Battery pack of a vehicle having a thermal runaway detector

Abstract

The present invention is directed towards a battery pack (100) comprising a casing (102) accommodating one or more battery cells (104) within an interior portion (110) thereof, the casing (102) comprising a first visible part (106); and a color change material (108) located within the casing (102) so as to overlap at least partly with the first visible part (106) when viewed from a portion external to the casing (102), the color change material (108) being adapted to undergo a color change in response to coming in contact with at least one gas emitted by the one or more battery cells (104) before occurrence of battery thermal runaway situation. The battery pack (100) can be accommodated in a vehicle (10).

Description

“BATTERY PACK OF A VEHICLE HAVING A THERMAL RUNAWAY DETECTOR”Field of the Invention:

[0001] The invention relates to a battery pack having a thermal runaway situation detector. The invention furthermore relates to a vehicle comprising a battery packing having the thermal runaway situation detector.Background of the Invention:

[0002] A battery pack generally comprises a compartment housing one or more battery cells and control circuit for managing operation of the battery pack. The battery cells can be made of lithium- ion battery cells. Stressed lithium-ion (Li-ion) battery cells can undergo failure through a variety of factors. Failure of lithium-ion (Li-ion) battery cells can result in internal reactions that generate heat and chemical decomposition of the battery cell. When this occurs, the cell may vent flammable gases. Under certain conditions, these gases can ignite and spread to other cells within the battery pack, causing a battery thermal event known as thermal runaway.

[0003] It is desirable to monitor battery health to anticipate or detect thermal runaway accompanying battery failure. Early detection is helpful because a thermal runaway event can lead to a battery fire or explosion. In automotive applications, early detection and alerting of signs of battery failure or thermal runaway can help allow a passenger to timely exit a vehicle to ensure their safety.

[0004] Currently, available vehicle battery thermal runaway early warning system, take into account one or more of temperature of the battery, voltage output of the battery, presence of battery fault condition, presence of circuit fault, for detecting battery thermal runaway condition. However, the currently available vehicle battery thermal runaway early warning system are complicated and do not provide a reliable warning about the battery thermal runaway condition. Moreover, the currently available systems are relatively expensive, which increases the overall cost of the vehicle.

[0005] Thus, there exists a need to provide a vehicle battery thermal runaway early warning system that addresses one or more of the aforesaid disadvantages.Summary of the Invention:

[0006] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0007] Accordingly, the present invention provides a battery pack comprising a casing accommodating one or more battery cells within an interior portion thereof, the casing comprising a first visible part; and a color change material located within the casing so as to overlap at least partly with the first visible part when viewed from a portion external to the casing, the color change material being adapted to undergo a color change in response to coming in contact with at least one gas emitted by the one or more battery cells before occurrence of battery thermal runaway situation.

[0008] In an embodiment of the invention, the interior portion of the casing comprises at least one holder structure in close proximity of the first visible part for receiving the at least one color change material.

[0009] In another embodiment of the invention, the at least one holder structure comprises a housing for accommodating the at least one color change material, the housing comprising at least one aperture for the at least one gas emitted by the one or more battery cells to pass therethrough and come in contact with the at least one color change material.

[0010] In yet another embodiment of the invention, the housing comprises a second visible part that overlaps at least partly with the first visible part when viewed from a portion external to the casing.

[0011] In still another embodiment of the invention, the casing comprises an optical sensor located in close proximity of the color change material and adapted to generate a color indicative signal indicative of a color of the color change material; a processing circuit electrically coupled to the optical sensor and receiving the color indicative signal from the optical sensor, the processing circuit being adapted to detect a change of color of the color change material and generating analarm signal in response thereto; and at least one of an alarm device and a transmitting device electrically coupled to the processing circuit, the alarm device receiving the alarm signal from the processing circuit and providing an alarm output; the transmitting device receiving the alarm signal from the processing circuit and transmitting the alarm signal to a remote receiving unit.

[0012] In a further embodiment of the invention, the color change material being selected from a group comprising: Copper Oxide; Iron; Silica Oxide (Quartz); Hydrogen peroxide; Zinc Oxide and Nickel Oxide.

[0013] In a furthermore embodiment of the invention, the copper oxide is copper (II) oxide (CuO); the iron is iron (Fe); the silica oxide is silicon dioxide (SiO2); the hydrogen peroxide is H2O2; the zinc oxide is ZnO; and the nickel oxide is NiO.

[0014] Additionally, the present invention provides a vehicle comprising: a battery pack providing an early indication of occurrence of battery thermal runaway situation, said battery pack comprising: a casing accommodating one or more battery cells within an interior portion thereof, the casing comprising a first visible part; and a color change material located within the casing so as to overlap at least partly with the first visible part when viewed from a portion external to the casing, the color change material being adapted to undergo a color change in response to coming in contact with at least one gas emitted by the one or more battery cells before occurrence of battery thermal runaway situation.

[0015] An advantage of the invention is that the present invention provides an early detection of battery thermal runaway situation, even before the same occurs. Another advantage of the invention is that the detection of battery thermal runaway situation as per the present invention is based on the aspect that before a thermal runaway situation occurs in a Lithium-ion battery pack, various gases are be emitted due to the breakdown of the electrolyte and other materials within the battery. These gases typically include:1. Carbon Dioxide (CO2): Released due to the decomposition of organic solvents in the electrolyte.2. Carbon Monoxide (CO): Atoxic gas that can be produced from the decomposition of the electrolyte or other organic materials in the battery.3. Hydrogen (H2): Generated from the breakdown of water or other hydrogen-containing compounds in the electrolyte.4. Methane (CH4): Formed as a result of the breakdown of electrolyte solvents.5. Ethylene (C2H4) and Ethane (C2H6): Hydrocarbon gases that can be released from the degradation of the electrolyte.6. Hydrogen Fluoride (HF): A highly toxic and corrosive gas that can be produced if the electrolyte contains lithium hexafluorophosphate (LiPFe), a common electrolyte salt.

[0016] Out of the aforesaid gases which are emitted by the battery pack, detection of methane provides a highly accurate and substantially early indication battery thermal runaway situation. Thus, the color change material which is used in the present invention is adapted to sense methane which is emitted by the battery pack prior to occurrence of the battery thermal runaway situation.

[0017] Another advantage of the invention is that the battery pack is constructed so as to allow for visual detection of thermal runaway situation. Thus, in case the battery pack is readily visible in the vehicle or in case the battery pack is of a replaceable type (i.e. a battery pack which can be removed from the vehicle when the charge is depleted and is replaced with another charged battery pack), the battery pack allow for ease visual detection of thermal runaway situation.

[0018] Yet another advantage of the invention is that the battery pack comprises an optical sensor located in close proximity of the color change material and adapted to generate a color indicative signal indicative of a color of the color change material, a processing circuit being adapted to detect a change of color of the color change material and generating an alarm signal in response thereto and an alarm device providing an alarm output, which will be useful in case the battery pack is not readily visible in the vehicle.

[0019] Still another advantage of the invention is that the battery pack comprises an optical sensor located in close proximity of the color change material and adapted to generate a color indicative signal indicative of a color of the color change material, a processing circuit being adapted to detect a change of color of the color change material and generating an alarm signal in response thereto and a transmitting device for transmitting the alarm signal to a remote receiving unit. Thus, a user need not be in close proximity of the battery to detect the thermal runaway situation.

[0020] A further advantage of the invention is that the choice of the color change material as per the present invention are such that each color change material undergoes fast color change (i.e. within a very short period of time) upon coming contact with the least one gas emitted by the one or more battery cells. Thus, a response time is very short.

[0021] A furthermore advantage of the invention is that the color change is such that it can be easily detected. For instance, Copper (II) oxide (CuO) which is black in color turns into reddish- brown color upon coming in contact with methane gas, which is easily detectable. By way of another example, if the color change material is Iron (Fe) which is silver grey in color turns into dark grey upon coming in contact with methane gas, which is once again easily detectable. By way of yet another example, if the color change material is Silica oxide (SiCh), a white powder, turns into reddish powder upon coming in contact with methane gas, which is once again easily detectable. By way of a further more example, if the color change material is Hydrogen Peroxide (H2O2) which is blue in color turns colorless upon coming in contact with methane gas, which is once again easily detectable. By way of another example, if the color change material is Zinc Oxide (ZnO) which is blue powder turns colorless upon coming in contact with methane gas, which is yet again easily detectable. By way of one more example, if the color change material is Nickel Oxide (NiO) which is green in color turns silvery white upon coming in contact with methane gas, which is easily detectable.

[0022] Another advantage of the invention is that the color change materials used are commonly or readily available. Also, the cost of the color change materials is substantially low. Thus, the cost of the battery pack is not substantially increased.

[0023] To further clarify the advantages and features of the invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.BRIEF DESCRIPTION OF THE FIGURES:

[0024] In order that the invention may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying drawings, where like reference numerals refer to identical or functionally similar elements throughout the separate views. The figures together with a detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present invention where:

[0025] Figure 1 illustrates a side view of a vehicle, in accordance with an embodiment of the present invention;

[0026] Figure 2 illustrates a perspective semi-transparent view of a battery pack, in accordance with an embodiment of the present invention; and

[0027] Figure 3 illustrates a perspective semi-transparent view of the battery pack in accordance with another embodiment of the present invention;

[0028] It may be noted that to the extent possible, like reference numerals have been used to represent like elements in the drawings. Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily been drawn to scale. For example, the dimensions of some of the elements in the drawings may be exaggerated relative to other elements to help to improve understanding of aspects of the present invention. Furthermore, one or more elements may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.Detailed Description of the Invention:

[0029] For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device,and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

[0030] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the invention and are not intended to be restrictive thereof.

[0031] As used in the description herein and throughout the claims that follow, the meaning of “a,”, “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

[0032] Reference throughout this specification to “an aspect”, “another aspect” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase “in an embodiment”, “in another embodiment”, and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0033] The terms "comprises", "comprising", or any other variations thereof, are intended to cover anon-exclusive inclusion, such that one or more devices or sub-systems or elements or structures or components proceeded by "comprises... a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

[0034] As used herein, and unless the context dictates otherwise, the terms "coupled to", “connected to”, “operably connected to”, and “operatively connected to” are intended to include both direct connection / coupling (in which two elements that are coupled / connected to each other contact each other) and indirect coupling / connection (in which at least one additional element is located between the two elements). Therefore, the terms "coupled to" and "coupled with" are used synonymously. Similarly, the terms “connected to” and “connected with” are used synonymously.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one ordinary skilled in the art to which this invention belongs. The device, methods, and examples provided herein are illustrative only and not intended to be limiting.

[0036] The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention. No language in the specification should be construed as indicating any non-mentioned element as being essential to the practice of the invention.

[0037] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used.

[0038] While the present invention is illustrated in the context of a vehicle, however, cover and aspects and features thereof can be used with other types of vehicles as well. The terms “vehicle”, “two wheeled vehicle” and “motorcycle” have been interchangeably used throughout the description. The term “vehicle” comprises vehicles such as motorcycles, scooters, bicycles, mopeds, scooter type vehicles, All-Terrain Vehicles (ATV) and the like.

[0039] The terms “front / forward”, “rear / rearward / back / backward”, “up / upper / top”, “down / lower / lower ward / downward, bottom”, “left / leftward”, “right / rightward” used therein represents the directions as seen from a vehicle driver sitting astride and these directions are referred by arrows Fr, Rr, Ur, Lr, L, R in the Figures.

[0040] Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

[0041] Referring to Figure 1, there is illustrated a first side view of a vehicle (10). The vehicle (10) comprises, inter-alia, a front fork (12), a front ground engaging member (14), a front fender (16), a headlight (18), a rear ground engaging member (20), a steering handle bar (22), a power unit (24), a seat (26), a tail light (28), a rear cushion (30), a rear fender (32), a transmission unit (34) and a frame structure (36).

[0042] The vehicle (10) further comprises at least one battery pack (100) for providing power to the power unit (24) which may be a motor unit. Alternatively, the at least one battery pack may provide electrical energy to one or more electrical / electronic component provided in the vehicle and the power unit may be a conventional IC engine. Further, the transmission unit (34) transfers the motion generated by the power unit (24) to the rear ground engaging member (20). In an embodiment of the invention, the at least one battery pack (100) is supported by the frame structure (36). The battery may be fixed removable battery.

[0043] It may be noted that the vehicle (10) is shown to have included above stated parts, however, those skilled in the art would appreciate that the vehicle (10) includes other parts which may not be relevant for explaining the present invention and hence are not shown and described.

[0044] Now referring to Figure 2, there is illustrated a semi-transparent perspective view of a battery pack (100) in accordance with a first embodiment of the invention. The battery pack (100) comprises a casing (102) accommodating one or more battery cells (104) within an interior portion (110) thereof. The casing (102) further comprises a first visible part (106). The battery pack (100) further comprises a color change material (108) located within the casing (102). The color change material (108) is positioned so as to overlap at least partly with the first visible part (106) when viewed from a portion external to the casing (102). The color change material (108) is adapted to undergo a color change in response to coming in contact with at least one gas emitted by the one or more battery cells (104) before occurrence of battery thermal runaway situation.

[0045] In an embodiment of the invention, the interior portion (110) of the casing (102) comprises at least one holder structure (112) in close proximity of the first visible part (106) for receiving the at least one color change material (108). In an embodiment of the invention, the at least one holder structure (112) comprises a housing (114) for accommodating the at least one color changematerial (108), the housing (114) comprising at least one aperture (116) for the at least one gas emitted by the one or more battery cells (104) to pass therethrough and come in contact with the at least one color change material (108). In an embodiment of the invention the housing (114) comprises a second visible part (118) that overlaps at least partly with the first visible part (106) when viewed from a portion external to the casing (102). The holder structure (112) is positioned close to the top portion of casing (102). Top end is physically top portion of the battery.

[0046] To ensure effective interaction with gas flow, the holder structure (112) should be positioned at the gas path's accumulation location. Placing it at the top can take advantage where rising gases in one or more battery cells (104) enter from the aperture (116) provided in the housing (114) and come in contact with the color change material (108). Such positioning of the holder structure (112) ensures efficient monitoring, collection, or reaction processes. This positioning enhances performance, whether for sensing, filtering, or other functions, while ensuring safety and ease of maintenance.

[0047] Now referring to Figure 3, there is illustrated a semi-transparent perspective view of a battery pack (100) in accordance with a first embodiment of the invention. The battery pack (100) comprises the elements as described above in relation to Figure 2 above. Additionally, the casing (102) of the battery pack (100) comprises an optical sensor (120) located in close proximity of the color change material (108) and adapted to generate a color indicative signal indicative of a color of the color change material (108). The casing (102) of the battery pack (100) further comprises a processing circuit (122) electrically coupled to the optical sensor (120). The processing circuit (122) receives the color indicative signal from the optical sensor (120). The processing circuit (122) detects a change of color of the color change material (108) and generates an alarm signal in response thereto. The casing (102) of the battery pack (100) further comprises at least one alarm device (124). The at least one alarm device (124) receives the alarm signal from the processing circuit (122) and provides an alarm output. The alarm device (124) may provide an audio output or a visual output. For instance, the alarm device (124) may be a speaker to provide an audio output. Alternatively, the alarm device (124) may be a lighting device to provide a visual output. The casing (102) of the battery pack (100) may alternatively or additionally comprise a transmitting device (126) electrically coupled to the processing circuit (122). The transmittingdevice (126) receives the alarm signal from the processing circuit (122) and transmits the alarm signal to a remote receiving unit (128).

[0048] The color change material (108) as present within the casing (102) as per the first embodiment and as per the second embodiment is selected from a group comprising: Osmium, Copper Oxide; Iron; Silica Oxide (Quartz); Hydrogen peroxide; Zinc Oxide and Nickel Oxide.

[0049] By way of a non-limiting example, the osmium is osmium complex, copper oxide is copper (II) oxide (CuO); the iron is iron (Fe); the silica oxide is silicon dioxide (SiO2); the hydrogen peroxide is H2O2; the zinc oxide is ZnO; and the nickel oxide is NiO. Preferably, the color change material (108) as present within the casing (102) as per the first embodiment and as per the second embodiment is osmium, and more preferably, an osmium complex.

[0050] In one embodiment of the invention, the first visible part (106) is made of transparent or semi-transparent material selected from a group comprising: plastic glass, metallic or plastic mesh.

[0051] One advantage of the present invention is that it enables the early detection of a battery thermal runaway situation, even before it fully occurs. Another benefit is that the detection method is based on the observation that, before thermal runaway happens in a Lithium-ion battery pack, various gases are emitted due to the breakdown of the electrolyte and other materials within the battery. These gases typically include:1. Carbon Dioxide (CO2): Released from the decomposition of organic solvents in the electrolyte.2. Carbon Monoxide (CO) : A toxic gas produced from the breakdown of the electrolyte or other organic materials in the battery.3. Hydrogen (H2): Generated from the decomposition of water or other hydrogen-containing compounds in the electrolyte.4. Methane (CHi): Formed as a result of the breakdown of electrolyte solvents.5. Ethylene (C2H4) and Ethane (C2H6): Hydrocarbon gases released due to electrolyte degradation.6. Hydrogen Fluoride (HF): A highly toxic and corrosive gas that can be produced if the electrolyte contains lithium hexafluorophosphate (LiPFe), a common electrolyte salt.

[0052] Methane detection offers an early and accurate warning of impending battery thermal runaway, a critical failure mode distinct from normal heating or cell leakage. While normal heating is manageable and leakage involves localized issues, thermal runaway is a rapid, uncontrollable temperature rise caused by factors like short circuits or overcharging, often leading to fires or explosions. During early electrolyte decomposition, the emission of methane serves as a key indicator. The color-change material used in this invention is specifically designed to detect emission of methane before thermal runaway, enabling timely preventive measures to enhance safety.

[0053] Thermal runaway happens when a battery overheats uncontrollably, often triggered by specific issues. Overcharging can push too much energy into the battery, causing it to overheat. Over-discharging can damage the battery's structure, leading to internal short circuits. Leakage, caused by damage or defects, can expose battery materials to air or other reactive substances, creating heat. Once it begins, the heat builds up rapidly, making the situation worse and potentially leading to fire or explosion.

[0054] If thermal runaway is detected, the vehicle can gradually reduce motor RPM to lower battery stress and heat generation while maintaining safe control for the driver. Simultaneously, cooling systems can activate to dissipate heat, such as increasing airflow, directing coolant to overheated cells. These measures help slow the escalation, mitigate risks, and provide time for passengers to exit safely.

[0055] Another advantage of the invention is that the battery pack is designed to enable visual detection of a thermal runaway situation. This feature is particularly beneficial when the battery pack is easily visible within the vehicle or when it is of a replaceable type — meaning it can be removed and swapped with a charged battery when the current one is depleted. In such cases, the design allows for easy visual identification of a thermal runaway situation.

[0056] Another advantage of the invention is that the battery pack includes an optical sensor positioned near the color-change material. This sensor is designed to generate a signal indicating the color of the material. A processing circuit detects any color change and, in response, triggersan alarm signal. An alarm device then provides an alert, which is especially useful when the battery pack is not easily visible within the vehicle.

[0057] Another advantage of the invention is that the battery pack is equipped with an optical sensor placed near the color-change material, which generates a signal indicating the material’s color. A processing circuit detects any color changes and triggers an alarm signal in response. Additionally, a transmitting device sends the alarm signal to a remote receiving unit, allowing the user to detect a thermal runaway situation without needing to be near the battery.

[0058] An additional advantage of the invention is that the selected color-change materials are designed to undergo a rapid color shift (i.e., within a very short time) when exposed to at least one of the gases emitted by the battery cells. As a result, the response time is significantly reduced.

[0059] Another advantage of the invention is that the color change of the material is designed for easy detection. For example, Copper (II) oxide (CuO), which is black, turns reddish-brown when exposed to methane, making it easily identifiable. Similarly, the Iron (Fe), which is silver-grey, changes to dark grey upon contact with methane. Silica oxide (SiCh), a white powder, turns reddish when it reacts with methane, also making it noticeable. Hydrogen Peroxide (H2O2), initially blue, becomes colorless upon exposure to methane, while Zinc Oxide (ZnO), a blue powder, also turns colorless. Finally, Nickel Oxide (NiO), green in color, changes to silvery white when it interacts with methane, providing another easily detectable sign. The osmium complex depending upon the nature of the complex thus formed undergoes color change.

[0060] Another advantage of the invention is that the color change materials used are commonly or readily available. Also, the cost of the color change materials is substantially low. Thus, the cost of the battery pack is not substantially increased.

[0061] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.

[0062] The figures and the forgoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.

Claims

CLAIM:

1. A battery pack (100) comprising: a casing (102) accommodating one or more battery cells (104) within an interior portion (110) thereof, the casing (102) comprising a first visible part (106); and a color change material (108) located within the casing (102) so as to overlap at least partly with the first visible part (106) when viewed from a portion external to the casing (102), the color change material (108) being adapted to undergo a color change in response to coming in contact with at least one gas emitted by the one or more battery cells (104) before occurrence of battery thermal runaway situation.

2. The battery pack (100) as claimed in claim 1, wherein the interior portion (110) of the casing (102) comprises at least one holder structure (112) in close proximity of the first visible part (106) for receiving the at least one color change material (108).

3. The battery pack (100) as claimed in claim 2, wherein the at least one holder structure (112) comprises a housing (114) for accommodating the at least one color change material (108), the housing (114) comprising at least one aperture (116) for the at least one gas emitted by the one or more battery cells (104) to pass therethrough and come in contact with the at least one color change material (108).

4. The battery pack (100) as claimed in claim 3, wherein the housing (114) comprises a second visible part (118) that overlaps at least partly with the first visible part (106) when viewed from a portion external to the casing (102).

5. The battery pack (100) as claimed in claim 1, wherein the casing (102) comprises: an optical sensor (120) located in close proximity of the color change material (108) and adapted to generate a color indicative signal indicative of a color of the color change material (108); a processing circuit (122) electrically coupled to the optical sensor (120) and receiving the color indicative signal from the optical sensor (120), the processing circuit (122) being adapted to detect a change of color of the color change material (108) and generating an alarm signal in response thereto; and at least one of an alarm device (124) and a transmitting device (126) electrically coupled to the processing circuit (122), the alarm device (124) receiving the alarm signal from the processing circuit (122) and providing an alarm output; the transmitting device(126) receiving the alarm signal from the processing circuit (122) and transmitting the alarm signal to a remote receiving unit (128).

6. The battery pack (100) as claimed in claim 1, wherein the color change material (108) being selected from a group comprising: Osmium, Copper Oxide, Iron Oxide, Silica Oxide (Quartz), Hydrogen peroxide, Zinc Oxide; and Nickel Oxide.

7. The battery pack (100) as claimed in claim 6, wherein the osmium is an osmium complex, Copper Oxide is Copper (II) oxide (CuO); the iron is iron (Fe); the silica oxide is silicon dioxide (SiO?); the hydrogen peroxide is H2O2; the zinc oxide is ZnO; and the nickel oxide is NiO.

8. A vehicle (10) comprising: a battery pack (100) providing an early indication of occurrence of battery thermal runaway situation, said battery pack (100) comprising: a casing (102) accommodating one or more battery cells (104) within an interior portion (110) thereof, the casing (102) comprising a first visible part (106); and a color change material (108) located within the casing (102) so as to overlap at least partly with the first visible part (106) when viewed from a portion external to the casing (102), the color change material (108) being adapted to undergo a color change in response to coming in contact with at least one gas emitted by the one or more battery cells (104) before occurrence of battery thermal runaway situation.

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