WO2025196770A1

WO2025196770A1 - A battery pack

Info

Publication number: WO2025196770A1
Application number: PCT/IN2024/051248
Authority: WO
Inventors: Santosh Bhagawat Gavhane; Kambi Reddy Poreddy; Manish Garg
Original assignee: TVS Motor Co Ltd
Current assignee: TVS Motor Co Ltd
Priority date: 2024-03-19
Filing date: 2024-07-15
Publication date: 2025-09-25
Anticipated expiration: 2026-09-19

Abstract

The present invention relates to a battery pack (100). The battery pack (100) includes a casing (101) having an interior space. A plurality of battery cells (120) disposed inside the interior space of the casing (101) and spaced apart from each other. A filler material (140) disposed in a space between the plurality of battery cells (120) and at least one fluid passage (130) is formed inside the interior space of the casing (101) and surrounding at least one portion of each of the plurality of battery cells (120), the at least one fluid passage (130) being adapted to receive a dielectric fluid (200) for regulating the temperature of the plurality of battery cells (120).

Description

TITLE OF INVENTION:

A BATTERY PACK

FIELD OF THE INVENTION

[001 ] The present invention relates to a battery pack and more particularly to a battery pack having an efficient cooling and thermal management system which enhances the safety and performance characteristics of the battery pack.

BACKGROUND OF THE INVENTION

[002] Batteries are increasingly being adopted across various sectors such as automotive, aerospace, consumer electronics, and renewable energy sources. Efforts within the industry are focused on improving battery capacity, with typical battery packs comprising multiple battery cells arranged in series and parallel configurations to meet specific voltage and current requirements.

[003] In electric vehicles, the battery pack serves as the primary energy source. During operation or charging, batteries generate significant heat, necessitating careful temperature control to prevent thermal runaway which is a catastrophic failure. To sustain safe and reliable battery operation, it's crucial to maintain temperatures within acceptable limits. Particularly during prolonged high-speed driving or high power operations of electric motors, where battery cells discharge at higher currents, rapid cooling becomes essential to prevent overheating. After discharge, battery cells should cool down to around 50°C before recharging to ensure immediate and safe charging. Uneven cell temperatures within the battery cells can lead to non- uniform discharge, causing voltage variations and reducing battery capacity utilization. To mitigate this, all battery cells must be kept within specified temperature limits.

[004] Existing thermal solutions provides battery packs with phase change materials (PCMs) for internal cooling purposes. However, PCMs suffer from slow solidification after melting due to their limited heat dissipation capabilities. This drawback renders them unsuitable for various applications requiring rapid recharging post-discharge. Further, it has been observed that operating the batteries at higher temperatures reduces the performance of the battery with reduced cell efficiency and shortens the overall life span of the battery pack. Furthermore, it also imposes serious safety concerns arising out of poor thermal management.

[005] With developments in areas of battery thermal management, solutions like active cooled technologies such as immersion cooling have been proposed in which a dielectric oil is made to circulate through all the battery cells. This solution improves the cooling performance significantly however if the battery pack is fully filled with the dielectric oil, the weight of the battery increases significantly which in turn negatively impacts the performance and efficiency of the electric vehicles. Further, existing systems fails in providing sufficient cooling capacity of the battery and rather increases complexity and weight to the battery pack which is undesirable. [006] It has been observed that increase in temperature within the battery cells while in use, limits functionalities such as rapid charging, consistent high speeds, immediate recharging after depletion, and impacts demanding driving scenarios like acceleration and uphill journeys. Also, owing to the excessive heat on terminals side of the battery cells, there remains risks of electrical short circuit between battery cells which poses a significant safety hazard.

[007] Thus, it is imperative to tackle these issues to improve the effectiveness, safety, and lifespan of battery packs across different uses, especially in electric vehicles. Therefore, there is a need for a battery pack that addresses the issues associated with existing battery pack systems.

SUMMARY OF THE INVENTION

[008] In an aspect of the present invention, a battery pack is disclosed. The battery pack includes a casing having an interior space. A plurality of battery cells are disposed inside the interior space of the casing and spaced apart from each other. A filler material is disposed in a space between the plurality of battery cells. The battery pack includes at least one fluid passage formed inside the interior space of the casing. The at least one fluid passage surrounds at least one portion of each of the plurality of battery cells. The at least one fluid passage is adapted to receive a dielectric fluid for regulating the temperature of the plurality of battery cells. [009] In an embodiment, the at least one portion surrounded by the at least one fluid passage is an upper portion or a lower portion of each of the plurality of battery cells.

[010] In an embodiment, at least one of the upper portion and the lower portion of the plurality of battery cells includes a terminal.

[011] In an embodiment, the filler material is configured to seal the space surrounding longitudinal sides of the plurality of battery cells.

[012] In an embodiment, the filler material is a lightweight and fire-retardant material.

[013] In an embodiment, the filler material is foam.

BRIEF DESCRIPTION OF THE DRAWINGS

[014] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

Figure 1 a illustrates a perspective view of a battery pack, in accordance with an embodiment of the present invention.

Figure 1 b is a side-cross sectional view of the battery pack illustrating the configuration of the battery cells immersed in dielectric liquid and surrounded with a filler material, in accordance with an embodiment of the present invention.

Figure 2 is a side-cross sectional view of the casing illustrating the configuration of the battery cells surrounded with a filler material and without the dielectric liquid, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[015] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder.

[016] The present invention provides a battery pack having an efficient cooling and thermal management system which enhances the safety and performance characteristics of the battery pack and reduces the weight of the battery pack.

[017] Figure 1 a illustrates a perspective view of a battery pack 100, in accordance with an embodiment of the present invention. Figure 1 b is a side-cross sectional view of the battery pack 100 illustrating the configuration of battery cells 120 immersed in dielectric liquid and surrounded with a filler material, in accordance with an embodiment of the present invention.

[018] As shown in Figures 1 a -1 b, the battery pack 100 includes a casing 101 being a sealed container and having an interior space. Depending upon the usage and requirements, the battery pack 100 includes a plurality of battery cells 120 disposed inside the interior space of the casing 101. The battery cells 120 includes, but not limited to, rechargeable Lithium-ion cylindrical cells, prismatic cells etc.

[019] The casing 101 is made of a durable and heat-resistant material such as plastic, metal, or composite materials. The casing 101 includes a base (B) and plurality of portions extending away from the base (B). The plurality of portions includes an upper portion 101 a, a lower portion 101d, side portions 101 b, 101 c extending between the upper portion 101 a and the lower portion 101 d. The battery pack includes 100 includes a cap portion 102 attached to the casing 101 in a fluid tight manner. The cap portion 102 includes a connector (C).

[020] Each battery cell 120 includes terminals i.e., a positive terminal and a negative terminal (not shown). The battery pack 100 includes a plurality of interconnectors (not shown). The plurality of interconnectors is configured to connect the plurality of battery cells 120 in series and/or parallel combination to obtain the desired current and/or voltage from the battery pack 100. The battery pack 100 includes a battery management system 150 disposed inside the interior space of the casing 101 .

[021 ] Referring to Figure 1 b, the plurality of battery cells 120 are disposed inside the interior space of the casing 101 . The plurality of battery cells 120 are disposed spaced apart from each other. A filler material 140 is disposed in a space between the plurality of battery cells 120 except the portions having the terminals. In a non-limiting example, the peripheral portions of each of the plurality of battery cells 120 are covered by the filler material 140.

[022] One or more fluid passages 130 are formed inside the interior space of the casing 101 depending upon the layout and orientation of the plurality of battery cells 120. In a non-limiting example, one of the fluid passage 130 is formed in a space available between the plurality of battery cells 120 and the adjacent inner sides of the casing 101 .

[023] In an embodiment, as shown in Figure 1 b, each of the upper side 120a and the lower side 120b of one of plurality of battery cells 120 is immersed inside the fluid passages 130 formed thereof. The fluid passages 130 surround portions of each of the plurality of battery cells 120 having the terminals. The fluid passage 130 is adapted to receive a dielectric fluid 200 for regulating the temperature of the plurality of battery cells 120. In a nonlimiting example, the dielectric fluid is a dielectric oil which is configured to absorb and dissipate the heat from the portions 120a, 120b of the plurality of battery cells 120.

[024] In an embodiment, the portions 120a, 120b of plurality of battery cells 120 are immersed in the dielectric fluid 200 and during operation of the battery pack 100, the dielectric fluid is circulated inside the interior space of the casing 101 through the fluid passages 130. In a non-limiting example, the fluid passages 130 of the battery pack 100 are connected to fluid circulating device including, but is not limited to, a fluid pump for circulating the dielectric fluid 200 inside the casing 101 .

[025] The casing 101 includes a fluid inlet (not shown) and a fluid outlet (not shown) for each of the fluid passage 130. During circulation, the dielectric fluid 200 enters inside the fluid passage 130 from the fluid inlet and exits from the fluid outlet.

[026] In a non-limiting example, an active circulation/flow of the dielectric fluid 200 is provided around the portions 120a, 120b of the each of the battery cells 120 where cooling is required as these portions 120a, 120b having terminals of the battery cells 120 are more heated during operation of the battery pack 100. The remaining volume of the internal space of the casing 101 filled with the filler material 140 where no circulation is required. In a non-limiting example, the remaining volume filled with the filler material having a specific gravity as 0.15 whereas actively cooled portion is filled with the dielectric liquid having the specific gravity as 0.9.

[027] Referring to Figure 2, a side-cross sectional view of the casing 101 illustrates the configuration of the plurality of battery cells 120 surrounded with the filler material 140 and without any dielectric liquid, in accordance with an embodiment of the present invention. The filler material 140 is configured to seal the space surrounding longitudinal sides 124 of the plurality of battery cells 120. In a non-limiting example, if the plurality of battery cells 120 are cylindrical in shape, the radial longitudinal sides of the battery cells 120 are surrounded with the filler material 140. The filler material 140 being a lightweight and fire-retardant material and being a foam made of polyurethane. In a further non-limiting example, the foam with a lightweight specific gravity 0.15 is used which is also a fire retardant. Foam helps to supress fire propagation from one of the plurality of battery cells to the adjacent battery cells 120 in case of the thermal runaway event.

[028] In an embodiment, a relatively low volume of the interior space of the casing 101 being occupied by the fluid passages 120 containing the dielectric fluid 200 (shown in Figure 1 b) in comparison to a larger volume of the interior space being occupied by the filler material 140. In a non-limiting example, the density of the filler material 140 is six times lower than the density of the dielectric fluid 200. Due to this configuration, the weight of the battery pack 100 is reduced in comparison to the conventional battery packs having the entire interior space occupied by the dielectric fluid 200.

[029] In an embodiment, the filler material 140 is provided in the internal space of the casing 101 in which the Battery management system 150 is disposed.

[030] Advantageously, the present invention provides a battery pack having an improved thermal management with reduction in weight. The present invention provides fluid passages through which dielectric liquid flows around intended portions I regions facilitating efficient heat dissipation which increases the efficiency of the battery cells. The present invention reduces the risks of overheating of the battery cells and prolongs the lifespan of the battery cells. The present invention utilizes a filler material being a lightweight material to fill the space between the plurality of cells of the battery packs and covering a major portion of the interior space of the battery pack which reduces the weight of the battery pack. The filler material is fire retardant material which increases the safety of the battery pack. The present invention increases the structural integrity of the battery pack. The present invention has a simple configuration of a battery pack which allows serviceability or repairment of the battery pack with ease.

[031 ] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

List of Reference Numerals

100 - Battery Pack

101 - Casing

101 a - Upper portion of the casing

101 b, 101 c - Side portions of the casing

101 d - Lower portion of the casing

102 - Cap portion of the casing

120 - Plurality of battery cells

120a - Upper side of the battery cell

120b - Lower side of the battery cell

124 - Longitudinal sides of the battery cell

130 - Fluid Passages

140 - Filler material 50 - Battery Management System

B - Base of the casing

C - Connector

Claims

We Claim:

1 . A battery pack (100) comprising: a casing (101 ) having an interior space; a plurality of battery cells (120) disposed inside the interior space of the casing (101 ) and spaced apart from each other; a filler material (140) disposed in a space between the plurality of battery cells (120); and at least one fluid passage (130) formed inside the interior space of the casing (101 ) and surrounding at least one portion of each of the plurality of battery cells (120), the at least one fluid passage (130) being adapted to receive a dielectric fluid (200) for regulating the temperature of the plurality of battery cells (120).

2. The battery pack (100) as claimed in claim 1 , wherein the at least one portion surrounded by the at least one fluid passage (130) being an upper portion (120a) or a lower portion (120b) of each of the plurality of battery cells (120),

3. The battery pack (100) as claimed in claim 2, wherein at least one of the upper portion (120a) and the lower portion (120b) of the plurality of battery cells (120) comprises a terminal.

4. The battery pack (100) as claimed in claim 1 , wherein the filler material (140) is configured to seal the space surrounding longitudinal sides (124) of the plurality of battery cells (120). 5. The battery pack (100) as claimed in claim 1 , wherein the filler material

(140) being a lightweight and fire-retardant material.

6. The battery pack (100) as claimed in claim 5, wherein the filler material (140) being foam.