Method for manufacturing electrodes for battery cells, apparatus for manufacturing electrodes for battery cells, and battery

Abstract

To provide an advantageous method for fabricating an electrode for a battery cell, an advantageously formed apparatus for fabricating an electrode for a battery cell, and an advantageously formed battery.SOLUTION: A method for fabricating an electrode for a battery cell includes coating a material tape (4) on at least a first side (14) with a coating material (6), and applying the coating material (6) to the first side (14) by a first application roll (10).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an electrode for a battery cell. Furthermore, the present invention relates to an apparatus for manufacturing an electrode for a battery cell, and the present invention relates to a battery.

[0002] Batteries, such as lithium-ion batteries, are currently widespread. Batteries are used particularly in motor vehicles, where, for example, they are used as so-called traction batteries, i.e., energy storage devices for supplying power to an electric drive machine.

[0003] Corresponding batteries often have a plurality of battery cells connected to one another. These battery cells are usually formed substantially uniformly. Particularly in lithium-ion batteries, each battery cell typically has two electrodes, one separator, and one electrolyte.

[0004] Based on this, the underlying problem of the present invention is to provide an advantageous method for manufacturing an electrode for a battery cell, an advantageously formed apparatus for manufacturing an electrode for a battery cell, and an advantageously formed battery.

[0005] This problem is solved by a method having the features of claim 1, an apparatus having the features of claim 9, and a battery having the features of claim 10. Preferred configurations and improvements are the subject of the dependent claims. The advantages and configurations described with respect to the method can be similarly transferred to the apparatus and / or the battery, and vice versa.

[0006] The method according to the present invention is used for and is designed for the purpose of fabricating electrodes for battery cells. The method, that is, the method according to the present invention, is preferably carried out by an apparatus according to the present invention. The apparatus itself is formed and configured to fabricate electrodes for battery cells by the method according to the present invention. In this case, by using the method, electrodes for battery cells, more preferably battery cells, in particular batteries according to the present invention, are fabricated. Each battery, that is, each battery according to the present invention, has at least one battery cell having at least one electrode fabricated by the method according to the present invention.

[0007] However, in most cases, the battery according to the present invention has a plurality of battery cells connected to one another. These battery cells are usually formed substantially uniformly. Each battery cell conveniently has two electrodes, one separator, and one electrolyte. Furthermore, the battery is preferably formed as a lithium-ion battery. Depending on the use case, the battery is designed for use in, for example, automobiles, that is, as an energy storage device for supplying power to, for example, electric drive machinery.

[0008] In order to manufacture electrodes for battery cells, a coated material tape is produced when carrying out the method according to the present invention. Therefore, processing of the material tape is performed when carrying out the method, that is, the method according to the present invention.

[0009] Such material tapes are typically ready-made strips. These strips usually have or are formed from metal foil, such as copper foil or aluminum foil. Furthermore, material tapes typically exist as so-called endless materials or roll materials. Material tapes have a length that is sufficiently larger than their width, thickness, or height. Material tapes preferably have a width of 400 mm or more, especially 500 mm or more, i.e., a width of 600 mm.

[0010] During processing, the material tape is coated with a coating material on at least one surface. This coating material contains an active material, i.e., a so-called electrode active material or simply electrode material. In this case, the corresponding active materials are known in principle. Examples of active materials for forming the negative electrode are graphite and silicon. Examples of electrode materials for forming the positive electrode are NMC (lithium-nickel-manganese-cobalt oxide), LFP (lithium iron phosphate), and NCA (lithium-nickel-cobalt-aluminum oxide). Depending on the application, the coating material may further contain a so-called binder and / or a so-called conductive additive.

[0011] The coating material is applied to or deposited onto a first surface by a first adherend roll. In this case, in particular, a direct transfer of the coating material from the first adherend roll to the material tape occurs. Therefore, in this case, the coating material is roll-applied to the material tape, so to speak.

[0012] The first adherend roll is typically supplemented by a corresponding roll. During operation, the first adherend roll and the corresponding roll usually rotate in opposite directions. In this example, for coating, a material tape is guided between the first adherend roll and the corresponding roll, and the coating material is applied or deposited onto the first surface of the material tape by the first adherend roll in the intermediate space between the first adherend roll and the corresponding roll.

[0013] Subsequently, the coating of the material tape, that is, the application or deposition of the coating material to the material tape, is preferably carried out without a solvent, that is, in particular without a liquid solvent. In other words, the preparation of a suspension having, for example, an active material and a liquid solvent is preferably omitted. Based on the omission of the liquid solvent, the method described herein is also called dry electrode fabrication or, in fact, solvent-free electrode fabrication.

[0014] Furthermore, the coating material exists as a powder or powder mixture, and a method of application or application to the first adherend roll is particularly preferred, in which case it is applied or applied as a powder. It is also advantageous that the coating material applied to the first adherend roll is subsequently densified. Densification is preferably performed before applying or applying the coating material to the material tape.

[0015] In particular, a modified method in which the coating material is densified on the first adherend roll by the first pressing roll is advantageous. Therefore, in this case, the first adherend roll is supplemented by the first pressing roll. During operation, the first adherend roll and the first pressing roll usually rotate in opposite directions to each other. In this example, the coating material is guided through the space between the first adherend roll and the first pressing roll, and the coating material is densified in the intermediate space between the first adherend roll and the first pressing roll.

[0016] Furthermore, it is advantageous that the coating material is applied to a first surface of the material tape over a predetermined first coating width. The first coating width corresponds to a specific width of the coating on the first surface of the material tape, i.e., a specific extending length of the coating in the transverse direction relative to the longitudinal direction of the material tape.

[0017] A specific extension length of the coating material transverse to the longitudinal direction is more preferably preset on the first adherend roll, and thus typically preset before the coating material is applied to the material tape. More preferably, the specific extension length of the coating material transverse to the longitudinal direction is preset by reducing the extension length of the coating material transverse to the longitudinal direction on the first adherend roll to a preset first coating width. That is, the coating material is usually first applied to the first adherend roll with a provisional extension length transverse to the longitudinal direction, and then this provisional extension length is reduced to a first coating width. In this case, it is advantageous that the provisional extension length transverse to the longitudinal direction is greater than the first coating width. Furthermore, it is advantageous that the provisional extension length is reduced to a first coating width by at least one mechanical element, i.e., a mechanical element acting particularly as a cutter and / or scraper.

[0018] Preferably, the first coating width is preset by a score cutter, and more particularly by pressing against the first adherend roll. The corresponding score cutter is typically, for example, a cutter disc having a wedge-shaped cutting edge. In this case, such a cutter disc preferably contacts the first adherend roll and pushes the coating material apart from each other along specific edges.

[0019] In an advantageous improved configuration, the pressure applied to the score cutter when it contacts the first adherend roll is preset. Depending on the implementation, this pressure may be preset using, for example, a spring element. Alternatively, the pressure may be preset via a pneumatic device and thus pneumatically adjustable.

[0020] Furthermore, it is advantageous if the first coating width is predetermined by a scraper that scrapes the coating material from the first adherend roll. In particular, it is preferable that this scraper complements the aforementioned score cutter, so that any excess coating material separated by the score cutter is scraped off from the first adherend roll by the scraper.

[0021] Furthermore, a configuration in which two score cutters of the aforementioned form are used for setting the first coating width is advantageous. In this case, both score cutters are conveniently spaced apart from each other when viewed in the direction of the longitudinal axis of the first workpiece roll. In this case, the distance between the two score cutters pre-sets the first coating width. Furthermore, in an advantageous improved form, a scraper of the aforementioned form is placed alongside each of the two score cutters.

[0022] In other words, according to the method described herein, preferably, the coating material is first applied to a first adherend roll over a width greater than a specific width of the coating on a first surface of the material tape. Subsequently, the width on the first adherend roll is reduced to a first coating width, and finally the coating material is applied to the material tape with a first coating width.

[0023] The reduction, if advantageous, allows for precise adjustment of the coating width, i.e., a type of edge trimming. The reduction is preferably carried out by push-cutting, i.e., by the aforementioned score cutter. Corresponding to alternative forms of modification, the reduction is carried out by so-called kiss-cutting or roll punching.

[0024] Furthermore, for reduction purposes, it is advantageous to use cutters equipped with square blades (razor blades). Alternatively, round cutters, for example, that are driven or dragged, can be used.

[0025] Regardless of this, preferably, the distance between the first application roll and the cutter used is adjusted with micrometer accuracy, and thus, is preset with micrometer accuracy.

[0026] Furthermore, when the width reduction described above occurs, typically, the coating material is dissociated from the first application roll again. Subsequently, the coating material dissociated from the first application roll is preferably collected or sucked up so as not to fall without particular control. It is convenient if the collected or sucked-up coating material is reused.

[0027] Furthermore, the material tape typically has the first surface described above and a second surface on the opposite side. Depending on the use case, in addition to the first surface, the second surface is also coated with the coating material in the form described above, particularly the same coating material as the first surface.

[0028] Conveniently, the coating material is applied to the second surface of the material tape by a second application roll. In this case, in this instance, typically, this second application roll also functions as the corresponding roll to the first application roll described above, and the first application roll similarly functions as the corresponding roll to the second application roll.

[0029] Furthermore, the second application roll is also preferably supplemented by a pressing roll, that is, a second pressing roll. In this case, similar to the first pressing roll, the coating material, and moreover, the coating material on the second application roll is densified by the second pressing roll.

[0030] Furthermore, it is advantageous if the coating material is applied to the second surface of the material tape over a preset second coating width. The setting of the second coating width is preferably performed in the same manner as the form described above with respect to the first coating width.

[0031] In summary, or rather, this specification describes a concept that enables electrode fabrication, especially solvent-free or dry electrode fabrication. In this case, the following are particularly important. - Electrode fabrication is preferably carried out by a plurality of rolls, especially a plurality of calendar rolls. Typically, to form a coating, at least one roll-supported electrode film made of a coating material is applied to a strip. The application is typically carried out within a calendar nip between two rolls. - Further, this concept enables, preferably, accurate setting / accurate adjustment of the coating width. For this, each electrode film edge is preferably formed by die-cutting. Each die-cutting is typically carried out directly on one of the plurality of rolls, thereby ultimately obtaining an accurate coating width with a qualitatively high-value coating edge that remains unchanged. More preferably, each die-cutting is supplemented by a doctor process for removing excess coating material at the electrode film edge. - Further, the excess coating material is preferably collected directly in a container or absorbed and conveyed into a separate container. From there, the excess coating material is preferably directly supplied again to one of the preceding plurality of process steps (direct recycling). - The position and pressing force of the score cutter and doctor used are preferably variably adjusted according to process requirements. For this, according to a preferred configuration, pneumatic control is used to ensure a constant pressing force and position. - As an option, optical edge recognition of the coating width is provided. Further, this edge recognition enables accurate positioning of the score cutter and doctor, preferably via closed-loop control. - In alternative implementations of the method, instead of a push cut, a so-called kiss cut is used, similar to roll punching, where the cutter has a specified gap of several micrometers relative to the corresponding object (calendar roll). In this case, a square blade (razor) or a round cutter is used (either driven or dragged). - As an alternative to pneumatic pressing, a mechanical pressing method using a spring element is provided.

[0032] The concept offers the following advantages depending on the form of implementation: - By using a pneumatic press cutter to cut against the roll / calendar roll, the cutting force can be precisely adjusted. - Pneumatic pressure allows for a constant pressing force that is precisely adjustable and controllable. - The cutting position can be precisely and reproducibly adjusted, and the detached ears can be directly removed from the roll / calendar roll by the associated scraper / doctor. - The press-cutting method ensures reproducibly adjustable cut edge quality with a specified pressing force. - The use of KissCut has the advantage of eliminating contact between the cutter and the roll. This extends the blade life and reduces wear on the calendar roll (run marks). - Depending on the method, the coating edges can be precisely positioned, allowing the product to be manufactured to the required quality. - Excess material can be removed and directly supplied again to the preceding process step.

[0033] In other words, as described above, when carrying out the method according to the present invention, a coated material tape is produced. The production of this coated material tape is conveniently carried out as a step in a method for producing electrodes for battery cells. This step is preferably carried out by a processing station which is part of the apparatus according to the present invention for producing electrodes for battery cells.

[0034] Subsequently, conveniently, in a later step of the method, the coated material tape is cut. In this case, the electrodes are completely separated or detached. The subsequent step is preferably carried out by another processing station of the apparatus according to the present invention.

[0035] Further advantages, features, and details of the present invention will become apparent from the claims, the following description of preferred embodiments, and the schematic drawings. [Brief explanation of the drawing]

[0036] [Figure 1] This is a side view of a device for manufacturing electrodes for battery cells. [Figure 2] This is a view of the device from below.

[0037] In all drawings, corresponding components are denoted by the same reference numeral.

[0038] The method described below is used to manufacture electrodes for battery cells. The method has two steps: a coating step and a cutting step. In the coating step, a pre-made material tape 4 is coated with a coating material 6, for example, graphite, to produce a coated material tape 2. Then, in the cutting step, the coated material tape 2 is cut, and the electrodes are completely separated or detached.

[0039] The coating process is described in detail below. The coating process is carried out by apparatus 8, which is shown in a simplified form in Figures 1 and 2. Apparatus 8 is shown in a side view in Figure 1 and in a view from below in Figure 2.

[0040] In this embodiment, the apparatus 8 has two adherend rolls 10 and 12, namely a first adherend roll 10 and a second adherend roll 12. During operation of the apparatus 8, the coating material 6 is applied to the first surface 14 of the material tape 4 by the first adherend roll 10. In this case, a direct transfer of the coating material 6 from the first adherend roll 10 to the material tape 4 occurs. Therefore, the coating material 6 is, so to speak, roll-coated onto the material tape 4. Similarly, the coating material 6 is applied to the second surface 16 of the material tape 4 by the second adherend roll 12. In this case as well, the coating material 6 is, so to speak, roll-coated onto the material tape 4.

[0041] The two adherend rolls 10 and 12 together form a single roll pair. The two adherend rolls 10 and 12 are positioned with a small gap between them and rotate in opposite directions during operation. At this time, the material tape 4 is passed between the two adherend rolls 10 and 12 and coated on both sides with the coating material 6 in the intermediate space between these two adherend rolls 10 and 12. Thus, the two adherend rolls 10 and 12 act like a so-called calendar roll.

[0042] The material tape 4 is typically a pre-fabricated strip. This strip is usually formed from a metal foil, such as copper foil or aluminum foil. The material tape 4 is supplied, so to speak, continuously to two adherend rolls 10 and 12, preferably as a so-called endless material or roll material.

[0043] The coating material 6, which is applied to the material tape 4 from the adhering rolls 10 and 12, is first applied to the adhering rolls 10 and 12. For this purpose, supply units 18 and 20 are assigned to each of the adhering rolls 10 and 12. The coating material 6 exists as a powder in these supply units 18 and 20 and is also applied to the adhering rolls 10 and 12 in powder form. Therefore, the use of a liquid solvent for adhesion is omitted.

[0044] In other words, the coating material 6 is applied as a powder, and then densified to form a film 22. This film 22 adheres to each of the adherend rolls 10 and 12, and is then transferred to the material tape in the intermediate space between the adherend rolls 10 and 12. This process is carried out on both adherend rolls 10 and 12.

[0045] Densification is performed by two pressing rolls 24 and 26. The first pressing roll 24 is assigned to the first workpiece roll 10, and the second pressing roll 26 is assigned to the second workpiece roll 12. In both cases, the workpiece rolls 10 and 12 and their respective assigned pressing rolls 24 and 26 form a roll pair. In this roll pair, the rolls are positioned with a small gap between them and rotate in opposite directions during operation.

[0046] Furthermore, in this embodiment, two score cutters 28 are assigned to each of the workpiece rolls 10 and 12, and one scraper 30 is placed next to each score cutter 28. Therefore, the device 8 has four score cutters 28 and four scrapers 30.

[0047] The two score cutters 28 on each adherend roll 10, 12 are spaced apart from each other when viewed in the direction of the longitudinal axes 32, 34 of the corresponding adherend rolls 10, 12. In this case, the appropriate spacing between the two score cutters 28 sets the respective widths of the coatings, i.e., the first coating width 36 on the first surface 14 of the material tape 4 and the second coating width 38 on the second surface 16 of the material tape 4. That is, edges are formed by cutting with each score cutter 28. These edges first define the respective films 22 on each adherend roll 10, 12, thereby ultimately defining the width of each coating on each surface of the material tape 4.

[0048] As is clear from Figure 2, in this embodiment, a uniform width is predetermined for the coating on the two surfaces 14 and 16 of the material tape 4, and consequently, the first coating width 36 on the first surface 14 of the material tape 4 corresponds to the second coating width 38 on the second surface 16 of the material tape 4.

[0049] Any excess coating material 6 that extends beyond each edge is scraped off from the respective adherend rolls 10 and 12 by the juxtaposed scrapers 30. Preferably, the scraped coating material 6 is then supplied again to supply units 18 and 20 (detailed illustration omitted) and ultimately reused.

[0050] As shown in Figure 1, the apparatus 8 preferably further includes at least one optical sensor 40. This sensor 40 generates sensor data representing, for example, the coating on the second surface 16 during operation. This sensor data is then preferably evaluated by the control and evaluation unit 42 of the apparatus 8. This allows for monitoring of the coating width, for example, by optical edge recognition. Subsequently, according to an advantageous improved embodiment, the instantaneous coating width is determined and compared with a target value. More preferably, control is then performed, for example, via closed-loop control that tracks the positioning of the score cutter 28 and the scraper 30. [Explanation of symbols]

[0051] 2. Tape made of coated material 4. Material Tape 6. Coating materials 8 equipment 10. First attachment roll 12. Second attachment roll 14. The first side 16. The second side 18. First supply unit 20 Second supply unit 22 film 24 First pressing roll 26. Second pressing roll 28 Score Cutter 30 Scrapers 32 First longitudinal axis 34 Second longitudinal axis 36 First coating width 38 Second coating width 40 sensors 42 Control and Evaluation Units

Claims

1. A method for manufacturing electrodes for a battery cell, comprising: coating a material tape (4) with a coating material (6) on at least a first surface (14); and adhering the coating material (6) to the first surface (14) with a first adhering roll (10); The coating material (6) is applied to the first surface (14) over a predetermined first coating width (36), and the first coating width (36) is set before application by a score cutter (28) provided on the first application roll (10). method.

2. The method according to claim 1, wherein the coating material (6) is applied without a solvent.

3. The method according to claim 1, wherein the coating material (6) is applied to the first adherend roll (10) as a powder.

4. The method according to claim 1, wherein the coating material (6) applied as a powder is densified on the first adherend roll (10).

5. The method according to claim 4, wherein the coating material (6), which has been applied as a powder, is densified by the first pressing roll (24) while the coating material (6) is passed between the first adherend roll (10) and the first pressing roll (24).

6. The method according to claim 1, wherein the pressing pressure of the score cutter (28) is adjusted by air pressure.

7. The method according to claim 1, wherein the coating material (6) is applied to the first surface (14) over a predetermined first coating width (36), and the first coating width (36) is predetermined by a scraper (30) that scrapes the coating material (6) from the first application roll (10).

8. An apparatus (8) configured to manufacture electrodes for battery cells by the method described in any one of claims 1 to 7.

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