Battery cell with improved rupture protection

Abstract

The invention relates to a battery cell, comprising: a cover assembly (1), a housing (11), a rupture device (7) which is designed to conduct a fluid and / or particles from the battery cell to the outer side of the battery cell, and a discharge element (8) for discharging from the battery cell the fluid and / or particles which exit the rupture device (7), wherein the discharge element (8) is arranged above the rupture device (7) and surrounds the rupture device in the circumferential direction in order to have a discharge path for fluid and / or particles exiting the rupture device (7) without contact with a component surrounding the battery cell and / or surrounding cooling fluid.

Description

[0001] January 12, 2026

[0002] Mat exchange

[0003] Applicant: Carl Freudenberg KG, 69469 Weinheim

[0004] Battery cell with improved burst protection

[0005] Description

[0006] The present invention relates to a battery cell with improved burst protection, in particular in the case of immersion cooling with an immersion fluid, and to a battery arrangement with such a battery cell equipped.

[0007] Battery arrays often contain a large number of battery cells that require cooling. One cooling method is immersion cooling, in which an immersion fluid is circulated around the battery cells within a housing of the battery array for cooling purposes. These immersion fluids are often flammable. Furthermore, thermal runaways can occur in individual battery cells, leading to critical overpressures during operation. To address this, battery cells are equipped with rupture devices that release degradation products formed within the cell to the outside. These products can include non-flammable mixtures of gaseous degradation products, such as carbon dioxide, as well as flammable gases, such as CO, hydrogen, and / or hydrocarbons, and particulate solids.Ceramic particles from the electrode materials, graphite or metal particles from the heat sinks, as well as droplets of molten metals such as aluminum or lithium, can escape from the battery cell in a burst of flame. This poses a risk of igniting components in the immediate vicinity of the cell, and especially of igniting other cells. This so-called propagation ultimately leads to the complete destruction of the vehicle. In immersion cooling systems, there is also the risk of the immersion fluid igniting, which further intensifies the battery fire.

[0008] It is therefore an object of the present invention to provide an improved battery cell and an improved battery arrangement, particularly for immersion cooling, which are simple and cost-effective to manufacture and in which ignition of a cooling fluid surrounding the battery cell cannot occur. This object is achieved by a battery cell with the features of claim 1 and a battery arrangement with the features of claim 12. The dependent claims describe preferred embodiments of the invention.

[0009] The battery cell according to the invention, with the features of claim 1, has the advantage that it enables the safe discharge of gases and other fluids and particles that are generated within the battery cell during operation and are released to the outside of the battery cell, outside of any cooling fluid, via a rupture device. Both flammable and non-flammable gases, fluids, and particles can be safely discharged in this way. In particular, when the battery cell is cooled with a flammable cooling fluid located outside the battery cell, this prevents the flammable cooling fluid from igniting and thus potentially causing it to burn.

[0010] According to the invention, this is achieved by the battery cell having a cover assembly and a housing. The battery cell further comprises a rupture device, in particular a rupture disc, which, especially in the event of an emergency, can discharge fluids and particles from the interior of the battery cell to the outside of the battery cell. The battery cell also comprises a discharge element for discharging the fluids and particles escaping from the rupture device. The discharge element is arranged in a fluid-tight manner above the rupture device and is located in the immediate vicinity of the battery cell. The discharge element surrounds the rupture device circumferentially to provide a discharge path for the fluid escaping from the rupture device and to lead it to an area outside of any cooling fluid surrounding the battery cell, in particular a flammable coolant. The discharge element preferably leads to an exterior surface where no flammable media are present.The deflector element is preferably made of a non-combustible material or a material that is difficult to ignite.

[0011] Particularly safe drainage of fluids from the interior of the battery cell in the event of rupture at the rupture device is possible if the drainage element includes a tube. The tube is made of a rigid material and offers maximum safety when draining hazardous fluids from the battery cell. Furthermore, the tube can be easily positioned above the rupture device. The tube can have any desired cross-section. Alternatively, the drainage element includes a flexible hose. This allows for a particularly simple drainage path by appropriately positioning the flexible hose to the outside. In addition, tolerance compensation is improved. Preferably, the drainage element is multi-walled, especially with a thermal insulation layer. This ensures thermal insulation from the immersion fluid.Furthermore, this allows for a redundant function; if an inner wall is damaged, an outer wall takes over the sealing of the escaping media. Additionally, any seal on the outer perimeter is better thermally protected.

[0012] Alternatively, the drainage element can also include a bellows. Like the hose, the bellows offers the advantage of high flexibility and can therefore be used in a wide variety of applications.

[0013] Preferably, the bursting device is arranged in the cover assembly and / or in the housing.

[0014] The discharge element is preferably made of metal, plastic, or a non-combustible, flexible material. The discharge element is preferably made of a material that has a melting point or decomposition temperature > 400 °C.

[0015] Preferably, the discharge element is firmly connected to the cover assembly or the housing by means of a material-bonded connection, in particular a welded connection. Alternatively, a force-fit and / or form-fit connection is provided.

[0016] Preferably, the battery cell further comprises a lid element that closes the discharge element, creating a sealed space within the discharge element. That is, the sealed space exists between the lid element and the bursting device within the discharge element. This prevents particles, dust, or similar substances from accumulating above the bursting device and hindering or completely preventing a necessary bursting action. Preferably, the sealed space is filled with non-flammable or flame-resistant media. For example, the sealed space can be filled with water or an inert gas, such as nitrogen or a noble gas.This has the advantage that if the bursting device opens and flames escape, the flames can be smothered by the medium in the enclosed space, or at least the flame height exiting the discharge element can be reduced. This provides the battery cell with an additional safety feature, significantly reducing the risk of a full-scale fire in which a large number or all battery cells ignite. Preferably, the lid element is designed to be destroyed or removed from the discharge element when the bursting device opens. Destruction can occur, for example, due to temperature, particularly by melting or burning the lid element, or due to pressure, for example, by the lid element being blown off when a predetermined pressure is present in the discharge element. The lid element is preferably a film or a molded part.The cover element is preferably arranged directly at an outer opening of the drainage element or set back slightly from the outer opening in the drainage element.

[0017] Preferably, the battery cell includes a seal arranged on the outer circumference of the discharge element. The seal is designed to be positioned between the discharge element and an outer housing and can compensate for tolerances between the discharge element and the outer housing.

[0018] Furthermore, the present invention relates to a battery arrangement comprising a battery cell according to the invention, an outer casing, and a cooling system with a cooling fluid. The cooling fluid cools the battery cell on its outer surface, wherein the discharge element of the battery cell establishes a connection between the bursting device and an external environment of the battery arrangement.

[0019] The cooling fluid of the battery assembly's cooling system is preferably an immersion fluid. This allows for immersion cooling of the battery cell, which enables high cooling capacity in a compact design. The immersion fluid is electrically non-conductive and is, for example, a mineral oil or a synthetic oil.

[0020] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawing. The drawing shows:

[0021] Fig. 1 shows a schematic view of a battery arrangement with one battery cell according to a first embodiment of the invention.

[0022] Fig. 2 shows a schematic view of a battery arrangement with one battery cell according to a second embodiment of the invention.

[0023] Fig. 3 shows a schematic view of a battery arrangement with one battery cell according to a third embodiment of the invention.

[0024] Fig. 4 is a schematic view of a battery arrangement with one battery cell according to a fourth embodiment of the invention, Fig. 5 is a schematic view of a battery arrangement with one battery cell according to a fifth embodiment of the invention, and

[0025] Fig. 6 shows a schematic view of a battery arrangement with one battery cell according to a sixth embodiment of the invention.

[0026] Preferred embodiments of the invention are described in detail below with reference to the accompanying figures. In the figures, identical or functionally equivalent parts are designated by the same reference numerals.

[0027] Figure 1 shows a battery arrangement 12 with a battery cell 10 according to a first preferred embodiment of the invention.

[0028] The battery cell 10 is a prismatic battery cell and has a cover assembly 1 and a housing 11. The cover assembly 1 closes the housing 11.

[0029] The cover assembly 1 is shown schematically and comprises a metallic base plate 2, a first terminal 3, a second terminal 4 and a filling opening 6. The filling opening 6 is used to fill the battery cell 10 with an electrolyte and is closed with a plug or the like after the filling process.

[0030] The first terminal 3 is a cathode and the second terminal 4 is an anode. A bursting device 7 is arranged longitudinally between the first terminal 3 and the second terminal 4 of the cover assembly 1.

[0031] The bursting device 7 is designed to burst at designated bursting structures 70, which create a reduced thickness on the bursting device 7, when overpressure occurs inside the battery cell 10. This allows a pressurized medium and / or particles to escape from the battery cell 10 through the bursting bursting device 7.

[0032] The battery cell 10 of this embodiment is arranged in a battery assembly 12 with an outer casing 13. The battery assembly 12 features immersion cooling, with a cooling fluid 14 located inside the outer casing 13. The cooling fluid 14 is an immersion fluid and directly surrounds the battery cell 10.

[0033] The battery cell 10 further comprises a discharge element 8. As can be seen from Figure 1, the discharge element 8 is arranged above the bursting device 7. The discharge element 8 is designed to discharge fluids and particles that escape from the bursting device 7.

[0034] The discharge element 8 of this embodiment comprises a rigid tube 80. The tube 80 is arranged fluid-tight over the bursting device 7 on the base plate 2 by means of a welded connection 9. Thus, fluids and particles that escape from the bursting device 7 of the battery cell 10 can be fed into the tube 8 and from there conveyed through the tube 80 to an outer surface 15 of the outer housing 13 of the battery assembly 12. This is indicated by arrow A in Figure 1. The discharge element 8 therefore prevents fluids and particles escaping from the bursting device 7 from coming into direct contact with the cooling fluid 14, which may be flammable. The discharge element 8, in the form of the tube 80, can be provided very simply and cost-effectively. The tube 80 can be made of various materials, preferably a metal, a thermoset, or another thermally stable plastic.

[0035] The passage of the tube 80 through the outer casing 13 can be configured in various ways. Preferably, a metal-bonded connection, in particular a welded connection to the outer casing 13, is formed, which is gas-tight. The tube can be flush with an outer surface of the outer casing 13, as shown in Fig. 1, or it can protrude from the outer casing 13.

[0036] Preferably, an outer opening of the tube 8 is protected by a cover element. The cover element can, for example, be a film that melts at a certain temperature and thus exposes the outer opening of the tube 8, or a molded part that is forced out of the opening of the tube by the internal overpressure in the tube 8 at a predetermined pressure level.

[0037] If the bursting device is oval-shaped, as shown in Figure 1, the discharge element 8 has a cross-section corresponding to a bursting opening. Alternatively, a funnel-shaped area on the tube 80 is conceivable, which is shaped according to the outer circumference of the bursting device and transitions into a cylindrical cross-section.

[0038] Preferably, the bursting device 7 comprises plates or similar components integrated into the bursting device 7, which deflect, widen, and / or distribute an emerging flame jet. This can, for example, reduce the flame height emerging from the outer opening of the pipe.

[0039] Thus, by integrating the drain element 8 into the cover assembly 1, a surprisingly simple and absolutely safe drainage of fluids escaping from the bursting device 7 can be achieved. This prevents the risk of ignition of the cooling fluid 14 of the battery assembly 12. Figure 2 shows a second embodiment of the invention, wherein the drain element 8 of the second embodiment comprises a flexible hose 81. The flexible hose has the advantage that particularly simple assembly and an absolutely flexible arrangement of a drain path through the hose are possible. The hose is preferably made of a flexible, thermally stable material, e.g., an elastomer. This allows for particularly simple tolerance compensation.

[0040] Figure 3 shows a third embodiment in which the deflector element 8 comprises a bellows 82. The bellows 82 also exhibits very good flexibility and is preferably made of an elastic, thermally stable material.

[0041] Figure 4 shows a fourth embodiment in which the prismatic battery cell 10 has two cover assemblies 1, each arranged on one of the two short narrow sides of the battery cell 10. Each of the two base plates 2 of the cover assemblies 1 has a filling opening 5, 6. A bursting device 7 is arranged on one long narrow side of the battery cell 10. As in the previous embodiments, a drain element 8 is arranged fluid-tight over the bursting device 7 by means of a welded connection 9. In the fourth embodiment shown, the drain element 8 comprises a tube 80. However, the drain element 8 can also comprise a hose 81 or a bellows 82.

[0042] Fig. 5 shows a fifth embodiment in which the battery cell 10 is designed as a cylindrical cell. The rupture device 7 is arranged on the underside of the cylindrical cell. As in the previous embodiments, a discharge element 8, shown in this embodiment as a tube, is arranged below the rupture device 7 to provide a closed discharge path to an outer surface of the outer casing. Here, the discharge element 8 is closed by means of a cover element 20, in this embodiment a foil 21. This creates a closed space 18 in the discharge element 8 between the rupture device 7 and the cover element 20. A non-flammable medium or a low-flammability medium, such as water or an inert gas, is arranged in the closed space 18. This gives the battery cell 10 an additional safety function.The flame-resistant medium in the enclosed space 18 can, in the event of a bursting of the bursting device 7 and flames escaping from it, at best extinguish the flames or at least reduce the height of the escaping flames. This reduces the height of the flames exiting the opening of the discharge element 8, thus significantly reducing the risk of flame spread. The foil 21 can melt or even burn due to a temperature-related effect, thereby opening the discharge element 8 in an emergency.

[0043] Fig. 6 shows a sixth embodiment of the invention, which, as in the fifth embodiment, has an additional cover element 20 at an outer opening of the discharge element 8. The cover element 20 of the sixth embodiment is a molded part 22 that closes the opening of the discharge element 8. The molded part 22 can, for example, be blown off the discharge element 8 by an increased pressure in the enclosed space 18 when the bursting device 7 bursts. As in the fifth embodiment, it is also possible for the enclosed space 18 to be filled with a non-flammable or flame-retardant medium for flame reduction and / or flame suppression. Furthermore, in the sixth embodiment, a cooler 17 is arranged between the outer housing 13 and the battery cell 10. Here, the discharge element 8 is guided through a through-opening in the cooler 17 to the outer surface 15. As in Fig.As shown in Figure 6, the discharge element 8 projects slightly beyond the outer housing 13. This allows, in particular, the direction of discharge for the medium exiting the battery cell when the bursting device bursts to be set, for example, by directing the protruding discharge element 8 in a direction where no easily flammable components or materials are present. Furthermore, the battery cell 10 has a seal 16, which, as can be seen in Figure 6, is arranged between the discharge element 8 and the outer housing 13. The seal 16 is made of an elastomer material and, in the simplest case, is an O-ring seal. This allows for tolerance compensation between the discharge element 8 and the outer housing 13.

[0044] As illustrated in the exemplary embodiments, a simple and safe discharge system for fluids, particularly gases, escaping from a ruptured rupture device 7 can be provided to an external surface 15 of the battery assembly 12. Rigid discharge systems, such as a pipe, or flexible discharge systems, such as hoses or bellows, can be used. In all exemplary embodiments, enclosed spaces 18, as shown in the fifth and sixth exemplary embodiments, can also be provided.

Claims

9 Claims 1. Battery cell, comprising: a lid assembly (1), a case (11), a bursting device (7) which is configured to discharge fluid and / or particles from the battery cell to the outside of the battery cell, and a drain element (8) for draining the fluid and / or particles from the battery cell which escape from the bursting device (7), wherein the discharge element (8) is arranged above the bursting device (7) and surrounds the bursting device in the circumferential direction in order to have a discharge path for fluid and / or particles escaping from the bursting device (7) without contact with the components surrounding the battery cell and / or surrounding cooling fluid.

2. Battery cell according to claim 1, wherein the discharge element (8) comprises a tube (80).

3. Battery cell according to claim 1, wherein the discharge element (8) comprises a flexible tube.

4. Battery cell according to claim 1, wherein the discharge element (8) comprises a flexible bellows.

5. Battery cell according to one of the preceding claims, wherein the bursting device (7) is arranged in the lid assembly (1) and / or in the housing (11).

6. Battery cell according to one of the preceding claims, wherein the discharge element (8) is made of metal, in particular aluminium or steel, or of plastic, in particular a thermoset or an elastomer.

7. Battery cell according to one of the preceding claims, wherein the discharge element (8) is fixed over the bursting device (7) by means of a weld connection (9).

8. Battery cell according to one of the preceding claims, further comprising a lid element (20), in particular a film or a shaped element which closes the discharge element (8) so that a closed space (18) is formed in the discharge element (8).

9. Battery cell according to claim 8, wherein the enclosed space (18) is filled with a non-flammable medium or a low-flammability medium, in particular water or an inert gas.

10. Battery cell according to claim 8 or 9, wherein the lid element (20) is configured to be destroyed or removed from the discharge element (8) when the bursting device (7) is opened.

11. Battery cell according to one of the preceding claims, further comprising a seal (16) which is arranged on an outer circumference of the discharge element (8) to enable tolerance compensation between the discharge element (8) and a further component.

12. Battery arrangement comprising: a battery cell (10) according to one of the preceding claims, - an outer casing (13) in which the battery cell (10) is arranged, and a cooling system with a cooling fluid for cooling the battery cell (10) on an outside of the battery cell, wherein the discharge element (8) of the battery cell provides a connection between the battery cell and an outer surface (15) of the battery assembly.

13. Battery arrangement according to claim 12, wherein the cooling system is an immersion cooling system with an immersion fluid, in particular a flammable one.

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