Battery system and motor vehicle having the battery system

Abstract

A battery system (10) having a plurality of battery cells (12) arranged in a battery housing (16), with each battery cell (12) having a cell housing (18) and / or the battery housing (16) having at least one exhaust opening (20) through which an air flow can be released along a predetermined exhaust path (26) into the surroundings of the battery cell (12) and / or the battery system (10). A spark arrestor device (24) prevents sparks and / or particles from flowing with the air flow into the surroundings and igniting the air flow in the surroundings. The spark arrestor device (24) also additionally serves as a heat exchanger for the air flow here. The spark arrestor device is designed to decelerate the air flow and guide the air flow along the surface of the spark arrestor device (24), such that the air flow flows along the surface for at least a predetermined duration. Thereby, heat output energy is extracted from the air flow so that the temperature value of the air flow upon release into the surroundings drops below a predetermined temperature limit value.

Description

Technical Field

[0001] The present invention relates to a battery system and a motor vehicle having the battery system. Background Art

[0002] In the sense of the present invention, a battery system includes a plurality of individual battery cells, which are arranged in a battery housing of the battery system. Each battery cell can be configured as a pouch cell, a prismatic cell or a cylindrical cell. Known battery cells of the above types include galvanic cells, wherein the galvanic cell has an anode and a cathode, which are electrically insulated from each other by a separator or a separator film and can be arranged to form a cell roll. The cell roll is surrounded by a cell housing of the corresponding battery cell and is immersed in an electrolyte or an electrolyte solution. Such a battery cell can provide a voltage between 3 volts and 5 volts, especially between 3.5 volts and 4.5 volts. A plurality of battery cells of such a battery system can be electrically connected in series and / or in parallel to provide a voltage and a current suitable for supplying power electrical energy to at least a partially electrically driven motor vehicle.

[0003] It is known that a cell failure in the galvanic cell or an aging process in the galvanic cell causes gas to be generated in the interior space of the corresponding cell housing. In order to reduce the increased cell pressure due to gas generation, known cell housings and / or battery housings have exhaust openings or rupture openings through which the gas can be discharged into the surroundings of the battery cell and / or the battery system. Depending on the main cell chemical components present in the galvanic cell involved, the flammability of the gas increases when exposed to ambient air. In addition, the cell chemistry affects the temperature of the gas. Depending on the cell chemical components, the gas temperature can be as high as 1500 degrees Celsius.

[0004] In order to prevent such gas from being ignited by a flame entering the cell housing and / or the battery housing from the outside, documents GB1355831 and WO 2013 / 128226 A1 respectively propose spark blocking devices / safety plugs (Flammensperren).

[0005] However, the flame-ignitable gas entering the single cell housing from the outside is not the only problem. As is well known, particles and / or sparks may be entrained in the formed gas. If such an air stream with particles and / or sparks comes into contact with ambient air that is oxygen-rich relative to the battery environment or the interior of the battery, the air stream may be ignited by the entrained sparks. As a solution to this problem, document EP 2 849 257A1 provides a spark blocking device arranged at the exhaust opening for filtering the sparks in the air stream. The disadvantage here is that although the air stream may be cleared of sparks and / or particles after passing through the spark blocking device, the air stream generally still has a temperature that may be sufficient to cause the air stream to spontaneously combust suddenly when it comes into contact with oxygen-rich ambient air. Summary of the Invention

[0006] The object of the present invention is to further improve the operating safety of a battery system of the type described at the beginning in the case of gas escape.

[0007] According to the present invention, there is provided a battery system having a plurality of battery cells arranged in a battery housing. Each battery cell has a cell housing that at least partially surrounds the galvanic cell. In other words, each battery cell includes at least one galvanic cell, wherein the at least one galvanic cell is at least partially surrounded by the cell housing. The battery cells can be pouch cells, prismatic cells or cylindrical cells. The cell housing and / or the battery housing of the battery system has at least one exhaust opening that is designed to allow an air stream to be released from the interior space of the cell housing and / or the battery housing along a predetermined exhaust path into the surroundings of the battery cell and / or into the surroundings of the battery system. In other words, the cell housing of the corresponding battery cell and / or the battery housing of the battery system provides a mechanically and / or structurally and / or materially weak part that allows the gas to flow out in a regulated or predetermined manner in the case of gas generation described at the beginning. For the case where the exhaust opening is arranged in the housing wall of the cell housing, the air stream first escapes from the battery cell into the interior space of the battery housing. If the battery housing also has at least one such exhaust opening, the gas escaping from the battery cell in the interior space of the battery housing can also be guided - in particular along the predetermined exhaust path - to the at least one exhaust opening of the battery housing and released through this exhaust opening into the surroundings of the battery housing. Along the exhaust path, there is a spark blocking device that is designed to filter out or retain sparks and / or particles from the air stream.

[0008] According to the present invention, the spark arrester is designed to perform, in addition to the filtering function, a heat exchange function. In other words, the spark arrester is designed to act as a heat exchanger. For this purpose, the spark arrester is designed such that it reduces the flow velocity of the air stream compared to the initial velocity and thus decelerates the air stream. Additionally, the spark arrester also guides the air stream along the surface of the spark arrester. This can be achieved by means of channels along the surface, which on the one hand increases the surface area and on the other hand also exerts a turning or guiding action on the air stream. By decelerating, the air stream is retained within the spark arrester for a predetermined duration, so that heat exchange occurs between the air stream and the material of the spark arrester. In other words, the spark arrester is designed to reduce the flow velocity of the air stream and guide the air stream along the surface of the spark arrester such that the air stream flows along the surface for at least a predetermined duration.

[0009] According to the present invention, the duration, the surface area, and the reduced flow velocity are coordinated with each other in such a way that heat output energy is extracted from the air stream so that the temperature value of the air stream when released into the surrounding environment drops below a predetermined temperature limit value. Here, there is in particular a degree of freedom in the design of the surface of the spark arrester. The heat extraction power of the surface for the thermal energy of the air stream varies depending on the choice of the geometry of the surface and / or the material. For example, if a material with high thermal conductivity is selected for the surface, the duration for which the air stream has to flow along the surface can be reduced. Thereby, a high degree of flexibility is obtained with respect to making the best possible use of the available construction space.

[0010] According to the present invention, heat exchange takes place on the surface of the spark arrester and / or via the length of the flow path inside the spark arrester. Thereby, it is advantageously achieved that the temperature of the air stream drops when it comes into contact with the ambient air to a level that prevents spontaneous combustion of the gas. Since the dimensions of the spark arrester are determined in relation to the autoignition temperature of the gas that may escape, it is not necessary to actively regulate the heat exchange. That is, the temperature measurement of the gas before it is released into the surrounding environment can be dispensed with, because the design of the spark arrester ensures that the gas is cooled to or already cooled to a value below the corresponding autoignition temperature of the gas when it escapes into the surrounding environment. The advantage resulting therefrom is that the entire heat exchange system can be operated particularly with low wear and reliability.

[0011] The present invention also includes embodiments that produce additional advantages.

[0012] One embodiment proposes that a galvanic cell includes an electrolyte having a predetermined chemical composition, wherein a predetermined temperature limit is determined based on at least one monomer chemical parameter in the chemical composition. For example, the chemical composition may describe the ratio of nickel:manganese: cobalt. For example, the ratio may be 8:1:1. Depending on the ratio of the respective element contents to each other, the air flow discharged from such a galvanic cell may result in different autoignition temperatures. Therefore, depending on the electrolyte used, different temperature limits may occur, wherein through the design of a spark arrestment device having a heat exchange function, it is ensured that the air flow is below the respective temperature limits when released into the surrounding environment of the battery system.

[0013] Another embodiment proposes that the spark arrestment device at least partially has a sponge structure with open pores, wherein the open pores are designed to allow air flow to pass through the pores. Therefore, the spark arrestment device can be at least partially formed of a foamed material, such as foamed glass. In particular, materials of ceramics and / or glass ceramics can be foamed in such a way that the material provides open pores through which air flow can pass. This results in the advantage of particularly simple manufacture of the spark arrestment device.

[0014] According to another embodiment, the spark arrestment device at least partially has a fabric made of glass fiber-based and / or ceramic materials.

[0015] Alternatively or additionally, the spark arrestment device can at least partially have oriented and / or non-oriented fibers, such as glass fibers. Fibers of this type can be woven to form a framework, thereby providing an ordered fabric or at least a locally disordered non-woven fabric.

[0016] According to a particularly advantageous embodiment, the spark arrestment device is at least partially woven from metal wires. The metal wires can have higher thermal conductivity compared to the surrounding material, and through the metal wires, the thermal energy of the air flow can be directed or spatially restricted along the spark arrestment device. Additionally, the metal wires give the spark arrestment device greater mechanical strength, so that the kinetic energy of particles and / or sparks in the air flow can be absorbed particularly effectively in an advantageous manner. For example, a mesh fabric made of metal wires can be provided, wherein, for example, the above-mentioned foamed material and / or at least locally a non-woven fabric made of glass fibers can be arranged within the woven mesh.

[0017] Another embodiment proposes that the spark arrestment device is arranged on the side of the monomer housing and / or the battery housing facing away from the environment and / or the side facing the environment. In other words, the spark arrestment device can be arranged inside or outside the respective housing, or on both sides with respect to the respective housing wall. The resulting advantage is that the spark arrestment device can be flexibly arranged according to the existing structural space.

[0018] Preferably, at least one exhaust opening can be closed by a rupture element, which can be designed, for example, as a rupture membrane or a rupture disk. The advantage resulting therefrom is that the kinetic energy can be intercepted at least partially by the rupture element before the gas flow hits the spark arrester.

[0019] Furthermore, the invention relates to a motor vehicle having a battery system according to the invention.

[0020] The invention also includes improvements to the motor vehicle according to the invention, the improvements having the features as already described in connection with the improvements to the battery system according to the invention. For this reason, the corresponding improvements to the motor vehicle according to the invention are not described here again.

[0021] The motor vehicle according to the invention is preferably designed as a motor car, in particular a saloon car or a lorry, or as a passenger bus or a motorcycle.

[0022] The invention also includes combinations of the features of the described embodiments. Description of the Drawings

[0023] Embodiments of the invention are described below. For this purpose, it is shown:

[0024] Figure 1 A schematic view of an embodiment of a battery cell according to the invention, the battery cell having a spark arrester and an exhaust opening inside the battery housing;

[0025] Figure 2 A schematic view of an embodiment of a battery cell arrangement inside a battery system housing, the battery system housing having exhaust openings arranged opposite one another. Detailed Description of the Invention

[0026] The embodiments described below are preferred embodiments of the invention. In the examples, the parts of the described embodiments are each features of the invention that can be considered independently of one another, and these features also improve the invention independently of one another. Therefore, the present disclosure should also include combinations of the features of the embodiments other than the combinations shown. In addition, the described embodiments can also be supplemented by other features of the invention that have been described.

[0027] In the drawings, the same reference numerals denote elements having the same function.

[0028] Figure 1Schematic cross-sectional view showing a partial view of the battery system 10. The shown partial view of the battery system 10 shows a battery cell 12, which is arranged in the interior space 14 of the battery housing 16 of the battery system 10. The battery cell 12 has a cell housing 18, in which an exhaust opening 20 is provided. A spark arrester 24 is arranged between the exhaust opening 20 and the side sill / side wall (Seitenschweller) 22.

[0029] If a leak or exhaust occurs in the galvanic cells (not shown in detail) of the battery cell 12, the air flow can be dispersed along the exhaust path shown by the arrow in Figure 1 . If the internal pressure in the cell increases due to exhaust, the gas can be discharged through the exhaust opening 20, where the gas flows through the spark arrester 24 before entering the interior space 14 of the battery housing 16 after being discharged. In this way, not only can sparks and / or particles be filtered from the air flow in the spark arrester 24, but also heat exchange can be carried out, which results in the air flow temperature being lower than a predetermined temperature limit when entering the interior space 14.

[0030] Referring to the components shown and described in conjunction with Figure 1 shows and describes Figure 2 shows a motor vehicle 28 having a battery system 10. In Figure 2 a plurality of battery cells 12 are shown, which are arranged in the battery housing 16 of the battery system 10. For the sake of clarity, only the right outer battery cell 12 is provided with a reference numeral. In addition, in Figure 2 the exhaust path 26 is schematically shown by means of arrows. In the case where gas is discharged from one or more of the battery cells 12, the discharged gas can be spread, dispersed or guided along the exhaust path 26 within the battery housing 16 of the battery system 10. In Figure 2 two edge-located and oppositely arranged exhaust openings 20 of the battery housing 16 are shown. A spark arrester 24 can be provided at each exhaust opening 20. The spark arrester 24 can, in the manner described above, on the one hand retain particles and / or sparks from the air flow, and on the other hand can be used as a heat exchanger to reduce the temperature of the air flow below a predetermined temperature limit before the air flow exits the battery housing 16.

[0031] In a battery system, a cell may vent due to a fault condition in the cell. If the gas mixture is flammable, there is a possibility of self-ignition in the ambient air. In principle, according to the "fire triangle (Branddreieck)", for a gas mixture to be able to burn, three main conditions must exist: sufficient fuel (reductant), sufficient oxygen (oxidant), and sufficient ignition energy. Due to gas emissions, hot particles and / or sparks may be ejected from the battery cell, and the particles and / or sparks may be sufficient as ignition energy.

[0032] Part of the concept of the present invention is to separate the ignition source (hot particles and / or sparks) from the gas mixture before the gas mixture mixes with the air oxygen outside the battery. If the gas mixture cannot self-ignite due to its temperature, then according to the fire triangle, since there is no ignition source, ignition can no longer occur.

[0033] The particle / spark blocking device may at least partially include a mesh-like, breathable support. The support has two main functions: it must be able to absorb the kinetic energy of the particles and / or sparks (mechanical deceleration) and must be able to absorb the thermal energy of the particles and / or sparks (thermal barrier). Accordingly, depending on the kinetic and / or thermal properties of the sparks and / or particles, the support material must be mechanically resistant and / or heat-resistant. Ceramic and / or glass-ceramic materials are particularly suitable for this. The support can optionally be woven from glass fibers, and the glass fibers form an ordered fabric and / or at least partially form a disordered non-woven fabric.

[0034] The introduced exhaust scheme includes 4 levels:

[0035] - Exhaust at the cell level,

[0036] - Exhaust at the hybrid cell level (also called dual-cell module or cell group),

[0037] - Exhaust at the battery system level, and

[0038] - Exhaust from the battery system to the surrounding environment.

[0039] Exhaust at the cell level:

[0040] If a fault occurs inside a pouch cell and the fault causes gas to be generated in the cell, then gas may flow out of the battery cell. A cell fault can theoretically occur at any position within the cell winding in the (galvanic) cell. In a pouch cell, this kind of exhaust usually occurs at any part in the area of the weld. Depending on the mechanical support within the cell group in the battery system, pressure can be applied to the cell, and this pressure affects the gas opening of the cell.

[0041] Exhaust at the level of the hybrid cell:

[0042] The exhaust of the pouch cell in the hybrid cell can be carried out along the weld seam. Starting from the side region of the cell, the cell gas can flow all the way in the steel housing of the hybrid cell to the rupture region. After the rupture opening is triggered or opened, the cell gas can flow out of the housing of the hybrid cell in a defined manner.

[0043] Exhaust at the level of the battery system:

[0044] Inside the battery system, the gas flows from the hybrid cell via a support element (such as an I-shaped support) into a gas channel, which can be at least partially made of steel. There can be a material (preferably a fabric made of fiberglass) inside the gas channel, which can absorb the sparks and / or particles that may be generated during the exhaust of the cell. Such a spark blocking device can prevent the possible combustion of the cell gas outside the battery system. The gas space is separated from the electrical structure space in the battery system.

[0045] Exhaust from the battery system to the surroundings:

[0046] The gas channel can have a rupture element on the battery system housing, which is triggered when the pressure of the inflowing cell gas is high enough. After the cell gas flows into the exhaust channel, the cell gas can be redirected and thus flow in the direction of the rupture element. The cell gas can pass through the rupture element to reach the surroundings.

[0047] In summary, the idea is based on preventing ignition energy. To achieve this, the gas temperature cannot be too high so that it will not autoignite during mixing with ambient air despite filtering out the sparks and / or particles. This can be adjusted by selecting the cell chemical composition or also by dissipating heat purposefully before entering the ambient air.

[0048] In summary, the examples described show how a spark blocking device with a heat exchange function can be provided for a high-voltage battery system.

Claims

1. A battery system (10) having a plurality of battery cells (12) arranged in a battery housing (16), wherein, Each battery cell (12) has a cell housing (18) that at least partially encloses the galvanic cell, wherein the cell housing (18) and / or the battery housing (16) has at least one vent opening (20) which is designed to allow air flow to be discharged from the interior space (14) of the cell housing (18) and / or the battery housing (16) along a predetermined exhaust path (26) into the surroundings of the battery cell (12) and / or the battery system (10), wherein a spark arrestment device (24) is arranged along the predetermined exhaust path (26) and is designed to filter out sparks and / or particles from the air flow. It is characterized in that the spark arrestment device (24) is designed to reduce the flow velocity of the air flow compared to the initial velocity and to guide the air flow along the surface of the spark arrestment device (24), so that the air flow flows along the surface for at least a predetermined duration, wherein the duration, the surface, and the reduced flow velocity are coordinated with each other in such a way that heat output energy is extracted from the air flow to cause the temperature value of the air flow when released into the surroundings to drop below a predetermined temperature limit value, wherein the surface has channels that on the one hand increase the surface area and on the other hand also exert a turning or guiding effect on the air flow, wherein the spark arrestment device (24) is at least partially made of a wire weave, wherein the spark arrestment device is designed to perform a heat exchange function in addition to the filtering function. Inside the battery system, gas flows from the hybrid cell through the support element into the gas channel which is at least partially made of steel, the gas space is separated from the electrical structure space in the battery system, there is a material in the gas channel that can absorb the sparks and / or particles generated during the exhaust of the cell, the gas channel has a rupture element on the battery system housing, and when the pressure of the incoming cell gas is high enough, the rupture element is triggered. After the cell gas flows into the exhaust channel, the cell gas is redirected and thus flows towards the rupture element, and the cell gas passes through the rupture element to reach the surroundings.

2. The battery system (10) according to claim 1, characterized in that, The galvanic cell includes an electrolyte having a predetermined chemical composition, wherein the predetermined temperature limit value is determined based on at least one monomer chemical parameter in the chemical composition.

3. The battery system (10) according to any one of the preceding claims, characterized in that, The spark arrestment device (24) at least partially has a sponge structure with open pores, wherein the open pores are designed to allow the air flow to pass through the pores.

4. The battery system (10) according to claim 1 or 2, characterized in that, The spark arrestment device (24) at least partially has a fabric made of a glass fiber-based material and / or a ceramic material.

5. The battery system (10) according to claim 1 or 2, characterized in that, The spark arrestment device (24) at least partially has oriented and / or non-oriented fibers.

6. The battery system (10) according to claim 1 or 2, characterized in that, The spark arrestment device (24) is arranged on the side of the cell housing (18) and / or the battery housing (16) facing away from the environment and / or on the side facing the environment.

7. The battery system (10) according to claim 1 or 2, characterized in that, The vent opening (20) can be closed by a rupture element.

8. The battery system (10) according to claim 7, characterized in that, The rupture element is designed as a rupture membrane or a rupture disc.

9. A motor vehicle (28) having a battery system (10) according to any one of claims 1 to 8.

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