BATTERY STORAGE WITH A SAFETY DEVICE AND METHOD FOR TRIGGERING THE SAFETY DEVICE

Description

[0001] The present invention relates to a battery storage device with a safety device and a method for triggering the safety device.

[0002] Electrochemical cells are of great importance in many technical fields. For example, they are frequently used in mobile applications such as powering laptops, e-bikes, and mobile phones. One advantage of electrochemical cells is that they can be connected in series or parallel to form batteries with higher energy capacities. Such batteries can be combined in a battery storage system and are also suitable for high-voltage applications. For example, battery storage systems can power electric vehicles or be used as stationary energy storage devices.

[0003] In the following, the term "electrochemical cell" is used synonymously for all terms commonly used in the prior art for rechargeable galvanic elements, such as cell, battery, battery cell, accumulator, battery accumulator and secondary battery.

[0004] An electrochemical cell is capable of supplying electrons to an external circuit during discharge. Conversely, an electrochemical cell can be charged by supplying electrons to an external circuit during charging.

[0005] An electrochemical cell has at least two different electrodes: a positive electrode (cathode) and a negative electrode (anode). Both electrodes are in contact with a separator, which is an electrical insulator. For example, a porous polyolefin separator impregnated with a liquid electrolyte is used in state-of-the-art applications. The separator spatially separates the two electrodes and connects them via an ion-conducting connection.

[0006] The most commonly used electrochemical cell is the lithium-ion cell, also called a lithium-ion battery. State-of-the-art lithium-ion cells typically have a composite anode, very often consisting of a carbon-based anode active material, typically graphitic carbon, which is usually coated with an electrode binder onto a metallic copper substrate. The composite cathode usually consists of a positive cathode active material, for example, a layered oxide, a binder, and an electrical conductivity additive, which are applied, for example, to a rolled aluminum collector foil. The layered oxide very often consists of LiCoO₂ or LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O₂.

[0007] Lithium-ion batteries typically have a liquid electrolyte composition that ensures charge balance between the cathode and anode during charging and discharging. The necessary current flow is achieved through the ion transport of a conducting salt within the electrolyte. In lithium-ion cells, this conducting salt is a lithium conducting salt (e.g., LiPF₆, LiBF₄), and the dissociated lithium ions move in the electric field between the electrodes.

[0008] In addition to the lithium conducting salt, electrolyte compositions contain a solvent that enables dissociation of the conducting salt and sufficient mobility of the lithium ions. Liquid organic solvents consisting of a selection of linear and cyclic dialkyl carbonates are known from the prior art. Typically, mixtures of ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), propylene carbonate (PC), and ethyl methyl carbonate (EMC) are used. The solvents mentioned here each exhibit a specific stability range within which they operate stably under a given cell voltage. This range is also known as the voltage window. Within this voltage window, the electrochemical cell can operate stably. As the limits of the voltage window are approached, electrochemical oxidation or reduction of the components of the electrolyte composition occurs.Therefore, efforts are being made to use electrolytes that exhibit higher stability across different cell voltages.

[0009] Lithium-ion batteries with an inorganic electrolyte based on sulfur dioxide solvent represent a further development of lithium-ion batteries with an organic electrolyte. Various approaches for stable electrolyte compositions based on sulfur dioxide are known in the prior art.

[0010] EP 1 201 004 B1 discloses a rechargeable electrochemical cell with a sulfur dioxide-based electrolyte. Sulfur dioxide is not added as an additive, but rather constitutes the main component as a solvent for the conducting salt in the electrolyte composition. Therefore, it is intended to at least partially ensure the mobility of the lithium ions in the conducting salt, which facilitate ion transport between the electrodes. In the proposed cells, lithium tetrachloroaluminate (LiAlCl₄) is used as the lithium-containing conducting salt in combination with a cathode active material made of a transition metal oxide, in particular an intercalation compound such as lithium cobalt oxide (LiCoO₂). Functional and rechargeable cells were obtained by adding a salt additive, for example, an alkali halide such as lithium fluoride, sodium chloride, or lithium chloride, to the sulfur dioxide-containing electrolyte composition.

[0011] EP 2 534 719 B1 describes a rechargeable lithium battery cell with a sulfur dioxide-based electrolyte in combination with lithium iron phosphate (LFP) as the cathode active material. Lithium tetrachloroaluminate was used as the preferred conducting salt in the electrolyte composition. Tests with cells based on these components demonstrated high electrochemical stability.

[0012] WO 2015 / 043573 A2 describes a rechargeable electrochemical battery cell comprising a casing, a positive electrode, a negative electrode and an electrolyte containing sulfur dioxide and a conducting salt, wherein at least one of the electrodes contains a binder selected from the group consisting of binder A, which consists of a polymer composed of monomeric structural units of a conjugated carboxylic acid or of the alkali, alkaline earth or ammonium salt of this conjugated carboxylic acid or of a combination thereof, and binder B, which consists of a polymer based on monomeric styrene and butadiene structural units or of a mixture of binder A and B.

[0013] WO 2021 / 019042 A1 describes rechargeable battery cells with an active metal, a layered oxide as the cathode active material, and a sulfur dioxide-containing electrolyte. Due to the poor solubility of many common lithium conducting salts in sulfur dioxide, a conducting salt of the formula M+ [Z(OR)4]- was used in the cells, where M is a metal selected from the group consisting of alkali metals, alkaline earth metals, and a metal of group 12 of the periodic table, and R is a hydrocarbon residue. The alkoxy groups -OR are monovalently bonded to the central atom, which can be aluminum or boron. In a preferred embodiment, the cells contain a perfluorinated conducting salt of the formula Li+ [Al(OC(CF3)3)a]-. Cells consisting of the described components exhibit stable electrochemical performance in experimental studies.Furthermore, the conducting salts, especially the perfluorinated anion, exhibit surprising hydrolysis stability. The electrolytes are also reported to be oxidation-stable up to an upper potential of 5.0 V. It has also been shown that cells using the disclosed electrolytes can be discharged and charged at low temperatures down to -41°C.

[0014] Furthermore, the unpublished German patent application No. 10 2021 118 811.3 discloses a liquid electrolyte composition based on sulfur dioxide for an electrochemical cell. The electrolyte composition comprises the following components: A) sulfur dioxide; B) at least one salt, wherein the salt contains an anionic complex with at least one bidentate ligand. The counterion of the anionic complex is a metal cation selected from the group consisting of alkali metals, alkaline earth metals, and metals of group 12 of the periodic table. The central ion Z of the complex is selected from the group consisting of aluminum and boron. The bidentate ligand forms a ring with the central ion Z and with two oxygen atoms bonded to the central ion Z and the bridging residue, the ring containing a continuous sequence of 2 to 5 carbon atoms.Furthermore, an electrochemical cell, in particular a lithium-ion cell, with the aforementioned electrolyte composition was proposed.

[0015] Furthermore, cells with an electrolyte based on sulfur dioxide are known from EP 3 703 161 A1, EP 2 227 838 B1, EP 2 742 551 B1, EP 3 771 011 A2, WO 2005 / 031908 A2 and WO 2014 / 121803 A1, which are referenced here.

[0016] EP 3 734 724 A1 discloses a rechargeable battery cell with an electrolyte based on sulfur dioxide.

[0017] JP 2003 036883 A describes a sodium-sulfur battery which includes an absorber for gaseous sulfur dioxide to prevent sulfur dioxide from escaping the battery.

[0018] From WO 2020 / 065035 A1, a process for neutralizing or reducing odors or gases, for example gaseous sulfur dioxide, is known, wherein a composition is used that comprises one or more highly esterified and / or highly methylated pectins and at least one organic acid or its salts.

[0019] WO2014 / 077536 A1 discloses a battery storage device which has a safety device with a metering device, wherein the safety device includes an additive for neutralizing gases inside the storage housing.

[0020] In the event of a mechanical, electrical or thermal defect of the battery cells, especially lithium-ion cells with an electrolyte composition based on sulfur dioxide, the cell may open and thus electrolyte components may be released from the cell, especially gaseous electrolyte components such as sulfur dioxide.

[0021] The invention is based on the objective of preventing the electrolyte from leaking into the environment in the event of such damage to a cell with an electrolyte based on sulfur dioxide.

[0022] The problem is solved according to the invention by a battery storage device with a safety device and at least one battery cell according to claim 1.

[0023] Advantageous embodiments of the battery storage system according to the invention are specified in the dependent claims and the figures, which can be optionally combined with one another.

[0024] According to the invention, the problem is solved by a battery storage device comprising a storage housing and at least one battery cell arranged in an interior of the storage housing and containing an electrolyte based on sulfur dioxide, wherein the battery storage device has a safety device with a metering device comprising a foaming additive and is configured to generate a foam from the foaming additive for neutralizing the electrolyte and to release the foam in the interior of the storage housing.

[0025] The basic idea of ​​the invention is that, in the event of a mechanical, thermal or electrical defect of a cell, the proposed battery storage device has a safety device that neutralizes or binds any electrolyte based on sulfur dioxide that escapes from a cell by releasing a foam.

[0026] This provides the technical advantage that the escaping electrolyte can be quickly and safely absorbed by the large surface area of ​​the foam and easily neutralized or bound.

[0027] In this context, electrolyte neutralization refers to a chemical neutralization process that converts the electrolyte components, especially sulfur dioxide, into chemically more stable and less toxic compounds.

[0028] Furthermore, this offers the advantage that electrolyte neutralization takes place within the storage housing. Since the storage housing is designed to be liquid-tight, the foam, electrolyte, and other components remain inside the battery after neutralization. The storage housing thus provides a defined and spatially confined reaction chamber in which chemical neutralization can be carried out under controlled conditions. Advantageously, after neutralization is complete, the battery can be disposed of individually or recycled.

[0029] The technical advantage of using foam lies particularly in its ability to fix the escaping electrolyte. Individual electrolyte components can bind to the foam's bubble membrane through sorption and are thus trapped within the foam. Electrolyte components can also be stored within the foam's bubbles. In both cases, the escaping electrolyte's movement is restricted, and it can be quickly contained within the storage housing. Furthermore, the electrolyte, thus fixed, can be neutralized due to the foam's chemical properties. More precisely, the electrolyte can undergo a chemical reaction with the foam components, thereby neutralizing it and converting it into more chemically stable compounds. Because the foam simultaneously fixes the electrolyte, a particularly complete and efficient neutralization of the electrolyte can occur.

[0030] The proposed battery storage system is preferably arranged in a vehicle and serves to power its electric drive. Of course, multiple battery storage systems can also be arranged in such a vehicle. The battery storage system according to the invention is not limited to mobile applications such as vehicles and can also be used for stationary operation. For example, the battery storage system according to the invention can be used to store energy from solar power plants and wind farms.

[0031] For the purposes of the invention, a battery storage device is understood to be a storage housing in the interior of which at least one battery cell, preferably several battery cells, is arranged. The battery cells can be interconnected within the storage housing to provide a higher energy capacity. A battery cell is understood to be an electrochemical cell with an electrolyte based on sulfur dioxide. Preferably, the battery cell is a lithium-ion cell.

[0032] The invention is not further restricted with regard to the electrolyte composition based on sulfur dioxide. Therefore, all electrolyte compositions based on sulfur dioxide that are common in the prior art can be used.

[0033] In particular, a sulfur dioxide-based electrolyte is understood to be a liquid electrolyte composition that contains sulfur dioxide as a component. The sulfur dioxide can be present in the electrolyte composition in liquid, gaseous, or bound in a complex.

[0034] Suitable examples of such electrolyte compositions are known from EP 1 201 004 B1, EP 2 534 719 B1, WO 2015 / 043573 A2, WO 2021 / 019042 A1, EP 3 703 161 A1, EP 2 227 838 B1, EP 2 742 551 B1, EP 3 771 011 A2, WO 2005 031908 A2 and WO 2014 121803 A1, as well as from the unpublished German patent application No. 10 2021 118 811.3, to which reference is made here.

[0035] In an advantageous aspect of the invention, the foaming additive is present in an aqueous solution.

[0036] The foaming additive comprises at least one foaming agent. The invention is not further limited with respect to the foaming agent. In general, all foaming agents commonly used in the prior art can be used for the foaming additive.

[0037] Examples of foaming agents that can be used include protein foams, fluoroprotein foams, water film-forming protein foams, multi-range foams and alcohol-resistant foams.

[0038] Preferably, the foaming additive is selected from the group consisting of ionic surfactants, saponins and proteins, as well as combinations thereof.

[0039] Suitable examples of foaming agents include alkylbenzenesulfonate, fatty alcohol polyglycol ether sulfates, alkanesulfonates, alkyl ether carboxylates, betaines, fatty acid sulfoalkylamides, fatty acid sulfoalkyl esters, sodium lauryl sulfoacetate, sodium lauroyl sarcosinate, sodium lauryl ether sulfate, sodium dodecyl sulfate, coconut fatty acid monoglyceride sulfate, docusate sodium, sodium lauryl sulfoacetate, sodium lauroyl sarcosinate and sodium dodecyl sulfate, as well as combinations thereof.

[0040] The proposed foaming agents have the technical advantage of being inexpensive, readily available, and very miscible with water.

[0041] The foaming additive can comprise 0.1 - 6 wt.% of the foaming agent, preferably 4 - 6 wt.%, particularly preferably 5 - 6 wt.%, based on the total weight of the foaming additive.

[0042] The foaming additive further comprises a base. The invention is not further limited with respect to the base. In general, all bases commonly used in the prior art can be used for the foaming additive.

[0043] For example, the base can be a porous natural limestone.

[0044] Preferably, the base is selected from the group of carbonates, hydrogen carbonates, oxides and hydroxides, as well as combinations thereof.

[0045] Metal carbonates, especially alkali and alkaline earth metal carbonates, are used as carbonates. Suitable examples of carbonates include barium carbonate, calcium carbonate, magnesium carbonate, potassium carbonate, sodium carbonate, and zinc carbonate, as well as combinations thereof.

[0046] Metal hydrogen carbonates, especially alkali and alkaline earth metal hydrogen carbonates, are particularly suitable for use as hydrogen carbonates. Examples of suitable hydrogen carbonates include calcium hydrogen carbonate, magnesium hydrogen carbonate, barium hydrogen carbonate, strontium hydrogen carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate, as well as combinations thereof.

[0047] Metal oxides, particularly alkali and alkaline earth metal oxides, can be used as oxides. Suitable examples include lithium oxide, sodium oxide, potassium oxide, magnesium oxide, calcium oxide, strontium oxide, and barium oxide, as well as combinations thereof.

[0048] Metal hydroxides, especially alkali and alkaline earth metal hydroxides, are used as hydroxides. Examples of hydroxides include, in particular, lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, strontium hydroxide, and zinc hydroxide, as well as combinations thereof.

[0049] Since the foaming additive is present in an aqueous solution, the base is also present in an aqueous solution. Preferably, the base is dissolved in the aqueous solution.

[0050] In an advantageous embodiment of the invention, the aqueous solution is a solution saturated with the base. Due to the high base content, the saturated solutions exhibit a particularly high ion concentration. Preferably, the ion concentration corresponds to the solubility product of the respective base. Aqueous solutions with such a base concentration remain liquid even below the freezing point of water. Consequently, the base also serves as an antifreeze. Such saturated solutions are particularly suitable for operation or use in a vehicle.

[0051] The additive most preferably comprises a saturated aqueous solution of sodium carbonate, more preferably an aqueous saturated solution of potassium carbonate, and combinations thereof.

[0052] Providing a base in the foaming additive advantageously allows for direct neutralization of the electrolyte based on sulfur dioxide in the form of acid-base neutralization.

[0053] The sulfur dioxide contained in the electrolytes is highly soluble in water and can therefore be readily absorbed. The solubility of sulfur dioxide in water is 112.7 g per liter of water at 20°C. Sulfur dioxide reacts with water to form sulfurous acid, which can then react with the base in a neutralization reaction. The base can therefore convert the sulfur dioxide dissolved in the aqueous solution into more stable chemical compounds. For example, the sulfur dioxide can be converted by carbonates into stable sulfites or sulfates and / or hydrogen sulfites. Furthermore, the base offers the technical advantage of being non-toxic, readily soluble in water, and readily available.

[0054] Furthermore, the foaming additive may include other additives.

[0055] Suitable examples of additives include alkaline earth metal chlorides, flame retardants, higher alcohols, and urea, as well as combinations thereof. Higher alcohols are, in particular, saturated monohydric to trihydric alcohols with two to twelve carbon atoms, wherein the higher alcohols may have primary, secondary, or tertiary hydroxyl groups. Calcium chloride (CaCl₂) is particularly preferred as the alkaline earth metal chloride.

[0056] The addition of calcium chloride achieves the technical advantage that the sulfur dioxide absorption is increased by reaction to insoluble calcium sulfite.

[0057] In a further embodiment of the invention, the dosing device comprises a reservoir containing the foam-forming additive and a delivery pump connected to the reservoir. The delivery pump is connected to a foam distributor located inside the reservoir housing.

[0058] Preferably, the reservoir containing the foaming additive is arranged outside the storage housing. However, the reservoir can also be arranged inside the storage housing. The reservoir serves to store the foaming additive before the foam is formed and released within the storage housing.

[0059] Providing a storage container offers the advantage that the additive can be stored separately from the battery cells. This means the foaming additive can only be taken from the storage container when needed.

[0060] Preferably, the feed pump connected to the storage container is a high-pressure pump. The use of a high-pressure pump enables particularly rapid removal of the foaming additive from the storage container.

[0061] Furthermore, the pump is connected to a foam distributor. The invention is not further limited with respect to the foam distributor. In general, all foam distributors known in the prior art can be used that are suitable for releasing a foaming additive, in particular a foaming additive consisting of a foaming agent, at least one base and optionally further additives, into the interior of the storage housing.

[0062] For example, the foam distributor can comprise a line, preferably a flexible line, with nozzle outlets for distributing the foaming additive. Preferably, the nozzles enable atomization of the foaming additive, thereby advantageously increasing the contact area between the additive and the exiting electrolyte.

[0063] In another aspect of the invention, the safety device further comprises a monitoring device, wherein the monitoring device comprises a battery control system and a sensor unit connected to the battery control system.

[0064] The battery control system is preferably located outside the battery storage unit. It is therefore conceivable that the battery control system could monitor multiple battery storage units. A sensor unit, preferably located inside a storage unit housing, is connected to the battery control system.

[0065] In one embodiment, the sensor unit is selected from the group consisting of optical sensors, pressure, temperature and chemical sensors.

[0066] In one embodiment, the sensor unit is a spectroscopic gas sensor for detecting gaseous sulfur dioxide.

[0067] In a preferred embodiment, the spectroscopic gas sensor is a non-dispersive infrared sensor.

[0068] If abnormal behavior occurs in at least one battery cell during operation, this can be detected by the sensor types mentioned above. An increase in pressure, temperature, or a change in the atmospheric composition within the battery housing can thus be detected by the sensor unit. A defect in a battery cell can therefore be identified directly and without delay.

[0069] In particular, a gas sensor that selectively detects sulfur dioxide provides direct information about the presence of sulfur dioxide inside the battery housing. If the gas sensor detects sulfur dioxide in the atmosphere of the battery housing, the sulfur dioxide-based electrolyte has leaked from the battery cell, rendering the cell defective.

[0070] The data acquired by the sensor unit is forwarded to the battery control system connected to the sensor unit. Typically, the data sent to the battery control system consists of measurements collected over a specific time interval.

[0071] In another aspect of the invention, the battery control system is designed to receive data from the sensor unit and to evaluate this data with regard to a trigger or non-trigger scenario.

[0072] The battery control system receives data from the sensor unit and evaluates it to determine whether a battery cell within the storage housing is defective. Based on this data, the battery control system decides whether to trigger a trip or a non-trip scenario. If the battery control system registers abnormal data—specifically, data that deviates from the expected data—it initiates a trip. If the data received from the sensor unit matches the expected data, a non-trip scenario is selected.

[0073] In the event of a trigger scenario, the dosing device is activated by the battery control system, releasing the foaming additive through the foam distributor and thus creating foam within the storage housing. In the event of a non-trigger scenario, the status quo remains unchanged and the dosing device is not activated.

[0074] Preferably, the process described above takes place at regular time intervals. This allows the monitoring device to monitor the battery cells in real time, enabling the immediate and reliable detection of abnormal data such as pressure, temperature, and atmospheric parameters within the storage housing. Consequently, the battery control system can also take immediate action to release the additive within the battery storage system to neutralize any leaking electrolyte. Therefore, a safety device according to the invention, which includes a dosing device and a monitoring device, constitutes an active safety system.

[0075] In another embodiment, the metering device comprises a proportioner and a circulation pump, wherein the proportioner has a separate connection to the foam distributor, the feed pump and the circulation pump, and wherein the circulation pump is fluidly connected to the interior of the storage housing.

[0076] Typically, when foam is released within the storage housing, a sufficient amount of electrolyte cannot be immediately fixed and neutralized. The escaping electrolyte, which accumulates in the atmosphere of the storage housing over time, usually only comes into contact with the released foam through gas diffusion. The embodiment described above offers the advantage that a circulation pump is fluidically connected to the interior and thus to the atmosphere of the storage housing. This allows the atmosphere of the storage housing to be pumped out and returned to the storage housing via the proportioner and foam distributor. In other words, the atmosphere within the storage housing is circulated. This allows the sulfur dioxide-based electrolyte to be repeatedly brought into contact with the foam. In this way, almost complete neutralization of the electrolyte can be ensured.

[0077] In a further embodiment, the battery control system is configured to activate the metering device for the circulation pump when a trigger scenario occurs, so that it extracts a gas atmosphere present in the storage housing and feeds it back into the storage housing via the proportioner.

[0078] Preferably, the gas atmosphere extracted from the storage housing is returned to the storage tank via the proportioner and the foam distributor.

[0079] Linking the circulation pump to the monitoring device offers the technical advantage that, in addition to generating the foam, the circulation of the gas atmosphere in the storage housing can also be controlled.

[0080] Furthermore, the invention relates to a method for triggering a safety device for a battery storage system of the aforementioned type, wherein the method comprises the following steps: a) Detection of electrolyte leakage from a battery cell inside the storage housing by the monitoring device's sensor unit, generating data and forwarding it to the battery control system, b) Evaluation of the data by the battery control system regarding the presence of a trigger or non-trigger scenario, c) Detection of a trigger scenario, d) Control of the metering device, e) Generation of foam from the foaming additive, f) Release of the foam inside the storage housing, g) Optionally, observance of a waiting period, and h) Optionally, activation of a circulation pump that extracts any gas atmosphere present inside the storage housing and returns it to the interior via the proportioner and the foam distributor.

[0081] A safety device employing the aforementioned methods can thus react immediately to electrolyte leaking from a battery cell and take countermeasures. The released foam allows the sulfur dioxide-based electrolyte to be contained, and the base present in the foam can react with the electrolyte, particularly with sulfur dioxide, in a neutralization process. This reliably prevents the electrolyte from escaping into the environment.

[0082] The invention is described in more detail below with reference to exemplary embodiments and the accompanying drawings. The drawings show: Figure 1 in a schematic representation a battery storage system with battery cells, a dosing device and a monitoring device; Figure 2 in a schematic representation of the battery storage Figure 1during active operation in the event of electrolyte leaking from a defective battery cell; Figure 3 a schematic representation of a gas sensor for the selective detection of gaseous sulfur dioxide; Figure 4 an example of a suitable measuring range for the gas sensor Figure 3 ; and Figure 5 a schematic flowchart of the steps of a procedure for triggering a safety device for a battery storage system Figure 1 .

[0083] Figure 1 Figure 1 shows a battery storage device 10 with a safety device 32, 37. The safety device 32, 37 comprises a metering device 32 and a monitoring device 37.

[0084] The battery storage unit 10 also comprises a storage housing 12 and several battery cells 14 arranged in the interior 33 of the storage housing 12. The storage housing 12 is designed to be gas-tight.

[0085] At least one battery cell 14 is arranged in the interior 33. However, any number of battery cells 14 can be arranged within the storage housing 12. The battery cells 14 can be interconnected (not shown here) to provide a battery with a higher energy capacity.

[0086] The battery cells 14 contain at least one electrolyte based on sulfur dioxide (not shown here). In general, the invention is not further limited with respect to the battery cell 14 as long as the battery cell 14 comprises sulfur dioxide as the electrolyte.

[0087] For example, battery cells 14 can be used with an electrolyte composition from WO 2021 019 042 A1, WO 2015 045 73 A2 or the unpublished German patent application No. 10 2021 118 811.3.

[0088] The dosing device 32 comprises a storage container 18, which is arranged outside the storage housing 12.

[0089] The reservoir 18 contains a foaming additive 16.

[0090] The foaming additive 16 is present in an aqueous solution and comprises the following components: (A) At least one foaming agent selected from the group consisting of ionic surfactants, saponins and proteins, and combinations thereof; (B) At least one base selected from the group consisting of carbonates, hydrogen carbonates, oxides and hydroxides, and combinations thereof; and (C) Optionally, further additives selected from the group consisting of alkaline earth metal chlorides, flame retardants, higher alcohols and urea, and combinations thereof.

[0091] The reservoir 18 contains an amount of the foaming additive 16 sufficient to neutralize the sulfur dioxide contained in the battery cells 14. Preferably, the reservoir 18 contains an amount of the foaming additive 16 sufficient to completely neutralize the sulfur dioxide contained in at least one battery cell 14. Particularly preferably, the reservoir 18 contains an excess of the foaming additive 16 relative to the sulfur dioxide-based electrolyte contained in at least one of the battery cells 14. The latter is particularly advantageous because a residue typically remains in the reservoir 18 after its removal.

[0092] The storage tank 18 is fluidically connected via a line 20 to a feed pump 22, which is located outside the storage housing 12. The feed pump 22 is in turn connected to a proportioner 26, which is also located outside the storage housing.

[0093] The proportioner 26 is fluidly connected to a foam distributor 24, a circulation pump 28 and the delivery pump 22 via lines 20.

[0094] The foam distributor 24 is arranged in an interior space 33 of the storage housing 12. The foam distributor 24 can be designed as a rigid or a flexible conduit. Furthermore, the foam distributor 24 can be positioned anywhere within the storage housing 12. For example, the foam distributor 24 can be attached to an inner wall of the storage housing or fixed to an outer wall of a battery cell 14.

[0095] Furthermore, the foam distributor has 24 outlets (not shown here) for releasing the foam-forming additive 16. The outlets can, for example, be designed as nozzles that distribute the foam-forming additive 16 in the interior 33 of the storage housing 12. The release of the foam-forming additive 16 generates the foam 35 according to the invention for neutralizing the electrolyte. The foam 35 is formed, in particular, by a mixing of the foam-forming additive 16 with the atmosphere inside the storage housing 12. In particular, the gases released by escaping electrolyte contribute to the generation of the foam from the foam-forming additive 16.

[0096] Furthermore, an outlet opening 30 is embedded in a wall of the storage housing 12. The outlet opening 30 connects the interior 33 of the storage housing 12 to the circulation pump 28. The outlet opening 30 can be designed, for example, as a valve.

[0097] Furthermore, the safety device has a monitoring device 37.

[0098] The monitoring device 37 comprises a battery control system 36 and a sensor unit 38 connected to the battery control system 36, which is arranged inside the storage housing 12.

[0099] The sensor unit 38 can be positioned anywhere within the storage housing 12. It is therefore conceivable that the sensor unit 38 is fixed to an inner wall of the storage housing 12. However, the sensor unit 38 can also be attached directly to a battery cell 14.

[0100] In one embodiment of the invention, several sensor units 38 can also be arranged at any location within the storage housing 12. Thus, different areas of the battery storage 10 can be monitored by the sensor unit 38.

[0101] With regard to the sensor unit 38, the invention is not further limited. All sensor units commonly used in the prior art that are suitable for detecting a pressure, temperature, or atmospheric difference can be used.

[0102] Preferably, the sensor unit is a sensor for the selective detection of sulfur dioxide, preferably gaseous sulfur dioxide in an atmosphere. All sensors known in the prior art can be used for this purpose.

[0103] For example, an indicator known from US patent 4,222,745 A can be used to detect sulfur dioxide escaping from a battery. This indicator consists of potassium dichromate adsorbed onto finely divided silicon dioxide and an adhesive polymeric material, such as polydimethylsiloxane, as a stabilizing matrix. Titanium dioxide can also be added for intense color perception. Upon contact with sulfur dioxide, this indicator changes color.

[0104] Another conceivable detector is known from WO 02 079 746 A1, consisting of powdered potassium dichromate applied to an adhesive strip together with an oxidation accelerator and a metal oxide inhibitor, which enables the detection of, among other things, sulfur dioxide.

[0105] Also known is a sensor from US Patent 6,579,722 B1 for the detection of gaseous sulfur dioxide, in which a chemiluminescent reagent is immobilized in a polymer film. The chemiluminescence caused by contact with sulfur dioxide is detected using a photomultiplier or a photoelectric element.

[0106] Alternatively, a sensor from JP 2003035705 A can be used, which is suitable for the detection of sulfur dioxide in a gaseous sample, where the optical transmission in the UV / VIS / IR range is monitored under the influence of the analyte. The sensor consists of a combination of Orange-1 and amines, as well as a combination of iron ammonium sulfate, phenanthroline, and acids.

[0107] A sensor is also known from EP 0 585 212 A2, which is designed as a sensor membrane for the detection of sulfur dioxide. For this purpose, transition metal complexes with ruthenium, osmium, iridium, rhodium, palladium, platinum, or rhenium as the central atom, 2,2'-bipyridine, 1,10-phenanthroline, or 4,7-diphenyl-1,10-phenanthroline as ligands, and perchlorate, chloride, or sulfate as the counter-anion are used. The polymer matrix is ​​derived from the group of cellulose derivatives, polystyrenes, polytetrahydrofurans, or their derivatives.

[0108] Alternatively, a sensor from EP 0 578 630 A1 can be used, which provides a sensor membrane for optical sensors for the detection of sulfur dioxide. For this purpose, pH indicators, such as the fluorescent dye quinine or the absorption dye bromocresol purple, are immobilized with counterions, such as long-chain sulfonate ions or ammonium ions with long-chain residues, in a polymer matrix of polyvinyl chloride.

[0109] An optical sensor is particularly preferred for the selective detection of gaseous sulfur dioxide.

[0110] For example, an optical sensor, such as the one from the " Optical sensors for dissolved sulfur dioxide" (A. Stangelmayer, I. Klimant, OS Wolfbeis, Fresenius J. Analytical Chemistry, 1998, 362, 73-76) are known for their use in the detection of gaseous sulfur dioxide. Lipophilic pH indicators in the form of ion pairs immobilized in a gas-permeable silicone or OsmoSil membrane are used as sulfur dioxide sensors for gaseous samples. The pH indicators used are ditetraalkylammonium salts with long-chain alkyl groups of bromothymol blue, bromocresol purple, and bromophenol blue. The absorbance of light in the UV / VIS range serves as the measured parameter.

[0111] An optical sensor can also be used for the quantitative determination of sulfur dioxide in a sample, as known from DE 10 2004 051 924 A1. The sensor proposed here contains an indicator substance homogeneously immobilized in a matrix of the transparent sensor, which comes into at least indirect contact with the sample and changes its concentration in the presence of sulfur dioxide. This change in the concentration of the indicator substance can be monitored photometrically as a change in the light transmission in the UV / VIS range of the sensor.

[0112] In a particularly preferred embodiment, the sensor for the selective detection of sulfur dioxide is a sensor such as that used in the Figure 3 is described.

[0113] The sensor unit 38 is designed to detect any leakage of electrolyte from a battery cell 14, to generate data from this leakage, and to transmit it to the battery control system 36. The data is transmitted via an electrical connection 34.

[0114] The battery control system 36 is arranged outside the storage housing 12 and is electrically connected to the sensor unit 38 via connections 34. Preferably, the connections 34 are designed to transmit electrical signals and thus data.

[0115] The battery control system 36 is able to receive data from the sensor unit 38 and evaluate it with regard to a trigger or non-trigger scenario. If the battery control system registers abnormal data concerning a change in temperature, pressure, or atmosphere within the storage housing 12, the battery control system 36 triggers a trigger scenario.

[0116] The battery control system 36 is electrically connected to the pump 22 via a connection 34. In the event of a triggering scenario, the battery control system 36 can selectively control the pump 22, activating it and causing it to pump the foaming additive 16 out of the reservoir 18. The foaming additive 16 then travels from the reservoir 18 via the lines 20 and the pump 22 to the foam distributor 24, which finally releases the foaming additive 16 into the interior 33 of the storage housing 12, thus generating foam 35.

[0117] After a waiting period, the battery control system 36 can activate the circulation pump 28 via an electrical connection 34, so that the atmosphere of the interior 33 is extracted and returned to the interior 33 via lines 20, the proportioner 26 and the foam distributor 24. This circulates the atmosphere present in the interior 33 and brings any unneutralized electrolyte components back into contact with the foam 35.

[0118] Figure 2 shows the battery storage 10 from Figure 1 in the event of a trigger scenario.

[0119] Furthermore, the Figure 2 the same components as in Figure 1 already described.

[0120] The mechanism of a triggering scenario is described below using the following examples: Figure 2As described. If an electrical, thermal, or chemical defect occurs in a battery cell 14, the cell 14 may rupture. Such a battery cell 14 is therefore a defective cell 31. However, a cell 14 may also be damaged without rupturing. In both cases, a parameter inside the storage housing 12 will inevitably change, such as temperature, pressure, electrical properties of the cells, or atmospheric composition. A sensor unit 38 detects any change in these parameters.

[0121] In the event of a cell rupture of a defective cell 31, a sulfur dioxide-based electrolyte may leak out. The electrolyte can enter the interior 33 of the storage housing 12 in either liquid or gaseous form. The sensor unit 38 detects the presence of such an electrolyte in liquid or gaseous form within the storage housing by means of deviations in parameters, as described above. These deviations are transmitted as abnormal parameters in the form of data to the battery control system 36. The battery control system 36 continuously compares the received data with the expected data. If a predefined deviation of the received data from the expected data is detected, the battery control system 36 triggers a triggering scenario. Subsequently, the foaming additive 16 is extracted from the reservoir 18 by a pump 22 and fed to the foam distributor 24.The foam distributor 24 releases the foaming additive into the interior 33 of the storage housing 12. This release causes the electrolyte in the interior 33, the released foaming additive 16, and the atmosphere present in the storage housing 12 to mix. This results in the formation of a foam 35, which condenses in the interior 33. The foam 35 can both fix the electrolyte and neutralize it in an acid-base reaction.

[0122] Figure 3 shows a sulfur dioxide sensor based on a dual-beam spectrometer.

[0123] The gas sensor 39 has a detector chamber 44 enclosed by a detector housing 43. Furthermore, the detector housing 43 has a gas inlet opening 41.

[0124] The gas inlet opening 41 connects the detector chamber 44 to the interior 33 of the storage housing via a flow path. This allows free gas exchange between the two areas, and any electrolyte escaping from the storage housing 12 can be detected by the gas sensor 39.

[0125] The detector housing 43 has an elongated shape, with a light source 42 assigned to one end inside the housing.

[0126] The light source 42 is preferably an infrared light source, particularly preferably a near-infrared light source. The invention is not limited with respect to the infrared light source. All IR light sources known in the prior art can be used, as long as they can emit wavelengths suitable for detecting sulfur dioxide in a gas atmosphere.

[0127] Preferably, the light source 42 emits wavelengths in the range between 400 and 1800 cm⁻¹, particularly preferably between 450 and 600 cm⁻¹, 1100 and 1200 cm⁻¹ and / or 1300 and 1400 cm⁻¹. In operation, the light source 42 emits a NIR beam 46 with a continuous spectrum of wavelengths in the above-mentioned range.

[0128] The NIR beam 46 emitted by the light source 42 is split into two spatially separated NIR beams by a measuring beam aperture 48 and a reference beam aperture 50 located in the detector chamber 44. More precisely, the NIR beam 46 is split into a measuring beam 56 by the measuring beam aperture 48 and into a reference beam 58 by the reference beam aperture 50. Thus, the apertures create two separate beam paths.

[0129] The measuring beam 56 strikes a measuring beam filter 52 after passing through the measuring beam aperture 48. The reference beam 58 strikes a reference beam filter 54 after passing through the reference beam aperture 50.

[0130] Suitable measuring beam filters 52 and the reference beam filter 54 are, for example, bandpass filters, preferably narrowband filters. For example, the bandpass filters can have a bandwidth of 10 - 0.2 nm, preferably 5 - 0.2 nm, and particularly preferably 2 - 0.2 nm. These are thus able to selectively filter out a predetermined wavelength from the reference beam 58 and the measuring beam 56.

[0131] The transmission range of the reference beam filter 54 is chosen as a reference such that it is transparent in a narrow region of the spectrum in which neither sulfur dioxide nor other molecules, such as carbon dioxide, have absorption bands.

[0132] For the measuring beam filter 52, i.e., that of the measuring beam 56, the transmission range is chosen so that it falls into a range where only sulfur dioxide is absorbed, but no other gases that could distort the measurement signal.

[0133] Examples of suitable wavelengths for the measuring beam filter are: 1.56 µm, 1.57 µm, 1.58 µm, 2.46 µm and 4.02 µm.

[0134] After passing through the measuring beam filter 52, the measuring beam 56 strikes a measuring beam detector 62 located downstream of the measuring beam filter 52. Similarly, the reference beam 58 strikes a reference beam detector 60 located downstream of the reference beam filter 54.

[0135] For detecting the wavelengths transmitted by the filters, detectors based on thermocouples are suitable, for example. These are able to convert thermal energy directly into electrical energy, thereby generating and detecting very low thermoelectric voltages. Detectors used in this way are therefore particularly precise and suitable for detecting even small amounts of sulfur dioxide in an atmosphere.

[0136] Figure 4 shows a measuring range of a sulfur dioxide sensor made of Figure 3 , where absorption is plotted against a wavelength. The summed absorption of the measuring beam and the reference beam detector 60, 62 is shown.

[0137] The measuring beam detector 62 detects the measurement signal 64 in a measurement wavelength range 68, while the reference beam detector 60 detects the reference signal 66 in a reference wavelength range 70. The reference wavelength range 70 and the measurement wavelength range 68 are predetermined by the choice of beam filters. Likewise, the width of the measured wavelength ranges depends on the choice of beam filter and is typically 10 - 0.2 nm, preferably 5 - 0.2 nm, and particularly preferably 2 - 0.2 nm.

[0138] If the measuring beam detector 62 detects a measurement signal 64, sulfur dioxide is present in the atmosphere of the detector chamber 44 and thus also in the interior of the storage housing 12. A threshold value can be defined for a positive sulfur dioxide detection, which is typically above the background noise of the detector.

[0139] The advantage of the presented dual-beam spectrometers is their compact size, allowing them to be housed within the storage housing 12 in a space-saving manner. Furthermore, sulfur dioxide is detected spectroscopically, which simplifies the evaluation and conversion into electronic information compared to conventional methods.

[0140] Figure 5 shows a schematic flowchart of the steps of a procedure for triggering a safety device for a battery storage system described above.

[0141] The first step involves detecting any electrolyte leakage from a battery cell (step 1). This detection is performed by a sensor unit of the monitoring device located inside the battery housing. The sensor unit generates data and transmits it to the battery control system.

[0142] Subsequently, the battery control system evaluates the data to determine whether a trigger or non-trigger scenario has occurred (step 2). The battery control system evaluates the parameters measured by the sensor unit by comparing them with the expected parameters.

[0143] If a parameter deviation occurs and this deviation lies outside a tolerance range, a trigger scenario is executed (step 3). The tolerance range depends on various factors, such as the choice of detector or the design of the beam path, and is therefore selected according to the design of the battery storage system or the gas sensor.

[0144] The dosing device is then controlled by the battery control system activating a feed pump, and the feed pump extracts the foaming additive from the reservoir and feeds it to a foam distributor located inside the storage housing (step 4).

[0145] In the next step, the foam distributor creates a foam from the foam-forming additive by bringing the foam-forming additive into contact with the atmosphere inside the storage housing (step 5).

[0146] The generated foam is then released inside the storage housing (step 6).

[0147] Optionally, a waiting period can then be observed (step 7). This is particularly advantageous because the waiting period allows the foam and the released electrolyte a certain reaction time in which neutralization can take place.

[0148] After a waiting period, a circulation pump can optionally be activated (step 8). The circulation pump draws out the gas atmosphere present in the storage housing and returns it to the housing via the proportioner and the foam distributor. This circulates the gas atmosphere inside the housing. In this way, the escaping electrolyte, which has accumulated in the atmosphere inside the housing, can be efficiently brought into contact with the released foam. Preferably, the circulation pump remains in operation until the sensor unit no longer detects any electrolyte in the housing.

Claims

1. Battery storage device (10) with a storage housing (12) and at least one battery cell (14) which is arranged in an interior space (33) of the storage housing (12) and contains an electrolyte based on sulfur dioxide, characterized in that the battery storage device (10) has a safety device with a metering device (32) which comprises a foam-forming additive (16) and is configured to generate a foam (35) from the foam-forming additive (16) for neutralizing the electrolyte and to release the foam (35) in the interior space (33) of the storage housing (12), wherein during neutralizing of the electrolyte with the foam (35) constituents of the electrolyte are chemically neutralized.

2. Battery storage device (10) according to claim 1, characterized in that the foam-forming additive (16) is present in an aqueous solution and comprises the following components: a) at least one foaming agent selected from the group consisting of ionic surfactants, saponins and protein substances as well as combinations thereof, b) at least one base selected from the group consisting of carbonates, hydrogen carbonates, oxides and hydroxides as well as combinations thereof, and c) optionally further additives selected from the group consisting of alkaline earth metal chlorides, flame retardants, higher alcohols and urea as well as combinations thereof.

3. Battery storage device (10) according to any one of the preceding claims, characterized in that the metering device (32) has a storage container (18) containing the foam-forming additive (16) and a feed pump (22) connected to the storage container (18), wherein the feed pump (22) is connected to a foam distributor (24) arranged in the interior space (33) of the storage housing (12).

4. Battery storage device (10) according to claim 3, characterized in that the metering device (32) comprises a mixer (26) and a circulation pump (28), wherein the mixer (26) has in each case a separate connection to the foam distributor (24), the feed pump (22) and the circulation pump (28), and wherein the circulation pump (28) is connected in terms of flow to the interior space (33) of the storage housing (12).

5. Battery storage device (10) according to any one of the preceding claims, characterized in that the safety device has a monitoring device (37), wherein the monitoring device (37) comprises a battery control system (36) and a sensor unit (38) connected to the battery control system (36).

6. Battery storage device (10) according to claim 5, characterized in that the sensor unit (38) is selected from the group consisting of optical sensors, pressure, temperature and chemical sensors, more preferably that the sensor unit is a spectroscopic gas sensor (39) for detecting gaseous sulfur dioxide.

7. Battery storage device (10) according to claims 5 or 6, characterized in that the sensor unit (38) is configured to detect an escape of the electrolyte from a battery cell (14), to generate data therefrom and to forward it to the battery control system (36), wherein the battery control system (36) is provided to receive data from the sensor unit (38) and to evaluate it with regard to a triggering or non-triggering scenario.

8. Battery storage device (10) according to claim 7, characterized in that the battery control system (36) is further configured to control the metering device (32) when a triggering scenario is present, so that a foam (35) is generated from the foam-forming additive (16) and released in the interior space (33) of the storage housing (12).

9. Battery storage device (10) according to claim 8, characterized in that the battery control system (36) is further configured to control the metering device (32) for activating the circulation pump (28) when a triggering scenario is present, which suctions a gas atmosphere present in the storage housing, and returns it to the storage housing via the mixer and the foam distributor.

10. Method for triggering a safety device for a battery storage device (10) according to claim 8 or 9, characterized in that the method comprises the following steps: (a) detecting an escape of the electrolyte from a battery cell (14) in the interior space (33) of the storage housing (12) by the sensor unit (38) of the monitoring device (37), wherein data is generated therefrom and forwarded to the battery control system (36), (b) evaluating the data by the battery control system (36) with regard to the presence of a triggering or non-triggering scenario, (c) detecting a triggering scenario, (d) controlling the metering device (32), (e) generating a foam (35) from the foam-forming additive (16), (f) releasing the foam (35) in the interior space (33) of the storage housing (12), (g) optionally maintaining a waiting time, and (h) optionally activating a circulation pump (28) which suctions a gas atmosphere present in the interior space (33) of the storage housing (12) and returns it to the storage housing (12) via the mixer (26) and foam distributor (24).