Claims:WE CLAIM:
1. A method for casting cooling channels in battery pack comprising steps of:
a. configuring at least one inlet and corresponding outlet at opposite ends of the battery pack;
b. inserting a polymer substrate strip from the inlet to the outlet;
c. arranging the polymer substrate strip to fill the spaces between the individual cells of battery pack;
d. pouring an encapsulant from plurality of encapsulant dispenser (3) to fill the spaces not occupied by polymer substrate strip after step (c);
e. allowing encapsulant to cure and settle; and
f. removing the polymer substrate strip to define a pathway for the flow of a coolant from inlet to outlet of the battery pack.

2. The method for casting cooling channels in battery pack as claimed in claim 1, wherein the casted cooling channels facilitates direct contact of coolant with the individual cells of the battery pack.

3. The method for casting cooling channels in battery packs as claimed in claim 1, wherein the inlet and outlet are configured along breadth of the battery pack.

4. The method for casting cooling channels in battery packs as claimed in claim 1, wherein the polymer substrate strip is selected from an easily removable/moldable quality or dissolvable property polymers such as but not limited to a Teflon coated substrate (polytetrafluoroethylene), LDPE tube rolls, straw and stack of wires.

5. The method for casting cooling channels in battery packs as claimed in claim 1, wherein the Teflon coated substrate exhibits dimensional changes on changing temperature of the battery, so as to allow Teflon to be easily removed from the casted cooling channel and released from grip of the cured encapsulant.

6. The method for casting cooling channels in battery packs as claimed in claim 1, wherein the polymer substrate strips are inserted between the individual cells in a zigzag fashion into several manifolds.

7. The method for casting cooling channels in battery packs as claimed in claim 1, wherein the encapsulant is selected from but not limited to epoxy, silicone and polyurethane fillers.

8. The method for casting cooling channels in battery packs as claimed in claim 1, wherein the casted cooling channels furnishes battery systems with reduced weight and reduced part counts.

9. The method for casting cooling channels in battery packs as claimed in claim 1, wherein the casted cooling channels maintains battery temperature between 25 to 30 degree.

10. The method for casting cooling channels in battery packs as claimed in claim 1, wherein the casted cooling channels enables tighter packaging of battery modules. , Description:FIELD OF INVENTION
[001] The present invention generally relates to the field of batteries and battery packs. More specifically, the present invention relates to a method of casting cooling channels in battery packs that may be used particularly in vehicular contexts, as well as other applications.

BACKGROUND OF THE INVENTION
[002] Batteries or cells are important energy storage devices well known in the art. The interconnection or arrangement of identical batteries or individual battery cells is termed as battery packs. The plurality of batteries or cells are configured in a series, parallel or a mixture of both to deliver the desired voltage, capacity, or power density. The battery pack generates heat during its operation of working which may lead to create uneven charge/discharge behavior within the pack and the battery pack may begin to lose its capacity or ability to charge or discharge.

[003] In case of electric vehicles (EV), a proper thermal management is essential to maintain adequate and consistent performance of the battery and the vehicle, because excessive temperature negatively affects the battery and hence EV’s performance. EV manufacturers and researchers. Therefore, it is desirable to provide thermal management module or system within the battery packs to prevent premature aging of individual battery cells. The thermal management can be achieved through direct air cooling, or using of flowing liquid coolants, or direct immersion.

[004] In the existing battery packs, the thermal management can be achieved through direct air cooling, or using of flowing liquid coolants, or direct immersion. Among all, the flowing liquid coolant method provides better battery thermal management because they are better at conducting heat away from batteries. The existing liquid coolant method utilizes cooling plates that passes through the battery pack and carries coolant. Hence, the thermal contact with the cells is via thermal transfer material i.e. through the walls of the cold plates. Therefore, the existing liquid coolant method does not provide direct contact of coolant with the individual cells, as the coolant is distributed throughout the battery pack via a cold plates to the battery cells.

[005] Yet another, known way of providing thermal contact of coolant with the cells is through by sandwiching a cooling tube between the cells. This again lacks in providing an effective cooling because of indirect contact with battery cells. The WO2021061741 discloses a thermal management system for a battery pack which includes a plurality of cells arranged into several rows. The coolant flows through the plastic film blanket which is disposed between a row of two batteries. Further, the existing battery packs fails to provide a solution with respect to the problem of thermal runaway. Furthermore, the sandwiching of cooling loops between the cells have their own challenges with respect to assembly of battery packs. It is necessary to mention the process manufacturing of cooling loops utilizes the complex micro extrusion process.

[006] Therefore, it is desirable to provide a method for casting cooling channel for all variety of battery packs having effective cooling capability. Hence, in view of the above problems associated with the state of the art, there is a need of a casting cooling channels in battery packs which provides direct contact of coolant with the individual cells and provides light weighted battery pack systems. Further, it is required to have a method for casting cooling channel that can be utilized in all variety of battery packs.

OBJECTIVE OF THE INVENTION

[007] The primary objective of the present invention is to provide a method for casting cooling channels in battery packs for thermal management.

[008] Another objective of the present invention is to provide cooling channels that allows direct contact of coolant with each cell of battery packs.

[009] Another objective of the present invention is to provide battery packs casted with cooling channels that allows efficient flow of liquid coolant through it.

[0010] Yet another objective of the present invention is to provide a universal casting method which is independent of the type of battery packs and hence can be utilized for casting cooling channels in all varieties of battery packs.

[0011] Yet another objective of the present invention is to provide a casting method which enables reduction in part count and reduces the overall weight of the battery packs.

[0012] Yet another objective of the present invention is to provide an easier and less complex assembly of the battery packs.

[0013] Other objectives and advantages of the present invention will become apparent from the following description taken in connection with the accompanying drawings, wherein, by way of illustration and example, the aspects of the present invention are disclosed.

BRIEF DESCRIPTION OF DRAWINGS
[0014] The present invention will be better understood after reading the following detailed description of the presently preferred aspects thereof with reference to the appended drawings, in which the features, other aspects and advantages of certain exemplary embodiments of the invention will be more apparent from the accompanying drawing in which:

[0015] Figure 1 shows a conventional battery pack system;

[0016] Figure 2 shows an exploded view of a battery system used in an embodiment of the invention;

[0017] Figure 3 illustrates flowchart depicting the steps followed for casting cooling channels in a battery pack;

[0018] Figure 4 shows the encapsulant dispensers utilized in the method for casting cooling channels;

[0019] Figure 5 illustrates sectional view of a battery pack inserted with Teflon strip between each of the individual battery cells; and

[0020] Figure 6 illustrates sectional view of a battery pack with casted cooling channels between each of the individual battery cells.

[0021] Figure 7 illustrates graphical representation for dimensional changes of Teflon with respect to the temperature of the battery.

SUMMARY OF THE INVENTION
[0022] The present invention discloses a method which follows specific steps to cast or make cooling channels in battery packs. The casting steps include configuration of inlet and outlet at opposite sides of battery pack which is followed by filling the spaces between the individual cells of battery pack by inserting a polymer substrate strip from the inlet to the outlet. The polymer substrate strip may be a Teflon coated substrate (polytetrafluoroethylene), LDPE tube rolls and/or stack of wires. Then, one or more encapsulant like epoxy, silicone or polyurethane fillers etc. is poured to fill spaces in the battery pack which is not occupied with the polymer substrate strip. The encapsulant is allowed to cool or cure and then the polymer substrate strip is removed to define a pathway. The pathway allows coolant to flow between the inlet and the outlet which helps in removing the excess heat generated by the individual cells within a housing of the battery packs.

DETAILED DESCRIPTION OF EMBODIMENTS
[0023] The following detailed description and embodiments set forth herein below are merely exemplary out of the wide variety and arrangement of instructions which can be employed with the present invention. The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. All the features disclosed in this specification may be replaced by similar other or alternative features performing similar or same or equivalent purposes. Thus, unless expressly stated otherwise, they all are within the scope of the present invention.

[0024] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0025] The terms and words used in the following description and claims are not limited to the bibliographical meanings but are merely used to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention.

[0026] It is to be understood that the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.

[0027] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps, or components but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof.

[0028] Embodiments of the present invention relates to a method of casting cooling channels in battery packs or battery modules having multiple individual battery cells. In accordance with the disclosed embodiments, the invention provides a method to create a path or channels that may route a coolant through the battery packs. The present invention may be adapted to a wide range of settings and may be particularly well suited to battery packs used in electric or hybrid vehicles. Moreover, the casting method may be useful in other applications as well, such as power storage for alternative energy sources, portable battery modules, and back-up power supplies.

[0029] The term “batteries” as used herein should be understood in a broad sense encompassing replaceable electrical energy providing modules of any kind whether commonly denominated “batteries”, “storage cells,” or some other nomenclature. Further, the terms battery or battery modules or battery packs may be used interchangeably.

[0030] The cooling channels allow flow of coolant or fluid that removes the excess heat generated by the individual cells within a housing of the battery packs. The battery packs may include multiple individual cells within a housing, which may generate heat during normal operation. Figure 1 depicts a conventional battery pack system incorporated with metallic plates for flow of coolants. In these conventional battery pack systems, cooling plates passes through the battery pack and allows indirect contact of the coolant via thermal transfer material i.e. through the walls of the cooling plates. The incorporation of metallic cooling plates within battery packs make the battery system heavy.

[0031] The main aspect of the present invention is to provide a method for casting cooling channels that facilitates direct contact of coolant with the surface of each cell of the battery pack. The present invention is not limited to any battery system type, however in a preferred embodiment and as shown in figure 2, the battery system comprises of a plurality of cells (6) incorporated within a cell insert unit (5). The assembly of cell insert unit (5) along with the battery cells (6) are enclosed within two side clamps (1), at least one base plate (4), at least one CP assembly (8) and at least two dam/jig templates (2).

[0032] In accordance with an embodiment of the present invention and as shown in figure 3, the method for casting the cooling channels in battery packs and more specifically the cooling channels in between each of the individual battery cells comprising of an initial step of marking at least one inlet and a corresponding outlet at opposite sides of the battery pack along its breadth. Then a polymer substrate strip either having easily removable/moldable quality or dissolvable property is inserted from the inlet to the outlet in a continuous manner to fill the spaces between the individual cells. In an embodiment, the polymer substrate strip is selected from but not limited to a polytetrafluoroethylene (herein also termed as PTFE or Teflon). A single long strip of PTFE/ Teflon put along and between batteries into several manifolds in a zigzag fashion.

[0033] After complete insertion of the Teflon strip from inlet to outlet of the battery pack, an encapsulant is poured over it by means of plurality of encapsulant dispensers (3) as shown in figure 4. Figure 5 and figure 6 illustrates sectional view of a battery pack having plurality of cells aligned on a plastic cell tray using cell inserts, wherein an encapsulant dispenser (3) is attached to the inlet via aluminium side clamp (1) to pour encapsulant to the battery pack. Figure 5 illustrates battery pack with Teflon strip inserted from its inlet to outlet and between each of the individual battery cells. In a preferred embodiment, the encapsulant is selected from but not limited to epoxy (polyepoxides)/silicone/polyurethane fillers. In the following embodiments epoxy, silicone and polyurethane are interchangeably used. The epoxy from the encapsulant dispensers (3) fills all the remaining spaces of the battery pack which was not occupied with the manifolds of the Teflon strip (i.e. epoxy fills all the spaces except for the spaces occupied with Teflon). Then the epoxy is settling down and starts to get cure in the remaining spaces of the battery pack. When the epoxy gets settled down and cured in the space between the battery cells, the substrate strip is removed either side-ways or top-ways which fabricates the cooling channels within the battery pack. The casted cooling channel has defined pathway between the inlet and the outlet at opposite ends of the battery pack. Figure 6 illustrates battery pack with casted cooling channels between each of the individual battery cells which is generated by removing the teflon strip and pouring the encapsulant.

[0034] In a preferred embodiment of the present invention, Figure 7 illustrates graphical representation for dimensional changes of Teflon with respect to the temperature of the battery. The Teflon casting substrate used in casting the cooling channels of the battery overcomes the risk of cured epoxy (i.e. encapsulant) gripping the casting substrate, owing to shrinkage of Teflon upon curing. The Teflon casting substrate shrinks as the temperature of the battery drops, making it easier to remove the Teflon out of the casted cooling channel and from the grip of the cured epoxy. As per this embodiment, Teflon casting substrate rapidly shrinks below the temperature ranging from 25-28 degree Celsius in battery packs, except in the li-ion cells which have a process working range of 10-25 degree Celsius for avoiding premature aging.

[0035] In another embodiment, the polymer substrate strip is a triple layered Teflon strip with each layer having a thickness of 1 – 2 mm. Each of these layers are placed upon each other and inserted in the space between individual cells from the inlet to the outlet. Then again encapsulant is poured through dispenser and allowed to cool or cure before proceeding with the substrate removal stage. Once encapsulant is poured and cured, it shrinks arounds the substrate and thus, making it challenging to separate the encapsulant from the substrate. Therefore, in this embodiment, middle layer of teflon is removed first which is followed by removal of other two Teflon layers. This creates the cooling channels within the battery pack to allow coolant to flow.

[0036] In another embodiment, the space between individual cells from the inlet to the outlet is inserted with LDPE (low density polyethylene) Tube Rolls. The LDPE tube rolls have a wall thickness of 50 – 100 micron and are flat and elongated. These LDPE tube rolls are disposed between the cells as several manifolds from the inlet to the outlet placed on each of the breadth of the battery pack. Then the flat LDPE tube rolls are supplied with compressed air from one end of the LDPE tube, thus making the tubes swollen and occupying the hollow space between the individual cells of the battery pack. This is followed by pouring and curing of encapsulant over the swollen LDPE tube. After the curing of encapsulant, the compressed air pressure is released from the LDPE tubes and then the LDPE tubes are removed to fabricate cooling channels within the battery pack. In another embodiment, the plastic straw can be utilized in place of LDPE tubes to cast cooling channels. In this embodiment, the plastic straw can be either be removed to cast the open cooling channel or the plastic straw would remain inside through which the coolant liquid flows.

[0037] In another embodiment, the space between individual cells is inserted with stack of wire. A single long wire is stacked and placed between the battery cells as a manifold from inlet to outlet. This is followed by pouring and curing of encapsulant over the stack of wire. After the curing of encapsulant, the stack of wire is removed, thus creating the cooling channels within the battery pack.

[0038] The various embodiments of the present invention results in a battery pack system which provides following advantages:
• Temperature maintained between 25 to 30 degree during manufacturing of the battery pack;
• Reduces the part count drastically of the battery module;
• Reduces the overall weight of the battery module;
• Enables tighter packaging of battery modules, resulting in higher specific energy of the battery pack (battery holds more energy for given volume); and
• Simplified assembly of the battery module.

[0039] The foregoing examples and illustrative implementations of various embodiments have been provided merely for explanation and are in no way to be construed as limiting of the embodiments disclosed herein. While the embodiments have been described with reference to various illustrative implementations, drawings, and techniques, it is understood that the words, which have been used herein, are words of description and illustration, rather than words of limitation. Furthermore, although the embodiments have been described herein with reference to particular means, materials, techniques, and implementations, the embodiments are not intended to be limited to the particulars disclosed herein; rather, the embodiments extend to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims. It will be understood by those skilled in the art, having the benefit of the teachings of this specification, that the embodiments disclosed herein are capable of modifications and other embodiments may be effected and changes may be made thereto, without departing from the scope of the embodiments disclosed herein.