A battery module

Abstract

According to the present invention there is provided a battery module (1) comprising, a chamber (2); a plurality of battery cells (3) arranged within said chamber (2); a liquid (5) which is located within the chamber (2), and which can change phase to a gas when heated above a predefined temperature; a sensor assembly (6) which is configured to detect changes in pressure within the chamber (2) caused by the change in phase of the liquid (5) to a gas. There is further provided an electric or hybrid vehicle comprising said battery module.

Description

A Battery ModuleField of the Invention

[0001] The present disclosure is related to a battery module for use in powering electric vehicles, such as electric or hybrid aircrafts.Background to the Invention

[0002] Electric and hybrid vehicles have become increasingly significant for the transportation of people and goods. Such vehicles can desirably provide energy efficiency advantages over combustion-powered vehicles and may cause less air pollution than combustion-powered vehicles during operation.

[0003] Although the technology for electric and hybrid automobiles has significantly developed in recent years, many of the innovations that enabled a transition from combustion-powered to electric-powered automobiles unfortunately do not directly apply to the development of electric or hybrid aircraft. The functionality of automobiles and the functionality of aircraft are sufficiently different in many aspects so that many of the design elements for electric and hybrid aircraft must be uniquely developed separate from those of electric and hybrid automobiles.

[0004] Moreover, any changes to an aircraft's design, such as to enable electric or hybrid operation, also require careful development and testing to ensure safety and reliability. If an aircraft experiences a serious failure during flight, the potential loss and safety risk from the failure may be very high as the failure could cause a crash of the aircraft and pose a safety or property damage risk to passengers or cargo, as well as individuals or property on the ground. i

[0005] The certification standards for electric or hybrid aircraft are further extremely stringent because of the risks posed by new aircraft designs. Designers of aircraft have struggled to find ways to meet the certification standards and bring new electric or hybrid aircraft designs to market.

[0006] Battery modules typically comprise a plurality of battery cell. Overheating of one or more of the battery cells in a battery module can lead to thermal runaway. Thermal runaway in refers to a self-perpetuating and uncontrollable chain reaction of increasing heat generation within the battery cells of battery module. Thermal runaway is a significant safety concern, in electric or hybrid vehicles, aerospace, and energy storage systems, where large battery modules are used. Thermal runaway is a dangerous and potentially catastrophic phenomenon that can lead to the release of excessive heat, smoke, gas, and even fire or explosion of the battery cells within a battery module. Hence the early detection and elimination of thermal runaway is a key challenge.

[0007] Early detection of overheating of a battery cell is particularly critical in the case of electric or hybrid aircrafts as flight safety is compromised if thermal runaway occurs; thermal runaway can endanger the structural integrity of the aircraft's battery modules and their ability to power the electric motor of the aircraft are compromised, potentially leading to a catastrophic failure.

[0008] Existing techniques to detect overheating of battery cells in battery modules of electric or hybrid aircrafts involve providing a temperature sensor on each battery cell of the battery module to measure the temperature of each battery cell. When a temperature sensor senses that the temperature of a battery module has increased above a predefined threshold temperature then the battery module is usually shut down to prevent thermal runaway from occurring. Disadvantages of these existing techniques include that a battery module for an electric or hybrid aircraft may have hundreds of battery modules, consequently,corresponding hundreds of temperature sensors need to be provided. Moreover, with so many temperature sensors the probability that a temperature sensor fails increases. Furthermore, each of these temperature sensors require electrical connection; the wires used to electrical connect the temperature sensors add weight to the battery module. Accordingly, existing techniques to detect overheating of battery cells in battery modules are disadvantageously expensive, complex, lack robustness, and add weight to the battery module.

[0009] It is an aim of the present invention to mitigate, or obviate, at least some of the disadvantages associated with existing techniques used to detect overheating in the battery cells of a battery modules, in particular in battery modules of electric or hybrid aircrafts.Summary of the Invention

[0010] According to the present invention there is provided a battery module having the features recited in independent claim 1.

[0011] In the present invention if any one or more battery cells in the battery module overheat, or catch fire, the heat generated will cause at least some of the liquid within the chamber to change phase from a liquid to a gas. This change in phase of the liquid to gas within the chamber will increase the pressure within the chamber. The increase in pressure within the chamber will be detected by the sensor assembly; thus, the detection of increased pressure by the sensor assembly can be used to detect if any one or more battery cells overheat or catch fire. Advantageously, the present invention enables the detection of overheating, or fire, in any battery cells of the battery module, without having to provide respective dedicated temperature sensors for each respective battery cell; accordingly, the battery module has less electrical components, and less electrical wiring, this leads to a more robust and lighter battery module. Furthermore, battery cells may be added to the battery module, without needing to adapt the sensor assembly - in other words the present invention enablesthe detection of overheating, or fire, in a battery cell, regardless of the number of battery cells that are provided in the battery module.

[0012] The dependent claims recite optional features of various embodiments of the invention.

[0013] It should be understood that on the features recited in claim 1 are essential to the present invention; any subsequently described features may be optional features of any of embodiments described in the present disclosure. Even if a feature is described in the present disclosure as being a feature of an embodiment, it should be understood that that feature could be an optional feature of any of the other embodiments of the present invention. Any embodiment disclosed in the present disclosure may have any one or more of the features of any of the other embodiments disclosed in the present disclosure.

[0014] According to a further aspect of the present invention there is provided an electric or hybrid vehicle comprising a battery module according to any embodiment of the present invention.Brief Description of the Drawings

[0015] Exemplary embodiments of the present invention are disclosed in the description and illustrated by the drawings in which:Figure 1 illustrates a battery module according to an embodiment of the present invention;Figure 2a illustrates the battery module of Figure 1 in use, and specifically illustrates the detection of liquid leaking from the chamber of the battery module;Figure 2b illustrates the battery module of Figure 1 in use, and specifically illustrates the detection of a battery cell in the battery module, overheating or on fire;Figure 3 illustrates a battery module according to a further embodiment of the present invention;Figure 4 illustrates a battery module according to a further embodiment of the present invention;Figures 5a and 5b illustrate a battery module according to a further embodiment of the present invention; Figure 5a illustrates the battery module when the pressure inside the chamber is below a predefined threshold pressure; and Figure 5b illustrates the battery module when the pressure inside the chamber is equal to, or above, the predefined threshold pressure.Detrained Description of Exemplary Embodiments of the Invention

[0016] Figure 1 illustrates a battery module 1 according to a first embodiment of the present invention. The battery module 1 comprises a chamber 2; a plurality of battery cells 3 arranged within said chamber 2; a liquid 5 which is located within the chamber 2, and which can change phase to a gas when heated above a predefined temperature; and a sensor assembly 6 which is configured to detect changes in pressure within the chamber 1 caused by the change in phase of the liquid 5 to a gas.

[0017] In the present embodiment the chamber 2 is air-tight, or is selectively configurable to be air-tight. In an embodiment the chamber 2 has a door which can be selectively opened to allow access to the inside of the chamber, and can be selectively closed to hermetically seal the chamber 2.

[0018] In this embodiment the plurality of battery cells are arranged in parallel within the chamber 2. Each battery cell has a positive electric pole 3a located at a first end of the battery cell 3, and a negative electric pole 3b located at a second, opposite, end of the battery cell 3. In the exemplary embodiment of the battery module 1 shown in Figure 1, the plurality of battery cells are arranged within the chamber 2 so that the negative electric pole 3b of each respective battery cell 3 is facing in a direction which is towards the liquid 5. It should be understood that the battery cells may be arranged differently without any impact on the scope of the invention. It should be understood that the plurality of battery cells may be arranged in any suitable orientation within the chamber 2. For example, the battery cells may not be arranged in parallel, or they may not be all oriented with the negative electric pole towards the liquid.

[0019] It should be understood that the battery cells 3 may take any suitable form. In the battery module 1 example shown in Figure 1, each battery cell 3 is cylindrical. In another embodiment the battery cells 3 may have a pouch or prismatic form. In the present embodiment each of the plurality of battery cells 3 comprise lithium-ion battery cells. However, it should be understood that the battery cells 3 may be of any type; for example, in another embodiment the plurality of battery cells 3 may comprise Lithium-Polymer battery cells, solid-state or quasi-solid-state battery cells.

[0020] In the present embodiment each of the battery cells 3 are held within a respective sleeve 8. However, it should be understood that the sleeves 8 are an optional feature.

[0021] Preferably, the liquid 5 is in thermally communication with the plurality of the battery cells 3 so that thermal energy can pass from the plurality of the battery cells 3 into the liquid 5. In this way the liquid 5 can provide cooling to the plurality of the battery cells 3 as the liquid will absorb heat generated by the plurality of the battery cells 3 up to a certain temperature. Not only will the liquid 5 absorb some or all heat generatedby the plurality of the battery cells 3, but if one or more of the battery cells catch fire the liquid 5 may also be capable of absorbing some, or all of the heat generated by that fire.

[0022] In the present embodiment each of the battery cells 3 are at least partially submerged in the liquid 5. Each of the battery cells 3 are held within a respective sleeve 8; and the sleeve may be positioned above the surface 35 of the liquid 5 or at least partially submerged in the liquid (i.e. a portion of the length of each respective sleeve 8 is submerged in the liquid 5; the submerged portion of each respective sleeve 8 is in direct contact with the liquid 5). Each of the sleeves 8 preferably comprise thermally conductive material this facilitates the conduction of heat away from the battery cells 3 and into liquid 5 via the sleeves 8. The sleeves 8 may comprise any suitable material; for example, each of the sleeves 8 may comprise any one or more of aluminum, stainless steel, carbon fiber reinforced polymer, aramide fiber, ultra high-molecular-weight polyethylene fiber, glass fiber . It should be understood that the sleeves 8 are optional features of the present invention. In another embodiment wherein the battery module 1 with without sleeves 8 for holding the respective battery cells 3, a portion of the length of each battery cell 3 is submerged in the liquid 5; the submerged portion of the battery cell 3 is in direct contact with the liquid 5. However, it should be understood that the plurality of the battery cells 3, or respective sleeves 8 in which the battery cells 3 are held, do not need to be in direct physical contact with the liquid 5 in order to for the liquid 5 to be thermally connected to the plurality of the battery cells 3; for example, the plurality of the battery cells 3, or respective sleeves 8 in which the battery cells 3 are held, may be located above the surface 35 of the liquid 5, but close enough to allow heat transfer from the plurality of the battery cells 3 to the liquid 5 by convection.

[0023] The liquid 5 may take any suitable form. In the battery module 1 shown in Figure 1 the liquid 5 is configured to change phase from a liquid to gas at a temperature between 50 °C -150°C. More preferably the liquid 5 changes phase from a liquid to gas at a temperature between 50 °C -100°C.Most preferably the liquid 5 changes phase from a liquid to gas at a temperature between 50 °C -80°C. It should be understood that the liquid may take any suitable form or may have any suitable composition. In the battery module shown in Figure 1 the liquid 5 comprises a dielectric and / or comprises a thermally conductive fluid. In an embodiment the liquid 5 comprises a perfluoropolyether fluorinated fluid. In an embodiment the liquid 5 may comprise any other suitable fluids having the appropriate dielectric and thermal properties.

[0024] The liquid 5 may be in the form of a mixture of a liquid solvent and solid. In an embodiment the liquid comprises a plurality of different phase change materials; for example, in an embodiment the liquid, which itself is a phase change material, may further comprise a second phasechange material, suspended / mixed in the liquid, and which has a composition which is different to the composition of the liquid. For example, in an embodiment the liquid which itself is a phase change material, may further comprise solid phase-change material mixed in / suspended in the liquid. Said solid phase-change material may change phase from a solid to a liquid at a temperature which is inferior to the temperature at which the liquid changes phase from a liquid to a gas. In other words, the temperature at which the solid material changes phase from a solid to a liquid may be higher than the temperature at which the liquid material changes phase from a liquid to a gas. In an embodiment the solid material may be configured to undergo two phase changes: a first phase change from a solid to a liquid at a first temperature, and then a second phase change from a liquid to a gas at a second temperature (preferably the second temperature is higher than the first temperature). A solid material that is configured to undergo two phase changes may absorb more heat energy than a solid which is configured to undergo just a single phase change from solid to a liquid. In yet another example the liquid may comprise a first liquid having a first composition and a second liquid having a second composition, wherein the temperature at which the second liquid changes phase from a liquid to a gas may be higher than the temperature at which the first liquid material changes phase from a liquid to a gas.

[0025] In an embodiment the battery module 1 may further comprise a thermally conductive material which is positioned between the plurality of battery cells 3 / sleeves 8, and the liquid 5, so as to facilitate the transfer of thermal energy from the plurality of battery cells 3 / sleeves 8 to the liquid 5.

[0026] Referring to Figure 1 it can be seen that the battery module 1 further comprises a duct 9 which is fluidly connected to the chamber 2. At least some of the liquid 5 is located in the duct 9. In this example the duct 9 is fluidly connected to the chamber 2 below the surface 35 of the liquid; as a result least some of the liquid 5 is located in the duct 9. In the example shown in Figure 1, at the junction where duct 9 connects to the chamber 2, the entire cross-sectional area of the duct 9 is submerged in the liquid 5. However, it should be understood that it is not essential that the entire cross-sectional area of the duct 9 be submerged in the liquid 5, at the junction where duct 9 connects to the chamber 2; in another example, at the junction where the duct 9 connects to the chamber 2, only a part of the cross-sectional area of the duct 9 is submerged in the liquid 5 while another part of the cross-sectional area of the duct 9 is above the surface of the liquid 5. In an example the level of the liquid 5 in the chamber 5 may be less than the diameter of the duct 9, in that case, at the junction where the duct 9 connects to the chamber 2, only a part of the cross-sectional area of the duct 9 would be submerged in the liquid 5. In another example the junction at which the duct 9 connects to the chamber 2 is located above the inside bottom surface of the chamber, so that at the junction part of the cross-sectional area of the duct 9 is located below the surface of the liquid 5 in the chamber 2 and another part of the cross-sectional area of the duct 9 is located above the surface of the liquid 5 in the chamber 2. It can be preferable to have only a part of the cross-sectional area of the duct 9 submerged in the liquid 5 at the junction where the duct 9 connects to the chamber 2, because gas, fumes, smoke, etc, can more easily pass from the chamber 2 into the duct 9 via the other part of cross-sectional area of the duct 9 which is not submerged in the liquid 5.

[0027] The battery module 1 further comprises a sensor assembly 6 which is configured to detect changes in pressure within the chamber 2 caused by the change in phase of the liquid 5 to a gas.

[0028] In the exemplary battery module 1 the sensor assembly 6 comprises, a spring member 15 which has a first end 15a which is fixed and a second opposite end 15b which is a free end. A stopper member 16 is attached to the free end 15b of the spring member 15 and is located within the duct 9. The stopper member 16 blocks the flow of liquid 5 through the duct 9. In a preferred embodiment the spring member 15 biases the stopper member 16 against the liquid 5 in the duct 9.

[0029] It should be understood that the spring member 15 may take any form. The spring member 15 may be any member which is elastically compressible. For example, the spring member 15 may comprise, a spring coil, or a flexible diaphragm, an elastically compressible block member (such as a rubber bock member or a foam block member). In the battery module 1 embodiment shown in Figure 1 the spring member 15 comprises a spring coil 15.

[0030] It should also be understood that while stopper member 16 is shown in the battery module 1 to be attached to the free end 15b of the spring member 15, in another embodiment the stopper member 16 could be integral to the spring member 15. For example, the spring member 15 may comprise a flexible diaphragm and the stopper member 16 may be a surface of the flexible diaphragm; or, in another example, the spring member 15 may comprise an elastically compressible block member (such as a rubber bock member or a foam block member) and the stopper member 16 may be a surface of that elastically compressible block member.

[0031] The sensor assembly 6 further comprises a first contact member 20a which is located along the duct 9. The first contact member 20a is configured to send a first signal to a controller when a stopper member 16 reaches a first predefined trigger position along the duct 9. The controlleris preferably part of a Battery Management System (BMS) which is responsible for monitoring, managing, and protecting a battery pack which comprises one or more of said battery modules 1 of the present invention.

[0032] The first contact member 20a may take any suitable form; for example, the first contact member 20a may be in the form of a mechanical latch, or the first contact member 20a may be in the form of an electrical contact, or the first contact member 20a may be in any other suitable form . In the present invention the first contact 20a is in the form of a first mechanical latch 20a.

[0033] In the present embodiment the first predefined trigger position corresponds to the position of the first mechanical latch 20a along the duct 9. When the stopper member 16 reaches the first mechanical latch 20a the stopper member 16 engages (preferably mechanically engages) the first mechanical latch 20a to trigger / initiate the first mechanical latch 20a to send the first signal to the controller.

[0034] The first signal will indicate that one of the battery cells 3 is overheating or has caught fire. Preferably, the controller is configured to shut down the battery module 1 in response to receiving a first signal from first mechanical latch 20a.

[0035] In this embodiment the battery module 1 further comprises a plurality of temperature sensors 17. A respective temperature sensor 17 is provided for each respective battery cell 3. Specifically, in the battery module 1, a respective temperature sensor 17 is attached to a respective battery cell 3 (preferably each respective temperature sensor 17 is attached proximate to the positive pole 3a of the respective battery cells 3). Each respective temperature sensor 17 is configured to measure the temperature of the battery cell 3 to which it is attached. Each respective temperature sensor 17 is operably connected to the controller, which is preferably part of the Battery Management System (BMS). In this embodiment each respective temperature sensor 17 is operably connected to the controllervia an electrical bus line 17b. Each temperature sensor 17 is configured to send an alert signal to the controller, in response to sensing that the temperature of the battery cell 3 to which it is attached exceeds a predefined threshold temperature. Preferably, in response to receiving an alert signal the controller will shut down the battery module 1. However, it should be understood that the temperatures sensors 17 are not an essential feature of the present invention; indeed, an advantage of the present invention is that it eliminates the need for having dedicated respective temperature sensors 17 for each respective battery cell 3 in order to detect if any one of the battery cells 3 overheat or catch fire.

[0036] The spring member 15 is partially compressed by force applied by the liquid 5 in the duct 9 to the stopper member 16. This ensures that the spring member 15 is initially in a partially compressed state. The force applied by the liquid 5 in the duct 9 to the stopper member 16 results from pressure within the chamber 2 and / or pressure applied by the liquid 5 in the chamber 2 to the volume of liquid in the duct 9. The stiffness of the spring member 15 is such that the spring member 15 will partially compress, by force applied by the liquid 5 in the duct 9 to the stopper member 16, when there is a nominal pressure, which is preferably atmospheric pressure, is inside the chamber 2. Thus, the spring member 15 will be in an initial partially compressed state. Preferably, the nominal pressure is between 1.1- 2.3 bar; most preferably the nominal pressure is 2 bar.

[0037] As pressure within the chamber 2 increases (from the nominal pressure, which is preferably atmospheric pressure) the force applied by the liquid 5 in the duct 9 to the stopper member 16 will correspondingly increase. The stiffness of the spring member 15 is such that the spring member 15 will compress, further from its initial partially compressed state, by increasing force applied by the liquid 5 in the duct 9 to the stopper member 16, as pressure within the chamber 2 increases. The stiffness of the spring member 15 is such that the spring member 15 will compress, further from its initial partially compressed state, by an amount sufficient to allow the stopper member 16 to reach the first mechanical latch 20a (or beyond the first mechanical latch 20a) along the duct 9, when a predefinedmaximum threshold pressure is reached inside the chamber 2. Preferably, the maximum threshold pressure is between 2.1 -2.6 bar; most preferably the maximum threshold pressure is 2.4 bar or 2.5 bar. The stiffness of the spring member 15 may be between 1-10 N / mm; preferably the stiffness of the spring member 15 is between 3-7N / mm; more preferably the stiffness of the spring member 15 is between 4-6N / mm; most preferably the stiffness of the spring member 15 is between 5-6N / mm, for example, in a preferred embodiment the stiffness of the spring member 15 is 5.22N / mm. However, it should be understood that the stiffness of the spring member 15 may be any suitable value.

[0038] The sensor assembly 6 further comprises a second contact member 20b which is located along the duct 9, and which is configured to send a second signal to the controller when the stopper member 16 reaches a second predefined trigger position along the duct 9. The second contact member 20b may take any suitable form; for example the second contact member 20b may be in the form of a second mechanical latch, or the second contact member 20b may be in the form of a second electrical contact, or the second contact member 20b may be in any other suitable form. In the present example the second contact member 20b is in the form of a second mechanical latch 20b.

[0039] The stiffness of the spring member 15 is such that the spring member 15 will expand from its initial partially compressed state, as pressure within the chamber 2 decreases from the nominal pressure. The stiffness of the spring member 15 is such that the spring member 15 will expand from its initial partially compressed state, by an amount sufficient to allow the stoper member 16 to reach the second mechanical latch 20b (or beyond the second mechanical latch 20b) along the duct 9, when a predefined minimum threshold pressure is reached inside the chamber 2. Preferably the predefined minimum threshold pressure is between 0.9-1.9 bar; most preferably the predefined minimum threshold pressure is 1 bar (or less). The stiffness of the spring member 15 may be between 1-10 N / mm; preferably the stiffness of the spring member 15 is between 3-7N / mm; more preferably the stiffness of the spring member 15 is between 4-6N / mm; mostpreferably the stiffness of the spring member 15 is between 5-6N / mm, for example, in a preferred embodiment the stiffness of the spring member 15 is 5.22N / mm. However, it should be understood that the stiffness of the spring member 15 may be any suitable value.

[0040] In the present embodiment the second predefined trigger position corresponds to the position of the second mechanical latch 20b along the duct 9. When the stopper member 16 reaches the second mechanical latch 20b the stopper member 16 engages (preferably mechanically engages) the second mechanical latch 20b to trigger / initiate the second mechanical latch 20b to send the second signal to the controller.

[0041] The second signal will indicate that the liquid 5 is leaking from the chamber 2. Preferably, the controller is configured to shut down the battery module 1 in response to receiving a second signal from the second mechanical latch 20b, and / or to display an alert indicating that there is a leakage in the battery module 1.

[0042] As mentioned, the spring member 15 is compressed into an initial partially compressed state by a force applied by the liquid 5 in the duct 9 to the stopper member 16, when there is a nominal pressure, which is preferably atmospheric pressure, inside the chamber 2. The force applied by the liquid 5 in the duct 9 to the stopper member 16 results from the nominal pressure inside the chamber 2 and / or pressure applied by the volume of liquid 5 in the chamber 2 to the volume of liquid 5 in the duct 9.

[0043] Most preferably, when the battery module 1 in a state wherein none of the battery cells 3 are over-heating, or on fire, and none of the liquid 5 is leaking from the chamber 2, as is the state of the battery module 1 shown in Figure 1, the spring member 15 is in its initial partially compressed state; in this initial partially compressed state the spring member 15 is compressed by an amount to position the stopper member 16 in the duct 9 at a position which is somewhere between (preferably substantially midway between) the first predefine position and secondpredefined trigger position. In other words, in the present embodiment when the spring member 15 is in its initial partially compressed state, the spring member 15 is compressed by an amount to position the stopper member 16 in the duct 9 at a position which is somewhere between (preferably substantially midway between) the first mechanical latch 20a and second mechanical latch 20b. More specifically, in this embodiment when the spring member 15 is in its initial partially compressed state the spring member 15 is compressed by an amount to position the stopper member 16 in the duct 9 at a position which is between the first mechanical latch 20a and the second mechanical latch 20b; more specifically, the stopper member 16 is in a position in the duct 9 wherein the first mechanical latch 20a is located above the stopper member 16 and the second mechanical latch 20b is located below the stopper member 16. The stiffness of the spring member 15 is such that when the spring member 15 is in its initial partially compressed state the stopper member is located in the aforementioned position between the first mechanical latch 20a and the second mechanical latch 20b. The stiffness of the spring member 15 may be between 1-10 N / mm; preferably the stiffness of the spring member 15 is between 3-7N / mm; more preferably the stiffness of the spring member 15 is between 4-6N / mm; most preferably the stiffness of the spring member 15 is between 5-6N / mm, for example, in a preferred embodiment the stiffness of the spring member 15 5.22N / mm. However, it should be understood that the stiffness of the spring member 15 may be any suitable value.

[0044] If / when liquid 5 leaks from the chamber 2 the pressure applied by the liquid 5 in the duct 9 to the stopper member 16 will reduce; the more liquid 5 that leaks from the chamber 2 the more the pressure applied to the stopper member 16 will reduce. Since the spring member 15 is in an initial partially compressed state, the reduction in pressure will allow the partially compressed spring member 15 to expand from its partially compressed state; if enough liquid 5 leaks from the chamber 2, the pressure applied to the stopper member 16 will reduce such an amount sufficient to allow the partially compressed spring member 15 to expand to the point that the stopper member 16 reaches the second mechanical latch 20b along the duct9, at which point the stopper member 16 engages (preferably mechanically engages) the second mechanical latch 20b to trigger / initiate the second mechanical latch 20b to send the second signal to the controller. Hence the second signal will indicate if liquid 5 is leaking from the chamber 2.

[0045] The battery module 1 further comprises an exhaust channel 24 which is connected to the duct 9. The stopper member 16 is located between the exhaust channel 24 and the chamber 2 so that the stopper member 16 blocks the flow of liquid 5 from the chamber 2 and into the exhaust channel 24 until the spring member 15 has been compressed an amount sufficient to move the stopper member 16 to a position in which the stopper member 16 is no longer between the exhaust channel 24 and the chamber 2 and liquid 5 (and gas, smoke, fumes or the likes) can flow from the chamber 2 into the exhaust channel 24.

[0046] A junction 25 between the duct 9 and the exhaust channel 24 is located on the first side of the stopper member 26. The junction 25 between the duct 9 and the exhaust channel 24 is located further away from the stopper member 16 than the first predefined trigger position (the first mechanical latch 20a), so that the stopper member 16 will reach the first predefined trigger position (the first mechanical latch 20a) before reaching the second position in which fluid 5 can flow from the chamber 2 into the exhaust channel 24. In other words, in the present embodiment the junction 25 between the duct 9 and the exhaust channel 24 is located further away from the stopper member 16 than the first mechanical latch 20a, so that the stopper member 16 will reach the first mechanical latch 20a to trigger / initiate the first mechanical latch 20a to send the first signal to the controller, before reaching the second position in which fluid 5 can flow from the chamber 2 into the exhaust channel 24.

[0047] In another embodiment the location of junction 25 between the duct 9 and the exhaust channel 25 corresponds to, or substantially corresponds to, to the location of the first predefined trigger position (first mechanical latch 20a), for example, the first predefined trigger positionmay be located immediately at the start of the junction 25; for example the first mechanical latch 20a could be located at, or substantially at, the junction 25, so that the stopper member 16 will simultaneously reach the first predefined trigger position (first mechanical latch 20a) and the second position in which fluid can flow from the chamber into the exhaust channel.

[0048] Figures 2a and 2b show the battery module 1 when in use. Referring first to the example situation depicted in Figure 2a which shows a situation wherein the liquid 5 is leaking from the chamber 2.

[0049] As the liquid 5 leaks from the chamber 2 the pressure applied by the liquid 5 in the duct 9 to the stopper member 16 will reduce; the more liquid 5 that leaks from the chamber 2 the more the pressure applied to the stopper member 16 will reduce. Since the spring member 15 is initially in a partially compressed state, the reduction in pressure will allow the partially compressed spring member 15 to expand from its initial partially compressed state. Figure 2a shows a situation wherein enough liquid 5 has leaked from the chamber 2, to cause the pressure applied to the stopper member 16 to reduce an amount sufficient to allow the spring member 15 to expand to the point that the stopper member 16 reaches the second predefined trigger position (the second mechanical latch 20b) along the duct 9. When the stopper member 16 reaches the second mechanical latch 20b the stopper member engages (preferably mechanically engages) second mechanical latch 20b to trigger / initiate the second mechanical latch 20b to send the second signal to the controller.

[0050] The second signal will indicate that the liquid 5 is leaking from the chamber 2. Preferably, the controller is configured to shut down the battery module 1 in response to receiving a second signal from the second mechanical latch 20b and / or to display an alert indicating that there is a leakage in the battery module 1.

[0051] Referring to the example situation depicted in Figure 2b which shows a situation wherein on of the battery cells 3 in the chamber 2 have caught fire. The fire will cause the temperature within the chamber 2 to rise; the rising temperature within the chamber 2 will heat at least some of the liquid 5 to above the phase change temperature of the liquid 5, causing at least some of the liquid 5 to change phase from a liquid 5 to a gas. The increase in the amount of gas in the chamber 2 increases the pressure within the chamber 2. The increasing pressure within the chamber 2 causes an increase in the force that the liquid 5 in the duct 9 applies to the stopper member 16. The increasing force that the liquid 5 in the duct 9 applies to the stopper member 16 causes the spring member 15 to compress further from its initial partially compressed state. Figure 2b shows a situation wherein enough liquid 5 has undergone phase change to a gas, to cause the pressure within the chamber 2 to increase an amount sufficient to cause the liquid 5 in the duct 9 to apply a force to the stopper member 16 to compress the spring member 15 to the point that the stopper member 16 reaches the first mechanical latch 20a along the duct 9. When the stopper member 16 reaches the first mechanical latch 20a the stopper member engages (preferably mechanically engages) first mechanical latch 20a to trigger / initiate the first mechanical latch 20a to send the first signal to the controller.

[0052] The first signal will indicate that one of the battery cells 3 has caught fire. Preferably, the controller is configured to shut down the battery module 1 in response to receiving a first signal from the first mechanical latch 20b.

[0053] Furthermore, in this embodiment the temperature sensor 17 which is attached to the battery cell 3 which caught fire will sense that the temperature of that battery cell 3 has exceeded the predefined threshold temperature. Accordingly, that temperature sensor 17 will send an alert signal to the controller. Preferably, in response to receiving an alert signal the controller will shut down the battery module 1. Thus, in the present embodiment there are two means for detecting if / when a battery cell 3catches fire or is overheating, and two corresponding routes for shutting down the battery module 1 in response to detecting a fire or overheating.

[0054] The stopper member 16 is located between the exhaust channel 24 and the chamber 2 to block the flow of fluid 5 from the chamber 2 and into the exhaust channel 24 until the spring member 15 has been compressed, by the force applied by the liquid 5 in the duct 9 to the stopper member 16, an amount sufficient to move the stopper member 16 to a second position in which the stopper member 16 is no longer between the exhaust channel 24 and the chamber 2 and fluid 5 can flow from the chamber 2 into the exhaust channel 24. Figure 2b shows the stopper member 16 has been moved to the second position in which the stopper member 16 is no longer between the exhaust channel 24 and the chamber 2; specifically Figure 2b shows that the spring member 15 has been compressed such an amount that the stopper member 16 has been moved beyond the junction 25. When the stopper member 16 is in said second position liquid 5 and / or heat, and / or flames, and / or fumes from the fire, can be feely exhausted from the chamber 2 and into the exhaust channel 24.

[0055] Referring back to Figure 1 it can be seen that in this exemplary embodiment the battery module 1 further comprises a filler material 12. However, it should be understood that the filler material 12 is an optional feature of the present invention. The filler material 12 may take any suitable form. In a preferred embodiment the filler material 12 comprises synthetic porous material. Most preferably the synthetic porous material may comprise aerogel (preferably silica-based aerogel or carbon-based aerogel). In the present embodiment the filler material 12 is arranged to surround the plurality of battery cells 3. The filler material 12 is arranged inside the chamber 2 and it located above the surface of the liquid 5 in the chamber 2. Preferably the filler material 12 is arranged to fill substantially all of the vacant volume which is within the chamber 2; in other words filler material 12 is preferably arranged to fill substantially all of the volume of the chamber 2 which is not already occupied by a physical component (such as a battery cell 3, or sleeve 8, or liquid 5, or any other physical component of the battery module 1).

[0056] In an embodiment the filler material 12 may further comprise phase-change material. For example, in an embodiment the filler material 12 comprises porous material (such as synthetic porous material), and phase change material is provided in the pores of the porous material. In another embodiment the filler material 12 may further comprise intumescent material. For example, in an embodiment the filler material 12 comprises porous material (such as synthetic porous material), and intumescent material is provided in the pores of the porous material. In another embodiment the filler material 12 may comprise a laminar structure. For example, in an embodiment the filler material 12 comprises a layer of porous material (such as synthetic porous material), and / or a layer of phase change material, and / or a layer of intumescent material.

[0057] In an embodiment the battery module 1 may further comprise a thermally conductive material which is positioned between the plurality of battery cells 3 / sleeves 8 and the filler material 12, which facilitates the transfer of thermal energy from the plurality of battery cells 3 / sleeve 8 to the filler material 12.

[0058] In further embodiment the battery module 1 may further comprise a shield member which is positioned inside the chamber 2 and arranged to be perpendicular to longitudinal axes of the battery cells 3. Most preferably the shield member will overlay the positive electric poles 3a of all the battery cell 3 in the chamber 2. When a battery cell 3 explodes the explosion will typically be in the direction in which the positive electric pole 3a is facing. Also, in the event of an explosion of a battery cell 3 the debris from the explosion is typically projected in the direction in which the positive electric pole 3a is facing. The shield member will block any projectiles from impacting the chamber 2 which is above the positive electric pole 3a of each battery cell 3; and any blocked projectiles will rebound off the shield member and fall into the liquid. In an embodiment the shield member comprises thermally conductive material. In an embodiment the shield member is preferably arranged to be in thermal contact with the filler material 12, so heat absorbed by the shield member can be transferred to the filler material 12.

[0059] Referring again to Figure 1 it can be seen that in this exemplary embodiment the battery module 1 further comprises carbon nanotubes 50 which are arranged to conduct heat away from the plurality of battery cells 3. However, it should be understood that the carbon nanotubes 50 are an optional feature of the present invention.

[0060] The carbon nanotubes 50 may be provided in any suitable arrangement in the battery module 1. In the present embodiment the carbon nanotubes 50 are arranged to conduct heat away from the plurality of battery cells 3 and into the liquid 5. The carbon nanotubes 50 may be fully submerged (i.e. the full length of the carbon nanotubes 50 is submerged in the liquid 5) or partially submerged in the liquid 5 (i.e. a portion of the length of the carbon nanotubes 50 is submerged in the liquid 5 while another portion of the length of the carbon nanotubes is not submerged in the liquid 5). In another embodiment the only some of the carbon nanotubes 50 may be submerged or partially submerged while other of the carbon nanotubes are not submerged or partially submerged in the liquid. In another embodiment the carbon nanotubes 50 are not submerged in the liquid 5 and rather are positioned proximate to the liquid and heat transfer from the carbon nanotubes 50 to the liquid 5 is by convection.

[0061] The carbon nanotubes 50 may be of any suitable length. Preferably the carbon nanotubes each have a length between 1mm-1cm.

[0062] In the embodiment shown in Figure 1 the carbon nanotubes 50 are located inside the chamber; specifically, the carbon nanotubes 50 are attached to each of the plurality of sleeves 8 and are submerged in the liquid 5. Even more specifically each sleeve 8 comprises an open end 8a and a closed end 8b; a respective battery cell 3 can be inserted into a respective sleeve 8 via the open end 8a. Optionally, each battery cell 3 can be attached to the closed end 8b of a respective sleeve 8, inside the sleeve 8 (i.e. an inner surface of the sleeve at the closed end 8b); for example, the battery cell 3 can be electrically attached to the closed end 8b of the sleeve8, inside the sleeve 8, via an electrically conductive glue. Fixing the battery cell 3 to the closed end 8b of the sleeve 8 will help to reduce the possibility of the battery cell 3 being projected from the sleeve 8 in the event of the battery cell 3 exploding. In this embodiment each sleeve 8 is positioned so that the closed end 8b of the respective sleeve 8 is located below the surface 35 of the liquid 5 in the chamber 2. In this example the carbon nanotubes 50 are attached to an outside surface of each respective sleeve 8; more specifically the carbon nanotubes 50 are attached to an outside surface of each respective sleeve 8 at the closed end 8b. Since the closed end 8b of each respective sleeve 8 is located below the surface 35 of the liquid 5, the carbon nanotubes 50 which are attached to the outer surface of the closed end 8b are also located below the surface 35 of the liquid 5 in the chamber 2. In a variation of this embodiment carbon nanotubes 50 may be further provided along the length of each sleeve 8; in this case some of the carbon nanotubes 50 may be located below the surface 35 of the liquid 5 in the chamber 2, and some other of the carbon nanotubes 50 may be located above the surface 35 of the liquid 5 in the chamber 2 and / or some other of the carbon nanotubes 50 may be partially submerged in the liquid 5.

[0063] Heat from a battery cell 9 is conducted to the sleeve 8 and the carbon nanotubes 50 conduct the heat away from the sleeve 8 and into the liquid 5, in this way the carbon nanotubes 50 help to keep the battery cells 3 cool. In the event a battery cell 3 overheats or catches fire, the carbon nanotubes 50 will promote the conduction of heat away from the overheating or on fire battery cell 3 into the liquid 5, thereby increasing the speed at which the liquid 5 is heated and thereby increasing the speed of the phase change from the liquid 5 to a gas, which in turn increases the speed at which pressure within the chamber 2 rises, which in turn will increase the speed at which the first signal will be send to the controller. In other words, the carbon nanotubes 50 will allow for quicker detection of a battery cell 3 catching fire or overheating.

[0064] In the exemplary battery module 1 shown in Figure 1 a plurality of channels 52 are defined between the carbon nanotubes 50 attached tothe sleeve 8; these channels 52 allow liquid 5 to circulate between carbon nanotubes 50 and this promotes the transfer of heat energy from the carbon nanotubes 50 into the liquid 5.

[0065] In the exemplary battery module 1 shown in Figure 1 the carbon nanotubes 50 are in the form of a layer 51 of carbon nanotubes 50; a respective layer 51 of carbon nanotubes 50 is attached to the closed end 8b of each respective sleeve 8. Preferably, each respective layer 51 of carbon nanotubes 50 further comprises interface material (e.g. rubber, or glue, or PVC), wherein each respective layer 51 of carbon nanotubes 50 is secured within the battery module 1 via the interface material (e.g. each respective layer 51 of carbon nanotubes 50 is secured to the closed end 8b of a respective sleeve 8 via the interface material). As shown in Figure 1, in this example each respective layer 51 of carbon nanotubes 50 is on a plane and the carbon nanotubes 50 extend perpendicular to the plane. However, it should be understood that it is not essential that the carbon nanotubes 50 are in the form of a layer 51. Preferably, each layer 51 of carbon nanotubes 50 comprises at least a portion which is arranged on a plane which is perpendicular (or substantially perpendicular) to a longitudinal axis of each of each respective battery cell 3, so that each layer 51 conducts heat away from the plurality of battery cells 3 in a direction which is substantially parallel to the longitudinal axis of each of each respective battery cell 3.

[0066] In yet another embodiment carbon nanotubes 50 are attached directly to the battery cells 3. For example, in an embodiment wherein the battery module 1 is without sleeves 8, the carbon nanotubes 50 may be attached directly to the battery cells 3.

[0067] Referring to the exemplary battery module 1 shown in Figure 1 it can be seen that the battery module 1 further comprises carbon nanotubes 50 which are attached to an outer surface 2a of the chamber 2. Preferably, as is the case in the battery module 1 shown in Figure 1, the carbon nanotubes 50 are attached to an outer surface 2a of the chamber 2 at a bottom side 2b of the chamber 2. In this case the liquid 5 will contact aninside surface 2c of the bottom side 2b of the chamber 2, while the carbon nanotubes 50 are attached the outer surface 2a of the bottom side 2b of the chamber 2, thereby ensuring that the carbon nanotubes 50 are in close proximity to the liquid 5 inside the chamber 5 regardless of the level of liquid 5 inside the chamber 2. It should be understood that carbon nanotubes 50 may additionally, or alternatively, be attached to any other part (e.g. the outside surface of the side walls) of the chamber 2.

[0068] The carbon nanotubes 50 which are attached to an outer surface 2a of the chamber 2 will also serve to conduct heat away from the plurality of battery cells 3. Specifically, heat from a battery cell is conducted to the sleeve 8; and the carbon nanotubes 50 on the respective sleeves 8 will conduct the heat away from the respective sleeves 8 and into the liquid 5; at least some of the heat in the liquid 5 will be conducted to the chamber 2 (in particular, at least some of the heat in the liquid 5 will be conducted to the parts of the chamber 2 which are submerged in liquid 5); and the carbon nanotubes 50 which are attached to an outer surface 2a of the chamber 2 will conduct heat away from the chamber 2 and into the surrounding atmosphere. In this way the carbon nanotubes 50 help to keep the battery cells 3 cool.

[0069] The carbon nanotubes 50 which are attached to an outer surface 2a of the chamber 2 may be of any suitable length. Preferably the carbon nanotubes each have a length between 1 mm-1cm.

[0070] In the exemplary battery module 1 shown in Figure 1 a plurality of channels 52 are defined between the carbon nanotubes 50 which are attached to an outer surface 2a of the chamber 2; these channels 52 allow air to circulate between carbon nanotubes 50 and this promotes the transfer of heat energy from the carbon nanotubes 50 into the surrounding atmosphere.

[0071] In the exemplary battery module 1 shown in Figure 1 the carbon nanotubes 50 which are attached to an outer surface 2a of the chamber 2are in the form of a layer 151 of carbon nanotubes 50; a layer 151 of carbon nanotubes 50 is attached the outer surface 2a of the chamber 2 at a bottom side 2b of the chamber 2. Preferably, the layer 151 of carbon nanotubes 50 further comprises interface material (e.g. rubber, or glue, or PVC), which secures the layer 151 of carbon nanotubes 50 to the outer surface 2a of the chamber 2. However, it should be understood that it is not essential that the carbon nanotubes 50 which are attached to an outer surface 2a of the chamber 2 are in the form of a layer 151. In this example the layer 151 of carbon nanotubes 50 is arranged on a plane which is perpendicular to a longitudinal axis of each of each respective battery cell 3, so that the layer 151 conducts heats away from the chamber 2 in a direction which is substantially parallel to the longitudinal axis of each of each respective battery cell 3. As shown in Figure 1, in this example the layer 151 of carbon nanotubes 50 is on a plane and the carbon nanotubes 50 extend perpendicular to the plane.

[0072] Figure 3 illustrates a battery module 30 according to a further embodiment of the present invention. The battery module 30 has many of the same features as the battery module 1 shown in Figure 1 and like features are awarded the same reference numbers.

[0073] Unlike the battery module 1, in the battery module 30 shown in Figure 3, the plurality of battery cells 3 are arranged within the chamber 2 so that the positive electric pole 3a of each respective battery cell 3 is facing in a direction which is towards the liquid 5. In a preferred embodiment, and as is the case for the exemplary battery module 30 embodiment shown in Figure 3, the battery cells 3 are arranged within the chamber 2 so the positive electric pole 3a of each respective battery cell 3 is below a surface 35 of the liquid 5 in the chamber 2.

[0074] When a battery cell 3 explodes the explosion 130 will typically be in the direction in which the positive electric pole 3a is facing. Also, in the event of an explosion 130 of a battery cell 3 the debris from the explosion 130 is typically projected from the positive electric pole 3a of the batterycell 3. Advantageously, by having the battery cells 3 arranged so that the positive electric pole 3a of each respective battery cell 3 is facing in a direction which is towards the liquid, or, having the battery cells 3 arranged so that the positive electric pole 3a of each respective battery cell 3 below the surface 35 of the liquid 5 in the chamber 2, the explosion 130 can be somewhat contain by the liquid 5 and debris from the explosion 130 will be projected into the liquid 5, which reduces the impact of the explosion 130, and in particular reduces the impact of the explosion 130 on neighbouring battery cells 3.

[0075] Figure 4 illustrates a battery module 40 according to a further embodiment of the present invention. The battery module 40 has many of the same features as the battery module 1 shown in Figure 1 and like features are awarded the same reference numbers.

[0076] In the battery module 40 the duct 9 and sensor assembly 6 are located in a different position to the position at which they are located in the battery module 1 shown in Figure 1. Specifically, in the battery module1 shown in Figure 1 the duct 9 is fluidly connected to the chamber 2 at a position which is below the surface 35 of the liquid 5, so that at least some of the liquid 5 is present in the duct 9; and the liquid 5 present in the duct 9 applies a force to the stopper member 16 of the sensor assembly 6. However, in the in the battery module 40 shown in Figure 4 the liquid 5 does not apply a force to the stopper member 16. Rather, in the battery module 40 shown in Figure 4 the duct 9 is fluidly connected to the chamber2 at a position which is above the surface 35 of the liquid 5; air and / or gas (e.g. the gas form of the liquid 5) in the chamber 2 applies a force to the stopper member 16 which partially compresses the spring member 15. Importantly, in this embodiment the filler material 12 does not completely fill the entire vacant volume inside the chamber 2; rather there is a vacant space 49 inside the chamber 2 which is without filler material 12; this vacant space 49 is filed with air and / or gas (e.g. the gas form of the liquid 5). Preferably the vacant space 49 is fluidly connected between the liquid 5 and the stopper member 16, so that when the temperature inside the chamber 2 increases to a temperature at which the liquid 5 changes phaseto a gas, the gas will flow into the vacant space 49 to increase the pressure in the vacant space 40, and thereby increase the force applied by the air and / or gas in the vacant space 49 to the stopper member 16.

[0077] The force applied by the air and / or gas (e.g. the gas form of the liquid 5) in the vacant space 39 in the chamber 2 to the stopper member 16 ensures that the spring member 15 is initially in a partially compressed state. The force applied by the air and / or gas in the chamber 2 to the stopper member 16, may result from nominal pressure, which is preferably atmospheric pressure, inside the chamber 2. In other words, the spring member is compressed into its initial partially compressed state by nominal pressure, which is preferably atmospheric pressure, inside the chamber 2. The stiffness of the spring member 15 is such that the spring member 15 will compress to its initial partially compressed state by force applied by the air and / or gas in the chamber 2 to the stopper member 16, wherein there is a nominal pressure, which is preferably atmospheric pressure, inside the chamber 2. It can be that some of the liquid 5 inside the chamber 2 may have changed phase to a gas, the gas will flow into the vacant space 49, which contributes to the force applied to the stopper member 16, to compress the spring member 15 into its initial partially compressed state; in other words the force applied to the stopper member 16 which compresses the spring member 15 into its initial partially compressed state may not necessarily result exclusively from atmospheric pressure, which is preferably atmospheric pressure, inside the chamber 2. Preferably, the nominal pressure inside the vacant space 49 of the chamber 2 is between 1.1 -2.3 bar; most preferably the nominal pressure is 2 bar. The stiffness of the spring member 15 may be between 1-10 N / mm; preferably the stiffness of the spring member 15 is between 3-7N / mm; more preferably the stiffness of the spring member 15 is between 4-6N / mm; most preferably the stiffness of the spring member 15 is between 5-6N / mm, for example, in a preferred embodiment the stiffness of the spring member 15 is 5.22N / mm. However, it should be understood that the stiffness of the spring member 15 may be any suitable value.

[0078] When the temperature inside the chamber increases, for example, if / when one of the battery cells catch fire, the heat will cause at least a portion of the liquid 5 to change phase to a gas. The gas will flow into the vacant space 49, and thereby increase the pressure inside the chamber 2, more specifically will increase the pressure within the vacant space 49 of the chamber 2. As pressure within the chamber 2 increases, specifically as pressure within the vacant space 49 of the chamber 2 increases, the force applied by air and / or gas in the chamber 2 to the stopper member 16 will correspondingly increase. The stiffness of the spring member 15 is such that the spring member 15 will compress, further from its initially partially compressed state, by increasing force applied by air and / or gas in the vacant space 49 of the chamber 2 to the stopper member 16, as pressure within the chamber 2 increases. The stiffness of the spring member 15 is such that the spring member 15 will compress further from its initially partially compressed state, by an amount sufficient to allow the spring member 15 to reach the first predefined trigger position (or beyond the first predefined trigger position) along the duct 9, when a predefined maximum threshold pressure is reached inside the chamber 2. In other words the stiffness of the spring member 15 is such that the spring member 15 will compress further from its initially partially compressed state by force applied by air and / or gas in the vacant space 49 of the chamber 2 to the stopper member 16, by an amount sufficient to allow the spring member 15 to reaches the first mechanical latch 20a along the duct 9, when a predefined maximum threshold pressure is reached inside the vacant space 49 of the chamber 2. Preferably, the predefined maximum threshold pressure inside the vacant space 49 of the chamber 2, is between 2.1 -2.6 bar; most preferably the predefined maximum threshold pressure is 2.4 bar or 2.5 bar. The stiffness of the spring member 15 may be between 1-10 N / mm; preferably the stiffness of the spring member 15 is between 3- 7N / mm; more preferably the stiffness of the spring member 15 is between4-6N / mm; most preferably the stiffness of the spring member 15 is between5-6N / mm, for example, in a preferred embodiment the stiffness of the spring member 15 is 5.22N / mm. However, it should be understood that the stiffness of the spring member 15 may be any suitable value.

[0079] When the stopper member 16, reaches the first mechanical latch 20a the stopper member engages (preferably mechanically engages) first mechanical latch 20a to trigger / initiate the first mechanical latch 20a to send the first signal to the controller.

[0080] Similarly, if liquid 5 is leaking from the chamber 2 then the pressure within the chamber will decrease and the force applied by air and / or gas in the vacant space 49 of the chamber 2 to the stopper member 16, will decrease. As liquid 5 continues to leak the force applied by air and / or gas in the chamber 2 to the stopper member 16, will decrease by an amount sufficient to allow the spring member 15 to expand from its initial partially compressed state so that the stopper member 16 reaches the second predefined trigger position (or beyond the second predefined trigger position) along the duct 9, when a predefined minimum threshold pressure is reached inside the vacant space 49 of the chamber 2. In other words, as liquid 5 continues to leak the force applied by air and / or gas in the vacant space 49 of the chamber 2 to the stopper member 16, will decrease by an amount sufficient to allow the spring member 15 to expand from its initial partially compressed state so that the stopper member 16 reaches the second mechanical latch 20b along the duct 9. When the stopper member 16, reaches the second mechanical latch 20b the stopper member engages (preferably mechanically engages) second mechanical latch to trigger / initiate the second mechanical latch to send the second signal to the controller. Preferably, the predefined minimum threshold pressure inside the vacant space 49 of the chamber 2 is between 0.9-1.9 bar; most preferably the predefined minimum threshold pressure is 1 bar (or less).

[0081] Figures 5a and 5b illustrate a battery module 60 according to a further embodiment of the present invention. The battery module 60 has many of the same features as the battery module 1 shown in Figure 1 and like features are awarded the same reference numbers.

[0082] As mentioned in the present disclosure it should be understood that the battery cells 3 may take any suitable form. In the exemplary battery module 60 shown in Figure 5 the battery cells 3 each comprise pouch cells 63. Some type of battery cells, such as pouch cells 63 for example, are known to reversibly inflate and deflate during respective charging and discharging of the pouch cell 63 - this temporary inflation and deflation is due to gas generation from electrochemical reactions that occur within the pouch cell 63 during respective charging and discharging of the pouch cell 63. However, pouch cells 63 also slowly irreversibly inflate over time due to aging (more specifically, due to irreversible chemical processes that occur over time within the pouch cell 63, that generate gas over the life cycle of the pouch cell 63 which permanently increase the volume of the pouch cell 63 over time). When a pouch cell 63 irreversibly inflates to a volume which is above a predefined threshold volume, then that pouch cell 63 will fail to meet necessary performance and safety requirements, and thus needs to be replaced.

[0083] Typically, the reversible inflation and deflation during respective charging and discharging of a pouch cell 63 can cause the volume of the pouch cell to vary between 0% and 10% of the nominal volume of the pouch cell 63; on the other hand, the irreversible inflation of the pouch cell 63 over time, due to aging, may result in the volume of the pouch cell increasing by up to 20%. Accordingly, if the volume of a pouch cell 63 has increased by 11 % or more above it's nominal volume, then the volume increase is likely to be as a result of irreversible inflation of the pouch cell 63, due to aging.

[0084] In the assembly 60, the sensor assembly 6 further comprises a third contact member 61c which is located along the duct 9, and which is configured to send a third signal to the controller when the stopper member 16 reaches a third predefined trigger position along the duct 9. The third contact member 61c may take any suitable form; for example, the third contact member 61c may be in the form of a third mechanical latch, or the third contact member 61c may be in the form of a third electrical contact, or the third contact member 61c may be in any other suitableform. In the present embodiment the third contact member 61c is in the form of a third mechanical latch 61c.

[0085] The spring member 15 is partially compressed by force applied by the liquid 5 in the duct 9 to the stopper member 16. This ensures that the spring member 15 is initially in a partially compressed state. The force applied by the liquid 5 in the duct 9 to the stopper member 16 results from nominal pressure within the chamber 2 and / or pressure applied by the liquid 5 in the chamber 2 to the volume of liquid in the duct 9. The stiffness of the spring member 15 is such that the spring member 15 will partially compress, by force applied by the liquid 5 in the duct 9 to the stopper member 16, when there is a nominal pressure (which is preferably atmospheric pressure) inside the chamber 2. Thus, the spring member 15 will be in an initial partially compressed state. Preferably, the nominal pressure inside the chamber 2 is between 1.1 -2.3 bar; most preferably the nominal pressure inside the chamber 2 is 2 bar.

[0086] During operation, when volume of any one or more of pouch cells 63 within the chamber 2 change, this in turn will change the pressure inside of the chamber 2. More specifically, when one or more of the pouch cells 63 are charging the volume of these one or more of the pouch cells 63 will temporally increase, typically, anywhere between 0%-10%; this will result in an increase in pressure inside the chamber 2 from the nominal pressure, and the force applied by the liquid 5 in the duct 9 to the stopper member 16 will correspondingly increase. However, the third mechanical latch 61c is located along the duct 9, at a position which ensures that the stopper member 16 only reaches the third mechanical latch 61c when the pressure within the chamber 2 reaches a predefined threshold pressure.

[0087] In this example, as shown in Figure 5a, when the one or more of the pouch cells 63 undergo a volume expansion which is below 11 %, then the pressure within the chamber 2 will not increase to the predefined threshold pressure; thus the stopper member 16 will not reach the third mechanical latch 61c when the pouch cells 63 reversibly expand whencharging, thereby allowing for reversible inflation and deflation during respective charging and discharging of a pouch cell 63. So, Figure 5a illustrates a battery module 60 when the pressure inside the chamber 2 is below the predefined threshold pressure.

[0088] However, overtime, the one or more pouch cell 63 will suffer irreversible inflation, due to aging, which will result in the volume of one or more pouch cells 63 increasing by up to 20%. This will result in the pressure inside the chamber 2 increasing from the nominal pressure and the force applied by the liquid 5 in the duct 9 to the stopper member 16 will correspondingly increase.

[0089] As pressure within the chamber 2 increases from the nominal pressure, the force applied by the liquid 5 in the duct 9 to the stopper member 16 will correspondingly increase. The stiffness of the spring member 15 is such that the spring member 15 will compress, further from its initial partially compressed state, by increasing force applied by the liquid 5 in the duct 9 to the stopper member 16, as pressure within the chamber 2 increases. The stiffness of the spring member 15 is such that the spring member 15 will compress, further from its initial partially compressed state, by an amount sufficient to allow the stopper member 16 to reach the third mechanical latch 61c, when the pressure inside the chamber 2 reaches said predefined threshold pressure, as shown in Figure 5b. So, Figure 5b illustrates a battery module 60 when the pressure inside the chamber 2 is equal to, or above, the predefined threshold pressure.

[0090] In this example the predefined threshold pressure is equal to the pressure inside the chamber 2 when the volume of one or more pouch cells 63 increases by a predefined threshold volume expansion, which in this example is 15% (the predefined threshold pressure may be determined in a calibration step wherein the volume or one or more of the pouch cells 63 is increased by 15% and the pressure within the chamber 2 is measured). The third mechanical latch 61c is located along the duct 9, at a position which ensures that the stopper member 16 reaches the third mechanical latch 61cwhen the pressure within the chamber 2 reaches said predefined threshold pressure.

[0091] Thus, when the volume of one or more pouch cells 63 increases by 15%, due to aging, this will cause the pressure within the chamber 2 to increase to the predefined threshold pressure (or above the predefined threshold pressure), which in turn will increase the force applied by the liquid 5 in the duct 9 to the stopper member 16. The force applied by the liquid 5 in the duct 9 to the stopper member 16 will move the stopper member 16 to the third mechanical latch 61c; the stopper member 16 will trigger / initiate the third mechanical latch 61c to send the third signal to the controller.

[0092] The third signal will indicate that the volume of one or more of the pouch cells 63 in the battery module 60, has irreversibly inflated, due to aging, by an amount which is larger than a predefined threshold volume expansion (which in this example 15% volume expansion). It should be understood that the predefined threshold volume expansion could be any suitable value; most preferably the predefined threshold volume expansion will be greater than 10% because many pouch cells 63 can undergo reversable volume expansion of up to 10% during charging - and ideally the third mechanical latch 61c should not be triggered to send the third signal to the controller when a pouch cell 63 undergoes reversable volume expansion. Preferably, the third mechanical latch 61c should only be triggered to send the third signal to the controller when a pouch cell 63 undergoes irreversible volume expansion which is large enough to affect the functionality and / or safety of that pouch cell 63. A volume increase of 11 % of more is more likely to be an irreversible volume increase of the pouch cells 63 due to aging, thus the predefined threshold volume expansion may be 11 % or more, or preferably 12% or more, or most preferably 15% or more.

[0093] Preferably, in response to receiving the third signal from the third mechanical latch 61c, the controller is configured to display an alertindicating that one or more pouch cells 63 requires replacement due to old- age. In response to the alert displayed by the controller a user may replace the pouch cells 63 that have irreversibly inflated to a volume which is above a predefined threshold volume.

[0094] Although Figures 5a and 5b illustrate the battery module 60 without sleeves 8, it should be understood that in a variation of the exemplary battery module 60 shown in Figures 5a an 5b the battery module 60 may further comprise respective sleeves 8, and each pouch cell 63 may be held within a respective sleeve 8 in a similar fashion to the way in which the battery cells 3 in assembly 1 are held within respective sleeves 8. Each sleeve 8 will preferably comprise an open end 8a and a closed end 8b; a respective pouch cell 63 can be inserted into a respective sleeve 8 via the open end 8a. Each respective pouch cell 63 may be attached to the inside of the sleeve 8 at the closed end 8b using attachment means, such a glue, preferably electrically conductive glue. Optionally, carbon nanotubes 50 may be attached to each respective sleeve 8 in which a pouch cell 63 is held; for example, carbon nanotubes 50 may be provided in the form of a layer 51 of carbon nanotubes 50 attached to a closed end 8b (an outer surface of closed end) of each respective sleeve 8. In a further embodiment, such as an embodiment of the battery module 60 without sleeves, optionally, carbon nanotubes 50 may be attached to each pouch cell 63.

[0095] Furthermore, optionally, in the battery module 60, insulating material may be interposed between each of the pouch cells 63; for example, adjacent pouch cells 63 may be separated from each other by a layer of insulating material.

[0096] According to a further aspect of the present invention there is provided an electric or hybrid vehicle comprising a battery module according to anyone of the above-mentioned battery module embodiments. In particular, there is provided an electric or hybrid aircraft, comprising a battery module according to anyone of the above-mentioned battery module embodiments.

[0097] It should be noted that the carbon nanotubes 50 may be provided on any type of battery module; in other words, although the present disclosure describes providing carbon nanotubes 50 on exemplary battery modules 1, 30, 40, 60 shown in Figures 1-5a,5b, all of which have a chamber 2, liquid 5 and sensor assembly 6, the carbon nanotubes 50 may be provided in another other type of battery module. For example, the carbon nanotubes 50 may be provided in a battery module which is known in the art which does not have a liquid 5, (such as the battery module described in WO2023079345), wherein the carbon nanotubes 50 are arranged to conduct heat away from the battery cells of the battery module. The use of carbon nanotubes 50 in a battery module, in particular the use of carbon nanotubes 50 in a battery module for an electric or hybrid vehicle (such as an electric or hybrid aircraft), to conduct heat away from the battery cells of the battery module, is unique.

[0098] According to a further aspect of the present invention there is provided a battery module, comprising, a housing; a plurality of battery cells, preferably arranged in parallel within said housing; and carbon nanotubes which are arranged to conduct heat away from the plurality of battery cells. Preferably, each battery cell has a first electric pole at a first end and a second electric pole at a second end. Preferably the carbon nanotubes each have a length between 1mm-1cm.

[0099] In a preferred embodiment the carbon nanotubes are in the form of a layer of carbon nanotubes. Most preferably the layer of carbon nanotubes is on a plane and the carbon nanotubes extend perpendicular to the plane. In an embodiment the layer of carbon nanotubes are arranged on a plane which is perpendicular to a longitudinal axis of each respective battery cell, so that the carbon nanotubes conduct heat away from the plurality of battery cells in a direction which is parallel to the longitudinal axis of each of each respective battery cell. In an embodiment the layer of carbon nanotubes further comprises interface material, wherein the layer of carbon nanotubes is secured within the battery module via the interface material. The interface material may comprise any of, rubber, or glue, or PVC, for example. In an embodiment the layer of carbon nanotubes hasone or more channels, defined between carbon nanotubes, through which air can circulate; most preferably, the layer of carbon nanotubes have one or more channels, defined between clusters of carbon nanotubes, through which air can circulate.

[0100] In an embodiment said carbon nanotubes are attached to the housing of the battery module. Preferably the said carbon nanotubes are attached to an outside of the housing. Heat generated by the plurality of battery cells is conducted to the housing and said heat is conducted away from the housing via the carbon nanotubes. In an embodiment said carbon nanotubes attached to the battery cells. Heat generated by the plurality of battery cells is conducted away from the battery cells directly via the carbon nanotubes. In an embodiment some carbon nanotubes are attached to the housing of the battery module and some carbon nanotubes are also attached directly to the battery cells.

[0101] In an embodiment the battery module comprises a plurality of sleeves, and a respective battery cell is held within a respective sleeve; and carbon nanotubes (e.g. a respective layer of carbon nanotubes) are attached to the sleeves. Heat generated by each respective battery cells is conducted to the respective sleeve within which that respective battery cell is held; and the heat is conducted away from each respective battery cell via the carbon nanotubes which are attached to that sleeve. In an embodiment some carbon nanotubes are attached to the housing of the battery module and some carbon nanotubes are attached to the sleeves.

[0102] According to an aspect of the present invention there is provided a method of cooling one or more battery cells in a battery module which comprises a housing and a plurality of battery cells arranged within said housing, the method comprising the step of using carbon nanotubes to conduct heat away from one or more of the battery cells. Said battery module may be any of the battery module embodiments described in the present disclosure.

[0103] Various modifications and variations to the described embodiments of the invention will be apparent to those skilled in the art without departing from the scope of the invention as defined in the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiment.

Claims

Claims1. A battery module (1), comprising, a chamber (2); a plurality of battery cells (3) arranged within said chamber (2); a liquid (5) which is located within the chamber (2), and which can change phase to a gas when heated above a predefined temperature; a sensor assembly (6) which is configured to detect changes in pressure within the chamber (2) caused by the change in phase of the liquid (5) to a gas.

2. The battery module according to claim 1 wherein the chamber is airtight, or, wherein the chamber is selectively configurable to be air-tight.

3. The battery module according to claim 1 or 2 wherein the battery module further comprises a duct which is fluidly connected to the chamber.

4. The battery module according to claim 3 wherein the duct is fluidly connected to the chamber below a surface of the liquid, so that at least some of the liquid is located in the duct.

5. The battery module according to claim 4 wherein sensor assembly comprises, a spring member which has a first end which is fixed and a second opposite end which is a free end; a stopper member which is attached to the free end of the spring and is located within the duct to block the flow of liquid through the duct; and wherein spring member biases the stopper member against the liquid in the duct; a first contact which is located along the duct, and which is configured to send a first signal to a controller when the stopper member reaches a first predefined trigger position along the duct.

6. The battery module according to claim 5 wherein sensor assembly further comprises a second contact which is located along the duct, and which is configured to send a second signal to a controller when the stopper member reaches a second predefined trigger position along the duct.

7. The battery module according to claim 6 wherein the spring member is partially compressed by a force applied by the liquid in the duct to the stopper member, wherein the spring member is partially compressed by an amount to position the stopper member in the duct at a position wherein the first predefine position is located at a first side of the stopper member and the second predefined trigger position is located at a second opposite side of the stopper member.

8. The battery module according to claim 3 wherein the duct is fluidly connected to the chamber above a surface of the liquid; so that at least some air and / or gas from inside chamber is located in the duct.

9. The battery module according to claim 8 wherein sensor assembly comprises, a spring member which has a first end which is fixed and a second opposite end which is a free end; a stopper member which is attached to the free end of the spring and is located within the duct to block the flow of air and / or gas through the duct; and wherein spring member biases the stopper member against air and / or gas in the duct; a first contact which is located along the duct, and which is configured to send a first signal to a controller when the stopper member reaches a first predefined trigger position along the duct.

10. The battery module according to claim 9 wherein sensor assembly further comprises a second contact which is located along the duct, and which is configured to send a second signal to a controller when thestopper member reaches a second predefined trigger position along the duct.11.The battery module according to claim 10 wherein the spring member is partially compressed by a force applied by the air and / or gas in the duct to the stopper member, wherein the spring member is partially compressed by an amount to position the stopper member in the duct at a position wherein the first predefine position is located at a first side of the stopper member and the second predefined trigger position is located at a second opposite side of the stopper member.

12. The battery module according any one of claims 6-11, wherein the plurality of battery cells comprise one or more pouch cells; and wherein the sensor assembly further comprising a third contact which is located along the duct, between the first and second contacts, and which is configured to send a third signal to a controller when the stopper member reaches a third predefined trigger position along the duct; and wherein the third signal indicates that a volume of one or more of the pouch cells has increased by an amount which is equal to, or greater than, a predefined threshold volume expansion.

13. The battery module according to any one of claims 3-12 further comprising an exhaust channel which is connected to the duct; and wherein the stopper member is located between the exhaust channel and the chamber so that the stopper member blocks the flow of fluid from the chamber and into the exhaust channel until the spring member has been compressed an amount sufficient to move the stopper member to a second position in which the stopper member is no longer between the exhaust channel and the chamber and fluid can flow from the chamber into the exhaust channel.

14. The battery module according to claim 13, wherein a junction between the duct and the exhaust channel is located on the first side of the stopper member, and wherein the junction between the duct and the exhaustchannel is located further away from the stopper member than the first predefined trigger position, so that the stopper member will reach the first predefined trigger position before reaching the second position in which fluid can flow from the chamber into the exhaust channel.

15. The battery module according to any one of the preceding claims further comprising a filler material.

16. The battery module according to claim 15 wherein the filler material comprises synthetic porous material.

17. The battery module according to any one of the preceding claims wherein the liquid changes phase from a liquid to gas at a temperature between 50 °C -120°C.

18. The battery module according to any one of the preceding claims wherein the liquid comprises a dielectric and / or comprises a thermally conductive fluid.

19. The battery module according to claim 18 wherein the liquid comprises a perfluoropolyether fluorinated fluid.

20. The battery module according to any one of the preceding claims wherein the liquid further comprises a solid material mixed in the liquid, wherein the solid material is composed of a phase change material.21.A battery module according to any one of the preceding claims further comprising a thermally conductive material which is positioned between the plurality of battery cells and the liquid, so as to facilitate the transfer of thermal energy from the plurality of battery cells to the liquid.

22. A battery module according to any one of the preceding claims further comprising a shield member which is arranged to overlay positive poles of the battery modules.

23. A battery module according to any one of the preceding claims wherein the plurality of battery cells are arranged within the chamber so that the negative electric pole of each respective battery cell is facing in a direction which is towards the liquid.

24. A battery module according to any one of claims 1-22 wherein the plurality of battery cells are arranged within the chamber so that the positive electric pole of each respective battery cell is facing in a direction which is towards the liquid.

25. A battery module according to any one of claims 1-22 wherein the plurality of battery cells are arranged within the chamber so the positive electric pole of each respective battery cell is below a surface of the liquid in the chamber.

26. A battery module according to any one of the preceding claims further comprising carbon nanotubes which are arranged to conduct heat away from the plurality of battery cells.

27. The battery module according to claim 26 wherein the carbon nanotubes are located inside the chamber and are attached to the battery cells.

28. The battery module according to claim 26 further comprising a plurality of sleeves located inside the chamber, and wherein each respective battery cells is positioned within a respective sleeve; and wherein the carbon nanotubes are attached to the sleeves.

29. The battery module according to any one of claims 26-28 wherein at least some of the carbon nanotubes are at least partially submerged in the liquid.

30. A battery module according to any one of the preceding claims further comprising carbon nanotubes which are attached to an outside of the chamber to conduct heat away from the chamber.

31. A battery module according to any one of claim 26-30 wherein the carbon nanotubes are in the form of one or more layers of carbon nanotubes.

32. A battery module according to claim 31 wherein the one or more layers of carbon nanotubes are each arranged on a plane which is perpendicular to longitudinal axes of each of each respective battery cells, so that heat is conducted away from the plurality of battery cells in a direction which is parallel to the longitudinal axes of the battery cells.

33. A battery module according to claim 31 or 32 wherein one or more layers of carbon nanotubes further comprise interface material, wherein each of the one or more layers carbon nanotubes is secured within the battery module via the interface material.

34. A battery module according to any one of claims 26-33 wherein the one or more channels are defined between carbon nanotubes.

35. A battery module according to any one of claims 26-34 wherein the carbon nanotubes each have a length between 1 mm-1cm.

36. An electric or hybrid vehicle comprising a battery module according to anyone of claims 1-35.

37. A battery module, comprising, a housing; a plurality of battery cells, arranged within said housing; and carbon nanotubes which is arranged to conduct heat away from the plurality of battery cells.

38. An electric or hybrid vehicle comprising a battery module according to claim 37.

39. A method of cooling one or more battery cells in a battery module which comprises a housing and a plurality of battery cells arranged within said housing, the method comprising the step of, using carbon nanotubes to conduct heat away from one or more of said battery cells.

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