Method for producing a battery cell

Abstract

The invention relates to a method for producing a battery cell (1), in particular for a battery for an electric vehicle. In order to produce the battery cell (1), an electrode coil (2) having an anode and a cathode is provided, wherein the anode has a carrier film with an anode coating (8) and the cathode has a carrier film with a cathode coating (7). A cylindrical cell housing (5) is also provided, wherein the cell housing (5) has an end-face opening and a circumferential bead (6) in an edge region of the opening, said bead extending radially inwards. The electrode coil (2) is arranged in the cell housing (5), and the cell housing (5) is closed. After closing, a height of the cell housing (5) is adjusted, wherein for this purpose the cell housing (5) is compressed in the axial direction to a specified height, wherein the bead (6) is deformed such that the bead presses on the electrode coil (2) in the cell housing (5), wherein the anode coating (8) is compressed at least in some regions.

Description

[0001] METHOD FOR PRODUCING A BATTERY CELL

[0002] The present invention relates to the field of batteries for electric vehicles. In particular, the invention relates to a method for manufacturing a battery cell, a battery cell manufactured in this way, a battery with several such battery cells, and a vehicle with at least one such battery.

[0003] A key focus in the development of electric or hybrid vehicles, especially those at least partially powered by electric motors, is the battery that powers the electric motor (hence also called "drive battery" or "traction battery"). Various battery cells have been developed for this purpose, such as lithium-ion cells. Several battery cells are typically arranged as a "battery pack" and, through appropriate interconnection, form a battery or battery module. It should be understood that the term "battery" in the following refers specifically to a rechargeable battery ("accumulator" or "rechargeable battery").

[0004] Battery cells can have a rigid casing in various shapes. Common types include prismatic cells (cuboidal) and cylindrical cells. In classic cylindrical cells, the layers of individual electrodes, including a separator, are wound spirally around a core within a cylindrical metal casing, forming an electrode coil in the sequence separator-anode-separator-cathode. In lithium-ion batteries, lithium ions migrate through the separator from the cathode to the anode, creating a current flowing from the negative to the positive terminal. During charging, electrons migrate from the cathode to the anode, and lithium ions migrate from the anode to the cathode.

[0005] The electrodes are typically manufactured as coated foils, with, for example, an aluminum foil coated for the cathode and a copper foil for the anode. To achieve higher energy densities in the battery cell, one option is to increase the cathode coating width. Increasing the coating width is one of the simplest ways to linearly increase energy density. However, increasing the cathode coating width is not always straightforward because the space inside the cylindrical cell casing is limited. This space is restricted not only by the outer shell but also by structures within or on the cell casing. In particular, a circumferential groove is usually provided near the end cap to mount the end cap onto the cylindrical sleeve of the cell casing.Enlarging the cell casing, particularly its height, to accommodate electrode windings with a wider coating is not a solution, as the battery cells should not have their external dimensions altered for later use, especially for integration into a battery module. Specifically, shifting the bead to create more internal space would increase the height of the battery cell. However, if the bead is not shifted, there is a risk that this inward-facing edge will press against the electrode winding, potentially causing a short circuit by damaging the wider cathode coating.

[0006] It is an object of the present invention to provide a method for manufacturing a battery cell in order to produce a battery cell with increased energy density.

[0007] The solution to this problem is achieved according to the teaching of the independent claims. Various embodiments and further developments of the invention are the subject of the dependent claims.

[0008] A first aspect of the invention relates to a method for manufacturing a battery cell. An electrode winding with an anode and a cathode is provided, the anode comprising a carrier film with an anode coating and the cathode a carrier film with a cathode coating. A cylindrical cell housing is also provided, the cell housing having an opening at one end and a circumferential groove extending radially inwards at the edge of the opening. The electrode winding is arranged in the cell housing, and the cell housing is closed. After closing, the height of the cell housing is adjusted by compressing it axially to a predetermined height, whereby the groove deforms in such a way that it presses against the electrode winding in the cell housing, thereby compressing the anode coating at least in certain areas.

[0009] The invention is therefore based, in particular, on the fact that when adjusting the height of the cell casing by compressing it, it is intentionally accepted that the bead will penetrate the anode coating or compress layers of the anode with the anode coating. This contradicts previous approaches in which such compression of the anode coating was avoided. However, it has been shown that no short circuit or safety risk occurs nonetheless. On the contrary, this finding now allows the bead to be shifted axially within the battery cell, so that an increased cathode coating width can be accommodated. This effectively increases the energy density. By compressing the bead when adjusting the height, a battery cell can still be manufactured that has predetermined dimensions or does not exceed them.

[0010] The term "electrode winding," as used here, refers in particular to a device that, as a component of a galvanic cell, especially a battery cell, serves both to store chemical energy and to deliver electrical energy. For this purpose, the electrode winding comprises at least two electrodes, namely an anode and a cathode, and a separator, in particular an electrically insulating separator, which can at least partially absorb an electrolyte, preferably containing lithium ions. The anode, separator, and cathode are wound around an axis to form an electrode winding. Before electrical energy is delivered, stored chemical energy is converted into electrical energy. During a charging process of the battery cell, electrical energy supplied to the electrode winding is converted into chemical energy and stored.It is understood that the electrode winding is particularly suitable for a cylindrical cell with a cylindrical cell casing, the height or length of which is defined in the axial direction of the cylindrical casing. The cell casing can support or form the positive and negative terminals of the battery cell.

[0011] The electrodes can (especially as a substrate foil) consist of, in particular, aluminum (Al) for the cathode and copper (Cu) for the anode, with a thin layer of a mixture of an active material, binder (e.g., PVDF, PTFE, CMC, SBR, LiPAA, PAA, etc.), and conductive additives (carbon black, CNTs, carbon fibers, etc.) applied, the so-called cathode coating or anode coating. Generally, the coating material can be an electrochemically active material (hence also referred to as an "active material") suitable for coating electrodes for battery cell windings, into which ions, especially lithium ions, can be incorporated. In addition to the materials mentioned above, the active material for the cathode can be, in particular, NMC, NCA, NCMA, LCO, LFP, LMFP, LMO, LNMO, or another material.The active material for the anode can, in particular, be graphite, SiOx, SiC, Si or another material.

[0012] The term "vehicle" as used here refers specifically to a passenger car, including all types of motor vehicles, hybrid and battery-powered electric vehicles, as well as vehicles such as sedans, vans, buses, trucks, delivery vans, and the like. The term "electric vehicle" then refers specifically to electric or hybrid vehicles, particularly vehicles that are at least partially powered by an electric motor. An electric vehicle can be, in particular, a passenger car, but also a vehicle such as a van, bus, truck, delivery van, and the like, or a two-wheeler, such as an (electric) motorcycle, (electric) scooter, e-bike, e-scooter, and the like.

[0013] The terms “comprises”, “includes”, “includes”, “indicates” may be used here 1The terms "has," "with," or any other variant thereof are intended to cover non-exclusive inclusion. For example, a method or apparatus that includes or comprises a list of elements is not necessarily limited to those elements but may include other elements not expressly listed or inherent in such a method or apparatus.

[0014] Furthermore, unless explicitly stated otherwise, "or" refers to an inclusive or and not an exclusive "or". For example, a condition A or B is satisfied by one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

[0015] The terms "ein" or "eine," as used here, are defined as "one or more." The terms "ein anderer" and "ein Weitere," as well as any other variant thereof, are to be understood as "at least one more."

[0016] The term "plural", as used here, is to be understood in the sense of "two or more".

[0017] The terms "configured" or "set up" to perform a specific function (and their respective variations) are understood within the meaning of the invention to mean that the corresponding device already exists in a configuration or setting in which it can perform the function, or at least that it is adjustable—i.e., configurable—so that it can perform the function after appropriate adjustment. Configuration can be achieved, for example, by adjusting parameters of a process sequence or by using switches or similar devices to activate or deactivate functionalities or settings. In particular, the device can have several predetermined configurations or operating modes, so that configuration can be carried out by selecting one of these configurations or operating modes.

[0018] Preferred embodiments of the method according to the first aspect are described below, which, unless expressly excluded or technically impossible, can be combined with each other as desired and with the other described aspects of the invention.

[0019] In some embodiments, the anode coating is wider than the cathode coating and extends axially beyond the cathode coating at one end of the electrode winding. This ensures that when the bead is deformed, only the anode coating is compressed, while the cathode coating remains undeformed. This guarantees the safe and reliable operation of the battery cell, while simultaneously increasing the energy density by optimally utilizing the space within the housing. In some embodiments, providing the electrode winding includes manufacturing the cathode by applying the cathode coating to the carrier film. The cathode coating has a width of more than 82 mm, preferably 84 mm.

[0020] In some embodiments, providing the electrode winding includes manufacturing the anode, wherein the anode coating is applied to the carrier foil, the anode coating having a width of more than 85 mm, preferably 87 mm.

[0021] In some embodiments, when adjusting the height of the cell housing, the cell housing is compressed in the axial direction up to a height of 95 mm.

[0022] It is understood that this dimension for the cell casing, as well as the aforementioned dimensions for the cathode coating width and anode coating width, represent only one embodiment, and other battery cell sizes, and thus other anode and cathode dimensions, are possible. However, it is clear that by increasing the cathode coating width, for example, from 82 mm to 84 mm, a widening of approximately 2%, and thus also an increase in energy density of approximately 2%, can be achieved without changing the external dimensions of the battery cell.

[0023] In some embodiments, providing the electrode winding involves compressing it axially, thereby compressing the axially projecting current conductors of the anode and cathode. These current conductors establish electrical contact with the battery cell terminals. By compressing, particularly by pinching or alternatively by folding, a contact surface for the terminals is created. Especially when the current conductors are pinched, the height of the electrode winding can also be adjusted.

[0024] In some embodiments, the cell casing is closed by an end cap, which is applied to the cell casing in the area of ​​the groove, for example by crimping. The end cap can, for example, form the positive terminal of the battery cell, with the cell casing then forming the negative terminal of the battery cell.

[0025] A second aspect of the invention relates to a battery cell produced according to a method according to the first aspect.

[0026] A third aspect of the invention relates to a battery for an electric vehicle, in particular a traction battery, which comprises several of the battery cells according to the second aspect of the invention.

[0027] A fourth aspect of the invention relates to an electric vehicle which includes at least one battery according to the third aspect of the invention as a drive battery for an electric motor of the electric vehicle.

[0028] The features and advantages explained in relation to the first aspect of the invention also apply accordingly to the other aspects of the invention.

[0029] Further advantages, features and possible applications of the present invention will become apparent from the following detailed description in conjunction with the drawings.

[0030] This shows:

[0031] Fig. 1 shows a side view of a battery cell;

[0032] Fig. 2 shows an electrode coil and a cell housing;

[0033] Fig. 3 shows a section through a battery cell;

[0034] Fig. 4 schematically shows a section of a sectional view of a battery cell in the area of ​​the groove; and

[0035] Fig. 5 shows a section through one end of a battery cell.

[0036] Figure 1 shows a side view of a cylindrical battery cell 1. The cylindrical cell housing 5 is closed at one end with an end cap 10 (here, a plate- or disc-shaped cap). A groove 6 runs around this area, serving both to mount the end cap 10 and to allow adjustment of the height of the battery cell 1, i.e., its axial dimension, as explained in more detail below. The inward curvature of the groove 6 allows the cell housing 5 to deform when a pressure force is applied to it in the axial direction after it has been closed, using a corresponding module during manufacturing. An electrode winding 2 is housed within the cell housing 5, comprising a winding of anode layers, cathode layers, and separator layers.

[0037] Figure 2 illustrates an electrode winding 2. A carrier film 3 with a coating 4 is visible, for example, the cathode with a cathode coating or the anode with an anode coating. The free edge forms current collectors, which, during the manufacture of the electrode winding 2, can form a contact surface for the terminals of the battery cell, for example, by compression in the axial direction (not shown in detail).

[0038] Fig. 3 shows a section (or X-ray section) through battery cell 1. In the upper area, the groove 6 and the mounted end cap 10, which closes the cell housing 5, are visible. Also visible are the areas of the cathode coating 7 and the anode coating 8, which projects axially beyond the cathode coating 7. The width 11 of the cathode coating (which also corresponds to the "height" in battery cell 1) is approximately 84 mm in this example, which is about 2 mm greater than that of conventional battery cells with the same external dimensions. The width 12 of the anode coating is approximately 87 mm in this example. The overall height or length of battery cell 1 is 95 mm. The increased coating widths 11 and 12 cause the groove 6 to extend into the area of ​​the anode coating 8, as described below.

[0039] The increased cathode coating width 11 is accommodated in the battery cell 1 primarily by shifting the corrugation 6 upwards compared to conventional battery cell designs with the same external dimensions. While this initially increases the cell height after sealing and makes the cell longer, the desired cell height is then achieved by pressing the cell downwards after sealing. This is indicated in Fig. 4 by the downward-pointing white arrow. The space gain is mainly achieved by compressing the corrugation 6, which also deforms in the direction of the black arrows indicated in Fig. 4.

[0040] The idea is that the penetration of the bead 6 into the anode coating 8 is intentionally accepted, at least in the area designated and circled by 9 in Fig. 5, in order to accommodate the greater width 11 of the cathode coating 7, since no short circuit and no safety risk is to be expected from the penetration of the bead 6 into the anode coating 8.

[0041] While at least one exemplary embodiment has been described above, it should be noted that a large number of variations exist. It should also be noted that the described exemplary embodiments are merely non-limiting examples, and it is not intended to restrict the scope, applicability, or configuration of the devices and methods described herein. Rather, the preceding description will provide the person skilled in the art with guidance for implementing at least one exemplary embodiment. It is understood that various modifications to the function and arrangement of the elements described in an exemplary embodiment can be made without derogating from the subject matter defined in the appended claims and their legal equivalents.

[0042] REFERENCE MARK LIST

[0043] 1 battery cell

[0044] 2 electrode coils

[0045] 3 T carrier film 4 coating

[0046] 5 cell casings

[0047] 6 groove

[0048] 7 Cathode coating

[0049] 8 Anode coating 9 Compressed area of ​​the anode coating

[0050] 11 Height / width of the cathode coating

[0051] 12 Height / width of the anode coating

Claims

REQUIREMENTS 1. Method for manufacturing a battery cell (1), comprising the following steps: Providing an electrode winding (2) with an anode and a cathode, wherein the anode has a carrier foil with an anode coating (8) and the cathode has a carrier foil with a cathode coating (7); Providing a cylindrical cell housing (5), wherein the cell housing (5) has an end face opening and has a circumferential groove (6) in an edge region of the opening which extends radially inwards; Arranging the electrode coil (2) in the cell housing (5); Closing the cell casing (5); and Adjusting the height of the cell housing (5), wherein the cell housing (5) is compressed in the axial direction up to a predetermined height, whereby the groove (6) deforms in such a way that it presses on the electrode winding (2) in the cell housing (5), whereby the anode coating (8) is compressed at least in some areas.

2. Method according to claim 1, wherein the anode coating (8) is wider than the cathode coating (7) and extends axially beyond the cathode coating (7) in an end region of the electrode winding (2), so that when the bead (6) is deformed only the anode coating (8) is compressed, but the cathode coating (7) remains free from deformation.

3. Method according to claim 1 or 2, wherein the provision of the electrode winding (2) comprises the production of the cathode, wherein the cathode coating (7) is applied to the carrier film, wherein the cathode coating (7) has a width (11) of more than 82 mm, preferably 84 mm.

4. Method according to one of the preceding claims, wherein the provision of the electrode winding (2) comprises the production of the anode, wherein the anode coating (8) is applied to the carrier foil, wherein the anode coating (8) has a width (12) of more than 85 mm, preferably 87 mm.

5. Method according to one of the preceding claims, wherein when adjusting the height of the cell housing (5) the cell housing (5) is compressed in the axial direction up to a height of 95 mm.

6. Method according to one of the preceding claims, wherein the provision of the electrode winding (2) comprises compressing the electrode winding (2) in an axial direction, thereby compressing current conductors of the anode and the cathode projecting in an axial direction.

7. Method according to one of the preceding claims, wherein the cell housing (5) is closed by an end cap (10) which is applied to the cell housing (5) in the area of ​​the groove (6).

8. Battery cell (1) manufactured according to a method according to one of the preceding claims.

9. Battery with multiple battery cells (1) according to claim 8.

10. Electric vehicle with at least one battery according to claim 9 as a drive battery for an electric motor of the electric vehicle.

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