Method for manufacturing an electrode, electrode, electrode stack, energy storage device, and traction battery

Abstract

The present invention relates to a method for manufacturing an electrode, in particular for a lithium-ion battery, the method comprising the following steps: cladding a carrier material; processing the carrier material for producing at least one monolithic piece which does not have uncladded areas or has only uncladded areas which are dimensioned such that no wrinkles or cracks occur during pressing, compressing or rolling; adjusting the porosity of the electrode on the monolithic piece by pressing and / or rolling, wherein rolling is carried out in different directions. The present invention also relates to an electrode, an electrode stack, an energy storage device and a traction battery.

Description

Field of the Invention

[0001] The present invention relates to a method for manufacturing an electrode for an accumulator cell, in particular for a lithium-ion battery or lithium-ion accumulator, an electrode, an electrode stack, an accumulator, and a traction battery. Background Art

[0002] The electrode is in particular a single-piece electrode as used in an electrode stack. The electrode is formed by a coated film. After coating and drying, the electrode is compressed (e.g., by a calendering process), cut to a target width (e.g., cut using a roll shearing machine), and then separated into single pieces after performing contour cutting and optionally stacked. A problem that often occurs during calendering is that undesired deformations occur in all regions of the film. In particular, in the uncoated region of the carrier film, wrinkles are generated due to force introduction, which leads to a decrease in quality and also makes further processing of the film difficult. Therefore, cracks, corrugations, etc. may be formed in downstream process steps, such as when cutting the film, due to pre-damage. Film cutting by means of a laser may also become difficult because proper focusing cannot be achieved. To address these problems, EP 2 296 209 A1 proposes heating the uncoated region of the carrier film. DE 10 2017 215 143 A1 uses a metal film that has a bend in the web plane when the metal film is unfolded in the web plane. This bend is removed by applying pressure accordingly during calendering, and the above-mentioned undesired deformation effects should not exist in the final material. However, the known solutions are very costly and time-consuming in manufacturing technology. Summary of the Invention

[0003] Therefore, the object of the present invention is to provide a method for manufacturing an electrode, an electrode, an electrode stack, an accumulator, and a traction battery that do not have the above problems.

[0004] The object is solved by a method according to the invention, an electrode according to the invention, an electrode stack according to the invention, an accumulator according to the invention, and a traction battery according to the invention.

[0005] According to the invention, a method for manufacturing an electrode, in particular a composite electrode, in particular an electrode for an accumulator cell (e.g., a lithium-ion cell) comprises the following steps:

[0006] - Coating a carrier material for manufacturing or producing an electrode, in particular coating with a coating material;

[0007] - Process the carrier material for producing at least one monolithic piece that has no uncoated areas on at least three edges, where the monolithic piece has no uncoated areas or has only partially uncoated areas extending along one edge, and the uncoated areas are dimensioned such that no wrinkles or cracks occur during pressing, compressing, or rolling;

[0008] - Adjust the porosity of the electrode on the monolithic piece by pressing and / or rolling, where rolling is performed along different directions.

[0009] Thus, the traditional process chain is advantageously improved. According to the process chain, the carrier material is first coated, and then the carrier material is compressed to adjust the porosity. The carrier material is coated with a coating material, especially on one side or on both sides. According to one embodiment, the coating material includes an active material, an electrode binder, conductive carbon black (optionally conductive graphite), and a carrier solvent. However, the porosity of the electrode is compressed or adjusted only after the carrier material (such as a carrier material in the form of a metal film) has been cut according to the area of the monomer. The carrier material is especially a carrier film. The material of the carrier film is selected accordingly depending on whether the electrode is an anode or a cathode electrode. In the case of an anode, the carrier film is typically a copper film, and in the case of a cathode, the carrier film is typically an aluminum film. The preferred film thickness fluctuates, for example, between 6 µm and 25 µm according to the monomer design. Preferably, the aluminum film is rolled. Preferably, the copper film is rolled or electrolytically manufactured. The carrier film is not limited, but the carrier film can also be a punched film or a wire mesh in any geometric structure. The carrier material or the carrier film is coated on one side or on both sides. This is carried out, for example, with a suitable coating tool such as a slot nozzle, a doctor blade, a gravure roll, etc. Alternatively, the carrier material can also be a plastic film, which is coated in a suitable manner, for example, with metal. By adjusting the porosity of the electrode on the monolithic piece, the above-mentioned disadvantages or problems, such as the formation of cracks, wrinkles, etc., are eliminated.

[0010] Preferably, the electrode is configured as a cathode or an anode for a lithium-ion monomer. However, the above-mentioned monomer types are not restrictive. Alternative applications, such as for lithium-sulfur monomers, are also preferred.

[0011] According to one embodiment, the method includes the following steps:

[0012] - Process by cutting or trimming using a thermal cutting process or a mechanical cutting process.

[0013] Preferred mechanical cutting processes are in particular cutting, blanking, granule cutting or water jet cutting. Preferred thermal cutting processes are for example laser cutting. According to one embodiment, the cutting or trimming is carried out close to the final contour. Alternatively, the desired final contour can already be produced, in particular precisely, in this step.

[0014] According to one embodiment, the carrier material is configured in the form of a web or is present in web form. According to one embodiment, the carrier material is coated stripwise and continuously or discontinuously. A plurality of coated strips can also be configured along the web direction of the carrier material. In the case of discontinuous coating, the size of the surface of the coating preferably corresponds precisely or substantially to the size of a single piece.

[0015] According to one embodiment, the method comprises the following steps:

[0016] - Processing the carrier material along the area of the coating.

[0017] Advantageously, in this embodiment, no cutting is carried out through the coating or the coating material, whereby a very neat cutting edge can be produced.

[0018] According to one embodiment, the method comprises the following steps:

[0019] - Forming the outlet body region during processing of the carrier material.

[0020] Desirably, the single piece is formed together with the outlet body region. Advantageously, this step can be carried out such that the outlet body region is not coated. Alternatively, the coating that may be present can also be removed subsequently.

[0021] According to one embodiment, the method comprises the following steps:

[0022] - Forming the outlet body region after adjusting the porosity.

[0023] In this embodiment, the single piece is cut, for example, such that one or two uncoated regions, in particular strips, remain exposed at the edge. This can be advantageous in terms of the processing of the single piece, since these regions (apart from the outlet body region) are removed later. Here, mechanical devices, such as robots etc., can thus be easily attached with grippers. Here, the uncoated regions are advantageously configured so narrow that no problems occur when adjusting the porosity later, for example by rolling.

[0024] According to one embodiment, the method comprises the following steps:

[0025] - Adjusting the porosity by pressing and / or rolling.

[0026] During pressing, the pressure is applied vertically or substantially vertically, i.e., in the normal direction, on one side or on both sides to the single sheet. For this purpose, a corresponding press or pressing punch can be used. Advantageously, very economical processing can be achieved thereby. According to one embodiment, rolling is carried out in a calender.

[0027] According to one embodiment, the method comprises the following steps:

[0028] - Rolling is carried out along different rolling directions.

[0029] The rolling can be carried out, for example, in a calender. Since the traditional Roll-to-Roll process is not involved, mechanical stress is not generated on the electrode or the single sheet by tensile force. Thus, the risk of rupture of the single sheet or the uncoated area is eliminated to a certain extent. According to one embodiment, at least one calender roll is heated to simplify compression.

[0030] Thereby, a higher compaction of the electrode can be achieved particularly advantageously, and thus a higher electrode density can be obtained. Therefore, higher power and higher energy density can be achieved with such an electrode.

[0031] Here, it is particularly advantageous that rolling can also be carried out along different rolling directions or different compression processes can be combined, for example, first compressed with a pressing tool and then compressed in a calender by means of rolling. Here, the aforementioned rolling directions can be, for example, perpendicular or substantially perpendicular to each other to compensate for possible deformations.

[0032] According to one embodiment, the method comprises the following steps:

[0033] - Moving or transporting the single sheet by means of a suction gripper.

[0034] The suction gripper can be used to remove and supply uncoated single sheets and coated single sheets, which can be, for example, stored intermediate in a silo, and the removal and supply can also be automated using a robot.

[0035] According to one embodiment, the method comprises the following steps:

[0036] - Moving or transporting the single sheet by means of a transport film.

[0037] According to one embodiment, the single sheet is guided and positioned on a polyester film. According to one embodiment, the single sheet is also particularly protected, especially mechanically and thermally, between two polyester films.

[0038] According to one embodiment, the method comprises the following steps:

[0039] - The monolithic piece is coated using one of the following processes: lamination, bonding, gluing, extrusion, dry coating, wet coating, direct wet coating, etc.

[0040] A drying process is generally carried out after coating. In the case of wet coating, the so-called carrier solvent (such as water) is removed. Generally, vacuum drying is then carried out, in which the residual humidity in the electrode is reduced.

[0041] According to one embodiment, the method comprises the following steps:

[0042] - The monolithic piece is re-cut after adjusting the porosity.

[0043] According to one embodiment, the final shape of the monolithic piece is manufactured in this step, in other words, the final contour of the monolithic piece is manufactured. As already shown, the method step can also be configured such that the derived body region is constructed together here. For cutting, the mechanical cutting process and / or the thermal cutting process already mentioned are preferably used.

[0044] The invention also relates to an electrode, in particular a composite electrode, which is particularly used for an accumulator cell, a lithium-ion battery or a lithium-ion storage battery. The electrode comprises a carrier material having the size of a monolithic piece, and wherein the carrier material has an uncompressed coating. In particular, it relates to an uncompressed monolithic electrode. The electrode preferably does not have an uncoated area or only has a very small uncoated area. Thereby, the risk of the electrode or the uncoated part on the carrier material breaking no longer exists, and a higher pressing of the electrode can be achieved and thus a higher electrode density can be obtained. It has been shown that such electrodes can be processed very well further.

[0045] The invention also relates to an electrode stack, which comprises a plurality of electrodes, cathodes and anodes arranged in a stacked manner and manufactured according to the method of the invention. For mass production of the electrode stack, the electrodes are used together with separators. All known separators can be mass-produced and applied for the monolithic pieces.

[0046] According to one embodiment, the electrode stack is configured as a monolithic stack. Alternatively, the electrode stack is configured as a dual-cell stack (Bizellenstapel).

[0047] Furthermore, the invention relates to an accumulator, which comprises an electrode stack according to the invention. According to one embodiment, the accumulator is a lithium-ion cell or a lithium-sulfur cell.

[0048] According to one embodiment, the accumulator includes a rigid monolithic housing, which particularly has a prismatic shape. Alternatively, the accumulator can be configured as a pouch or soft pack, where a soft pack made of a high-precision aluminum composite film is involved here. Alternative battery housing shapes are also feasible. In principle, the stacking of the electrodes enables extremely high utilization of an angular, particularly cubic or cuboid battery housing, particularly referring to the aforementioned prismatic battery housing.

[0049] Furthermore, the present invention relates to a traction battery, which includes at least one accumulator according to the present invention. Preferably, the traction battery is designed for use in a motor vehicle, such as a passenger car, a motorcycle or a commercial vehicle. Description of the Drawings

[0050] Other advantages and features are derived from the following description of the method embodiments with reference to the drawings. Different features can be combined with each other within the scope of the present invention.

[0051] In the figures:

[0052] Figure 1 Shows in a schematic diagram an embodiment of the method flow for manufacturing an electrode according to the present invention;

[0053] Figure 2 Shows in a schematic diagram an alternative method flow of an embodiment of the method according to the present invention. Detailed Embodiments

[0054] Figure 1 Two embodiments of the carrier material or carrier film 10 are shown on the left, which extends along the web direction B. The upper variant is coated stripwise, see reference numeral 22, and the lower variant is coated stripwise and discontinuously along the web direction B. The uncoated areas are denoted by reference numeral 26. Compression has not yet been carried out, that is, the porosity of the electrode has not yet been adjusted. As expected, a single sheet is manufactured from this carrier material 10, see reference numeral 20. In the embodiment shown here, the lead-out body region 24 is automatically constructed together here. The adjustment of the porosity of the electrode, or compression or pressing, is carried out only in a subsequent step, that is, advantageously directly on the single sheet 20. Reference numerals W1 and W2 exemplarily denote two rolling directions. Compression in different directions improves process stability because possible deformations can be compensated as well as possible. After pressing or compressing the electrode, in a final step, the single sheet 20 is cut into the final contour if necessary. According to the embodiment, this step can also be omitted. In the case where the lead-out body region 24 is coated, the lead-out body region can also be exposed subsequently.

[0055] Figure 2 shows an alternative embodiment of a method for manufacturing an electrode, wherein the main steps are Figure 1 known. A decisive difference is that here, when manufacturing the monolithic body 20 from the carrier film 10, the lead-out body region 24 is not already produced together. Instead, the lead-out body region 24 is only produced in the final processing step. The monolithic body 20 first has a strip-shaped uncoated region 26. This region can advantageously be used for better handling of the monolithic body 20 during the process. Here, the uncoated region 26 is dimensioned so small that no wrinkles, cracks, etc. occur during pressing, compressing or rolling.

[0056] List of reference numerals

[0057] 10 Carrier material, carrier film

[0058] 20 Monolithic body

[0059] 22 Coating, coating material

[0060] 24 Lead-out body region

[0061] 26 Uncoated region

[0062] W1 First rolling direction

[0063] W2 Second rolling direction

[0064] B Web direction

Claims

1. A method for manufacturing an electrode for an accumulator cell, the method comprising the following steps: - Clad the carrier material (10); - Process the carrier material for producing at least one monolithic piece (20) that has no uncoated area on at least three edges, where the monolithic piece has no unclad area or has an unclad area that only partially extends along one edge, and the unclad area is dimensioned such that no wrinkles or cracks occur during pressing, compressing, or rolling; - Adjust the porosity of the electrodes on the monolithic piece (20) by pressing and / or rolling, where rolling is performed along different directions (W1, W2).

2. The method according to claim 1, wherein, The method comprises the following steps: - Process by cutting or trimming using a thermal cutting process or a mechanical cutting process.

3. The method according to claim 1 or 2, wherein, The carrier material (10) is only locally clad, and the method comprises the following steps: - Process the carrier material (10) along the clad area.

4. The method according to claim 1 or 2, wherein, The method comprises the following steps: - Form the lead-out body area (24) during processing of the carrier material (10).

5. The method according to claim 1 or 2, wherein, The method comprises the following steps: - Form the lead-out body area (24) after adjusting the porosity.

6. The method according to claim 1 or 2, wherein, The method comprises the following steps: - Move the monolithic piece (20) by means of a suction gripper.

7. The method according to claim 1 or 2, wherein, The method comprises the following steps: - Move or transport the monolithic piece (20) by means of a transport film.

8. The method according to claim 1 or 2, wherein, The method comprises the following steps: - Re-cut the monolithic piece (20) after adjusting the porosity.

9. The method according to claim 1 or 2, wherein, The method comprises the following steps: - Clad the monolithic piece (20) by a process selected from at least one of the following processes: lamination, bonding, gluing, extrusion, dry cladding, wet cladding.

10. The method according to claim 1 or 2, wherein, The method comprises the following steps: - Clad the monolithic piece (20) by a process selected from at least one of the following processes: lamination, bonding, gluing, extrusion, dry cladding, direct wet cladding.

11. An electrode comprising a carrier material (10) having a monolithic size, and the carrier material (10) having an uncompressed coating, the electrode having no uncoated areas on at least three edges, wherein, The electrodes have no unclad area or have an unclad area that only partially extends along one edge, and the unclad area is dimensioned such that no wrinkles or cracks occur during pressing, compressing, or rolling.

12. An electrode stack comprising a plurality of electrodes stacked, the electrodes being manufactured by the method according to any one of claims 1 to 10.

13. An accumulator comprising the electrode stack according to claim 12.

14. A traction battery, said traction battery comprising at least one accumulator according to claim 13.

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