Battery for an electrically powered vehicle

Abstract

The invention relates to a battery (22), in particular a traction battery, for an electrically powered motor vehicle. This battery comprises a battery cell (4) and a sensor (2) for detecting a gas (G) flowing out of the battery cell (4), wherein the sensor (2) has a substrate (6), in particular a plate-shaped substrate, on which a gel structure (8) for absorbing the gas (G) is arranged, and wherein a first structural element (10) of the gel structure (8) is spaced apart, and preferably parallel and / or concentric, to a second structural element (12) of the structure (8).

Description

[0001] The invention relates to a battery, in particular a traction battery, for an electrically powered motor vehicle, wherein the battery comprises a battery cell and a sensor for gas escaping from the battery cell. Furthermore, the invention relates to an electrically powered motor vehicle having such a battery and a method for operating such a battery.

[0002] An electrically powered motor vehicle typically has a traction battery (high-voltage battery, HV battery) that supplies energy to an electric motor to drive the motor vehicle. An electrically powered motor vehicle is understood to mean, in particular, an electric vehicle that stores the energy required for propulsion solely in the traction battery (BEV, battery electric vehicle), an electric vehicle with a range extender (REEV, range extended electric vehicle), a hybrid vehicle (HEV, hybrid electric vehicle), a plug-in hybrid vehicle (PHEV, plug-in hybrid electric vehicle), and / or a fuel cell vehicle (FCEV, fuel cell electric vehicle), which temporarily stores the electrical energy generated by a fuel cell in the traction battery.

[0003] Such a traction battery typically comprises several battery cells, particularly lithium-ion battery cells, for providing electrical energy. For example, the battery cells are combined into (cell) modules, with the battery cells of each module housed in a module housing or module frame where they are electrically connected to one another.

[0004] Each battery cell comprises an electrode assembly, such as an electrode stack, and an electrolyte. Particularly if the electrolyte is liquid, there is a risk that gas will be formed at the electrodes of the electrode assembly due to decomposition reactions of the electrolyte when the battery cell is energized and / or stored at high temperatures and charge levels. High nickel contents in NMC and NCA materials, which are typically used for high energy densities in cathodes, result in increased gassing behavior.

[0005] If such a gas develops, it initially cannot escape from the cell, resulting in an increase in pressure within the battery cell. When the critical internal cell pressure is exceeded, the battery cell eventually vents, allowing the gas to escape from the cell into the battery compartment. There is a risk that this gas could damage other battery cells or other battery components and / or that the gas could enter the passenger compartment. Depending on the concentration and type of gas, this could be harmful to passengers.

[0006] Furthermore, the release of gas from a battery cell can precede a thermal runaway of the battery cell.

[0007] DE 10 2019 219 617 A1 discloses an electrical energy storage device with a closed housing. At least one gas-sensitive sensor component is arranged in the housing, which is designed to respond to a gas in the housing to enable the acquisition of information about a gas concentration in the housing.

[0008] US 2015 / 0303723 A1 discloses the use of a sensor for detecting a gas within a battery cell. The sensor comprises a glass fiber onto which a sol-gel matrix containing an analyte is applied.

[0009] A gas sensor is known from DE 21 2018 000 235 U1. Light is emitted from a light source, and the concentration of a gas is determined based on the intensity of the light received by a detector.

[0010] EP 3 767 735 B1 discloses a sensor device for detecting fire or overheating of lithium-ion battery cells. This device comprises a light source and a photodetector. Light is emitted, which is absorbed by CO2. The sensor detects the intensity of the light and uses this to determine the CO2 concentration.

[0011] CN 212085566 U describes a distribution box that uses a color-changing silica gel moisture absorber.

[0012] A galvanic oxygen sensor is disclosed in CN 116559249 A. To prevent acidic components of the gas from penetrating the electrodes of the gas sensor, a gas-absorbing layer is provided.

[0013] The invention is based on the object of providing a battery for an electrically powered motor vehicle that is as safe as possible. In particular, a gas leak from one of the battery cells should be detectable as reliably as possible.

[0014] This object is achieved according to the invention by a battery having the features of claim 1. Furthermore, this object is achieved according to the invention by a motor vehicle having the features of claim 9 and by a method for operating the battery according to claim 10. Advantageous embodiments and further developments are the subject of the subclaims. The statements made in connection with the battery also apply mutatis mutandis to the method and the motor vehicle, and vice versa.

[0015] The battery is preferably intended and configured as a traction battery for an electrically powered motor vehicle. The battery comprises a (battery) housing, which is expediently sealed in a fluid-tight manner. A battery cell, particularly a lithium-ion battery cell, is arranged within the housing, i.e., in a housing interior. The battery expediently comprises several such battery cells, which are accommodated in the housing. For example, the battery cells are combined in one or more modules, and are accommodated, for example, in a respective module housing separate from the battery housing.

[0016] The battery further comprises a (gas) sensor that detects a gas escaping from the battery cell or from at least one of the battery cells. The sensor is arranged inside the battery so that escaping gas from the battery cell can reach the sensor. For example, the sensor is arranged on the battery cell, in particular on an outer side of its cell housing, if present on the module housing or in the module housing, on an inner side of the battery housing, or in an absorber arranged inside the battery, which is intended to absorb and / or sorb gas escaping from the or one of the battery cells.

[0017] The sensor comprises a substrate, preferably plate-shaped. Its base area preferably has a maximum dimension of between 5 and 50 mm and a wall thickness of between 2 and 5 mm.

[0018] A gel structure, hereinafter also referred to as a gel structure, is arranged on the substrate. The gel structure comprises at least a first and a second structural element, wherein the first structural element is arranged at a distance from the second structural element on a common (base) side of the substrate. Preferably, the first structural element is oriented parallel to the second structural element. Particularly preferably, the first and second structural elements are arranged concentrically with one another.

[0019] In other words, the gel is arranged in spaced-apart regions of the substrate to form the structural elements.

[0020] “Concentric” refers to geometric figures that have the same center of gravity.

[0021] In summary, each of the structural elements is formed from the gel. For example, the first and / or second structural element is plate-shaped or formed along a line, i.e., linear (track-like). For example, the structural elements are formed as mutually concentric rectangles, in particular squares, or preferably as mutually concentric rings, or in the manner of a "bull's-eye," as a circular disk and as a circular ring concentric with it.

[0022] In particular, the gel forms a kind of indicator for the gas, as described below.

[0023] The gel, and thus the gel structure, is designed to absorb and / or adsorb at least a portion of the gas escaping from the battery cell. The gel comprises a (first) component that at least temporarily binds the gas escaping from the battery cell and absorbed and / or adsorbed in the gel. For example, this first component is a cyclic oligosaccharide, in particular a cyclodextrin. Examples of cyclodextrins used include α-(alpha)-cyclodextrin, β-(beta)-cyclodextrin, and γ-(gamma)-cyclodextrin. Furthermore, the component is designed such that it forms a complex, i.e., a coordination compound, with the gas.

[0024] The gel of the respective structural element expands due to the adsorption and / or absorption of the gas. The gel "swells." In other words, the gel increases in volume due to the absorption and binding of the gas. This changes the spatial extent of the respective structural element and / or the distance between the structural elements. As will be explained below, particularly in connection with the method for operating such a battery, such a change in the structure can be detected relatively reliably.

[0025] The gas formed, in particular, during the decomposition of the electrolyte and flowing out of the battery cell includes, for example, carbon dioxide (CO2), carbon monoxide (CO), hydrogen (H2), and / or methane (CH4). Carbon monoxide is typically formed relatively early in the battery cell. For this reason, a gel designed for the absorption and / or adsorption of carbon monoxide is preferably used. Thus, the gel preferably has a (first) component that binds carbon monoxide at least temporarily, in particular forming a coordination bond with it.

[0026] Furthermore, depending on the shape of the first and second structural elements, their thickness, i.e., their extension in a plane parallel to the substrate, is between 100 µm and 5 mm, in particular between 100 µm and 1 mm. In a linear configuration of the first and / or second structural element, its extension perpendicular to the longitudinal direction of the line and parallel to the substrate is preferably between 100 µm and 500 µm, in particular between 100 µm and 250 µm.

[0027] Additionally or alternatively, the preferably constant distance between the first and / or the second structural element is between 50 µm and 1 mm.

[0028] For example, the gel structure is produced and / or applied to the substrate using a photo-ligation process or a printing process.

[0029] According to an expedient embodiment, the gel has at least one (second) component, in particular a chromophore, which causes the gel to change its colour upon absorption and / or adsorption of the gas, in particular carbon monoxide.

[0030] For this purpose, the gel contains, for example, potassium disulfitepalladate (II) (K2Pd(SO3)2) as a component, whereby the potassium disulfitepalladate (II) reacts with carbon monoxide. This forms palladium, which results in a discoloration of the gel. Alternatively or additionally, the sensor is designed as a biomimetic sensor. Such a biomimetic sensor binds the gas, in particular carbon monoxide, in the manner of hemoglobin. In particular, the gas forms a complex, i.e., a coordination compound, with one of the components of the gel. The gel, in the manner of a biomimetic CO detector, contains, for example, a cyclic oligosaccharide, in particular a cyclodextrin, and / or a chromophore and / or at least one metal salt, for example, NaCl, as components. The chromophore causes the gel to change color upon absorption of the gas.

[0031] In summary, the optical density of the gel changes due to the discoloration, thus due to the gas.

[0032] Due to the color change and, additionally, the change in structure due to its expansion upon absorption and / or adsorption of the gas, the visual perception of the gel is facilitated, for example, by a user with the naked eye. This advantageously makes it relatively reliable and / or easy to detect leaked gas using the sensor. Furthermore, it is relatively easy to determine the gas concentration based on the intensity of the color change and the change in structure.

[0033] The gel preferably consists of a cyclodextrin, a chromophore, and a metal salt, or comprises a cyclodextrin, a chromophore, and a metal salt. The absorbed gas, in particular CO, reacts chemically with an active ingredient of the gel, i.e., with the chromophore, such as potassium disulfitopalladate (II). The chromophore is mixed with a component from the group of cyclic oligosaccharides, such as cyclodextrin, and one or more metal salts. In summary, the potassium disulfitopalladate (II) is responsible for the color change of the gel, and the cyclodextrin for the volume change.

[0034] According to a suitable embodiment, the gel comprises electrically conductive particles. For example, the gel comprises graphite, aluminum particles, and / or silver particles. If the respective structural element expands due to the absorption and / or adsorption of the gas, the average spacing of the electrically conductive particles in the gel also increases, so that the electrical resistance of this structural element changes accordingly, in particular, increases.

[0035] In this sensor design, the structural elements are expediently spaced from one another such that they touch due to their expansion during gas absorption / adsorption. In particular, the distance between the structural elements is between 50 µm and 250 µm, especially between 50 µm and 100 µm. Such contact between the structural elements results in a sudden reduction in the electrical resistance of the gel structure.

[0036] The size of the electrically conductive particles can be in the nanometer range, e.g., between 1 nm and 100 nm, and / or in the micrometer range, e.g., 1 to 100 µm.

[0037] The gel expediently also comprises the first component, in particular a cyclic oligosaccharide, preferably a cyclodextrin, so that the volume of the structural elements increases upon absorption of the gas. For example, the gel also comprises a chromophore, such as potassium disulfite palladate (II), and / or a metal salt. Using a chromophore makes it possible to optically detect the gas by measuring its electrical resistance and the color of the gel.

[0038] According to a suitable development, the sensor has a cover, in particular a plate-shaped cover, for the gel. This cover is expediently oriented parallel to the substrate. The cover serves in particular to protect the gel structure, in particular from contact or destruction. The cover is arranged at a distance from the gel, i.e. from the gel structure. The gel is therefore arranged between the substrate and the cover, wherein the cover is spaced from the substrate in such a way that the gel is not in contact with the cover. In other words, the distance between the cover and the substrate is greater than the height of the gel, i.e. the extent of the gel in a direction from the substrate to the cover. In this way, circulation of the gas above the gel is enabled.

[0039] For example, the cover has a wall thickness, i.e. an extension in a direction perpendicular to the substrate, of between 1 mm and 2 mm.

[0040] The substrate and / or the cover are preferably transparent. For example, the substrate and / or the cover are made of glass or plastic.

[0041] According to a suitable embodiment, a spacer element, also referred to as a distance piece, is provided, which is arranged between the substrate and the cover. The spacer element thus keeps the cover spaced apart from the substrate. The spacer element is expediently arranged on the substrate outside the area encompassed by the gel structure. In particular, the spacer element is arranged in the area of ​​the outer periphery of the substrate.

[0042] For example, the spacer element is bonded to the substrate and / or the cover or molded onto the substrate and / or the cover. For example, a two-component material is used for bonding.

[0043] To allow the gas to enter the space between the cover and the substrate and interact with the gel, this space is fluidically connected to the sensor's environment. Thus, the gas can flow from an area outside the sensor into the area of ​​the gel structure and / or flow from this area into the sensor's environment.

[0044] For this purpose, the spacer element is not designed to completely surround the gel structure, for example, but only to surround the gel structure in sections. Additionally or alternatively, the spacer element is designed to be porous, in particular open-pored.

[0045] The height of the spacer element, i.e., its extension in a direction perpendicular to the plane spanned by the substrate, is preferably between 50 µm and 1 mm. The spacer element may be higher than the gel structure.

[0046] According to an advantageous embodiment, the battery comprises a light source. This is provided and designed to output a light signal to the sensor, i.e., to emit light into the sensor. For example, the light source is designed as an LED (light-emitting diode). The battery further comprises a light sensor (light detector) for detecting the light signal from the (gas) sensor. The light sensor is thus designed to detect the light signal emitted by the light source into the sensor after it has passed through the (gas) sensor.

[0047] For example, the light source is arranged on the substrate and the light sensor on the cover, or vice versa. Alternatively, the light source and / or the light sensor are arranged at a distance from the (gas) sensor, with the light signal being guided from the light source to the gas sensor via a light guide, for example, a fiber optic cable, and / or with the light signal being guided from the gas sensor to the light sensor via a light guide.

[0048] The light signal is thus detected by the light sensor after passing through the gas sensor and its gel structure. As it passes through the gel structure, the light signal is absorbed according to a discoloration of the gel and thus according to the gas concentration of the gas, so that the optical power of the detected light signal is reduced. The corresponding measurement signal is output, in particular amplified, to a control unit of the battery for evaluation. This is intended and configured to evaluate the measurement signal, in particular with regard to the optical power of the light signal. A table or characteristic curve is expediently used in a memory of the control unit, which assigns a corresponding gas concentration of the gas to the optical power or electrical resistance.

[0049] According to an advantageous development, the battery comprises a further (gas) sensor for detecting a gas flowing out of a further battery cell. In particular, the further (gas) sensor is designed according to one of the variants of the (gas) sensor described above. The battery comprises a light distribution device, for example in the manner of a demultiplexer, wherein light signals from the light source can be output sequentially to the (gas) sensor and to the further (gas) sensor using the light distribution device. Thus, only one common light source is provided for both (gas) sensors, wherein light signals output by this light source are always only directed to one of the (gas) sensors at a time using the light distribution device.

[0050] The light distribution device therefore has an input to which the light signal from the light source is fed, and an output for each (gas) sensor to output the light signal. For example, the input is connected to the light sensor and / or the outputs are connected to the (gas) sensors via a respective optical fiber.

[0051] The battery expediently includes an additional light distribution device, by means of which the light signals that have passed through the (gas) sensors are routed to the common light sensor. For example, this additional light distribution device is designed in the manner of a multiplexer. The additional light distribution device thus comprises a respective input for each of the (gas) sensors and a common output that is coupled to the light sensor.

[0052] It is therefore advantageous to use only a single light source and a single light detector for all gas sensors.

[0053] During the evaluation of the measurement signal, a temporal segment of the measurement signal is conveniently assigned to the gas sensor to which the light signal was supplied via the light distribution device for the period corresponding to the temporal segment. This allows the gas concentration to be determined at different locations in the battery where the gas sensors are located.

[0054] In summary, it is advantageous for the battery to detect a thermal runaway process and / or the venting of a battery cell relatively reliably and / or relatively early. This also increases safety for the battery user. The gel serves as a kind of indicator for the gas.

[0055] A further aspect of the invention relates to an electrically powered motor vehicle having a battery in one of the variants described above. The battery is expediently a traction battery (high-voltage battery) for supplying a traction drive with electrical energy.

[0056] A further aspect of the invention relates to a method for operating a battery in one of the variants described above. According to the method, the electrical resistance of the gel structure, in particular the electrical resistance of one of its structural elements, is first determined.

[0057] For this purpose, for example, the respective structural element is subjected to an electrical voltage and the current through it is measured.

[0058] Alternatively or additionally, the optical power of a light signal that has passed through the (gas) sensor and thus the gel structure is determined. The light signal is conveniently emitted by the light source and detected by the light sensor.

[0059] The gas concentration is then determined based on the optical power and / or electrical resistance. For this purpose, a table or characteristic curve stored in the control unit's memory is used, which assigns a corresponding gas concentration to the optical power or electrical resistance.

[0060] If a specified limit is exceeded, a warning is issued to the battery user. Alternatively or additionally, emergency ventilation of the battery is initiated, for example, to remove the gas from the battery casing.

[0061] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In the drawings: Fig. 1a schematically shows in plan view a sensor for detecting a gas, the sensor comprising a substrate on which a gel is applied as an indicator for the gas, Fig. 1b schematically shows the sensor in a sectional view according to the section plane E of the Fig. 1a, Fig. 1c schematically shows, on an enlarged scale, the area A of the sensor according to the Fig. 1b, Fig. 2 schematically shows a battery with a sensor according to the Fig. 1a to 1c, wherein a light source is arranged on the substrate and a light sensor is arranged on a cover, Fig. 3 schematically shows an alternative embodiment of the battery, wherein the light source and the light sensor are each connected to the sensor by means of a light guide, Fig. 4 schematically shows a battery of an electrically driven motor vehicle designed as a traction battery, wherein the traction battery has cell modules, each of which has a sensor according to the Fig. 1a to 1c, wherein a single light source can emit light sequentially to one of the sensors by means of a light distribution device, Fig. 5 an alternative embodiment of the sensor, wherein the gel comprises conductive particles, and wherein an electrical resistance of the gel is detected, Fig. 6 schematically shows an alternative embodiment of the traction battery, in which the sensor is arranged in an absorber for absorbing gases flowing out of battery cells, Fig. 7 schematically shows an alternative embodiment of the traction battery, the battery housing of which has a transparent window, wherein the sensor is arranged in the region of the window, and Fig. 8 shows a flowchart of a method for operating a battery having a battery cell and a sensor for detecting a gas escaping from the battery cell.

[0062] Corresponding parts and sizes are always provided with the same reference symbols in all figures.

[0063] In the Fig. 1a to 1c depict a (gas) sensor 2. This sensor serves to detect a gas G and / or its (gas) concentration c, wherein the gas G has escaped from a battery cell 4 (see below), in particular a lithium-ion battery cell. In particular, the gas G is carbon monoxide.

[0064] The sensor 2 comprises a plate-shaped substrate 6, which, according to the exemplary embodiment shown here, has a circular base. However, other shapes for the base are also suitable, for example, a rectangular base for the substrate 6. The diameter d—or, in the case of a rectangular base, the largest side length—of the substrate 6 is between 5 mm and 50 mm, and the thickness w of the substrate 6, i.e., an extension perpendicular to the plane spanned by the substrate 6, is between 2 mm and 5 mm.

[0065] A structure 8 made of a gel, also referred to below as gel structure 8, is arranged on the substrate 6. This is shown in the Fig. 1a to 1c are shown hatched for clarity. The gel structure 8 comprises a first structural element 10, a second structural element 12, a third structural element 14, and a fourth structural element 16, wherein the structural elements 10 to 16 are arranged in the manner of a "bull's eye" according to the exemplary embodiment shown here. Thus, the structural elements 10 to 14 are designed as mutually concentric rings, and the structural element 16 is designed as a circular disk concentric with these rings 10 to 14.

[0066] According to further embodiments not shown in detail, the gel structure 8 is configured differently. For example, its structural elements are concentrically arranged rings or concentrically arranged rectangles. Alternatively, the structural elements are lines oriented parallel to one another.

[0067] At most, the structural elements 10 to 16 are arranged at a distance from one another, at least in sections. In other words, with respect to a direction perpendicular to the vertical direction H, one of the structural elements is spaced from the other structural elements, thus forming a gel-free region B between the structural elements 10 to 16. The distance between the gel structures is between 50 µm and 1 mm, preferably between 50 µm and 250 µm.

[0068] The thickness of the respective structural element 10 to 16 is between 100 µm and 5 mm; when designed as a line or circular ring, its line width b (i.e. the extension perpendicular to the line's longitudinal direction) or its ring thickness b (i.e. radial extension) is between 100 µm and 500 µm, in particular between 100 µm and 250 µm.

[0069] The sensor 2 further comprises a plate-shaped cover 18 for the gel, wherein the cover 18 is arranged parallel to and spaced from the substrate 6. The cover 18 is spaced from the gel in the vertical direction H. The vertical direction H is understood to be the direction oriented perpendicular to the side of the substrate 6 on which the gel is arranged, in other words the direction oriented perpendicular to the plane spanned by the substrate 6. The cover 18 has, for example, a wall thickness, i.e., an extension in the vertical direction H, of between 1 mm and 2 mm.

[0070] Furthermore, the sensor 2 has a spacer element 20 which is arranged between the cover 18 and the substrate 6 and which keeps the cover 18 spaced from the substrate 6.

[0071] According to the embodiment of the sensor according to the Fig. 1a to 1c, the spacer element 20 is arranged in the region of the outer circumference of the substrate 6. Specifically, the spacer element 20 extends along the outer circumference of the side of the substrate 6 on which the gel is arranged. Thus, the spacer element 20 is arranged outside the gel structure 8.

[0072] The spacer element 20 is designed such that the spatial region between the substrate 6 and the cover 18 is fluidically connected to the environment of the sensor 2. For this purpose, the spacer element 20 is designed to be permeable to air, in particular permeable to the gas G. For this purpose, the spacer element 20 is, for example, porous and / or has (in a manner not shown in detail) air channels that connect this spatial region to the environment of the sensor 2.

[0073] The height of the spacer element 20, i.e. its extension in the vertical direction H, is between 50µm and 1mm, but is at most larger than a height of the gel.

[0074] The substrate 6 and the cover 18 are advantageously designed to be optically transparent. For example, the substrate 6 and the cover 18 are made of glass or a transparent plastic.

[0075] The gel adsorbs and / or absorbs the gas G, in particular CO, and thereby changes its color. For example, the gel comprises potassium disulfite palladate (II) as a chromophore, a cyclic oligosaccharide such as cyclodextrin, and / or a metal salt. The gel thus comprises a chromophore as a (coloring) component that reacts with the absorbed gas G, thus causing the gel to change its color.

[0076] In addition, the volume of the respective structural element 10 to 16 increases due to the absorption and / or adsorption of the gas. This change in shape can be perceived and / or detected relatively easily due to the spaced-apart arrangement of the structural elements. In addition to the color change, the shape of the gel structure 8 also changes due to the gas G, with the color change and the shape change being relatively visually perceptible to a user.

[0077] In the Fig. 2 schematically shows a battery 22. This comprises a battery housing 24. In the battery housing 24, a battery cell (not further shown) is arranged, from which the gas G can escape, as well as a sensor 2, which according to the Fig. 1a to 1c. A light source 26, embodied here as an LED, is arranged on the sensor 2, namely on the outer base side 32 of its substrate 6. The light source 26 is provided with electrical energy from an energy source 28.

[0078] Furthermore, the battery 22 includes a light sensor 30, which is arranged on the outer base side 32 of the cover 18. This is designed and configured to detect the light signal emitted by the light source 26 into the sensor 2 after it has passed through the sensor 2. The light sensor 30 is connected to a control unit 34 of the battery 22 for signal and / or data transmission purposes.

[0079] In summary, the (gas) sensor 2 is arranged between the light source 26 and the light sensor 30.

[0080] According to the alternative embodiment of the battery 22 according to the Fig. 3 is in contrast to the design of the Fig. 2, the light source 26 and the light sensor are arranged at a distance from the (gas) sensor 2. The light signal L emitted by the light source 26 is guided to the sensor 2, in particular to the substrate 6, via a light guide 36. The light signal L', which has passed through the sensor 2, is also guided to the light sensor 30 via another light guide 36.

[0081] According to an alternative embodiment of the battery 22 according to the Fig. 4 comprises these cell modules 38, three of which are shown as examples. Each of the cell modules 38 is assigned a sensor (gas) sensor 2 according to the Fig. 1a to 1c. According to the example shown here, the gas sensors 2 are arranged on an outer side of the housings 40 of the cell modules 38. According to an alternative not shown further, the sensors 2 are arranged within the housing 40 of the respective cell module 38.

[0082] According to a further alternative, not shown in detail, the sensors 2 are arranged on the battery cells 4, in particular on their cell housings, and in this case, for example and if present, within the housing 40 of the respective cell module 38.

[0083] The battery 22 further comprises a control unit 34, for example a so-called battery management system (BMS), which controls the (single) light source 26 and is connected to the (single) light sensor 30 for signal and / or data transmission. For example, the light sensor 30 and the light source 26 are part of the control unit 34; according to a variant not shown in detail, these can also be structurally separate from the control unit 34, wherein the control unit 34 is connected to the light source 26 and the light sensor 30 for signal and / or data transmission.

[0084] Furthermore, the battery 22 comprises a light guide 36, for example a fiber optic cable, which is provided and arranged such that a light signal L emitted by the light source 26 is guided to a light distribution device 42. The light distribution device 42 serves to output the light signal L emitted by the light source 26 to the sensors 2, i.e., to distribute it, in such a way that a light signal L is or is supplied to only one of the sensors 2 at a time. In other words, these light signals L are supplied to the sensors 2 in chronological succession, i.e., one after the other. From the light distribution device 42, the light signals L can be guided to the respective (gas) sensor 2 via further light guides 36.

[0085] The light signals L' that have passed through the gas sensors 2 can be transmitted to a further light distribution device 42 via additional optical fibers 36. This device serves to output the light signals L' from all (gas) sensors 2 into a common optical fiber 36, which then transmits these light signals L' to the light sensor 30.

[0086] In the Fig. 5 shows an alternative embodiment of the (gas) sensor 2. In contrast to the embodiment of the sensor 2 according to Fig. 1a to 1c, the gel of the gel structure 8 additionally comprises electrically conductive particles such as graphite, aluminum particles, and / or silver particles.

[0087] In this embodiment of the sensor 2, the structural elements 10 to 16 are spaced apart from one another such that they touch each other due to their expansion during the absorption / adsorption of the gas G. For this purpose, the distance between the structural elements is preferably between 50 µm and 250 µm, in particular between 50 µm and 100 µm.

[0088] One of the structural elements 10 is connected to a voltage source 44 so that the electrical resistance of this structural element 10 can be determined based on a current measurement. If the respective structural element 10 expands due to the absorption and / or adsorption of the gas, the average distance between the electrical particles in this structural element also increases, so that the electrical resistance of this structural element 10 changes accordingly, in particular increases. In addition, the detected current increases abruptly, and the determined resistance therefore decreases, as soon as the structural element 10 comes into contact with another structural element. A characteristic curve or a table is expediently stored in a memory (not shown in detail) of the control unit 34, on the basis of which a concentration of the gas G is assigned to the detected current or, analogously, to the electrical resistance of the structural element determined therefrom.

[0089] According to a variant not further illustrated, one of the structural elements is connected to one pole of the voltage source 44, and one of the other structural elements is connected to the other pole of the voltage source 44. The detected current increases abruptly as soon as the structural elements touch due to their expansion. Such contact only occurs at a correspondingly high concentration of the gas G, so that, for example, by comparing the threshold value for the detected current, it is relatively easy to determine whether a corresponding gas concentration c has been reached.

[0090] In the Fig. Figure 6 shows a further embodiment of the battery 22. At least one gas sensor 2, here two gas sensors 2, are arranged in an absorber 46 of the battery 22. Such an absorber 46 is intended to absorb the gas G escaping from a battery cell 4 and to retain it there at least temporarily, in particular to bind it. The absorber 46 is expediently accommodated in the battery housing 24.

[0091] The gas sensor(s) 2 can be configured according to one of the variants of Fig. 1a to 1c or according to the Fig. 5. For example, an evaluation is carried out based on the evaluation of the optical power detected by the light sensor 30 or based on the determined electrical resistance of the gel structure 8, in particular one of its structural elements. Alternatively, a transparent window 50 is provided in an outer wall 48 of the absorber 46 and in the battery housing 24, through which the sensor 2 can be viewed by a user of the battery 22. An absorption material for the gas G arranged in the absorber 46, i.e. in the space enclosed by the outer wall 48, is in the Fig. 5 not further shown.

[0092] In the Fig. Figure 7 shows a further embodiment of the battery 22. Here, the battery housing 24 includes a window 50, with the sensor 2 being arranged within the battery housing 24 such that it can be viewed by a user from outside the battery housing 24. In particular, the sensor 2 is arranged directly at the window 50.

[0093] In a manner not shown in detail, an electrically powered motor vehicle has a battery in one of the variants described above. In particular, battery 22 forms the traction battery of the motor vehicle.

[0094] In the Fig. Figure 8 shows a flow diagram representing the operation of a battery 22 comprising a battery cell 4 and a sensor 2 in one of the variants shown above.

[0095] In a first step I, according to the explanations for Fig.5 the electrical resistance R of the gel structure 8 or at least one of its structural elements 10 to 16 is determined.

[0096] In an embodiment of the battery 22 with a light source 30 and a light sensor 26, the optical power P of the light signal L' is additionally or alternatively determined which was emitted by the light source 26 into the sensor 2, passed through it and detected by the light sensor 30.

[0097] Subsequently, in a second step II, a gas concentration c of the gas G is determined based on the optical power P and / or the electrical resistance R. In particular, a gas concentration c of the gas G is assigned to the optical power P or the electrical resistance R. For this purpose, a characteristic curve, table, or function stored in a memory of the control unit is used.

[0098] Steps I and II are performed repeatedly, for example, every 100 milliseconds, every second, or every minute, so that a current gas concentration c is recorded. In other words, an "online" determination of the gas concentration c of the gas G is performed.

[0099] Depending on the determined gas concentration c and / or its temporal progression, different measures are carried out using the control unit 34 of the battery 22.

[0100] If, for example, a gas concentration c is detected which is below a predetermined gas concentration threshold value S1 and / or does not exceed this threshold value S1 for longer than a predetermined period of time t1, the battery 22 continues to operate normally (step IIIa).

[0101] Alternatively, if the gas concentration c increases by more than a predetermined Δc value within a predetermined period t2, emergency ventilation of the battery 22 is initiated. In this process, the air (including the gas G) in the battery housing 24 is guided out of the battery housing 24 to the outside of the battery. In particular, the air in the battery housing 24 is sucked out or blown out (step IIIb).

[0102] Alternatively, the cell pack or cell module associated with the sensor 2 is deactivated, in particular switched off, if the detected gas concentration c is greater than a predetermined gas concentration threshold value S2, which is, for example, equal to the gas concentration threshold value S1, for more than a predetermined time period t3, which is, for example, equal to the time period t1 (step IIIc).

[0103] In all three variants according to steps IIIa, IIIb, or IIIc, for example, information is output to a battery user regarding the gas concentration c and / or, in steps IIIb and IIIc, a hazard warning is output. Additionally or alternatively, the detected gas concentration c and / or its temporal progression are stored in a memory of the control device 34 so that they can be evaluated, for example, during maintenance or repair.

[0104] The invention is not limited to the exemplary embodiments described above. Rather, other variants of the invention can be derived from them by those skilled in the art within the scope of the claims without departing from the subject matter of the invention. In particular, all individual features described in connection with the exemplary embodiments and / or in the claims can also be combined with one another in other ways without departing from the subject matter of the invention. List of reference symbols 2 (gas) sensor 4 battery cells 6 Substrat 8 Gel structure / structure made of gel 10 first structural element 12 second structural element 14 third structural element 16 fourth structural element 18 Cover 20 spacer element 22 Battery 24 battery housings 26 Light source 28 Energy source 30 light sensor 32 outer base side 34 Control unit 36 light guides 38 cell module 40 Cell module housing / cell module housing 42 Light distribution device 44 Voltage source 46 absorbers 48 exterior wall 50 windows b Ring thickness of the structural element c Gas concentration Δc value d diameter t1 to t3 duration w thickness A area B gel-free area G Gas E cutting plane H Vertical direction L, L' light signal P optical power R electrical resistance S1,S2 threshold I Determination of optical power and / or electrical resistance II Determination of gas concentration IIIa Normal operation IIIb Emergency ventilation IIIc Deactivation of the cell module or cell pack

Claims

[1] Battery (22), in particular traction battery, for an electrically driven motor vehicle, comprising - a battery cell (4), and - a sensor (2) for detecting a gas (G) escaping from the battery cell (4), - wherein the sensor (2) comprises a, in particular plate-shaped, substrate (6), on which a structure (8) made of gel for absorbing the gas (G) is arranged, and wherein a first structural element (10) of the gel structure (8) is arranged at a distance, and preferably parallel and / or concentrically, to a second structural element (12) of the gel structure (8), and - wherein a thickness (d) of the first and second structural elements (10, 12) is each between 100 µm and 5 mm. [2] Battery (22) according to claim 1, characterized by that the sensor (2) has a, in particular plate-shaped, cover (18) for the gel, wherein the cover (18) is arranged at a distance from the gel. [3] Battery (22) according to claim 2, characterized by that a spacer element (20) is arranged between the substrate (6) and the cover (18), wherein the space between the substrate (6) and the cover (18) is fluidically connected to the environment of the sensor (2). [4] Battery (22) according to one of claims 1 to 3, characterized by that the gel has a component that causes the gel to change color upon absorption of the gas (G). [5] Battery (22) according to one of claims 1 to 4, characterized by a light source (26) for outputting a light signal (L) into the sensor (2) and by a light sensor (30) for detecting the light signal (L') from the sensor (2). [6] Battery (22) according to claim 5, characterized bya further sensor (2) for detecting a gas (G) flowing out of a further battery cell (4), wherein the light signal (L) from the light source (26) can be output sequentially to the sensor (2) and to the further sensor (2) by means of a light distribution device (42). [7] Battery (22) according to one of claims 1 to 6, characterized by that the distance between the first and / or the second structural element (10,12) is between 50 µm and 1 mm. [8] Battery (22) according to one of claims 1 to 7, characterized by that the gel contains electrically conductive particles. [9] Electrically driven motor vehicle with a battery (22) according to one of claims 1 to 8. [10] Method for operating a battery (22) according to one of claims 5 to 8, - wherein the electrical resistance (R) of the gel structure (8) or one of its structural elements (10, 12, 14, 16) is determined, and / or - wherein the optical power (P) of a light signal (L') which has passed through the sensor (2) is determined, and - wherein a gas concentration of the gas (G) is determined based on the optical power (P) and / or the electrical resistance (R).

Images