Sensor arrangement, battery module and method for detecting at least one gas component of a gas escaping from a thermally through battery cell

Abstract

The invention relates to a sensor arrangement (10) with a sensor element (30) for a gas sensor (32), wherein the sensor element (30) comprises an electrically conductive sensor layer (28) comprising at least one material component (M) designed to react with at least one gas component (34) of a gas (36) that escapes from a battery cell (38) in the event of thermal runaway. The sensor arrangement (10) comprises a flexible printed circuit board (12) comprising an electrically insulating flexible carrier (18), an electrically insulating flexible cover layer (20) having an outer surface (26) facing the environment (24), and at least one first electrical conductor (22) arranged between the carrier (18) and the cover layer (20), wherein the sensor layer (28) is arranged on the outer surface (26) of the cover layer (20).

Description

[0001] The invention relates to a sensor arrangement with a sensor element for a gas sensor, wherein the sensor element comprises an electrically conductive sensor layer comprising at least one material component designed to react with at least one gas component of a gas that escapes from a battery cell in the event of thermal runaway. The invention further relates to a battery module and a method for detecting at least one gas component of a gas.

[0002] Gas sensors can be used in batteries, for example, high-voltage batteries for motor vehicles. If a battery cell in such a battery experiences thermal runaway, it typically releases gases. These gases can be detected by such a gas sensor, and / or their concentration or changes in concentration can be detected within the battery casing. However, integrating such a gas sensor into a battery requires considerable installation space, incurs additional costs, and also necessitates complex wiring.

[0003] WO 2018 / 112486 A1 describes a sensor arrangement for determining and measuring the concentration of several gases. The sensor arrangement comprises a sensor structure with conductive elements arranged in a matrix and a plurality of contacts connected to the conductive elements. The conductive elements are formed with different metals and / or metal oxides to measure more than two gases in a gas mixture in isolation from each other. The matrix may consist of metal films or metal oxide films. The conductive elements arranged in the matrix may be at least partially made of tin oxide and / or zinc oxide, the tin oxide and / or zinc oxide being n-doped.

[0004] WO 2011 / 066984 A1 describes a chemical media sensor for gases and / or liquids, which can be used as a semiconductor gas sensor for the detection of nitrogen oxides, ammonia, hydrocarbons, oxygen and / or for exhaust aftertreatment in internal combustion engines.

[0005] The object of the present invention is to provide a sensor arrangement for a battery, a battery module and a method that allows for the simplest and most cost-effective design as well as the simplest, most space-saving and most cost-effective integration of a sensor element for a gas sensor into a battery.

[0006] This problem is solved by a sensor arrangement, a battery module, and a method with the features according to the respective independent claims. Advantageous embodiments of the invention are the subject of the dependent claims, the description, and the figures.

[0007] A sensor arrangement according to the invention comprises a sensor element for a gas sensor, wherein the sensor element comprises an electrically conductive sensor layer comprising at least one material component designed to react with at least one gas component of a gas that escapes from a battery cell in the event of thermal runaway. The sensor arrangement comprises a flexible printed circuit board comprising an electrically insulating, flexible substrate and an electrically insulating, flexible cover layer having an outer surface facing the environment, and comprising at least one first electrical conductor arranged between the substrate and the cover layer, wherein the sensor layer is arranged on the outer surface of the cover layer.

[0008] The invention is based on the finding that a flexible printed circuit board (FPC) can be used, for example, to connect various sensors to a battery module or its battery cells. Such a flexible printed circuit board can carry corresponding sensor leads from the cells or the sensors coupled to them to a control unit. A power supply for the respective sensor is also provided via such a flexible printed circuit board to enable the acquisition of sensor parameters. Furthermore, the invention is based on the finding that such a flexible printed circuit board can simultaneously be used as a substrate for the sensor element of the gas sensor by providing the sensor layer on the outer surface of the cover layer of such a flexible printed circuit board.This allows an existing component, namely the flexible printed circuit board (PCB), to be advantageously used as a substrate for the sensor layer. Simultaneously, it is also possible to supply power to the sensor layer via the flexible PCB, eliminating the need for separate wiring or similar components. This enables a particularly space-saving design of the sensor element for the gas sensor and its integration into an existing component, resulting in significant savings in installation space, costs, and weight. Since such a flexible PCB is typically connected to a control unit anyway for sensing various other sensor parameters, this design is particularly advantageous.This control device can also be used simultaneously to detect at least one gas component and / or an increased concentration of it by means of the sensor layer and accordingly to detect thermal runaway of the battery cell.

[0009] The cover layer and / or substrate of the flexible printed circuit board can, for example, be provided as a film. Furthermore, the cover layer and / or substrate can be made of or comprise a plastic, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polyimide (PI). Other plastics are also conceivable.

[0010] The first electrical conductor can be provided, for example, in the form of a wire or, preferably, in the form of a conductive trace, such as a printed conductor. This can, for example, be printed onto the flexible substrate. Furthermore, additional multi-cell electrical conductors can be provided between the substrate and the top layer. These can also be wires and / or conductive traces. Optionally, further electrical and / or electronic components or modules, in particular surface-mount devices (SMDs), can be arranged on the outer surface of the top layer. These can be part of additional sensors, such as temperature sensors, current sensors, voltage sensors, or the like.

[0011] According to a further advantageous embodiment of the invention, the sensor layer is connected to the at least one first electrical conductor, wherein the sensor layer can be supplied with an electric current and / or an electric voltage via the at least one first electrical conductor. This is based on the knowledge that a reaction, in particular a chemical reaction, between the at least one material component and the gas component leads to a change in the electrical resistance of the sensor layer. This change in resistance can advantageously be used to detect the gas component or a predetermined excessively high concentration of this gas component. For this purpose, the sensor layer can simply be supplied with a current or a voltage. This can be done via the at least one first electrical conductor provided between the substrate and the cover layer.The sensor layer can be coupled to or connected to multiple electrical conductors, for example, two electrical conductors. The sensor layer is therefore preferably connected to at least one such primary electrical conductor via at least two different connection points. The two connection points of the sensor layer are spaced apart and can, for example, be located at opposite ends of the sensor layer. This allows the electrical resistance of the sensor layer, and in particular any change in resistance, to be measured with high accuracy when current is applied to it. The current or voltage that can be supplied to the sensor layer via the electrical conductor can, for example, be provided by a control device connected to the flexible circuit board or its electrical conductors.

[0012] According to a further advantageous embodiment of the invention, at least one through-opening is arranged in the cover layer, which is preferably designed as a cover film, wherein the sensor layer is connected via an electrical connecting element to the at least one first electrical conductor through the at least one through-opening. Thus, the sensor layer can advantageously be contacted to at least one first electrical conductor via such a through-opening, which can preferably be designed as a hole in the cover layer. This can also be referred to as bonding. For example, a wire or strand, or an electrical conductor of another type, can be used as the connecting element.

[0013] Furthermore, it is advantageous if such a through-opening is located near the sensor layer. For example, the through-opening can have a maximum distance to the sensor layer of a few centimeters or millimeters, particularly less than five centimeters, for example, less than one centimeter. This allows the length of the electrical connecting elements to be kept short. The at least one through-opening can also be arranged adjacent to the sensor layer in the cover layer. In addition, several through-openings can be provided. The sensor layer can then be connected via several electrically conductive connecting elements through the respective through-openings to the at least one first electrical conductor and / or to several different first electrical conductors.

[0014] According to a further advantageous embodiment of the invention, the at least one material component is designed to react with ammonia as the at least one gas component. This allows for particularly reliable detection of gas escaping from a battery cell, since ammonia, for example, is significantly easier to detect than hydrogen and / or CO2.

[0015] Nevertheless, the sensor layer or its material component can also be designed in such a way that other gas components, such as hydrogen and / or CO2, can be detected via a corresponding chemical reaction with at least one material component.

[0016] According to a further advantageous embodiment of the invention, at least one material component is zinc oxide. Zinc oxide reacts particularly strongly with ammonia. Therefore, zinc oxide makes it especially easy and reliable to detect ammonia. Furthermore, ammonia is normally absent or present in very low concentrations in the air inside a battery, i.e., when no battery cell is experiencing thermal runaway. This simplifies the detection of thermal runaway in a battery cell, since in such a case the significantly increased ammonia concentration inside the battery can then be easily and reliably detected through the chemical reaction with the zinc oxide.

[0017] The sensor layer can comprise not only at least one material component but also other material components. In particular, the zinc oxide component can also be doped. This can increase the conductivity of the sensor layer. However, the sensor layer can also consist solely of zinc oxide, especially doped zinc oxide, or be composed essentially only of zinc oxide. A high zinc oxide content simplifies detection, especially of ammonia, which in turn allows the sensor layer itself to be made smaller.

[0018] The sensor layer can generally have a thickness that is smaller than the other dimensions of the sensor layer perpendicular to its thickness. For example, the sensor layer can have a maximum dimension perpendicular to its thickness that is at most a few centimeters, for example, a maximum of five centimeters, particularly in the range between two and three centimeters.

[0019] Furthermore, it is also possible for several such sensor layers to be arranged on the flexible printed circuit board, more precisely on the outer surface of the cover layer. The sensor arrangement can also comprise several flexible printed circuit boards, each with at least one or more sensor layers on its outer surface provided by the respective cover layers. It is also possible for only some of the flexible printed circuit boards in a battery to have such sensor layers. This allows for reliable detection of the gas components of the gas escaping from a battery cell, even in a very large battery.

[0020] According to a further advantageous embodiment of the invention, the flexible printed circuit board comprises several secondary electrical conductors, e.g., conductor tracks, arranged between the substrate and the cover layer, and connected to a respective sensor, in particular a temperature sensor and / or voltage sensor and / or current sensor. The flexible printed circuit board is thus not only used to carry the first electrical conductor for the current and / or voltage supply of the sensor layer, but can also be used simultaneously to carry various (other) sensor conductors and, in particular, to provide such sensors themselves. Furthermore, the at least one first electrical conductor to which the sensor layer is connected is preferably an electrical conductor specifically provided for this sensor layer. This electrical conductor should therefore not be coupled to or connected to any other sensor.This allows for particularly reliable measurement results and avoids interactions with other sensors.

[0021] According to a further advantageous embodiment of the invention, the sensor arrangement comprises a control unit connected to the at least one electrical conductor and designed to detect a value of electrical resistance and / or a change in the electrical resistance of the sensor layer, particularly repeatedly, and, depending on the detected value and / or the repeatedly detected value, to detect the gas component and / or thermal runaway of a battery cell. The control unit can also be designed, as already described above, to supply a voltage and / or a corresponding electrical current to the sensor layer via the at least one electrical conductor. During operation of the sensor layer, or during the execution of a measurement to detect the value of the electrical resistance and / or the change in resistance, the control unit thus applies, for example,The sensor requires at least one electrical conductor carrying a current and / or voltage, causing a current to flow through the sensor layer. For example, the control unit can apply a voltage to the first electrical charge and measure the resulting current. Knowing the voltage and current, the electrical resistance can be determined. The control unit can perform such a measurement repeatedly and detect when the electrical resistance changes significantly over time, according to a predefined threshold. This significant change can be detected based on a predefined threshold value, which can be stored in the control unit's memory.If this threshold is exceeded or fallen below by the detected value, the control unit can detect the thermal runaway of a battery cell or detect the presence of the gas component or a certain minimum concentration of this gas component.

[0022] Depending on the detection of the gas component, the control unit can trigger a signal, e.g. to initiate a specific action.

[0023] Furthermore, the invention also relates to a battery module with a sensor arrangement according to the invention or one of its embodiments.

[0024] According to a further advantageous embodiment of the invention, the battery module comprises at least one battery cell to which the flexible circuit board is arranged. In particular, the battery module can also comprise several such battery cells. The battery cells can, for example, be lithium-ion cells. Each battery cell can, for example, have an exposed gas vent through which the respective battery cell can vent in the event of thermal runaway. The flexible circuit board can be arranged on a top or bottom surface, or laterally, of the battery module. In particular, the flexible circuit board can extend in a longitudinal direction that corresponds to a stacking direction of a cell stack with several battery cells arranged side by side in the stacking direction. Such a cell module controller can be arranged at one end of the battery module with respect to the stacking direction.

[0025] The control unit mentioned above could, for example, be a CMC, that is, a cell module controller. One or more such cell module controllers can be assigned to a single battery module.

[0026] The control unit of the sensor array can include a data processing device or a processor circuit. The processor circuit can include at least one microprocessor and / or at least one microcontroller and / or at least one FPGA (Field Programmable Gate Array) and / or at least one DSP (Digital Signal Processor). In particular, the microprocessor can be a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an NPU (Neural Processing Unit). Furthermore, the processor circuit can contain program code. The program code can be stored in a data memory of the processor circuit. The processor circuit can be based, for example, on at least one circuit board and / or on at least one SoC (System on Chip).

[0027] Furthermore, the invention also relates to a battery with a battery module according to the invention or one of its embodiments.

[0028] The battery can, for example, be designed as a high-voltage battery. Furthermore, the battery can also comprise several battery modules according to the invention or several battery modules according to exemplary embodiments of the invention. The battery can, for example, be a traction battery for a motor vehicle.

[0029] The battery may also have a battery housing in which the battery module is located. The battery housing thus encloses an interior space in which the battery module is positioned. The flexible circuit board, including the sensor layer on it, is therefore also located within the interior of the battery housing.

[0030] Furthermore, the invention also relates to a motor vehicle with a battery module according to the invention or one of its embodiments and / or with a battery according to the invention or one of its embodiments.

[0031] The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle. The motor vehicle can be designed as an electric vehicle.

[0032] Furthermore, the invention relates to a method for detecting at least one gas component of a gas that escapes from a battery cell in the event of thermal runaway, wherein a sensor element is provided with an electrically conductive sensor layer comprising at least one material component that reacts, in particular chemically reacts, with the at least one gas component upon contact. A flexible printed circuit board is provided, comprising an electrically insulating flexible substrate and an electrically insulating flexible cover layer having an outer surface facing the environment, and wherein the flexible printed circuit board comprises at least one first electrical conductor arranged between the substrate and the cover layer, the sensor layer being arranged on the outer surface of the cover layer, and wherein a reaction of the at least one material component of the sensor layer with the gas component is detected.

[0033] The advantages described for the sensor arrangement and its embodiments according to the invention apply equally to the method according to the invention.

[0034] The invention also includes further developments of the method according to the invention, which have features already described in connection with the arrangements according to the invention, and vice versa. For this reason, the corresponding further developments of the method according to the invention are not described again here.

[0035] The invention also includes combinations of the features of the described embodiments. The invention therefore also includes realizations that each exhibit a combination of the features of several of the described embodiments, provided that the embodiments have not been described as mutually exclusive.

[0036] The following are exemplary embodiments of the invention described. This is illustrated by: Fig. 1 a schematic representation of a sensor arrangement according to an embodiment of the invention; and Fig. 2 a schematic representation of a battery with a sensor arrangement according to an embodiment of the invention.

[0037] The exemplary embodiments described below are preferred embodiments of the invention. In these exemplary embodiments, the described components each represent individual features of the invention, which can be considered independently of one another and each further develops the invention independently. Therefore, the disclosure is intended to include combinations of features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0038] In the figures, identical reference symbols denote functionally equivalent elements.

[0039] Fig. Figure 1 shows a schematic representation of a sensor arrangement 10 according to an embodiment of the invention. The sensor arrangement 10 comprises a flexible printed circuit board 12, which is shown here in a schematic top view. Fig. Figure 2 shows a schematic cross-sectional view of the sensor arrangement 10, which is arranged on a battery module 14 of a battery 16 or on cells 38 of such a battery module 14.

[0040] The flexible printed circuit board 12 includes a flexible carrier 18 (see below). Fig. 2) and a flexible cover layer 20. The carrier 18 and the cover layer 20 are made of an electrically insulating material. The carrier 18 and the cover layer 20 can, for example, be provided in the form of plastic films or similar materials. Conductive tracks can be placed between the carrier 18 and the cover layer 20, as shown here by way of example in Fig. 2 a first conductor track 22, is arranged. The cover layer 20 has an outer surface 26 facing away from the support 18 and towards an environment 24. On this outer surface 26, an electrically conductive sensor layer 28 is arranged as part of a sensor element 30 of a gas sensor 32. The sensor layer 28 comprises at least one material component M, preferably zinc oxide M, which is designed to interact with at least one gas component 34, in particular ammonia 34, of a gas 36 (cf. Fig. 2) to react chemically, which in the event of thermal runaway of a battery cell 38 (see Fig. 2) escapes from it. Such gas escaping from battery cell 38 is in Fig. 2 schematically illustrated by corresponding arrows 36.

[0041] The top layer 20 can also have through-holes 40 in the form of holes for bonding. The sensor layer 28 can be connected to the flexible printed circuit board 12 via these through-holes 40 and at least one electrical conductor 22, for example via suitable electrically conductive connecting elements 42 (see figure). Fig. 2) Furthermore, the sensor arrangement 10 can include a control device 44 which is connected to the flexible printed circuit board 12. In particular, this can be connected to the at least one electrical line 22. Furthermore, the control device 44 can be designed to apply a voltage to the line 22 and to detect a corresponding current flow through the sensor element, in particular the sensor layer 28, and thereby to measure an electrical resistance R (see Figure 1). Fig. 2) to detect the resistance of the sensor layer 28. This resistance R can be detected repeatedly or continuously, as can any change in resistance resulting from contact between the sensor layer 28 and ammonia 34. If such a change in resistance is detected by the control unit 44, it thereby detects the gas component 34, in particular ammonia 34, and accordingly the thermal runaway T of one of the battery cells 38. Depending on the detection of such a thermal runaway T, the control unit 44 can output a corresponding signal, for example to a higher-level control unit to initiate a specific action.

[0042] Fig. Figure 2 shows a schematic representation of a battery 16 with a battery module 14 or its cells 38 in a side view, on which a sensor arrangement 10, shown in a schematic cross-sectional view, is arranged according to an embodiment of the invention. The sensor arrangement 10 can be arranged as shown in Figure 2. Fig. 1 already described as having been trained.

[0043] The battery cells 38 of the battery module 14 can each include a releasable cell vent 50, e.g., a rupture membrane or a pressure relief valve, through which gas 36 can escape from the respective battery cell 38 in the event of thermal runaway. When such a battery or battery cell 38 begins to gas, several gases 36 are released, including ammonia 34. The FPC 12, i.e., the flexible printed circuit board 12, can include further sensors, which are not shown here. These can generally be attached using an SMD process. The corresponding sensor leads can also run between the carrier 18 and the cover layer 20. In this case, as already described, the sensor, in particular the sensor layer 28, for ammonia determination is attached to the cover film 20, which can be made of PI, PEN, and / or PET.For manufacturing, a thin layer of tin oxide M can be applied to the cover film 20, for example, to its upper surface 26, i.e., the outer surface 26. Holes 40 are provided in the cover film 20 at the edge of this tin oxide layer 28, or more generally, the sensor layer 28, so that direct current from the FPC 12 can be applied to the tin oxide M, and in particular to the sensor layer 28, by means of bonding. The tin oxide M changes its resistance R when it comes into contact with the ammonia 34. The monitoring provided by the control unit 44 can therefore be permanently active and requires no additional energy because it is simply integrated.It is also sufficient to provide the ammonia measurement on a single FPC 12 of such a battery 16, wherein such a battery 16 can generally comprise several battery modules 14 with respective flexible printed circuit boards 12 for the sensory monitoring of the respective battery cells 38 of the module 14 in question. On these several flexible printed circuit boards 12 comprised by the battery 16, a total of, for example, only two or three such sensor layers 28 for gas detection may be provided. These are then preferably arranged centrally with respect to the battery cell arrangement or the overall arrangement of the battery cells 38 comprised by the battery 16, since a gas leak 36 can be detected most reliably in this position.

[0044] Above all, the advantages can be exploited through bonding, i.e., the contacting of the sensor layer 28 to the electrical conductor(s) 22 through the holes 40, so that with an existing FPC 12 current can be sent across the tin oxide surface 28 without additional power supply and ammonia 34 can be detected when the resistance R increases.

[0045] Overall, the examples demonstrate how the invention enables the integration of ammonia detection into the FPC. In particular, it allows for the integration of ammonia measurement into the FPC via a preferably tin oxide layer with direct power supply via the FPC. This has the advantage that no additional thermal runaway sensors are required, thus saving costs, installation space, and wiring effort. The sensor arrangement allows the gas sensor to be provided as an integrated component, especially as a component integrated into the FPC, and also enables a long service life. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2018 / 112486 A1

[0003] WO 2011 / 066984 A1

[0004]

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