Calender for producing an electrode film from a powdered electrode precursor material, corresponding method and corresponding electrode film

Description

[0001] The invention is based on a calender for producing an electrode film from a powdered electrode precursor material, having at least a first and a second squeezing roller rotating counter to the first, between which a roller gap is formed, wherein the calender is designed to subject the powdered electrode precursor material to shear forces as it is passed through the roller gap and in the process to form an electrode film.

[0002] Electrodes can be used in electrical energy storage cells, which are widely used to power electronic, electromechanical, electrochemical, and other useful devices. Such cells include batteries such as primary chemical cells and secondary (rechargeable) cells, fuel cells, and various types of capacitors, including ultracapacitors. Electrodes can also be used in water treatment systems. Electromobility, in particular, is gaining unmistakable growth. The energy source in electric vehicles, the battery, accounts for a large portion of the costs. This is directly related to its production. Therefore, efficient and cost-effective production is required, with a simultaneous increase in energy density. The calendering process within the process chain for manufacturing battery cells, such as lithium-ion battery cells, is crucial to this.

[0003] Electrodes are key components for the storage potential of an energy storage device. The electrochemical capabilities of electrodes, e.g., the capacity and efficiency of battery electrodes, are determined by various factors. These include the distribution of the active material, the binder, and additives; the physical properties of the materials contained therein, such as the particle size and surface area of ​​the active material; the surface properties of the active materials; and the physical properties of the electrode film, such as density, porosity, cohesion, and adhesion to a conductive element. Dry processing systems and processes traditionally use a high-shear and / or high-pressure processing step to disrupt and mix the electrode film materials. Such systems and processes can contribute to structural advantages over wet-formed electrode films.However, high processing pressures and large system dimensions (and thus the large space requirements) required for the production of dry, self-supporting electrode films and dry electrodes leave room for improvement.

[0004] From the publication US 2020 / 0 227 722 A1, a multi-roll calender for producing a dry electrode for an energy storage device is known. The system comprises a first feed system for dry electrode material, a plurality of calender rolls arranged one behind the other, and a control system. The calender rolls are arranged such that they each form a gap between them. A first roll gap is provided to receive the dry electrode material from the first feed system for dry electrode material and to form a dry electrode film from the dry electrode material.

[0005] The multi-roll calender known from the prior art has the disadvantage that the calender rolls can deflect laterally due to the forces acting in the roll gaps, resulting in inaccuracies in the thickness of the electrode film being produced and causing vibrations in the system. This problem becomes more pronounced the larger the roll widths and the smaller the roll diameters are chosen. However, in light of the increasing demand for lithium-ion battery cells, it is necessary to use rolls with larger widths and, in some cases, smaller diameters to increase plant productivity and improve electrode quality. Therefore, there is a need for solutions that prevent the aforementioned problems.

[0006] The object of the present invention is therefore to improve a calender such that it enables greater process stability and is designed to produce a more uniform electrode film. The calender according to the invention thus enables a simplified and more cost-effective process for producing electrodes.

[0007] The object is achieved by a device, a method or an electrode film having the respective features of the independent claims.

[0008] Accordingly, it is provided that at least one of the first or second squeeze rollers has at least one pretensioning device for pretensioning the squeeze roller against a non-axial, in particular radial and / or tangential, force vector acting on the respective squeeze roller, generated in the roller gap by the compression process, by means of which the pretensioning direction and / or the magnitude of the pretensioning force can be adjusted.

[0009] The calender according to the invention has, among other things, the advantage that an electrode web formed by the calender does not have to be self-supporting, since it can be positioned on and supported by a calender roll during at least some, if not all, process steps. For example, the electrode web can be supported by at least one calender roll during all process steps within a multi-roll calendering system, including the lamination step when the electrode web is laminated to a metal foil to form an electrode.

[0010] An energy storage device produced using the calender according to the invention can have any suitable configuration, e.g., planar, spiral-wound, button-shaped, toothed, or pouch-shaped. The energy storage device can be a component of a system, e.g., a power generation system, an uninterruptible power supply (UPS) system, a photovoltaic power generation system, or an energy recovery system for use in, e.g., industrial machinery and / or transportation. The energy storage device can be used to power various electronic devices and / or motor vehicles, including hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and / or electric vehicles (EVs).

[0011] It can be provided that both squeeze rollers are each mounted in a machine frame via their front-end roll necks, wherein the pretensioning device is assigned to at least one bearing of the first or the second squeeze roller, wherein the roll neck can be deflected radially in any direction and to an adjustable extent relative to the at least one bearing by means of the pretensioning device. The squeeze rollers can each have a central calendering section which has a larger diameter than the roll necks. The roll gap can be formed between the calendering sections so that the roll gap length can correspond to the length of the calendering sections. It can be provided that the powdered electrode precursor material is conveyed evenly over the roll gap length into the roll gap so that an electrode film with the most homogeneous thickness distribution possible is produced.

[0012] In particular, it can be provided that the pretensioning device has a double eccentric, wherein the double eccentric has an inner eccentric bushing and an outer eccentric bushing, which can be rotated independently of one another. The inner eccentric bushing can be received at least partially in the outer eccentric bushing. An outer surface of the inner eccentric bushing can lie opposite an inner surface of the outer eccentric bushing. Play can be provided between the inner and outer eccentric bushings. The inner eccentric bushing can protrude partially from the outer eccentric bushing. The outer eccentric bushing can have a section extending away from the inner eccentric bushing. The inner eccentric bushing can have an outer diameter which is smaller than the inner diameter of the outer eccentric bushing. The inner eccentric bushing can further have an inner bore for receiving a roll neck.The inner bores of the inner and outer eccentric bushings can be arranged eccentrically with respect to their respective outer diameters. The eccentricities of the inner bushing and the outer eccentric bushing can be coordinated such that, in an initial position, a roll neck received in the inner eccentric bushing is received or positioned centrally in the double eccentric. The calender can have a device for axially rotating the inner eccentric bushing. The calender can further have a device for axially rotating the outer eccentric bushing. This allows the inner and outer eccentric bushings to be rotated independently of one another. It can be provided that the magnitude of the deflection can be adjusted by rotating the inner and outer eccentric bushings relative to one another.Furthermore, it can be provided that the direction of the deflection can be adjusted by rotating both eccentric bushings relative to the bearing journal. The double eccentric, in conjunction with the associated roller bearing, can cause the roller to bend. The roller bearing can be arranged on the roller further toward the center of the roller, axially spaced from the double eccentric.

[0013] It is conceivable that the first or second squeezing roller is rotatably mounted in the inner eccentric bushing. The respective roller journal can extend at least partially into the pretensioning device or the inner eccentric bushing.

[0014] Furthermore, it can be provided that the outer eccentric bushing is rotatably mounted relative to a bore arranged in the machine frame, in which the preloading device is accommodated. The bore can be made directly in the machine frame. Alternatively, the bore can be a cylinder liner inserted into the machine frame. A first radial bearing can be formed or arranged between the bore and the outer eccentric bushing.

[0015] Furthermore, the inner eccentric bushing can be rotatably mounted relative to the outer eccentric bushing. A second radial bearing can be formed or arranged between the outer eccentric bushing and the inner eccentric bushing.

[0016] Furthermore, a third radial bearing can be formed or arranged between the inner eccentric bushing and the roll neck. The first and / or second and / or third radial bearings can be designed as cylindrical roller bearings or needle bearings.

[0017] To generate sufficient pressing force in the roll gap and to provide a counterbearing for generating the preload force, a first backup roll can be arranged adjacent to the first squeeze roll and a second backup roll adjacent to the second squeeze roll, each of which rotates in the opposite direction. In particular, it can be provided that the backup rolls have a larger diameter than the first and second squeeze rolls. For example, the rolls can have a diameter of approximately 150-250 mm, preferably 200 mm, and the backup rolls can have a diameter of 600-800 mm, preferably 700 mm. It can be provided that, in an initial position of the double eccentric, the axes of the squeeze rolls and the backup rolls are aligned in one plane with one another.

[0018] It can be provided that the first squeeze roller and the first backup roller roll on one another and a roller gap is formed between the second squeeze roller and the second backup roller for guiding the electrode film through, wherein the second squeeze roller is designed to guide the electrode film around the top or bottom of the second squeeze roller. Direct contact can be provided between the first backup roller and the first squeeze roller so that the first squeeze roller can be supported on the first backup roller. The provided roller gap can space the second squeeze roller and the second backup roller from one another. However, the second squeeze roller can be supported indirectly on the second backup roller via the electrode film guided through the roller gap.

[0019] Above the roller gap between the first and second squeeze rollers, a device for continuously conveying powdered electrode precursor material into the roller gap can be arranged. The device can have a hopper that holds the powdered electrode precursor material and can extend across the entire width of the roller gap. The hopper can have a conveying gap on its underside for selectively conveying the powder into the roller gap.

[0020] It can be provided that at least one of the first or second squeeze rollers has a pretensioning device on its opposite roll necks. However, it can also be provided that both the first and second squeeze rollers have a pretensioning device on their opposite roll necks. This allows both squeeze rollers to be pretensioned independently of one another or against one another.

[0021] The invention further relates to a method for producing an electrode film having a homogeneous thickness from a powdered electrode precursor material, comprising the steps: Conveying powdered electrode precursor material into a nip formed by two nip rolls; passing the powdered electrode precursor material through the nip, wherein the powdered electrode precursor material is subjected to shear forces as it passes through the nip, so that an electrode film is formed; applying a bias voltage to at least one of the two nip rolls in order to counteract a force vector resulting from the passing of the powdered electrode precursor material through the nip onto the respective nip roll.

[0022] It can be provided that the application of a preload comprises the radial deflection of at least one roll neck of the respective squeezing roll.

[0023] Furthermore, it can be provided that the radial deflection of the at least one roll neck comprises the relative and / or uniform rotation of a double eccentric provided on the roll neck. The relative and / or uniform rotation can, in particular, affect an inner and an outer eccentric bushing of the double eccentric.

[0024] It can be provided that the radial deflection comprises the deflection of two opposing roll necks of at least one of the squeezing rolls, with both roll necks being deflected radially in the same direction. The same direction can mean, for example, that both roll necks are deflected downward or, in a plan view of the roll axis, horizontally toward one side of the roll axis.

[0025] Furthermore, it can be provided that the radial deflection comprises the deflection of two opposing roll necks of both of the squeezing rolls, wherein the opposing roll necks are each deflected in the same direction and the roll necks of the first and second squeezing rolls are deflected in the same or diametrically opposite directions. For example, adjacent roll necks can both be deflected downward or upward, toward or away from each other.

[0026] The method may further comprise supporting the two nip rollers on the sides of the nip rollers facing away from the nip by means of a linear force acting radially on the nip rollers. The linear force can, for example, be transmitted via support rollers arranged adjacent to the two nip rollers.

[0027] The invention further relates to an electrode film which has a homogeneous thickness such that the thickness variation of the electrode film across its width is not more than 10 µm, obtainable by passing a powdered electrode precursor material through a roller gap formed between a first and a second squeeze roller and in the course of this subjecting the powdered electrode precursor material to shear forces so that an electrode film is formed, thereby applying a bias to at least one of the squeeze rollers in order to counteract a force vector resulting from the passing of the powdered electrode precursor material through the roller gap onto the respective squeeze roller.

[0028] The electrode film may be one or more of an anode film, a cathode film, a separator film, a current collector film, an interlayer film, an adhesive film, a primer film, or a laminate of several of the foregoing films.

[0029] Further details of the invention are explained with reference to the following figures. Fig. 1 is a schematic view of a double eccentric for radially deflecting a bearing journal; Fig. 2 is a schematic view of a possible deflection of a roll caused by radial deflection of the roll journals; Fig. 3 is a side view of the installation situation of two calenders according to the invention arranged end-to-end; Fig. 4 is a perspective view of a roll alignment with no or prevented deflection; Fig. 5A is an illustration of the interaction of the double eccentric with a resulting horizontally inward deflection of the calender rolls in the roll gap; Fig. 5B is an illustration of the interaction of the double eccentric with a resulting horizontally outward deflection of the calender rolls in the roll gap; Fig. 5C is an illustration of the interaction of the double eccentric with a resulting counter-vertical deflection of the calender rolls in the roll gap;5D: Illustration of the interaction of the double eccentric with a resulting counter-shaped vertical deflection of the calender rolls in the roll gap; Fig. 6A: A perspective view of the calender rolls in conjunction with adjacent support rolls; Fig. 6B: A perspective view of the calender rolls in conjunction with adjacent support rolls and powdered electrode precursor material conveyed into the roll gap or an electrode film formed behind the roll gap; Fig. 7A: A perspective view of the calender rolls in conjunction with adjacent support rolls, wherein both calender rolls exhibit an evasive bending due to the compaction process, whereby the electrode film has an inhomogeneous thickness distribution; Fig.Fig. 7B is a perspective view of the calender rolls in conjunction with adjacent support rolls, wherein one of the calender rolls exhibits deflection induced by the compacting process, as a result of which the electrode film has an inhomogeneous thickness distribution; Fig. 8A is a perspective view of the calender rolls in conjunction with adjacent support rolls, wherein the electrode film has a homogeneous thickness distribution due to correct calender roll alignment; Fig. 8B is a perspective view of the calender rolls in conjunction with adjacent support rolls, wherein the electrode film has a homogeneous thickness distribution due to correct calender roll alignment, wherein the electrode film is guided around one of the support rolls; Fig. 9A is an exemplary side view of the process of electrode film production in the calender according to the invention; Fig.Fig. 9B is an exemplary plan view of the electrode film production process in the calender according to the invention; Fig. 10 is a perspective view of a roll neck mounted in a pretensioning device according to the invention.

[0030] FIG. 1 shows an exemplary double eccentric 99, which serves to deflect a roll neck 205 at any angle orthogonal to the center axis of the respective squeezing roll 201, 202 and within an adjustable magnitude. The double eccentric 99 has an outer eccentric bushing 101, the inner bore of which is eccentric with respect to the outer diameter. The double eccentric 99 further has an inner eccentric bushing 102, the inner bore of which, in an initial position, is concentric with the outer diameter of the outer eccentric bushing. The double eccentric 99 is configured such that it exerts a deflection on the squeezing roll 201, 202 via deflection of the roll neck 205 having the pretensioning device 100, so that a deflection of the squeezing roll can be counteracted by a force vector F generated in the roll gap by the electrode powder.The inner and outer eccentric bushings 102, 103 are rotatable relative to each other or in the same direction, so that the eccentricity of the inner bore of the inner eccentric bushing is adjustable, with the direction and degree of deflection being variable. Each of the eccentric bushings 102, 103 has a thick section and a thin section opposite the thick section. In the initial position described above, the thick section of the outer eccentric bushing 101 and the thin section of the inner eccentric bushing 102 are approximated, and the thin section of the outer eccentric bushing 101 and the thick section of the inner eccentric bushing 102 are approximated. By rotating both eccentric bushings 101, 102 relative to each other by 180°, the greatest possible off-center deflection can be achieved.

[0031] FIG. 2 illustrates the possible deflection of a squeezing roller 201, each having a pretensioning device 100 on each of its two opposite roll necks 205, which can be achieved by rotating the eccentric bushings 101, 102 relative to their starting position. This includes the representation of the rotation of the eccentric bushings 101, 102, which leads to a deflection of the roll necks 205 vertically downwards, the rotation of the eccentric bushings 101, 102, which leads to a deflection of the roll necks 205 horizontally to the left, the rotation of the eccentric bushings 101, 102, which leads to a deflection of the roll necks 205 vertically upwards, and the rotation of the eccentric bushings 101, 102, which leads to a deflection of the roll necks 205 horizontally to the right. The corresponding direction of rotation of the inner eccentric bushing and the outer eccentric bushing is shown.For example, to deflect the roll neck 205 vertically upward, the outer eccentric bushing 101, together with the inner eccentric bushing 102, is first rotated approximately 120° counterclockwise, as shown, and the inner eccentric bushing 102 is then rotated approximately 90° clockwise relative to the outer eccentric bushing 101. The other deflection positions are set accordingly, as indicated by the arrow directions shown.

[0032] Fig. 3 shows a side view of a calender 10, which shows the arrangement of the rolls 201, 202 in relation to the support rolls 301, 302 in the integrated rolling system according to one embodiment. The calender 10 is used to produce a separator film 303 coated on both sides with electrode films 613. The arrangement 2 has two calender assemblies positioned end-on, which have opposing main conveying directions Y1, Y2. The calender assemblies each have six rolls 301, 201, 202, 302, 401, wherein the input-side end roll 301 is designed as a support roll 301 rolling directly on the first nip roll 201, and the output-side end rolls form a common end roll gap 13.A separator film 303 is fed vertically from above to the end roll gap 13, which is coated on both sides by means of the electrode films 613 produced in the two calender arrangements, so that the coated separator film 303 leaves the end roll gap 13 vertically downwards and can then be cut to length and / or rolled up or further processed.

[0033] FIG. 4 shows the alignment of the nip rollers 201, 202 without deflection, so that one or more pretensioning devices 100 provided on the nip rollers 201, 202 are in their initial position. This alignment includes a nip roller 201 positioned adjacent to and parallel to a second nip roller 202.

[0034] FIG. 5A-5D show the interaction of the inner and outer eccentric bushings 102, 202 on the squeeze rollers 201, 202 in aligning the deflection of the squeeze rollers against a force vector F acting in the roller gap 210. FIG. 5A shows a squeezing roller 201 in alignment with a second squeezing roller 202, wherein the eccentric bushings 102, 102 of the first squeezing roller 201 are aligned such that they generate a deflection of the roller journals 205 horizontally to the left and thus a roller deflection horizontally to the right, and the eccentric bushings 102, 102 of the second squeezing roller 202 are aligned such that they generate a deflection of the roller journals 205 horizontally to the right and thus a roller deflection horizontally to the left. FIG. 5B shows a squeezing roller 201 in alignment with a second squeezing roller 202, wherein the eccentric bushings 102, 102 of the first squeezing roller 201 are aligned such that they generate a deflection of the roller journals 205 horizontally to the right and thus a roller deflection horizontally to the left, and the eccentric bushings 102, 102 of the second squeezing roller 202 are aligned such that they generate a deflection of the roller journals 205 horizontally to the left and thus a roller deflection horizontally to the right. FIG. 5C shows a squeezing roller 201 in alignment with a second squeezing roller 202, wherein the eccentric bushings 102, 102 of the first squeezing roller 201 are aligned such that they generate a deflection of the roller journals 205 vertically upwards and thus a roller deflection vertically downwards, and the eccentric bushings 102, 102 of the second squeezing roller 202 are aligned such that they generate a deflection of the roller journals 205 vertically downwards and thus a roller deflection vertically upwards. FIG. 5D shows a squeezing roller 201 in alignment with a second squeezing roller 202, wherein the eccentric bushings 102, 102 of the first squeezing roller 201 are aligned such that they generate a deflection of the roller journals 205 vertically downwards and thus a roller deflection vertically upwards, and the eccentric bushings 102, 102 of the second squeezing roller 202 are aligned such that they generate a deflection of the roller journals 205 vertically upwards and thus a roller deflection vertically downwards.

[0035] The FIG. 6A-6B show the alignment of the nip rolls 201, 202 with the backup rolls 301, 302 and the use of the rolls to produce an electrode film 613. This includes an arrangement of adjacent rolls, including, from left to right, a first backup roll 301, a first nip roll 201, a second nip roll 202, and a second backup roll 302, all aligned with each other. The powdered electrode precursor material 905 is fed from above into a nip 210 between the two nip rolls 201, 202 and formed therein into an electrode film 613, which exits the nip 210 at the underside of the nip rolls 201, 202.

[0036] The FIG. 7A-7B show the inadmissible thickness tolerance resulting from the deflection of the squeezing rollers 201, 202 when they are not pre-tensioned by the pre-tensioning device 100 according to the invention. Due to the pressing forces in the squeezing rollers 201, 202 resulting from the conveying of the electrode powder 905 through the squeezing roller gap 210, the squeezing rollers 201, 202 experience an upward deflection or yield to the pressing forces. This leads to the production of an electrode film 613 with an inadmissible thickness tolerance, whereby the thickness of the film can increase particularly towards the center. As shown in FIG. 7B As shown, the deflection behavior of the squeezing rollers 201, 202 can also be asymmetrical, so that only one of the squeezing rollers 201, 202, or both of them, is deflected to varying degrees. In the example shown, only the second squeezing roller 202 deflects upward, while the first squeezing roller 201 does not experience any deflection. This is because there is higher friction between the first squeezing roller 201 and the first support roller 301 due to the direct contact, while the friction between the second squeezing roller 202 and the electrode film 613 is lower.

[0037] The FIG. 8A-8B show an electrode film 613 with a uniform layer thickness, produced by correctly aligned nip rolls 201, 202 according to one embodiment. Correctly adjusted pretensioning devices 100 ensure that the two nip rolls 201, 202 are correctly aligned so that there is no net deflection, or the process and pretensioning forces present in the nip balance each other out, resulting in the production of a film 613 with a homogeneous thickness distribution. Fig. 8B illustrates the further transport of the electrode film 613, which is guided meandering around the rollers in a main conveying direction.

[0038] During operation, the squeeze rollers 201, 202 are deflected to adjust the film 613 that forms when the dry powder mixture 905 is passed through the roller nip 210. In some embodiments, the deflection of the roll necks 205 is about 5 µm, about 10 µm, about 15 µm, about 20 µm, about 25 µm, about 30 µm, about 35 µm, about 40 µm, about 45 µm, about 50 µm, about 55 µm, about 60 µm, about 65 µm, about 70 µm, about 75 µm, about 80 µm, about 85 µm, about 90 µm, about 95 µm or about 100 µm, in each case based on a roll with a diameter of about 200 mm. Alternatively, the amount of deflection can be expressed as a ratio selected based on the overall dimension of the pressure roll. In one embodiment, the deflection ratio is about 2.5 x 10 -5 to about 0.0005, about 5 x 10 -5 to about 0.0005, or about 7.5 x 10 -5 to about 0.0005, based on the amount of deflection of the roll divided by the roll diameter.Although the above values ​​are based on a squeezing roller with a diameter of 200 mm, the diameter of the roller is not so limited.

[0039] In addition to the amount and direction of roller deflection, the nip rollers 201, 202 can be controlled individually by rotating only the eccentric bushings associated with each individual roller. This allows the user to further control the distance between the rollers and thus the thickness of the film passing between the rollers. The direction of rotation is not limited, and each of the eccentric bushings 101, 102 can be rotated separately by any desired amount. Furthermore, each individual eccentric bearing associated with a specific nip roller can be adjusted, allowing additional control over the deflection of each roller.

[0040] In some embodiments, the nip rollers 201, 202 have a crown, which serves to further increase the accuracy and precision the rollers exert on an electrode film 613. The crown ensures that the contact area, and thus the film profile and thickness, remain flat and accurate when the roller is deflected or otherwise manipulated. The height of the crown is not limited and is selected depending on the requirements of a particular film and the deflection selected for each roller. In some embodiments, the pressure roller has a crown of about 3 µm, about 4 µm, about 5 µm, about 6 µm, about 7 µm, about 8 µm, about 9 µm, about 10 µm, or any range of the above values, such as about 3 µm to about 10 µm, about 4 µm to about 9 µm, or about 4 µm to about 8 µm.

[0041] The film 613 formed by the nip rolls 201, 202 is not limited and can be a metal, a polymer, a paper, a ceramic, or a mixture or laminate of one or more of the above. In certain embodiments, the film is formed from a dry powder, which is then molded into part of a Li-ion cell. If the film is formed from a dry powder, it is formed into a cathode or an anode for battery cell construction.

[0042] In addition to adjusting the nip 210 between the nip rollers 201, 202 to control film thickness, the nip rollers 201, 202 and the pretensioners 100 can also be used to adjust the pressure exerted on the film. The magnitude of the force applied by the first nip roller 201 or the second nip roller 202, which is attributable solely to the adjustments made by the eccentric bearings, can be up to about 75 kN, up to about 50 kN, up to about 25 kN, about 1 kN to about 75 kN, about 1 kN to about 50 kN, about 10 kN to about 50 kN, about 10 kN to about 40 kN, about 10 kN to about 30 kN, or any combination of one or more of the aforementioned ranges, without the need for external structures or devices. In this way, the first squeezing roller 201 and the second squeezing roller 202 can each be adjusted independently and exert a significant pressure on a powder or film.It is assumed that the aforementioned pressure is only due to the adjustments made by the double eccentrics 99 and that the first nip 210 and the second nip 210 may each exert additional force based on other structures in the device.

[0043] Alternatively, the accuracy of the double eccentric 99 and the associated nip roll 201, 202 is measured by the uniformity of the film 613 formed by the nip roll 201, 202. In some embodiments, a cathode or anode film formed by the nip roll 201, 202 has a measured thickness that varies by no more than about 10 µm, no more than about 8 µm, no more than about 6 µm, no more than about 4 µm, no more than about 3 µm, no more than about 2 µm, no more than about 1 µm, about 1-10 µm, about 1-8 µm, about 1-6 µm, about 1-4 µm, about 1-3 µm, or about 1-2 µm. The above values ​​are measured across the width of the film required for the form factor of the battery cell to be manufactured.

[0044] For each of the preceding paragraphs describing the crown of the nip roll, the force exerted on the nip rolls, and the accuracy of the eccentric bearing and associated nip rolls as measured by film uniformity, these values ​​are in turn measured relative to the width required for the form factor of the cells, such as Li-ion cells, to be produced using the device. Examples of form factors are not limited and include cylindrical cells 10440 or 1044 (10 mm diameter and 44 mm length), 14500 or 1450 (14 mm diameter and 50 mm length), 16340 or 1634 or CR123A (16 mm diameter and 34 mm length), 18650 or 1865 (18 mm diameter and 65 mm length), 21700 or 2170 (21 mm diameter and 70 mm length), 26650 or 2665 (26 mm diameter and 65 mm length), 32650 or 3265 (32 mm diameter and 65 mm length) and 4680 (46 mm diameter and 80 mm length).Prism and pouch cells are also conceivable, although there is no limit to the dimensions considered.

[0045] The disclosed device may further include one or more position sensors connected to the eccentric bearings 99, the nip rolls 201, 202, or both. The position sensors determine the amount of rotation of the eccentric bearings or the amount of rotation of the nip rolls and provide a digital or analog signal corresponding to that amount of rotation of the nip rolls or the eccentric bearings. Such position sensors are not limited and include potentiometric sensors, capacitive position sensors, or optical position sensors. The optical position sensors may operate with any light, including ultraviolet (UV), visible, or infrared light. In certain embodiments, the light selected for the optical position sensor is a laser with one of the aforementioned bandwidths.

[0046] In yet other embodiments, or in conjunction with the provided position sensors, one or more layer thickness sensors may also be provided. The film thickness sensors are not limited and include optical sensors such as laser sensors. The film thickness sensors determine the thickness of the film formed by the nip rollers by measuring the film thickness at at least one point on the film. In some embodiments, there are one or more film thickness sensors configured to measure the thickness at multiple points across the width of the film. The thickness sensors provide a digital or analog signal corresponding to the film thickness.

[0047] The use of the nip rolls 201, 202 and associated components of the disclosure is not limited, but certain uses are desirable. In some embodiments, production lines are constructed that include the nip rolls of the disclosure along with various other components known to those skilled in the art. The nip rolls are employed to precisely control the thickness of the films produced throughout the production line. Examples of films configured to form or that utilize the nip rolls and associated components of the disclosure include one or more of anode films, cathode films, separator films, current collector films, interlayer films, adhesive films, primer films, or laminates comprising two or more of the films described above.

[0048] The disclosed nip rolls 201, 202 and associated components are disclosed as being useful for forming films from powder, but other applications also exist. For example, it is conceivable that the nip rolls and associated components could form films from liquids or non-Newtonian fluids such as slurries.

[0049] FIGS. 9A und 9B is a representation of a particularly advantageous embodiment of the disclosure. According to FIG. 9A und 9B A calender 10 comprises a first nip roll 201 and a second nip roll 202, which are arranged in close proximity to a powder hopper 904 for receiving powdered electrode material 905. Furthermore, a first backup roll 301 and a second backup roll 302 are arranged on one side of the first nip roll 201 and the second nip roll 202. In use, the electrode material 905, which is typically a powder for a dry electrode, is compressed by the first nip roll 201 and the second nip roll 202, thereby forming a dry electrode film 613. After passing through and being deformed by the pressure exerted by the first nip roll 201 and the second nip roll 202, the dry electrode film 613 wraps around the first calender roll 302 and the second calender roll 401.During the movement of the dry electrode film 613, it is compressed and exerts an equal and opposite force on the first pressure roller 201 and the second pressure roller 202. However, the first nip roller 201 and the second nip roller 202 are subjected to different forces due to friction differences. In the example shown, the first nip roller 201 therefore experiences deflection and must be pretensioned accordingly by the pretensioning device 100 (not shown). The second nip roller 202 is surrounded by the dry electrode 613 and, as shown, exhibits no deflection. The second nip roller 202 therefore does not need to be adjusted to the extent required for the first nip roller 201.

[0050] Therefore, in the process described here and in FIG. 9B In the example shown, the first nip roller 201 and the second nip roller 202 are adjusted by one or more biasing devices 100 such that the magnitude of the adjusting force exerted on the first nip roller 201 is greater than the magnitude of the adjusting force exerted on the second nip roller 202. Accordingly, a uniform and precisely controlled gap is ensured between the first nip roller 201 and the second nip roller 202 as the dry electrode film 613 passes through.

[0051] FIG. 10 shows a sectional view through a squeezing roller 201 and a pretensioning device 100 mounted on the roll neck 205 of the squeezing roller 201. The roller 201 is mounted in a machine frame 500 by means of a roller bearing 700. The machine frame further has a bore 520 with a cylindrical bushing received therein on the end face of the roller 201, 202, in which the roll neck 205 of the squeezing roller 201, 202 is received and mounted in the pretensioning device 100. The pretensioning device 100 comprises a double eccentric 99, which essentially consists of an inner eccentric bushing 102 and an outer eccentric bushing 101. The inner eccentric bushing 102 is inserted into the outer eccentric bushing 101 so that they overlap in sections. The outer eccentric bushing 101 is mounted axially rotatably relative to the cylinder bushing via a first radial bearing 110.The inner eccentric bushing 102 is mounted relative to the outer eccentric bushing 101 via a second axially rotatable radial bearing 120. The roll neck 205 is in turn mounted axially rotatably relative to the inner eccentric bushing 102 via a third radial bearing 130. In the orientation shown, the double eccentric 99 is in its initial position, in which the thick section of the outer eccentric bushing is close to the thin section of the inner eccentric bushing 102 and the thin section of the outer eccentric bushing 101 is close to the thick section of the inner eccentric bushing 102, so that the roll neck is centered and not deflected. The eccentric bushings 101 and 102 are adjustable independently of one another using separate rotating devices.To generate a defined roll bend in the roll center, the double eccentric 99 with the roll neck 205 accommodated therein is deflected relative to the roll bearing 700, so that the distance between the double eccentric 99 and the roll bearing 700 acts as a lever arm.

[0052] The features of the invention disclosed in the above description, in the drawings and in the claims may be essential for the realization of the invention both individually and in any combination. Bezugszeichenliste

[0053] 10 Calender 100 Pretensioning device 99 Double eccentric 101 Outer eccentric bushing 102 Inner eccentric bushing 110 First radial bearing 120 Second radial bearing 130 Third radial bearing 201 First nip roll 202 Second nip roll 205 Roll neck 206 Calendering section 210 Roll gap 301 First backup roll 302 Second backup roll 303 Separator film 401 Calender roll 500 Machine frame 520 Bore 613 Electrode film 700 Roll bearing 904 Powder hopper 905 Powdered electrode precursor material D1 Roll diameter D2 Backup roll diameter F Force vector X Deflection direction

Claims

1. A calender (10) for producing an electrode film (613) from a powder-type electrode precursor material (905), having at least a first and a second nip roll (201, 202), rotating in the opposite direction to the first, between which a nip (210) is formed, wherein the calender (10) is configured to apply shear forces to the powder-like electrode precursor material (605) as it passes through the nip (210) and to thereby form an electrode film (613), wherein the first and second nip roll (201, 202) are supported by a respective roll bearing, wherein at least one of the first or second nip rolls (201, 202) has at least one pretensioning device (100) for pretensioning the nip roll (201, 202) against a non-axial, in particular radial and / or tangential, force vector (F) which is generated in the nip (210) by the compression process and which acts on the respective nip roll, by means of which the pretensioning direction (100) and / or the value of the pretensioning force is adjustable, characterized in that the pretensioning device (100) has a double eccentric (99), the double eccentric (99) having an inner eccentric bushing (102) and an outer eccentric bushing (101) which can be rotated independently of one another, the roll bearing being arranged on the nip roll (201, 202), lying further in the direction of the roll center and axially spaced apart from the double eccentric (99), so that the double eccentric (99), in cooperation with the associated roll bearing, effects a bending of the nip roll (201, 202).

2. The calender (10) according to claim 1, wherein both nip rolls (201, 202) are each mounted in a machine frame (500) via their front roll journals (205), wherein the pretensioning device (100) is assigned to at least one bearing (700) of the first or the second nip roll (201, 202), wherein by means of the pretensioning device (100) the roll journal (205) can be deflected radially in any direction and in an adjustable order of magnitude in relation to the at least one bearing (700).

3. The calender (10) according to any of the preceding claims, wherein the first or the second nip roll (201, 202) is rotatably mounted in the inner eccentric bushing (102).

4. The calender (10) according to any one of the preceding claims, wherein the outer eccentric bushing (101) is rotatably mounted relative to a bore (520) arranged in the machine frame (500), in which the pretensioning device (100) is received, wherein optionally a first radial bearing (110) is formed or arranged between the bore (520) and the outer eccentric bushing (101).

5. A calender (10) according to any one of the preceding claims, wherein (i) a second radial bearing (120) is formed or arranged between the outer eccentric bushing (101) and the inner eccentric bushing (102); and / or (ii) a third radial bearing (130) is formed or arranged between the inner eccentric bushing (102) and the roll journal (205).

6. The calender (10) according to any one of claims 4 or 5, wherein the first and / or the second and / or the third radial bearing (110, 120, 130) is designed as a cylindrical roll bearing or as a needle bearing.

7. The calender (10) according to any one of the preceding claims, wherein a first support roll (301) is arranged adjacent to the first nip roll (201) and a second support roll (302) is arranged adjacent to the second nip roll (202), which each rotate in the opposite direction to the latter.

8. The calender (10) according to claim 7, wherein (i) the support rolls (301, 302) have a larger diameter (D2) than the first and second nip rolls (201, 202); (ii) the axes of the nip rolls (201, 202) and of the support rolls (301, 302) are aligned in a plane with one another; and / or (iii) the first nip roll (201) and the first support roll (301) roll on one another and a nip (210) for passage of the electrode film (613) is formed between the second nip roll (202) and the second support roll (302), wherein the second nip roll (202) is designed to guide the electrode film (613) around the upper or lower side of the second nip roll (202).

9. The calender (10) according to any one of the preceding claims, wherein a device (904) for continuously conveying powder-like electrode precursor material (905) into the roll nip (210) is arranged above the roll nip (210) between the first and second nip rolls (201, 202).

10. The calender (10) according to any one of the preceding claims, wherein at least one of the first or second nip rolls (201, 202) has a pretensioning device (100) on each of its opposite roll journals (205).

11. The calender (10) according to any one of the preceding claims, wherein both the first and the second nip rolls (201, 202) have a respective pretensioning device (100) on each of their opposite roll journals (205).

12. A method for producing an electrode film (613) having a homogeneous thickness from a powder-like electrode precursor material (905), comprising the following steps: conveying powder-like electrode precursor material (905) into a nip (210) formed by two nip rolls (201, 202), wherein each nip roll (201, 202) is supported by a respective roll bearing; passing the powder-like electrode precursor material (905) through the nip (210), wherein the powder-like electrode precursor material (905) is subjected to shear forces as it passes through the nip (210), so that an electrode film (613) is formed; applying a pretensioning on at least one of the two nip rolls (201, 202) to counteract a force vector (F) resulting from the passage of the powder-like electrode precursor material (905) through the nip (210) on the respective nip roll, wherein the pretensioning comprises radially deflecting at least one roll journal (205) of the respective nip roll (201, 202), wherein the radial deflection of the at least one roll journal (205) comprises relatively and / or uniformly rotating a double eccentric (99) provided on the roll journal (205), wherein the roll bearing is arranged on the roll further in the direction of the roll center and is at an axial distance from the double eccentric (99), so that the double eccentric (99), in cooperation with the associated roll bearing, causes the nip roll (201, 202) to bend.

13. The method according to claim 12, wherein the radial deflection comprises the deflection of two opposite roll journals (205) of at least one of the nip rolls (201, 202), wherein both roll journals (205) are deflected radially in the same direction.

14. The method according to any one of claims 12 or 13, wherein the radial deflection comprises the respective deflection of two opposing roll journals (205) of both nip rolls (201, 202), wherein the opposing roll journals (205) are each deflected in the same direction and the roll journals (205) of the first and the second nip roll (201, 202) are deflected in the same or in the diametrically opposite direction.

15. The method according to any one of claims 12 to 14, further comprising: supporting of both nip rolls (201, 202) on the respective sides of the nip rolls (201, 202) facing away from the nip (210) by means of a line force respectively acting radially on the nip rolls (201, 202).