Description:

SYSTEM AND METHOD FOR PREVENTION OF THERMAL PROPAGATION IN BATTERY PACK

TECHNICAL FIELD
[0001] The present invention generally relates to a battery pack, and more particularly to a system and method for prevention of thermal propagation in battery pack.

BACKGROUND
[0002] Battery pack is one of most important components of many modern electronic devices and specifically of electric vehicles, representing a remarkable technological leap towards energy-efficient, portable, and sustainable solutions. The battery pack consists of individual cells which, when ingeniously combined in specific series and parallel configurations, culminate in a single high-energy-density unit. Such a configuration promises extended device run-times and longer driving ranges for electric vehicles. However, such impressive energy density also presents engineers and manufacturers with significant challenges, primarily when it comes to heat management.
[0003] The intricate design of a battery pack, characterized by its tight arrangement of cells, often complicates thermal dissipation. In simpler terms, the more closely these energy-rich cells are packed together, the harder it becomes to manage their combined heat output. The internal architecture and chemistry of these cells make them susceptible to a phenomenon known as 'thermal runaway'. Thermal runaway event isn't just a mere overheating of the battery but represents a far more volatile reaction.
[0004] Thermal runaway can be visualized as a domino effect of escalating temperatures within a battery cell. Thermal runaway often begins with a singular cell experiencing a rapid and uncontrolled temperature rise. The heat surge is usually accompanied by the release of a flammable gas, a byproduct of the internal reactions within the cell. If the gas isn't dissipated swiftly or remains trapped within the battery pack, it can cause an increase in the temperatures of adjacent cells. The rapid heating of one cell can thus trigger a chain reaction, leading to rapidly heat up, which can then spread to adjacent cells, potentially leading to a catastrophic failure of the entire battery pack. Without adequate safeguards like thermal insulation, cooling systems, cell spacing, venting, and safety mechanisms, this phenomenon (e.g., thermal propagation) can lead to catastrophic failures like fires or explosions. In a battery pack filled with closely packed cylindrical cells, the thermal propagation can be especially swift and dangerous. Additionally, given the nature of the gases released and the high temperatures achieved, the battery pack can become an explosive hazard, jeopardizing the safety of users and their surroundings.
[0005] In contemporary battery designs, manufacturers have employed various strategies to mitigate the risk of thermal runaway, which often results in thermal propagation. Many of these strategies hinge on the principle of structural integrity. By designing battery packs that can withstand certain pressure levels and by setting up mechanisms to maintain temperatures below specific thresholds, the risk of runaway reactions can be curbed. Furthermore, modern battery packs often incorporate thermal cutoffs—safety mechanisms that disrupt the battery's operation once temperatures approach dangerous levels. On paper, and under ideal conditions, these measures appear sufficient.
[0006] However, the real-world application of battery packs is far from ideal. Over time, multiple factors, including regular wear and tear, can compromise the battery's internal structure. Cell degradation, which is an inevitable part of a battery's lifecycle, can further exacerbate the risk of thermal runaway. Additionally, unforeseen issues like internal shorts can introduce more unpredictability into the mix. When these factors converge, even the most robustly designed battery packs can fall prey to thermal runaway.
[0007] In essence, while current battery pack designs have undoubtedly advanced in terms of energy density and initial safety measures, they remain vulnerable to the relentless and unpredictable nature of thermal reactions. Achieving a balance between high energy density and safety remains an intricate dance—one where even a minor misstep can lead to catastrophic results. As the demand for powerful and reliable battery packs continues to grow in today's energy-conscious world, the pressing challenge for innovators lies in devising designs that can consistently keep the menace of thermal propagation at bay.

SUMMARY
[0008] The aim of the present disclosure is to provide a battery pack and a method for assembling the battery pack to mitigate or eliminate thermal propagation in the battery pack when thermal runaway occurs in at least one cell of a plurality of cells of the battery pack. The battery pack is assembled by stacking multiple materials between the plurality of cells to eliminate thermal propagation between each of the cells.
[0009] The present disclosure relates to a battery pack. The battery pack comprises a housing; a plurality of cells placed inside the housing, wherein the plurality of cells are spaced apart from each other by a predefined gap; a foam layer disposed inside the housing up to a first predetermined level of a cell height; a thermal interface material (TIM) disposed at a top surface and a bottom surface of the foam layer, wherein the TIM extends up to a second predetermined level of the cell height; a first separator separates the TIM and the top surface of the foam layer; and a second separator separates the TIM and the bottom surface of the foam layer.
[0010] In an embodiment, the foam layer comprises one of: a polyurethane foam, a polyethylene foam, a rubber foam, a silicone foam, a polyvinyl chloride foam or a combination thereof.
[0011] In an embodiment, the first separator or the second separator comprises one of: a natural rubber, a silicon rubber, a ceramic composite, a polyethylene oxide, a glass fiber , a silica glass, a polyethylene, a polypropylene, a polyethylene terephthalate, a polyvinyl chloride, a polyacrylate or a combination thereof.
[0012] In an embodiment, the TIM comprises one of a phase change material (PCM) and a potting material.
[0013] In another embodiment, the potting material includes at least one of an epoxy, a silicone, and a urethane.
[0014] In an embodiment, the phase change material (PCM) includes at least one of organic PCMs, inorganic PCMs, and eutectic PCMs.
[0015] In another embodiment, the TIM is in physical contact with a plurality of cells of the battery pack.
[0016] In an embodiment, the first predetermined level is 10% to 70% and the second predetermined level is 16 % to 86 %.
[0017] In an embodiment, the first separator separates the TIM and the foam layer with a distance of 2 % to 10 % of the cell height and the second separator separates the TIM and the foam layer with the distance of 2% to 10 % of the cell height.
[0018] In an embodiment, the TIM extends, towards an upward direction from the top surface of the foam layer, up to a third predetermined level of the cell height.
[0019] In yet another embodiment, the TIM extends, towards a downward direction from the bottom surface, up to a fourth predetermined level of the cell height.
[0020] In an embodiment, the third predetermined level is 16 % to 86 % and the fourth predetermined level is 16 % to 86 %.
[0021] The present disclosure relates to a method for assembling a battery pack, the method comprising: receiving, a plurality of cells inside a housing, wherein the plurality of cells are spaced apart from each other by a predefined gap; providing a foam layer inside the housing up to a first predetermined level of a cell height; applying a thermal interface material (TIM) at a top surface and a bottom surface of the foam layer, wherein the TIM extends up to a second predetermined level of the cell height; disposing a first separator to separate the TIM and the top surface of the foam layer; and disposing a second separator separate the TIM and the bottom surface of the foam layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein.
[0023] Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams.
[0024] FIG. 1 illustrates a battery pack, in accordance with embodiments of the present disclosure;
[0025] FIG. 2 illustrates a method for assembling a battery pack, in accordance with embodiments of the present disclosure;
[0026] FIG. 3 showcases a top view of a battery pack, in accordance with embodiments of the present disclosure;
[0027] FIG. 4 presents a front view of a battery pack in accordance with embodiments of the present disclosure; and
[0028] FIG. 5 illustrates an exploded view of a battery pack, in accordance with embodiments of the present disclosure;

DETAILED DESCRIPTION OF EMBODIMENTS
[0029] The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.
[0030] FIG. 1 illustrates a battery pack 100, in accordance with an embodiment of the present disclosure. The battery pack 100 comprises a housing 102, a plurality of cells 104-A1, 104-A2, .....,104-AN, a foam layer 106, a thermal interface material (TIM) 108, a first separator 110 and a second separator 112.
[0031] In an embodiment, the battery pack 100 seeks to prioritize both performance and safety. The battery pack 100 is designed, integrating multiple components to ensure optimum energy distribution while minimizing risks associated with overheating, such as thermal runaway. The battery pack 100 comprises the housing 102 that acts as the first line of defense against external environmental factors, ensuring the internal components remain shielded from potential harm.
[0032] In an embodiment, the housing 102 of the battery pack 100 encapsulates and safeguards the internal elements. Housing 102 is constructed using durable materials chosen for their robustness and resistance to external adversities. The design of housing 102 is engineered to withstand challenging environmental conditions, such as extreme temperatures, humidity, and even mechanical stresses. Furthermore, beyond mere protection, the housing 102 plays a critical role in thermal management. The material and architecture of housing 102 are optimized to aid in dissipating heat generated within the battery pack 100, thereby acting as an additional layer in preventing overheating. The structural integrity of housing 102 ensures that the internal components, especially the cells 104-A, remain isolated from external influences, reducing risks associated with potential damage. Simultaneously, the design of housing 102 facilitates easy integration into devices or vehicles, demonstrating a blend of functionality and adaptability.
[0033] Inside the housing 102 lies the plurality of cells 104-A1, 104-A2, 104-A3….104-AN (hereinafter collectively or individually referred as cells 104-A or cell 104-A), which collectively provide the energy necessary to power various devices or electric vehicles. The cells 104-A are placed inside the housing 102, wherein each cell 104-A is spaced apart from the cells 104-A in vicinity by a predefined gap. By maintaining the predefined gap, the design ensures that heat generated from a cell 104-A has a reduced chance of excessively influencing the temperature of the cells 104-A in vicinity, thereby helping in reducing the risk of thermal propagation. The distance can be in the range of 3 to 15 mm. The distance between cells 104-A depends on total number of cells 104-A, capacity of cells 104-A, overall capacity of battery pack and the like.
[0034] In an embodiment, surrounding the cells 104-A and spanning the interior of the housing 102 is the foam layer 106 that extends longitudinally inside the housing 102 up to a first predetermined level of the height of the cell 104-A (interchangeably referred to as a cell height). Such strategic positioning of foam layer 106 ensures that a substantial part of the cell 104-A remains in contact with the foam. The foam layer 106 provides insulation between cells 104-A and structural integrity to the battery pack. Depending on the specific requirements, the foam layer 106 could be made of materials like polyurethane foam, polyethylene foam, rubber foam, silicone foam, polyvinyl chloride foam, or even a synergistic combination of these materials. Each of these foams offers distinct properties, with some providing better heat management while others offer improved resistance to chemical reactions. The foam layer 106 acts as a thermal insulator, reducing heat transfer between adjacent cells 104-A. This ensures that a malfunction or overheating in one cell 104-A doesn't adversely affect neighboring cells 104-A, thereby enhancing the overall safety of the battery pack. Further, foam layer 106 also provides a cushioning effect, absorbing vibrations and shocks. Furthermore, foam layer 106 provides a physical barrier between cells 104-A to prevent electrical shorts or unintended contacts, especially if a casing of cell 104-A is damaged. The foam layer 106 is disposed inside housing 102 in a manner such that foam layer 106 covers the portion of the entire vertical dimension of the cells 104-A i.e. and up to a certain height of the vertical dimension. Such disposal of foam layer 106 ensures that the cells 104-A (often the central regions) can benefit from the protective and insulative effects of foam layer 106 without increasing the overall size or weight of the battery pack. As the form layer 106 covers only a portion (i.e., first predetermined level of cell height) of the cell 104-A to allow more direct cooling of the uncovered parts of the cells 104-A, which could be beneficial if there's active cooling in the battery pack or if passive cooling (through natural convection). Further, partial covering of cells 104-A (through foam layer 106) prevents accumulation of heat and possible damage to the battery pack and reduces material consumption. The term "cell height" refers to a vertical measurement or distance from the base (bottom) to the top of a battery cell. In prismatic or pouch cells, which are generally rectangular, the cell height refers to the longest vertical dimension when cell 104-A is positioned upright. The foam layer 106 can be disposed at the bottom end, a top end or center of the cell 104-A.
[0035] In a particular embodiment, the foam layer 106 might also be employed to achieve desired properties to enable thermal insulation between the cells 104-A. As the cells 104-A function and produce heat, the foam layer 106 acts as a thermal insulation. Such property of the foam layer 106 aids in maintaining a consistent and safer temperature profile throughout the battery pack 100, ensuring longevity and reducing potential risks associated with overheating. In an embodiment, thermal insulation property of the foam layer 106 can be improvised through one or more additional techniques such as infusing aerogel particles into the foam matrix, use of closed-cell structural geometry of foam layer 106, incorporation of nanoparticles like graphene, carbon nanotubes, or metal oxide particles into the foam matrix, multi-layered foam layer 106, and the like.
[0036] In another embodiment, battery pack 100 is equipped with the thermal interface material (TIM) 108. The TIM 108 is positioned to cover both a top surface 106-A and a bottom surface 106-B, of the foam layer 106, making TIM 108 an essential component in the battery pack. The TIM 108 acts as a thermal conduit, efficiently pulling away the heat generated by the cells 104-A and dispersing the heat across the foam layer 106. The distribution mechanism facilitates rapid and consistent heat dissipation for maintaining optimal battery performance. Further, the TIM 108 is designed to extend up to a second predetermined level of the cell height. Such deliberate design ensures that a vast portion of the cell 104-A is covered by the TIM 108, optimizing its capability to manage and distribute heat. The disposal of TIM 108 on both sides of the foam layer 106 can address several technical problems such as (a) TIM 108, when placed on both sides of the foam 106, facilitates efficient heat transfer away from the cells 104-A, distributing heat uniformly across the foam layer 106 to prevent the concentration of heat in specific regions to enhance both safety and performance of the battery pack, (b) a symmetrical thermal distribution can be achieved, ensuring consistent temperature profiles across entirety of battery pack, (c) optimal thermal distribution across cell height can extend the overall life of the cell, and (d) TIM 108 can rapidly draw away and disperse the heat generated, ensuring the each cell 104-A remains within safe operational temperatures even under demanding conditions.
[0037] In another embodiment of the battery pack 100, the performance of the TIM 108 is augmented by the strategic integration of the first separator 110 and the second separator 112. The first separator 110 and the second separator 112 are positioned to collaborate with the TIM 108. Specifically, the first separator 110 is situated between the TIM 108 and the top surface 106-A of the foam layer 106, while the second separator 112 is placed between the TIM 108 and the bottom surface 106-B of the foam layer 106. Crafted from materials like natural rubber, silicon rubber, ceramic composite, or polyethylene oxide, among others the first separator 110 and the second separator 112 play an essential role. The first separator 110 and the second separator 112 serve as protective barriers, ensuring that the TIM 108 remains confined within its defined boundaries. The placement of the first separator 110 and the second separator 112 prevents any unwanted lateral movement, overflow, or seepage of the TIM 108 into the foam layer 106. Through the integration of the first separator 110 and the second separator 112 in such

specific arrangement, the structural integrity and design intent of the battery pack 100 are maintained, assuring that the TIM 108 consistently delivers optimal performance.
[0038] Each of first separator 110 and the second separator 112 can resolve a variety of technical challenges such as to:
(a) prevent chemical or physical interactions between the TIM 108 and the foam layer 106. The chemical or physical interactions might deteriorate the effectiveness of the TIM 108, or compromise the integrity and cushioning ability of the foam layer 106.
(b) provide barrier effect to prevent seeping of gel-like or liquid like TIM 108 into the foam layer 106. Thus, TIM 108 can stay in its designated place and does not infiltrate the foam layer 106.
(c) safeguard the foam layer 106 from degradation product of TIM 108 to ensure longevity and consistent performance of the foam layer 106 in protecting the cells 104-A.
[0039] In a distinct embodiment, the battery pack 100 may employ the first separator 110 or the second separator 112 constructed from an array of materials, including natural rubber, silicon rubber, ceramic composites, polyethylene oxide, and even more components like glass fiber, silica glass, polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, and polyacrylate. These materials can be used individually or combined to achieve desired properties. Beyond their compositional variance, the first separator 110 and the second separator 112 possess numerous functions within the battery pack 100. The separation ensures the safety of the battery pack 100 by reducing the potential risks associated with component interaction, like short circuits, which could compromise the efficiency and durability of the battery pack 100.
[0040] In another embodiment, the TIM 108 may showcase a composition, incorporating materials tailored to optimize the thermal management of battery pack 100. Notably, the TIM 108 can be formulated using phase change materials (PCMs) known for their capacity to absorb and release heat during phase transitions, ensuring that the temperature of the battery pack 100 remains stable during operations. Additionally, potting materials may be introduced into the composition of TIM 108, offering variants such as epoxy, silicone, and urethane. Inclusion of potting material in the TIM 108 not only promotes effective heat transfer between the cells 104-A and their surroundings but also aids in encapsulating and protecting the battery pack 100 components, ensuring a balance of safety and performance in the operation of battery pack 100. Combining TIM 108 with a potting material offers enhanced thermal conductivity and improved protection against environmental factors, physical shocks, or potential contaminants. The potting material acts as an electrical insulator, and guides the heat effectively through the TIM 108.
[0041] Within an exemplary embodiment, the TIM 108 may utilize the unique properties of PCMs. The PCMs can be categorized into organic PCM (e.g., paraffin, long chain fatty acids etc.), inorganic (e.g., metal such as gallium, and salt hydrates such as sodium sulfate decahydrate (Glauber’s salt) and disodium hydrogen phosphate dodecahydrate), or eutectic PCM (e.g., mixture of CaCl2·6H2O and Na2SO4·10H2O), each offering distinct thermal characteristics. PCMs excel in capturing and dispersing thermal energy during their phase transitions, be it from solid to liquid or vice versa. Such dynamic ability enables the PCMs in the TIM 108 to absorb the heat produced by the cells 104-A, effectively moderating the temperature within the battery pack 100. Such a temperature regulation mechanism is pivotal, as it directly influences the longevity, safety, and overall performance of the battery pack 100, ensuring that it operates within the desired thermal parameters.
[0042] In one embodiment, a notable feature of the TIM 108 may be the direct physical engagement with cells 104-A. By being in direct contact with the cells 104-A, the TIM 108 can be better positioned to quickly and efficiently draw away the heat generated by the cells 104-A. Such an efficient heat transfer mechanism ensures that the cumulative heat within the battery pack 100 does not surpass safe thresholds. Such design choice not only extends the life span of the cells 104-A by reducing thermal stress but also bolsters the overall safety of the battery pack 100, minimizing the risk of overheating or potential thermal runaway scenarios. Utilizing two discrete layers of TIM 108 separated by foam layer 106, instead of a single continuous layer of TIM 108, to cool down the cells 104-A, offers multiple advantages. The dual layers of TIM 108 ensure that heat is extracted, simultaneously, from both the top and bottom portion of the cells 104-A to enable uniform temperature distribution across the cell 104-A. Further, foam layer 106 acts as an insulator between the two layers of TIM 108, preventing potential heat buildup and further ensuring efficient heat transfer from the cells 104-A.
[0043] The bilayer arrangement of TIM enhances the fault tolerant behavior of the battery pack. Notably, if fault happens at top TIM layer, bottom layer continues functioning, thereby disclosed battery pack remains functional. In a similar manner, if fault happens at bottom layer, top layer continues functioning, thereby disclosed battery pack remains functional. Person ordinarily skilled in the art would appreciate that instead of multilayered structure (of present disclosure), one layer of TIM (as disclosed in the prior art) could endanger the entire cell, and ultimately, the battery pack 100. The reason for endanger is the presence of only one TIM layer, which if becomes faulty, no safety way out can be provided to the cell.
[0044] Separate layers of TIM 108 with foam layer 106, would enable weight reduction due to lesser amount of dense material of TIM 10.8. Discrete layers of TIM 108 allow the possibility to use different materials of TIM 108 (with different thermal properties) for each layer, thereby, optimizing the thermal management based on specific requirements. Two separate materials of TIM 108 can be beneficial for efficient heat management during the charging and discharging cycle. During charging, lithium ions move from the cathode (positive electrode) to the anode (negative electrode). The electrochemical reactions taking place at the electrodes can produce heat. Given the closer proximity to the positive terminal, the cathode might contribute more to the heating at that end during the charging process. During discharge, the ions move in the opposite direction, but the heat generation patterns might remain similar due to the distribution of internal resistances. Thus, first layer of TIM 108 towards cathode can have higher thermal conductivity in comparison to second layer of TIM 108 towards anode. Thus, a discre te layer of TIM 108 can improve heat management, particularly during charging at higher input and/or discharge at higher load.
[0045] Within an embodiment of the battery pack 100, the foam layer 106 may be positioned to extend up to a first predetermined level of the cell height. The height of foam layer 106 is very critical for efficient thermal management of battery back 100. Excessive amount of foam in the foam layer 106 may retain too much heat, thereby exacerbating the situation if the internal temperature (of cells 104-A) starts to rise. So, the height of the foam layer 106 needs to be optimized. The foam layer 106 may range from 10% to 70% (which can be selected from a distinct range of 10% to 20%, 21% to 30%, 31% to 40%, 41% to 50%, 51% to 60% and 61% to 70%). Such provision allows for varying degrees of foam layer 106’s height, accommodating different design priorities, whether it is focused on maximizing thermal dispersion, optimizing physical protection, or balancing the two. The flexibility in height of foam layer 106 offered by the above range ensures that manufacturers can tailor the battery pack 100 for specific use cases, thermal environments, or performance requirements. In an aspect, if the first predetermined level of the cell height is lesser than 10%, the foam layer 106 may not be thick enough to withstand the heat release by the cell 104-A. Whereas, if the second predetermined level of the cell height is greater than 70%, the foam layer 106 may occupy a larger space within the housing 102, thereby affecting the structural integrity of the battery pack 100.
[0046] In an embodiment, the TIM 108 may be disposed up to a second predetermined level of the cell height. TIM 108 is designed to provide enhanced thermal pathway between cell 104-A and surroundings or cooling system to prevent the onset of thermal runaway. Thus, the optimum level of TIM 108 is very significant for thermal management. Excessive TIM 108 may increase weight and cost, whereas too light TIM 108 may not achieve objective (i.e., efficient thermal management). In this particular embodiment, the second predetermined level may vary between 16% to 86% (which can be selected from a distinct range of 16% to 26%, 27% to 36%, 37% to 46%, 47% to 56%, 57% to 66%, 67% to 76% and 77% to 86%) of cell height. TIM 108 is disposed on both sides of the foam layer 106, height of each side may be selected in such a way that height of TIM 108 would be 16% to 86% height. In simpler terms, each of the first layer of TIM 108 (disposed above foam layer 106) and the second layer of TIM 108 (disposed below foam layer 106) would contribute half the total of the second predetermined level. In an embodiment, the first and second layer of TIM 108 may have different heights. Depending on specific thermal management needs, the TIM 108 can cover a minimal portion of the cell height for localized cooling or span most of the cell height for thermal management, ensuring the efficacy of battery pack 100 across diverse operational scenarios. In an aspect, if the second predetermined level of the cell height is lesser than 16%, the TIM 108 may not be thick enough to withstand the heat release by the cell 104-A. Whereas, if the second predetermined level of the cell height is greater than 86%, the TIM 108 may occupy a larger space within the housing 102, thereby affecting the structural integrity of the battery pack 100.
[0047] In a particular embodiment, the first separator 110, may be positioned between the TIM 108 and the top surface 106-A of the foam layer 106, maintaining a specific gap to ensure the optimal function of both components. The gap can be calibrated as a fraction of the cell height, ranging from 2% to 10% (which can be selected from a distinct range of 2% to 5%, 6% to 8% and 9% to 10%). By maintaining the specific gap, the first separator 110 assures that the TIM 108 remains effective in drawing away heat from the cells 104-A, while the foam layer 106 aids in dissipating the heat. The specified range grants designers the latitude to optimize the battery pack 100 for specific conditions, balancing the need for immediate heat transfer with the benefits of broader heat dissipation across the foam layer 106. If the specific gap between the TIM 108 and the top surface 106-A is less than 2%, the first separator 110 may not prevent fusion between the TIM 108 and the foam layer 106. Whereas, if the specific gap between the TIM 108 and the top surface 106-A is greater than 10%, the first separator 110 may occupy a larger space within the housing 102, thereby affecting the structural integrity of the battery pack 100.
[0048] In an embodiment, the second separator 112 is positioned between the TIM 108 and the bottom surface 106-B of the foam layer 106. The second separator 112 may serve to maintain a precise gap that ensures the efficient operation of these two critical components. The precise gap may be defined as a percentage of the cell height and, in this context, varies between 2% to 10% (which can be selected from a distinct range of 2% to 5%, 6% to 8% and 9% to 10%). Such a design ensures that the TIM 108 remains unobstructed from collecting and dispersing heat from the cells 104-A. Meanwhile, the foam layer 106 beneath efficiently diffuses the heat, preventing potential hotspots. The flexibility offered by the range enables manufacturers to fine-tune the battery pack 100 for diverse thermal requirements and operational scenarios. If the specific gap between the TIM 108 and the bottom surface 106-B is less than 2%, the second separator 112 may not prevent fusion between the TIM 108 and the foam layer 106. Whereas, if the specific gap between the TIM 108 and the bottom surface 106-B is greater than 10%, the second separator 112 may occupy a larger space within the housing 102, thereby affecting the structural integrity of the battery pack 100.
[0049] In an embodiment, originating from the top surface 106-A of the foam layer 106, the TIM 108 may project upwards in a specific direction. The ascent of TIM 108 may be calibrated to stop at a particular point, which may be a third predetermined level of the cell height. The endpoint of TIM 108 maintains a carefully measured gap, a first pre-defined distance, from the inner surface of the battery pack 100’s top casing, part of housing 102. The intentional space between the TIM 108’s topmost point and the top casing ensures optimal thermal dispersion, preventing heat accumulation while safeguarding the structural and functional aspects of the battery pack 100.
[0050] In an embodiment, the TIM 108 may extend in the upward direction (till the third predetermined level) from the top surface 106-A of the foam layer 106, specifically engineered to achieve a height that ranges between 16% to 86% (which can be selected from a distinct range of 16% to 26%, 27% to 36%, 37% to 46%, 47% to 56%, 57% to 66%, 67% to 76% and 77% to 86%) of the overall cell height. Such specific orientation and depth may be pivotal as they facilitate enhanced thermal management, ensuring that heat generated by the cells 104-A is effectively dissipated and thereby preventing thermal runaway events. The design range of 16% to 86% provides flexibility for various battery pack configurations while ensuring that optimal heat transfer efficiency is maintained. In an aspect, if the third predetermined level of the cell height is lesser than 16%, the TIM 108 may not be thick enough to withstand the heat release by the cell 104-A. Whereas, if the third predetermined level of the cell height is greater than 86%, the TIM 108 may occupy a larger space within the housing 102, thereby affecting the structural integrity of the battery pack 100.
[0051] In an embodiment, the TIM 108 may extend in a downward direction from the bottom surface 106-B of the foam layer 106, reaching a depth characterized as the fourth predetermined level of the cell height. Such strategic orientation may ensure enhanced heat dissipation from the bottom of the cells 104-A, further optimizing thermal management. Moreover, the fourth predetermined level may be distanced from the bottom casing of the housing 102 by a second pre-defined distance. Such intentional separation safeguards the cells 104-A from potential heat buildup at the base, provides a buffer against external temperature influences, and allows for improved ventilation and cooling.
[0052] In one configuration, the TIM 108 may project downward from the bottom surface 106-B of the foam layer 106, specifically reaching a depth, termed as the fourth predetermined level, that spans between 16% and 86% of the cell height. Such depth can be fine-tuned from a spectrum of options, namely 16% to 26%, 27% to 36%, 37% to 46%, 47% to 56%, 57% to 66%, 67% to 76%, and 77% to 86%. The deliberate design and placement play a critical role in thermal regulation, ensuring efficient heat dispersion from cells 104-A and subsequently minimizing risks of thermal runaways. The breadth of the 16% to 86% range offers adaptability to different battery pack structures, all the while preserving excellent heat transference efficacy. In an aspect, if the fourth predetermined level of the cell height is lesser than 16%, the TIM 108 may not be thick enough to withstand the heat release by the cell 104-A. Whereas, if the fourth predetermined level of the cell height is greater than 86%, the TIM 108 may occupy a larger space within the housing 102, thereby affecting the structural integrity of the battery pack 100.
[0053] FIG. 2 illustrates a method 200 for assembling a battery pack, in accordance with an embodiment of the present disclosure. A series of steps are outlined to ensure the effective arrangement of components within the housing, promoting efficient thermal management and safety. At step 202, the process begins with the provision of a housing that is specifically designed to house multiple cells. Step 204 involves the careful positioning of the battery cells inside the housing. Such positioning ensures that each cell is adequately spaced apart from the others, maintaining a predefined gap between them. Such spatial arrangement is essential to prevent any physical contact or potential short circuits between the cells. At step 206, to enhance thermal management, a foam layer is introduced within the housing. The foam layer serves as an insulator and heat dissipate or, helping to regulate the operating temperature of the battery pack. It's crucial to position the foam layer in a way that it extends up to a specific height within each battery cell. The specific height corresponds to a first predetermined level, which is carefully chosen to optimize thermal performance. At step 208, the subsequent step involves the application of a thermal interface material (TIM) to the top and bottom surfaces of the foam layer. The TIM facilitates efficient heat transfer between the battery cells and the surrounding environment. Similar to the foam layer, the TIM's extent is controlled by a predetermined height within each cell, referred to as the second predetermined level. At step 210, the assembly involves the precise placement of a first separator atop the foam layer. The separator functions to physically separate the TIM from the top surface of the foam layer. The separation ensures that the TIM's effectiveness in heat transfer is not compromised by direct contact with other components. At step 212, a second separator is positioned beneath the foam layer. The second separator serves the purpose of isolating the TIM from the bottom surface of the foam layer. Maintaining the separation is essential for preventing any thermal interference or inefficiencies in heat distribution.
[0054] FIG. 3 showcases a top view of the battery pack 100, as per an embodiment presented in the current disclosure. The top view may highlight the internal configuration of the battery pack 100, revealing the plurality of cells 104-A, all encapsulated within the housing 102. The predefined gap between each cell 104-A may be filled with two distinct materials—the foam layer 106, and the TIM 108. The foam layer 106 and TIM 108 collectively work in tandem, with their function being to counteract the effects of heat. More specifically, the presence of foam layer 106 and TIM 108 may be utilized in either completely preventing or at the very least, reducing the adverse heat spread caused by a phenomenon known as thermal runaway, which is a rapid, uncontrolled temperature escalation that can compromise the safety and performance of battery pack 100.
[0055] FIG. 4 presents a front view of the battery pack 100, aligned with an embodiment outlined in the disclosure. As illustrated, the predefined gap within the battery pack 100 may be filled with a plurality of materials, each chosen for its unique properties. Among these materials are foam, the thermal interface material, and separators, to name a few. By integrating these materials in a deliberate sequence, the design prioritizes two primary objectives. First, the design actively combats the challenge of heat propagation. Heat, if unchecked, can compromise the efficiency and safety of battery pack 100. These materials, especially the TIM, act as barriers to hinder the spread of heat, ensuring stable performance. Secondly, beyond just thermal performance the choice and placement of these materials also bolster the structural solidity of battery pack 100. The TIM plays assist in averting thermal propagation, by preventing transfer of heat between cells and triggering one another from state of thermal runaway to cause thermal propagation, thereby contributing to the overall safety and stability of the battery pack. The layering not only guards against the detrimental impacts of temperature fluctuations but also reinforces the overall physical resilience of battery pack 100, ensuring it stands robust against potential external or internal stressors.
[0056] FIG. 5 illustrates an exploded view of the battery pack 100, consistent with a specified embodiment from the ongoing disclosure. The illustration deconstructs the battery pack 100, laying out each component for a clear examination. Central to the design are the cells 104-A, surrounded by several layers aimed at ensuring optimal battery performance: the foam layer 106, serving as an initial barrier and cushion; the TIM 108, a critical component for thermal management; followed by a dual-layer of separators—first separator 110 and second separator 112—that offer added layers of insulation and protection. Encasing all these components is the housing 102 that can comprise a top casing and a bottom casing. Together, the top casing and the bottom casing may encapsulate and protect the internal components from the top and bottom side, ensuring both structural integrity and offering a safeguard against external adversities.
[0057] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
[0058] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C … and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.

CLAIMS
What is claimed is:
1. A battery pack, comprising:
a housing;
a plurality of cells placed inside the housing, wherein the plurality of cells are spaced apart from each other by a predefined gap;
a foam layer disposed inside the housing up to a first predetermined level of a cell height;
a thermal interface material (TIM) disposed at a top surface and a bottom surface of the foam layer, wherein the TIM extends up to a second predetermined level of the cell height;
a first separator separates the TIM and the top surface of the foam layer; and
a second separator separates the TIM and the bottom surface of the foam layer.
2. The battery pack as claimed in claim 1, wherein the foam layer comprises one of: a polyurethane foam, a polyethylene foam, a rubber foam, a silicone foam, a polyvinyl chloride foam or a combination thereof.
3. The battery pack as claimed in claim 1, wherein the first separator or the second separator comprises one of: a natural rubber, a silicon rubber, a ceramic composite, a polyethylene oxide, a glass fibre, a silica glass, a polyethylene, a polypropylene, a polyethylene terephthalate, a polyvinyl chloride, a polyacrylate or a combination thereof.
4. The battery pack as claimed in claim 1, wherein the TIM comprises one of a phase change material (PCM) and a potting material.
5. The battery pack as claimed in claim 4, wherein the potting material includes at least one of an epoxy, a silicone, and a urethane.
6. The battery pack as claimed in claim 4, wherein the phase change material (PCM) includes at least one of organic PCMs, inorganic PCMs, and eutectic PCMs.
7. The battery pack as claimed in claim 1, wherein the TIM is in physical contact with a plurality of cells of the battery pack.
8. The battery pack as claimed in claim 1, wherein the first predetermined level is 10% to 70%.
9. The battery pack as claimed in claim 1, wherein the second predetermined level is 16 % to 86 %.
10. The battery pack as claimed in claim 1, wherein the first separator separates the TIM and the foam layer with a distance of 2 % to 10 % of the cell height.
11. The battery pack as claimed in claim 1, wherein the second separator separates the TIM and the foam layer with the distance of 2 % to 10 % of the cell height.
12. The battery pack as claimed in claim 1, wherein the TIM extends, towards an upward direction from the top surface, up to a third predetermined level of the cell height.
13. The battery pack as claimed in claim 12, wherein the third predetermined level is 16 % to 86 %.
14. The battery pack as claimed in claim 1, wherein the TIM extends, towards downward direction from the bottom surface, up to a fourth predetermined level of the cell height.
15. The battery pack as claimed in claim 14, wherein the fourth predetermined level is 16 % to 86 %.
16. A method for assembling a battery pack, the method comprising:
receiving, a plurality of cells inside a housing, wherein the plurality of cells are spaced apart from each other by a predefined gap;
providing a foam layer inside the housing up to a first predetermined level of a cell height;
applying a thermal interface material (TIM) at a top surface and a bottom surface of the foam layer, wherein the TIM extends up to a second predetermined level of the cell height;
disposing a first separator to separate the TIM and the top surface of the foam layer; and
disposing a second separator to separate the TIM and the bottom surface of the foam layer.

SYSTEM AND METHOD FOR PREVENTION OF THERMAL PROPAGATION IN BATTERY PACK

ABSTRACT
The present disclosure provides a battery pack with improved structural integrity and thermal management to eliminate thermal propagation. The battery pack comprises a housing containing a plurality of cells, which are disposed spaced apart by a predefined gap. Further, a foam layer extends up to a first predetermined level of cell height, to provide thermal insulation and mechanical stability. TIM material is arranged at both the top and bottom surfaces of the foam layer, extending up to a second predetermined level of cell height. Further, a first separator segregates the TIM from the top surface of the foam layer, while a second separator segregates at the bottom surface of the foam layer, thereby forming a multi-layered structure The multi-layered structure improved thermal regulation by hindering heat propagation across the cells, and also provide protection against potential thermal runaway.
Fig. 1 , Claims:CLAIMS
What is claimed is:
1. A battery pack, comprising:
a housing;
a plurality of cells placed inside the housing, wherein the plurality of cells are spaced apart from each other by a predefined gap;
a foam layer disposed inside the housing up to a first predetermined level of a cell height;
a thermal interface material (TIM) disposed at a top surface and a bottom surface of the foam layer, wherein the TIM extends up to a second predetermined level of the cell height;
a first separator separates the TIM and the top surface of the foam layer; and
a second separator separates the TIM and the bottom surface of the foam layer.
2. The battery pack as claimed in claim 1, wherein the foam layer comprises one of: a polyurethane foam, a polyethylene foam, a rubber foam, a silicone foam, a polyvinyl chloride foam or a combination thereof.
3. The battery pack as claimed in claim 1, wherein the first separator or the second separator comprises one of: a natural rubber, a silicon rubber, a ceramic composite, a polyethylene oxide, a glass fibre, a silica glass, a polyethylene, a polypropylene, a polyethylene terephthalate, a polyvinyl chloride, a polyacrylate or a combination thereof.
4. The battery pack as claimed in claim 1, wherein the TIM comprises one of a phase change material (PCM) and a potting material.
5. The battery pack as claimed in claim 4, wherein the potting material includes at least one of an epoxy, a silicone, and a urethane.
6. The battery pack as claimed in claim 4, wherein the phase change material (PCM) includes at least one of organic PCMs, inorganic PCMs, and eutectic PCMs.
7. The battery pack as claimed in claim 1, wherein the TIM is in physical contact with a plurality of cells of the battery pack.
8. The battery pack as claimed in claim 1, wherein the first predetermined level is 10% to 70%.
9. The battery pack as claimed in claim 1, wherein the second predetermined level is 16 % to 86 %.
10. The battery pack as claimed in claim 1, wherein the first separator separates the TIM and the foam layer with a distance of 2 % to 10 % of the cell height.
11. The battery pack as claimed in claim 1, wherein the second separator separates the TIM and the foam layer with the distance of 2 % to 10 % of the cell height.
12. The battery pack as claimed in claim 1, wherein the TIM extends, towards an upward direction from the top surface, up to a third predetermined level of the cell height.
13. The battery pack as claimed in claim 12, wherein the third predetermined level is 16 % to 86 %.
14. The battery pack as claimed in claim 1, wherein the TIM extends, towards downward direction from the bottom surface, up to a fourth predetermined level of the cell height.
15. The battery pack as claimed in claim 14, wherein the fourth predetermined level is 16 % to 86 %.
16. A method for assembling a battery pack, the method comprising:
receiving, a plurality of cells inside a housing, wherein the plurality of cells are spaced apart from each other by a predefined gap;
providing a foam layer inside the housing up to a first predetermined level of a cell height;
applying a thermal interface material (TIM) at a top surface and a bottom surface of the foam layer, wherein the TIM extends up to a second predetermined level of the cell height;
disposing a first separator to separate the TIM and the top surface of the foam layer; and
disposing a second separator to separate the TIM and the bottom surface of the foam layer.