DESC:FIELD OF THE INVENTION
[0001] The present invention is generally related to a battery pack, and, more particularly, to a battery pack and a method of assembling the battery pack for sealing a thermal interface material (such as Phase Change Material (PCM) or dielectric liquid) used to thermally manage the battery pack in order to increase the battery life, thereby providing the structural rigidity to prevent undesired movement of plurality of cylindrical cells.
BACKGROUND OF THE INVENTION
[0002] A battery is a combination of two or more cells with external connections in order to produce electricity for powering electric devices. They are being used for ages. They are useful in everyday life, from providing the initial power needed to start the electronic devices like electric vehicles, mobile devices, laptops, etc. to acting as a backup source of electricity in telecommunications, public transportation, medical procedures, domestic power inverters, and solar panel batteries, etc.
[0003] Battery thermal management is important for the safe and efficient operation of batteries. The battery thermal management is responsible for managing or dissipating the heat generated during the electromechanical process occurring in cells. There are many types of batteries, such as - Li-ion, Nickle-Cadmium, Alkaline, Zinc Carbon, etc. As per the advancement of technology, some batteries are rechargeable by plugging them into charging and some batteries are non-rechargeable or single-use.
[0004] During operation, such as charging or discharging the batteries, the cells generate heat that impacts the overall performance of the battery or a battery pack. Thus, to maintain desired performance, it is essential to maintain the temperature within a prescribed range. Conventionally, for thermal management of batteries, a thermal interface material such as phase change materials (PCM) or a dielectric liquid is dispensed in direct contact with the cells. The thermal interface material is to absorb and dissipate the generated heat from the cells
[0005] The thermal interface material is effective in the thermal management of the battery pack. If the thermal interface material is not sealed properly, it may leak and result in damage of electronic components inside the battery pack, blockage of the gas vent path and thereby the gases in the thermal runaway event, reduced life, and so on. Therefore, it is vital for the performance and life of the battery pack that the thermal interface material is sealed properly and that there is no leakage inside the battery pack. Also, in the battery pack, cells are spaced out from each other to avoid an electrical short circuit between adjacent cells. It is important that the cells are retained in their position and prevented from any undesired movement in order to ensure the safety and reliability of the battery pack.
[0006] US10644282B2 discloses a staggered battery cell array with two-dimensional inline terminal edges. An energy storage device including a staggered energy storage cell internal array with two-dimensional inline terminal edges is provided. The energy storage cells in a battery module may be staggered in an internal array, such that a first row of cells in a line are spaced apart, or offset, in a first direction from an immediately adjacent second row of cells in a line, and wherein a first cell in the second row of cells is offset from a first cell in the first row of cells in a second direction orthogonal to the first direction. In some cases, at least two adjacent rows in the battery module may include energy storage cells that are offset from one another but aligned in one direction, such as, the second direction. A mechanical frame may define the arrangement of the energy storage cells relative to one another.
[0007] Conventionally, there exist various systems and methods for preventing the leakage of a thermal interface material used for thermally managing the battery pack. However, in order to achieve the objective, a battery pack with properly sealed thermal interface material is used for improving the performance and life of the battery pack.
[0008] In order to overcome the aforementioned drawbacks, there is a need to provide a battery pack and a method of assembling the battery that is an enhancement to the conventional system. This method is capable of providing structural rigidity to prevent undesired movement of plurality of cylindrical cells placed inside the battery pack. This method is also used for sealing the thermal interface material to prevent leakage, thereby reducing the risk of physical damage to the plurality of cylindrical cells or short circuit.
OBJECTS OF THE INVENTION
[0009] The principal object of the present invention is to overcome the disadvantage of the prior art.
[0010] Another object of the present invention is to provide a battery pack that provides sealing to a thermal interface material in order to provide the structural rigidity to prevent undesired movement of plurality of cylindrical cells.
[0011] Another object of the present invention is to provide a battery pack that helps in protecting the plurality of cylindrical cells from mechanical shocks and vibrations which is helpful in damaging the cells.
[0012] Another object of the present invention is to provide a method for assembling a battery pack that helps in improving the thermal performance of the battery pack by enabling direct contact of the thermal interface materials with the plurality of cylindrical cells in the battery pack.
[0013] Another object of the present invention is to provide a method for assembling a battery pack that is cost-effective because of combining the function of holding the cells and sealing the thermal interface material into one functional element.
[0014] Another object of the present invention is to provide a battery pack and a method for assembling a battery pack that improves the safety of the pack by providing a clear path for gases to escape the battery pack in a thermal runaway event.
SUMMARY OF THE INVENTION
[0015] The present invention relates to a battery pack and a method for assembling a battery pack for sealing the thermal interface material in order to thermally manage the battery pack while also providing the structural rigidity to prevent undesired movement of cells and insulating them electrically from each other to prevent a short circuit.
[0016] According to an embodiment of the present invention, a battery pack comprising, a battery casing defining a cavity, plurality of cylindrical cells placed inside the cavity through a robot or jig and held in position inside the cavity through an adhesive layer that is dispensed on a bottom plate of the battery casing, wherein the plurality of cylindrical cells that is at least one of a Li-ion cells, dry cells, a lead-acid cells, and a dry/electrochemical cell are spaced apart from each other by defining a gap in between the plurality of cylindrical cells, a thermal interface material that is at least one of a Phase Change Material (PCM), and a dielectric liquid filled inside the cavity to a predetermined level that is determined based on the heat generated by the plurality of cylindrical cells and the heat gradient, wherein the thermal interface material is in direct contact with the plurality of cylindrical cells in order to absorb and dissipate the heat generated in the plurality of cylindrical cells, wherein the battery casing and the plurality of cylindrical cells are filled with the thermal interface material by providing a clear path for gases to escape the battery pack in a thermal runway event.
[0017] According to an another embodiment of the present invention, the battery pack further comprising, a foam layer placed above the thermal interface material and the sealing layer, wherein the foam layer is chosen with low density to allow air passage during volume change in the thermal interface material during the battery pack creation, and a sealing layer that may be chosen from a polymeric material that includes but not limited to a potting material, a thermosetting plastic such as epoxy, polyurethane or silicone, a thermoplastic or an elastomer, and a non-polymer material dispensed above the foam layer and in the gap in between the plurality of cylindrical cells, wherein the sealing layer is dispersed at multiple locations inside the battery pack, instead of pouring it from only one location, to prevent its coagulation at a particular location inside the cavity and it is used to provide structural rigidity to hold the plurality of cylindrical cells in position in order to withstand vibrations and mechanical shocks, wherein the foam layer provides a platform for the sealing layer to be poured on, prevents the sealing layer from flowing below and the foam layer also acts as an air gap in between the thermal interface material and the sealing layer during the battery pack operation to ensure seal is intact.
[0018] According to an another embodiment of the present invention, a method of assembling the battery pack comprising, entrenching a battery casing with a cavity, placing plurality of cylindrical cells into the cavity through a robot or jig and held in position inside the cavity through an adhesive layer that is dispensed on a bottom plate of the battery casing such that there is a gap in between the plurality of cylindrical cells, wherein the plurality of cylindrical cells that is at least one of a Li-ion cells, dry cells, a lead-acid cells, and a dry/electrochemical cell, filling a thermal interface material that is at least one of a Phase Change Material (PCM), and a dielectric liquid to a predetermined level into the cavity, wherein the predetermined level is determined based on the heat generated by the plurality of cylindrical cells and the heat gradient, wherein the battery casing and the plurality of cylindrical cells are filled with the thermal interface material by providing a clear path for gases to escape the battery pack in a thermal runway event.
[0019] According to an another embodiment of the present invention, a method of assembling the battery pack further comprising, placing a foam layer above the thermal interface material, wherein the foam layer is chosen with low density to allow air passage during volume change in the thermal interface material during the battery pack creation, and dispensing a sealing layer that may be chosen from a polymeric material that includes but not limited to a potting material, a thermosetting plastic such as epoxy, polyurethane or silicone, a thermoplastic or an elastomer, and a non-polymer material above the foam layer and into the gap to provide sealing for the thermal interface material and structural rigidity to hold the plurality of cylindrical cells, wherein the sealing layer is dispersed at multiple locations inside the battery pack, instead of pouring it from only one location, to prevent its coagulation at a particular location inside the cavity in order to withstand vibrations and mechanical shocks, wherein the foam layer provides a platform for the sealing layer to be poured on and prevents the sealing layer from flowing below and the foam layer also acts as an air gap in between the thermal interface material and the sealing layer during the battery pack operation to ensure seal is intact.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The accompanying drawings illustrate various embodiments of systems, methods, and embodiments of various other aspects of the disclosure. Any person with ordinary skills in the art will appreciate that the illustrated element boundaries (e.g. boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. It may be that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of one element may be implemented as an external component in another, and vice versa. Furthermore, elements may not be drawn to scale. Non-limiting and non-exhaustive descriptions /are described with reference to the following drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating principles.
[0021] Fig.1 illustrates a cross section view of a battery pack, according to an embodiment of a present invention;
[0022] Fig.2 illustrates an exploded perspective view of the battery pack, according to an embodiment of a present invention; and
[0023] Fig.3 illustrates a flowchart depicting a method 300, according to an embodiment of a present invention.
DETAILED DESCRIPTION
[0024] Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings in which, like numerals represent like elements throughout the several figures, and in which example embodiments are shown. Embodiments of the claims may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The examples set forth herein are non-limiting examples and are merely examples among other possible examples.
[0025] Some embodiments of this invention, illustrating all its features, will now be discussed in detail. The words “comprising,” “having,” “containing,” and “including,” and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items or meant to be limited to only the listed item or items.
[0026] It must also be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, the preferred systems and methods are now described.
[0027] The present invention relates to a battery pack and a method for assembling a battery pack for improving the performance of the battery pack by sealing a thermal interface material and also providing structural rigidity to prevent the undesired movement of plurality of cylindrical cells, thereby protecting the plurality of cylindrical cells from mechanical shock and vibration that may cause damage the plurality of cylindrical cells.
[0028] Fig.1 illustrates a cross-section view of the battery pack, according to an embodiment of a present invention. The battery pack includes a battery casing 102 defining a cavity 102a, plurality of cylindrical cells 104 positioned inside the cavity 102a, wherein the plurality of cylindrical cells 104 are spaced apart from each other defining a gap 104a in between the plurality of cylindrical cells, a thermal interface material 106 filled inside the cavity 102a to a predetermined level. In a preferred embodiment, a foam layer 110 is placed above the thermal interface material 106, and a sealing layer 108 is placed above the foam layer 110 and in the gap 104a between the plurality of cylindrical cells 104. In preferred embodiment, the sealing layer 108 may be chosen from a polymeric material that includes but not limited to a thermosetting plastic such as epoxy, polyurethane or silicone, a thermoplastic, or an elastomer. In another embodiment, the sealing layer 108 may be chosen from non-polymeric material. The material for the sealing layer 108 may be chosen based on the thermal interface material 106. For example, the sealing layer 108 may be selected from a material that has chemical compatibility with the thermal interface material 106.
[0029] The battery casing 102 according to an embodiment of the present invention includes a bottom plate and sidewalls extending from the bottom plate to define a cavity 102a. The top of the battery casing 102 includes an opening to provide access to the cavity 102a. The cavity 102a is configured to receive plurality of cylindrical cells 104. The plurality of cylindrical cells 104 is at least one of a Li-ion cells, a dry cells, a lead acid cells, and a dry/electrochemical cell. The number of cells 104 in the battery pack 100 is selected based on the required voltage or current. In an embodiment, the plurality of cells 104 is lowered into the cavity 102a through a robot or jig and held in position inside the cavity through an adhesive layer 112 that is dispensed on the bottom plate. The adhesive layer 112 is mainly supportive during initial stages of assembling the plurality of cylindrical cells 104 in the battery pack 100 to provide the required retention force.
[0030] The thermal interface material 106 is filled into the cavity 102 such that it absorbs and dissipates the heat generated in the plurality of cylindrical cells 104 during operation. In an embodiment, the thermal interface material 106 is in direct contact with the cells 104 and is filled up to a predetermined level in the cavity 102a. The level is determined based on the heat generated by the plurality of cylindrical cells 104 and the heat gradient. In a preferred embodiment, the bottom plate of the battery casing 102 is provided with an inlet through which the thermal interface material 106 may be injected into the cavity 102a and an outlet through which the thermal interface material 106 may be discharged. For example, the thermal interface material 106 may be a flowing dielectric liquid that is injected into the cavity 102a through the inlet and discharged from the cavity 102a through the outlet. In an alternate embodiment, the thermal interface material 106 may be filled into the cavity through the opening at the top of the battery casing 102. For example, the thermal interface material may be a phase change material that is poured into the cavity 102a through the opening in the top of the casing 102. In yet another embodiment, the thermal interface material 106 may be selected from any other heat transfer medium that performs the function of absorbing heat from the plurality of cylindrical cells 104.
[0031] In a preferred embodiment, the foam layer 110 is sandwiched in between the thermal interface layer material 106 and the sealing layer 108 such that the foam layer 110 provides a platform for the sealing layer 108 to be poured on while also sealing the sealing layer 108 and preventing it from flowing below. The sealing layer 108 adheres to the cells and provides the required retention force to hold the plurality of cylindrical cells 104 in position and also acts as a seal for the thermal interface material 106. It should be noted that the sealing layer 108 may be chosen from any material without deterring the intended function of the sealing layer 108 as disclosed in this specification.
[0032] The sealing layer 108 is dispensed above the thermal interface material 106 in the gap 104a in between the plurality of cylindrical cells 104. In a preferred embodiment, the sealing layer 108 is dispensed into the cavity 102a through the opening 102a in casing 102 such that it fills in the gap 104a in between the plurality of cylindrical cells 104. In a preferred embodiment, the foam layer 110 is placed above the thermal interface material 106 and it acts as a platform for the sealing layer 108 to be poured on while also sealing it and preventing it from flowing below. For example, the foam layer 110 may be a polyurethane sheet that is cut using a die to fit into the gap 104a between plurality of cylindrical cells 104 and lowered into the cavity 102a using a jig and held at a position with the help of the interference fit with the plurality of cylindrical cells 104 and casing 102. The foam layer 110 is chosen with low density to allow air passage during volume change in the thermal interface material 106 during the battery pack 100 creation and the foam layer 110 also acts as an air gap in between the thermal interface material 106 and the sealing layer 108 during the battery pack 100 operation to ensure the seal is intact.
[0033] The sealing layer 108 is then dispensed on top of the foam layer 110 so that it provides necessary sealing for the thermal interface material 106 and also provides structural rigidity to hold plurality of cylindrical cells 104 in position. The sealing layer 108 is dispersed at multiple points inside the battery pack 100, instead of pouring it from only one point, to prevent its coagulation in a particular part inside the gap 104a. In a preferred embodiment, the sealing layer 108 is a thermosetting plastic that is poured on top of the foam layer 110 using a dispenser and allowed to cure so that it adheres to the cell surface and the battery casing 102.
[0034] Fig. 2 illustrates an exploded perspective view of the battery pack according to an embodiment of the present invention. The sealing layer 108 is configured to transfer any mechanical load to or from the plurality of cylindrical cells 104 to the battery casing 102 which is then transferred to the frame of the vehicle through the mounts in the battery casing 102(not shown). By having this load transfer path, the sealing layer 108 provides the required structural rigidity and prevents any undesired movement of the plurality of cylindrical cells 104. The sealing layer 108 further closes the opening of the casing 102 thereby providing the sealing for the thermal interface layer 106. Further, the sealing layer 108 also enhances the safety of the pack 100 by providing a clear path for gases to escape the pack in the event of a thermal runaway event. As the thermal interface material 106 is sealed properly, the spillage of the material onto the gas vent path is prevented thereby providing a clear path for gases from plurality of cylindrical cells 104 to escape the battery pack 100. The thermal runaway event is a rapid increase of battery cell temperature and pressure, accompanied by the release of flammable gas. This gas has to be removed quickly so that it doesn’t raise the temperature of other plurality of cylindrical cells 104 in the battery pack 100.
[0035] Fig.3 illustrates a flowchart depicting a method 300, according to an embodiment of a present invention. At block 302, a battery casing 102 defining a cavity 102a, plurality of cylindrical cells are placed 104 into the cavity 102a through a robot or jig and held in position inside the cavity 102a through an adhesive layer 112 that is dispensed on a bottom plate of the battery casing 102 such that there is a gap 104a in between the plurality of cylindrical cells 104, as shown in block 304, at block 306, a thermal interface material 106 is filled to a predetermined level into the cavity 102a, wherein the predetermined level is determined based on the heat generated by the plurality of cylindrical cells 104 and the heat gradient, wherein the battery casing 102 and the plurality of cylindrical cells 104 are filled with the thermal interface material 106 by providing a clear path for gases to escape the battery pack 100 in a thermal runway event, at block 308, and a foam layer 110 is placed above the thermal interface material 106, as shown in block 310, a sealing layer 108 is dispensed above the foam layer 110 and into the gap 104a to provide sealing for the thermal interface material 106 and structural rigidity to hold the plurality of cylindrical cells 104, wherein the sealing layer 108 is dispersed at multiple locations inside the battery pack 100, instead of pouring it from only one location, to prevent its coagulation at a particular location inside the cavity 102a in order to withstand vibrations and mechanical shocks wherein the foam layer 110 provides a platform for the sealing layer 108 to be poured on and prevents the sealing layer 108 from flowing below.
[0036] Moreover, although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
,CLAIMS:We claim,
1. A battery pack, comprising:
a battery casing 102 defining a cavity 102a;
plurality of cylindrical cells 104 placed inside the cavity 102a, wherein the plurality of cylindrical cells 104 are spaced apart from each other by defining a gap 104a in between the plurality of cylindrical cells 104;
a thermal interface material 106 filled inside the cavity 102a to a predetermined level, wherein the thermal interface material 106 is in direct contact with the plurality of cylindrical cells 104 in order to absorb and dissipate the heat generated in the plurality of cylindrical cells 104;
a foam layer 110 placed above the thermal interface material 106; and
a sealing layer 108 dispensed above the foam layer 110 and in the gap 104a in between the plurality of cylindrical cells 104, wherein the sealing layer 108 is used to provide structural rigidity to hold the plurality of cylindrical cells 104 in position in order to withstand vibrations and mechanical shocks.
2. The battery pack 100 as claimed in claim 1, wherein the plurality of cylindrical cells 104 is lowered into the cavity 102a through a robot or jig and held in position inside the cavity 102a through an adhesive layer 112 that is dispensed on a bottom plate of the battery casing 102.
3. The battery pack 100 as claimed in claim 1, wherein the plurality of cylindrical cells 104 is at least one of a Li-ion cells, dry cells, a lead-acid cells, and a dry/electrochemical cell.
4. The battery pack 100 as claimed in claim 1, wherein the thermal interface material 106 is at least one of a Phase Change Material (PCM), and a dielectric liquid and the predetermined level is determined based on the heat generated by the plurality of cylindrical cells 104 and the heat gradient.
5. The battery pack 100 as claimed in claim 1, wherein the battery casing 102 and the plurality of cylindrical cells 104 are filled with the thermal interface material 106 by providing a clear path for gases to escape the battery pack 100 in a thermal runway event.
6. The battery pack 100 as claimed in claim 1, wherein the foam layer 110 provides a platform for the sealing layer 108 to be poured on and prevents the sealing layer 108 from flowing below.
7. The battery pack 100 as claimed in claim 1, wherein the foam layer 110 is chosen with low density to allow air passage during volume change in the thermal interface material 106 during the battery pack 100 creation and the foam layer 110 also acts as an air gap in between the thermal interface material 106 and the sealing layer 108 during the battery pack 100 operation to ensure the seal is intact.
8. The battery pack 100 as claimed in claim 1, wherein the sealing layer 108 may be chosen from a polymeric material that includes but not limited to a potting material, a thermosetting plastic such as epoxy, polyurethane or silicone, a thermoplastic or an elastomer, and a non-polymer material.
9. The battery pack 100 as claimed in claim 1, wherein the sealing layer 108 is dispersed at multiple locations inside the battery pack 100, instead of pouring it from only one location, to prevent its coagulation at a particular location inside the cavity 102a.
10. A method of assembling a battery pack, comprising:
entrenching a battery casing 102 with a cavity 102a;
placing plurality of cylindrical cells 104 into the cavity 102a defining a gap 104a in between the plurality of cylindrical cells 104;
filling a thermal interface material 106 to a predetermined level into the cavity 102a;
placing a foam layer 110 above the thermal interface material 106; and
dispensing a sealing layer 108 above the foam layer 110 and into the gap 104a to provide sealing for the thermal interface material 106 and structural rigidity to hold the plurality of cylindrical cells 104.
11. The method 300 as claimed in claim 10, wherein the plurality of cylindrical cells 104 is lowered into the cavity 102a through a robot or jig and held in position inside the cavity 102a through an adhesive layer 112 that is dispensed on a bottom plate of the battery casing 102.
12. The method 300 as claimed in claim 10, wherein the plurality of cylindrical cells 104 is at least one of a Li-ion cells, dry cells, a lead-acid cells, and a dry/electrochemical cell.
13. The method 300 as claimed in claim 10, wherein the thermal interface material 106 is at least one of a Phase Change Material (PCM), and a dielectric liquid and the predetermined level is determined based on the heat generated by the plurality of cylindrical cells 104 and the heat gradient.
14. The method 300 as claimed in claim 10, wherein the battery casing 102 and the plurality of cylindrical cells 104 are filled with the thermal interface material 106 by providing a clear path for gases to escape the battery pack 100 in a thermal runway event.
15. The method 300 as claimed in claim 10, wherein the foam layer 110 provides a platform to for the sealing layer 108 to be poured on and prevents the sealing layer 108 from flowing below.
16. The method 300 as claimed in claim 10, wherein the foam layer 110 is chosen with low density to allow air passage during volume change in the thermal interface material 106 during the battery pack 100 creation and the foam layer 110 also acts as an air gap in between the thermal interface material 106 and the sealing layer 108 during the battery pack 100 operation to ensure the seal is intact.
17. The method 300 as claimed in claim 10, wherein the sealing layer 108 may be chosen from a polymeric material that includes but not limited to a potting material, a thermosetting plastic such as epoxy, polyurethane or silicone, a thermoplastic or an elastomer, and a non-polymer material
18. The method 300 as claimed in claim 10, wherein the sealing layer 108 is dispersed at multiple locations inside the battery pack 100, instead of pouring it from only one location, to prevent its coagulation at a particular location inside the cavity 102a.