Battery cell

Abstract

A battery cell (100) has a cylindrical housing (110) and an electrode winding (120) having a layered structure (200) wound around a winding core (190). At least one electrode has a current collector (150) protruding in the longitudinal direction, wherein the electrode winding (120) is arranged in the housing (110) in such a way that an electrical contact to a positive terminal or negative terminal of the battery cell (100) is formed by the current collector (150). The current collector (150) has a plurality of tabs (151, 152) which extend in the longitudinal direction from corresponding tabs of the anode layer and the cathode layer, wherein the tabs (151, 152) are bent over in order to thus form a contact plane on a corresponding end face of the electrode winding (120) for the electrical contact. The tabs (151, 152) are bent in a direction toward the winding core (190) in a first region, which circumferentially adjoins an outer circumference of the electrode winding (120), and in a direction away from the winding core (190) in a second region of the end face, which circumferentially adjoins the winding core (190).

Description

[0001] 23-2238

[0002] BATTERY CELL

[0003] The present invention relates to the field of batteries for electric vehicles. In particular, the invention relates to a battery cell, a battery with several such battery cells, and a vehicle with at least one such battery.

[0004] 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").

[0005] Battery cells can have a rigid casing in various shapes. Common types include prismatic cells (cuboidal) and cylindrical cells. Each cell comprises several layers: an electrode called the "anode" (negative terminal), an electrode called the "cathode" (positive terminal), and a separator located between the two electrodes to electrically separate them (i.e., to prevent electrons from passing through) and to conduct ions. In cylindrical cells, the layers of the individual materials—the electrodes including the separator—are wound in a spiral around a core within a cylindrical metal casing, forming an electrode coil. In the case of lithium-ion batteries, lithium ions migrate through the separator from the cathode to the anode, creating a current flowing from the negative terminal to the positive terminal.During charging, electrons migrate from the cathode to the anode, and lithium ions migrate from the anode to the cathode.

[0006] Cylindrical battery cells are known in which the electrode ends of like-polarized electrodes, in particular cathodes, which are electrically positive, are electrically connected to a so-called terminal terminal. The terminal terminal can be formed on a base plate of the cell housing, wherein the terminal terminal is electrically insulated from the cell housing. An electrically positive pole of the battery cell can be contacted from outside the battery cell via the terminal terminal. Similarly, the electrode ends of anodes, which are electrically negative, can be electrically connected to the cell housing, which is also electrically conductive, so that the electrically negative pole of the battery cell can be contacted via the cell housing. Alternatively, the terminal terminals can also be provided on the opposite end faces of the battery cell.

[0007] The contact between the electrodes and the respective terminal of the battery cell (e.g., terminal connection or cell casing as explained above) can be established, for example, by having the layer forming the corresponding electrode protrude from the layer structure at one side edge, thus projecting as a current collector at one end of the electrode winding. A lateral edge of the cathode protrudes from the electrode winding at one end, and a lateral edge of the anode at the other. This spiral current collector, created by the winding process, is then compacted on the respective end face of the electrode winding to improve electrical contact, thereby establishing essentially planar contact between the electrodes and the respective terminals. In particular, contact with the positive terminal can be established by a welded connection to a terminal disc on the end face of the electrode winding.

[0008] Therefore, notches or recesses can be provided in the protruding edges so that the current collectors are formed by a multitude of protruding tabs. These tabs can then be folded or bent over to create a more uniformly compacted and gas-permeable layer. To prevent the tabs of the outer winding layers from contacting the cell casing, they are usually folded over towards the winding core. However, since the winding core would then be closed off by the folded tabs of the inner winding layers, and the tabs would obstruct each other in the core area, it is known to omit current collectors (or tabs) in this area.

[0009] However, due to the lack of a current collector in the core area of ​​the electrode winding, inhomogeneities can occur during charging and discharging. Furthermore, this places greater stress on the electrode material, for example, through increased heating or lithium plating in this area. This can result in a shorter battery cell lifespan, especially during rapid charging and discharging (i.e., at high C-rates). This is primarily due to the reduced weld area between the (positive) current collector and the (positive) terminal disk caused by the missing tabs in the core area of ​​the electrode winding.

[0010] It is an object of the present invention to provide a battery cell, in particular a cylindrical battery cell, with an improved design compared to the prior art. In particular, this is intended to provide a battery cell with improved current collectors on the end faces of the electrode winding.

[0011] 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.

[0012] A first aspect of the invention relates to a battery cell comprising a cylindrical housing and an electrode winding with a layered structure wound around a core, wherein the layered structure includes an anode layer, a cathode layer, and at least one separator layer for electrical separation of the anode and cathode layers. At least one of the anode and cathode layers has a longitudinally projecting current collector, wherein the electrode winding is arranged in the housing such that the current collector forms an electrical contact with a positive or negative terminal of the battery cell. The current collector has a plurality of tabs extending longitudinally from corresponding anode and cathode layers, the tabs being bent over to form a contact plane on a corresponding end face of the electrode winding for electrical contact.In a first area, which borders the outer circumference of the electrode winding, the tabs are bent in one direction towards the winding core, whereas in a second area of ​​the end face, which borders the winding core, they are bent in one direction away from the winding core. 23-2238.

[0013] The invention is therefore based on the fact that the tabs of the current collector are bent (folded) in different directions. In an outer area, the tabs are bent inwards, i.e., towards the winding core, so that they do not protrude beyond the circumference of the electrode winding. In contrast, the tabs in an inner area are bent outwards, i.e., away from the winding core, so that they do not protrude into the winding core. The winding core should, in particular, remain unobstructed to avoid impeding the flow of the electrolyte. Due to the change in direction during the bending, the tabs can also be provided in the inner area instead of leaving this area unobstructed.

[0014] This allows, in particular, the welding surface of a terminal plate to be enlarged. Specifically, this enables the current collector to have a substantially constant transverse extent along the length of the layer structure, thus ensuring a homogeneous current flow during charging and discharging, especially during rapid charging and discharging processes. Heat generation can also be reduced. This can result in an overall extended lifespan for the battery cell. Furthermore, lithium plating can be prevented or reduced.

[0015] 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.

[0016] The term "current collector," as used here, refers specifically to an element made of a conductive material, particularly copper or aluminum. It serves to conduct electricity between two geometrically separated points. 23-2238

[0017] 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. 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.The electrodes can have a current collector, in particular made of aluminum (Al) for the cathode and copper (Cu) for the anode, wherein 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.) can be applied to both sides of the current collector. The current collector can in particular be designed as a foil.

[0018] The term "separator" or "separator layer," as used here, refers in particular to an electrically insulating device that separates and distances an anode from a cathode. Preferably, a separator layer is applied to an anode layer and / or a cathode layer. Preferably, the separator layer is designed as an independent body. The separator or separator layer can also at least partially contain an electrolyte, which preferably contains lithium ions. The electrolyte can also be electrochemically bonded to adjacent layers of an electrode stack or electrode winding. Preferably, a separator is thin-walled, particularly preferably as a microporous film. Preferably, the separator layer or separator is wetted with an additive that also increases the mobility of the separator layer or separator.Wetting with an ionic additive is particularly preferred. Preferably, the separator layer or the separator extends at least partially over a boundary edge of at least one electrode. In the layer structure, at least one separator layer is arranged between the cathode layer and the anode layer, and usually another at 23-2238.

[0019] The separator layer, or the anode layer, ensures electrical separation of the electrode layers in the electrode winding. It is understood that the separator layer, as well as the cathode and anode layers, can have a substantially rectangular shape, resulting in a cylindrical shape when rolled up. The longitudinal ends are referred to here as the ends in the longitudinal direction.

[0020] The term "active material," as used here, refers in particular to a material that can be electrochemically active and is suitable for coating electrodes for battery cell windings, and into which ions, especially lithium ions, can be incorporated. The active material for the cathode may, in particular, be NMC, NCA, NCMA, LCO, LFP, LMFP, LMO, LNMO, or another material. The active material for the anode may, in particular, be graphite, SiOx, SiC, Si, or another material.

[0021] 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.

[0022] 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).

[0023] The terms “a” or “an,” as used here, are defined as “one or more.” The terms “another” and “another,” as well as any other variant thereof, are to be understood as “at least one more.” 23-2238

[0024] The term "plural", as used here, means "two or more". 1 to understand.

[0025] 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.

[0026] Preferred embodiments of the battery cell 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.

[0027] In some embodiments, the first area is wider than the second area with respect to the radius of the end face. In other words, over most of the surface, the current collector tabs are bent inwards, i.e., towards the winding core. Only in an inner area around the winding core are the tabs bent in the other direction, i.e., outwards, away from the winding core.

[0028] In some embodiments, the first and second regions are spaced apart radially by a distance at least equal to the length of a bent portion of a tab. This prevents the tabs from interfering with each other during bending. In particular, this prevents the formation of a contact plane area where the inwardly bent tabs collide with the outwardly bent tabs in such a way as to cause an accumulation. The contact plane can thus be designed to be essentially flat, enabling a clean weld connection 23-2238, for example, to a terminal disc, which is advantageous for homogeneous charging behavior.

[0029] In some embodiments, the first and second regions are spaced apart radially by a distance of at most twice the length of a bent portion of a tab. In particular, this distance should be such that the inwardly bent and outwardly bent tabs can still bridge the gap without creating a gap in the contact plane. This allows, for example, a welded connection to a terminal plate to be made without interruption, which is also advantageous for homogeneous charging behavior.

[0030] In some embodiments, the electrode winding is connected to the positive terminal by means of a connecting disc arranged on its end face. This (positive) connecting disc establishes electrical contact between the electrode winding (or more precisely, the anode) via the contact plane formed by the bent tabs and a terminal of the battery cell, which forms the positive terminal of the battery cell. It can, in particular, extend over the entire surface of the end face of the electrode winding.

[0031] In some related embodiments, the connecting disc is welded to the electrode winding in at least one connection area. The measures described above allow for the formation of the largest possible weld connection, particularly in a central area around the winding core.

[0032] In some embodiments, both the anode layer and the cathode layer have a corresponding current collector, with the current collector of the anode layer and the current collector of the cathode layer being located on opposite end faces of the electrode winding. This simple spatial separation of the anode and cathode current collectors allows for electrical contact to be established with the respective terminals of the battery cell.

[0033] A second aspect of the invention relates to a method for manufacturing a battery cell, in particular a battery cell according to the first aspect of the invention. For this purpose, a cylindrical housing and an electrode winding with a layered structure wound around a core are provided, wherein the layered structure comprises an anode layer, a cathode layer, and at least one separator layer for electrical separation of the anode layer and the cathode layer, wherein at least one of the anode layer and the cathode layer has a longitudinally projecting current collector, the current collector having a plurality of tabs which extend longitudinally from corresponding parts of the anode layer and the cathode layer. The tabs are bent over to form a contact plane on a corresponding end face of the electrode winding for electrical contact with a positive terminal.The negative terminal of the battery cell is formed by bending the tabs in a first area, which borders the outer circumference of the electrode winding, in a direction towards the winding core, and in a second area of ​​the end face, which borders the winding core, in a direction away from the winding core. The electrode winding is arranged in the housing, with the electrical contact to the positive or negative terminal of the battery cell being formed by the current collector.

[0034] A third aspect of the invention relates to a battery for an electric vehicle, in particular a traction battery, which comprises at least one battery cell according to the first aspect of the invention and / or at least one battery cell produced according to the method according to the second aspect of the invention.

[0035] 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.

[0036] The features and advantages explained in relation to the first aspect of the invention also apply accordingly to the other aspects of the invention.

[0037] Further advantages, features and possible applications of the present invention will become apparent from the following detailed description in conjunction with the drawings.

[0038] This shows: 23-2238

[0039] Fig. 1 shows a section through a cylindrical battery cell;

[0040] Fig. 2 shows a layer structure for an electrode winding in top view;

[0041] Fig. 3 shows an electrode coil before the tabs are bent over; and

[0042] Fig. 4 shows an electrode coil after bending the tabs.

[0043] The same reference numerals are used throughout the figures for the same or corresponding elements of the invention.

[0044] Fig. 1 shows a schematic cross-sectional view of a cylindrical battery cell 100 (round cell), particularly for use in an electric vehicle battery. It could, for example, be a lithium-ion cell. Typically, several battery cells 100 are combined to form a battery pack, which constitutes a battery for an electric vehicle (not shown), in particular a traction battery for the electric motor of the electric vehicle. The battery cell 100 can, for example, have a diameter of 46 mm and a length of 95 mm.

[0045] The battery cell 100 has a housing 110 in the form of a hollow cylinder made of an electrically conductive material. An electrode winding 120 is arranged in the housing 110, which can be formed by winding a corresponding layered structure (see Fig. 2) around a core 190. An anode of the electrode winding 120 is connected to a base plate 130 of the housing 110 via a current collector 150 and corresponding electrical connections 140. The base plate 130, like the anode current collector 150, can be made of copper, and the battery cell 100 can be electrically connected to it from outside the housing 110 via the base plate 130.

[0046] Similarly, a contact plate 170 is arranged on a side of the hollow cylinder 110 opposite the base plate 130. This contact plate has an electrically conductive material and is electrically connected to the cathode via electrical connections 180 to a cathode current collector 160, so that the battery cell 100 can be electrically connected from outside the battery cell 100 23-2238 via the contact plate 170. The contact plate 170 and the electrical connections 180 are made of aluminum. The cathode current collector 160, as well as the previously mentioned anode current collector 150, can each be formed by bending corresponding tabs, as will be explained in more detail below.

[0047] Figure 2 shows a schematic, not to scale, top view of a layer structure 200, which, when wound, forms an electrode winding. The layer structure 200 comprises an anode layer, a cathode layer, and a separator layer, which electrically separates the anode and cathode layers (layers not shown individually).

[0048] The layered structure 200 has a substantially rectangular basic shape and can be wound, i.e., coiled, from a first longitudinal end 201 to a second longitudinal end 202 (indicated by the arrow). The first longitudinal end 201 is then located at the winding core 190. The current collectors 150 project from the anode so that the electrical connections described in connection with Fig. 1 can be established.

[0049] In Fig. 2 (as well as Fig. 3 and Fig. 4), only the current collectors 150 of the anode for the positive terminal are illustrated. It is understood that this can be provided equally for the current collectors 160 of the cathode for the negative terminal.

[0050] The current collector 150 has a plurality of tabs 151, 152, which are interrupted by a section 153 in which no tabs are provided. It is understood that the number and exact arrangement of the tabs are merely schematic and serve to illustrate the principle of the invention.

[0051] Fig. 3 shows the layer structure in its wound state. The tabs 151 are located in a region of the end face of the electrode winding 120 formed by winding the layer structure 200, which borders a circumferential outer circumference of the electrode winding 120. The tabs 152 are located in a region of the end face of the electrode winding 120 that borders the winding core 190. Due to the region 153 without tabs, the wound 23-2238

[0052] The distance between the two areas with the tabs 151 and the tabs 152 is 154.

[0053] Fig. 4 schematically shows the electrode winding 120 after the tabs 151, 152 have been bent over. While here only a part 15T, 152' of the tabs 151, 152 has been bent over, it is understood that the tabs 151, 152 can also be bent over substantially completely. Furthermore, the bending can be carried out in such a way that the bent parts 15T, 152' (or the entire tabs 151, 152) lie flatter than shown after bending, in particular, substantially completely flat.

[0054] The tabs 151 were bent in one direction towards the winding core 190. Thus, after bending, these outer tabs 151 do not protrude outwards beyond the edge of the electrode winding 120. The inner tabs 152, on the other hand, were bent in one direction away from the winding core 190 so that they do not protrude into the winding core 190 after bending. The spacing 154 ensures that the tabs 151, 152 do not obstruct each other when bent, and also prevents a gap from forming in the contact plane. The spacing 154 is greater than or equal to the length of the bent portion 15T, 152' of the tabs 151, 152, but less than or equal to twice the length of the bent portion 15T, 152' of the tabs 151, 152.

[0055] 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 only 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 changes can be made to the function and arrangement of the elements described in an exemplary embodiment without derogating from the subject matter defined in the appended claims and their legal equivalents. 23-2238

[0056] REFERENCE MARK LIST

[0057] 100 battery cells

[0058] 110 cases

[0059] 120 electrode coils

[0060] 130 Base plate

[0061] 140 electrical connections

[0062] 150 current collector anode

[0063] 151 tabs

[0064] 15T bent part of the tabs

[0065] 152 tabs

[0066] 152' bent part of the tabs

[0067] 153 Area without tabs

[0068] 154 distance

[0069] 160 current collector cathode

[0070] 170 contact plate

[0071] 180 electrical connections

[0072] 190 winding core

[0073] 200 layer structure

[0074] 201 first longitudinal end

[0075] 202 second longitudinal end

Claims

1. 23-2238 REQUIREMENTS 1. Battery cell (100) comprising a cylindrical housing (110) and an electrode winding (120) with a layer structure (200) wound around a winding core (190), wherein the layer structure (200) comprises an anode layer, a cathode layer and at least one separator layer for electrical separation of the anode layer and the cathode layer, wherein at least one of the anode layer and the cathode layer has a longitudinally projecting current collector (150), wherein the electrode winding (120) is arranged in the housing (110) such that the current collector (150) provides electrical contact to a positive terminal.The negative terminal of the battery cell (100) is formed, wherein the current collector (150) has a plurality of tabs (151, 152) which extend in the longitudinal direction from the anode layer and the cathode layer, wherein the tabs (151, 152) are bent over to form a contact plane on a corresponding end face of the electrode winding (120) for electrical contact, wherein the tabs (151, 152) are bent over in a first area which is circumferentially adjacent to an outer circumference of the electrode winding (120) in a direction towards the winding core (190) and in a second area of ​​the end face which is circumferentially adjacent to the winding core (190) in a direction away from the winding core (190).

2. Battery cell according to claim 1, wherein the first area is wider than the second area with respect to a radius of the end face.

3. Battery cell according to claim 1 or 2, wherein the first region and the second region have a distance (154) from each other in the radial direction which corresponds to at least one length of a bent part (15T, 152') of a tab (151 , 152).

4. Battery cell according to one of the preceding claims, wherein the first region and the second region are spaced apart in the radial direction (154) 23-2238 to each other, which corresponds at most to twice the length of a bent part (15T, 152') of a tab (151 , 152).

5. Battery cell according to one of the preceding claims, wherein the electrode winding (120) is connected to the positive terminal by means of a connecting disk arranged at the end face of the electrode winding (120).

6. Battery cell according to claim 5, wherein the connecting disc is welded to the electrode winding (120) in at least one connection area.

7. Battery cell according to one of the preceding claims, wherein both the anode layer and the cathode layer have a corresponding current collector (150, 160), wherein the current collector (150) of the anode layer and the current collector (160) of the cathode layer are located on opposite end faces of the electrode winding.

8. Method for manufacturing a battery cell (100), in particular a battery cell (100) according to one of the preceding claims, comprising the following steps: Providing a cylindrical housing (110) and an electrode winding (120) with a layered structure (200) wound around a winding core (190), wherein the layered structure (200) comprises an anode layer, a cathode layer and at least one separator layer for electrical separation of the anode layer and the cathode layer, wherein at least one of the anode layer and the cathode layer has a longitudinally projecting current collector (150), wherein the current collector (150) has a plurality of tabs (151, 152) which extend in the longitudinal direction from corresponding parts of the anode layer and the cathode layer; Bending the tabs (151, 152) to form a contact plane on a corresponding end face of the electrode winding (120) for electrical contact with a positive or negative terminal of the battery cell (100), wherein the tabs (151, 152) in a first area, 23-2238 which is circumferentially adjacent to an outer circumference of the electrode winding (120), be bent in one direction towards the winding core (190) and in a second area of ​​the end face, which is circumferentially adjacent to the winding core (190), bent in one direction away from the winding core (190); and Arranging the electrode winding (120) in the housing (110), wherein the electrical contact to the positive terminal or negative terminal of the battery cell (100) is formed by the current conductor (150).

9. Battery comprising at least one battery cell (100) according to any one of claims 1 to 7 and / or at least one battery cell (100) produced according to the method of 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. 16 / 17

Images