A battery module

Abstract

A battery module (1111) which comprises, a plurality of battery cells (19); and at least one heat absorbing member (1112) which is arranged to be in thermal communication with the plurality of battery cells, and wherein the at least one heat absorbing member (1112) comprises heat absorbing material (1115) comprises a material which can undergo a phase change when heated. There is further provided an electric vehicle which comprises said battery module.

Description

A battery moduleField of Disclosure

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

[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.

[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] In view of these challenges, attempts to make electric and hybrid aircraft commercially viable have been largely unsuccessful. New approaches for making and operating electric and hybrid aircraft thus continue to be desired.Summary

[0007] Flying an aircraft, such as an airplane, can be dangerous. Problems with the aircraft may result in injury or loss of life for passengers in the aircraft or individuals on the ground, as well as damage to goods being transported by the aircraft or other items around the aircraft.

[0008] In order to attempt to mitigate potential problems associated with an aircraft, numerous organizations have developed certification standards for ensuring that aircraft designs and operations satisfy threshold safety requirements. The certification standards may be stringent and onerous when the degree of safety risk is high, and the certification standards may be easier and more flexible when the degree of safety risk is low.

[0009] Such certification standards have unfortunately had the effect of slowing commercial adoption and production of electric or hybrid aircraft. Electric or hybrid aircraft may, for example, utilize new aircraft designs relative to traditional aircraft designs to account for differences in operations of electric or hybrid aircraft versus traditional aircraft. The new designs however may be significantly different from the traditional aircraft designs. These differences may subject the new designs to extensive testingprior to certification. The need for extensive testing can take many resources, time and significantly drive up the ultimate cost of the aircraft.

[0010] The present disclosure provides simplified, yet robust, components and systems for an electric powered aircraft that simplify and streamline certifications requirements and reduce the cost and time required to produce a commercially viable electrically-driven aircraft.

[0011] In particular, powering an electric or hybrid aircraft can pose significant difficulties. Existing power systems used in electric or hybrid aircrafts tend to be heavy weight and large volume. For example, existing power systems include a battery module which comprises, a plurality of battery cells each having a first end and a second opposite end; a PCB located opposite the first end of the battery cells; and a first conductive plate, located opposite the first end of the battery cells, and which is electrically connected to a first electric pole of each respective battery cell; and a second conductive plate, located opposite the second end of the battery cells, which is connected to a second electric pole of each respective battery cell. Accordingly existing battery modules, the first and second conductive plates are located at opposite ends of the battery cells. Because first and second conductive plates are positioned at opposite ends of the battery cells, long conductive wires, which extend from the PCB to the other side of the battery cell, are used in order to electrically connect the second conductive plate to the PCB. These long conductive wires increase the weight of the battery module.

[0012] Additionally, since the first and second conductive plates are located at opposite ends of the battery cells in existing battery modules, each of the first and second conductive plates may include their own respective protective covering; in other words, in existing battery modules a first protective cover is provided at the first end of the battery cells to protect the first conductive plate, an a second protective cover is provided at the second end of the battery cells to protect the second conductiveplate; the use of two protective covers further increase the weight of the battery module.

[0013] Furthermore, since the first and second conductive plates are located at opposite ends of the battery cells, existing battery modules used in existing power systems use respective exhaust channels provided at opposite ends of the battery cells. In existing battery modules a first exhaust channel is provided opposite one end of the battery cells and a second exhaust channel is provided opposite the other end of the battery cells. The use of two exhaust channels will also further increase the weight of the battery module.

[0014] Positioning the first and second conductive plates, along with respective protective covers, and respective exhaust channels at opposite each of the battery cells, increases the volume of the battery module.

[0015] Moreover, having the first and second conductive plates located at opposite ends of the battery cells makes the manufacturing process of the battery module complex and expensive to provide access to the battery cells from both the top and the bottom of the battery module during manufacture.

[0016] Furthermore, some components of existing power systems are expensive to produce; for example, in existing battery modules spacers are provided between the battery cells; each of these spacers should be milled individually, leading to an increase in production costs.

[0017] Additionally, the fire safety of existing battery modules used in existing power systems is inadequate; for example, in existing battery modules: there is a high risk of battery cells over heating due to inadequate cooling; there is a high risk that when a battery cell catches fire that it goes into thermal runaway; there is a high risk that when a battery goes into thermal runaway that it burns or explodes; there is a high risk that the thermal runaway in a battery cell can cause a chain reaction of thermalrunaways in other battery cells in the battery module; and / or there is a risk of battery cells being projected from the battery modules in case of a fire or thermal runaway. Additionally cooling systems in existing battery modules can compromise electronic components in the battery module (e.g. particles or dirty in air flow provided by cooling systems can damage electronic components in the battery module).

[0018] It is an aim of the present disclosure to provide a solution to one or more of the above-mentioned problems of the prior art.

[0019] In particular, an aim of an aspect of the present disclosure is to provide a battery module for use in powering an electric vehicle, such as an electric aircraft, which is lighter, has reduced volume, and is less costly to produce. An aim of another aspect of the present disclosure is to provide a battery module which has improved fire safety and / or reduced risk of thermal runaway and / or reduces the impact of a thermal runaway. An aim of another aspect of the present disclosure is to provide a battery module which ensures that electronic components in the battery module are less susceptible to damage by the cooling system.

[0020] According to a first aspect of the present disclosure there is provided a battery module, comprising, a housing; a plurality of battery cells arranged in parallel within said housing, each battery cell having a first electric pole and a second electric pole, and each battery cell having a first end and a second opposite end; a conductive layer comprising at least a first conductive plate and a second conductive plate, wherein the first conductive plate is wire- bonded to the first electric poles of all the battery cells, so that the first conductive plate can conduct currents from the first electric poles of all battery cells, and wherein the second conductive plate is wire-bonded to the second electric poles of all the battery cells, so that the second conductive plate can conduct currents from the second electric poles of all battery cells; andwherein said at least first conductive plate and second conductive plate are located at the first end of the battery cells.

[0021] In the present disclosure since the at least first conductive plate and second conductive plate are located on the same end of the battery cells it eliminates the need to have long conductive wires which extend from the first end of the battery cells to the second opposite end of the battery cells, thereby reducing the weight and volume of the battery module.

[0022] Also, since the at least first conductive plate and second conductive plate are located on the same end of the battery cells it eliminates the need to have two protective covers and / or two exhaust channels, provided at opposite the ends of the battery cells, thereby further reducing the weight and volume of the battery module. For example, in the present disclosure a single protective cover located at the first end of the battery cells will serve to protect both the first and second conductive plates; likewise, only a single exhaust channel located at the first end of the battery cells may be necessary to achieve sufficient venting (e.g. venting of flames or fumes in case of fire).

[0023] Furthermore, since the at least first conductive plate and second conductive plate are located on the same end of the battery cells, this eliminates the need to be able to access the battery cells from both the top and the bottom of the battery module during manufacture; in the present disclosure, because the at least first conductive plate and second conductive plate are located at the first end of the battery cells, access only to the first end of the battery cells on which first and said second conductive plates are located may be necessary in order to perform the manufacturing steps. This makes the manufacturing process less complex and less expensive.

[0024] It should be understood that the above-mentioned battery module according to the first aspect of the present disclosure, may have any of the features of any of the embodiments described in the presentdisclosure. For example, the mentioned battery module according to the first aspect of the present disclosure, may have any of the features of any of the embodiments of the battery modules according to the second, third, fourth, and / or fifth aspects of the present disclosure.

[0025] According to a second aspect of the disclosure there is provided a battery module comprising: a housing configured to contain a plurality of battery sleeves, each battery sleeve accommodating one battery cell, each of the plurality of battery cells having a first terminal and a second terminal; at least a first conductive plate and second conductive plate; a first plurality of wire bonding electrically connecting a first terminal of the plurality of battery cells to the first conductive plate; and a second plurality of wire bonding electrically connecting the second terminals of the plurality of battery cells to the second conductive plate; and intumescent material positioned around each of the battery sleeves.

[0026] It should be understood that the above-mentioned battery module according to the second aspect of the present disclosure, may have any of the features of any of the embodiments described in the present disclosure. For example, the mentioned battery module according to the second aspect of the present disclosure, may have any of the features of any of the embodiments of the battery modules according to the first, third, fourth, and / or fifth aspects of the present disclosure.

[0027] Notably in this second aspect of the disclosure the position of the at least first conductive plate and second conductive plate is not limited; for example the at least first conductive plate and second conductive plate may be located at opposite ends of the battery cells (i.e. the first conductive plate located at one end of the battery cells, and the second conductive plate located at the second opposite end of the battery cells), or, the atleast first conductive plate and second conductive plate may be located at the same end of the battery cells.

[0028] The intumescent material transmits heat up until a predefined temperature threshold and then burns or reacts at temperatures above that threshold, and acts as an insulator after burning or reacting. So, advantageously in said second aspect of the present disclosure, the intumescent material will transmit heat generated by the battery cells in the battery module, during normal use, thereby allowing cooling the battery cell through the intumescent material and reducing the risk of the battery cells catching fire; but if / when any one or more of the battery cells goes into thermal runaway the heat generated by the thermal runaway will exceed the predefined temperature threshold causing the intumescent material to burn or react and act as an insulator which prevents the heat from the thermal runaway from spreading to other battery cells in the battery module. In this way the intumescent material can reduce the risk of a chain reaction of thermal runaways occurring in the battery cells of the battery module.

[0029] The intumescent material is outside of the battery sleeves, so that the heat from the battery cell is directly transmitted to the battery sleeve. The battery sleeve may be made of a heat transmitting material, preferably metal such as aluminium.

[0030] Having the intumescent material outside of the battery cell allows for a larger expansion of the intumescent material when the intumescent material burns or reacts.

[0031] According to a third aspect of the present disclosure there is provided a battery module comprising: a housing configured to contain a plurality of battery cells, each of the plurality of battery cells having a first terminal and a second terminal; at least a first conductive plate and second conductive plate;a first plurality of wire bonding electrically connecting a first terminal of the plurality of battery cells to the first conductive plate; and a second plurality of wire bonding electrically connecting the second terminals of the plurality of battery cells to the second conductive plate; a fire shield element which is configured to define an exhaust channel; a PCB located at a first side of the fire shield, and wherein the plurality of battery cells are located at a second opposite side of the fire shield, so that the fire shield is located between the PCB and the plurality of battery cells; and a cooling means which is arranged to provide a cooling fluid (such as an air flow for example) which can cool the plurality of battery cells, and wherein said cooling means is also located at said second opposite side of the fire shield element, and wherein the fire shield element is configured to be impermeable to the cooling fluid provided by the cooling means.

[0032] It should be understood that the above-mentioned battery module according to the third aspect of the present disclosure, may have any of the features of any of the embodiments described in the present disclosure. For example, the mentioned battery module according to the third aspect of the present disclosure, may have any of the features of any of the embodiments of the battery modules according to the first, second, fourth, and / or fifth aspects of the present disclosure.

[0033] Notably in this third aspect of the disclosure the position of the at least first conductive plate and second conductive plate is not limited; for example the at least first conductive plate and second conductive plate may be located at opposite ends of the battery cells (i.e. the first conductive plate located at one end of the battery cells, and the second conductive plate located at the second opposite end of the battery cells), or, the at least first conductive plate and second conductive plate may be located at the same end of the battery cells. Also, notably in this third aspect of thedisclosure the battery module may or may not further comprise intumescent material.

[0034] Advantageously in the third aspect of the present disclosure the cooling means can be selectively activated to provide a cooling fluid to cool the battery cells in the battery module. Because the fire shield element is impermeable to the cooling fluid provided by the cooling means, and because the cooling means and PCB are located at opposite sides of the fire shield element, the cooling fluid provided by the cooling means is blocked by the fire shield element from passing over the PCB. This will ensure that electronic components on the PCB are protected against dirt or residue that may be in said cooling fluid. The cooling fluid will preferably pass over the battery cells and into exhaust channel for emitting into the atmosphere.

[0035] Preferably the battery module further comprise a flexible PCB also located at said second opposite side of the fire shield element. Preferably the cooling means is arranged so that the cooling fluid (such as an air flow for example) flows from below the battery cells towards the exhaust channel which is located above the battery cells. Preferably the cooling means comprises one or more fans which are selectively operable to generate an air flow which can cool the batter cells. Preferably the exhaust channel is perpendicular to the longitudinal axis of the battery cells, so that when the cooling fluid flows through the exhaust channel it will flow in a direction which is perpendicular to direction of the flow from the first end of the battery cells to a second opposite end of the battery cells.

[0036] It should be understood that any one of the above-mentioned first, second or third aspects of the present disclosure, may have any one or more of the features of any of the other first, second or third aspects of the present disclosure.

[0037] It should be understood that any of the subsequently described features may be optional features of any of the above mentioned first, second and / or third aspects of the present disclosure. Even if a feature isdescribed in the present application as being a feature of one of said above-mentioned aspects, it should be understood that that feature could be an optional feature of any of the other aspects of the present disclosure.

[0038] According to a fourth aspect of the present disclosure there is provided a battery module which comprises, a plurality of battery cells; and a cooling system which comprises at least one inlet and at least one outlet, and a cooling duct along which a cooling fluid can flow, and wherein the cooling duct is fluidly connected between the at least one inlet and at least one outlet.

[0039] It should be understood that the above-mentioned battery module according to the fourth aspect of the present disclosure, may have any of the features of any of the embodiments described in the present disclosure. For example, the mentioned battery module according to the fourth aspect of the present disclosure, may have any of the features of any of the embodiments of the battery modules according to the first, second, third, and / or fifth aspects of the present disclosure.

[0040] According to a fifth aspect of the present disclosure there is provided a battery module which comprises, a plurality of battery cells; and at least one heat absorbing member which is arranged to be in thermal communication with the plurality of battery cells, and wherein the wherein the at least one heat absorbing member comprises heat absorbing material comprises a material which can undergo a phase change when heated.

[0041] It should be understood that the above-mentioned battery module according to the fifth aspect of the present disclosure, may have any of the features of any of the embodiments described in the present disclosure. For example, the mentioned battery module according to the fifth aspect of the present disclosure, may have any of the features of any of the embodiments of the battery modules according to the first, second, third, and / or fourth aspects of the present disclosure.Optional features that aof thedisclosure can have, are as follows:

[0042] Optionally, each of the battery cells in the battery module may be held within a respective sleeve which is closed at one end.

[0043] Each battery cell may be fixed to the respective sleeve in which it is held; preferably each battery cell is fixed, by glue or welding, to the respective sleeve in which it is held (preferably each battery cell is glued to a closed end of its respective sleeve). Advantageously, having each battery fixed to a respective sleeve which is closed at one end, will reduce the risk of a battery cell being projected from the battery module in the event of a thermal runaway. In a preferred embodiment each battery module is glued to its respective sleeve by means of an electrically conductive glue.

[0044] Furthermore, in a preferred embodiment of the present disclosure, each respective sleeve which holds a battery cell has a shoulder portion which allows the sleeve to be held in a battery cell holder; this eliminates the need for individually milled spacers to achieve a fixed relative positioning of the battery cells. The elimination of spacers makes the manufacturing process less complex and less expensive. The shoulder may further strengthen the battery sleeve.

[0045] In an embodiment the at least first conductive plate and second conductive plate are coplanar.

[0046] It should be understood that the conductive layer may comprise any number of conductive plates greater than or equal to '2'. In an embodiment the conductive layer comprises more than '2' conductive plates. Preferably, all of the conductive plates in the conductive layer are located at the same end (i.e. the first end) of the battery cells.

[0047] Preferably all of the conductive plates in the conductive layer are arranged to occupy the same plane; and preferably each of the conductive plates occupy a different respective position on said plane so that the conductive plates are mechanically independent of one another, and preferably no conductive plate partially overlaps, or fully overlaps, another conductive plate.

[0048] Preferably the plurality of conductive plates of the conductive layer are each shaped complementary to one another to allow the conductive plates to be arranged to occupy the same plane, and to occupy a different respective position on said plane. In an embodiment the plurality of conductive are shaped so that they can be arranged in an interdigital or interdigitated arrangement.

[0049] In an embodiment the at least first conductive plate is electrically connected to respective first poles of all each respective battery cell in the battery module, and the at least second conductive plate is electrically connected to respective second poles of each respective battery cell in the battery module. In an embodiment wherein the conductive layer comprises more than two conductive plates, a first conductive plate is electrically connected to the first poles of some of the battery cells in the battery module, and at least a second conductive plate that is electrically connected to the first poles of some other of the battery cells that the first conductive plate is not connected to, and at least a third conductive plate that is electrically connected to the second poles of the battery cells in the battery module. Preferably the first pole of a battery cell is the positive pole, and the second pole of the battery cell is the negative pole.

[0050] In a preferred embodiment the at least first conductive plate is electrically connected (preferably by wire bonding) to the second pole (negative pole) of the battery cells in the battery module. For example, in an embodiment the at least first conductive plate is electrically connected to an outer surface of each battery cell, wherein the outer surface of each battery cell is electrically connected to the second pole (the negative pole)of that battery cell. In a preferred embodiment each battery cell is electrically connected to a respective sleeve within which it is held; more preferably the negative pole of the battery cell is electrically connected to the sleeve, and that same negative pole is electrically connected to a conductive plate in the conductive layer. In an embodiment each battery cell is electrically connected to the sleeve in which it is held by means of a conductive glue which electrically connects the negative pole of the battery cell to the sleeve; the conductive glue will also serve to hold the battery cell within that sleeve.

[0051] The battery module may comprise a laminated top plate. In an embodiment the laminated top plate comprises, a substrate which comprises a top substrate layer and a bottom substrate layer; a flex PCB; and the conductive layer (which is comprises said at least a first and second conductive plates).

[0052] Preferably the flex PCB and the conductive layer, are sandwiched between the top substrate layer and a bottom substrate layer.

[0053] In an embodiment the battery module further comprises a plurality of sleeves, each sleeve holding a respective battery cell. In another embodiment the battery module is without any sleeves.

[0054] The battery module may further comprise a battery cell holder. Preferably the battery cell holder is mounted on a top surface of the housing. Preferably the battery cell holder is located below the laminated top plate.

[0055] In an embodiment the battery cell holder is configured to be modular. In an embodiment the battery cell holder comprises a main support platform having a plurality of sockets defined therein; and a plurality of battery cell holder plates, which can be selectively inserted into and held within a respective socket in the main support platform.Preferably each battery cell holder plate has plurality of through-holesdefined therein each of which can receive a respective battery cell or receive a respective sleeve within which a battery cell is accommodated.

[0056] In one embodiment each of the battery cells are held within a respective sleeve, and the battery cell holder is configured to hold a plurality of said sleeves. In another embodiment the battery module is without sleeves, and the battery cell holder is configured to directly hold the plurality of battery cells.

[0057] In an embodiment the battery module further comprises a fire shield element. Preferably the fire shield element defines an exhaust channel through which flames and / or fumes and / or ejecta can pass. Preferably the fire shield element is mounted above the laminated top plate. Preferably the fire shield element is composed of inflammable material.

[0058] Preferably the battery module comprises a single exhaust channel. Preferably the single exhaust channel is located at one end of the battery modules (preferably located above the laminated top plate so that the laminated top plate is interposed between the battery modules and the exhaust channel).

[0059] Preferably the laminated top plate is located between the fire shield element and the battery cell holder.

[0060] In a preferred embodiment the laminated top plate has a plurality of through-holes defined therein. If a battery cell catches fire, or explodes, then fumes and / or flames from the fire or explosion, can be vented through the through-holes in the laminated top plate and into the exhaust channel defined by the fire shield element.

[0061] In an embodiment the top substrate layer of the laminated top plate further comprises a plurality of secondary through-holes definedtherein. Preferably portions of the conductive plates in the conductive layer are exposed through the secondary through-holes in the top substrate layer.

[0062] Preferably electrically conductive wires, which are electrically connected at one end thereof to the battery cells, are arranged to extend through the through-holes in the laminated top plate, and through the secondary through-holes defined in the top substrate layer, to be connected at the other end thereof to a conductive plate of the conductive layer.

[0063] In an embodiment the bottom substrate layer has a plurality of through-holes defined therein. The flex PCB preferably comprises connecting portions that are arranged to extend through the through- holes in the bottom substrate layer. In a preferred embodiment, a respective sensor, such as a temperature sensor, is mounted onto each respective connecting portion and each temperature sensor is arranged such that it can measure the temperature of a respective battery cell.

[0064] In an embodiment one or more switches are provided onto the flex PCB. The switched may be used for selectively disconnecting each respective battery cell, for example in case of over-temperature, overcurrent, over-voltage, over-pressure and / or other malfunctions of the battery cell.

[0065] In an embodiment the battery module further comprises a PCB. Preferably the PCB is mounted on an outer surface of the fire shield element.

[0066] In an embodiment the battery module further comprises a cover. In an embodiment, the cover is configured to provide protection to the PCB. Preferably, the cover is mounted on the on the outer surface of the fire shield element, and the PCB is located within a volume defined by the cover and the outer surface of the fire shield element.

[0067] In an embodiment the battery module further comprises a plurality of sleeves each of which is configured to accommodate a respective battery cell. The sleeves will provide some protection to the battery cell it accommodates, against mechanical shocks, heat, humidity, and other hazards.

[0068] In a preferred embodiment each sleeve is composed of a heat conductive and / or electrically conductive material. Having the sleeve composed of heat conducting material enables the sleeve to conduct heat away from the battery cell which it holds, thereby decreasing the risk of the battery cell catching fire.

[0069] In an embodiment each sleeve has an open end and a closed end. For example, each sleeve has an open top end and a closed bottom end.

[0070] In an embodiment each sleeve comprises a shoulder portion. The shoulder portion may provide some strength and rigidity to the sleeve; any may also be used to support the sleeve in a battery cell holder.

[0071] Preferably each battery cell is glued or welded to the respective sleeve in which it is accommodated. The glue or weld will serve to hold the battery cell in the sleeve; advantageously this will reduce the possibility of the battery cell being projected from the sleeve in case of an explosion or fire, thereby improving the safety of the battery module. The glue may be an electrically conductive glue for example; electrically conductive glue many not only serve to hold the battery cell in the sleeve, but may also be used to electrically connect the negative pole of the battery cell to the sleeve.

[0072] In an embodiment the battery module comprises one or more sensors. For example, the battery module may comprise any one or more of, an infrared sensor (e.g. an infrared sensor which may be configured to measure the heat of one or more of the battery cells), a pressure sensor (e.g. a sensor for measuring an internal pressure of each or the plurality ofbattery cells), a thermocouple sensor, a hydrogen sensor, a light sensor, a voltage sensor, a current sensor. One or more of said sensors may be mounted on the flex PCB. In preferred embodiment an infrared sensor and / or a hydrogen sensor and / or a pressure sensor and / or a light sensor, is located above the laminated top plate (e.g. an infrared sensor and / or a hydrogen sensor and / or a pressure sensor and / or a light sensor, may be mounted on the PCB which is located between the laminated top plate and the fire shield); in this location the infrared sensor can, for example, sense heat generated with a battery cell catches fire.

[0073] In an embodiment the battery module may further comprise intumescent material. Preferably the intumescent material is positioned outside each of each battery cell (e.g. it arranged to surround each battery cell). For example, a layer, or coating, of intumescent material may be arranged around each respective battery cell. In an embodiment the intumescent material is arranged to abut each respective battery cell. In an embodiment in which each battery cell is accommodated within a respective sleeve, the intumescent material may be positioned outside each sleeve (e.g. it arranged to surround each sleeve). For example, a layer, or coating, of intumescent material may be arranged around each respective sleeve. In an embodiment the intumescent material is arranged to abut each respective sleeve.

[0074] The thickness of the intumescent material may be in the range 0,2mm-0.5mm.

[0075] Preferably the intumescent material has a composition which will ensure that the intumescent material reacts, or burns, when it reaches a temperature which is equal to, or greater than, 130°C. Once the intumescent material has reacted, or burned, the reacted or burned intumescent material will act as an insulator. In an embodiment the intumescent material comprises on-flammable material. In an embodiment the intumescent material has a composition such that when it is heated (preferably heated above a predefined temperature) it releases water orother fluids that vaporize, which in turn create porosity in the intumescent material.

[0076] In an embodiment the battery module may further comprise foam material (such as metal foam). The foam material is preferably porous. Advantageously the foam material can increase the effective surface area from which heat can be dissipated. Preferably the foam material comprises metal. Preferably the foam material is positioned outside each of each battery cell (e.g. it arranged to surround each battery cell). For example, a layer, or coating, of foam material may be arranged around each respective battery cell. In an embodiment foam material is arranged to abut each respective battery cell.

[0077] In an embodiment in which each battery cell is accommodated within a respective sleeve, the foam material may be positioned outside each sleeve (e.g. it arranged to surround each sleeve). For example, a layer, or coating, of foam material may be arranged around each respective sleeve. In an embodiment foam material is arranged to abut each sleeve.

[0078] In an embodiment intumescent material may be encapsulated in said foam material. Advantageously this embodiment achieves improved heat dissipation which reduces the risk of overheating of a battery cell and of thermal runaway of the battery cell; and in the event a thermal runaway of a battery cell should occur, improved containment of the heat of the thermal runaway is achieved thereby reducing the risk of a chain reaction of thermal runaways in the other battery cells in the battery module.

[0079] In an embodiment the battery module may further comprise phase change material. Preferably the phase change material is positioned outside each of each battery cell (e.g. it arranged to surround each battery cell). For example, a layer, or coating, of phase change material may be arranged around each respective battery cell. In an embodiment the phase change material is arranged to abut each respective battery cell. In an embodiment in which each battery cell is accommodated within arespective sleeve, the phase change material may be positioned outside each sleeve (e.g. it arranged to surround each sleeve). For example, a layer, or coating, of phase change material may be arranged around each respective sleeve. In an embodiment the phase change material is arranged to abut each respective sleeve.

[0080] In an embodiment the phase change material may be encapsulated in the foam material.

[0081] In an embodiment the foam material comprises both the phase change material and intumescent material. Preferably the phase change material and intumescent material are each encapsulated in the foam material.

[0082] In an embodiment phase change material may also, or additionally, be provided in the form of pouches which are arranged between the battery cells. In an embodiment wherein each battery cell is accommodated in a respective sleeve, the phase change material may be provided in the form of pouches which are arranged between the respective sleeves.

[0083] The phase change material may take any suitable form and many have any suitable composition. For example, the phase change material may be in the form of a solid which changes phase into a liquid when heated; or the phase change material may be in the form of a liquid which changes phase into a gas when heated. In the afore-mentioned examples the phase change material undergoes one phase change when heated, however, in another embodiment the phase change material may undergo two phase changes when heated; for example, the phase change material may be in the form of a solid which changes phase into a liquid when heated, and the liquid subsequently changes phase into a gas when heated.

[0084] In an embodiment wherein each battery cell is accommodated in a respective sleeve, in each sleeve a thermal conductive material is locatedbetween the battery cell and the sleeve. For example in each sleeve a thermal conductive material is located between an outer surface of the battery cell and an inner surface of the sleeve. The thermal conductive material will serve to conduct heat generated by the battery cell, away from the battery cell and into the sleeve. Preferably, in this embodiment, a layer of foam material is further positioned outside of each sleeve (e.g. for each sleeve, a layer or foam material abuts the outer surface of the sleeve). Preferably, in this embodiment, a layer intumescent material is further positioned outside the layer of foam material. For example, the intumescent material may be provided as a coating on the layer of foam material.

[0085] It should be understood that any embodiment of the disclosure may comprise any one or more of: thermal conductive material, and / or foam material, and / or intumescent material, and / or phase change material.

[0086] In an embodiment of the present disclosure during normal use each of the battery cells will generate heat; for each battery cell, the heat generated by the battery cells can be conducted to the sleeve which accommodates that battery cell, via the thermal conductive material that may be located between the battery cell and inner surface of the sleeve. Heat from the sleeve may be further conducted into foam material (e.g. a layer of foam material) that may be positioned outside of the sleeve; since the foam material is porous the foam material will effectively increase the contact surface area between the sleeve and the air, thereby allowing for greater heat dissipation away from the sleeve. Intumescent material may be provided on the foam material, or incapsulated in the foam material; heat from the foam material will pass into intumescent material. Up until a predefined temperature threshold (e.g. 130°C) the layer of intumescent material will absorb the heat from the foam layer, thus keeping the battery cell cool; typically, during normal use, the battery cell will not generate enough heat which would cause the intumescent material to heat to above the predefined temperature threshold (e.g. 130°C).

[0087] However, in the case one or more of the battery cells in the battery module go into thermal runaway (e.g. explode), then the heat generated by the thermal runaway (e.g. explosion) will heat the intumescent material to a temperature which is above the predefined temperature threshold. When the intumescent material is heated above the predefined temperature threshold the intumescent material will react or burn, transforming from thermally conductive layer into a thermally insulative layer. In other words, below the predefined temperature threshold the intumescent material is thermally conductive (conducting heat away from the form layer), whereas above the predefined temperature threshold the intumescent material reacts, or burns, to become thermally insulative. The reacted or burnt intumescent material will act as an insulator which prevents the heat from the thermal runaway (e.g. explosion) from propagating to other battery cells in the battery module. In this way the intumescent material helps to contain at least some of the heat of the thermal runaway thereby reducing the risk of a thermal runaway in one battery cell causing a chain reaction of thermal runaways in the other battery cells in the battery module.

[0088] In an embodiment in which the battery module additionally comprises phase change material, or alternatively comprises phase change material, which for example is positioned outside each of the respective sleeves, then the heat generated by each respective battery cell during normal use will be absorbed by the phase change material. In the event one or more of the battery cells go into thermal runaway then the heat generated by the thermal runaway will heat the phase change material; the phase change material will consume heat energy from the thermal runaway undergoing one or more phase changes, thereby reducing the risk of a thermal runaway in one battery cell causing a chain reaction of thermal runaways in the other battery cells in the battery module.

[0089] Furthermore, any flames and / or fumes and / or ejecta, generated by the thermal runaway may pass through through-holes which are defined in the laminated top plate; the flames and / or fumes and / or ejecta may vent through the through holes and into the exhaust channel which is definedby the fire shield element. This exhaustion of flames and / or fumes and / or ejecta may help to prevent the spread of the fire to the other battery cells in the battery module. Any flames and / or fumes and / or ejecta that pass through the exhaust channel may be directed into the atmosphere for example.

[0090] In an embodiment the battery module may further comprise a cooling means which is operable to cool the battery cells in the battery module.

[0091] In an embodiment the cooling means may be located inside the housing; in another embodiment the cooling means may be located outside of the housing.

[0092] In a preferred embodiment the cooling means comprises a one or more fans. In a preferred embodiment the one or more fans are mounted on an outer surface of a side wall of the housing (i.e. the housing within which the battery modules are housed); and the side wall of the housing further comprise holes defined through which air flow generated by the one or more fans can pass into the housing to cool the battery cells. In this embodiment air flow will enter into the housing from the die of the housing. Advantageously locating the fans on the side wall of the housing helps to keep the vertical footprint of the battery module to a minimum. In another embodiment the fans are located below the battery cells. For example, in another embodiment the laminated top plate is located above the battery cells and one or more fans are located beneath the battery cells so that cooling is provided from below the battery cells.

[0093] Preferably the holes in the side wall of the housing are located adjacent to an end of the battery cells; preferably the holes are located adjacent to one end of the battery cell and the exhaust channel which is defined by the fire shield element is located at the other end of the battery cells; such positioning will ensure that the air flow generated by the fanswill pass over the full length of the battery cells, thereby maximizing the cooling effect.

[0094] Preferably the battery cells in the battery module are arranged in sets. For example, the battery cells in the battery module may be arranged in sets of '9' battery cells (arranged in a 3x3 arrangement) - the battery module will preferably comprise a plurality of sets of battery cells. In an embodiment the number of fans in the cooling means correspond to the number of sets of battery cells (i.e. there is one fan provided for each respective set). In another embodiment number of fans in the cooling means correspond to the number of battery cells (i.e. there is one fan provided for each battery cell). In an embodiment the number holes in the side wall of the housing correspond to the number of sets of battery cells. Advantageously, having respective individual fans to cool each respective set of battery cells (or to cool each individual battery cell) in the battery module, allows for more energy efficient cooling, as it allows to selectively cool only or specifically those battery cells with a temperature that exceeds the predefined temperature threshold.

[0095] In embodiment the battery module further comprises a plurality of temperature sensors, each temperature sensor being arranged to measure the temperature of a respective battery cell.

[0096] In embodiment the battery module further comprises a controller which is operably connected to each of the temperature sensors and to each of the one or more fans. The controller is configured to selectively operate one or more of the fans, based on temperature measurements that the controller receives from the temperature sensors, to maintain each of the battery cells in the battery module at a temperature that is within a predefined temperature range. Preferably the controller is configured to maintain the all of the battery cells in the battery module at a temperature within a predefined temperature range (e.g. between 30°C- 40°C). Advantageously, maintaining a battery cell within the predefined temperature range will ensure that the battery cell does not over-heat; thiswill ultimately extend the lifetime of that battery cell. Furthermore, maintaining all of the battery cells in the battery module within the predefined temperature range will ensure a more uniform lifetime of the battery cells within the battery module.

[0097] The controller may further comprise a memory which stores an ID of each temperature sensor and associated with each respective temperature sensor ID is an ID of a respective fan. These IDs will enable the controller to know which fan to operate if a temperature sensor indicates that the temperature of a battery cell is above a predefined threshold temperature.

[0098] In an embodiment the battery module further comprises at least one thermally conductive member which is arranged to be in thermal communication with a least one of the battery cells; and wherein the cooling duct is arranged to be in thermal communication with the thermally conductive member so that cooling fluid flowing in the cooling duct can absorb heat from the thermally conductive member.

[0099] In an embodiment the thermally conductive member comprises one or more foam sheets. In an embodiment the one or more foam sheets comprise, a metal and / or an alloy and / or carbon.

[0100] In an embodiment the battery module further comprises one or more fans which are fluidly connected to the at least one inlet, and which is selectively operable to provide a flow of cooling air along the cooling duct.

[0101] In an embodiment the battery module further comprises a pump means which is fluidly connected to the at least one inlet, and which is selectively operable to provide a flow of cooling fluid along the cooling duct.

[0102] In an embodiment the battery module further comprises a heat exchanger which is fluidly connected to the at least one outlet, and which is operable to recool cooling fluid that has passed through the cooling duct.

[0103] In an embodiment the at least one heat absorbing member, which is arranged to be in thermal communication with the plurality of battery cells, comprises an encapsulation element which holds said heat absorbing material.

[0104] In an embodiment the heat absorbing material comprises a material which can undergo a phase change when heated to a predefined temperature.

[0105] In an embodiment the encapsulation element comprises a matrix which holds the heat absorbing material. In an embodiment the heat absorbing material is impregnated into the matrix. In an embodiment the matrix comprises thermally conductive material.

[0106] In an embodiment the matrix comprises any one or more of: graphite, and / or aerogel, and / or non-woven carbon fiber, and / or glass fiber, and / or carbon, and / or carbon fiber, and / or metal, and / or metal alloy, and / or polymer.

[0107] In an embodiment the encapsulation element further comprises a casing and wherein the matrix is held within a volume defined by the casing.

[0108] In an embodiment the heat absorbing material is further provided outside of the matrix within the volume defined by the casing.

[0109] In an embodiment the casing comprises thermally conductive material

[0110] In an embodiment the casing comprises any one or more of: aluminum-polymer laminates, and / or non-flammable and / or watertight cloth such as fiber-reinforced polymers.

[0111] In an embodiment the encapsulation element comprises a plurality of pouches each of which hold the heat absorbing material. In an embodiment each pouch is air-tight.

[0112] In an embodiment the encapsulation element comprises thermally conductive material.

[0113] In an embodiment the encapsulation element comprises any one or more of: aluminum-polymer laminates, and / or non-flammable and / or watertight cloth such as fiber-reinforced polymers.

[0114] In an embodiment the heat absorbing material further comprises a gelling agent and / or a thickening agent. The gelling agent and / or a thickening agent may take any suitable form; the gelling agent and / or a thickening agent is any agent that can increase viscosity of a liquid. A rheology modifier is just one example of a possible gelling agent and / or a thickening agent.

[0115] In an embodiment the heat absorbing material is liquid-based.

[0116] In an embodiment the heat absorbing material is aqueous-based.

[0117] In an embodiment the heat absorbing material comprises any one or more of, water, and / or a water-based solution, sodium acetate trihydrate, iron sulfate heptahydrate and / or any other salt hydrates.

[0118] In an embodiment the battery module further comprises one or more compressible members which are arranged in the battery module toprevent movement of the battery cells within the battery module, an which are configured to be compressible by swelling of the battery cells.

[0119] In an embodiment the compressible members are arranged on either side of each battery cell so that each battery cell is flanked by compressible members.

[0120] In an embodiment each compressible member comprises a material which is compressible and thermally insulative.

[0121] In an embodiment the battery module further comprises a heat sink which is arranged to be in thermal communication with the at least one heat absorbing member.

[0122] Any of the battery module embodiments of the present disclosure may be used to power an electric vehicle, such as electric or hybrid aircrafts. Therefore, according to a further aspect of the present disclosure there is provided an electric vehicle which comprises a battery module according to any of the embodiments described in the present application. Preferably the electric vehicle is an electric aircraft, or a hybrid aircraft.Short Description of the Drawings

[0123] Exemplary embodiments of the disclosure are disclosed in the description and illustrated by the drawings in which:Fig. 1A illustrates an example aircraft, such as an electric or hybrid aircraft;Fig. 1 B illustrates airflow through the aircraft of Fig. 1 A;Fig. 1C illustrates a simplified block diagram of the aircraft of Fig. 1A;Fig. 2 illustrates an example operation system for an aircraft, such as the aircraft of Fig. 1A;Fig. 3a provides a perspective view of a battery module according to and embodiment of the present disclosure; Fig. 3b is a cross-sectional, perspective view of the battery module shown in Fig. 3a;Fig. 4 shows a perspective view of the conductive layer of the battery module;Fig. 5a shows a perspective view of the sleeves in the battery module; and Fig. 5b shows a longitudinal section view of a sleeve and battery cell held in that sleeve;Fig. 6 shows a perspective view of the battery cell holder of the battery module;Fig. 7 shows a perspective view of the flex PCB of the battery module;Fig. 8a shows a top view of the laminated top plate of the battery module; Fig. 8b shows a perspective view of the laminated top plate of the battery module;Fig. 9a provides a perspective view of a battery module according to an embodiment of the present disclosure; Fig. 9b is a cross-sectional view of the battery module shown in Fig. 9a;Figs. 10a-10g illustrate a battery module according to a further embodiment of the present disclosure;Fig. 11a illustrates a battery module according to a further embodiment of the present disclosure; Fig. 11 b illustrates a heat absorbing member, with a partial cut-away portion, which is used in the battery module of Fig 11a.Detailed Description of Exemplary Embodiments

[0124] Fig. 1A illustrates an aircraft 150, such as an electric or hybrid aircraft, and Fig. 1 B illustrates airflow 102 through the aircraft 150. The aircraft 150 has an aircraft housing 101. The aircraft can include power sources 104, inlets 106, exhausts 108, one or more water separators 114, and one or more filters 112. The inlets 106 can include inlet ports proximate to an exterior of the aircraft 150 and inlet channels extending from the inlet ports into the aircraft 150. The exhausts 108 can include exhaust ports proximate to the exterior of the aircraft 150 and exhaust channels extending from the exhaust ports into the aircraft 150.

[0125] During operation of the aircraft 150 or when the power sources 104 may be supplying power, the airflow 102 can flow into the aircraft 150 from one of the inlets 106 (which can be locations of relatively higher pressure), pass in or around one or more of the power sources 104, and next pass out one of the exhaust ports 108 (which can be locations of relatively lower pressure). The airflow 102 can cool the one or more the power sources 104 during normal operation or facilitate expulsion of heat or combustion components from the aircraft 150 in the event of a fire at the one or more of the power sources 104. The air of the airflow 102 can be filtered (for example, by one of the filters 112) as the air passes through the aircraft 150. Water or other impurities may be removed from the air (for example, by one of the one or more water separators 114) as the airflow 102 passes through the aircraft 150.

[0126] As described herein, the aircraft 150 can include an electric power system that includes integrated fire relief channels so that heat created by a fire or explosion of one of the power sources, such as thepower sources 104, may diverted through an exhaust channel to an exhaust, such as an exhaust port of the exhausts 108.

[0127] The aircraft 150 can include one or more components or features of aircrafts disclosed in (i) U.S. Patent No. 10,131,246, issued November 20, 2018, titled "COMMUNICATION SYSTEM FOR BATTERY MANAGEMENT SYSTEMS IN ELECTRIC OR HYBRID VEHICLES," (ii) U.S. Patent No. 10,322,824, issued June 18, 2019, titled "CONSTRUCTION AND OPERATION OF ELECTRIC OR HYBRID AIRCRAFT," the entire disclosures of which are hereby incorporated by reference.

[0128] Fig. 1C illustrates a simplified block diagram of an aircraft 150, which can be an implementation of the aircraft 150 of Fig. 1A. The aircraft 150 includes a motor 160, a management system 170, and a power source 180. The power source 180 can be an implementation of one or more of the power sources 104. The motor 160 can be used to propel the aircraft 150 and cause the aircraft 150 to fly and navigate. The management system 170 can control and monitor the components of the aircraft 150, such as the motor 160 and the power source 180. The power source 180 can power the motor 160 to drive the aircraft 150 and power the management system 170 to enable operations of the management system 170. The management system 170 can include one or more controllers as well as other electronic circuitry for controlling and monitoring the components of the aircraft 150.

[0129] The motor 160 can be or include an electrical motor, such as a DC motor, a one phase AC motor, or a three phase AC motor. The motor 160 can include an electric brushless motor. The motor 160 can include more than one motor. The motor 160 can move the aircraft 150 and drive a (thrust-generating) propeller or a (lift-generating) rotor. The motor 160 can function as a generator. The motor 160 can include multiple motors, such as electric motors. The aircraft 150 can include one or a plurality of electric motors and, optionally, one or a plurality of thermic motors, and function as a pure electric airplane or as a hybrid airplane.

[0130] The power source 180 can store electrical energy and include, as disclosed herein, one or more battery modules that each include one or more battery cells. The battery cells of a battery module may be electrically connected in series and / or parallel with one another to deliver a desired voltage and current from the battery module. Two or more battery modules can be electrically connected in series and / or in parallel to form a battery pack and deliver a desired voltage and current from the two or more battery modules. The aircraft can comprise two or more battery packs as power source. The battery cells can be lithium-ion (Li-Ion) battery cells or lithium-polymer (Li-Po) battery cells.

[0131] Fig. 2 illustrates an operation system 200 of an aircraft, such as the aircraft 150 of Figs. 1A, 1 B, and 1C. The operation system 200 can include a power management system 210, a motor management system 220, and a recorder 230, as well as a first battery pack 212A, a second battery pack 212B, a warning panel 214, a fuse and relay 216, a converter 217, a cockpit battery pack 218, a motor controller 222, one or more motors 224, and a throttle 226. The one or more motors 224 can be an implementation of the motor 160, the first battery pack 212A and the second battery pack 212B can be an implementation of the power sources 104 or the power source 180, and the remaining components can be an implementation of the management system 170.

[0132] The power management system 210, the motor management system 220, and the recorder 230 can monitor communications on a communication bus, such as a controller area network (CAN) bus, and communicate via the communication bus. The first battery pack 212A and the second battery pack 212B can, for instance, communicate on the communication bus enabling the power management system 210 to monitor and control the first battery pack 212A and the second battery pack 212B. As another example, the motor controller 222 can communicate on the communication bus with the motor management system 220, enabling the motor management system 220 to monitor and control the motor controller 222.

[0133] The recorder 230 can store some or all data communicated (such as component status, temperature, or over / undervoltage information from the components or other sensors) on the communication bus to a memory device for later reference, such as for reference by the power management system 210 or the motor management system 220 or for use in troubleshooting or debugging by a maintenance worker. The power management system 210 and the motor management system 220 can each output or include a user interface that presents status information and permits system configurations. The power management system 210 can control a charging process (for instance, a charge timing, current level, or voltage level) for the aircraft when the aircraft is coupled to an external power source to charge a power source of the aircraft, such as the first battery pack 212A or the second battery pack 212B. Features around construction and operation of the power management system 210 are described in greater detail in U.S. Patent No. 10,131,246, issued November 20, 2018, titled "COMMUNICATION SYSTEM FOR BATTERY MANAGEMENT SYSTEMS IN ELECTRIC OR HYBRID VEHICLES," which is incorporated herein by reference.

[0134] The warning panel 214 can be a panel that alerts a pilot or another individual or computer to an issue, such as a problem associated with a power source like the first battery pack 212A. The fuse and relay 216 can be associated with the first battery pack 212A and the second battery pack 212B and usable to transfer power through a converter 217 (for example, a DC-DC converter) to a cockpit battery pack 218. The fuse and relay 216 can protect one or more battery poles of the first battery pack 212A and the second battery pack 212B from a short or overcurrent. The cockpit battery pack 218 may supply power for the communication bus.

[0135] The motor management system 220 can provide control commands to the motor controller 222, which can in turn be used to operate the one or more motors 224. The motor controller 222 may further operate according to instructions from the throttle 226 that may be controlled by a pilot of the aircraft.

[0136] The power management system 210 and the motor management system 220 can execute the same or similar software instructions and may perform the same or similar functions as one another. The power management system 210, however, may be primarily responsible for power management functions while the motor management system 220 may be secondarily responsible for the power management functions. Similarly, the motor management system 220 may be primarily responsible for motor management functions while the power management system 210 may be secondarily responsible for the motor management functions. The power management system 210 and the motor management system 220 may include the same or similar computer hardware, or a single hardware may perform both functions.

[0137] Figure 3a provides a perspective view of a battery module 1 according to and embodiment of the present disclosure, which can form part of a power system usable in a vehicle, such as the aircraft of Fig. 1 A. Figure 3b provides a cross-sectional, perspective view of the battery module 1.

[0138] Referring to Figures 3a and 3b, it can be seen that the battery module 1 comprises, a housing 2; a plurality of battery cells 19 (visible in Figure 4) that are arranged in parallel within said housing 2. In this example, each battery cell 19 is held within a respective sleeve 18; the sleeves 18 are arranged in parallel within said housing 2; however, it should be understood that the respective sleeves are not essential to the present disclosure. Further, other arrangements of the sleeves 18 are possible, such as hexagonal packing or arrangement of the sleeves 18. Each battery cell 19 has a first electric pole and a second electric pole.

[0139] The battery module 1 comprises a laminated top plate 5. In this embodiment the laminated top plate 5 comprises, a substrate 6 which comprises a top substrate layer 6a and a bottom substrate layer 6b; a flex PCB 7 which is mounted on the bottom substrate layer 6b; and a conductive layer 10 which comprises at least a first conductive plate and a secondconductive plate which can be coplanar (in this example the conductive layer 10 comprises a plurality of conductive plates 10a-e as shown in Figure 4); the conductive layer 10 is mounted on the flex PCB 7. The flex PCB 7 and the conductive layer 10 are sandwiched or positioned between the top substrate layer 6a and the bottom substrate layer 6b. Preferably the top layer 6a and a bottom layer 6b can be composed of electrically insulating material; for example, the top substrate layer 6a and a bottom substrate layer 6b are each composed of plastic. The top substrate layer 6a and / or bottom layer 6b can provide protection to the conductive layer 10 and flex PCB 7 against mechanical impact and / or against heat or fire coming from battery cells 19.

[0140] A battery cell holder 8 is positioned below the laminated top plate 5. Stated differently, the laminated top plate 5 can be positioned on and / or attached to the battery cell holder 8. In this embodiment the battery cell holder 8 is mounted on a top surface 2a of a flange 2b of the housing 2. The flange 2b can have a wall having the top surface 2a extending parallel to a plane of the laminated top plate 5 and a lip 2c connected to and extending from the wall perpendicular to the plane of the laminated top plate 5 or parallel to longitudinal extents / axes of the battery cells 19. The battery cell holder 8 is designed to hold a plurality of sleeves 18 each of which contains a respective battery cell 19 (visible in figure 4). At least a portion of each of the respective sleeves 18 is located within the volume defined by the housing 2. In an embodiment in which the battery module is without sleeves 18, the battery cell holder 8 is designed to hold the plurality of battery cells 19 directly, and the battery cells 19 will be located within the volume defined by the housing 2.

[0141] The battery module 1 further comprises a fire shield element, cover, or layer 9 which is mounted above the laminated top plate 5; so, the laminated top plate 5 is located between an inner surface 9a of the fire shield element 9 and the battery cell holder 8. The fire shield element 9 defines an exhaust channel 109 through which flames and / or fumes and / or ejecta can pass. For example, the inner surface 9a can form the exhaust channel between the laminated top late 5 and the inner surface 9a. In thisembodiment the exhaust channel 109 extends perpendicular to the longitudinal axes of the battery cells / sleeves. The exhaust channel 109 can extend in parallel to longitudinal extent of the battery cell holder 8. The housing 2 comprises a flange 2b; the inner surface 9a of the fire shield element 9 can be attached or connected to the flange 2b of the housing 2. The fire shield element 9 can be attached or connected to the lip 2c of the flange 2b to extend over all of the battery cells 19, extending from the top surface 2a of the flange 2b. The fire shield element 9 can form a corner and can extend over the top surface 2a over the laminated top late 5 to form the exhaust channel 109. The fire shield element 9 is preferably composed of insulating material. The fire shield element 9 may also protect against ejecta in the event of a thermal runaway; the fire shield element 9 may also be referred to as a blast shield.

[0142] The battery module 1 further comprises a PCB 12 and a cover 13 which provides protection for the PCB 12. The PCB 12 will typically have electronic components, such as components of a battery management system including a battery control module as well components and / or connections to the power management system 210, mounted thereon. The PCB 12 is mounted on an outer surface 9b of the fire shield element 9. The battery cells 19 (which in this embodiment are accommodated in respective sleeves 18) and the PCB 12 are located on opposite sides of the fire shield element 9, accordingly the fire shield element 9 can provide protection to the PCB 12 from heat / fire / fumes that may be generated by a battery cell 19.

[0143] The cover 13 is also mounted on the on the outer surface 9b of the fire shield element 9; preferably side walls 13a, 13b of the cover 13 enclose the PCB 12 so that the PCB 12 is located within a volume defined by the cover 13 and outer surface 9b of the fire shield element 9.

[0144] Figure 4 shows perspective view of the conductive layer 10. The conductive layer 10 comprises at least two conductive plates that are preferably arranged to be coplanar. In the exemplary battery module 1 embodiment shown in the figure 4, the conductive layer 10 comprises aplurality of conductive plates 10a-10e. As shown in figure 3b, the conductive layer 10 and thus the plurality of conductive plates 10a-10e that make up the conductive layer 10, are located on one side (e.g., only one side) of the battery cells 19 (which are contained in respective sleeves 8) - specifically, the plurality of conductive plates 10a-10e are all located at a first end 19a of all the battery cells 19 in the battery module 1.

[0145] In this example the conductive layer 10 comprises a first conductive plate 10a, a second conductive plate 10b, a third conductive plate 10c, a fourth conductive plate 10d and a fifth conductive plate 10e. All of the conductive plates 10a-10e are arranged on the same plane (i.e. are coplanar); but each conductive plate 10a-e is preferably located at a different position on said plane so that the conductive plates 10a-e are mechanically independent of one another and no conductive plate 10a-e partially, or fully, overlaps, another conductive plate 10a-e (when mounted on the flex PCB 7). The conductive plates 10a-e can be separated from each other and spaced apart within the plane of the conductive layer 10. It should be understood that in this embodiment the shape of the flex PCB 7 does not exactly match the shape of the conductive layer 10, consequently only some parts or specific parts of the respective first conductive plate 10a, second conductive plate 10b, third conductive plate 10c, fourth conductive plate 10d and / or fifth conductive plate 10e, may contact or may overlay the flex PCB 7; while other parts of the respective first conductive plate 10a, second conductive plate 10b, third conductive plate 10c, fourth conductive plate 10d and / or fifth conductive plate 10e may not contact or may not overlay the flex PCB 7.

[0146] It should be understood that the conductive layer 10 may comprise any number of conductive plates greater than '1'; in an aspect of the present disclosure, all of the conductive plates of the conductive layer 10 are arranged to be at the same end 19a of the battery cells 19. Preferably, all of the conductive plates are arranged to occupy the same plane, and preferably to occupy different respective positions on said plane so that the conductive plates are mechanically independent of one another, and no conductive plate partially overlaps, or fully overlaps, anotherconductive plate (i.e. preferably, the conductive plates are separated from each other and spaced apart within the plane of the conductive layer 10). In other words, the conductive layer 10 will comprise at least a first conductive plate and a second conductive plate which are positioned on the same side of the battery cells in the battery module; preferably the at least first conductive plate and second conductive plate are arranged to occupy the same plane, and to occupy a different respective position on said plane so that the at least first and second conductive plates are mechanically independent of one another and do not partially overlap, or fully overlap, one another (i.e. preferably, the at least first conductive plate and second conductive plate are separated from each other and spaced apart within the plane of the conductive layer 10). Preferably the plurality of conductive plates of the conductive layer 10 are each shaped complementary to one another to allow the conductive plates to be arranged to occupy the same plane, and to occupy a different respective position on said plane; for example, the plurality of conductive plates could be shaped so that they can be arranged on the flex PCB 7 in an interdigital arrangement with fingers or extensions of the conductive plates coextending in the same plane without contacting each other or overlapping. Furthermore, in a preferred embodiment the at least first conductive plate is electrically connected to respective first poles of each respective battery cell 19 in the battery module, and the at least second conductive plate is electrically connected to respective second poles of each respective battery cell 19 in the battery module.

[0147] Referring back to the specific example shown in Figure 4 in which the conductive layer 10 comprises a first conductive plate 10a, a second conductive plate 10b, a third conductive plate 10c, a fourth conductive plate 10d and a fifth conductive plate 10e, all of which are located on same side of the battery cells 19 in the battery module. Cumulatively, the first, second and third conductive plates 10a-c are_electrically connected to the respective first electric poles 19a of all the battery cells 19 in the battery module (preferably by wire bonding or being wire-bonded) - in other words the first conductive plate 10a is electrically connected (for example, by wire bonding or direct physical contact) to the respective first electricpole 19a of some of the battery cells 19 in the battery module 1 that the second and third conductive plates 10b, 10c are not electrically connected to; the second conductive plate 10b is electrically connected (preferably by wire bonding) to the respective first pole of other battery cells 19 in the battery module 1 that the first or third conductive plates 10a, c are not electrically connected to; and the third conductive plate 10c is electrically connected (for example, by wire bonding or direct physical contact) to the respective first electric pole 19a of other battery cells 19 in the battery module 1 that the first or second conductive plates 10a, d are not electrically connected to. So the first, second, and third conductive plates 10a-c are arranged for conducting currents from the respective first poles 19a of all battery cells 19 in the battery module 1. The first electric pole 19a of each battery cell 19 is preferably a positive pole 19a.

[0148] Cumulatively, the fourth and fifth conductive plates 10d,10e are electrically connected to respective second electric poles 19b of all the battery cells 19 in the battery module 1 (preferably by wire bonding) - in other words the fourth conductive plate 10d is electrically connected (for example, by wire bonding or direct physical contact) to the respective second electric poles 19b (shown in Figure 5b) of some of the battery cells 19 in the battery module 1, and the fifth conductive plate 10e is electrically connected (for example, by wire bonding or direct physical contact) to the respective second electric poles 19b of each of the rest of the battery cells 19 in the battery module 1 that the fourth conductive plate 10d is not electrically connected to. So, cumulatively, the fourth and fifth conductive plates 10d,10e are arranged for conducting currents from the respective second electric poles 19b of all battery cells 19 in the battery module 1. The second electric pole 19b of each battery cell is preferably a negative pole.

[0149] In an embodiment of the battery module 1 which comprise sleeves, casing, or housing 18, and wherein each respective sleeve 18 accommodates a respective battery cell 19, each respective sleeve 18 may be electrically connected to the second electric pole 19b of the respective battery cell 19 it accommodates; the fourth and fifth conductive plates 10d,10e may be electrically connected (e.g., wire bonded) to the sleeves 18;for example, the fourth conductive plate 10d may be electrically connected (for example, by wire bonding or direct physical contact) to some of the sleeves 18 in the battery module 1, and the fifth conductive plate 10e may be electrically connected (for example, by wire bonding or direct physical contact) to the rest of sleeves 18 in the battery module 1 that the fourth conductive plate 10d is not electrically connected to. In another embodiment (e.g. an embodiment of the battery module 1 which does not comprise sleeves 18) the fourth and fifth conductive plates 10d,10e are electrically connected (e.g., wire bonded) to the battery cells 19 (for example, to an outer surface of the battery cells 19); for example, the fourth and fifth conductive plates 10d,10e are electrically connected (e.g., wire bonded) to an outer surface of the battery cells 19, wherein said outer surface of each battery cell 19 is electrically connected to the second electric pole 19b (the negative pole) of that battery cell 19, so that the fourth and fifth conductive plates 10d,10e are electrically connected to the second electric pole 19b (the negative pole) of the battery cells 19; for example, the fourth conductive plate 10d may be electrically connected (for example, by wire bonding) to respective outer surfaces of some of the battery cells 19 in the battery module 1, and the fifth conductive plate 10e may be electrically connected (preferably by wire bonding) to respective outer surfaces of the rest of battery cells 19 in the battery module 1 that the fourth conductive plate 10d is not electrically connected to. In another embodiment the fourth and fifth conductive plates 10d,10e may be wire bonded to the sleeves 18 and also wire bonded to the outer surface of the battery cells 19, wherein said outer surface of each battery cell 19 is electrically connected to the second electric pole 19b (the negative pole) of that battery cell 19.

[0150] The first conductive plate 10a, second conductive plate 10b, third conductive plate 10c, fourth conductive plate 10d, and fifth conductive plate 10e are each mounted on the flex PCB 7. Adjacent conductive plates in the conductive layer 10 are each shaped to be complementary to one another; specifically, in the battery module 1 shown in figure 4, the first conductive plate 10a and fourth conductive plate 10d have complementary shapes; the first conductive plate 10a and second conductive plate 10b havecomplementary shapes; the second conductive plate 10b and third conductive plate 10c have complementary shapes; and the third conductive plate 10c and fifth conductive plate 10d have complementary shapes. As shown in figure 4, the complementary shapes of the conductive plates 10a- 10e allow for the first conductive plate 10a, second conductive plate 10b, third conductive plate 10c, fourth conductive plate 10d, and fifth conductive plate 10e to be arranged to occupy the same plane (i.e. coplanar), but to occupy a different respective position on said plane so that the conductive plates 10a-e are mechanically independent of one another and no conductive plate partially overlaps, or fully overlaps, another conductive plate. Specifically, in the battery module 1 shown in figure 4, the conductive plates 10a-e are shaped complementary to one another so that conductive plates 10a-e that are adjacent to one another have an interdigital arrangement. For example, each of the conductive plates 10a-e can have interdigital fingers or extensions that extend, for example in parallel, in the same plane without contacting each other.

[0151] In the present embodiment of the battery module 1 the conductive layer 10 comprises a plurality of conductive plates 10a-10e that are all located at the same side of the battery cells 19 - specifically, the plurality of conductive plates 10a-10e, are all located at a first end 19a (i.e. at the end of the first electric pole 19a) of all the battery cells 19 in the battery module 1. Locating the conductive plates 10a-10e of the conductive layer 10 at the same side of the battery cells 19 advantageously eliminates the need to have long conductive wires which extend from the first end 19a of the battery cells 19 to the second opposite end 19b of the battery cells 19, thereby reducing the weight and volume of the battery module 1. However, the present disclosure is not limited to requiring all the conductive plates 10a-10e of the conductive layer 10 to be located at the same side of the battery cells 19; the present application discloses other inventive features, which do not require the conductive plates 10a-10e of the conductive layer 10 to be located at the same side of the battery cells 19._lt should be understood that features of the battery module which are described in the description may be combined in any combination; inparticular any one or more features of any one embodiment may be used in another embodiment.

[0152] Figure 5a shows perspective view of the sleeves 18 in the battery module 1; and Figure 5b shows a longitudinal section view of a sleeve 18 and battery cell 19 held in that sleeve. Preferably each of the sleeves 18 and battery cells 19 in the battery module 1 are the same as shown in Figure 5b. Each battery cell 19 preferably has a substantially cylindrical shape. The battery cells 19 can be circular or have a circular cross-section perpendicular to a longitudinal extent or axis of the battery cells 19. Correspondingly, the sleeves 18 can be circular or have a circular cross-section perpendicular to a longitudinal extent or axis of the sleeves 18.

[0153] Referring to Figure 5a it can be seen that the battery module 1 comprises a plurality of sleeves 18 each of which is configured to accommodate a respective battery cell 19, so that individual of the plurality of battery cells 19 are positioned within individual of the plurality of sleeves 18. The sleeves 18 will provide some protection to the battery cell 19 it holds, against mechanical shocks, heat, humidity, and other hazards. The sleeves 18 are an optional feature of the battery module, and may be omitted; in another embodiment, preferably in the case in which the battery cells 19 are mechanically robust enough, the sleeves 18 are omitted.

[0154] It should be understood that the battery module 1 may comprise any number of sleeves 18 and battery cells 19. The battery module 1 shown in figure 5 comprises '36' battery cells 19, and thus '36' sleeves 18 since each battery cell 19 is held within a respective sleeve 18.

[0155] The battery cells 19 are arranged in sets 119a-119d of '9'; specifically a first set 119a of '9' (arranged 3x3) battery cells 19; a second set 119b of '9' (arranged 3x3) battery cells 19; a third set 119c of '9' (arranged 3x3) battery cells 19; and a fourth set 119d of '9' (arranged 3x3) battery cells 19. In other implementations, the battery module 1 may instead include a total of 2 N or 3 N battery cells 19 where N is an integer. Themultiple battery cells 19can be arranged in one or more rows (such as two, three, four, or more rows) and one or more columns (such as two, three, four, or more columns). At least some of each of the battery cells 19 can have the same or similar structures so that the at least some of each of the battery cells 19 may be used in place of one another.

[0156] Each of the sleeves 18 may be composed of any suitable material. For example, each of the sleeves 18 may be composed of any one or more of, aluminium, and / or steel, and / or carbon fibre. In this embodiment each sleeve 18 in the battery module 1 is composed of a heat conducting material so that each respective sleeve 18 can conduct heat away from the battery cell 19 that is positioned within said respective sleeve 18. Furthermore, in this embodiment the material of each of the sleeve 18 is electrically conducting.

[0157] Figure 5b provides a longitudinal section view of a sleeve 18 and the battery cell 19 which is accommodated within the sleeve 18. Preferably, each of the sleeves 18 (and battery cells 19) in the battery module 1 has the same configuration as shown in Figure 5b.

[0158] Referring to figure 5b it can be seen that each sleeve 18 has an open end 18a (in this embodiment each sleeve 18 comprises an open top end 18a) and a closed end 18b (in this embodiment each sleeve 18 comprises a closed bottom end 18b), and a tubular portion 18c which extends between the open top end 18a and a closed bottom end 18b. Each sleeve further comprises a shoulder portion 21 which defines a rim 21 at the open top end 18a of the sleeve 18. It should be understood that it is not essential for the sleeves 18 to have a closed end 18b; in an embodiment the opposite ends 18a, 18b of the sleeve may each be open ends.

[0159] A battery cell 19 can be inserted into the sleeve 18 via the open top end 18a. The inner circumference or radius of an inner surface of the sleeve 18 can correspond (e.g., be substantially the same) as the outer circumference or radius of an outer surface of the battery cell 19 toaccommodate and position the battery cell 19 within the sleeve 18. A first end 19a (which is preferably the positive pole) of the battery cell 19 is exposed through the open top end 18a of the sleeve 18; a second end 19b (which is preferably the negative pole) of the battery cell 19 rests on the closed bottom end 18b of the sleeve 18. In this embodiment the first end 19a is the first electric pole 19a of the battery cell 19, and in this embodiment the first electric pole 19a is a positive pole 19a of the battery cell 19; the second end 19b is the second electric pole 19b of the battery cell 19, and in this embodiment the second electric pole 19b is a negative pole 19b of the battery cell 19.

[0160] The shoulder portion 21 of the sleeve can be used to secure the sleeve 18 in the battery cell holder 8; specifically, in an embodiment, the outer diameter of the tubular portion 18c will be less than the diameter of through-holes defined in the battery cell holder 8, while the outer diameter of the shoulder portion 21 will be greater than the diameter of the through-holes defined in the battery cell holder 8, thereby allowing the tubular portion 18c of the sleeve 18 to be inserted into a through-hole and allow the shoulder portion 21 to rest on an annular ledge 31 of holder plate 29a-d of the battery cell holder 8. The shoulder 21 will also strengthen the sleeve 18 to make the sleeve 18 more mechanically robust and may also increase the stiffness of the sleeve 18.

[0161] Preferably, each battery cell 19 in the battery module 1 is glued, or welded, to the respective sleeve 18 in which it is accommodated. The glue or weld will serve to hold the battery cell 19 in the sleeve 18; advantageously this will reduce the possibility of the battery cell 19 being projected from the sleeve 18 in case of an explosion or fire, thereby improving the safety of the battery module 1. It should be understood that any suitable glue or weld can be used to glue or weld the battery cell 19 to the respective sleeve 18 in which that battery cell 19 is accommodated.

[0162] In the example shown in Figure 5b the battery cell 19 is glued, using an electrically conductive glue 51, to an inner surface of the sleeve18. Specifically, in the example shown in Figure 5b, the second end 19b (which is a negative pole) of the battery cell 19 that rests on the closed bottom end 18b of the sleeve 18, is glued by electrically conductive glue 51, to the closed bottom end 18b of the sleeve 18; in this way the glue 51 not only serves to hold the battery cell 19 in the sleeve 18, but also electrically connects the negative pole 19b of the battery cell 19 to the sleeve 18. The shoulder portion 21 of each respective sleeve 18 may be electrically connected, for example wire bonded, to one of the plates 10a-10e (preferably to either the fourth conductive plate 10d, or the fifth conductive plate 10e) in the conductive layer 10, so that the negative pole 19b of the battery cell 19 is connected to said plate 10a-10e via the sleeve 18. However, for example, the negative pole 19b of the battery cell 19 will be directly electrically connected (e.g., wire bonded) to one of the plates 10a-10e (preferably to either the fourth conductive plate 10d, or the fifth conductive plate 10e) in the conductive layer 10, and the sleeve 18 is electrically connected via conductive glue, or otherwise, to the same negative pole 19b of the battery cell 19, so that it is not floating.

[0163] In an embodiment, the battery module 1 may further comprise intumescent material positioned outside each of the respective sleeves 18. Preferably intumescent material surrounds each of the respective sleeves 18. Since the sleeves 18 are an optional feature of the battery module, in another embodiment in which the battery module is without sleeves 18, the intumescent material is positioned outside each of the respective battery cells 19 in the battery module.

[0164] The thickness of the intumescent material surrounding each of the respective sleeves 18 / battery cells 19 may be in the range 0,2mm- 0.5mm; for example, thickness of the intumescent material surrounding each of the respective sleeves 18 / battery cells 19 may be 0,37mm. The thickness of the intumescent material surrounding each of the respective sleeves 18 / battery cells 19 may expand to a thickness between 2mm-6mm when heated (e.g. when heated within a predefined temperature range). For example, the thickness of the intumescent material surrounding each of the respective sleeves 18 / battery cells 19 maybe 0,37mm; during use thebattery cells 19 will generate heat; up until a predefined temperature threshold (for example, 130°C); the heat generated by the battery cells 19 will be absorbed by the intumescent material; when the intumescent material absorbs the heat the volume of the intumescent material increase, so that the thickness of the intumescent material surrounding each of sleeves 18 will swell to a thickness of 4mm.

[0165] In an embodiment the intumescent material provided in the battery module 1 will have a composition which will ensure that the intumescent material burns or reacts when it reaches a temperature which is equal to, or greater than, the predefined temperature threshold; the predefined temperature threshold may be, for example, 130°C. Such compositions are known in the art. Once the intumescent material has reacted the intumescent material will act as an insulator.

[0166] Using the intumescent material which absorbs heat up until a predefined temperature threshold and then burns or reacts at temperatures above that threshold, and acts as an insulator after burning or reacting, advantageously allows to absorb heat generated by the battery cells 19 during normal use of the battery module 1, reducing the risk of the battery cells catching fire; but also, if / when any one or more of the battery cells 19 go into thermal runaway, the heat generated by the thermal runaway will exceed the predefined temperature threshold causing the intumescent material to burn or react and act as an insulator, which prevents the heat from the thermal runaway from spreading to other battery cells 19 in the battery module 1. In this way, the intumescent material helps to contain the heat of the thermal runaway, thereby reducing the risk of a thermal runaway in one battery cell 19 causing a chain reaction of thermal runaways in the other battery cells 19 in the battery module 1.

[0167] According to a further aspect of the disclosure there is provided a battery module comprising: a housing 2 configured to contain a plurality of battery cells 19,each of the plurality of battery cells 19 having a first terminal and a second terminal; at least a first conductive plate10a-e and second conductive plate 10a-e; a first plurality of wire bonding electrically connecting a first terminal 19a of the plurality of battery cells to the first conductive plate 10a-e; and a second plurality of wire bonding electrically connecting the second terminals 19b of the plurality of battery cells to the second conductive plate 10a-e; and intumescent material positioned around each of the battery cells. Notably in this aspect of the disclosure the position of the at least first conductive plate and second conductive plate is not limited; for example the at least first conductive plate and second conductive plate may be located at opposite ends of the battery cells (i.e. the first conductive plate located at one end of the battery cells, and the second conductive plate located at the second opposite end of the battery cells), or, the at least first conductive plate and second conductive plate may be located at the same end of the battery cells. It should be understood that in an embodiment in which each of the battery cells is accommodated within a respective sleeve, the intumescent material may be positioned around each of the respective sleeves.

[0168] In an embodiment, the battery module 1 may further comprise foam material positioned outside each of the respective sleeves 18. Since the sleeves 18 are an optional feature of the battery module, in another embodiment in which the battery module is without sleeves 18, the foam material is positioned outside each of the respective battery cells 19 in the battery module.

[0169] Preferably the foam material surrounds each of the respective sleeves 18 / battery cells 19. Preferably the foam material abuts an outer surface 18e of a respective sleeve, or abuts an outer surface of a respective battery cell 19. Advantageously, because the foam material surrounds each of the respective sleeve 18 / battery cell 19, the foam material will effectivelyincrease the contact surface area between the sleeve / battery cell and the air, thereby allowing for greater heat dissipation during normal use. During normal use the battery cells 19 in the battery module 1 will generate heat; the heat generated by each respective battery cell 19 will be conducted through respective sleeves 18 (if present) and into the foam material; because the foam material is porous the foam material provides a large surface area from which heat is dissipated into the air, consequently allowing for improved heat dissipation.

[0170] The foam material may have any suitable composition. In an embodiment the foam material comprises metal.

[0171] In a preferred embodiment, intumescent material may be encapsulated in said foam material; the intumescent material may have any one or more of the features / properties of the intumescent material of the afore-mentioned embodiment. Advantageously this embodiment achieves improved heat dissipation in normal use and also allows for improved containment of the heat of a thermal runaway thereby reducing the risk of a thermal runaway in one battery cell 19 causing a chain reaction of thermal runaways in the other battery cells 19 in the battery module 1.

[0172] In an embodiment the battery module 1 may further comprise phase change material positioned outside each of the respective sleeves 18. Since the sleeves 18 are an optional feature of the battery module, in another embodiment in which the battery module is without sleeves 18, the phase change material is positioned outside each of the respective battery cells 19 in the battery module.

[0173] Preferably the phase change material surrounds each of the respective sleeves 18 / battery cells 19.

[0174] In an embodiment, the phase change material is provided in the form of a coating on each of the respective sleeves 18 / battery cells 19.

[0175] In another embodiment, the phase change material may be encapsulated in the aforementioned foam material. In one example the foam material comprises both the phase change material and intumescent material; preferably the phase change material and intumescent material are encapsulated in the foam material.

[0176] In another embodiment the phase change material is in the form of pouches which are arranged between the respective sleeves 18 / battery cells 19.

[0177] The phase change material may take any suitable form and many have any suitable composition. Any suitable, known, phase change material may be used. For example, the phase change material may be in the form of a solid which changes phase into a liquid when heated; or the phase change material may be in the form of a liquid which changes phase into a gas when heated; in the afore-mentioned examples the phase change material undergoes one phase change when heated. However, in another embodiment the phase change material may undergo two phase changes when heated; for example, the phase change material may be in the form of a solid which changes phase into a liquid when heated, and the liquid subsequently changes phase into a gas when heated.

[0178] During normal use, the battery cells 19 in the battery module 1 will generate heat; the heat generated by each respective battery cell 19 will be conducted through respective sleeves 18 (if present) and absorbed by the phase change material. The heat will be absorbed by the phase change material; upon absorbing a predefined threshold amount of heat, the phase change material will undergo one or more phase changes thereby consuming heat energy; in this way the phase change material provides cooling to the battery cells 19. In some cases any one or more of the batteries 19 may go into thermal runaway; at least some of the heat from a thermal runaway can be absorbed by the phase change material; the phase change material will undergo one or more phase changes to consume at least some of the heat from the thermal runaway, therebyreducing the risk of a thermal runaway in one battery cell 19 causing a chain reaction of thermal runaways in the other battery cells 19 in the battery module 1.

[0179] In another embodiment of the battery module 1 a layered configuration is provided comprising a layer of thermal conductive material, a layer of foam material, and a layer of intumescent material.

[0180] Specifically, in an embodiment, each battery cell 19 is held within a respective sleeve 18. A thermal conductive material is located between the battery cell 19 and an inner surface 18d of the sleeve 18. The thermal conductive material may take any suitable form. The thermal conductive material will serve to conduct heat generated by the battery cell 19, away from the battery cell 19 and into the sleeve 18 in which that battery cell 19 is accommodated.

[0181] A layer of foam material is preferably positioned outside each of the respective sleeves 18. Preferably the layer of foam material surrounds each of the respective sleeves 18. The layer of foam material preferably abuts an outer surface 18e of a respective sleeve. Advantageously, because a layer of foam material surrounds each of the respective sleeves 18, the layer of foam material will effectively increase the contact surface area between the sleeve 18 and the air, thereby allowing for greater heat dissipation during normal use.

[0182] A layer of intumescent material is preferably positioned outside the layer of foam material. Preferably the layer of intumescent material surrounds the layer of foam material. In an embodiment the intumescent material is provided as a coating on the layer of foam material; for example, for each respective sleeve 19, the foam material may be provided in a tubular form, wherein an inner surface of the tubular form abuts the sleeve and an outer surface of the tubular form being coated with a layer of intumescent material. In the afore-mentioned example the layer of intumescent material is positioned outside the layer of foam material;however, in another embodiment the layer of foam material could be positioned outside the layer of intumescent material.

[0183] The thickness of the layer of intumescent material may be in the range of 0.2mm-0.5mm; for example, thickness of the layer of intumescent material may be 0.37mm. The thickness of the layer of intumescent material may expand to a thickness between 2mm-6mm when heated (e.g. when heated within a predefined temperature range).

[0184] During normal use the battery cells 19 will generate heat; the heat generated by the battery cells 19 will be conducted to the sleeve 18 via the thermal conductive material; heat from the sleeve 18 will be conducted into the layer of foam; since the layer of foam is porous the layer of form will effectively increase the contact surface area between the sleeve 18 and the air, thereby allowing for greater heat dissipation away from the sleeve 18 into the layer of intumescent material. Up until a predefined temperature threshold (e.g. 130°C) the layer of intumescent material will absorb the heat which is dissipated from the foam layer; when the layer of intumescent material absorbs the heat dissipated from the foam layer the volume of the intumescent material increases, so that the thickness of the layer of intumescent material will swell to a greater thickness.

[0185] In the case one or more of the battery cells 19 go into thermal runaway then the heat generated by the thermal runaway will heat the layer of intumescent material to a temperature which is above the predefined temperature threshold. When the layer of intumescent material is heated above the predefined temperature threshold the layer of intumescent material will burn or react, transforming from being thermally conductive into a thermally insulative layer. In other words, below the predefined temperature threshold the layer of intumescent material is thermally conductive (conducting heat away from the form layer), whereas above the predefined temperature threshold the layer of intumescent material burns or reacts to become thermally insulative. The layer ofintumescent material will then act as an insulator which prevents the heat from the thermal runaway from spreading to other battery cells 19 in the battery module 1. In this way the intumescent material helps to contain at least some of the heat of the thermal runaway thereby reducing the risk of a thermal runaway in one battery cell 19 causing a chain reaction of thermal runaways in the other battery cells 19 in the battery module 1.

[0186] Furthermore, any flames and / or fumes and / or ejecta generated by the thermal runaway will flow through through-holes 130 which are defined in the laminated top plate 5 (as shown in Figures 8a and 8b); the flames and / or fumes and / or ejecta vent through the through holes 130 and into the exhaust channel 109 which is defined by the fire shield element 9. This exhaustion of flames and / or fumes and / or ejecta may help to prevent the spread of the fire to the other battery cells 19 in the battery module 1. Any flames and / or fumes and / or ejecta that pass through the exhaust channel 109 may be directed into the atmosphere for example.

[0187] In an embodiment the battery module 1 may further comprises, or may alternatively comprises, phase change material which, for example, is positioned outside each of the respective sleeves 18 / battery cells 19. The heat generated by each respective battery cell 19 during normal use will be absorbed by the phase change material. In the event one or more of the battery cells 19 go into thermal runaway then the heat generated by the thermal runaway will heat the phase change material; the phase change material will undergo one or more phase changes thereby consuming heat energy, thereby reducing the risk of a thermal runaway in one battery cell 19 causing a chain reaction of thermal runaways in the other battery cells 19 in the battery module 1. So in this embodiment, in the event of a thermal runaway in one or more of the battery cells 19, the phase change material will undergo one or more phase changes to absorb at least some of the heat from the thermal runaway; plus, if the battery module further comprise intumescent material, the intumescent material will burn or react to form an insulating layer which will contain at least some of heat of the thermal runaway thereby reducing the risk of a thermal runaway in onebattery cell 19 causing a chain reaction of thermal runaways in the other battery cells 19 in the battery module 1.

[0188] It should be understood that each of the sleeves 18 in the battery module 1 may have any suitable configurations. It should be understood that each of the sleeves 18 in the battery module 1 may be composed of any suitable material; for example in an embodiment each of the sleeves 18 in the battery module 1 may have a composition which comprise any one or more of, aluminium, steel, carbon fiber. Preferably each of the each of the sleeves 18 in the battery module 1 are heat conducting and / or electrically conducting; in other words, each of each of the sleeves 18 in the battery module 1 are composed of a material which is heat conducting and / or electrically conducting. Advantageously, by having the sleeve composed of heat conducting material enables the sleeve to conduct heat away from the battery cell 19 which it holds, thereby decreasing the risk of the battery cell 19 catching fire. In the case a battery cell 19 goes into thermal runaway it is desirable to contain the heat of the thermal runaway so as to prevent a chain reaction of thermal runaways being generated in the other battery cells 19 in the battery module 1; as already described, in order to address this problem in some embodiments of the battery module 1 further include intumescent material which absorbs heat from each respective sleeve, up until a predefined temperature threshold, and then burns or reacts at temperatures above that temperature threshold, and acts as an insulator after burning or reacting; the intumescent material then helps to contain the heat of the thermal runaway thereby reducing the risk of a thermal runaway in one battery cell 19 causing a chain reaction of thermal runaways in the other battery cells 19 in the battery module.

[0189] Preferably each respective sleeve 18 is composed of a material which is electrically conducting. Preferably each respective sleeve 18 is electrically connected to the negative pole 19b of the respective battery cell 1 which it holds. As already shown in Figure 5b, each battery cell 19 in the battery module 1 may be glued, or welded, to the respective sleeve 18 in which it is held. The glue or weld will serve to hold the battery cell 19 in the sleeve 18; advantageously this will reduce the possibility of the batterycell 19 being projected from the sleeve in case of an explosion or fire, thereby improving the safety of the battery module. It should be understood that any suitable glue or weld can be used to glue or weld the battery cell to the sleeve. Preferably each respective sleeve 18 is electrically connected to the negative pole 19b of the battery cell 19 that that respective sleeve 18 holds. Preferably, and as it shown in the example shown in Figure 5b, each battery cell 19 is glued, using an electrically conductive glue 51, to an inner surface of the respective sleeve 18 in which that battery cell 19 is held. Specifically, as shown in the example shown in Figure 5b, a second end 19b (which is negative pole 19b) of the battery cell 19 that rests on the closed bottom end 18b of the sleeve 18, is glued by electrically conductive glue 51, to the closed bottom end 18b of the sleeve 18; in this way the glue 51 not only serves to hold the battery cell 19 in the sleeve 18, but also electrically connects the negative pole 19b of the battery cell 19 to the sleeve 18. Preferably, the negative pole 19b of each battery cell 19 will be directly wire bonded to one of the plates 10a-10e in the conductive layer 10, and each sleeve 18 is electrically connected through the glue or otherwise to the same negative pole 19b of the battery cell 19, so that it is not floating.

[0190] Since, in this embodiment, each respective sleeve 18 is electrically connected to the negative pole 19b of the respective battery cell 1 which it holds, each respective sleeve 18 can transport current. However, most of the current are transported through an outer layer of the battery cell 19.

[0191] Each respective sleeve 18 will also provide mechanical protection and mechanical support to the respective battery cell 19 which it holds. While it is preferable that each respective sleeve 18 is composed of a material which is stronger and more robust than the respective battery cell 19 which it holds, this is not an essential feature of the disclosure. For example it can be that each respective sleeve 18 is composed of a material which is weaker and more brittle than the respective battery cell 19 which it holds, but the sleeve would still at least have the advantage of conducting heat away from the respective battery cell 19 which it holds,and would also potentially reduce the risk of the respective battery cell 19 being projected from the battery module 1 in case of a thermal runaway.

[0192] Figure 6 shows a perspective view of the battery cell holder 8. In the example shown in Figure 6 the battery cell holder 8 is configured to have a modular configuration: the battery cell holder 8 comprises, a main support platform 28 having a plurality of sockets 28a-d defined therein; and a plurality of battery cell holder plates 29a-d each of which can be inserted into and held within a respective socket 28a-d of the main support platform 28.

[0193] Each battery cell holder plate 29a-d has a plurality of through- holes 30 defined therein; the profile of each through-hole 30 can be seen in Figure 5b. As shown in Figure 5b each through hole 30 has a first portion 30a which has a diameter which substantially corresponds to, or is slightly larger, than an outer diameter of the tubular portion 18c of a sleeve 18, but is smaller than the outer diameter of the shoulder portion 21 of a sleeve 18; and a second portion 30b which has a diameter which substantially corresponds to, or is slightly larger than an outer diameter of the shoulder portion 21 of the sleeve. Thus, each through-hole 30 has a stepped profile, which defines annular ledge 31. When a sleeve 18 is positioned into a through hole 30 in a battery cell holder 8, the closed bottom end 18b and tubular portion 18c of the sleeve 18 can be inserted into and passed through both the first and second portions 30a, b of the through hole 30 until the shoulder portion 21 of the sleeve abuts ledge 31; when the shoulder portion 21 of the sleeve 18 abuts ledge 31 then the sleeve 18 is fully inserted into the through-hole 30. Preferably the second portion 30b has a depth which is larger than the thickness of the shoulder portion 21, so once the sleeve 18 has been fully inserted into the through hole 30 the shoulder portion 21 will be fully contained within the second portion 30b of the through hole 30, while the majority of the length of the tubular portion 18c of the sleeve 18 will extend from the first portion 30a of the through hole 30 into the volume defined by the housing 2.

[0194] In present embodiment since the battery module 1 comprises sleeves 18 each of which holds a respective battery cell 19, the battery cell holder 8 is configured to hold the sleeves 18, thereby indirectly holding the battery cells 19. However, since the sleeves 18 are not essential to the present disclosure, in another embodiment the battery cell holder 8 is configured to hold the respective battery cells 19 directly; for example the through-holes 30 defined in the battery cell holder plates 29a-d may each have a diameter which substantially corresponds to, or is slightly larger than, an outer diameter of the battery cells 19, so that each battery cells 19 can be received into and held directly within a respective through-hole 30 of the battery cell holder plates 29a-d.

[0195] Referring to figure 6 it can be seen that battery cells 19 are arranged in sets 119a-119d of '9'; specifically a first set 119a of '9' (arranged 3x3) battery cells 19 is held in the a first battery cell holder plate 29a; a second set 119b of '9' (arranged 3x3) battery cells 19 is held in the a second battery cell holder plate 29b; a third set 119c of '9' (arranged 3x3) battery cells 19 is held in the a third battery cell holder plate 29c; and a fourth set 119d of '9' (arranged 3x3) battery cells 19 is held in the a fourth battery cell holder plate 29d. It should be understood that the battery module 100 may have any number of battery cell holder plates, and each set of battery cells may contain any number of battery cells (preferable the number of battery cells in each set is equal).

[0196] In the example shown in figure 6 it can be seen that each battery cell holder plate 29a-d has '9' through-holes 30 defined therein, however it should be understood that each battery cell holder plate 29a-d could have any suitable number of through-holes defined therein. Similarly, in this example the main support platform 28 is shown as having '4' sockets 28a-d defined therein, however it should be understood that the main support platform 28 could have any number of sockets 28a-d defined therein. Preferably the number of battery cell holder plates 29a-d will correspond to the number of sockets 28a-d in the main support platform 28; however, it can be that the number of sockets 28a-d and battery cell holder plates 29a- d differ. It is not essential that each available socket 28a-d in the mainsupport platform 28 receive a battery cell holder plate 29a-d; it can be that battery cell holder plates are inserted into and held in only some of the available sockets 28a-d in the main support platform 28, and other remaining sockets 28a-d are left vacant.

[0197] It should be understood that it is not essential that the battery cell holder 8 have a modular configuration; in another embodiment the battery cell holder 8 comprises a single unit, such as a single plate member, having through-holes defined therein each of which can receive a respective sleeve 18 / battery cell 19.

[0198] It should be understood that while in the present embodiment the battery module 1 has a dedicated battery cell holder 8, the dedicated battery cell holder 8 is not essential to the disclosure. In another embodiment, for example, the bottom substrate layer 6b may be used to hold the sleeves 18 of the battery module 1; in said other embodiment the bottom substrate layer 6b would further have a plurality of through-holes defined therein each through-hole being configured to receive a respective sleeve 18 or battery cell 19; each through-hole in the bottom substrate layer 6b would have a diameter which substantially corresponds to, or is slightly larger, than an outer diameter of the tubular portion 18c of a sleeve 18, but is smaller than the outer diameter of the shoulder portion 21 of a sleeve 18, so that when a sleeve 18 has been fully inserted into the through hole the shoulder of that respective sleeve will rest on a surface of the bottom substrate layer 6b. Since the sleeves 18 are not essential to the present disclosure, in another embodiment the bottom substrate layer 6b is configured to hold the respective battery cells 19 directly; for example the through-holes defined in the bottom substrate layer 6b may each have a diameter which substantially corresponds to, or is slightly larger than, an outer diameter of the battery cells 19, so that each battery cells 19 can be received into and held directly within a respective through hole in the bottom substrate layer 6b.

[0199] Figure 8a shows a top view of the laminated top plate 5; and Figure 8b shows a perspective magnified view of a portion of the laminated top plate 5. As shown in Figures 8a and 8b the laminated top plate 5 comprises a plurality of through-holes 130 defined therein.

[0200] Since the laminated top plate 5 is made up of a top substrate layer 6a, bottom substrate layer 6b, a flex PCB 7, and a conductive layer 10, some through holes 130 in the laminated top plate 5 are defined by aligned respective through-holes defined in each of top substrate layer 6a and bottom substrate layer 6b, the flex PCB 7, and the conductive layer 10. Since the flex PCB 7 and also the first, second, third, fourth, and fifth conductive plates 10a-e in the conductive layer 10 may not be complete layers, some other of the through holes 130 in the laminated top plate 5 may be defined just by aligned respective through-holes 130a defined in the top substrate layer 6a and through-holes 130b defined in the bottom substrate layer 6b only - for said other through holes no part of the flex PCB 7 and no part of the first, second, third, fourth, and fifth conductive plates 10a-e is present at the location of said other through holes, consequently it is not necessary to provide holes in the flex PCB 7 and conductive layer 10 in order to achieve said other through holes 130 that extend through the laminated top plate 5.

[0201] As shown in Figure 8a in the battery module 1 a respective through-hole 130 is provided above each respective battery cell 19 in the battery module 1. The first end 19a (which is the first electric pole 19a of the battery cell 19; the first electric pole 19a is the positive pole of the battery cell 19) of each battery cell 19 is exposed through the through hole 130.

[0202] Additionally, the top substrate layer 6a comprises a plurality of secondary through-holes 140 defined therein. A portion of either the first, second, third, fourth, or fifth conductive plates 10a-e of the conductive layer 10, is exposed through a respective secondary through-hole 140 defined in the substrate layer 6a.

[0203] Electrically conductive wires, rods, or connections 81 are connected to respective battery cells 19; each of the electrically conductive wires 81 is arranged to pass through a respective through hole 130 in the laminated top plate 5. In other words each electrically conductive wire 81 extends from one side of the laminated top plate 5 where it is electrically connected to a respective battery cell 19 (for example, by wire bonding), to the other side of the laminated top plate 5, though a respective through hole 130 in the laminated top plate 5. Each electrically conductive wire 81 can be either connected to the positive pole 19a or negative pole 19b of a battery cell 19.

[0204] Each electrically conductive wire 81 is further arranged to extend through a respective secondary through-hole 140 in the top substrate layer 6a where they are electrically connected (for example, by wire bonding) to the conductive layer 10 (specifically electrically connected to either the first, second, third, fourth, or fifth conductive plates 10a-e). In this embodiment those electrically conductive wires 81 that are electrically connected to the first electric pole 19a of a battery cell are electrically connected (preferably by wire bonding) to either the first, second or third conductive plates 10a-c; while those electrically conductive wires 81 that are electrically connected to the second electric pole 19b of a battery cell are electrically connected (preferably by wire bonding) to either the fourth or fifth conductive plates 10d,10e.

[0205] Not only do the through holes 130 in the laminated top plate 5 allow for electrical connection of the battery cells 19 to either the first, second, third, fourth, or fifth conductive plates 10a-e in the conductive layer 10, but the through holes 130 also provide openings through which flames and / or fumes and / or ejecta can pass from one side of the laminated top plate 5 to the exhaust channel 109 which is defined by the fire shield element 9; if, for example a battery cell 19 explodes or catches fire, flames and / or fumes and / or ejecta from that explosion / fire can vent through the through holes 130 and into the exhaust channel 109 which is defined by the fire shield element 9 (this may help to prevent the spread of the fire to the other battery cells 19 in the battery module 1).

[0206] Figure 7 shows a perspective view of the flex PCB 7. In the present embodiment the conductive layer 10 is mounted on the flex PCB 7; in an embodiment only a portion of the first conductive plate 10a contacts the flex PCB 7, and / or only a portion of the second conductive plate 10b contacts the flex PCB 7, and / or only a potion of the third conductive plate 10c contacts the flex PCB 7, and / or only a portion of the fourth conductive plate 10d contacts the flex PCB 7, and / or only a portion of the fifth conductive plate 10e contacts the flex PCB 7. Some portions of the flex PCB 7 are not overlayed by any part of the first, second, third, fourth, or fifth conductive plates 10a-e; in other words portions of the flex PCB 7 do not cover the same surface as the first, second, third, fourth, or fifth conductive plates 10a-e.

[0207] The flex PCB 7 may comprise a thin insulating polymer film 73 having conductive tracks (not visible in figure 7) affixed thereto and possibly a plurality of electronic components connected with those tracks. A thin polymer coating (not shown) may be provided to protect the tracks.

[0208] The electronic components may include one or more sensors, one or more switches (such as relays, MOSFETs, IGBTs) and / or one or more controllers. Each track of the conductive layer may, in certain implementations, be constructed to withstand the current from no more than one battery cell, or a portion of the current from one battery cell, so that each track can be made relatively thin and light.

[0209] Referring to Figures 7 and 8b, it can be seen that the flex PCB 7 further comprises connecting portions, rods, or extensions 71, which extend into the through holes 130b defined in the bottom substrate layer 6b. A sensor 172, preferably a temperature sensor, is mounted onto each connecting portion 71, preferably on the lower side of that connecting portion 71, and is connected to other tracks and / or components on the flex PCB 7 through conductive tracks along each such portion. The sensor can measure the temperature of the corresponding battery cell 19.

[0210] The temperature sensor 172 and / or the connecting portion 71 is preferably directly glued onto the first end 19a of the battery cell 19; the first end 19a of the battery cell 19a is exposed through the open top end 18a of the sleeve 18. Preferably the temperature sensor 172 and / or the connecting portion 71 is glued with a thermal glue.

[0211] One or more other sensors can be provided on the Flex PCB 7; for example, any one or more of, an infrared sensor (e.g. an infrared sensor which may be configured to measure the heat of one or more of the battery cells 19), a pressure sensor (e.g. a sensor for measuring an internal pressure of each or the plurality of battery cells 19), a thermocouple sensor, a hydrogen sensor, a light sensor, a voltage sensor, a current sensor, and / or may be mounted on the flex PCB 7. Any one of more of the other sensors may be mounted on a PCB track of flex PCB 7. In a preferred embodiment an infrared sensor and / or a hydrogen sensor and / or a pressure sensor and / or a light sensor, is located above the laminated top plate (e.g. an infrared sensor and / or a hydrogen sensor and / or a pressure sensor and / or a light sensor, may be mounted on the PCB 12 which is located between the laminated top plate 5 and the fire shield 9); in this location the infrared sensor can, for example, sense heat generated with a battery cell 19 catches fire.

[0212] One or more switches can be provided onto the flex PCB 7 and used for selectively disconnecting each single battery cell, for example in case of over-temperature, over-current, over-voltage, over-pressure and / or other malfunctions of the battery cell 19.

[0213] The flex PCB 7 is electrically connected to the power management system 210, via electrical connectors 72a-72d; specifically the electrical connectors 72a-72d connect the flex PCB 7 to the PCB 12 and the PCB 12 is in turn electrically connected to the power management system 210 which is configured to manage the battery cells 19 (specifically manages the distribution of the power from the battery cells to the power the electric vehicle).

[0214] In another embodiment the battery module 1 further comprises an infrared sensor which is configured to measure the heat of the one or more of the battery cells 19 through the cover 13 of the battery module. Accordingly, in this embodiment the infrared sensor is preferably mounted on an outside surface of the cover 13 of the battery module 1 or is positioned above the outside surface of the cover 3.

[0215] Figure 9a provides a perspective view of a battery module 100 according to an embodiment of the present disclosure; figure 9b is a cross- sectional, perspective view of the battery module 100 shown in figure 9a. The battery module 100 has many of the same features as the battery module 1 shown in Figures 3a-8b and like features are awarded the same reference numbers. The battery module 100 further comprises a cooling means 111 which is operable to cool the battery cells 19 in the battery module 100. In an embodiment the cooling means 111 may be located inside the housing 2; in another embodiment the cooling means 111 is located outside of the housing 2.

[0216] In the preferred embodiment, as shown in figures 9a and 9b, the cooling means 111 is provided outside the housing 2. Specifically, as shown in figures 9a and 9b, the cooling means 111 is mounted on an outer surface of a side wall 2a of the housing 2. The side wall 2a of the housing 2 has a plurality of holes 132 defined therein.

[0217] In should be understood that the cooling means 111 may take any suitable form; preferably the cooling means 111 is operable to generate a flow of air. In the example shown in figures 9a and 9b the cooling means comprises a plurality of fans 102. Preferably the number of fans 102 correspond to the number of sets 119a-119d of '9' battery cells; in this embodiment there the battery module 100 comprises '4' sets 119a-119d of '9' battery cells, so the battery module comprises '4' fans 102, one fan 102 for cooling each set 119a-119d of battery cells.

[0218] Each of the fans 102 is mounted on the outer surface of a side wall 2a of the housing 2. Each of the fans 102 can be selectively operated to generate a flow of air which can cool the battery cells 19 belonging to a respective set 119a-119d; in an embodiment each of the fans 102 can be selectively operated to generate a flow of air which can cool the sleeves 18 which hold the respective battery cells, and thus cool the battery cells 19 held within those respective sleeves 18.

[0219] Each fan 102 is arranged so that the flow of air generated by that fan in operation will pass through the one or more of the holes 132 in the side wall 2a of the housing 2, so that the air flow can pass into the housing 2 to cool the battery cells 19. It should be understood that the side wall 2a of the housing may have any number of holes 132 defined therein; in this embodiment the side wall 2a of the housing 2 comprises '4' holes 132 defined therein; each respective fan 102 is arranged so that the flow of air generated by each fan in operation will pass through a respective hole 132.

[0220] In an embodiment the holes 132 are located adjacent to the second opposite end 19b of the battery cells 19; preferably the holes 132 are located below the battery cells 19. Consequently, the flow of air generated by the fans 102 during in operation will pass through the respective holes 132 in the side wall 2a of the housing 2 and will flow from below the battery cells 19, towards the laminated top plate 5. As the air flow passes over the battery cells 19 (or over the respective sleeves 18 within which the battery cells 19 are held), the air flow will cool the battery cells 19. The air flow will pass through the through the through holes 130 in the laminated top plate 5 and into the exhaust channel 109 which is defined by the fire shield element 9.

[0221] Importantly, the fire shield element 9 is impermeable to the air flow. Furthermore, as can be seen in figure 9b the PCB 12 located at one side of the fire shield (specifically the PCB 12 is mounted on the outer surface 9b of the fire shield element 9), and the plurality of battery cells 19 and holes 132 through which the air flow from the fans 102 pass, arelocated on the other, opposite, side of the fire shield 9, so that the fire shield is located between the PCB 12 and the plurality of battery cells 19. Consequently, the fire shield element 9 will block the air flow generated by the fans 102 from passing to the PCB 12; this will ensure that electronic components on the PCB 12 are protected against dirt or residue that may be in said air flow. The air flow will pass into the exhaust channel 109 where it is directed into the atmosphere.

[0222] Thus, according to a further aspect of the present disclosure there is provided a battery module 100 comprising: a housing 2 configured to contain a plurality of battery cells 19, each of the plurality of battery cells having a first terminal and a second terminal; at least a first conductive plate and second conductive plate; a first plurality of wire bonding electrically connecting a first terminal of the plurality of battery cells to the first conductive plate; and a second plurality of wire bonding electrically connecting the second terminals of the plurality of battery cells to the second conductive plate; a fire shield element 9 which is configured to define an exhaust channel 109; a PCB 12 located at a first side of the fire shield, and wherein the plurality of battery cells are located at a second opposite side of the fire shield, so that the fire shield is located between the PCB and the plurality of battery cells; and a cooling means 111 which is arranged to provide a cooling fluid (such as an air flow for example) which can cool the plurality of battery cells 19, and wherein said cooling means 111 is also located at said second opposite side of the fire shield element 9, and wherein the fire shield element 9 is configured to be impermeable to the cooling fluid provided by the cooling means. Notably in this aspect of the disclosure the position of the at least first conductive plate and second conductive plate is not limited; for example the at least first conductive plate and second conductive plate may be located at opposite ends of the battery cells (i.e. the first conductive plate located at one end of the battery cells, and thesecond conductive plate located at the second opposite end of the battery cells), or, the at least first conductive plate and second conductive plate may be located at the same end of the battery cells. Also, notably in this aspect of the disclosure the battery module may or may not further comprise intumescent material.

[0223] In the afore-mentionedembodiment the air flow comes from fans which are mounted on the side wall of the housing; it can be advantageous to locate the fans on the side wall of the housing to minimize the vertical footprint of the battery module. However, in another embodiment, the cooling means 111 (such as fans) may be located below the battery cells; for example in another embodiment the laminated top plate 5 is located at one end 19a of the battery cells 19 and the cooling means 111 is located at a second opposite end 19b of the battery cells 19; for example the laminated top plate 5 is located above the battery cells 19 and the cooling means 111, in the form of fans 102, is located beneath the battery cells 19 so that cooling is provided from below the battery cells 19. Preferably the fans 102 are located beneath the battery cells 19 and inside the housing 2. Preferably a respective fan 102 is aligned beneath a respective set 119a- 119d of '9' battery cells, or, a respective fan 102 is aligned beneath a respective battery cell 19. Each of the fans 102 can be selectively operated to generate a flow of air which can cool a respective set 119a-119d of '9' battery cells, or cool a respective battery cell 19; in an embodiment each of the fans 102 can be selectively operated to generate a flow of air which can cool sleeves 18 above that fan 102, and thus cool the battery cell 19 held within that respective sleeve 18.

[0224] Preferably, the battery module 100 further comprises a plurality of temperature sensors 172 (the same as the temperature sensors 172 shown in Figure 7). Each temperature sensor 172 is arranged to measure the temperature of a respective battery cell 19.

[0225] In the exemplary battery module 100 shown in figures 9a and 9b, the battery cells 19 (and / or respective sleeves 18 which hold the respectivebattery cells 19), the temperature sensors 172, and the fans 102, are modular; this means that any one or more of the battery cells 19 (and / or any one or more of the sleeves 18 which hold respective battery cells 19), temperature sensors 172, and / or fans 102, can be selectively removed from the battery module 100. Likewise, if the battery module 100 is not at full capacity, then one or more of the battery cells 19 (and / or one or more of the sleeves 18 which hold respective battery cells 19), temperature sensors 172, and / or fans 102, may be selectively added to the battery module 100.

[0226] The battery module 100 shown in figures 9a and 9b further comprises a controller 110 which is operably connected to each of the temperature sensors 172 and to each of the fans 102. The controller 110 further comprises a memory which stores an ID of each temperature sensor 172 and associated with each respective temperature sensor ID is an ID of a respective fan 102 (and / or an ID of each respective set 119a-119d); these IDs will enable the controller to 110 to know which fan 102 to operate if a temperature sensor 172 indicates that the temperature of a battery cell 19 in a particular set 119a-119d, is above a predefined threshold temperature.

[0227] The controller 110 can receive temperature measurements taken by each of the temperature sensors 172; the controller 110 will compare the received temperature measure to a predefined threshold temperature, and if the temperature measurement is above a predefined threshold temperature then the controller 110 can operate the fan 102 which is located adjacent the set 119a-119d which that battery cell 19 is a member of, so that the fan 102 generates an air flow which passes through the respective hole 132 in the side wall 2a of housing, and over the set 119a- 119d which that battery cell 19 is a member of, so that the battery cell 19 (or the sleeve 19 and the battery cell within the sleeve 18) is cooled to a temperature which is within a predefined temperature range. For example, when the controller 110 receives a temperature measurement from a temperature sensor 172 which indicates that the temperature of a battery cell 19 is above a predefined threshold temperature, then the controller 110 may first identify the ID of the temperature sensor 172 from which the temperature measurement was received; then the controller 110 mayretrieve from the memory the ID of the respective fan 102 which is associated in the memory with the ID of the temperature sensor 172; the controller will then operate the fan 102 with said retrieved ID to generate an air flow which cools the battery cell 19 (or sleeve 18 and the battery cell 19 within the sleeve 18) to a temperature which is within a predefined temperature range.

[0228] Preferably the controller 110 is configured to maintain the all of the battery cells 19 in the battery module 100 at a temperature between 30°C-40°C. For example, the predefined threshold temperature may be 40°C and the predefined temperature range may be 30°C-40°C. The controller 110 may be configured to receive temperature measurements from each of the temperature sensors 172; when the controller receives a temperature measurement from a temperature sensor 172 which is above the threshold temperature 40°C, then the controller will operate the fan 102 which is located adjacent the set 119a-119d which that battery cell 19 is a member of, so that the fan 102 generates an air flow which passes through the respective hole 132 in the side wall 2a of housing, and over the set 119a- 119d which that battery cell 19 is a member of, so that the battery cell 19 (or the sleeve 18 and the battery cell 19 within the sleeve 18) is cooled to a temperature which is within the range 30°C-40°C. Once all the battery cells in the set 119a-119d are within the range 30°C-40°C, the controller 110 can then turn off the fan 102.

[0229] Advantageously, maintaining a battery cell 19 within the predefined temperature range will ensure that the battery cell 19 does not over-heat; this will ultimately extend the lifetime of that battery cell 19. Furthermore, maintaining all of the battery cells 19 in the battery module 100 within a predefined temperature range will ensure a more uniform life of the battery cells 19 within the battery module 100. Furthermore, having individual fans 102 to cool a respective set 119a-119d of battery cells 19 (or to cool each individual batter cell 19) in the battery module 100, allows for more energy efficient cooling: Because of their location in the battery module 100 (for example if a battery cell 19 is located close to the surface of a wing) some battery cells 19 in the battery module 100 will rarely heatto temperatures above the predefined threshold temperature; according these battery cells 19 may rarely receive cooling. Likewise, because of their location in the battery module 110 (for example if a battery cell 19 is located close to an engine) some battery cells 19 in the battery module 100 will frequently heat to temperatures above the predefined threshold temperature; accordingly, these battery cells 19 may frequently receive cooling. In other words, during operation, only some of the battery cells 19 in the battery module 100 may heat to a temperature that exceeds the predefined temperature threshold, while other battery cells 19 in the battery module 100 may be at a temperature which is below the predefined temperature threshold. Cooling the battery cells 19 that exceeds the predefined temperature threshold ensures that all of the cells in the battery module 100 age uniformly. Advantageously, the battery module 100 of the present disclosure has individual fans 102 to cool a respective set 119a-119d of battery cells 19 (or to cool each individual batter cell 19) in the battery module 100, which allows to selectively cool only those sets 119a-119d (or individual battery cells 19) which have a battery cell 19 with a temperature that exceeds the predefined temperature threshold. Also, those battery cells 19 in the battery module 100 that more frequently heat to a temperature exceeding the predefined temperature threshold can more frequently be cooled selectively, than those battery cells that less frequently heat to a temperature exceeding the predefined temperature.

[0230] According to a further aspect of the present disclosure there is provided a battery module which comprises, a plurality of battery cells; and a cooling system which comprises at least one inlet and at least one outlet, and a cooling duct along which a cooling fluid can flow, wherein the cooling duct is fluidly connected between the at least one inlet and at least one outlet. Cooling fluid flowing in the cooling duct can absorb heat which has been generated by the battery cells. It should be understood that the aforementioned battery assembly may have any one or more of the features of any of the other battery assembly embodiments described in the present disclosure. It should be understood that any of thebattery assembly embodiments in the present disclosure may have a battery module with the aforementioned features, or variations therefore as will be described in the following.

[0231] In an embodiment the battery module comprises at least one thermally conductive member which is arranged to be in thermal communication with a least one of the battery cells; and wherein the cooling duct is arranged to be in thermal communication with the thermally conductive member so that cooling fluid flowing in the cooling duct can absorb heat from the thermally conductive member.

[0232] The battery cells in the battery module may take any suitable form. In an embodiment each of the plurality of battery cells is a cylindrical battery cell. Each of the battery cells may be held within a respective sleeve (like the sleeve 18 in the assembly 1). The sleeve may comprise electrically insulative material. In an embodiment each sleeve may serve to electrically and physically isolate the battery cell it holds from the other battery cells in the battery module. In another embodiment each of the plurality of battery cells is a pouch battery cell; each pouch battery cell may comprise a pouch, and a positive node and negative node which protrude from said pouch. In another embodiment each of the plurality of battery cells is a prismatic battery cell.

[0233] The cooling fluid may take any suitable form. For example, in an embodiment the cooling fluid may be a liquid, such as water, and / or water- glycol and / or any suitable liquid mix of materials which can absorb heat energy. In another embodiment the cooling fluid may be a gas, such as air (i.e. an air flow).

[0234] In an embodiment the cooling system may further comprise a heat exchanger which is fluidly connected to the at least one outlet. In an embodiment the at least one outlet of the cooling system is fluidly connected to an input of the heat exchanger so that cooling fluid that has flowed through the cooling duct and out of the outlet can flow into theheat exchanger. Heat energy in the cooling fluid (i.e. heat energy that was absorbed by the cooling fluid as it flowed through the cooling duct) can be absorbed by the heat exchanger thereby recooling the cooling fluid. An output of the heat exchanger may be fluidly connected to the at least one inlet of the cooling system, so that cooling fluid that has been recooled by the heat exchanger maybe flowed into the at least one inlet of the cooling system and flowed again along the cooling duct where it can be used again to absorb heat energy.

[0235] In an embodiment the cooling fluid is air and natural convection may be used to flow air through the cooling duct. For example, if the battery module is used in a vehicle, such as an electric aircraft, then the at least one inlet of the cooling system may be arranged so that movement of the aircraft moves (e.g. as the aircraft flies) causes air to flow into the at least one inlet, along the cooling duct, and out the at least one outlet.

[0236] In another embodiment the cooling system of the battery module may further comprise an air-flow generating means, such as one or more fans for example, which can be selectively operated to generate an air flow which passes into the at least one inlet, along the cooling duct, and out the at least one outlet. The battery module may comprise a controller (such as the controller 110 of the assembly 1) which may be operably connected to the air-flow generating means, and which may be configured to selectively initiate the air-flow generating means to generate said airflow in response to one or more of the battery cells reaching a temperature which is equal to, or greater than, a predefined threshold temperature.

[0237] In another embodiment an external air-flow generating means, such as one or more fans which are external to the battery module (i.e. airflow generating means which is not part of the battery module), may be selectively operated (preferably by a controller of the battery assembly) to generate an air flow which can flow into the at least one inlet, along the cooling duct, and out the at least one outlet of the cooling system of the battery module.

[0238] In an embodiment the cooling fluid is a liquid (i.e. a cooling liquid). For example, in an embodiment the cooling fluid may be a liquid, such as water, and / or water-glycol and / or any suitable liquid mix of materials which can absorb heat energy. In an embodiment the cooling system of the battery module may further comprise at least one pump which is configured to selectively pump cooling liquid into the at least one inlet, along the cooling duct, and out the at least one outlet. The battery module may comprise a controller (such as the controller 110 of the assembly 1) which is operably connected to the at least one pump, and which is configured to selectively initiate the at least one pump to pump cooling fluid into the at least one inlet, along the cooling duct, and out the at least one outlet, in response to one or more of the battery cells reaching a temperature which is equal to, or greater than, a predefined threshold temperature.

[0239] In another embodiment at least one external pump, (i.e. at least one pump which is not part of the battery module), may be selectively operated (preferably by a controller of the battery assembly) to pump cooling liquid into the at least one inlet, along the cooling duct, and out the at least one outlet of the cooling system of the battery module.

[0240] In an embodiment the cooling system may further comprise a heat exchanger which is fluidly connected to the at least one outlet. In an embodiment the at least one outlet of the cooling system is fluidly connected to an input of the heat exchanger so that the cooling liquid that has flowed through the cooling duct and out of the outlet can flow into the heat exchanger. Heat energy in the cooling liquid (i.e. heat energy that was absorbed by the cooling liquid as it flowed through the cooling duct) can be absorbed by the heat exchanger thereby recooling the cooling liquid. An output of the heat exchanger may be fluidly connected to the at least one inlet of the cooling system, so that cooling liquid that has been recooled by the heat exchanger maybe flowed into the at least one inlet of the cooling system and flowed again along the cooling duct where it can be used again to absorb heat energy

[0241] The thermally conductive member may take any suitable form. For example, the thermally conductive member may be in the form of a plate. The thermally conductive member may comprise any suitable thermally conductive material; for example, the thermally conductive member may comprise material such as aluminium and / or an aluminium alloy, and / or a magnesium alloy, or a mixture of such materials e.g. an alloy comprising both aluminium and magnesium.

[0242] Preferably the battery module further comprises a housing (like the housing 2 of the assembly 1) within which the plurality of battery cells are located. In an embodiment the thermally conductive member is integral to the battery module; for example, the thermally conductive member may integral to the housing of the battery module. In another embodiment the thermally conductive member is not integral to the housing, but is arranged within the battery module so that it is in thermal communication at least one of the battery cells; for example the thermally conductive member may be arranged to be in thermal communication with the housing, and heat from the battery cells is conducted through the housing to the thermally conductive member.

[0243] In an embodiment the thermally conductive member may comprise a main portion and one or more subsidiary portions which extend from the main portion. The thermally conductive member may be arranged in the battery module so that the subsidiary portions project into the cooling duct. For example, in an embodiment the thermally conductive member comprises a planar main portion which comprises thermally conductive material, and a plurality of subsidiary portions in the form of a plurality of projections, each of which comprise thermally conductive material, and each of which extend from the planar main portion. In an embodiment the thermally conductive member is arranged so that the plurality of projections extend into the cooling duct. The projections increase the surface area of the thermally conductive member enabling the thermally conductive member to absorb more heat energy; for example projections will increase the contact area between the thermally conductive member and the cooling fluid flowing in the cooling duct, therebyenabling more heat transfer from the thermally conductive member to the cooling fluid. It should be understood that the thermally conductive member is not limited to requiring projections; the thermally conductive member may comprise any suitable feature or any surface texture that increases the surface area of the thermally conductive member that the cooling fluid flowing in the cooling duct can contact.

[0244] In an embodiment the cooling duct is integral to the thermally conductive member. In an embodiment the cooling duct is defined by the thermally conductive member. In an embodiment the cooling duct is defined by a channel, or groove, defined in the thermally conductive member. In an embodiment the thermally conductive member is shaped so that is defines a volume which defines the cooling duct. In another embodiment the cooling duct is not integral to the thermally conductive member; for example, the cooling duct may be formed by a part independent (e.g. mechanically independent) of the thermally conductive member.

[0245] In an embodiment the at least one inlet and at least one outlet are integral to the thermally conductive member. In an embodiment the at least one inlet and at least one outlet are defined by the thermally conductive member. In an embodiment the at least one inlet and at least one outlet are defined by a channel, or groove, defined in the thermally conductive member. In an embodiment the thermally conductive member is shaped so that it defines at least one opening which defines the at least one inlet and is shaped so that it defines at least one opening which defines the at least one outlet. In another embodiment the at least one inlet and at least one outlet are not integral to the thermally conductive member; for example, the at least one inlet and at least one outlet may be formed by a part independent (e.g. mechanically independent) of the thermally conductive member.

[0246] In an embodiment the at least one inlet is located at, or approximately which is at a centre of the one or more battery cells whichare known to heat to the highest temperature during use. For example the at least one inlet may be aligned directly below (or above) a point which is approximately at a centre of one or more of the battery cells which are known to heat to the highest temperature during use. In an embodiment the at least one inlet is located at, or approximately at, a position which is aligned below (or above) a point which is at a centre of the plurality of battery cells. Typically during use the battery cells which are located at the centre of the plurality of battery cells will heat to the highest temperature (and thus have the highest risk of catching fire) during use; having the inlet located at, or approximately at, a position which is below (or above) a centre of the plurality of battery cells, allows the cooling fluid to first absorb heat energy from these battery cells that have the highest temperature.

[0247] In an embodiment the battery module further comprises heat absorbing member which is arranged to be in thermal communication the at least one of the battery cells; and wherein the thermally conductive member is further arranged to be in thermal communication with the heat absorbing member. It should be understood that the heat absorbing member is any optional feature. The heat absorbing member may take any suitable form. In an embodiment the heat absorbing member is arranged between adjacent battery cells. In an embodiment the thermally conductive member is arranged to be in thermal communication with heat absorbing member. In an embodiment the thermally conductive member is arranged to be in thermal communication with heat absorbing member and with at least one of the battery cells (preferably all of the battery cells).

[0248] In an embodiment the heat absorbing member comprises an encapsulation element which holds a heat absorbing material. For example, in an embodiment the heat absorbing member may comprise an encapsulation element which comprises a plurality of pouches each of which hold heat absorbing material; in another embodiment the heat absorbing member comprises an encapsulation element which defines a single pouch which holds heat absorbing material; in another embodiment the heat absorbing member comprises an encapsulation element whichcomprises matrix and the heat absorbing material is contained within / impregnated in the matrix; in another embodiment the heat absorbing member comprises an encapsulation element which comprises a casing and a matrix which is contained within the casing, and wherein the heat absorbing material is contained within / impregnated in the matrix and is also contained within a volume defined by the casing. In another embodiment the encapsulation element may comprise a porous material and the heat absorbing material may be held in the pores of the encapsulating element; the porous material may be held within a casing. In another embodiment the heat absorbing member comprises an encapsulation element which comprises a matrix and the heat absorbing material is contained within / impregnated in the matrix, and further comprises a plurality of pouches each of which hold heat absorbing material; in another embodiment the heat absorbing member comprises an encapsulation element which comprises a matrix and the heat absorbing material is contained within / impregnated in the matrix and wherein the encapsulation element further defines a single pouch which holds heat absorbing material. The encapsulation element may comprise flexible, and / or compressible, material; this will allow easy preforming of the encapsulation element and / or makes the encapsulation element conformable.

[0249] In an embodiment the plurality of pouches, or single pouch, of the encapsulation element is air-tight (in other words the heat absorbing material is held, air-tight, in encapsulation element). In an embodiment the encapsulation element comprises material which is self-extinguishing. In an embodiment the encapsulation element comprises a metallic sheet (e.g. a thin metallic sheet) which is configured and arranged for form a radiation barrier. In an embodiment the encapsulation element comprises electrically insulating material. In an embodiment the encapsulation element comprises thermally conductive material. In an embodiment the encapsulation element comprises material which is both electrically insulating and thermally conductive. The encapsulation element may comprise any one or more of, aluminum-polymer laminates, and / or nonflammable and / or watertight cloth such as fiber-reinforced polymers. In anembodiment in which the encapsulation element comprises a plurality of pouches, or is configured to define a single pouch, then encapsulation element may comprise any one or more of, aluminum-polymer laminates, and / or non-flammable and / or watertight cloth such as fiber-reinforced polymers. The encapsulation element may comprise any one or more of, graphite (e.g. expanded graphite) and / or aerogel and / or non-woven carbon fiber and / or glass fiber. In an embodiment in which the encapsulation element comprises a matrix and the heat absorbing material is contained within / impregnated in the matrix, then the matrix of the encapsulation element may comprise any one or more of, graphite (e.g. expanded graphite) and / or aerogel and / or non-woven carbon fiber and / or glass fiber.

[0250] In an embodiment the heat absorbing member may further comprise a thermally conductive material which is arranged to enhance the transfer of heat energy from the one of the battery cells to the heat absorbing material that is held in the encapsulation element. Said thermally conductive material may take any suitable form: for example, in an embodiment wherein the encapsulation element comprises a matrix and the heat absorbing material is contained within / impregnated in the matrix, then the matrix may comprise thermally conductive material; in this case the matrix may promote the conduction of heat energy to the heat absorbing material which is contained within / impregnated in the matrix. In another example the thermally conductive material may comprise a porous material and the heat absorbing material may be held in the pores of the thermally conductive material. In yet another embodiment the thermally conductive material is the form of an additive, or filler, to the heat absorbing material which is held in the encapsulation element. In an embodiment the thermally conductive material of the heat absorbing member may comprise flexible, and / or compressible, material (this may facilitate compatibility between the thermally conductive material and the encapsulation element).

[0251] In an embodiment the heat absorbing material held in the encapsulation element is a material which can undergo a phase change when heated e.g. the heat absorbing material may be a material which canundergo a phase change when heated to a predefined temperature. In an embodiment the heat absorbing material is a solid in its initial state, and changes phase to a liquid (fusion) and / or gas when heated to a predefined temperature; in another embodiment the heat absorbing material is a fluid (such as a liquid or gel) in its initial state, and changes phase to a gas (vaporization) when heated to a predefined temperature; heat energy is absorbed through latent heat capacity. In another embodiment the heat absorbing material held in the encapsulation element is a material which can undergo a chemical phase transition when heated e.g. the heat absorbing material may be a material which can undergo a chemical phase transition when heated to a predefined temperature; the chemical phase transition may be a chemical phase transition involving structural water release (in the form of vapor), and / or a glass transition, and / or any other chemical transformations such as decomposition (wherein heat is absorbed through reaction enthalpy). In an embodiment the heat absorbing material is configured to absorb significant heat in nominal use of the battery module, so as to homogenize the temperature of the battery cells in the battery module (and thereby ensuring that the battery cells in the battery module age more uniformly), with discrete or latent heat absorption. In an embodiment the heat absorbing material is configured to absorb the majority of the heat generated by the battery cells in the battery module, between the maximum nominal operation temperature and the thermal runaway temperature (so as to effectively mitigate thermal runaway propagation). In an embodiment the heat absorbing material may be configured (e.g. dimensioned) to absorb enough excess heat generated by each of the battery cells during use, that would otherwise trigger the thermal runaway of other battery cells

[0252] It should be understood that heat absorbing material held in the encapsulation element may have any suitable composition. The heat absorbing material can absorb part or the totality of the heat of the battery cells by the gradual increase of temperature of the heat absorbing material, defined as discrete heat, and may be characterized by the heat capacity of the heat absorbing material. In an embodiment heat absorbing material comprises non-flammable or self-extinguishing material. In anembodiment the heat absorbing material held in the encapsulation element is in the form of a fluid which can absorb heat energy and which can undergo a phase change when heated above a predefined temperature.

[0253] In an embodiment the heat absorbing material held in the encapsulation element comprises water (or any other cooling fluid) plus a gelling agent (or thickening agent) fluid mixture which can absorb heat energy and which can undergo a phase change when heated above a predefined temperature. Advantageously, in this embodiment in which the heat absorbing material comprises a gelling agent (or thickening agent), if for example a pouch (containing the heat absorbing material) of the encapsulation element is pierced the gelling agent (or thickening agent) will ensure that the fluid mixture does not flow out through the hole in the pouch. It should be understood that any suitable gelling agent (or thickening agent) may be used. The gelling agent and / or a thickening agent may take any suitable form; the gelling agent and / or a thickening agent is any agent that can increase viscosity of a liquid. A rheology modifier is just one example of a possible gelling agent and / or a thickening agent. Typically, only in the low fraction of gelling agent (or thickening agent) is used in the fluid mixture in order decrease the risk of leakage our of a pierced pouch, which does not compromise significantly the heat absorption capability of the fluid mixture; for example the fluid mixture may comprise less than 2% per weight gelling agent (or thickening agent).

[0254] In an embodiment the heat absorbing material held in the encapsulation element is liquid-based; for example, the heat absorbing material held in the encapsulation element may comprise any one or more of, water, and / or a water-based solution, sodium acetate trihydrate, iron sulfate heptahydrate and / or any other salt hydrates. In an embodiment the heat absorbing material held in the encapsulation element is aqueousbased. In an embodiment in which the heat absorbing material held in the encapsulation element comprises water (or any other cooling fluid) plus gelling agent (or thickening agent) fluid mixture, the fluid mixture may comprise less than 2% per weight gelling agent (or thickening agent). In anembodiment in which the heat absorbing material held in the encapsulation element comprises a water (or any other cooling fluid) plus gelling agent (or thickening agent) fluid mixture, it should be understood that the fluid mixture may comprise any suitable gelling agent (or thickening agent); for example the gelling agent (or thickening agent) may comprise any one or more of, Polyurethanes, acrylic polymers, latex, styrene / butadiene; Clays - attapulgite, bentonite, and / or other montmorillonite clays; Cellulosics - CMC, HMC, HPMC, and / or other chemically substituted cellulose macromolecules; Sulfonates - Sodium or calcium salts; Gums - guar, xanthan, cellulose, locust bean, and / or acacia; Saccharides (hydrocolloids) - kappa / iota carrageenan (potassium activated), pullulan, konjac, and / or alginate; Proteins - Casein, collagen, albumin; Modified castor oil; Organosilicones - Silicone resins, dimethicones, and / or modified silicones. In an embodiment the gelling agent (or thickening agent) may comprise rheology modifiers in the range 0.2% to 2.0% per weight. In an embodiment the heat absorbing material held in the encapsulation element has a composition which is a stable in the temperature range between -20°C and +80°C. In an embodiment the heat absorbing material held in the encapsulation element has a viscosity above 50 000 cps. In an embodiment the heat absorbing material held in the encapsulation element has a viscosity above 50 000 cps in the temperature range -20°C to 80°C.

[0255] In an embodiment in which the battery module further comprises heat absorbing member, the thermally conductive member may further comprise one or more subsidiary portions which extend from the main portion to increase heat transfer from the heat absorbing member to the thermally conductive member. For example, in an embodiment the thermally conductive member comprises a planar main portion which comprises thermally conductive material, and a plurality of subsidiary portions in the form of a plurality of projections each of which comprise thermally conductive material, which extend from the planar main portion towards the heat absorbing member so as to enable more heat transfer from the heat absorbing member to the thermally conductive member. It should be understood that the thermally conductive member is not limitedto requiring projections; the thermally conductive member may comprise any suitable feature or any surface texture that increases the surface area of the thermally conductive member and thus increases the heat transfer from the heat absorbing member to the thermally conductive member.

[0256] In yet another embodiment the heat absorbing member may comprise a main portion and one or more subsidiary portions which extend from the main portion. For example, in an embodiment the heat absorbing member may comprise a planar main portion which comprises thermally conductive material, and a plurality of subsidiary portions in the form of a plurality of projections, each of which comprise thermally conductive material, and each of which extend from the planar main portion. In an embodiment the plurality of projections extend from the main portion towards the thermally conductive member, so as to enable more heat transfer from the heat absorbing member to the thermally conductive member. It should be understood that the heat absorbing member is not limited to requiring projections; the heat absorbing member may comprise any suitable feature or any surface texture that increases the surface area of the heat absorbing member and thus increases the heat transfer from the heat absorbing member to the thermally conductive member.

[0257] In an embodiment the heat absorbing member abuts the thermally conductive member; in this case there is direct physical contact between the heat absorbing member and the thermally conductive member. In another embodiment heat absorbing member is attached to the thermally conductive member by a thermally conductive attachment means, such as a thermally conductive glue. In another embodiment carbon nanotubes are located at an interface between the heat absorbing member and the thermally conductive member. These carbon nanotubes promote the transfer of heat from the heat absorbing member to the thermally conductive member.

[0258] According to a further aspect of the present disclosure there is provided a battery module assembly, which comprises,at least a first and second battery module each of which comprises a plurality of battery cells; and a cooling system which comprises at least one inlet and at least one outlet, and a cooling duct along which a cooling fluid can flow, and wherein the cooling duct is fluidly connected between the at least one inlet and at least one outlet. Cooling fluid flowing in the cooling duct can absorb heat which has been generated by the battery cells in the at least a first and second battery modules.

[0259] In an embodiment the battery module assembly comprise at least one thermally conductive member which is arranged to be in thermal communication with at least one of said battery modules; and the cooling duct is arranged to be in thermal communication with thermally conductive member so that cooling fluid flowing in the cooling duct can absorb heat from the thermally conductive member.

[0260] It should be understood that the at least first and second battery modules in the aforementioned battery assembly may have any one or more of the features of any of the other battery module embodiments described in the present disclosure.

[0261] In an embodiment the at least first and second battery modules are stacked. For example, in an embodiment the at least first and second battery modules are stacked in a head-to-tail disposition.

[0262] It should be understood that any of the battery module embodiments of the present disclosure may further comprise a cooling system; for example, any of the battery module embodiments of the present disclosure may further comprise any of the cooling systems (and variations thereof) described in the present disclosure. The cooling system may take any suitable form. Figures 10a-10g illustrate an exemplary battery module 1000 embodiment which comprises an exemplary cooling system 1001. It should be understood that any of the battery module embodiments of the present disclosure may further comprise the cooling system 1001.The battery module 1000 of Figures 10a-10g has many of the same features as the battery module 100 and like features are awarded the same reference numbers. It should be understood that the battery module 1000 may have any of the features of any of the battery modules described in the present disclosure.

[0263] In the exemplary battery module 1000 shown in Figures 10a-10g the first conductive plate 10a and second conductive plate 10b are arranged at opposite ends of the battery cells 19. The first conductive plate 10a is arranged above the battery cells 19 and the second conductive plate 10b is arranged below the battery cells 19.

[0264] The cooling system 1001 comprises an electrical insultation sheet 1003 which is thermally connected to the second conductive plate 10b. It should be understood that the electrical insultation sheet 1003 is an optional feature of the battery module 1000. The electrical insultation sheet 1003 electrically isolates the second opposite end 19b of the battery cells 19. In the example shown in Figures 10a-10g the electrical insultation sheet 1003 the mounted on / below the second conductive plate 10b. The second conductive plate 10b has openings 1010b' defined therein which allow the electrical insultation sheet 1003 to be in thermal communication with the battery cells 19. In another embodiment the electrical insultation sheet 1003 may be thermally connected to the first conductive plate 10a; the electrical insultation sheet 1003 may be mounted above the first conductive plate 10a; the first conductive plate 10a may have openings defined therein which the electrical insultation sheet 1003 to be in thermal communication with the battery cells 19. The electrical insultation sheet 1003 may be configured to provide a dielectric strength in the range 10V- 2kV; in an embodiment the electrical insultation sheet 1003 is configured to provide an dielectric strength of about 1 kV; in an embodiment the electrical insultation sheet 1003 is configured to provide an dielectric strength of about 100 V. The electrical insultation sheet 1003 may have any suitable thickness; in an embodiment the electrical insultation sheet 1003 has a thickness of 1 mm or less.

[0265] The cooling system 1001 further comprises at least one thermally conductive member 1002 which is arranged to be thermally connected to the battery cells 19. The at least one thermally conductive member 1002 may take any suitable form. In an embodiment the at least one thermally conductive member 1002 comprise any one or more of aluminum, copper, titanium, zinc, or an alloy (e.g. an alloy containing one or more of aluminum, copper, titanium, zinc), and / or any other metal, and / or any other materials such as carbon (such as, reticulated vitreous carbon, for example). In an embodiment the at least one thermally conductive member1002 has a porosity which is 90% or greater. Providing a thermally conductive member 1002 that has high porosity advantageously reduces weight and enables fluid circulation through the thermally conductive member 1002.

[0266] In the example illustrated in Figures 10a-10g the at least one thermally conductive member 1002 is in the form of one or more foam sheets 1002; in the present example the cooling system 1001 of the battery module 1000 is shown to comprises '2' foam sheets 1002, but it should be understood that the cooling system 1001 may comprise any number of foam sheets 1002. The one or more foam sheets 1002 are mounted below the electrical insultation sheet 1003. In the example shown in Figure 10a- 10g the foam sheets 1002 comprise aluminum. However, it should be understood that the one or more foam sheets 1002 may comprise any suitable material; for example, the foam sheets 1002 may comprise any one or more of aluminum, copper, titanium, zinc, or an alloy (e.g. an alloy containing one or more of aluminum, copper, titanium, zinc), and / or any other metal, and / or any other materials such as carbon (such as, reticulated vitreous carbon, for example).

[0267] During use these one or more foam sheets 1002 act as a heat sink as they absorb heat from the electrical insultation sheet 1003 ; more specifically during use the battery cells 19 generate heat - the heat is conducted away from the battery cells 19 by the electrical insultation sheet1003 and in turn is conducted away from the electrical insultation sheet 1003 by the foam sheets 1002. In an embodiment the electrical insultationsheet 1003 is configured to be as thin as possible so as to reduce the heat transfer resistance from the battery cells 19 to the foam sheets 1002 of the cooling system 1001.

[0268] It should be understood that the electrical insultation sheet 1003 is an optional feature of the cooling system 1001. In another embodiment the cooling system 1001 is without the electrical insultation sheet 1003; the thermally conductive member (e.g. said one or more foam sheets 1002) may be mounted on / below the second conductive plate 10b. In which case the at least one thermally conductive member (e.g. said one or more foam sheets 1002) may be in direct thermal communication with the battery cells 19 through the openings 1010b' defined in the first conductive plate 10b.

[0269] The cooling system 1001 further comprises a cooling duct member 1005. The cooling duct member 1005 may be attached to the housing 2 to define a cooling duct 1005' along which cooling fluid can flow. The cooling duct member 1005 is attached to the housing 2 such that the one or more foam sheets 1002 are located within the cooling duct 1005'. The cooling duct member 1005 has one or more inlets 1005a and one or more outlets 1005b. In the present example the cooling duct member1005 comprises '3' inlets 1005a and '2' outlets 1005b. The cooling system further comprises one or more fans 1006; in this specific example '3' fans1006 are provided however it should be understood that the cooling system may comprise any numbers of fans 1006. Each of the '3' inlets are fluidly connected to a respective fan 1006 which is operable to generate a flow of cooling air which passes through the respective inlet 1005a, along the cooling duct 1005', and out the outlets 1005b.

[0270] During use of the battery module 1000 at least some of the heat generated by the battery cells 19 is conducted away from the battery cells 19 by the electrical insultation sheet 1003 and is absorbed by the one or more foam sheets 1002. The fans 1006 are selectively operated to generate a flow of cooling air which passes through the respective inlet 1005a and along the cooling duct 1005'. For example, the fans 1006 may be operablyconnected to the controller 110, and the controller 110 may operate one or more of the fans 1006 to generate a flow of cooling air, if a temperature measurement that the controller 110 receives from the temperature sensors 172 exceeds a predefined temperature threshold. In an embodiment, the controller 110 may operate a first predefined number of the fans 1006 to generate a flow of cooling air, if a temperature measurement that the controller 110 receives from the temperature sensors 172 exceeds a first predefined temperature threshold; and the controller 110 may operate a second predefined number of the fans 1006 to generate a flow of cooling air, if a temperature measurement that the controller 110 receives from the temperature sensors 172 exceeds a second predefined temperature threshold, wherein the first predefined temperature is less than the second predefined temperature, and the first predefined number is less than the second predefined number. In an embodiment the number of the fans 1006 the controller 110 may operate will be proportional to the temperature measurement that the controller 110 receives from the temperature sensors 172.

[0271] As the cooling air passes along the cooling duct 1005' it will cool the one or more foam sheets 1002 - in this way the cooling air absorbs heat energy from the one or more foam sheets 1002 thereby allowing the one or more foam sheets 1002 to absorb more heat from the electrical insultation sheet 1003 and thus allowing the electrical insultation sheet 1003 to provide further cooling of the battery cells 19. As the cooling air absorbs heat energy from the one or more foam sheets 1002 the cooling air will heat; and the heated air is passed out of the cooling duct 1005' via the outlets 1005b. Optionally, the cooling system 1001 may further comprise a heat exchanger which is fluidly connected to the outlets 1005b; after the heated air has been passed out of the cooling duct 1005' the heated air may be passed through the heat exchanger where it is cooled, and then after been cooled may be directed back into the cooling duct 1005' via the inlets 1005a.

[0272] Figure 11a illustrates an exemplary battery module 1111 embodiment which comprises a heat absorbing member 1112. Figure 11 billustrates the heat absorbing member 1112 with a partial cut-away portion, which is used in the exemplary battery module 1111 of Figure 11 a.

[0273] It should be understood that any of that any of the battery module embodiments of the present disclosure may further comprise the heat absorbing member 1112 which is used in the battery module 1111 shown in Figure 11a, or may comprise any of the heat absorbing member variations described in the present disclosure. It should be understood that the battery module 1111 may have any of the features of any of the battery modules described in the present disclosure. The battery module 1111 of Figures 11 a has many of the same features as the battery modules described previously in the present disclosure and like features are awarded the same reference numbers.

[0274] As with the previously described battery module embodiments the battery module 1111 comprises a plurality of battery cells 19. However in the battery module 1111 each of the battery cells 19 are in the form of a pouch battery cell 19. Each pouch battery cell 19 comprises a pouch 1119, and a positive node 1119a and negative node 1119b (which may also be referred to as the negative tap 1119b) which protrude from said pouch. The battery module 1111 comprises a plurality of compressible members 1120; specifically, a respective compressible member 1120 is provided between adjacent pouch battery cells 1119; in an embodiment a compressible member 1120 is provided on either side of each pouch battery cells 1119 (i.e. each pouch battery cell 1119 is flanked by compressible members 1120). Figure 11a shows one of the pouch battery cells 1119 and one compressible member 1120 removed from the battery module 1111 for clarity.

[0275] The compressible members 1120 may be composed of any suitable material; in the exemplary battery module 1111 shown in Figure 11a, each compressible member 1120 comprises an compressible material (e.g. elastically compressible material) which is also thermally insulative. Although it is not essential to the disclosure that each compressiblemember 1120 comprise a thermally insulative material. In an embodiment each compressible member 1120 comprises a foam (for example a compressible foam which is thermally insulating). The compressible members 1120 which are located between the pouch battery cells 19 serve to prevent movement of the pouch battery cells 19 within the battery module 1111. Some, or all of the pouch battery cell 1119 may expand during use; the compressibility of compressible members 1120 allow for the expansion of the pouch battery cells 1119, while still holding the pouch battery cells 1119 in position within the battery module 1111. The thermally insulative properties of the compressible members 1120 will also ensure that heat generate by each respective pouch battery cell 1119 is not conducted to the adjacent pouch battery cells 1119.

[0276] The heat absorbing member 1112 is arranged to be in thermal communication with each of the pouch battery cells 1119 in the battery module 1111. The heat absorbing member 1112 is further in thermal communication with a heat sink 1130. During use heat generated by the pouch battery cells 1119 is absorbed by heat absorbing member 1112; and the heat energy in the heat absorbing member 1112 is conducted to the heat sink 1130 where it is preferably dissipated into the atmosphere. In an embodiment the to the heat sink 1130is arranged to be in thermal communication with the heat absorbing member 1112 and also in thermal communication with all (or at least one) of the pouch battery cells 1119.

[0277] In this example the heat sink 1130 in the form of a metallic plate member having a series of fins 1130a which increase the surface area of the heat sink 1130 to maximize dissipation of heat to the atmosphere. Optionally, an air flow can be provided between the fins 1130a, or a cooling fluid can be flowed between the fins 1130a, which absorbs heat energy from the heat sink 1130; for example the battery module 1111 may further comprise a cooling system, such as the cooling system 1001 of the battery module 1000 of Figures 10a-10g, and the heat sink 1130 may be located within the cooling duct 1005' of the cooling system 1001.

[0278] It should be understood that the battery module 1111 may comprise any number of heat absorbing members 1112; for example, in an embodiment the battery module 1111 comprises a single heat absorbing member 1112; in another embodiment the battery module 1111 comprises a plurality of heat absorbing members 1112.

[0279] Figure 11b provides an illustration of an exemplary heat absorbing member 1112, with a partial cut-away portion, that is used in the battery module 1111 of Figure 11 a. Referring to Figure 11 b, it can be seen that the heat absorbing member 1112 comprises an encapsulation element 1113 which holds a heat absorbing material 1115. The encapsulation element 1113 may comprise flexible, and / or compressible, material; this will allow easy preforming of the encapsulation element 1113 and / or makes the encapsulation element 1113 conformable.

[0280] In this example encapsulation element 1113 comprises a matrix 1113a which holds the heat absorbing material 1115; the matrix 1113a is held within a casing 1113b. In this example the casing 1113b comprises metal; specifically, in this example, the casing 1113b comprises aluminumpolymer laminate. However, it should be understood that the casing 1113b may comprise any suitable material, for example the casing 1113b may comprise any one or more of, aluminum-polymer laminates, and / or nonflammable and / or watertight cloth such as fiber-reinforced polymers. Preferably the casing 111 b comprises thermally conductive material.

[0281] The matrix 1113a may comprise any suitable material. The matrix 1113a preferably comprises thermally conductive material; the matrix can then serve to enhance the conduction of heat from the casing 1113b into the heat absorbing material 1115 that is held within the encapsulation element 1113. For example the matrix 1113a may comprise any one or more of: graphite (e.g. expanded graphite), and / or aerogel, and / or nonwoven carbon fiber, and / or glass fiber, and / or carbon, and / or carbon fiber, and / or metal (e.g. in the form of wire), and / or metal alloy, and / or polymer,and / or any other suitable material. In the example shown in Figure 11 b the matrix 1113a comprises non-woven carbon material.

[0282] The heat absorbing material 1115 may be held within the casing 1113b and / or within the matrix 1113a; for example the heat absorbing material 1115 may be held within a volume define by the casing 1113b, and / or may be within pores or spaces that are within the matrix 1113a (for example the heat absorbing material 1115 may be impregnated into the matrix 1113a). The heat absorbing material 1115 may be further provided outside of the matrix 1113a and with the volume defined by the casing 1113b. In the example illustrated in Figure 11 b the heat absorbing material 1115 is contained (impregnated) within the matrix 1113a and it also outside of the matrix 1113a but contained within the volume defined by the casing 1113b.

[0283] The heat absorbing material 1115 held in the encapsulation element 1113 is a material which can undergo a phase change when heated e.g. the heat absorbing material 1115 may be a material which can undergo a phase change when heated to a predefined temperature. In the exemplary embodiment the heat absorbing material 1115 comprises water. Advantageously water has a superior phase change enthalpy and vaporization temperature at 100°C, which is above nominal use temperatures of the pouch battery cells 1119 in the battery module 1111, but below thermal runaway trigger temperature. Water is also nonflammable, has the highest latent heat capacity, and a phase transition at 100°C, which is conveniently above nominal use temperatures of the pouch battery cells 1119 in the battery module 1111, but below thermal runaway trigger temperature. In an embodiment the encapsulation element 1113 contains between 5g-50g of water; in an embodiment the encapsulation element 1113 contains 15 g of water.

[0284] The typical dimensions of the heat absorbing member 1112 are usually defined by the dimensions of the pouch battery cells 1119 and the cell coverage per pouch; in one embodiment the heat absorbing member1112 may be approximately 60 mm wide and 150mm long (so that heat absorbing member 1112 may be in contact with the length of the pouch battery cells 1119, and may wrap around three pouch battery cells 1119).

[0285] It should be understood that the heat absorbing member 1112 may take any suitable form: for example, in another embodiment the heat absorbing member 1112 comprises an encapsulation element 1113 which comprises a plurality of pouches each of which hold heat absorbing material; in another embodiment the heat absorbing member 1112 comprises an encapsulation element 1113 which defines a single pouch which holds heat absorbing material; in another embodiment the heat absorbing member 1112 comprises an encapsulation element 1113 comprises a matrix (such as the matrix 1113a for example) and the heat absorbing material 1115 is impregnated in the matrix and further comprises a plurality of pouches each of which hold heat absorbing material; in another embodiment the heat absorbing member 1112 comprises an encapsulation element 1113 which forms a matrix (such as the matrix 1113a for example) and the heat absorbing material 1115 is impregnated in the matrix and wherein the encapsulation element further defines a single pouch which holds heat absorbing material 1115. In an embodiment each of the plurality of pouches, or single pouch, of the encapsulation element 1113 is configured to be air-tight (in other words the heat absorbing material 1115 is held, air-tight, in encapsulation element 1113). In an embodiment the encapsulation element 1113 comprises material which is self-extinguishing. In an embodiment the encapsulation element 1113 comprises a metal which is configured and arranged to form a radiation barrier. In an embodiment the encapsulation element 1113 comprises electrically insulating material. In an embodiment the encapsulation element 1113 comprises thermally conductive material. In an embodiment the encapsulation element 1113 comprises material which is both electrically insulating and thermally conductive. The encapsulation element 1113 may comprise any one or more of, aluminum-polymer laminates, and / or non-flammable and / or watertight cloth such as fiber-reinforced polymers. In an embodiment in which the encapsulation element 1113 comprises a plurality of pouches, or is configured to define a single pouch,then encapsulation element 1113 may comprise any one or more of, aluminum-polymer laminates, and / or non-flammable and / or watertight cloth such as fiber-reinforced polymers. The encapsulation element 1113 may comprise any one or more of, graphite (e.g. expanded graphite) and / or aerogel and / or non-woven carbon fiber and / or glass fiber. In an embodiment in which the encapsulation element comprises a matrix (such as the matrix 1113a for example) and the heat absorbing material 1115 is impregnated in the matrix, then the encapsulation element 1113 may comprise a matrix which comprises any one or more of, graphite (e.g. expanded graphite) and / or aerogel and / or non-woven carbon fiber and / or glass fiber.

[0286] The heat absorbing material 1115 held in the encapsulation element 1113 may take any suitable form: In an embodiment the heat absorbing material 1115 is a solid in its initial state, and changes phase to a liquid (fusion) and / or gas when heated to a predefined temperature; in another embodiment the heat absorbing material 1115 is a fluid (such as a liquid or gel) in its initial state, and changes phase to a gas (vaporization) when heated to a predefined temperature; heat energy is absorbed through latent heat capacity. In another embodiment the heat absorbing material 1115 held in the encapsulation element 1113 is a material which can undergo a chemical phase transition when heated e.g. the heat absorbing material may be a material which can undergo a chemical phase transition when heated to a predefined temperature; the chemical phase transition may be a chemical phase transition involving structural water release (in the form of vapor), and / or a glass transition, and / or any other chemical transformations such as decomposition (wherein heat is absorbed through reaction enthalpy). In an embodiment the heat absorbing material 1115 is configured to significant heat in nominal use of the battery module 1111, so as to homogenize the temperature of the pouch battery cells 19 in the battery module 1111 (and thereby ensuring that the battery cells in the battery module age more uniformly), with discrete or latent heat absorption. In an embodiment the heat absorbing material 1115 is configured to absorb the majority of the heat generated by the pouch battery cells 19 in the battery module 1111, between the maximumnominal operation temperature and the thermal runaway temperature (so as to effectively mitigate thermal runaway propagation). In an embodiment the heat absorbing material 1115 is dimensioned to absorb enough excess heat generated by each of the pouch battery cells 19 during use, that would otherwise trigger the thermal runaway of other the pouch battery cells 19 in the battery module 1111.

[0287] The heat absorbing material 1115 held in the encapsulation element 1113 may be configured to absorb part or the totality of the heat of the pouch battery cells 19 by the gradual increase of temperature of the heat absorbing material 1115, defined as discrete heat, and characterized by the heat capacity of the heat absorbing material 1115. In an embodiment the heat absorbing material 1115 comprises non-flammable or self-extinguishing material. In an embodiment the heat absorbing material 1115 held in the encapsulation element 1113 comprises water (or any other cooling fluid) plus a gelling agent (or thickening agent) fluid mixture which can absorb heat energy and which can undergo a phase change when heated above a predefined temperature. Advantageously, in this embodiment in which the heat absorbing material 1115 comprises a gelling agent (or thickening agent), if for example a pouch of the encapsulation element 1113 is pierced the gelling agent will ensure that the fluid mixture does not flow out through the hole in the pouch. It should be understood that any suitable gelling agent may be used. Typically only in the low fraction of gelling agent (or thickening agent) is used in the fluid mixture in order decrease the risk of leakage our of a pierced pouch, which does not compromise significantly the heat absorption capability of the fluid mixture.

[0288] The heat absorbing material 1115 held in the encapsulation element 1113 may have any suitable composition. In an embodiment the heat absorbing material 1115 held in the encapsulation element 1113 is liquid-based; for example the heat absorbing material 1115 held in the encapsulation element 1113 may comprise any one or more of, water, and / or a water-based solution, sodium acetate trihydrate, iron sulfate heptahydrate and / or any other salt hydrates. In an embodiment the heatabsorbing material 1115 held in the encapsulation element 1113 is aqueous-based. In an embodiment in which the heat absorbing material 1115 held in the encapsulation element 1113 comprises water (or any other cooling fluid) plus gelling agent (or thickening agent) fluid mixture, the fluid mixture may comprise less than 2% per weight gelling agent (or thickening agent). In an embodiment in which the heat absorbing material 1115 held in the encapsulation element 1113 comprises water (or any other cooling fluid) plus gelling agent (or thickening agent) fluid mixture; it should be understood that the fluid mixture may comprise any suitable gelling agent (or thickening agent); for example the gelling agent (or thickening agent) may comprise any one or more of, Polyurethanes, acrylic polymers, latex, styrene / butadiene; Clays - attapulgite, bentonite, and / or other montmorillonite clays; Cellulosics - CMC, HMC, HPMC, and / or other chemically substituted cellulose macromolecules; Sulfonates - Sodium or calcium salts; Gums - guar, xanthan, cellulose, locust bean, and / or acacia; Saccharides (hydrocolloids) - kappa / iota carrageenan (potassium activated), pullulan, konjac, and / or alginate; Proteins - Casein, collagen, albumin; Modified castor oil; Organosilicones - Silicone resins, dimethicones, and / or modified silicones. In an embodiment the gelling agent (or thickening agent) may comprise rheology modifiers in the range 0.2% to 2.0% per weight. In an embodiment the heat absorbing material 1115 is configured to have a composition which is a stable in the temperature range between - 20°C and +80°C. In an embodiment the heat absorbing material has a viscosity above 50 000 cps. In an embodiment the heat absorbing material held in the encapsulation element has a viscosity above 50 000 cps in the temperature range -20°C to 80°C.

[0289] During use of the battery module 1111 at least some of the heat generated by the pouch battery cells 19 is conducted away from the pouch battery cells 19 by the heat absorbing member 1112; more specifically heat produced by the pouch battery cells 19 will be conducted way from the pouch battery cells 19 by the thermally conductive casing 1113b of the encapsulation element 1113; said heat will be conducted from the casing 1113b to the matrix 1113a of the of the encapsulation element 1113. Since the matrix 1113a comprises thermally conductive material, the matrix 1113awill enhance the conduction of heat from the casing 1113b of the encapsulation element 1113 into the heat absorbing material 1115 (which in this example is water) which is contained within the matrix 1113a. The heat absorbing material 1115 (which in this example is water) will undergo a phase change thereby dissipating the heat energy; specifically, when the water is heated to 100°C it will vaporize - heat energy will be dissipated in the water due to the latent heat of vaporization. 100°C is above nominal use temperatures of the pouch battery cells 1119 in the battery module 1111, but below thermal runaway trigger temperature, accordingly the water will help to prevent the occurrence of thermal runaway. At least some of the heat energy in the heat absorbing member 1112 may be conducted away from the heat absorbing member 1112 into the heat sink 1130 where it is dissipated into the atmosphere, thereby enabling the heat absorbing member 1112 to conduct more heat energy from the pouch battery cells 19.

[0290] It should be understood that any of the battery module embodiments of the present disclosure may be used to power an electric vehicle, such as electric or hybrid aircraft. Therefore, according to a further aspect of the present disclosure there is provided an electric vehicle which comprises a battery module according to any of the embodiments described in the present application. Preferably the electric vehicle is an electric aircraft, or a hybrid aircraft.

[0291] Various modifications and variations to the described embodiments of the disclosure will be apparent to those skilled in the art without departing from the scope of the disclosure as defined in the appended claims. Although the disclosure has been described in connection with specific preferred embodiments, it should be understood that the disclosure as claimed should not be unduly limited to such specific embodiment.

Claims

Claims1. A battery module (1111) which comprises, a plurality of battery cells (19); and at least one heat absorbing member (1112) which is arranged to be in thermal communication with the plurality of battery cells, and wherein the at least one heat absorbing member (1112) comprises heat absorbing material (1115) comprises a material which can undergo a phase change when heated.

2. A battery module according to claim 1 wherein the plurality of battery cells comprise pouch battery cells.

3. A battery module according to any one of claims 1 or 2wherein the at least one heat absorbing member comprises an encapsulation element which holds said heat absorbing material.

4. A battery module according to any one of the preceding claims wherein the heat absorbing material comprises a material which can undergo a phase change when heated to a predefined temperature.

5. A battery module according to any one of the preceding claims wherein encapsulation element comprises a matrix which holds the heat absorbing material.

6. A battery module according to claim 5 wherein the heat absorbing material is impregnated into the matrix.

7. A battery module according to claim 5 or 6 wherein the matrix comprises thermally conductive material.

8. A battery module according to any one of claims 5 - 7 wherein the matrix comprises any one or more of: graphite, and / or aerogel, and / or nonwoven carbon fiber, and / or glass fiber, and / or carbon, and / or carbon fiber, and / or metal, and / or metal alloy, and / or polymer.

9. A battery module according to any one of claims 5 -8 wherein the encapsulation element further comprises a casing and wherein the matrix is held within a volume defined by the casing.

10. A battery module according to claim 9 wherein heat absorbing material is further provided outside of the matrix within the volume defined by the casing.11.A battery module according to claim 9 or 10 wherein the casing comprises thermally conductive material12. A battery module according to any one of claims 9 - 11 wherein the casing comprises any one or more of: aluminum-polymer laminates, and / or non-flammable and / or watertight cloth such as fiber-reinforced polymers.

13. A battery module according to any one of claims 3-4 wherein encapsulation element comprises a plurality of pouches each of which hold the heat absorbing material.

14. A battery module according to claim 13 wherein each pouch is air-tight.

15. A battery module according to claim 13 or 14 wherein the encapsulation element comprises thermally conductive material.

16. A battery module according to any one of claims 13-15 wherein the encapsulation element comprises any one or more of: aluminum-polymer laminates, and / or non-flammable and / or watertight cloth such as fiber- reinforced polymers.

17. A battery module according to any one of claims 13-16 wherein the heat absorbing material further comprises a gelling agent and / or a thickening agent.

18. A battery module according to any one of claims 1-17 wherein the heat absorbing material is liquid-based.

19. A battery module according to any one of claims 1-18 wherein the heat absorbing material is aqueous-based.

20. A battery module according to any one of claims 1-19 wherein the heat absorbing material comprises any one or more of, water, and / or a waterbased solution, sodium acetate trihydrate, iron sulfate heptahydrate and / or any other salt hydrates.

21. A battery module according to any one of claims 1-20 further comprising one or more compressible members which are arranged in the battery module to prevent movement of the battery cells within the battery module, an which are configured to be compressible by swelling of the battery cells.

22. A battery module according to claim 21 wherein compressible members arranged on either side of each battery cell so that each battery cell is flanked by compressible members.

23. A battery module according to any one of claims 21-22 wherein each compressible member comprises a material which is compressible and thermally insulative.

24. A battery module according to any one of claims 1-23 further comprising a heat sink which is arranged to be in thermal communication with the at least one heat absorbing member.

25. An electric vehicle comprising a battery module according to anyone of claims 1-24.

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