BATTERY MODULE

Description

[0001] The invention relates to a battery module, in particular for lithium-based accumulators.

[0002] Lithium-based batteries are becoming increasingly attractive, for example, due to their high energy density. However, especially for large energy storage applications, there are two fundamental differences compared to lead-acid batteries. Firstly, the individual cells cannot simply be arbitrarily enlarged. This means that a large number of batteries are regularly combined to form a larger module. Secondly, these batteries are particularly susceptible to thermal runaway. Since this process also releases a large amount of gas, it poses a significant risk, especially in critical environments, as has been demonstrated with batteries in aircraft.

[0003] Therefore, suitable batteries, for example those used in submarines, are integrated into special modules that offer a high level of protection in the event of thermal runaway in a single battery. This prevents cascading runaway in neighboring batteries and ensures continued safety.

[0004] From DE 10 2019 216 606 A1 a battery module is known, wherein the second module housing part has at least one first gas channel, wherein the first gas channel connects at least the burst point of the second module housing part, which is located behind the first accumulator, and the burst point of the second module housing part, which is located behind the second accumulator, on the side opposite the cavities.

[0005] From DE 10 2019 216 608 A1, a battery module is known, wherein the battery module has at least one first accumulator and one second accumulator, wherein all accumulators have at least two electrical contacts, wherein all accumulators have a burst membrane, wherein all burst membranes are arranged in the same direction, wherein all accumulators are arranged in a module housing, wherein at least one first sensor is arranged in the direction of action behind the burst membrane of the accumulators, wherein the first sensor is designed to detect pressure, temperature or a chemical substance.

[0006] While these modules can prevent a chain reaction in the event of a thermal runaway of a single battery, they cannot prevent the gases produced. Since a significantly larger number of batteries are required compared to lead-acid batteries, and manufacturing tolerances must always be assumed, it is difficult to guarantee absolute certainty that none of the batteries will experience a thermal runaway. However, for use, particularly in a submarine, it is desirable to avoid hazardous gases to reduce the risk to the crew, even if a single battery experiences a thermal runaway.

[0007] A gas purification unit for a lithium cell is known from DE 10 2014 212 173 A1.

[0008] A housing for an electrochemical cell is known from US 2021 / 0 135 314 A1.

[0009] An energy storage system is known from KR 10 2 251 413 B1.

[0010] From DE 10 2012 222 870 A1 an energy storage device with a safety valve is known.

[0011] From DE 10 2021 130 696 A1 a battery outgassing filter system and a method for filtering outgassing from a battery cell is known.

[0012] The object of the invention is to create a battery module that prevents the release of dangerous gases to the crew in the event of thermal runaway of a battery.

[0013] This problem is solved by the battery module with the features specified in claim 1. Advantageous further developments are described in the dependent claims, the following description, and the drawings.

[0014] The battery module according to the invention comprises a plurality of accumulators. The battery module has a gas channel. The gas channel has an outlet. A catalyst is arranged at the outlet of the gas channel. The arrangement at the outlet ensures that, in addition to the gas from the thermal runaway of an accumulator, atmospheric oxygen is also present, with which the hazardous gases, for example and in particular carbon monoxide and hydrogen, can be converted to carbon dioxide and water, and thus to harmless compounds.

[0015] To achieve optimal catalyst reaction, a controlled supply of ambient air to the gas flowing through the catalyst is beneficial, ensuring sufficient oxygen for the reaction to occur. The challenge here is that a catalyst can become permanently exposed to ambient air, for example, and particularly in a submarine, where it can be covered by oily substances and thus lose its activity. Therefore, it is necessary to supply the catalyst with air in the event of a battery failure, while simultaneously protecting it from contamination during normal operation. To ensure an adequate oxygen supply, the gas channel upstream of the catalyst has at least one initial air inlet. However, to protect the catalyst during normal operation, this initial air inlet is equipped with a shut-off element.This ensures that the first air inlet is closed during normal operation, thus protecting the catalyst from contamination. The closure element is held in a position that closes the first air inlet by a retaining element. When the retaining element is removed, the closure element can, for example, fold away, fall off, or be detached from the first air inlet in some other way, such as by a pre-tensioned spring element. The retaining element incorporates a melting element. The melting element of the retaining element is located inside the catalyst.

[0016] The effect is that the initial gases react with the oxygen present in the gas channel at the catalyst, causing an initial reaction and thus an initial release of heat. This heat is used to melt the melting element, so that the retaining element no longer holds the sealing element in position. This releases the initial air supply, allowing ambient air to be introduced into the gas stream leading to the catalyst, thus ensuring a safe reaction of the harmful gases at the catalyst.

[0017] The battery module can have any design. Preferably, the battery module according to DE 10 2019 216 606 A1 or DE 10 2019 216 608 A1 is incorporated in its entirety into this disclosure for the design of the battery module.

[0018] In particular, the battery module is suitable for use in a submarine. A submarine has a very limited surrounding atmosphere, which is also needed by the crew. Therefore, safety is of paramount importance for its use on board a submarine.

[0019] For example, and preferably, the battery module comprises at least one first accumulator and one second accumulator. Preferably, the battery module comprises 20 to 500, and more preferably 50 to 200, accumulators. All accumulators have a cylindrical shape. This means that the individual accumulators are not designed as pouch cells, which can typically compensate for larger volume changes. Cylindrical accumulators, on the other hand, can be easily manufactured and connected in large numbers to form a module. All accumulators have at least two electrical contacts, preferably exactly two, one for the anode and one for the cathode. All accumulators have at least one electrical contact on a first cylindrical end face. For example, the other electrical contact can be made via the outer surface. Furthermore, all accumulators have a rupture diaphragm on a second cylindrical end face.

[0020] In the battery module, all accumulators are arranged, preferably in parallel to each other, with all first cylindrical end faces facing in the same direction. This allows the electrical energy to be dissipated centrally on one side. All accumulators are housed in a module casing.

[0021] The module housing preferably comprises a first module housing part and a second module housing part. The first module housing part is flat and arranged perpendicular to the longitudinal direction of the accumulators. The second module housing part is also flat and arranged perpendicular to the longitudinal direction of the accumulators.

[0022] The first module housing part has, for example, and preferably, first recesses for receiving one portion of the accumulators in the area of ​​the first cylindrical end faces. The first module housing part has openings in the area of ​​the first recesses for the electrical connections. This is necessary to electrically contact the accumulators and dissipate the power. The second module housing part has second recesses for receiving one portion of the accumulators in the area of ​​the second cylindrical end faces.

[0023] For example, and preferably, a potting compound is arranged between the first module housing part, the second module housing part and the accumulators.

[0024] The second module housing part has, for example, and preferably, burst points in the area of ​​the second recesses. A cavity is arranged between the burst points of the second module housing part and the burst membranes of the second cylinder end faces. The cavity can, for example, and preferably, be gas-filled, in particular air-filled, or inert gas-filled, in particular nitrogen or argon-filled.

[0025] Due to the arrangement of all batteries within the module housing, they are all protected from the environment. If a battery experiences thermal runaway, it produces large quantities of hot gases, which, upon direct contact, can easily cause neighboring batteries to also become critical and experience thermal runaway. However, since the batteries are protected within the module housing, a single runaway battery cannot cause neighboring batteries to also experience thermal runaway. Simply installing the battery completely would prevent the resulting pressure from being released. If a single battery experiences thermal runaway, pressure builds up inside the battery, causing the rupture diaphragm on the second end face of the cylinder to burst. This increases the pressure in the cavity adjacent to the battery.This pressure increase causes the burst point in the area of ​​the second recesses of the second module housing part to also burst, so that the resulting gases are released to the outside and the pressure is reduced without causing further damage.

[0026] For example, and preferably, the second module housing part has at least one first gas channel, wherein the first gas channel connects at least the rupture point of the second module housing part located behind the first accumulator and the rupture point of the second module housing part located behind the second accumulator on the side opposite the cavities. Gases generated during thermal runaway or other exothermic chemical reactions of an accumulator can thus be selectively vented through the first gas channel, for example, upwards. This is particularly preferred when several battery modules are to be installed side by side, so that the generated gases do not come into contact with the electrical contacts of another battery module, as this could damage them.

[0027] In a further embodiment of the invention, the gas channel has a tapered cross-section in the region of the catalyst. This increases the flow velocity, which in turn leads to a lower pressure due to the Bernoulli effect and thus to the intake of ambient air. Furthermore, the higher flow velocity due to the Venturi effect results in a more turbulent flow, leading to better mixing.

[0028] In a further embodiment of the invention, the sealing element is arranged in a sleeve-like form around the gas channel. Particularly preferably, the sealing element has two longitudinal slots and assumes a V-shaped form in the relaxed state, as is the case, for example, with a dowel which, in its delivered state, is held together by a contact at the tip. The contact breaks when the screw is first tightened, and the wings of the dowel bend outwards. This eliminates the need for additional elements, such as a spring element arranged beneath the sealing element.

[0029] In a further embodiment of the invention, the melting element consists of an elastomer, for example polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polyamide, or polyoxymethylene. A low melting point and a low enthalpy of fusion (or low glass transition temperature) are advantageous here, so polymers with short or medium chain lengths and minimal branching are particularly suitable. For example, a PE with a melting point of 10,000 Daltons and a crystallinity of 50% can be used.

[0030] In a further embodiment of the invention, the catalyst contains platinum. Platinum is particularly well suited for the catalytic ignition of hydrogen. Carbon monoxide also reacts readily with platinum. However, it is not necessary for the entire hazardous gas to be reacted at the catalyst. It may be sufficient for a reaction at the catalyst to generate heat or a flame in which the hazardous gases can then burn off into at least less hazardous or harmless products.

[0031] In a further embodiment of the invention, the catalyst is designed as a grid or mesh. The gases can thus flow very easily out of the gas channel and through the grid or mesh, mixing with atmospheric oxygen and reacting within this structure. The grid can be a plastic or metal grid coated with the catalyst, or the grid can consist of the catalyst itself.

[0032] In a further embodiment of the invention, the gas channel at the outlet is provided with a rupture membrane. The rupture membrane is coated with the catalyst on the side facing the gas channel. This provides excellent protection for the catalyst against aging and fouling during normal operation. Furthermore, a rupture membrane made of a plastic film can be coated with an extremely thin layer of, for example, platinum, which in turn reduces the amount of precious metal required and thus the costs. Since only an initial ignition at the catalyst is necessary, this small amount of catalyst in the coating is sufficient.

[0033] In a further embodiment of the invention, the catalyst borders the gas channel only on one side. This means that the catalyst is exposed to the ambient air on all other sides, which improves mixing with atmospheric oxygen and thus leads to a stable conversion of the hazardous gases. For example, the catalyst can have a wire-sponge-like structure.

[0034] With a battery module according to the invention, for example, a method for converting hazardous gases from a thermal runaway of a battery can be carried out. The gases are first guided from the thermally runaway battery through a gas channel. This directs the hot gases away from the other batteries in the battery module, thus making thermal runaway of further batteries less likely. In the region of the gas channel outlet, the gas is mixed with ambient air and converted in the presence of a catalyst.

[0035] This prevents dangerous gases from being released into the environment; in particular, the main components carbon monoxide and hydrogen are reliably converted into carbon dioxide and water.

[0036] The battery module according to the invention is explained in more detail below with reference to an embodiment shown in the drawings. Fig. 1 Module Fig. 2 First embodiment Fig. 3 Second embodiment Fig. 4 Third embodiment Fig. 5 Fourth embodiment before triggering Fig. 6 Fourth embodiment after triggering

[0037] Fig. 1 shows an overview of battery module 10. Fig. 2 bis Fig. 4 Three exemplary embodiments are then shown showing how the outlet of the gas channel 3.0 can be provided with a catalyst 40 according to the invention.

[0038] In Fig. 1 The battery module 10 is shown in a simplified cross-section. In the illustrated case, the battery module has four accumulators; typically, the number is significantly higher. The accumulators are arranged so that they are connected to gas channel 30 in the event of thermal runaway. This ensures that the hot gases are quickly and safely vented. The battery module 10 can be designed in accordance with DE 10 2019 216 606 A1 or DE 10 2019 216 608 A1. A new feature is the arrangement of a catalyst 40 at the outlet of gas channel 30 to convert the hazardous gases, for example, and in particular, carbon monoxide and hydrogen, especially by combusting them with atmospheric oxygen. Carbon monoxide is converted to carbon dioxide, and hydrogen to water.

[0039] The following are three exemplary embodiments for the arrangement of the catalyst 40 at the outlet of the gas channel 30.

[0040] Fig. 2 consists of Fig. 2 a und Fig. 2 b. Fig. 2 a shows a side cross-section, Fig. 2 b a supervisor. In this first embodiment, the catalyst 40 is designed as a platinum mesh at the outlet of the gas channel 30. The advantage is that it seals cleanly with the battery module 10 and itself forms only a low flow resistance, so that the hot exiting gases are not retained and cannot overheat further accumulators 20.

[0041] In Fig. 3 A further exemplary second embodiment is shown. The catalyst 40 is designed as a wire cage or as wire wool. Additional ambient air is drawn in from the side by the escaping gas, resulting in better mixing between the ambient air and the escaping gases in the area of ​​the catalyst 40. This increases ignition reliability and promotes reaction at the catalyst 40. A disadvantage is that the catalyst 40 protrudes above the surface of the battery module 10 as a result.

[0042] Fig. 4 consists of Fig. 4 a und Fig. 4 b. Fig. 4 A third exemplary embodiment with a Bestmembrane 50 is shown. Fig. 4 a is shown closed in its normal state, in Fig. 4 b The rupture membrane 50 opens after the thermal runaway of an accumulator 20. The rupture membrane 50 is, for example, a thin plastic film, such as polyethylene, polypropylene, or polytetrafluoroethylene. The rupture membrane 50 is coated on the side facing the gas channel 30 with a catalyst layer, for example, with platinum vapor deposition. Such layers can be extremely thin, thus saving material. In the event of thermal runaway, the rupture membrane 50 ruptures, and the hazardous gases come into contact with atmospheric oxygen and the catalyst 40. The advantage of this embodiment is that the catalyst 40 is not exposed to the environment during normal operation and therefore cannot be covered by dust, for example. Thus, the catalyst's operational capability is ensured in an emergency.

[0043] In Fig. 5 und Fig. 6 A fourth embodiment is shown. Fig. 5 This is shown in normal operation and Fig. 6 after triggering following a thermal runaway. The gas channel 30 has air inlets 60 located below the catalyst 40. Under normal conditions, as in Fig. 5 As shown, the air inlets 60 are closed by the closure element 70. This is achieved by a retaining element consisting of a melting element 80 and two clamping elements 90. If a thermal runaway occurs, the gases mix with the air in the gas channel 30, resulting in a small initial reaction of this gas mixture at the catalyst 40, causing a temperature increase that melts the melting element 80. This causes the closure element 70 to spring into its relaxed state, as shown in Fig. 6This is shown. This opens the air inlets 60, allowing air to be drawn in. This is improved by the narrowing of the gas channel 30. The narrowing causes an increase in flow velocity due to the Venturi effect, which promotes better mixing, and a pressure reduction due to the Bernoulli effect, causing ambient air to be drawn in. Reference sign

[0044] 10 Battery module 20 Accumulator 30 Gas channel 40 Catalyst 50 Burst membrane 60 Air supply 70 Sealing element 80 Fusing element 90 Tensioning element

Claims

1. Battery module (10), wherein the battery module (10) has a plurality of accumulators (20), wherein the battery module (10) has a gas channel (30), wherein the gas channel (30) has an outlet, characterised in that a catalytic converter (40) is arranged at the outlet of the gas channel, wherein the gas channel (30) has at least one first air supply (60) upstream of the catalytic converter (40), wherein the first air supply (60) has a closure element (70), wherein the closure element (70) is held by a holding element in a position closing the first air supply (60), wherein the holding element has a melting element (80), wherein the melting element (80) of the holding element is arranged inside the catalytic converter (40).

2. Battery module (10) according to claim 1, characterised in that the gas channel (30) has a tapered cross-section in the region of the catalytic converter (40).

3. Battery module (10) according to one of the preceding claims, characterised in that the closure element (70) is arranged in the form of a sleeve around the gas channel (30).

4. Battery module (10) according to one of the preceding claims, characterised in that the melting element (80) consists of an elastomer.

5. Battery module (10) according to one of the preceding claims, characterised in that the catalyst (40) contains platinum.

6. Battery module (10) according to one of the preceding claims, characterised in that the catalytic converter (40) is designed as a grid or net.

7. Battery module (10) according to one of the preceding claims, characterised in that the gas channel (30) is provided with a bursting membrane (50) at the outlet, the bursting membrane (50) being coated with the catalyst (40) on the side facing the gas channel (30).

8. Battery module (10) according to one of the preceding claims, characterised in that the catalytic converter (40) is only adjacent to the gas channel (30) on one side.