and typically has substantially the shape of a truncated pyramid or a prism. The steambox 30 comprises a steambox hood 31. Typically, the steambox hood 31 comprises a substantially open surface. The open surface comprises openings through which superheated steam may exit or enter the steambox 30. Typically, the open surface faces the battery electrode foil. Typically, a distance of the steambox 30 to the battery electrode foil is smaller than a length of the steambox 30 along the transport direction T. The steambox hood 31 substantially defines an exterior shape of the steambox 30. The steambox hood 31 confines superheated steam within the steambox 30. Within the steambox 30, steam is guided towards the battery electrode foil via a central region of the steambox 30 and is removed from the battery electrode foil via peripheral regions of the steambox 30. The steambox 30 comprises an actuator 35, and particularly a plurality of actuators 35, to control properties of the steam. Exemplarily, the actuator 35 may control a volume flow, a pressure or a temperature of the steam through the steambox 30. Steam provided and controlled by the actuator is distributed on the wet electrode coating layer with a diffuser assembly 36. The diffuser assembly 36 comprises a plurality of openings through which the steam can reach a first area 33 covered by the steambox hood 31. In the first area 33, the superheated steam is provided to the wet electrode coating layer and can preheat the wet electrode coating layer. The steambox hood 31 further comprises a plurality of openings 32 through which exhaust steam can be removed from the wet electrode coating layer. The plurality of openings 32 are arranged in a second area 34 of the surface of the steambox 30 facing the battery electrode foil. The second area 34 is arranged adjacent to the first area 33. Particularly, in the sectional view of Fig 2, the first area 33 is nested inside the second area 34.

[0046] 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. In embodiments, not shown in the figures, the emitting unit and the sensing unit are arranged on the same side of the battery electrode foil 10. Typically, the quality control sensor 50 provides a quality parameter to the control apparatus 40. The control apparatus 40 interprets the quality parameter and controls the steambox 30 and / or the battery foil transport apparatus, and particularly the transport roll 20a, based on the qualityparameter. In Fig 3, the quality control sensor 50 is arranged downstream of the steambox 30. In other words, a section of the battery electrode foil 10 passes the steambox 30 prior to the quality control sensor 50 when moving in the transport direction T.

[0047] Fig 4 shows a method 400 of drying a battery electrode foil comprising a metal foil and a wet electrode coating layer. The method 400 comprises transporting 410 the battery electrode foil along a steambox configured to preheat the wet electrode coating layer. The method 400 further comprises subsequently transporting 420 the battery electrode foil through an electrode coating layer drying system configured for receiving the battery electrode foil and for drying the battery electrode foil by applying heat to the wet electrode coating layer.

Claims

CLAIMS1. A multi-stage 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, 20b) configured to transport the battery electrode foil (10) on a transport path along a transport direction (T);an electrode coating layer drying system (15) configured for receiving the battery electrode foil (10) and for drying the battery electrode foil (10) by applying heat to the wet electrode coating layer (12); andat least one steambox (30) configured to preheat the wet electrode coating layer (12) and being arranged upstream of the electrode coating layer drying system (15) in the transport direction (T).

2. The system (100) of claim 1,wherein the at least one steambox (30) comprises a steambox hood (31) with a plurality of openings (32); andwherein the at least one steambox (30) is configured to provide superheated steam to the wet electrode coating layer (12) at a first area (33) covered by the steambox hood (31) and to remove exhaust steam subsequent to a contact of the superheated steam with the wet electrode coating layer (12) at a second area (34) covered by the steambox hood (31) different from the first area.

3. The system (100) of claim 2, wherein the first area (33) and the second area (34) are arranged adjacent to each other.

4. The system (100) of any of the preceding claims, whereinthe battery electrode foil transport apparatus (20a, 20b) comprises at least one transport roll (20a); andat least one steambox (30) is arranged adjacent to one of the at least one transport roll (20a).

5. The system (100) of any of claims 3 - 4, wherein at least one steambox (30) is arranged adjacent to the transport path.

6. The system (100) of claim 5, wherein at least one steam box (30) is arranged at a distance of at most 100 mm perpendicular to the transport path.

7. The system (100) of any of the preceding claims, wherein at least one steambox (30) comprises a plurality of operating zones; andwherein in a first operating zone, the at least one steambox (30) is configured to be operated with at least one first operating setting, and in a second operating zone, the at least one steambox (30) is configured to be operated with at least one second operating setting different from the at least one first operating setting.

8. The system (100) of any of the preceding claims, whereinthe system (100) further comprises a control apparatus (40) and at least one quality control sensor (50) configured to determine a quality parameter of the battery electrode foil; andthe control apparatus (40) controls at least one steambox (30) and / or the battery electrode foil transport apparatus (20a, 20b) based on at least one parameter provided by the at least one quality control sensor (50).

9. The system (100) of claim 8, wherein the control apparatus (40) comprises a closed-loop controller.

10. The system (100) of any of claims 8 -9, wherein controlling the at least one steambox (30) comprises adjusting at least one of a pressure of steam, a temperature of steam, or a rate of flow of steam in the at least one steambox (30).

11. The system (100) of any of claims 8 - 10, wherein the quality control sensor (50) is configured to determine a quantitative indication of a structural integrity of the battery electrode foil (10).

12. The system (100) of any of claims 8 - 11, wherein the quality control sensor (50) is configured to determine a quantitative indication of a moisture content of the wet electrode coating layer (12).

13. The system (100) of any of any of claims 8 - 12, wherein the quality control sensor (50) is configured to determine a temperature of the wet electrode coating layer (12).

14. The system (100) of any of the preceding claims, wherein the electrode coating layer drying system (15, 15a, 15b) comprises a convective air furnace.

15. The system (100) of any of the preceding claims, wherein the electrode coating layer drying system (15, 15a, 15b) comprises a cylinder dryer system.

16. The system (100) of any of the preceding claims, wherein the electrode coating layer drying system (15, 15a, 15b) comprises an inductive heating system.

17. The system (100) of any of the preceding claims, whereinthe system (100) comprises a plurality of steamboxes (30, 30b); andat least one steambox (30a) is arranged downstream in the transport direction (T) of at least part of the electrode coating layer drying system (15a).

18. A method (400) of drying a battery electrode foil (10) comprising a metal foil (11) and a wet electrode coating layer (12), the method (700) comprising:transporting (410) the battery electrode foil (10) along a steambox (30) configured to preheat the wet electrode coating layer (12); andsubsequently transporting (420) the battery electrode foil (10) through an electrode coating layer drying system (15) configured for receiving the battery electrode foil (10) and for drying the battery electrode foil (10) by applying heat to the wet electrode coating layer (12).

19. The method (700) of claim 18, further comprising:sensing quality parameters of the battery electrode foil (10);adjusting operating parameters of the steambox (30) based on the sensed quality parameters of the battery electrode foil (10).

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