Retrofittable Assembly for Battery Pack

Abstract

The subject matter described herein relates to a battery pack 400 including a retrofittable PCM injection unit 411 for injecting a phase change material (PCM) into the interior of the battery pack 400. The retrofittable PCM injection unit 411 includes a lid 401, a funnel 404, and a gasket 403. The lid 401 is disposed on a top cover 405 of the battery pack 400. The gasket 403 is provided between the lid 401 and the funnel 404, and the funnel 404 is inserted into a PCM fill port 406 of the battery pack 400. The subject matter provides an improved design of a battery pack that provides ease of use, high reliability, spill-free and safe injection of the phase change material (PCM) into the battery pack, thereby protecting electrical components from undesired damage.

Description

[Technical field]

[0001] The invention described herein relates generally to battery packs for vehicles. More particularly, the invention relates to a retrofittable PCM injection unit for injecting a phase change material (PCM) into a battery pack. [Background technology]

[0002] Typically, lithium-ion battery packs are used as power sources in electric and hybrid vehicles. The battery pack comprises multiple cylindrical cells interconnected in series and parallel arrangements to meet current, voltage, and capacity requirements. Charging and discharging of the multiple cells is monitored and controlled by a battery management system (BMS). The serial and parallel interconnection of multiple cylindrical cells poses various technical challenges. Charging and discharging at high currents can generate excessive heat, which can cause melting of components and imbalances between the multiple cylindrical cells, leading to fires in the battery pack. As lithium is a highly reactive element, lithium-ions are relatively unstable in nature, which poses safety challenges and requires special handling and operation requirements.

[0003] Generally, a battery pack generates a lot of heat during operation, which can cause the temperature of the battery pack to rise significantly. Eventually, the temperature can rise to a value where the battery pack can go into thermal runaway. A good battery pack design should be able to prevent thermal runaway. This design can be applied to pouch cells or prismatic cells depending on other requirements such as space, current, voltage, weight, and cost.

[0004] Conventionally, a thermal pad is used to ensure thermal management for a battery pack. The thermal pad is a heat dissipation pad used to control heat generated in the battery pack. Generally, the thermal pad is positioned between a battery module and a heat sink outside the battery pack. The thermal pad transfers heat generated inside the battery pack to the outside of the battery pack. When using a thermal pad, a special substrate is separately prepared for heat dissipation and insulation. The thermal pad is not advantageous in the case of cylindrical cells because the thermal pad does not provide proper contact between multiple cells. In addition, the thermal pad requires different layer thicknesses in different spaces. Therefore, the battery pack is not easy to use and assemble. In addition, the maximum heat resistance performance of the thermal pad is low. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention relates to a retrofittable PCM injection unit for injecting a phase change material (PCM) into a battery pack. [Means for solving the problem]

[0006] The present invention relates to a battery pack including a retrofittable assembly for injecting a phase change material (PCM). The retrofittable assembly includes a lid, a funnel, and a gasket. The lid is configured to hold the funnel. The lid is disposed on a top cover of the battery pack along with the gasket. The gasket is provided to prevent leakage of the PCM during injection of the PCM into the battery pack. The funnel is configured to be disposed on a bottom of the battery pack. The bottom includes a PCM fill port. The funnel is attached to the PCM fill port to allow flow of the PCM through the funnel and into the battery pack. The present invention will now be described in detail with reference to the accompanying drawings, in which the same reference numbers are used throughout to refer to like features and components, and in which: [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 illustrates a conventional battery pack according to existing technology. [Diagram 2] FIG. 1 is an exploded view of a conventional battery pack according to existing technology. [Diagram 3] FIG. 1 is an exploded view of a conventional battery pack according to existing technology. [Figure 4] FIG. 2 is an exploded view of a battery pack according to one embodiment of the present invention. [Figure 5a] FIG. 2 is a top view of a battery pack according to one embodiment of the present invention. [Figure 5b] FIG. 2 is a top view of a battery pack according to one embodiment of the present invention. [Figure 6] FIG. 1 illustrates a connection between a funnel and a PCM fill port according to one embodiment of the present invention. [Figure 7] FIG. 2 is an enlarged view of a funnel according to one embodiment of the present invention. [Figure 8] 1 illustrates a method of installing a retrofittable PCM injection unit inside a battery pack according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention relates generally to battery power sources, and more particularly to thermal management in such battery power systems. As used herein, the term "battery" is intended to include a variety of electrochemical forms of power generation that have as a common denominator chemical energy in the form of one or more chemical reactants stored within an enclosed space that react with each other or with external reactants in an electrochemical reaction to produce electrical power as desired.

[0009] Various uses of battery power sources have been well established. For example, it is well known and commonplace for multiple cells to be packaged together in parallel or series configurations to form battery modules or battery packs for use as power sources for personal electronic devices, such as mobile phones, laptop computers, or camcorders. Furthermore, the desired properties or characteristics of a battery power source, including, for example, the rechargeability of a particular battery power source, make such a battery power source a potential power source for vehicle propulsion, such as, for example, electric vehicles (EVs). In recent years, the concept and applications of battery power have been expanded to include "fuel cells" or "fuel cell batteries," in which a fuel cell reaction is utilized to generate power, similar to a traditional rechargeable battery, but where one of the reactants (the fuel) needs to be replenished from time to time.

[0010] In various such applications, a plurality of cells are typically packaged together in a preselected configuration (e.g., parallel or series) to form a battery module. A plurality of such battery modules may then be combined or joined to form various battery packs as known in the art. During charging and discharging of the cells in a battery module or battery pack, a large amount of heat is generated, which may significantly affect the resulting performance. Therefore, in order to maintain the desired or optimal performance of the cells, or of the resulting battery module or battery pack, it is important to maintain the temperature of the cells, battery module, or battery pack within a fairly narrow predetermined range.

[0011] In practice, temperature differences between individual cells may result from one or more of a variety of factors, including variations in ambient temperature, uneven impedance distribution between the cells, and differences in heat transfer efficiency between the cells.

[0012] Typically, differences in heat transfer efficiency between cells are primarily due to the cell pack configuration. For example, cell elements located in the center of the cell pack configuration may tend to accumulate heat, while cell elements located on the periphery of the cell pack configuration will generally tend to be cooled relatively easily or freely by heat transfer to the surrounding environment. Furthermore, such differences in heat transfer efficiency may result in further differences in impedance, such as an amplification of the capacity difference between the cells. Such capacity imbalances may cause or result in some cells being overcharged or overdischarged, which may further result in premature failure of the cell pack or certain cell elements of the cell pack. In particular, such failures may take the form of thermal runaway or reduced acceleration capabilities.

[0013] Thermal management systems based on active cooling (e.g., forced circulation of air, liquid, or other selected cooling medium) have been proposed for use in conjunction with such battery power systems, but the incorporation and use of such active cooling schemes can introduce a level of complexity into the design and / or operation of the power source that can impede or prevent more widespread use of such power sources.

[0014] Furthermore, the required or desired size of a battery power source is typically determined by its particular application. Thus, a particular anticipated or envisioned application of such a power source, such as powering an electric vehicle, may require the use of a power source having or consisting of physical dimensions significantly larger than commonly used or available power sources. As will be appreciated by those skilled in the art, thermal management in a power source system may become even more critical or important as the size of such cells, battery modules, or battery packs increases.

[0015] Typically, the structure of a lithium-ion battery consists of an outer metal casing and a plastic cell holder in which multiple cells are placed. A battery pack generally consists of multiple cells. The multiple cells are placed on the cell holder. The multiple cells located in the plastic cell holder are typically spaced apart by a distance of about 2 mm. Furthermore, there is a minimum gap of 1 mm to 5 mm between the outer casing and the plastic cell holder. Depending on the power requirements of the vehicle, the number of cells in the battery pack can be increased or decreased.

[0016] Lithium-ion battery packs are equipped with a battery management system (BMS) to prevent malfunctions occurring within the cells and to ensure that the series and parallel connected cells are operated within the desired current, voltage, and temperature ranges. Unfortunately, if the BMS cannot protect the lithium-ion cells, the cells may experience thermal runaway, resulting in fires and explosions. Also, if one cell in the series-parallel arrangement fails, the failure may spread to the other cells. Conventional battery structures are not equipped to protect against such failures.

[0017] Thermal management of lithium-ion battery packs is important to avoid thermal runaway. High internal battery pack temperatures can cause safety hazards and shorten the lifespan of the battery pack. According to known techniques, to ensure effective thermal management of lithium-ion battery packs, a phase change material (PCM) is filled between the cells inside the battery pack. The phase change material is a liquid dispensed gap filler material used to fill the space between the cells, and the heat generated during thermal runaway is absorbed by utilizing the heat absorption properties of the phase change process of the phase change material.

[0018] Generally, battery pack designers try to use thermal pads or phase change materials (PCMs) to effectively control the temperature in the battery pack. Various PCMs available in the market are used to suppress the temperature rise of the battery pack during charging and discharging operations. However, using PCMs in battery packs is more desirable than using thermal pads because PCMs have various advantages over thermal pads, such as lower cost. In addition, PCMs can flow into fine rough surfaces due to their liquid nature, and the better the flow, the lower the thermal interface impedance at each surface. In PCMs, the problem of air entrapment is negligible, whereas in thermal pads, it is a frequent problem. Battery packs using PCM materials provide greater design freedom.

[0019] Generally, a very common problem faced by battery pack designers is spillage around the battery pack and onto electrical components within the battery pack during filling of the PCM within the battery pack. Electrical parts that come into contact with the PCM may damage the electrical components in the long run. Thus, these electrical components suffer degradation over time due to spillage of the PCM during filling of the PCM inside the battery pack. Furthermore, filling the entire battery pack with PCM may result in increased weight and cost of the battery pack. Thus, when designing a battery, the PCM should be provided in such a way that allows maintaining the battery in the desired optimum temperature range, thus improving the range and lifespan of the battery pack.

[0020] To introduce the PCM into the battery pack by avoiding the problems mentioned above, a separate assembly is required to ensure uniform filling and avoidance of contact of the PCM with the battery management system (BMS) and PCB components of the battery pack. Furthermore, there is a need and demand for a power supply system and method of operation that desirably avoids the potential complications and complications mentioned above. Furthermore, there is a need and demand for a well-designed thermal management system that can better ensure one or more of the performance, safety, or capacity of the associated power supply.

[0021] In view of the above, it is an object of the present invention to provide an improved design of a battery pack that allows for ease of use, reliability, spill-free and safe injection of a phase change material (PCM) into the battery pack, thereby protecting the electrical components inside the battery pack from undesired damage during refurbishment. According to another object of the present invention, the solution needs to be retrofittable to conventional battery packs to allow for easy spill-free supply of the PCM. The PCM is disposed along a thermal pathway within the battery cell assembly that transfers heat generated by the battery cells during operation away from the battery cells.

[0022] In the present invention, a battery pack includes a battery module, a battery cell assembly that is a component of the battery module, and a battery cell of the battery cell assembly that includes a plurality of battery cells. In one embodiment, each of the plurality of battery cells is configured to generate heat during operation. Furthermore, the battery cell assembly includes a phase change material (PCM) disposed along a thermal path within the battery cell assembly that transfers heat generated by each of the plurality of battery cells during operation away from the plurality of battery cells. Furthermore, the PCM is configured to affect a phase change by absorbing heat generated by the plurality of battery cells. The PCM material is expected to significantly reduce the temperature during battery operation and prevent thermal runaway by being able to hold more thermal energy (high latent heat capacity material). This increases the operating temperature band of the battery pack, thus improving the safety and range of the vehicle.

[0023] In one embodiment, a known amount of phase change material is preheated to a temperature where it becomes completely liquid. This amount depends on the design of the battery pack, which is determined by the type of cells, the number of cells, and other design parameters. Based on the heat generation of the cells, the volume of PCM required is determined and can be increased or decreased accordingly. This liquid PCM is then injected into the battery pack via a retrofittable PCM injection unit, which is provided on the battery pack and allows filling the space between the cylindrical / pouch cells.

[0024] According to one aspect of the present invention, a PCM injection unit includes a lid, a funnel, and a gasket, and the PCM injection unit is retrofittable onto a conventional battery pack.

[0025] According to another aspect of the invention, the lid of the PCM injection unit is configured to hold a funnel.

[0026] According to yet another aspect of the present invention, a lid is disposed on the top cover of the battery pack along with a gasket.

[0027] According to another aspect of the present invention, a gasket is provided to avoid leakage during injection of the PCM material into the battery pack.

[0028] According to yet another aspect of the invention, the funnel is configured to be placed on the bottom of the battery pack where a PCM fill port is available.

[0029] According to yet another aspect of the invention, the base includes a PCM fill port, and in one embodiment, a funnel is attached to the PCM fill port to direct the flow of the PCM through the funnel and into the thermal path of the battery pack.

[0030] According to yet another aspect of the present invention, the PCM is gradually filled into the battery pack through a funnel to prevent the formation of air bubbles inside the battery pack.

[0031] According to one aspect of the invention, the funnel is sloped at an obtuse angle to prevent clogging of the PCM inside the funnel.

[0032] According to one aspect of the invention, the PCM injection unit is removably attached to the battery pack.

[0033] According to one aspect of the invention, the PCM is a hydrocarbon material having a phase transition temperature in the range of 30°C to 70°C.

[0034] According to one aspect of the invention, the lid is made from metal and the bottom is made from plastic.

[0035] According to one aspect of the invention, the PCM is separately preheated to a predetermined temperature prior to injection into the battery pack, where the predetermined temperature is 5° C.-10° C. higher than the phase transition temperature of the PCM but less than 85° C., the predetermined temperature range being determined by the design of the battery pack.

[0036] The summary presented above describes the basic features of the present invention and is not intended to limit the scope of the present invention. The characteristics and other features of the present subject matter will become more apparent from the following description taken in conjunction with the accompanying drawings.

[0037] Next, with reference to the attached drawings, exemplary embodiments of the retrofittable PCM injection unit for a battery pack according to the present invention and its structural features will be described in detail. From the following description set forth below, various aspects of various embodiments of the present invention will become apparent. More precisely, the following description sets forth preferred examples for realizing the exemplary embodiments of the present invention. It should also be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting.

[0038] In the following paragraphs, in combination with the drawings, the present invention together with all its attendant embodiments and other advantages thereof will be explained in more detail.

[0039] FIG. 1 shows a conventional battery pack 100. Typically, the battery pack 100 includes a top cover 104, a bottom cover 107, and an aluminum casing 106. The top cover 104 has a lid 103. In one embodiment, the metal used in the lid 103 is aluminum. A lid holder 102 is further provided on the top cover 104. The lid 103 is provided for injecting a phase change material into the battery pack 100. The lid 103 is fixed on the top cover 104 with the aid of a fastener. A safety valve 101 is further provided on the top cover 104.

[0040] 2 shows an exploded view of a conventional battery pack 100 without the battery cell assemblies 111. The battery pack 100 includes a top cover 104, an interconnector, and an interconnector damper, along with a plastic cell holder 105, an aluminum casing 106, and a bottom cover 107.

[0041] FIG. 3 shows an exploded view of a conventional battery pack 100. A top cover 104 has a lid 103. A PCM fill port 108 is provided on a bottom member 109. The bottom member 109 further provides a space for holding a battery management system (BMS) (not numbered). The bottom member 109 can also hold a PCB 110. The PCB 110 is used to sense the temperature and voltage inside the battery pack 100. A battery cell assembly 111 including a cell holder 105 capable of holding a number of battery cells is further provided inside the aluminum casing 106. A bottom cover 107 is provided to seal the battery pack from the bottom. The battery pack has a lid 103 through which the PCM 502 can be poured, which causes spillage. Spillage of the PCM 502 material may cause damage to electrical components located nearby inside the battery pack 100. According to the present invention as shown in FIG. 4, a three-component retrofittable PCM injection unit 411 is provided for gradually injecting PCM into the interior of a battery pack, thereby avoiding the formation of air bubbles inside the battery pack and spillage of PCM onto nearby electrical components.

[0042] FIG. 4 shows an exploded view of a battery pack 400 in one embodiment of the present invention. For ease of explanation, FIG. 4 and FIG. 7 are discussed together. According to one embodiment, the battery pack 400 comprises a battery module 409, which comprises one or more of the battery cell assembly 111, an interconnector (not numbered), and a damper (not shown). The top cover 405 comprises a retrofittable PCM injection unit 411, which comprises a lid 401, which has a slot 402 for fluidly mounting a funnel 404. In one embodiment, the lid 401 is made of aluminum. Thus, the three-component retrofittable PCM injection unit 411 of the present invention can avoid spillage onto electrical components, thereby avoiding undesired contact with the PCM 502. The retrofittable PCM injection unit 411 has a lid 401 combined with a gasket 403. The lid 401 and gasket 403 are both removably mounted in a slot 405' provided for the lid 401 in the top cover 405. A first end 404A of a funnel 404 having an engagement portion 4041 is mounted on the lid 401, and a second end 404B of the funnel 404 is inserted into a PCM fill port 406 in the plastic bottom 407 as shown in FIG. 6, which shows a detailed view of the lid 401, gasket 403 and funnel 404 coupled together. The funnel 404 is configured with an engagement portion 4041 having an opening that fluidly engages with the fill slot 402, followed downstream by a first conduit portion 4042 that extends at a first angle x (as shown in FIG. 7) relative to an inlet axis AA' of the engagement portion 4041. According to one embodiment, the angle x can be 180 degrees, implying that the first conduit section 4042 is substantially parallel to the inlet axis AA'. Additionally, the funnel 404 comprises a downstream second conduit section 4043 oriented at a second angle y (as shown in FIG. 7) relative to the inlet axis AA'. According to one aspect of the invention, the second conduit section 4043 forms an obtuse angle y with respect to the inlet axis AA'.The obtuse angle y greater than 90° allows for smooth flow of the PCM502 material during filling and avoids undesirable clogging within the funnel 404. According to an alternative embodiment, one or more of the engagement portion 4041, the first conduit portion 4042, and the second conduit portion 4043 may be separately or integrally formed.

[0043] 5a and 5b show top views of a battery pack 400. In one embodiment of the present invention, the battery pack 400 comprises a plurality of cells 501. The plurality of cells 501 may be cylindrical cells or pouch cells. The gaps between the cells 501 are filled with PCM 502 material to absorb heat generated in the cells during operation of the battery. A known amount of PCM 502 is separately preheated to a predetermined temperature. The predetermined temperature is 5°C to 10°C higher than the phase transition temperature of the PCM, but less than 85°C. The amount of PCM 502 material injected into the battery pack 400 is determined by the design of the battery pack. The design of the battery pack is further determined by the type of cells and other design parameters. Based on the heat generated from the cells 501, the required volume of PCM 502 inside the battery pack 400 can be determined and increased or decreased accordingly. The PCM 502 is then allowed to be injected into the battery pack 400 and fill the spaces between the cylindrical or pouch cells 501. The PCM 502 absorbs the heat generated by the cells 501, thus increasing the operating range of the battery pack 400. The PCM 502 prevents the battery pack 400 from exceeding its operating temperature, thus improving safety with respect to drastic temperature increases in the battery pack 400.

[0044] Due to the lower temperature within the battery pack 400, the PCM502 naturally cools and solidifies after filling the voids within the pack. The typical period for the PCM502 to solidify is about 30 minutes to 1 hour at ambient temperatures ranging between 30° C. to 35° C. The PCM502 has a high latent heat and therefore absorbs the heat generated within the cells 501 during charging and discharging operations, thus the PCM502 material helps to significantly reduce the temperature during battery operation, improving the life and range of the pack 400.

[0045] FIG. 6 shows the connection between the funnel 404 and the PCM filling port 406 in an embodiment of the present invention. The retrofittable PCM injection unit 411 includes a lid 401 combined with a gasket 403. The retrofittable PCM injection unit 411 is placed in a slot 405' provided in the top cover 405. The funnel 404 is inserted into the PCM injection port 406 of the plastic bottom 407. The PCM injection port 406 then pumps the PCM 502 toward the thermal path inside the battery pack 400, where the PCM 502 fills the gaps inside the cells 501. The retrofittable PCM injection unit 411 is removably attached to the battery pack 400. This avoids the PCM spilling onto nearby electrical components, thereby improving the reliability, safety, and ease of use or replacement of the PCM 502. Injecting the PCM slowly is also useful for avoiding the formation of air bubbles inside the battery pack 400. This is also useful for preventing air entrapment problems inside the battery pack.

[0046] 7 shows a close-up view of the funnel 404 in one embodiment of the invention, which is sloped at an obtuse angle to prevent PCM from clogging inside the funnel 404. According to one embodiment, angle x and angle y should be greater than 90 degrees and less than 180 degrees.

[0047] 8 illustrates a method of mounting a retrofittable PCM injection unit 411 in a battery pack 400. According to one embodiment of the present invention, the retrofittable injection unit 411 includes a lid 401, a gasket 403, and a funnel 404. The lid 401 is mounted on the top cover 405 of the battery pack 400 with the aid of adhesive or fasteners (step 801). Furthermore, a gasket 403 is provided between the lid 401 and the funnel 404 to prevent leakage during injection of PCM (step 802). Furthermore, the funnel 404 of the retrofittable PCM injection unit 411 is mounted on the PCM filling port 406 (step 803).

[0048] Numerous modifications and variations of the present invention are possible in light of the above disclosure, and therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described. [Explanation of symbols]

[0049] 100 Battery Packs 101 Safety valve 102 Holder 103 Lid 104 Top cover 105 Cell Holder 106 Outer casing 107 Lower cover 108 PCM filling port 109 Bottom member 110 PCB 111 Battery Cell Assembly 400 Battery Pack 401 Lid 402 Slot to hold funnels 403 Gasket 404 Funnel 404A First End 404B Second end 4041 Engagement part 4042 First Conduit 4043 Second Conduit 405 Top Cover 405' Slot 406 PCM filling port 407 Bottom 408 PCB 409 Battery Module 410 Outer casing 411 Retrofittable PCM Injection Unit 501 Cell 502 PCM supplied to gap

Claims

1. A battery pack (400), a battery module (409) comprising one or more battery cell assemblies (111), an interconnector, and a damper; The battery cell assembly (111) includes a plurality of battery cells (501); a phase change material (PCM) (502) capable of transferring heat generated by the plurality of battery cells (501) during operation away from the plurality of battery cells (501); Equipped with The battery pack (400) is configured with a retrofittable PCM injection unit (411), which enables safe injection of the phase change material (PCM) (502) into the battery module (409) without spillage.

2. 2. The battery pack (400) of claim 1, wherein the retrofittable PCM injection unit (411) comprises a lid (401), a funnel (404), and a gasket (403), and the lid (401) is provided with a PCM filling slot (402).

3. The battery pack (400) comprises a top cover (405), the top cover (405) having a slot (405'); The lid (401) is configured to hold the funnel (404); The lid (401) is detachably mounted in the slot (405') together with the gasket (403); 3. The battery pack (400) of claim 2, wherein the gasket (403) is provided to prevent leakage of the phase change material (PCM) (502) during injection.

4. a second end (404B) of the funnel (404) inserted into a PCM fill port (406); The battery pack (400) of claim 3, wherein the PCM fill port (406) is provided on a bottom member (407) of the battery pack (400).

5. the funnel (404) is configured with an engagement portion (4041) at a first end (404A) of the funnel (404); said engagement portion (4041) having an inlet axis AA', a first conduit portion (4042), and a second conduit portion (4043); 3. The battery pack (400) of claim 2, wherein the second conduit portion (4043) forms a second end (404B) of the funnel (404).

6. the engaging portion (4041) has an opening that fluidly engages the PCM fill slot (402); the first conduit portion (4042) is provided downstream of the engagement portion (4041); said first conduit portion (4042) extends at a first angle (x); 6. The battery pack (400) of claim 5, wherein the first angle (x) is taken with respect to the inlet axis AA' of the engaging portion (4041).

7. the angle (x) is 180 degrees, which indicates that the first conduit portion (4042) is substantially parallel to the inlet axis AA'; The battery pack (400) of claim 6.

8. The second conduit section (4043) is provided downstream of the first conduit section (4042), said second conduit portion (4043) is oriented at a second angle (y); 7. The battery pack (400) of claim 6, wherein the second angle (y) is taken with respect to the inlet axis AA'.

9. 9. The battery pack (400) of claim 8, wherein the second conduit portion (4043) forms an obtuse angle (y) with respect to the inlet axis AA'.

10. 6. The battery pack (400) of claim 5, wherein the engagement portion (4041), the first conduit portion (4042), and the second conduit portion (4043) are formed separately or integrally.

11. The battery pack (400) of any preceding claim, wherein the phase change material (PCM) (502) is a hydrocarbon material having a phase transition temperature in the range of 30°C to 70°C.

12. The battery pack (400) of claim 2, wherein the lid (401) is made of metal or plastic.

13. The phase change material (PCM) (502) is separately preheated to a predetermined temperature before injecting the phase change material PCM (502) into the battery pack (400); 2. The battery pack (400) of claim 1, wherein the predetermined temperature is 5-10°C higher than the phase transition temperature of the phase change material (PCM) (502), but less than 85°C.

14. 1. A method for transferring a phase change material (PCM) into a battery pack (400), comprising: a step of attaching a retrofittable PCM injection unit (411) to a battery pack (400), the retrofittable PCM injection unit (411) including a lid (401), a funnel (404), and a gasket (403), and removably attaching the lid (401) to an upper cover of the battery pack (400); a step of detachably attaching a gasket (403) between the lid (401) and the funnel (404) to prevent leakage when injecting the phase change material (PCM) (502) into the battery pack (400); inserting the funnel (404) into the PCM fill port (406) to facilitate the flow of the phase change material (PCM) (502) through the funnel (404) and into the battery pack (400), the PCM fill port (406) being located on a bottom member (407) of the battery pack (400); A method comprising:

15. The method of claim 14, wherein the phase change material PCM (502) is a hydrocarbon material having a phase transition temperature in the range of 30°C to 70°C.

16. The method of claim 15, wherein preheating the phase change material (PCM) to a predetermined temperature is performed prior to injecting the phase change material (PCM) into the battery pack (400); The method of claim 14, wherein the predetermined temperature is 5-10°C higher than the phase transition temperature of the phase change material PCM (502), but less than 85°C.

Images