Battery and methods for operating a battery

Abstract

The invention relates to a battery (2). This battery comprises a battery cell (4) with an electrolyte (14) comprising a polymerizable solvent (16), wherein the battery cell (4) has nanobubbles (18) within its cell interior, each of which has a shell (20) and a substance (22) contained therein for polymerizing the solvent (16). Furthermore, the battery (2) comprises a sensor (28) for detecting a state variable (S) of the battery cell (4) and an ultrasonic generator (32) for generating ultrasound in the battery cell (4), wherein the ultrasonic generator (32) is controlled and / or is controlled such that, depending on the state variable (S) of the battery cell (4), in particular upon detection of a state variable (S) representing a critical state of the battery cell (4), ultrasonic waves are generated in the battery cell (4) for the release of the substance (22) for polymerizing the solvent (16) due to cavitation.Furthermore, the invention relates to a method for operating a battery (2) and a motor vehicle with such a battery (2).

Description

[0001] The invention relates to a battery with a battery cell, in particular configured as a lithium-ion battery cell, wherein the battery cell comprises an electrolyte with a polymerizable solvent. The invention further relates to a method for operating such a battery cell.

[0002] An electrically powered vehicle typically has a traction battery (high-voltage, HV battery) that supplies energy to an electric motor to propel the vehicle. The term "electrically powered vehicle" refers in particular to 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, especially lithium-ion battery cells, to provide electrical energy. For example, the battery cells are grouped into (cell) modules, with the battery cells of each module housed in a module casing or module frame and electrically connected to each other there.

[0004] Each lithium-ion battery cell has at least one anode and one cathode, between which a separator is arranged. The battery cell also contains an electrolyte for ion transport between the anode and the cathode. This electrolyte preferably comprises a conducting salt and an organic solvent in which the conducting salt is dissolved.

[0005] A thermal runaway of such a battery cell, and thermal propagation (the spread of such a thermal event to another cell in the battery), pose a danger to a user of the battery and / or can result in further damage to the vehicle containing the battery. For example, the affected battery cell may rupture, releasing hot and / or toxic liquids and / or gases.

[0006] Such a thermal event can be detected, for example, by measuring the temperature or pressure within the respective battery cell.

[0007] For example, German patent application DE 10 2020 200 011 A1 discloses a warning system for an electrical energy storage device of a motor vehicle. This system comprises a battery management system that has at least one first sensor for detecting a critical state of the energy storage device and at least one first evaluation unit for issuing a warning message based on data acquired by the first sensor. Furthermore, the warning system comprises a monitoring system independent of the battery management system, which has at least one second sensor for detecting a critical state of the energy storage device and at least one second evaluation unit for issuing a warning message based on data acquired by the second sensor.It is intended that at least one second sensor is designed to convert energy released by the energy storage device in the event of thermal propagation into an electrical signal for controlling at least one second evaluation device.

[0008] Furthermore, US patent 2022 / 0268851 A1 discloses a system comprising a battery cell containing a liquid electrolyte and an acoustic transducer mechanically connected to the battery cell. The acoustic transducer is configured to generate acoustic waves with a wavelength larger than one dimension of the battery cell, causing cavitation bubbles to form in the electrolyte.

[0009] Document FR 3 098 347 A1 relates to an electrochemical cell for a lithium battery comprising a negative electrode, a positive electrode, and a separator. Furthermore, hollow objects comprising one or more thermally expandable polymers are provided, the hollow objects being arranged between the negative and positive electrodes.

[0010] In “Introduction to Ultrasound, Sonochemistry and Sonoelectrochemistry” by Bruno Pollet & Muthupandian Ashokkumar (SpringerBriefs in Molecular Science, 2019), it is shown how ultrasound waves interact with gas bubbles in liquids to generate cavitation, and how the high temperatures that arise in the cavitation bubbles can be estimated.

[0011] CN 1 17 276 654 A relates to the field of secondary batteries, and specifically relates to an ultrasound-assisted in-situ polymerization process of a solid-state battery precursor solution and its application.

[0012] US Patent 2011 / 0 172 486 A1 relates to a method for producing a suspension of microbubbles, wherein the structural parameters of the microbubbles in the suspension have been optimized for use in a method for the targeted delivery of a therapeutic agent, which includes magnetic actuation of the microbubbles and ultrasonic exposure to rupture the microbubbles. The invention also relates to the magnetic microbubbles themselves and their use, as well as methods and a computer program for determining an optimized microbubble design.

[0013] The invention is based on the objective of enabling particularly safe operation of a battery. In particular, it aims to reduce the risk to a user of the battery and / or to the battery itself in the event of thermal runaway in a battery cell.

[0014] This problem is solved according to the invention by a battery having the features of claim 1. Furthermore, this problem is solved according to the invention by a method having the features of claim 8 and by a motor vehicle having the features of claim 10. Advantageous embodiments and further developments are the subject of the dependent claims.

[0015] The battery is specifically designed and configured for use in a motor vehicle. For example, the battery is a traction battery (high-voltage battery) which provides electrical energy for a drive system.

[0016] The battery comprises a battery cell, which is in particular designed as a lithium-ion battery cell. Advantageously, the battery includes a plurality of such battery cells, for example, between 50 and 200. Each battery cell, in turn, has an electrolyte, in particular a liquid one, containing a polymerizable and / or organic, i.e., non-aqueous, solvent. In particular, the battery cell is filled with the electrolyte.

[0017] For example, the molecules of the solvent for this purpose each comprise a CH bond, a CC double bond (C=C bond), a CC triple bond (C=C bond), and / or a C=O bond, which lead to the formation of polycarbonates.

[0018] The battery cell also contains (initial) nanobubbles within its interior, i.e., within its cell space, in other words, within the cell casing of the battery cell. Each nanobubble has a shell and contains a substance for the polymerization of the solvent, which is enclosed within the shell. This substance, hereinafter also referred to as the polymerization agent, is designed and intended to initiate and / or accelerate the polymerization of the solvent.

[0019] Furthermore, the battery cell includes a sensor for detecting a state variable of the battery cell. For example, the sensor is a temperature sensor, a pressure sensor, or a gas sensor. Alternatively, the sensor is such as that disclosed in DE 10 2020 200 011 A1 cited above, i.e., for example, a thermoelectric sensor, a pyroelectric sensor, a photosensor, or a bimetallic switch.

[0020] Furthermore, the battery cell includes an ultrasonic generator. This generator is designed and configured to produce ultrasound within the battery cell, i.e., inside the cell itself. For this purpose, the ultrasonic sensor is, for example, directly coupled to a housing of the battery cell. Alternatively, the ultrasonic sensor is coupled to a cell module housing or module frame, whereby the cell module housing or the module frame is coupled to the battery cell in such a way that the ultrasonic waves generated by the ultrasonic generator are transmitted into the battery cell.

[0021] The battery cell format can be a pouch cell, a prismatic cell or a cylindrical cell, as long as it is coupled to the ultrasound generator in such a way that ultrasound waves can be generated in or transmitted into the battery cell by means of the ultrasound generator.

[0022] The ultrasound generator is controlled in such a way that ultrasound is generated within the battery cell, and thus within the nanobubbles, depending on the state variable of the battery cell detected by the sensor. Specifically, ultrasound is generated when a critical state of the battery cell is detected, which occurs particularly during thermal propagation and / or thermal runaway, or indicates such thermal propagation and / or thermal runaway. For example, ultrasound is generated when the state variable detected by the sensor, such as temperature or pressure within the battery cell, exceeds a predefined threshold. The generation of ultrasound, i.e., the ultrasonic waves, serves to release the polymerization agent (polymerizing agent) through cavitation of the polymerization agent.Within each nanobubble, the polymerization agent is at least partially vaporized by the ultrasound waves. Due to the resulting increase in volume and / or the subsequent collapse of the vapor bubbles, the shell is damaged, in particular, it ruptures, and / or the nanobubble bursts. Consequently, the polymerization agent is released and comes into contact with the solvent, causing it to polymerize. This, in turn, results in a reduction of the ion mobility within the battery cell and thus an increase in internal resistance. The electric current through the battery cell is therefore reduced. This is particularly advantageous because it prevents and / or at least delays thermal events, such as thermal propagation and / or thermal runaway.

[0023] For example, a suitable frequency and / or intensity is stored in a control unit's memory, which then controls the ultrasound generator accordingly, causing it to produce ultrasound of this frequency and / or intensity. This frequency and / or intensity is, for example, determined in advance through experiments and / or is known from the prior art for the polymerization material used.

[0024] The frequency of the ultrasound waves is chosen, for example, between 20 kHz and 10 MHz, and in particular between 20 kHz and 1 MHz.

[0025] In a suitable battery design, the nanobubbles are incorporated into the electrolyte. For example, the nanobubbles are mixed with the electrolyte solvent, or in particular, dissolved within it. Advantageously, the nanobubbles are added to the electrolyte like an additive. During manufacturing, for instance, the electrolyte containing the nanobubbles is produced and then filled into the battery cell. This advantageously results in a relatively uniform distribution of the nanobubbles within the battery cell.

[0026] Additionally or alternatively, the nanobubbles are applied to a separator that is positioned between the anode and cathode of the battery cell. For example, during manufacturing, the nanobubbles are applied to the separator, and then the separator with the nanobubbles is positioned between the anode and the cathode, and the resulting electrode assembly is inserted into the cell casing.

[0027] According to an advantageous embodiment, the battery cell has further nanobubbles (second nanobubbles) within its interior. Analogous to the first nanobubbles, these each contain a shell. However, within the shell of each of the second nanobubbles, a substance (polymer degradation agent) for the depolymerization of the polymerized solvent is incorporated, in particular enclosed. The polymer degradation agent is thus designed and configured to depolymerize the polymerized solvent. It is particularly advantageous that the polymer degradation agent reverses the previous polymerization of the solvent. Thus, the polymerized solvent is broken down again into smaller molecules, in particular into monomers.

[0028] The ultrasonic generator is advantageously controlled in such a way that, depending on the (current) state of the battery cell, ultrasonic waves are generated within the battery cell to release the substance for depolymerization of the polymerized solvent through cavitation. In particular, the ultrasound is generated when a state of the battery cell is detected that is no longer classified as critical and / or does not indicate thermal propagation and / or thermal runaway. For example, ultrasound is generated when the state variable detected by the sensor, especially the temperature or pressure in the battery cell, falls below a predefined threshold. The generation of the ultrasound, i.e., the ultrasonic waves, serves to release the polymer degradation substance through its cavitation.Thus, in each subsequent nanobubble, the polymer degradation material is at least partially vaporized by the ultrasound waves. Due to the associated increase in volume and / or the subsequent collapse of the corresponding vapor bubbles, the shell is damaged, in particular it ruptures, and / or the respective subsequent nanobubble bursts. Consequently, the polymer degradation material is released and comes into contact with the polymerized solvent, causing it to depolymerize.

[0029] Advantageously, the further nanobubbles are designed, in particular the shell material and / or the polymer degradation agent are selected, such that the polymer degradation agent is released at a different frequency and / or intensity than the polymerization agent. Advantageously, these frequencies and / or intensities are selected such that the polymerization agent is not also released (or at least only to a negligible extent) when the polymer degradation agent is released, and / or vice versa. Preferably, these frequencies and / or intensities differ by 10%, and in particular by at least 25%.

[0030] In summary, the additional nanobubbles enable a reversal of the polymerization process. As a result, the ionic conductivity of the battery cell is increased upon release of the polymer degradation material, allowing the battery cell to be reused for generating electricity. For example, this enables the continued operation of a vehicle containing the battery in an emergency mode, allowing further driving, such as to a repair shop, following thermal runaway and / or thermal propagation.

[0031] The additional nanobubbles are also conveniently introduced into the electrolyte and / or arranged on the separator of the battery cell.

[0032] Such shells of nanobubbles and / or further nanobubbles – also known as nanocapsules – are typically used in pharmaceuticals. The shell is formed, for example, by radical polymerization, desolvation, or emulsion diffusion. The loading with the active ingredient – ​​in this case, the polymerizing agent or the depolymerizing agent – ​​occurs, for example, through adsorption or adhesion during or after the shell's production.

[0033] Furthermore, methods for producing filled nanobubbles are known from the production of lithium-sulfur batteries.

[0034] According to a preferred embodiment – ​​and in particular where the nanobubbles and / or further nanobubbles are mixed with the electrolyte solvent, for example, dissolved therein, i.e., where the nanobubbles and / or further nanobubbles form a component of the electrolyte, particularly in the manner of an additive – the proportion of the nanobubbles and / or the proportion of further nanobubbles in the electrolyte is between 0.1 vol% and 2 vol%, advantageously between 0.2 vol% and 1 vol%. This provides sufficient substance for the polymerization or depolymerization of the solvent, thus delaying and / or preventing thermal runaway, or allowing the polymerization to be reversed so that the battery cell can subsequently be reused.

[0035] According to a preferred embodiment, the shells of the nanobubbles and / or the shells of further nanobubbles are each formed using a polyalkyl compound, for example, polyalkyl methacrylate. Advantageously, the shell is formed from a monomolecular or a bimolecular layer, in particular from such a polyalkyl compound.

[0036] The nanobubbles and / or the further nanobubbles have, for example, an outer diameter, particularly an average diameter, between 0.5 nm and 1000 nm, especially between 1 nm and 20 nm.

[0037] According to a suitable embodiment, the substance for polymerizing the solvent contains persistent radicals, such as TEMPO (2,2,6,6-tetramethylpiperidinyloxyl). For example, this substance is dissolved in a solvent. Additionally or alternatively, the substance for polymerizing the solvent contains radical initiators, i.e., molecules that readily decompose into radicals, such as organic peroxo compounds. For example, this substance is dissolved in a solvent.

[0038] According to a suitable embodiment, the substance comprises an oxidizing agent for the depolymerization of the polymerized solvent. For example, a peroxosulfate is used as the oxidizing agent. This substance is, for example, dissolved in a solvent.

[0039] For example, the battery cell comprises nanobubbles containing persistent radicals and further nanobubbles containing the oxidizing agent. It also comprises nanobubbles containing radical initiators and further nanobubbles containing the oxidizing agent.

[0040] Another aspect of the invention relates to a method for operating a battery. In particular, this battery is configured according to one of the variants described above. The descriptions relating to the battery then apply accordingly. The battery may optionally comprise a battery cell with an electrolyte containing a polymerizable solvent.

[0041] The procedure involves first recording a state variable of the battery cell, particularly using the sensor. This state variable is then appropriately evaluated using a control unit.

[0042] Furthermore, depending on the detected state variable, particularly if the detected state variable indicates a critical battery condition and / or such a condition is determined as a result of the evaluation, a (polymerizing) agent is released to polymerize the solvent in the battery cell. For this purpose, an ultrasonic generator, preferably controlled by the control unit, is activated in such a way that ultrasonic waves are generated in the battery cell, causing cavitation in the polymerizing agent. Due to the cavitation, a shell encompassing and, in particular, enclosing the polymerizing agent is ruptured, allowing the polymerizing agent to react with the solvent. Advantageously, a multitude of nanobubbles are present in the battery cell, each containing such a shell with the polymerizing agent contained within it.

[0043] The state variable of the cell is expediently recorded continuously or at successive intervals, particularly using the sensor, and the state variable is evaluated.

[0044] According to an advantageous embodiment of the process, it is particularly advantageous, depending on the state variable, if, following the release of the polymerizing agent, the state determined on the basis of the state variable is no longer defined as a critical state, or if, after a predetermined period of time, a (polymer degradation) substance is released for the depolymerization of the polymerized solvent in the battery cell.

[0045] Another aspect of the invention relates to a motor vehicle which has a battery which is designed according to one of the (battery) variants shown above, and / or which can be operated and / or is operated according to the method in one of the (method) variants shown above.

[0046] In particular, the motor vehicle is an electrically powered motor vehicle, where the battery is the traction battery of the motor vehicle. The traction battery thus provides electrical energy for a traction drive, in particular for its traction electric motor.

[0047] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. The drawing shows: Fig. 1 schematically a battery comprising a battery cell with an electrolyte and an ultrasonic generator coupled to the battery cell, Fig. 2a schematically a nanobubble dissolved in a solvent of the electrolyte, wherein the nanobubble has a shell and a substance enclosed by it for polymerizing the solvent, Fig. 2b schematically a further nanobubble dissolved in the solvent of the electrolyte, wherein the further nanobubble has a shell and a substance enclosed therein for depolymerizing the polymerized solvent, and Fig. 3. A flowchart shows the process flow for operating a battery.

[0048] Corresponding parts and sizes are always marked with the same reference symbols in all figures.

[0049] In the Fig. Figure 1 schematically depicts a battery 2. This comprises at least one battery cell 4. Advantageously, the battery 2 comprises a plurality of battery cells 4 connected electrically in series and / or parallel to one another. The following explanations then apply analogously.

[0050] The battery cell 4 has a cell housing 6, which encloses a cell interior. An electrode arrangement consisting of at least one anode 8, at least one cathode 10, and a separator 12 between each of the at least one anode 8 and the at least one cathode 10 is accommodated within the cell interior. Furthermore, the battery cell 4 contains an electrolyte, which is contained in the Fig. 1 is generally designated with the reference numeral 14.

[0051] The liquid electrolyte 14 again comprises a conducting salt (not shown in detail) and a solvent 16 in which the conducting salt is dissolved. The solvent 16 is an organic solvent 16, which is polymerizable.

[0052] Perfluoroethylene carbonate, for example, is used as a solvent.

[0053] Within the battery cell 4, i.e., in the cell interior, a large number of first nanobubbles 18 are also incorporated. According to an embodiment not shown in detail, these are applied to the separator 12. Additionally or alternatively, the first nanobubbles 18 – as particularly in the Fig. 2a is recognizable - dissolved in the solvent 16.

[0054] The first nanobubbles 18, also referred to as nanocapsules, comprise a shell 20, which is formed, for example, from a polyalkyl compound, in particular from a polyalkyl compound such as polyalkyl methacrylate. The shell 20 is formed, in particular, from a monomolecular or a bimolecular layer of the polyalkyl compound.

[0055] Each of the first nanobubbles 18 contains a substance 22 for the polymerization of the solvent 16. This substance 22, hereinafter referred to as the polymerization substance 22, is enclosed by the shell. Advantageously, the polymerization substance 22 is liquid. The substance 22 is designed and configured to initiate and / or accelerate the polymerization of the solvent 22 when it escapes from the shell 20, in other words, when it is released. The polymerization substance 22 is or comprises persistent radicals, such as TEMPO, and / or radical initiators, such as organic peroxo compounds (organic peroxides).

[0056] Optionally, a multitude of second nanobubbles 24 are also incorporated in the battery cell 4, i.e., in the cell interior. According to an embodiment not shown in detail, these are applied to the separator 12. Additionally or alternatively, the second nanobubbles 24 – as shown in particular in the Fig. 2b is recognizable - dissolved in the solvent 16.

[0057] The second nanobubbles 18, also referred to as nanocapsules, comprise a shell 20 analogous to the first nanobubbles. This shell is formed, for example, from a polyalkyl compound, in particular from a polyalkyl compound such as polyalkyl methacrylate. The shell 20 is formed, in particular, from a monomolecular or a bimolecular layer of the polyalkyl compound.

[0058] Each of the second nanobubbles 24 contains a substance 26 for the depolymerization of the polymerized solvent 16. This substance 26, hereinafter referred to as the depolymerizing agent 26 or polymer degradation agent 26, is enclosed by the shell 20. Advantageously, the polymer degradation agent 26 is liquid. The substance 22 is designed and configured to initiate and / or accelerate the depolymerization of the solvent 16 polymerized by the substance 22 when it escapes from the shell 20, in other words, when it is released. The polymer degradation agent 26 is or comprises an oxidizing agent, such as peroxosulfate.

[0059] The proportion of the first nanobubbles 18 and, if applicable, the further nanobubbles 24 in the electrolyte is between 0.1 vol% and 2 vol%, in particular between 0.2 vol% and 1 vol%.

[0060] Furthermore, battery 2 has a sensor 28. This sensor is designed to determine whether thermal runaway and / or thermal propagation is occurring in battery cell 4. For this purpose, sensor 28 is configured, for example, as a temperature sensor, a pressure sensor, or a current sensor.

[0061] Sensor 28 is connected to a control unit 30 via signal and / or data transmission. Consequently, measurement data and / or signals acquired by the sensor can be transmitted to the control unit 30 and evaluated by the control unit 30. The measurement data and / or signals represent a state variable S of the battery cell. Thus, the state variable S is transmitted to the control unit 30 as measurement data and / or signals.

[0062] An ultrasound generator 32 is coupled to the battery cell in such a way that ultrasound, i.e., ultrasound waves, of a predetermined frequency and / or intensity can be generated by the ultrasound generator 32. The ultrasound generator 32 is thus mechanically coupled to the battery cell 4. For example, the ultrasound generator 32, as shown in the Fig. As shown in Figure 1, the ultrasonic generator 32 is arranged directly on the battery cell 4. According to an alternative not shown, the ultrasonic generator 32 is arranged on a cell module housing or module frame in which the battery cell and, optionally, further battery cells are housed. The module frame or cell module housing is mechanically coupled to the battery cell 4 in such a way that the ultrasonic waves generated by the ultrasonic generator 32 are transmitted from the module frame or cell module housing to the battery cell 4.

[0063] The ultrasound generator 32 is coupled to the control unit 30 via signal and / or data transmission. The ultrasound generator 32 can therefore be controlled by the control unit 30.

[0064] For example, control unit 30 is the so-called battery management system (BMS) of battery 2.

[0065] The ultrasonic generator 32 is and / or is controlled by the control unit 30 in such a way that ultrasonic waves are generated in the battery cell 4 for the release of the substance 22 for the polymerization of the solvent 16 due to cavitation, particularly if it has been determined, especially on the basis of the 30, that the state of the battery cell 4, as determined by the state variable S, is a critical state, for example, a state such as occurs during thermal runaway and / or thermal propagation. For example, a measurement signal supplied by the sensor 28 or measurement data representing a pressure (pressure state) or a temperature (temperature state) in the battery cell 4 as the state variable S are compared by the control unit 30 with a predetermined threshold value, whereby a critical state of the battery cell 4 is detected if the threshold value is exceeded.

[0066] The frequency and / or intensity suitable for cavitation of the polymerizing agent 22 is expediently stored on a memory of the control unit 30 or the ultrasound generator 32, which is not shown further.

[0067] Provided that the additional nanobubbles 24 are present in the battery cell, the ultrasonic generator 32 is and / or continues to be controlled by the control unit 30 such that ultrasonic waves are generated in the battery cell 4. These ultrasonic waves serve to release the substance 26 for the depolymerization of the polymerized solvent 16 due to cavitation. Advantageously, these ultrasonic waves are generated when, in particular based on the 30, it has been determined that the state of the battery cell 4, as determined by the state variable S (especially after re-measurement of the state variable S), is no longer considered critical, i.e., when the state variable S does not indicate thermal propagation and / or thermal runaway.For example, ultrasound is generated when a temperature or pressure measured by the sensor, as a state variable S, falls below a predefined threshold for a predefined period of time. Advantageously, the measurement signal or data supplied by sensor 28, representing a pressure (pressure state) or temperature (temperature state) in battery cell 4, is compared with a predefined threshold by the control unit 30. If this threshold is not met, a non-critical state of battery cell 4 is detected.

[0068] The frequency and / or intensity suitable for cavitation of the polymer degradation substance 26 is expediently stored on the memory of the control unit 30 or the ultrasonic generator 32, which is not shown further.

[0069] Advantageously, the further nanobubbles 24 are designed in such a way that, in particular, the material of the shell 20 and / or the polymer degradation substance 26 is released at a different frequency and / or at a different intensity than the polymerization substance 22.

[0070] For example, TEMPO is used as a polymerizing agent 22 and / or dimethyl peroxodisulfate as a polymer degradation agent 26. The intensity and / or frequency suitable for the release of the respective substance 22, 26 is, for example, the intensity and / or frequency known in advance for generating cavitation from the prior art and / or the intensity and / or frequency has been determined experimentally in advance.

[0071] The control unit 30 serves to carry out a procedure as described in connection with the Fig. 3 is described. The 30 is therefore configured to evaluate the measurement data and / or measurement signals supplied by the sensor 28, in particular to determine whether thermal runaway or thermal propagation is occurring. Specifically, the control unit 30 is further configured to control the ultrasonic generator depending on the state variable S such that ultrasonic waves are generated to cavitate the polymerization material and thus release it, if the state of the battery cell 4, determined based on the state variable S, corresponds to thermal runaway or thermal propagation.In particular, the control unit 30 is further configured to control the ultrasonic generator depending on the state S such that ultrasonic waves are generated for cavitation of the polymer degradation substance, and thus for its release, when the state S does not correspond to thermal runaway or thermal propagation in order to depolymerize the polymerized solvent 16.

[0072] In the Fig. Figure 3 shows a process for operating a battery 2, which according to the Fig. 1 to 2b is trained.

[0073] In the first step (I) of the process, a state variable S of battery cell 4 is detected using the sensor. The state variable S is, for example, a temperature or pressure in battery cell 4. This state variable S is transmitted to the control unit 30 as a measurement signal or as measurement data.

[0074] In a subsequent second step II, the state variable S is evaluated, particularly with regard to the control unit 30. If the evaluation reveals a critical state of the battery cell, specifically that thermal propagation or thermal runaway is occurring, the control unit 30 activates the ultrasonic generator 32 such that ultrasonic waves of a frequency and / or intensity stored in a memory are generated in the battery cell 4. This frequency and / or intensity is designed and suitable to induce cavitation and the associated release of the polymerizing agent 22. As a result of this release, the polymerizable solvent polymerizes, thus stopping or at least delaying thermal propagation or thermal runaway.

[0075] In summary, depending on the measured state variable S, the substance 22 is released for the polymerization of the solvent 16 in the battery cell 4 due to cavitation.

[0076] In a subsequent third step III, the state variable S is again detected using the sensor 28 and transmitted to the control unit 30.

[0077] Subsequently, in a fourth step IV, the (re-acquired) state variable S is evaluated, in particular using the control unit 30. If the evaluation reveals, in particular, that thermal propagation or thermal runaway has stopped, then the ultrasonic generator 32 is controlled by the control unit 30 such that ultrasonic waves of a further frequency and / or intensity stored in a memory are generated in the battery cell 4. This further frequency and / or intensity is designed and suitable to cause cavitation and the associated release of the polymer degradation substance 26. As a result of the release, the polymerized solvent depolymerizes, so that the battery cell 4 can again be used to provide electrical energy.

[0078] According to an alternative not shown further, the state variable S is not measured again (step III is therefore omitted). After a predetermined time period, the ultrasonic generator 32 is then controlled by the control unit 30 such that ultrasonic waves of a further frequency and / or further intensity are generated in the battery cell 4.

[0079] In summary, depending on the state variable S, the substance 26 is released for the depolymerization of the polymerized solvent 16 in the battery cell 4.

[0080] In a manner not shown in detail, a motor vehicle, in particular an electrically powered one, comprises a battery 2 which, according to the Fig. 1 to 2b trained and / or in accordance with the Fig. 3 is operated. Battery 2 is conveniently a traction battery, meaning it provides electrical energy to power the vehicle.

[0081] The invention is not limited to the embodiments described above. Rather, other variants of the invention can also be derived by a person 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 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. Reference symbol list 2 batteries 4 battery cells 6 cell casings 8 Anode 10 Cathode 12 Separator 14 Electrolyte 16 solvents 18 nanobubbles 20 cases 22 Substance for polymerizing the solvent 24 more nanobubbles 26 Substance for depolymerization of the polymerized solvent 28 Sensor 30 control unit 32 Ultrasound generator S State variable of the battery cell I. Determining the battery's condition 11 Polymerization of the solvent III. Re-assessing the battery's condition IV. Depolymerization of the solvent

Claims

[1] Battery (2), in particular a traction battery for an electrically powered motor vehicle, comprising - a battery cell (4) with an electrolyte (14) comprising a polymerizable solvent (16), - wherein the battery cell (4) has nanobubbles (18) inside its cell, each of which has a shell (20) and a substance (22) incorporated therein for polymerizing the solvent (16), - a sensor (28) for detecting a state variable (S) of the battery cell (4), and - an ultrasound generator (32) for generating ultrasound in the battery cell (4), - wherein the ultrasound generator (32) is controlled and / or is controlled such that, depending on the state variable (S) of the battery cell (4), in particular when a state variable (S) representing a critical state of the battery cell (4) is detected, ultrasound waves are generated in the battery cell (4) for the release of the substance (22) for polymerization of the solvent (16) due to cavitation. [2] Battery (2) according to claim 1, characterized by , that the nanobubbles (18) are introduced into the electrolyte (14) and / or that the nanobubbles (18) are arranged on a separator (12) of the battery cell (4). [3] Battery (2) according to claim 1 or 2, characterized by , - the battery cell (4) in the interior of which further nanobubbles (24) have a shell (20) and a substance (26) contained therein for the depolymerization of the polymerized solvent (16), and / or - wherein the ultrasonic generator (32) is controlled and / or is controlled such that, depending on the state variable (S) of the battery cell (4), ultrasonic waves are generated in it to release the substance (26) for the depolymerization of the polymerized solvent (16) due to cavitation, and / or - wherein the further nanobubbles (24) are designed such that the substance (26) for depolymerization of the polymerized solvent (16) is released at a different frequency and / or intensity than the substance (PM) for polymerization of the solvent (16). [4] Battery (2) according to any one of claims 1 to 3, characterized by , that the proportion of the nanobubbles (18) and / or the further nanobubbles (24) in the electrolyte is between 0.1 vol% and 2 vol%, in particular between 0.2 vol% and 1 vol%. [5] Battery (2) according to any one of claims 1 to 4, characterized by, that the shells (20) of the nanobubbles (18) and / or the shells (20) of the further nanobubbles (24) are formed using a polyalkyl compound. [6] Battery (2) according to any one of claims 1 to 5, characterized by , that the substance (22) contains persistent radicals and / or radical initiators for the polymerization of the solvent (16). [7] Battery (2) according to any one of claims 3 to 6, characterized by , that the substance (26) contains an oxidizing agent for the depolymerization of the polymerized solvent. [8] Method for operating a battery (2), in particular designed according to one of claims 1 to 7, which has a battery cell (4) with an electrolyte (14) with a polymerizable solvent (16), - wherein a state variable (S) of the battery cell (4) is recorded, and - wherein, depending on the detected state variable (S), in particular when detecting a state variable (S) representing a critical state of the battery cell, a substance (22) is released for the polymerization of the solvent (16) in the battery cell (4), in particular due to cavitation. [9] Method according to claim 8, characterized by , that, in particular depending on the state variable (S), a substance (26) is released to depolymerize the polymerized solvent (16) in the battery cell (4). [10] Motor vehicle with a battery (2) designed according to one of claims 1 to 7 and / or operable and / or operated according to the method according to one of claims 8 or 9.

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