Battery cell

Abstract

The invention relates to a battery cell, having a positive pole and a negative pole and a seal which is arranged in an intermediate space between the positive pole and the negative pole and electrically insulates them from one another. A support device, the height of which is smaller than a distance between the positive pole and the negative pole, is arranged in the intermediate space in a region without the seal. The support device is dimensioned and configured in such a way that, in the event of a fault in which the positive pole and the negative pole approach one another as a result of damage to the seal, the positive pole and the negative pole rest on top of one another, such that an electrically conductive contact is established between the positive pole and the negative pole by means of the support device.

Description

[0001] 24-2218

[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, an energy storage device with at least one such battery cell, and an electric vehicle with at least one such energy storage device as a traction 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 (series or parallel) connection, form a battery or battery module (also referred to as a "high-voltage storage device" or, more generally, an "energy storage unit"). It should be understood that the term "battery" (or battery cell) in the following refers specifically to a rechargeable battery ("accumulator" or "rechargeable battery").

[0005] Battery cells can have a rigid casing in various shapes. Well-known types are 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 cell casing to form an electrode coil. The cell casing can form the negative terminal (anode) of the battery cell, while the positive terminal (cathode) can be formed by a terminal connection on one end of the cell casing. The negative and positive terminals are electrically insulated from each other by, for example, a ring-shaped (plastic) insulation, which can also act as a seal.

[0006] In the event of a fault, particularly a thermal event in a battery cell, the seal can melt or degrade. Specifically, it can lose height, causing the positive and negative terminals to approach each other and make contact, which can create a medium-resistance short circuit, leading to a sustained [24-2218]

[0007] A low current flow can occur through this damaged cell from the neighboring cells. A medium-resistance short circuit can arise particularly because the contact surfaces between the positive and negative terminals remain separated by remnants of the seal, which allow a low current flow. Specifically, this prevents direct contact, or in other words, a "hard," i.e., low-resistance, short circuit.

[0008] The individual battery cells in high-voltage storage systems are contacted and interconnected via cell connectors (for example, made of aluminum). These connectors typically have a fuse at each contacted cell to disconnect in case of overload. These fuses trigger at varying current levels and within different timeframes, protecting the storage system from overload and cell damage. However, the low current flow described above is typically insufficient to trigger a fuse and can therefore flow for a relatively long time. Due to the continuous heat generation, the surrounding cells can also heat up, potentially causing thermal propagation. The cell connectors themselves can also heat up, damaging plastic insulation and allowing the connectors to make contact with and damage the surrounding cells.

[0009] It is therefore an object of the present invention to improve the safety characteristics of an energy storage device, in particular with regard to the described problem of thermal propagation.

[0010] 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.

[0011] A first aspect of the invention relates to a battery cell comprising a positive terminal and a negative terminal, as well as a seal which is arranged in a space between the positive and negative terminals and electrically insulates them from each other. In the space, in an area without the seal, a support device is arranged, the height of which is less than the distance between the positive and negative terminals. The support device is dimensioned and configured such that, in the event of a fault where damage to the seal causes the positive and negative terminals to come into contact,

[0012] The two parts come into contact with each other, so that an electrically conductive contact is established between the positive and negative poles by means of the support device.

[0013] The term "fault condition" used here refers specifically to a case or situation in which the battery cell does not function properly, i.e., it malfunctions. A fault condition can have various causes, such as aging, an internal short circuit, a thermal event, etc. In the case of overheating, the electrically insulating seal between the positive and negative terminals can at least partially melt or degrade. This can cause the seal to lose height (thickness), potentially leading to the positive and negative terminals coming into close proximity. Conversely, "normal operation" refers to the "regular operation" in which the battery cell or its components function, are designed, or arranged "normally" or "as intended."

[0014] 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.

[0015] 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 method or apparatus.

[0016] Furthermore, unless expressly 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 conditions: A is true (or24-2218)

[0017] A is 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).

[0018] 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."

[0019] The term "plural", as used here, is to be understood in the sense of "two or more".

[0020] 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.

[0021] The invention is therefore based on increasing the safety properties of an energy storage device by making adjustments within the battery cell(s). In particular, by means of the mounting device in a battery cell, a complete short circuit can be deliberately induced in the event of a fault in the space between the positive and negative terminals, thus preventing propagation.

[0022] This can be deliberately achieved by providing the support device. Under normal operating conditions, due to the height of the support device, which is less than the distance between the positive and negative terminals, there is no electrically conductive contact between the two terminals. In other words, the support device is thinner than the seal, so electrical insulation is not provided by the seal. 24-2218

[0023] This is to be ensured. However, if the seal loses height in the event of a fault, an electrical contact between the two poles is created by the support device. The support device is located in an area of ​​the gap without a seal, meaning that in the event of a fault, the support device is not contaminated by seal remnants, allowing direct contact, especially metal-to-metal contact, between the positive and negative terminals. This can cause a high current to flow briefly in the defective battery cell, which in turn can trigger a (melt) fuse at a connector to an adjacent cell. The defective cell is thus disconnected from the system. This prevents, in particular, a low current flowing through the defective cell over a longer period, which can gradually lead to overheating of the neighboring cells. Any associated propagation can thus be avoided.

[0024] 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.

[0025] In some embodiments, the battery cell has a housing (also called a "cell housing" or "cell can") and a terminal connection, wherein the negative terminal or the positive terminal is at least partially formed by the housing, and wherein the other terminal of the negative and positive terminals is formed by the terminal connection. In particular, it may be provided that the housing (at least partially) forms the negative terminal and the terminal connection the positive terminal. The housing may, in particular, be a cylindrical housing, so that the battery cell is a round cell. The terminal connection may, in particular, be a connection on an end face of the housing. The seal may then, in particular, be disc-shaped or ring-shaped.

[0026] In some embodiments, the support element is at least partially arranged in a recess of the seal. The recess is then to be understood as part of the "area without the seal". For example, the support element (e.g., in the form of one or more projections, su) can extend through an opening in 24-2218

[0027] The wires extend through the seal. This allows for a simple way to establish direct electrical contact between the positive and negative terminals in the event of a fault, without any remaining parts of the damaged seal. This can facilitate current flow and, as explained above, a short circuit.

[0028] In some embodiments, the support device has at least two spaced-apart contact areas. By distributing the force exerted when the positive and negative terminals rest on the device over the surface area of ​​these contact areas, the force on the support device is increased, which in turn (in the event of a fault) leads to improved electrical contact between the positive and negative terminals. In some related embodiments, the contact areas are uniformly distributed along the entire length of the support device, for example, around the circumference of the battery cell or the seal. This allows for better force distribution.

[0029] In some embodiments, the support device has at least one projection extending from at least one of the positive and negative terminals through the gap towards the other of the positive and negative terminals. In particular, with regard to the embodiments described above, the support areas can be formed by projections.

[0030] In some embodiments, the support device is designed such that the contact between the positive and negative poles is statically determinate. In particular, for example, three contact areas or three projections may be provided. With precisely three contact areas, the support is statically determinate even with a planar extension of the support device. This prevents overloading of a single support and ensures stable load transfer while simultaneously maximizing the force-to-area ratio.

[0031] A second aspect of the invention relates to an energy storage device, in particular a battery for an electric vehicle, in particular a traction battery, also called a high-voltage storage device, with at least one battery cell according to the first aspect of the invention and at least one connector, wherein the battery cell is connected to at least one further component of the 24-2218 by means of a connector.

[0032] The energy storage device is electrically connected. The connector includes an electrical fuse designed to interrupt the electrical connection between the battery cell and at least one other component if the current across it exceeds a predetermined fuse current for more than a specified period. The mounting device is designed such that a current defined by the mounting device's current-carrying capacity exceeds the fuse current.

[0033] In particular, the mounting device can be dimensioned (designed), especially with regard to its dimensions such as surface area and height, such that a current defined by the current-carrying capacity of the mounting device is greater than the rated current of the fuse. The material also influences the current-carrying capacity and should be advantageously matched. This ensures that the fuse trips due to the short circuit in the battery cell created by the mounting device, as explained above, and isolates the defective battery cell from its surroundings to prevent propagation.

[0034] The further component can in particular be another battery cell, especially also a battery cell according to the first aspect of the invention. Several battery cells can be connected in series and / or in parallel with each other by means of suitable connectors (hence also called cell connectors) according to a desired requirement, in particular with regard to a total voltage of the energy storage device. The electrical fuse can in particular be or comprise a fuse.

[0035] A third aspect of the invention relates to an electric vehicle which comprises at least one energy storage device according to the second aspect of the invention as a battery, in particular a traction battery for an electric motor of the electric vehicle.

[0036] The features and advantages explained with regard to the first and second aspects of the invention also apply accordingly to the other aspects of the invention.

[0037] Further advantages, features and applications of the present invention will become apparent from the following detailed description in conjunction with the drawings. 24-2218

[0038] This shows:

[0039] Fig. 1 shows a schematic sectional view of a battery cell with a connector for contacting it in an energy storage device;

[0040] Fig. 2 is a detail view from Fig. 1; and

[0041] Fig. 3 shows a top view of the battery cell from Fig. 1.

[0042] Figure 1 shows a schematic cross-sectional view of a battery cell 1. The battery cell 1 has a positive terminal 2, here in the form of a terminal connection, and a negative terminal 3, here in the form of the battery cell housing. The positive terminal 2 and the negative terminal 3 are electrically insulated from each other by means of a seal 4, here in particular in the form of a ring. The seal 4 also seals the interior of the battery cell 1 from the environment. The battery cell 1 is part of an energy storage device 5, in particular in the form of a (traction) battery for an electric vehicle. For this purpose, several of the battery cells 1 are connected to each other via connectors 6, i.e., interconnected. An electrical fuse 7, in particular a fuse in the connector 6, disconnects the battery cell 1 from the rest of the energy storage device 5 in the event of a fault, such as a thermal event, internal short circuit, or the like.

[0043] Fig. 2 is a detail view from Fig. 1 (Detail II). During a thermal event, the seal 4 melts or degrades due to the heat generated. This allows the positive terminal 2 and the negative terminal 3 to approach each other, potentially leading to contact. In known battery cells, this contact can then be ring-shaped. This uncertainty results in undesirable side effects such as low current flow over extended periods, accompanied by propagation. This occurs particularly because the low current flow is insufficient to trip the fuse 7.

[0044] A controlled adjustment of a defined contact between positive terminal 2 and negative terminal 3 in the event of a fault can be used to create a hard, low-resistance short circuit. This current flow can then be sufficient to trip fuse 7, as described in detail below. This allows a 24-2218

[0045] The defective battery cell is disconnected from the system and propagation is prevented. This contact is achieved by a support device 8, which in this embodiment is formed by three projections.

[0046] The support element 8 is located in a space between the positive terminal 2 and the negative terminal 3, in which the seal 4 is also located. To ensure electrical insulation between the positive terminal 2 and the negative terminal 3 under normal operating conditions, the support element 8 has a height that is less than the distance between the positive terminal 2 and the negative terminal 3. The support element 8, i.e., the three projections, is located in an area without the seal 4, specifically in three corresponding recesses in the seal 4. This creates a free space 9 in each recess. If the seal 4 degrades due to a fault, a defined contact occurs between the positive terminal 2 and the negative terminal 3, as they rest against each other via the support element 8.

[0047] In this embodiment, the support element 8, i.e., the projections 8, extend from the housing (negative terminal 3) towards the terminal connection (positive terminal 2). It is understood that this can also be reversed. Projections can also extend from both the positive terminal 2 and the negative terminal 3 through the gap towards the other terminal. The support element 8 can, for example, be manufactured directly during the deep drawing of the housing. Other manufacturing methods, such as attaching the support element by welding, are also possible.

[0048] Figure 3 shows a schematic top view of the battery cell 1. In particular, it illustrates that the three projections of the support device 8 are evenly distributed around the circumference of the seal 4. Furthermore, they are positioned as close as possible to the edge of the seal 4 to achieve high force transmission (see Figure 2).

[0049] The arrangement of the three protrusions ensures that the force occurring when positive pole 2 and negative pole 3 make contact is distributed evenly across the protrusions. This prevents overloading of a single protrusion and ensures stable load transmission while maintaining a maximum force-to-area ratio. Furthermore, 24-2218

[0050] The contact is statically determined by providing exactly three protrusions, which is also advantageous for a defined contact.

[0051] The cross-section and, in particular, the current-carrying capacity of the mounting device 8 are higher than those of the upstream fuse 7. In other words, the rated current of the fuse 7 is lower than the current defined by the current-carrying capacity of the mounting device 8. This ensures that, in the event of a fault, when the mounting device 8 makes electrical contact between the positive terminal 2 and the negative terminal 3, the fuse 7 will trip. 24-2218

[0052] REFERENCE MARK LIST

[0053] 1 battery cell

[0054] 2 Positive terminal / Terminal connection 3 Housing / Negative terminal

[0055] 4 Seal

[0056] 5 Energy storage device 6 Connectors

[0057] 7 (Fused) fuse

[0058] 8 Support device / projection 9 Recess

Claims

24-2218 REQUIREMENTS 1. Battery cell (1) comprising a positive terminal (2) and a negative terminal (2) as well as a seal (4) which is arranged in a space between the positive terminal (2) and the negative terminal (2) and electrically insulates them from each other; wherein in the space between in an area without the seal (4) a support device (8) is arranged, the height of which is less than a distance between the positive pole and the negative pole (2), wherein the support device (8) is dimensioned and arranged such that the positive pole (2) and the negative pole in a fault case in which damage to the seal (4) causes the positive pole (2) and the negative pole (2) to come into close contact with each other, so that an electrically conductive contact between the positive pole (2) and the negative pole (2) is established by means of the support device.

2. Battery cell (1) according to claim 1, wherein the battery cell (1) has a housing and a terminal connection, wherein the negative terminal (2) or the positive terminal (2) is formed at least partially by the housing and wherein the other of the negative terminal (2) and of the positive terminal (2) is formed by the terminal connection.

3. Battery cell (1) according to claim 1 or 2, wherein the support device (8) is arranged at least partially in a recess of the seal (4).

4. Battery cell (1) according to one of the preceding claims, wherein the support device (8) has at least two support areas spaced apart from each other.

5. Battery cell (1) according to claim 4, wherein the support areas are uniformly distributed with respect to an extension of the support device (8).

6. Battery cell (1) according to one of the preceding claims, wherein the support device (8) has at least one projection which extends from at least one of the positive terminal (2) and the negative terminal (2) through the 24-2218 The space extends in the direction of the other of the positive pole (2) and the negative pole (2).

7. Battery cell (1) according to one of the preceding claims, wherein the support device (8) is designed such that the contact of the positive pole (2) and the negative pole (2) by means of the support device (8) is statically determined.

8. Energy storage device (5) comprising at least one battery cell (1) according to one of the preceding claims and at least one connector 6), wherein the battery cell (1) is electrically connected to at least one further component of the energy storage device (5) by means of the at least one connector (6), wherein the connector has an electrical fuse (7) which is configured to interrupt an electrical connection between the battery cell (1) and the at least one further component if a current applied to it is greater than a predetermined rated current of the fuse (7) for more than a predetermined period of time, wherein the support device (8) is configured such that a current defined by a current-carrying capacity of the support device (8) is greater than the rated current of the fuse (7).

9. Energy storage device according to claim 8, wherein the electrical fuse (7) is a fuse.

10. Electric vehicle with at least one energy storage device (5) according to claim 8 or 9 as a traction battery for an electric motor of the electric vehicle.

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