Description:TECHNICAL FIELD
[0001] The present subject matter relates in general to a battery pack. More particularly but not exclusively the present subject matter relates to a fire-resistant battery pack and a method for manufacturing a battery pack which reduces the 5 propagation of fire in battery packs.
BACKGROUND
[0002] The imperative pressure built on electrical energy storage devices in the 21st century is corollary linked with critical concerns of safety with reference to potential fire hazards. The fire hazards witnessed in electrical energy storage 10 devices such as battery packs are a result of thermal runaway occurring in the cells of the battery pack.
[0003] In light of frequently witnessed fire incidents in electrical energy storage devices, there is a dire need for the development of improved safety mechanisms for critical parts such as the battery packs used in electric vehicles (hereinafter 15 referred to as EVs), with safety mechanisms being directed at reducing the propagation of fires from the battery achieved by confinement of the fire mishap.
[0004] Thermal runaway refers to an accelerated release of heat inside a cell of the battery pack due to uncontrolled exothermic reactions. In scenarios of uncontrolled exothermic reactions, the cells can no longer dissipate the heat as 20 quickly as the heat is generated in the cell, ultimately leading to a loss of thermal stability of the cell. The heat generated in the malfunctioning cell during thermal runaway can propagate to neighboring cells, which would then trigger thermal runaway in the adjacent cells leading to catastrophic failure in the entire battery pack. Upon failure due to thermal runaway, the massive heat contained in the 25 battery pack may spark leading to a fire bursting out from the battery pack.
[0005] Lithium-ion batteries (hereinafter referred to as LIBs), have features such as high energy density, high power density, excellent cycle performance and environmental friendliness, and are widely used in energy storage systems for EVs and other electrical or electronic machinery. However, LIBs have great 30 propensity of catastrophic failure in events of thermal runaway as the heat energy
released from a single failing LIB cell during thermal runaway can cause a chain reaction in the neighboring LIB cells. [0006] In view of potential loss of life and property owing to thermal runaway in battery packs there are well-established regulatory norms pertaining to confinement of the fire hazard to develop battery packs with improved safety.
5
[0007] Thus, there is a requirement of an effective fire-resistant battery pack which prevents the propagation of heat from the malfunctioning cell of the battery pack to the adjacent cells of the battery pack in compliance with regulations and safety practices.
SUMMARY OF THE INVENTION 10
[0008] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
[0009] According to embodiments illustrated herein, the present invention 15 provides a battery pack comprising a plurality of cells, a first material and an external casing. The plurality of cells comprising a pre-defined pattern of disposition in the battery pack. The first material is configured to cover a first pre-defined surface area of each cell of the plurality of cells, wherein the first material is a thermally insulative material. The external casing is configured to enclose at 20 least the plurality of cells and the first material.
[00010] According to embodiments illustrated herein, the present invention additionally provides the battery pack to comprise of a second material. The second material is configured to cover a second pre-defined surface area of the each cell of the plurality of cells, wherein the second material being a thermally 25 conductive material. The battery pack comprising the plurality of cells, the first material and the second material being enclosed by the external casing.
[00011] According to embodiments illustrated herein, the present invention also provides a method for manufacturing of a battery pack comprising steps: disposing, a plurality of cells in an external casing of the battery pack; adding, a 30
first material into the external casing disposed with the plurality of cells; curing, the first material in the external casing over a first pre-defined period of time; adding, a second material into the external casing; curing, the second material in the external casing over a second pre-defined period of time; and enclosing, the external casing comprising of the plurality of cells, the first material and the 5 second material from an open surface. In an aspect, the plurality of cells is disposed on the external casing in a pre-defined pattern. In another aspect, a first pre-defined volume of the first material is added into the external casing to cover a first pre-defined surface area of the plurality of cells. In another aspect, a second pre-defined volume of the second material is poured into the external casing to 10 cover a second pre-defined surface area of the plurality of cells.
BRIEF DESCRIPTION OF THE DRAWINGS
[00012] The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present 15 invention, and therein.
[00013] The detailed description is described with reference to the accompanying figures, which is related to a battery pack. However, the present subject matter is not limited to the depicted embodiment(s). In the figures, the same or similar numbers are used throughout to reference features and components. 20
[00014] Figure 1 exemplarily illustrates a fire-resistant battery pack in accordance with some embodiments of the present disclosure.
[00015] Figure 2 illustrates an exploded top perspective view of one or more components of the fire-resistant battery pack in accordance with some embodiments of the present disclosure. 25
[00016] Figure 3 illustrates an exploded top perspective view of one or more components of the fire-resistant battery pack in accordance with some embodiments of the present disclosure.
[00017] Figure 4 illustrates a fire-resistant battery pack comprising of a first material and a second material in accordance with some embodiments of the present disclosure.
[00018] Figure 5 illustrates a method for manufacturing a fire-resistant battery pack in accordance with the embodiments of the present disclosure. 5
DETAILED DESCRIPTION
[00019] The present disclosure may be best understood with reference to the detailed figures and description set forth herein. Various embodiments are discussed below with reference to the figures. However, those skilled in the art will readily appreciate that the detailed descriptions given herein with respect to 10 the figures are simply for explanatory purposes as the methods and systems may extend beyond the described embodiments. For example, the teachings presented and the needs of a particular application may yield multiple alternative and suitable approaches to implement the functionality of any detail described herein. Therefore, any approach may extend beyond the particular implementation 15 choices in the following embodiments described and shown.
[00020] References to “one embodiment,” “at least one embodiment,” “an embodiment,” “one example,” “an example,” “for example,” and so on indicate that the embodiment(s) or example(s) may include a particular feature, structure, characteristic, property, element, or limitation but that not every embodiment or 20 example necessarily includes that particular feature, structure, characteristic, property, element, or limitation. Further, repeated use of the phrase “in an embodiment” does not necessarily refer to the same embodiment.
[00021] The present invention now will be described more fully hereinafter with different embodiments. This invention may, however, be embodied in many 25 different forms and should not be construed as limited to the embodiments set forth herein; rather those embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the invention to those skilled in the art.
[00022] The present subject matter is further described with reference to 30 accompanying figures. It should be noted that the description and figures merely
illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof. 5 [00023] Various features and embodiments of the present subject matter here will be discernible from the following further description thereof, set out hereunder. It is contemplated that the concepts of the present subject matter may be applied to any kind of electrical equipment or vehicle within the spirit and scope of this subject matter. The detailed explanation of the constitution of parts other than the 10 present subject matter which constitutes an essential part has been omitted at suitable places.
[00024] The present invention is illustrated with a battery pack. However, a person skilled in the art would appreciate that the present invention is not limited to a battery pack and certain features, aspects and advantages of embodiments of 15 the present invention can be extended to other forms of energy storage devices used with various types of vehicles such as vehicles having internal combustion engines, electric vehicle and hybrid vehicles, and other forms of electrical and electronic equipment requiring an energy storage device. In an embodiment, the battery pack is configured to supply electrical energy to an external electrical load. 20
[00025] It is an object of the present subject matter to provide a fire-resistant battery pack which prevents the propagation of thermal runaways occurring in battery packs.
[00026] To this end, the present subject matter provides a fire-resistant battery pack comprising of a plurality of cells disposed in a pre-defined pattern in a 25 battery pack and enclosed by an external casing. In accordance with the present disclosure, a first material is configured to cover a first pre-defined surface area of each cell of the plurality of cells of the battery pack. The first material is a thermally insulative material and is adapted to absorb heat. In the event of thermal runaway, a malfunctioning cell of the battery pack generates heat, this heat is 30 absorbed by the first material. In the event a fire is sparked in the malfunctioning
cell, the propagation of the fire from the malfunctioning cell to the adjacent cells is restricted by provision of the first material covering the first pre-defined surface area of the malfunctioning cell. [00027] Additionally, the malfunctioning cell may exude undesirable gases which are required to be vented out. An additional material property of the first material 5 provides porosity which allows the exuded undesirable gases to diffuse towards a venting portion of the battery pack facilitating the removal of undesirable gases from the battery pack. In an embodiment, the entire surface area of each cell of the plurality of cells of the battery pack is covered by the first material.
[00028] The achieved functionality of the battery pack comprising of the first 10 material abates the possibility of catastrophic failure by limiting fire propagation within the battery pack and additionally facilitating venting out of undesirable gases within the battery pack.
[00029] It is an object of the present subject matter to prevent propagation of thermal runaways from one malfunctioning cell to adjacent cells of the battery 15 pack.
[00030] In accordance with the present disclosure, the first material is configured to cover a first pre-defined surface area of each cell of the plurality of cells comprising the battery pack. In the event of over-heating in a malfunctioning cell, the first material covering the malfunctioning cell absorbs the heat and limits the 20 possibility of fire sparking in the malfunctioning cell. Additionally, even if fire sparks in the malfunctioning cell, the propagation of the fire to the adjacent cells is constricted by the first material. In an embodiment, the first material covers 70% to 80% of the surface area of each cell of the plurality of cells of the battery pack. 25
[00031] It is an object of the present subject matter to provide effective thermal management in a battery pack in the event of thermal runaway occurring in the battery pack.
[00032] To this end, the battery pack in accordance with the present disclosure additionally comprises of a second material configured to cover a second pre-30 defined surface area of each cell of the plurality of cells. The second material is a
thermally conductive material which can transmit the heat in the plurality of cells of the battery pack to a side or surface of the external casing having a plurality of fins or other forms of heat dissipating members. The thermal conductivity of the second material ensures effective heat dissipation from one side of the external casing leading to a more efficient and effective thermal management in the battery 5 pack. In an embodiment, the second material covers 20% to 30% of surface area of each cell of the plurality of cells. [00033] In accordance with the disclosed configuration, the first material interfaces with a first side of the external casing which additionally comprises of one or more venting valves thus serving as the venting portion of the battery pack. 10 On the other hand, the second material interfaces with a second side of the external casing comprising a plurality of fins thus serving as a heat dissipating portion of the battery pack. The coordinated operation of the first material and second material in venting and heat dissipation achieves a coherent method of thermal management in the battery pack. 15
[00034] In some known arts concerning thermal management in battery packs, a plurality of thermistors is employed which constantly detect temperature of the cells of the battery pack connected to a control unit. In the event, the temperature in the cells of the battery pack exceeding a threshold temperature, a coping mechanism is deployed to prevent the propagation of fire in the battery pack. In 20 conventional thermal management systems employing a plurality of thermistor with a control unit, would entail complex electronics and would also lead to high maintenance, serviceability and implementation costs.
[00035] The present subject matter negates the requirement of complex electronics, thus providing an economic yet feasible thermal management in the 25 battery pack.
[00036] Additionally, in battery packs using conventional thermal management systems the coping mechanism for isolating and preventing fire propagation is only activated upon the temperature inside the battery pack exceeding a threshold temperature, this creates an unnecessary system latency. 30
[00037] In accordance with the present disclosure, each cell of the battery pack is covered by the first material in a first pre-defined surface area and the second material in the second pre-defined surface area. Under minimal changes in temperature or heat generation, the first material being a thermally insulating material absorbs the heat while the second material being a thermally conductive 5 material dissipates the heat inside the battery pack through a plurality of fins. The present subject matter thus ensures almost instantaneous operations of heat absorption and heat dissipation without waiting for the temperature inside the battery pack to reach a temperature threshold. The present subject matter thus provides an expeditious response to thermal runaway in juxtaposition to thermal 10 management systems in conventional battery packs.
[00038] An ancillary technical advantage in accordance with the disclosed configuration of the battery pack comprising of the first material and the second material covering a first pre-defined surface area and a second pre-defined surface area, respectively of each cell of the battery pack establishes a resilient battery 15 pack. The resilience adapted in the battery pack owing to the first material and the second material enables the battery pack to withstand external environmental loads and vibrational shocks. The first material having a porous texture creates a cushioning effect internally between the adjacent cells of the plurality of cells of the battery pack which ensures secure positioning of each cell and alleviates the 20 transmission of vibrational stresses or shocks between adjacent cells. The disclosed configuration as per the present subject matter ensures secure positioning of the cells in combination with the plurality of cell holders (212) disposed in the battery pack.
[00039] Further, the method for manufacturing the fire-resistant battery pack in 25 accordance with the present disclosure, does not require major revamping of core manufacturing processes. The core manufacturing process pertinent to the manufacturing of components such as the cells of the battery pack, the external casing, the one or more interconnectors (210), the cell holders (212) and other generic equipment remain the same. 30
[00040] The present subject matter along with all the accompanying embodiments and their other advantages would be described in greater detail in conjunction with the figures in the following paragraphs.
[00041] The present subject matter discloses a battery pack comprising a plurality of cells. The battery pack further comprises a first material wherein the first 5 material is configured to cover a first pre-defined surface area of each cell of the plurality of cells of the battery pack. The first material is a thermally insulative material. In an embodiment, the entire surface area of each cell of the plurality of cells is covered by the first material.
[00042] In another embodiment, the battery pack additionally comprises a second 10 material wherein the second material is configured to cover a second pre-defined surface area of each cell of the plurality of cells of the battery pack. The second material is a thermally conductive material.
[00043] The present subject matter comprising of the first material and the second material covering the entire surface area of each cell of the plurality of cells of the 15 battery pack, provides an efficient, expeditious yet cost-effective thermal management solution in battery pack in prevention of propagation of fire from a malfunctioning cell to adjacent cells of the battery pack.
[00044] The present subject matter is further described with reference to accompanying figures. It should be noted that the description and figures merely 20 illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof. 25
[00045] The present subject matter may be implemented in any form of energy storage devices. However, for the purpose of explanation and by no limitation, the present invention, and corresponding additional advantages and features are described through the following embodiments depicting a battery pack.
[00046] Figure 1 exemplarily illustrates a fire-resistant battery pack in accordance 30 with some embodiments of the present disclosure.
[00047] With reference to Figure 1, 100 denotes a battery pack in an assembled view.
[00048] In an aspect, the term “battery pack” (100) used in the present disclosure shall be construed to include any electrical equipment configured to store electrical energy and may include a plurality of battery cells, a plurality of battery 5 modules or other forms of electrical energy storage equipment. The battery pack (100) is configured to be a source of electrical energy which is supplied to an electrical load for its functioning. The battery pack (100) consists of a plurality of cells which are electrically connected in parallel, series or a combined configuration of parallel and series, based on the requisite power output and 10 current output to be supplied by the battery pack (100). The battery pack (100) may be employed in a broad spectrum of industrial applications and equipment and are also serve as a critical component in internal combustion engine-based vehicles, electric vehicles and hybrid vehicle’s development and functioning.
[00049] In an aspect, the battery pack (100) may be rechargeable or non-15 rechargeable dependent on the application for which the battery pack (100) is used. The battery pack (100) has a charged and a discharged state.
[00050] In an aspect, the plurality of cells is disposed in one or more cell holders which hold each cell of the plurality of cells in the required position to maintain cell arrangement and cell spacing. The battery pack (100) includes one or more 20 interconnectors which establish an electrical connection between the plurality of cells disposed in a battery pack (100).
[00051] In an embodiment, the battery pack (100) comprises a battery management system and other suitable circuitry interfaces, and/or code that is configured to work in cooperation with the battery pack (100). 25
[00052] Figure 2 illustrates an exploded top perspective view of one or more components of the fire-resistant battery pack in accordance with some embodiments of the present disclosure.
[00053] Figure 3 illustrates an exploded top perspective view of one or more components of the fire-resistant battery pack in accordance with some embodiments of the present disclosure.
[00054] For the sake of brevity, Figure 2 and Figure 3 shall be explained in conjunction. 5
[00055] With reference to figure 2 and figure 3, 202a and 202b denotes an external casing of the battery pack, 204 denotes a plurality of cells, 206 denotes a first material, 208 denotes a second material, 210 denotes one or more interconnectors and 212 denotes a cell holder.
[00056] The battery pack (100) comprises of the plurality of cells (204) covered 10 by the first material (206) and the second material (208) enclosed in the external casing (202a, 202b).
[00057] The external casing (202a, 202b) comprises of a top cover (202a) and a bottom cover (202b) configured to interface with each other along a plurality of sides of each the top cover (202a) and the bottom cover (202b). The top cover 15 (202a) and bottom cover (202b) are structurally connected along the plurality of sides to ensure secure confinement of the components disposed inside the battery pack (100).
[00058] In an embodiment, the plurality of sides of the top cover (202a) and the bottom cover (202b) comprises of one or more mounting provisions configured to 20 receive one or more fastening units to secure the structural connection between the top cover (202a) and the bottom cover (202b).
[00059] In an aspect, the top cover (202a) of the external casing (202a, 202b) comprises of one or more slots configured to surround one or more venting valves of the battery pack (100). 25
[00060] In an embodiment, the external casing (202a, 202b) is configured to enclose at least the plurality of cells (204) and the first material (206). In another embodiment, the external casing (202a, 202b) is configured to enclose at least the plurality of cells (204), the first material (206) and the second material (208).
[00061] In an embodiment, the external casing (202a, 202b) is composed of a material being at least one of plastic, aluminum, copper, nickel, zinc, stainless steel.
[00062] The plurality of cells (204) relates to electrochemical cells or a combination of electrochemical cells. In an embodiment, each cell of the plurality 5 of cells (204) as depicted in Figure 2 and Figure 3 comprises of one or more electrochemical cells being electrically connected in series connection, parallel connection or a combination of series and parallel connection.
[00063] As depicted in Figure 3, one or more interconnectors (210) is used to establish electrical connection between the plurality of cells (204) of the battery 10 pack (100). Based on the series connection, parallel connection or combination of series and parallel connection established between the plurality of cells (204), the one or more interconnectors (210) are disposed on the plurality of cells (204) to achieve the requisite voltage, current and power outputs.
[00064] Each cell of the plurality of cells (204) comprises of a positive terminal 15 and a negative terminal where current flows from the positive terminal of the cell to the negative terminal through a circuit. Conventionally, the positive terminal of the cell is represented by a protrusion extending from the surface of the cell provided with a metal cap while the negative terminal of the cell is represented by a metal disc disposed on the surface opposite to the metal cap. 20
[00065] In an aspect, the plurality of cells (204) is disposed inside the battery pack (100) wherein the plurality of cells (204) being disposed in a pre-defined pattern. The pre-defined pattern being when the positive terminal of each cell of plurality of cells (204) interfacing with a first side of the plurality of sides of the external casing while the negative terminal of each cell of the plurality of cells (204) 25 interfacing with a second side of the plurality of sides of the external casing. In an embodiment, the first side of the external casing (202a, 202b) is disposed opposite to the second side of the external casing (202a, 202b). In another embodiment, the first side is a surface of the top cover (202a) of the external casing (202a, 202b)
while the second side is a surface of the bottom cover (202b) of the external casing (202a, 202b). [00066] In an aspect, the pre-defined pattern of disposition of the plurality of cells (204) is achieved by single side welding. In an embodiment, the pre-defined pattern of disposition of the plurality of cells (204) is achieved by double sided
5 welding. The single side welding as well as the double side welding may be achieved by at least one of spot welding, laser welding, gas metal arc welding, gas tungsten arc welding, shielded metal arc welding and flux cored arc welding.
[00067] In an embodiment, the pre-defined pattern of disposition of the plurality of cells (204) includes a combination of the positive terminals and negative 10 terminals of the plurality of cells (204) disposed on a first side of the external casing (202a, 202b) while the remnant combination of negative terminals and positive terminals of the plurality of cells (204) is disposed on a second side of the external casing (202a, 202b). In the disclosed configuration of combination of positive terminals and negative terminals of the pre-defined pattern is based on the 15 series connection, parallel connection and/or combined connection to achieve the requisite current, power and voltage output.
[00068] As depicted in Figure 3, a cell holder (212) ensures secure and precise mounting of the one or more cells of the plurality of cells (204) of the battery pack (100). The cell holder (212) secures mounting of each cell in the pre-defined 20 pattern. Aspects of cell holder construction are configured to ensure precise cell spacing between adjacent cells of the plurality of cells (204) of the battery pack (100). In an embodiment, the cell holder (212) is composed of plastic material. In an embodiment, the cell holder (212) comprises of a plurality of compartments that receives the plurality of cells (204). Th cell holder (212) may be mounted 25 onto the external casing (202a, 202b) of the battery pack using fastening units such as screws, eyelets or even adhesive tape.
[00069] In an aspect, a first pre-defined surface area of each cell of the plurality of cells (204) is covered by a first material (206) wherein the first material (206) is a thermally insulative material. An additional material property of the first material 30
(206) is that it is adapted to absorb heat if any is generated in a malfunctioning cell of the plurality of cells (204). An additional material property is the porous texture of the first material (206) which provide internal channels through its pores for directing the diffusion of gases. [00070] In an aspect, the first material (206) is configured to interface with at least
5 a first side of the external casing (202a, 202b) wherein the first side is configured to function as the venting portion. The venting portion comprises of one or more venting valves which assist in expelling undesirable gases inside the battery pack (100).
[00071] With reference to flammability of the first material (206), the first 10 material (206) when subjected to a flame stops burning within 10 second on a vertical part of the first material (206) allowing for drops of plastic that are not inflames. In another aspect with reference to flammability of the first material (206), the burning stops within 60 seconds on a vertical part of the first material (206) not allowing for drops of plastic that are not inflames, where the first 15 material (206) may not have a burn-through.
[00072] In an aspect, a second pre-defined surface area of each cell of the plurality of cells (204) is covered by a second material (208) wherein the second material (208) is a thermally conductive material.
[00073] In an aspect, the second material (208) is configured to interface with at 20 least a second side of the external casing (202a, 202b) wherein the second side is configured to function as the heat radiating portion. The second side comprises of a plurality of fins and other heat radiating units.
[00074] In operation, in the event of thermal runaway occurring in a malfunctioning cell of the plurality of cells (204) of the battery pack (100), a 25 tremendous amount of heat is generated internal to the battery pack (100). The first material (206) covering the first pre-defined surface area of each cell of the plurality of cells (204) initially absorbs the heat generated by the malfunctioning cell. Additionally, the propagation of heat from the malfunctioning cell to the
adjacent cells is restrained owing to the disclosed configuration of the first material (206) covering the first pre-defined surface area of the malfunctioning cell. [00075] In later stages of thermal runaway, owing to the heat generated in the battery pack (100), a layer of the first material (206) which was initially
5 interfacing with the first side of the external casing (202a, 202b) may melt away creating a void between the first side and the outermost layer of the first material (206). In this later stage of thermal runaway, smoke and other form of undesirable gases may be jetted out through the malfunctioning cell by blowing off of the metal cap or other venting mechanism internal to the cell. The porosity of the first 10 material (206) facilitates the diffusion of the undesirable gases and smoke towards the venting portion of the battery pack (100) which is the first side of the external casing (202a, 202b). The void earlier created now serves as a channel which allows the smoke and undesirable gases expelled from the malfunctioning cell and diffusing through the first material (206) to be guided to the external environment 15 through the channel created towards the one or more venting valves.
[00076] Additionally, the second material (208) covering the second pre-defined surface area of each cell of the plurality of cells (204) is a thermally conductive material which allows efficient heat radiation from inside the battery pack (100) to the external environment through the second side of the external casing (202a, 20 202b) comprising of a plurality of heat radiating units such as fins.
[00077] The coordinated operation of the first material (206) and the second material (208), together covering the entire surface area of each cell of the plurality of cells (204), provides an effective thermal management system for the battery pack (100). The first side of the external casing (202a, 202b) interfacing 25 with the first material (206) facilitates heat absorption, venting of smoke and undesirable gases and prevention of heat propagation while the second material (208) interfacing with the second side of the external casing (202a, 202b) facilitates heat transfer external to the battery pack (100).
[00078] The term “heat radiating units” used in accordance with the present disclosure refers to any extended surface which is configured to increase the rate of heat transfer to the external environment by way of conduction, convection and/or radiation.
[00079] Figure 4 illustrates a fire-resistant battery pack comprising of a first 5 material and a second material in accordance with some embodiments of the present disclosure.
[00080] Figure 4 illustrates a disposition of the first material (206) with reference to the second material (208) from a top perspective view to depict the configuration of the first material (206) and the second material (208) covering 10 the plurality of cells (204).
[00081] In an aspect, the first pre-defined surface area of the plurality of cells (204) is a range of 70% to 80% of surface area of each cell of the plurality of cells (204) is covered by the first material (206). In another aspect, the first pre-defined surface area of each cell is calculated with reference to the first side of the 15 external casing (202a, 202b).
[00082] In an embodiment, the first material (206) interfaces with at least the first side of the external casing (202a, 202b) which additionally serves as a venting portion of the battery pack (100).
[00083] In operation, the disclosed configuration of the first material (206) 20 facilitates the diffusion of gases generated internal to the battery pack (100) through the pores of the first material (206) and into the venting portion of the first side through which the undesirable gases are expelled into the external environment. For improved functionality of the battery pack (100) in venting of undesirable gases, the first pre-defined surface area is configured to interface with 25 and extend from a venting portion of the battery pack (100). The venting portion of the battery pack (100) refers to a side of the external casing (202a, 202b) comprising of one or more venting valves. In an embodiment, the first side of the
external casing (202a, 202b) is a surface of the top cover (202a) with a provision for venting valves. [00084] Additionally, the first material (206) comprises of heat absorption properties thereby restraining the propagation of heat from one point to another internal to the battery pack (100).
5
[00085] In an aspect, the first material (206) is composed of at least one of a polyurethane foam, latex rubber foam, high resilience foam, silicon and epoxy material or a combination thereof, to imbibe a thermally insulative property in the first material (206). In another embodiment, the first material (206) is a polyurethane foam. 10
[00086] In an aspect, the second pre-defined surface area of each cell of the plurality of cells (204) is in a range of 20% to 30% of the surface area of each cell of the plurality of cells (204) is covered by the second material (208). In another aspect, the second pre-defined surface area of each cell is calculated with reference to the second side of the external casing (202a, 202b). 15
[00087] In an embodiment, the second material (208) interfaces with at least a second side of the external casing (202a, 202b) of the battery pack (100). In another embodiment, the second side is disposed opposite to the first side of the external casing (202a, 202b). In another embodiment, the second side of the external casing (202a, 202b) being a side which has a plurality of fins and other 20 forms of heat radiating units.
[00088] In an embodiment, the second side of the external casing (202a, 202b) is a surface of the bottom cover (202b) of the external casing having a plurality of fins or other forms of heat radiating units.
[00089] In operation, the disclosed configuration facilitates effective thermal 25 management internal to the battery pack (100). In the event of thermal runaway occurring in the battery pack (100) there is development of tremendous heat and temperature internal to the battery pack (100). While the first side interfacing with the first material (206) facilitates venting by expelling undesirable gases from the
battery pack (100), the second side interfacing with the second material (208) helps in radiating heat external to the battery pack through the second material and then the second side comprising of a plurality of heat radiating units, mediums and devices. The second material (206) being a thermally conductive material effectively radiates the heat to the external environment.
5 [00090] Thereby in operation while the first side of the external casing (202a, 202b) interfacing with the first material (206) serves as a venting portion, the second side interfacing with the second material (208) serves as a heat radiating portion.
[00091] In an aspect, the second material (208) is composed of at least one of a 10 polyurethane foam, latex rubber foam, high resilience foam, silicon and epoxy material or a combination thereof to imbibe thermal conductivity property in the second material (208). In another embodiment, the second material (208) is composed of silicon.
[00092] Figure 5 illustrates a method for manufacturing a fire-resistant battery 15 pack in accordance with the embodiments of the present disclosure.
[00093] The method for manufacturing a fire-resistant battery pack starts at step 501 and then proceeds to 502.
[00094] At step 502, a plurality of cells (204) are disposed in an external casing (202a, 202b) of the battery pack (100). The external casing (202a, 202b) 20 comprises of a top cover (202a) and a bottom cover (202b). In an embodiment, the plurality of cells (204) are disposed on the bottom cover (202b) of the external casing (202a, 202b). In another embodiment, the plurality of cells are first disposed on the top cover (202a). For the purposes of ensuring prescribed cell spacing between the cells of the plurality of cells (204), the plurality of cells are 25 disposed in cell holders (212) and then disposed in the external casing (202a, 202b) thereby ensuring secure disposition. In an aspect, the plurality of cells (204) are disposed in a pre-defined pattern. In an embodiment, the pre-defined pattern is when the positive terminal of each cell of the plurality of cells (204) are disposed
on one side while all the negative terminals of each cell of the plurality of cell (204) are disposed on the other opposite side. For instance, all the negative terminal of the plurality of cells (204) are disposed on a side facing a surface of the bottom cover (202b) while all the positive terminals of the plurality of cells (204) face a surface of the top cover (202a). In another embodiment, the pre-5 defined pattern comprises of a combination of positive terminals and negative terminals of the plurality of cells (204) disposed on one side of the external casing (202a, 202b) while the remnant negative terminals and positive terminals face the other opposite side of the external casing (202a, 202b). The method (500) then proceeds to step (504).
10 [00095]
At step 504, a first material (206) is added into the external casing (202a, 202b) where the plurality of cells (204) are securely disposed with the help of cell holders (212). A first pre-defined volume of the first material (206) is added into the external casing (202a, 202b) so that the first material (206) can cover a first pre-defined surface area of each cell of the plurality of cells (204). In an aspect, 15 the first pre-defined surface area is 70% to 80% of the surface area of each cell of the plurality of cells (204) from a first side of the external casing (202a, 202b).
[00096] In an aspect, the first material (206) is added to the external casing (202a, 202b) such that the first material (206) interfaces with a surface of the external casing (202a, 202b) which is configured to act as a venting portion and comprises 20 of one or more venting valves. The first material (206) is a thermally insulative material. The method (500) then proceeds to step 506.
[00097] At step 506, the first material (206) is allowed to cure over a first pre-defined period of time. During the curing period, the first material (206) develops its porous texture which facilitates the diffusion of undesirable gases towards the 25 venting portion of the battery pack (100). During the curing period, the first material (206) is permitted to cover the first pre-defined surface area of the plurality of cells (204). In an aspect, the first pre-defined period of time for curing is at least 4 minutes and can extend beyond one hour based on the composition of
the first material (206) being used. After passage of the first pre-defined period of time, the method (500) proceeds to step 508. [00098] At step 508, a second material (208) is added into the
external casing (202a, 202b) comprising of the plurality of cells (204) and the first material (206). A second pre-defined volume of the second material (208) is added into the 5 external casing (202a, 202b) so that the second material (208) can cover a second pre-defined surface area of each cell of the plurality of cells (204). In an aspect, the second pre-defined surface area is 20% to 30% of the surface area of the each cell of the plurality of cells (204) from a second side of the external casing (202a, 202b). 10
[00099] In an aspect, the first side of the external casing (202a, 202b) is disposed opposite to the second side of the external casing (202a, 202b).
[000100] In an aspect, the second material (208) is added into the external casing (202a, 202b) such that one surface of the second material (208) interfaces with a surface of the first material (206) while another surface of the second 15 material (208) interfaces with a second side of the external casing (202a, 202b). The second side of the external casing (202a, 202b) comprises of a plurality of fins or other heat radiating units. The second material (208) is a thermally conductive material. The method (500) then proceeds to step 510.
[000101] At step 510, the second material (208) is allowed to cure over a 20 second pre-defined period of time. During the second pre-defined period of time, the second material (208) hardens to provide a sturdy and durable battery pack (100) which securely holds the plurality of cells (204) of the battery pack (100). In an aspect, the second pre-defined period of time for curing is at least 4 minutes and can extend beyond one hour based on the composition of the second material 25 (208) being used. After passage of the second pre-defined period of time, the method (500) proceeds to step 512.
[000102] At step 512, the battery pack (100) is enclosed by the external casing (202a, 202b) from an open surface, wherein the external casing (202a,
202b) comprises of the plurality of cells (204), the first material (206) and the second material (208). The open surface represents the surface from which the first material (206) and the second material (208) is added into the external casing (202a, 202b) comprising of the plurality of cells (204).
[000103]
In an embodiment, the second material (208) is first added into the 5 external casing (202a, 202b) comprising of the plurality of cells (204) wherein the plurality of cells (204) are securely disposed in cell holders (212). The second material (208) is then permitted to cure over a second pre-defined period of time after which the first material (206) is added into the external casing (202a, 202b). The first material (206) is then permitted to cure over a first pre-defined period of 10 time after which the battery pack (100) is enclosed from an open surface of the external casing (202a, 202b). The cell holder (212) is a very thin sheet configured to securely hold the plurality of cells (204) such that cell spacing and the pre-defined pattern of disposition is maintained. The thin layer of the cell holder (212) does not compromise the mechanical strength of the battery pack (100) as when 15 the second material (208) is added and allowed to cure, it hardens to provide the requisite mechanical support to the battery pack.
[000104] The terms “an embodiment”, “embodiment”, “embodiments”, “the embodiment”, “the embodiments”, “one or more embodiments”, “some embodiments”, and “one embodiment” mean “one or more (but not all) 20 embodiments of the invention(s)” unless expressly specified otherwise. The terms “including”, “comprising”, “having” and variations thereof mean “including but not limited to”, unless expressly specified otherwise. The terms “a”, “an” and “the” mean “one or more”, unless expressly specified otherwise.
[000105] The disclosed claimed limitations and the disclosure provided herein 25 provides a fire-resistant battery pack and a method of manufacture of the battery pack. The claimed invention in an aspect provides enhanced operational environmental safety by ascribing properties such as heat absorption, heat dissipation and prevention of fire between adjacent cells of the battery pack in accordance with the disclosure of the present subject matter. 30
[000106] In an aspect, the battery pack (100) comprising of the first material and the second material prevents the propagation of fire occurring in battery pack (100) to neighbouring components.
[000107] Under operational testing conditions, the fire-resistant battery pack (100) when exposed to a direct flame having a temperature of over 1200°C 5 prevents the propagation of fire external to the battery pack (100). The fire-resistant battery pack (100) in restricting the propagation of fire leads to confinement of fire mishaps which often lead to catastrophic failures. Thus, the disclosed subject matter promotes a safer environment for operation of systems employing battery packs. 10
[000108] Conventional battery packs carry a disclosure where they are strictly prohibited to be subjected to direct flames, which tremendously reduces the scope of application of conventional battery packs in high temperature operations. The present subject matter addresses this exact drawback of conventional battery packs by providing a fire-resistant battery pack capable of operation at higher 15 temperature ranges whilst ensuring a safe operational environment.
[000109] In an aspect, the occurrence of thermal runaway in batteries is a potential hazard that all manufacturers are to deal with and conventional battery packs are typically not equipped with inherent mechanisms to counter thermal runaway. The present subject matter discloses a battery pack (100) in accordance 20 with the present subject matter comprising of a first material (206) and a second material (208) which ensures effective thermal management in the battery pack (100). While the first material (208) absorbs heat and assists in effective venting in the battery pack (100), the second material (208) facilitates effective dissipation of heat in the battery pack (100). Thereby, the battery pack (100) in accordance 25 with the disclosed configuration addresses issues arising from occurrence of thermal runaways and improves the durability and life cycle of the battery pack (100).
[000110] In an aspect, the fire-resistant battery pack (100) comprising of the first material (206) and the second material (208) when used in a vehicle, adheres to 30 the Rechargeable Electrical Energy Storage System (REESS) against exposure to
fire from outside of the vehicle, warranting passengers of the vehicle enough time for evacuation from the vehicle in the event of fire.
[000111] In an aspect, the disclosed battery pack (100) comprising of the first material (206) and the second material (208) possesses high mechanical strength to absorb mechanical shocks and vibrations when the battery pack is subjected to 5 impact or vibrational loads. In an aspect, high mechanical strength of the battery pack (100) configures the battery pack (100) to be durable against operational wear and tear.
[000112] In light of the above-mentioned advantages and the technical advancements provided by the disclosed method of manufacture of the battery 10 pack and the fire-resistant battery pack, the claimed steps as discussed above are not routine, conventional, or well understood in the art, as the claimed steps enable the following solutions to the existing problems in conventional technologies. Further, the claimed steps clearly bring an improvement in the functioning of the battery pack itself as the claimed steps provide a technical 15 solution to a technical problem.
[000113] A description of an embodiment with several components in communication with another does not imply that all such components are required, On the contrary, a variety of optional components are described to illustrate the wide variety of possible embodiments of the invention, 20
[000114] Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter and is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, 25 the embodiments of the present invention are intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.
[000115] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration 30
and are not intended to be limiting, with the true scope and spirit being indicated by the following claims. [000116] A person with ordinary skills in the art will appreciate that the systems, modules, and sub-modules have been illustrated and explained to serve as examples and should not be considered limiting in any manner. It will be further 5 appreciated that the variants of the above disclosed system elements, modules, and other features and functions, or alternatives thereof, may be combined to create other different systems or applications.
[000117] While the present disclosure has been described with reference to certain embodiments, it will be understood by those skilled in the art that various 10 changes may be made and equivalents may be substituted without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from its scope. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed, but that the 15 present disclosure will include all embodiments falling within the scope of the appended claims. , Claims:We claim,
1. A battery pack (100), the battery pack (100) comprising:
a plurality of cells (204), wherein the plurality of cells (204) comprising a pre-defined pattern of disposition in the battery pack (100);
a first material (206), 5
wherein the first material (206) being configured to cover a first pre-defined surface area of each cell of the plurality of cells (204), and
wherein the first material (206) being a thermally insulative material; 10
and
an external casing (202a, 202b), the external casing (202a, 202b) being configured to enclose at least the plurality of cells (204) and the first material (206).
15
2. The battery pack (100) as claimed in claim 1, wherein the battery pack (100) comprises a second material (208),
wherein the second material (208) being configured to cover a second pre-defined surface area of the each cell of the plurality of cells (204); 20
wherein the second material (208) being a thermally conductive material; and
wherein the battery pack (100) comprising the plurality of cells (204), the first material (206) and the second material (208) being enclosed by the external casing (202a, 202b). 25
3. The battery pack (100) as claimed in claim 1, wherein the pre-defined pattern being:
a positive terminal of each cell of the plurality of cells (204) interfacing with a first side of a plurality of sides of the external casing (202a, 202b); and
a negative terminal of each cell of the plurality of cells (204) interfacing with a second side of the plurality of sides of the external 5 casing (202a, 202b),
wherein the second side being disposed opposite to the first side.
4. The battery pack (100) as claimed in claim 3, wherein the pre-defined 10 pattern of disposition of the plurality of cells (204) being achieved by single side welding.
5. The battery pack (100) as claimed in claim 3, wherein the second material (208) being configured to interface with at least the second side of the 15 external casing (202a, 202b), and wherein the second side having a plurality of fins.
6. The battery pack (100) as claimed in claim 3, wherein the first material (206) being configured to interface with at least the first side of the 20 external casing (202a, 202b),
wherein the first material (206) being porous such that in the event of thermal runaway occurring in the battery pack (100) the porosity of the first material (206) allows diffusing of undesirable gases released by one cellbattery pack (100). 25
7. The battery pack (100) as claimed in claim 6, wherein the venting portion of the battery pack (100) being a side of the plurality of sides of the external casing (202a, 202b) of the battery pack (100) disposed with one or more venting valves; and 30
wherein the one or more venting valves being configured to release the undesirable gases from the battery pack (100) to the external environment,
wherein the first side of the external casing (202a, 202b) being the venting portion. 5
8. The battery pack (100) as claimed in claim 1, wherein the first pre-defined surface area of each cell of the plurality of cells (104) being a range of 70% to 80% of surface area of each cell from the first side of the external casing (202a, 202b). 10
9. The battery pack (100) as claimed in claim 2, wherein second pre-defined surface area of each cell of the plurality of cells (204) being a range of 20% to 30% of surface area of each cell from the second side of the external casing (202a, 202b). 15
10. The battery pack (100) as claimed in claim 1, wherein at least one of the first material (206) and the second material (208) being composed of at least one of a polyurethane foam, latex rubber foam, high resilience foam, silicon and epoxy material or a combination thereof. 20
11. A method (500) for manufacturing a battery pack (100), the method (500) comprising steps of
disposing (502), a plurality of cells (204) in an external casing (202a, 202b) of the battery pack (100), 25
wherein the plurality of cells (204) being disposed on the external casing (202a, 202b) in a pre-defined pattern;
adding (504), a first material (206) into the external casing (202a, 202b) disposed with the plurality of cells (204),
wherein a first pre-defined volume of the first material (206) being added into the external casing (202a, 202b) to cover a first pre-defined surface area of the plurality of cells (204);
curing (506), the first material (206) in the external casing (202a, 202b) over a first pre-defined period of time; 5
adding (508), a second material (208) into the external casing (202a, 202b),
wherein a second pre-defined volume of the second material (208) being poured into the external casing (202a, 202b) to cover a second pre-defined surface area of the plurality of cells 10 (204);
curing (510), the second material (208) in the external casing (202a, 202b) over a second pre-defined period of time; and
enclosing (512), the external casing (202a, 202b) comprising of the plurality of cells (204), the first material (206) and the second material 15 (208) from an open surface.
12. The method (500) for manufacturing the battery pack (100) as claimed in claim 11, wherein the first material (206) being a thermally insulative material and the second material (208) being a thermally conductive 20 material.
13. The method (500) for manufacturing the battery pack (100) as claimed in claim 11, wherein a cell holder (212) being provided in the battery pack (100) to seat each cell of the plurality of cells (204) in the external casing 25 (202a, 202b) in the pre-defined pattern before the first material (206) being added to the external casing (202a, 202b).
14.The method (500) for manufacturing the battery pack (100) as claimed inclaim 11, wherein the first pre-defined period of time and the second pre-defined period of time being at least 4 minutes.
15.The method (500) for manufacturing the battery pack (100) as claimed in5 claim 11, wherein the first pre-defined volume of the first material (206)being associated with the first pre-defined surface area, wherein the firstpre-defined surface area being 70% to 80% of the surface area of each cellof the plurality of cells (204) from a first side of the external casing (202a,202b); and10
wherein the second pre-defined volume of the second material (208)being associated with the second pre-defined surface area, whereinthe second pre-defined surface area being 20% to 30% of the surface areaof the each cell of the plurality of cells (204) from a second side of theexternal casing (202a, 202b),15
wherein the first side being opposite to the second side of the external casing (202a, 202b).
Dated this: 2nd September, 2023.