Battery system with degassing device

Abstract

Battery system (1), wherein the battery system (1) comprises a battery with a number of battery cells (3) or cell stacks forming at least one battery module (2), wherein the battery system (1) has a device provided with a plurality of degassing channels (4, 5) for degassing the battery and the associated battery cells (3) or cell stacks, wherein the degassing device comprises at least one pressure vessel (6) arranged spatially separated from the battery cells (3) and filled with an inert gas under excess pressure, wherein, in the event of gas escaping from the battery cells (3) or cell stacks, the pressure vessel (6) is connectable to the degassing channels (4, 5) in such a way that the inert gas flows out of the pressure vessel (6) and mixes with a gas discharge stream (7) flowing from the battery system in the degassing channels (4, 5), wherein at least one first degassing channel (4) leads away from the pressure vessel (6), wherein at least one second degassing channel (5) leads away from the at least one battery module (2), characterized in that the battery system (1) is a battery system in an electrically or partially electrically powered vehicle and the battery is a traction battery, a respective second degassing channel (5) is connected in a connection area (8) to a respective first degassing channel (4), wherein in the respective connection area (8) a gas discharge stream flowing out of the battery system (1) mixes with inert gas (9) flowing out of the pressure vessel (6), the connection region (8) of the connections of the first and second degassing channels (4, 5) are designed such that the gas discharge flow flowing out of the battery system (1) is accelerated and entrained by the inert gas (9) flowing out of the pressure vessel (6) by a suction or nozzle effect of the flowing out inert gas.

Description

[0001] The present invention relates to a battery system according to the preamble of claim 1. Also disclosed is a vehicle with such a battery system.

[0002] In addition to the traction battery, battery systems in electrically or partially electrically powered vehicles have a number of other devices for controlling and monitoring the system as well as a number of safety devices that ensure that controlled measures are taken to prevent damage in the event of an accident, unforeseen load or malfunction.

[0003] The main focus here is on safety against overheating and ignition. The drive or traction batteries of such battery systems store large amounts of energy thanks to the large number of individual battery cells arranged in parallel or series. With electrochemical energy storage, electrons are stored in the individual battery cells through a chemical reaction due to the charging current, and electrons are released during discharge through a reverse chemical reaction. The reactants are usually separated from one another by a layer permeable only to electrons or ions, so that they are not in direct contact with one another. Modern systems contain so-called pouch cells as individual cells, in which the electrochemically active elements of a cell - flat electrodes and electrolyte - are sealed between films in the form of a bag or pillow.Such pouch cells in particular are generally sensitive to mechanical damage and must therefore be protected by sturdy housings.

[0004] When the reactants of the battery cells come into direct contact with each other, with the oxygen in the air, with water or other substances, they can generate such great heat in a strong exothermic reaction that the battery cell or its components can ignite.

[0005] In the event of such a thermal event, i.e. overheating of cells, a large amount of hot gas is created, which must be removed from the cells and from the battery system. If, in the event of a thermal event, gas flows from one chamber containing cell stacks into another chamber containing cell stacks in high-performance traction batteries, this can also lead to the ignition of the cells or cell stacks in the other chamber. The spread of fires in a battery must therefore be contained locally, and the spread to neighboring cell stacks must be prevented or at least delayed. It is therefore crucial that the gas comes into contact with surrounding battery cells or battery cells arranged in other chambers as little as possible in order to prevent or at least delay the ignition of other cells. Degassing systems for the removal of hot vapors and gases are particularly useful for this purpose.

[0006] High-temperature gases that can arise during such a thermal event, escape from the battery cell, and are vented to the outside through degassing systems. They can ignite upon contact with oxygen, creating a flame. However, flame formation outside the vehicle must be avoided. One way to prevent flame formation is to cool the gas before it escapes from the vehicle. According to the state of the art, escaping gas in the event of damage is channeled through degassing channels and cooled by surface contact with the channels. Depending on the amount of gas, channel length, and material used, the channel heats up. As the temperature of the channel increases, the cooling effect on the gas decreases. Therefore, the amount of gas that can be cooled via a flow-through contact surface of a channel is limited.

[0007] DE 10 2013 200 739 A1 discloses a degassing system in which a fan is coupled to the degassing system in such a way that the fan increases the degassing performance or flow through the degassing system in the event of damage.

[0008] DE 2018 212 344 A1 discloses an electrochemical energy storage device composed of individual energy storage cells, which additionally contains individual pressure storage cells with inert compressed gas, the closure of which opens when a predetermined temperature threshold is exceeded.

[0009] JP 2004- 39 337 A discloses a battery system according to the preamble of claim 1.

[0010] CN 1 13 908 466 A and DE 10 2020 001 540 A1 disclose further prior art.

[0011] It is an object of the invention to provide a battery system with improved degassing, in particular with improved cooling of the gas.

[0012] This object is achieved by the features of claim 1. Advantageous embodiments and further developments are described in the respective dependent claims. A vehicle with such a battery system is also claimed.

[0013] The degassing device comprises at least one pressure vessel arranged spatially separate from the battery cells and / or battery modules containing battery cells and filled with an inert gas under excess pressure. In the event of gas escaping from the battery cells or cell stacks, the pressure vessel can be connected to the degassing channels in such a way that the inert gas flows out of the pressure vessel and mixes with a gas discharge stream flowing from the battery system in the degassing channels. Such mixing of the inert gas with the gas discharge stream dilutes and cools the latter, significantly reducing the risk of ignition.

[0014] At least one first degassing channel leads away from the pressure vessel. At least one second degassing channel leads away from the at least one battery module. Each second degassing channel is connected to a respective first degassing channel in a connection region, wherein in the respective connection region, a gas discharge stream flowing out of the battery system mixes with inert gas flowing out of the pressure vessel, and wherein the connection region of the connections of the first and second degassing channels is designed such that the gas discharge stream flowing out of the battery system is accelerated and entrained by the inert gas flowing out of the pressure vessel due to a suction or jet effect of the flowing inert gas.

[0015] The connection geometry of the degassing duct connections is therefore designed such that a gas discharge stream flowing out of the battery system is accelerated and entrained by the inert gas flowing out of the pressure vessel, specifically through a configuration in which the escaping inert gas creates a suction or jet effect. In the simplest case, such a configuration is sufficient to introduce the degassing ducts leading directly from the battery or battery module into the degassing duct carrying the escaping inert gas in the direction of flow in such a way that a drag effect occurs due to the flow forces.

[0016] An advantageous aspect of the invention is that the pressure vessel can be connected to the degassing channels via switchable valves and / or throttles, preferably via the valves and / or throttles that can be actively actuated / regulated via a control device. In particular, if, according to a further aspect of the invention, the valves and / or throttles can be actuated depending on sensor signals, preferably depending on signals from pressure or voltage sensors in the area of the degassing channels, battery cells, or cell stacks, an integrated safety circuit is created in which, depending on the pressure and temperature in the area of the battery system, measures can be initiated by a correspondingly programmed control device that prevent the gas from igniting early and reliably.

[0017] A further development of the invention consists in the valves and / or throttles being assigned to one or more connecting lines between the pressure vessel and the degassing ducts. This allows the degassing device and the installation location of the pressure vessel to be easily adapted to the specific vehicle design. For this purpose, several degassing ducts can be arranged in the vehicle. Several connecting lines with actively controllable valves and / or throttles can also lead from the pressure vessel into the degassing ducts and be connected to them.

[0018] A further development of the invention consists in storing the pressure vessel in a vehicle compartment at ambient temperature. This ensures that the temperature of the inert gas before it is introduced into the degassing duct is already well below the temperature of the escaping gases, so that cooling occurs solely through this process.

[0019] In particular, in connection with a further aspect of the invention, which consists in the fact that the overpressure in the pressure vessel is preferably at least 10 bar higher than the ambient pressure, a further cooling of the gas discharge stream results, namely through the isenthalpic expansion of the inert gas when the valves are opened and the resulting strong cooling of the introduced inert gas.

[0020] Another aspect of the invention is that the inert gas is nitrogen or a noble gas, preferably helium, neon, argon, krypton, or xenon, a gaseous molecular compound such as sulfur hexafluoride, or a mixture of various inert gases. Such gases are readily available and easy to handle and work with commercially available valves and fluid control elements.

[0021] A further development of the invention consists in that the traction battery has a plurality of individually sealed, electrically interconnected battery modules, each with a number of battery cells or cell stacks, wherein a battery module is connected to at least one of the degassing channels.

[0022] In the prior art, the term and object "battery module" is often defined differently than the traction battery or the power storage device / accumulator as a whole, but always includes a combination or a number of interconnected individual battery cells. In the following, the definition is that a traction or drive battery is made up of battery modules, with each battery module forming a housing with chambers in which individual battery cells or cell stacks are arranged. The battery modules protect the battery cells or cell stacks not only from mechanical stress, particularly in the event of a crash, but also from environmental influences. They should be watertight, gas-tight, and, what is particularly important, fireproof. The aforementioned embodiment of the invention, in which each battery module is connected to at least one venting duct, takes fire protection into particular account.

[0023] A further aspect of the invention relates to an electrically or partially electrically driven vehicle with a battery system according to the invention, in which the traction battery or individual battery modules extend across the vehicle width between the two sills of the body and in which at least one degassing channel is provided in the area of each sill.

[0024] Such an arrangement provides extremely good accessibility to the individual components of the degassing system without compromising safety. The degassing ducts, connecting lines, and valves / throttles are then accessible from the exterior and underside of the vehicle and can be easily repaired or replaced, for example.

[0025] In the following, the invention is described with reference to the exemplary embodiment shown in the figures of the drawing. Fig. 1 in the form of a functional sketch the essential parts of a battery system according to the invention, Fig. 2 a functional sketch of a battery system according to the invention with a traction battery composed of several individually sealed battery modules.

[0026] In the figures, identical or similar elements may be referenced with the same reference numerals.

[0027] Fig. Figure 1 shows, in the form of a functional diagram, the essential parts of a battery system 1 according to the invention. Shown here is one of the battery modules 2 belonging to the traction battery with a number of battery cells or cell stacks 3. The battery system 1 has a device for degassing the traction battery. Several interacting degassing channels 4, 5 are assigned to the degassing device. The degassing channel 5 leads from the battery module to another degassing channel 4, which also receives the inert gas flowing out of the pressure vessel 6. The flow direction that occurs during degassing, or the gas discharge flow (gas and / or a mixture of gas and inert gas), is represented by arrows 7, and the inert gas flow from the pressure vessel is represented by arrow 9.

[0028] As can be clearly seen, the pressure vessel 6 is arranged spatially separated from the battery cells or, in this case, from the battery module 2.

[0029] The pressure vessel 6 is stored in a vehicle area that is regularly at ambient temperature. In the event of gas escaping from the battery cells 3 or cell stacks, the pressure vessel 6 can be connected to the degassing channels 4, 5 in such a way that the inert gas flows out of the pressure vessel in the flow direction 9 and mixes with a gas discharge stream 7 flowing from the battery system in the degassing channels.

[0030] The overpressure of the inert gas in the pressure vessel is, for example, 10 bar higher than the ambient pressure, which means that the pressurized inert gas experiences additional cooling due to the Joule-Thomson effect as it flows out and relaxes.

[0031] The connection geometry of connections of the degassing channels, here the geometry of the connection area 8, is designed such that a gas discharge stream 7 flowing out of the battery system via the degassing channel 5 is accelerated and entrained by the inert gas 9 flowing out of the pressure vessel, namely by a suction or jet effect of the flowing inert gas 9 generating the connection area 8. In the embodiment shown here, this is achieved by a correspondingly designed T-shaped opening of the gas channel 5 into the gas channel 4, whereby the flowing inert gas 9 creates an additional suction effect on the gas discharge stream 7 emerging from the degassing channel 5.

[0032] In conjunction with the Fig. 2 clearly shows that the pressure vessel 6 can be connected to the degassing channels 4, 5 via switchable valves and / or throttles 10, wherein the valves and / or throttles can be actively actuated / regulated via a control device 12. The valves and / or throttles 10 are arranged in supply lines 11 that lead from the pressure vessel 6 to the beginning of the degassing channels 4 and can be controlled / regulated depending on sensor signals from the pressure or voltage sensors 13 arranged in or on the battery modules 2.

[0033] Also in the Fig. 2 that the battery system comprises a traction battery composed of several individually sealed battery modules 2. Each battery module is connected on the left side and in time to one of the degassing channels 5, which open in a T-shape into a left-side and a right-side degassing channel 4.

[0034] The Fig.The traction battery of an electrically or partially electrically powered vehicle shown in Figure 2 belongs to a battery system whose individual battery modules 2 are arranged one behind the other and extend essentially across the vehicle width 14 between the two sills of the body. Thus, a degassing duct 4 is provided in the area of each left-hand and right-hand sill. For orientation, the direction of travel of the vehicle (not shown here) is indicated by arrow 15. List of reference symbols 1 battery system 2 battery module 3 battery cells / cell stacks 4 Degassing channel 5 Degassing channel 6 pressure vessels 7 Gas discharge stream, gas or gas mixture 8 Connection geometry of the degassing ducts 9 escaping inert gas, flow direction of the inert gas 10 Valve and / or throttle 11 Supply line 12 Control device 13 Pressure or voltage sensor 14 vehicle width 15 Direction of travel

Claims

[1] Battery system (1), wherein the battery system (1) comprises a battery with a number of battery cells (3) or cell stacks forming at least one battery module (2), wherein the battery system (1) has a device provided with a plurality of degassing channels (4, 5) for degassing the battery and the associated battery cells (3) or cell stacks, wherein the degassing device comprises at least one pressure vessel (6) arranged spatially separated from the battery cells (3) and filled with an inert gas under excess pressure, wherein, in the event of gas escaping from the battery cells (3) or cell stacks, the pressure vessel (6) is connectable to the degassing channels (4, 5) in such a way that the inert gas flows out of the pressure vessel (6) and mixes with a gas discharge stream (7) flowing from the battery system in the degassing channels (4, 5), wherein at least one first degassing channel (4) leads away from the pressure vessel (6), wherein at least one second degassing channel (5) leads away from the at least one battery module (2), characterized by , that the battery system (1) is a battery system in an electrically or partially electrically powered vehicle and the battery is a traction battery, a respective second degassing channel (5) is connected in a connection area (8) to a respective first degassing channel (4), wherein in the respective connection area (8) a gas discharge stream flowing out of the battery system (1) mixes with inert gas (9) flowing out of the pressure vessel (6), the connection region (8) of the connections of the first and second degassing channels (4, 5) are designed such that the gas discharge flow flowing out of the battery system (1) is accelerated and entrained by the inert gas (9) flowing out of the pressure vessel (6) by a suction or nozzle effect of the flowing out inert gas. [2] Battery system according to claim 1, wherein the pressure vessel (6) can be connected to the degassing channels (4, 5) via switchable valves and / or throttles (10), preferably via the valves and / or throttles (10) which can be actively actuated / regulated via a control device (12). [3] Battery system according to claim 2, wherein the valves and / or throttles (10) can be actuated depending on sensor signals, preferably depending on signals from pressure or voltage sensors (13) in the region of the degassing channels, battery cells or cell stacks. [4] Battery system according to one of claims 2 to 3, in which the valves and / or throttles (10) are assigned to one or more connecting lines (11) between the pressure vessel (6) and the degassing channels (4). [5] Battery system according to one of claims 1 to 4, wherein the pressure vessel (6) is stored in a vehicle area at ambient temperature. [6] Battery system according to one of claims 1 to 5, wherein the overpressure in the pressure vessel (6) is preferably at least 10 bar higher than the ambient pressure. [7] Battery system according to one of claims 1 to 6, wherein the inert gas is nitrogen or a noble gas, preferably helium, neon, argon, krypton, or xenon, a gaseous molecular compound such as sulfur hexafluoride or a mixture of different inert gases. [8] Battery system according to one of claims 1 to 7, wherein the traction battery has a plurality of individually sealed battery modules (2), each having a number of battery cells or cell stacks, wherein a battery module is connected to at least one of the degassing channels (5). [9] Electrically or partially electrically driven vehicle with a battery system according to one of claims 1 to 8, in which the traction battery or individual battery modules (2) extend across the vehicle width (14) between the two sills of the body and in which at least one degassing channel (4) is provided in the region of each sill.

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