Battery immersion cooling device and battery immersion cooling method

Abstract

The present disclosure relates to a battery immersion cooling device and a battery immersion cooling method. The battery immersion cooling device according to an embodiment of the present disclosure includes a module case accommodating a plurality of battery cells and containing immersion refrigerant for immersion cooling of the battery cells, and a cooling unit provided at one side of the module case and circulating circulation refrigerant, the cooling unit including a circulation refrigerant inflow port and a circulation refrigerant outflow port, the circulation refrigerant exchanging heat with the immersion refrigerant while circulating through a flow path of the cooling unit, thereby being capable of indirectly cooling the battery cells.

Description

Technical Field

[0001] This disclosure relates to battery cooling technology applied to energy storage systems (ESS), and more specifically, to a battery immersion cooling device and method utilizing immersion cooling and an external cooling unit. Background Technology

[0002] Energy storage systems (ESS) are widely used in various fields such as regulating electricity demand, storing renewable energy, and improving power quality. In particular, the application of ESS based on lithium-ion batteries is increasing rapidly.

[0003] However, due to their high energy density, lithium-ion batteries pose a risk of thermal runaway, which can lead to a rapid rise in temperature and fire. Therefore, the importance of highly reliable cooling technologies is becoming increasingly apparent.

[0004] Recently, it has been pointed out that a large part of the causes of ESS fire accidents are thermal runaway caused by heat transfer between cells. Therefore, it is necessary to rapidly control the heat generation of a single cell to prevent it from spreading to the cooling structure of adjacent cells. Summary of the Invention

[0005] Technical problems to be solved

[0006] According to embodiments of this disclosure, a battery immersion cooling device and a battery immersion cooling method are intended to be provided, which can effectively control heat diffusion by performing indirect heat exchange between the immersion refrigerant used for immersion cooling of the battery cell and the circulating refrigerant circulating through the cooling unit.

[0007] Technical solution

[0008] According to an embodiment of the present disclosure, a battery immersion cooling device includes: a module housing containing a plurality of battery cells and containing an immersion refrigerant immersing the battery cells; and a cooling unit disposed on at least one side of the module housing and for circulating refrigerant, the cooling unit including a circulating refrigerant inlet and a circulating refrigerant outlet, wherein the circulating refrigerant can indirectly cool the battery cells by exchanging heat with the immersion refrigerant while circulating through the flow channel of the cooling unit.

[0009] In one embodiment, the cooling unit may be disposed in at least one of the upper, lower and side portions of the module housing.

[0010] In one embodiment, the cooling unit may include a cooling plate having multiple internal cooling channels.

[0011] In one embodiment, the cooling unit includes a serpentine tube assembly having a plurality of repeatedly arranged cooling tubes aligned in a manner corresponding to thermal barrier barriers disposed between adjacent cells in the battery cell, thereby preventing thermal runaway, for example, by concentrating heat removal in the cell boundary region.

[0012] In one embodiment, the serpentine tube assembly may be positioned at a predetermined distance from the upper end of the battery cell, such that it provides an exhaust path in the event of thermal runaway.

[0013] In one embodiment, the cooling unit is a tubular structure comprising multiple straight or bent cooling pipes.

[0014] In one embodiment, the circulating refrigerant can flow in a single direction from the circulating refrigerant inlet to the circulating refrigerant outlet.

[0015] In one embodiment, the cooling unit may include branch cooling pipes and connecting cooling pipes connected to the branch cooling pipes, wherein the connecting cooling pipes are arranged in parallel or in series.

[0016] In one embodiment, the flow channels of the cooling unit can be connected in parallel or in series in the form of a single loop or multiple loops.

[0017] In one embodiment, the circulating refrigerant may include one or more of the following: propylene glycol / aqueous solution (e.g., PG25 or a 25% propylene glycol / water mixture), mineral oil, synthetic oils, natural esters, synthetic esters, fluorocarbon, perfluorinated fluids (e.g., Fluorinert), hydrofluoroether (HFE) fluids (e.g., Novec), and inert perfluoropolyether (PFPE).

[0018] In one embodiment, the cooling unit may be laminated with, for example, a metal heat sink for instantaneous heat dissipation or a phase change material (PCM) for absorbing latent heat.

[0019] The battery immersion cooling method according to embodiments of the present disclosure may include: a step of preparing a module housing to accommodate multiple battery cells; a step of filling the module housing with an immersion refrigerant to immerse the battery cells; a step of providing a cooling unit on at least one side of the module housing having a circulating refrigerant inlet and a circulating refrigerant outlet and forming a flow channel between the circulating refrigerant inlet and the circulating refrigerant outlet; a step of circulating the circulating refrigerant from the circulating refrigerant inlet through the flow channel of the cooling unit to the circulating refrigerant outlet; and a step of indirectly cooling the battery cells by exchanging heat between the circulating refrigerant circulating through the flow channel and the immersion refrigerant.

[0020] In one embodiment, the cooling unit may be disposed in at least one of the upper, lower and side portions of the module housing.

[0021] In one embodiment, the cooling unit may include a cooling plate having multiple internal cooling channels.

[0022] In one embodiment, the cooling unit includes a serpentine tube assembly having a plurality of cooling tubes arranged in a repeating pattern. The cooling tubes can be aligned in a manner corresponding to thermal barrier barriers disposed between adjacent cells in the battery cell, thereby preventing thermal runaway, for example, by concentrating heat removal in the cell boundary region.

[0023] In one embodiment, the serpentine tube assembly may be configured to be spaced at a predetermined distance from the upper end of the battery cell (depending on the expected gas emission and the shape of the battery cell, for example, between 5 mm and 50 mm, preferably between 10 mm and 30 mm) to avoid obstructing upward gas flow in the event of thermal runaway.

[0024] In one embodiment, the cooling unit may be a tubular structure comprising multiple straight or bent cooling pipes.

[0025] In one embodiment, the circulating refrigerant can flow in a single direction from the circulating refrigerant inlet to the circulating refrigerant outlet.

[0026] In one embodiment, the cooling unit includes branch cooling pipes and connecting cooling pipes that connect them, and the connecting cooling pipes may be arranged in parallel or in series.

[0027] In one embodiment, the cooling unit may be laminated with a metal heat sink for instantaneous heat dissipation or a phase change material (PCM) for absorbing latent heat.

[0028] Technical effect

[0029] According to one embodiment of this disclosure, heat diffusion can be effectively blocked by applying an immersion cooling structure that utilizes an immersion cooling structure that uses an immersion refrigerant and an indirect cooling structure that uses a cooling unit that circulates a circulating refrigerant. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a battery immersion cooling device with a cooling plate according to an embodiment of the present disclosure. Figure 1 The cooling plate is shown mounted on the upper part of the module housing.

[0031] Figure 2 This is a schematic diagram of an embodiment of a battery immersion cooling device with a cooling plate according to an embodiment of the present disclosure, wherein the cooling plate is shown mounted on the lower part of the module housing.

[0032] Figure 3 This is a schematic diagram of an embodiment of a battery immersion cooling device with cooling plates according to embodiments of the present disclosure, wherein the cooling plates are shown mounted on the upper and lower parts of the module housing.

[0033] Figure 4 This is a schematic diagram of an embodiment of a battery immersion cooling device with a cooling plate according to an embodiment of the present disclosure, wherein the cooling plate is shown mounted on the side of the module housing.

[0034] Figure 5 This is a schematic diagram of a battery immersion cooling device with a cooling unit having a serpentine tube assembly according to an embodiment of the present disclosure.

[0035] Figure 6 This is a schematic diagram showing the alignment between the serpentine tube assembly and the thermal barrier disposed between the battery cells according to an embodiment of the present disclosure.

[0036] Figure 7 This is a schematic diagram of a battery immersion cooling device with a tubular cooling unit according to an embodiment of the present disclosure.

[0037] Figure 8 This is a flowchart of a battery immersion cooling method according to an embodiment of the present disclosure. Detailed Implementation

[0038] The present disclosure will now be described in detail with reference to the accompanying drawings. However, this is merely exemplary and the present disclosure is not limited to the specific embodiments described herein.

[0039] Although terms such as "first," "second," etc., are used to describe various elements, components, and / or parts, these elements, components, and / or parts are clearly not limited by these terms. These terms are used only to distinguish one element, component, or part from other elements, components, or parts. Therefore, it is natural that the first element, first component, or first part mentioned below can also be a second element, second component, or second part within the technical concept of this disclosure.

[0040] The terminology used in this specification is for illustrative purposes and is not intended to limit the scope of this disclosure. In this specification, singular forms include plural forms as well, unless otherwise specified herein. The expressions “comprises” and / or “made of” as used in this specification are to be construed as not excluding the presence or addition of one or more other components, steps, operations, and / or elements besides those mentioned.

[0041] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in the sense that would be commonly understood by one of ordinary skill in the art to which this disclosure pertains. Furthermore, unless explicitly defined otherwise, terms defined in general dictionaries should not be idealized or over-interpreted.

[0042] A dual-cooling system is provided and described, combining direct immersion cooling with indirect heat exchange via a separate cooling unit. This design effectively prevents thermal runaway from initial hot spots to adjacent cells, which is crucial for lithium-ion battery applications. This is because lithium-ion batteries typically have high energy densities, thus posing a risk of rapid temperature rise and fire. The immersion refrigerant absorbs heat through direct contact with the cells, mitigating localized heat generation and maintaining overall temperature uniformity. The overall design reduces temperature deviations between cells and improves the uniformity of cooling efficiency during normal operation and initial heat generation. The inclusion of a cooling plate promotes uniform refrigerant circulation and efficient heat exchange, thereby improving thermal response speed. Furthermore, the circulating refrigerant within the cooling unit continuously removes heat from the immersion refrigerant, preventing heat buildup within the module housing. This dual-path structure ensures that even if one cooling mechanism is temporarily overloaded in the event of thermal runaway, the other mechanism continues to operate, providing fail-safe thermal management.

[0043] Unlike existing air-cooled systems limited by their low thermal transfer coefficients or existing liquid cooling plate systems that only cool the bottom surface of the battery cell, this disclosure cools the entire surface of the battery cell by immersion while maintaining continuous heat removal through an external cooling device. This provides a more uniform cell temperature and a faster thermal response compared to single-mode cooling methods.

[0044] Figures 1 to 4This is a schematic diagram of a battery immersion cooling device having a cooling layer or cooling plate according to an embodiment of the present disclosure. Figure 5 This is a schematic diagram of a battery immersion cooling device with a cooling unit having a serpentine tube assembly according to an embodiment of the present disclosure. Figure 6 This is a schematic diagram showing the alignment between the cooling unit of the serpentine tube assembly and the cell thermal barrier according to an embodiment of the present disclosure. Figure 7 This is a schematic diagram of a battery immersion cooling device with a tubular cooling unit according to an embodiment of the present disclosure.

[0045] As shown in the figure, the battery immersion cooling device according to an embodiment of the present disclosure includes: a module housing 100, which houses a plurality of battery cells 10 and contains an immersion refrigerant for immersion cooling of the battery cells 10; and a cooling unit 200 disposed on one side of the module housing 100 and for circulating refrigerant. The immersion refrigerant can completely immerse the battery cells 10. Alternatively, the immersion refrigerant can only immerse a portion of the battery cells 10. For example, the lower part of the battery cell 10 can be immersed in the immersion refrigerant, while the remaining part can be exposed above the immersion refrigerant. The cooling unit 200 includes a circulating refrigerant inlet 210 and a circulating refrigerant outlet 220. The circulating refrigerant exchanges heat with the immersion refrigerant while circulating through the flow channels of the cooling unit 200, thereby enabling indirect cooling of the battery cells 10.

[0046] As used in this disclosure, "indirect cooling" refers to cooling the battery cell without direct contact between the circulating refrigerant and the cell itself. That is, the circulating refrigerant exchanges heat with the submerged refrigerant, while the submerged refrigerant cools the cell through direct contact.

[0047] This disclosure pertains to immersion cooling of the battery cell 10, which may include a module housing 100 and a cooling unit 200.

[0048] According to an embodiment of this disclosure, the module housing 100 accommodates a plurality of battery cells 10 and contains an immersion coolant inside. The immersion coolant is a fluid that cools the battery cells 10 by directly immersing them. The choice of which fluid to use may depend on a variety of factors, including the operating temperature range, required insulation strength, viscosity, cost, and environmental considerations. Insulating fluids, such as mineral oil (e.g., transformer oil), propylene glycol / aqueous solution (e.g., PG25), synthetic oil fluids, natural ester fluids, synthetic ester fluids, fluorocarbon fluids, perfluorinated fluids, hydrofluoroether (HFE) fluids, and perfluoropolyether (PFPE) fluids, can be used for immersion cooling. As synthetic oils, poly-alpha-olefin (PAO) and synthetic esters may be included. As natural esters and synthetic esters, Cargill's Priolube EF system may be included. Fluorocarbon and perfluorinated fluids include Fluorinert fluids, and HFE fluids can include Novec fluids, such as Novec 649 and Novec 7100. Additionally, PFPE fluids can include PFPE products. This insulating, impregnated refrigerant exhibits excellent insulation, flame retardancy, and chemical stability, and demonstrates high reliability at high temperatures.

[0049] The battery cell 10 can be configured as one or a combination of pouch, prismatic, and cylindrical types, and the module housing 100 can accommodate these various shaped battery cells. The immersed refrigerant absorbs heat by directly contacting these battery cells, thereby alleviating localized heating and maintaining a uniform overall temperature distribution.

[0050] According to an embodiment of this disclosure, the cooling unit 200 is disposed on one side of the module housing 100 and is a structure for circulating refrigerant. Here, "one side" can refer to at least one of the upper part, lower part, and side part of the module housing 100. For example, when the cooling unit 200 is disposed on the upper part of the module housing 100, the cooling unit 200 can be disposed in the upper region or on the upper surface of the module housing 100. Similarly, when the cooling unit 200 is disposed on the lower part of the module housing 100, the cooling unit 200 can be disposed in the lower region or on the bottom surface of the module housing 100. When the cooling unit 200 is disposed on the side part of the module housing 100, the cooling unit 200 can be disposed in the side region or on the side surface of the module housing 100. Depending on the cooling purpose and system design, the cooling unit 200 can be disposed in more than one direction.

[0051] According to one embodiment, the cooling unit 200 has flow channels through which circulating refrigerant can circulate from the circulating refrigerant inlet 210 to the circulating refrigerant outlet 220. The circulating refrigerant exchanges heat with the immersed refrigerant through the outer wall of the cooling unit 200, thereby indirectly cooling the battery cell 10.

[0052] This indirect heat exchange method can ensure cooling performance while maintaining electrical insulation, thereby improving system safety and cooling reliability.

[0053] According to one embodiment of the present disclosure, the cooling unit 200 can be disposed at at least one of the upper, lower and side portions of the module housing 100, thereby enabling it to be applicable to various types of ESS or battery packs.

[0054] According to one embodiment, a module housing 100 accommodates multiple battery cells 10 and includes space for immersion cooling of the battery cells 10 by providing direct immersion cooling of the refrigerant. The module housing 100 can be made of stainless steel, tempered glass, acrylic resin, engineering plastics, or aluminum alloy. Stainless steel is the most commonly used material due to its high resistance to cooling oil corrosion and robust construction. Tempered glass and acrylic resin allow direct observation of the internal cooling oil flow or bubble formation, making them suitable for use when visual monitoring is required, but may require reinforcement. Engineering plastics, including PTFE (Teflon) and PEEK, are chemically almost inert, thus reducing the likelihood of cooling oil contamination. However, they are more expensive and may require reinforcement. Aluminum alloys have good thermal conductivity, allowing for some heat dissipation through the housing itself, and offer an excellent weight-to-weight ratio. However, corrosion can occur depending on the pH of the cooling oil, necessitating surface anodizing. The material of the module housing can be selected based on factors such as strength, chemical reactivity with the refrigerant, weight, and cost. It can consist of a cell 10 housing structure and a sealed space containing a refrigerant.

[0055] Here, the cooling unit 200 can be located inside or outside the module housing 100, and the inside or outside can specifically include the upper, lower and side areas.

[0056] The “upper part” is the area above the battery cell 10 in the module housing 100. It is usually a space that can form a gas exhaust channel. When the cooling unit 200 is located in the upper part of the module housing 100, the interference from the high-temperature gas flowing out when thermal runaway occurs can be minimized and the cooling efficiency can be ensured.

[0057] The “lower part” is the area below the battery cell 10 in the module housing 100. It assists in cooling the lower part in the heat transfer path, and structural support components can also be installed in parallel in this area.

[0058] The “side” includes the left and right or front and rear sides of the module housing 100, which can be used to expand the heat exchange area or to form multiple cooling units 200 in parallel.

[0059] According to one embodiment, Figure 1 A plate-shaped cooling unit (cooling layer) 200 is shown mounted on the upper part of the module housing 100. This is determined to achieve efficient cooling, taking into account the heat distribution characteristics and runaway conditions of the upper part of the battery cell 10. Furthermore, in other embodiments, the aforementioned cooling unit 200 may also be arranged on the lower part (see reference). Figure 2 ) or side (refer to Figure 4 The structure can also be configured with elements at the top and bottom (see reference). Figure 3 In addition, multiple cooling units 200 can be connected in series or in parallel to form flow channels to adjust cooling performance.

[0060] According to embodiments of this disclosure, the thermal management of the entire system can be efficiently achieved by providing a cooling unit 200 at at least one of the upper, lower, and side portions, without being limited to a specific orientation of the module housing 100. In particular, the installation position of the cooling unit 200 can be selected by comprehensively considering factors such as system space constraints, installation orientation, internal cell density, and arrangement structure, thus making it applicable to various forms of energy storage systems (ESS) or battery packs.

[0061] As described above, according to embodiments of this disclosure, since the cooling units 200 can be selectively arranged at various locations within the module housing 100, multiple cooling paths can be provided, reducing temperature deviations in the cells 10 and achieving uniform cooling efficiency. This helps improve the overall thermal management performance of the ESS module, suppresses thermal runaway propagation between the cells 10, and enhances system reliability.

[0062] The cooling unit 200 according to an embodiment of the present disclosure may include a cooling plate 230 having one or more internal cooling channels.

[0063] The aforementioned cooling unit 200 is physically separated and installed on the outside of the module housing 100. While circulating refrigerant circulates inside the cooling unit 200, it exchanges heat with the submerged refrigerant inside the module housing 100, thereby indirectly cooling the battery cell 10.

[0064] The aforementioned cooling plate 230 can typically be manufactured in the form of a flat surface or a thin plate. This plate-like structure forms one or more internal cooling channels, allowing circulating refrigerant to flow from the inlet to the outlet through the flow channels. The cooling channels can be configured as single-loop or multi-loop structures to adjust cooling performance. Here, "internal cooling channel" or "cooling channel" refers to a flow channel formed within the cooling plate material through methods such as injection molding, processing, lamination, or molding, and can include straight, curved, or a combination of both cooling paths.

[0065] As a specific embodiment, when the cooling plate 230 is installed on the upper part of the module housing 100, the cooling plate 230 can be formed of a metal or composite material with high heat transfer efficiency. The circulating refrigerant circulating through the internal flow channels of the cooling plate 230 uses water-based cooling oil PG25 or insulating cooling oil to ensure thermal conductivity and insulation.

[0066] In addition, according to the system design, the cooling plate 230 can be tightly attached to the module housing 100 as an integral part, or it can be installed independently as a physically separate structure.

[0067] According to one embodiment, the cooling plate 230 can be installed on the upper, lower, or side of the module housing 100, and depending on the arrangement of the battery cells and the heat distribution inside the module housing 100, it can be installed on one side of the module housing 100. Furthermore, multiple cooling plates 230 can be configured in series or parallel to adjust the cooling performance in stages.

[0068] This plate-like cooling plate 230 is easy to manufacture and can be modularized into various shapes and sizes, making it suitable for mass production.

[0069] As described above, according to embodiments of this disclosure, the cooling unit 200 is formed by a cooling plate 230 with a plate-like structure having one or more internal cooling channels. The circulating refrigerant circulates uniformly through these cooling channels and efficiently exchanges heat with the submerged refrigerant, thus ensuring the uniformity of the cooling path. Consequently, by improving thermal response speed and reducing cell temperature deviation, the cooling performance of the entire system can be improved.

[0070] Figure 5 This is a schematic diagram of a battery immersion cooling device with a cooling unit 200 having a serpentine tube assembly according to an embodiment of the present disclosure. Figure 6 This is a schematic diagram showing the alignment between the cooling unit 200 of the serpentine tube assembly 240 and the thermal barrier 20 of the battery cell 10 according to an embodiment of the present disclosure.

[0071] As shown in the figure, the cooling unit 200 according to an embodiment of the present disclosure includes a serpentine tube assembly 240 in which a plurality of cooling tubes 242 are arranged in a repeating pattern (e.g., a serpentine, zigzag, or bent or coiled pattern), and the cooling tubes 242 can be aligned in a manner corresponding to the thermal barrier 20 disposed between the cells 10.

[0072] Cooling unit 200 is disposed on the outside or inside of module housing 100 containing battery cell 10 to allow circulating refrigerant to circulate. The cooling pipe 242 is a tubular cooling channel for the flow of cooling oil. According to one embodiment, the cooling pipe 242 is repeatedly arranged and interconnected at a predetermined spacing. For example, the repeated arrangement can form a cooling channel with a serpentine, zigzag, bent, or coil pattern.

[0073] That is, a continuous cooling flow path can be formed by bending and folding a single tube, or a continuous cooling structure can be formed by connecting multiple straight cooling tubes 242 in parallel or in series.

[0074] According to one embodiment, a plurality of cooling tubes 242 arranged in a serpentine tube assembly 240 can be aligned in a manner corresponding to thermal barrier 20 formed between the cells 10.

[0075] The serpentine tube assembly can be positioned at a predetermined distance from the top of the battery cell to ensure an venting path is provided during thermal runaway, thereby minimizing secondary risks such as explosion, overpressure, or combustion propagation. When the thermal barrier is aligned with the cooling tube, heat buildup at the thermal barrier is reduced, and the propagation of the thermal runaway reaction can be blocked in the initial stages.

[0076] The aforementioned thermal barrier 20 is a structure designed to suppress heat transfer between battery cells 10 and prevent the spread of thermal runaway. It is typically made of a material with excellent heat resistance and insulation properties and is located at the boundary between battery cells 10.

[0077] Multiple cooling pipes 242 are aligned in a manner corresponding to this thermal barrier 20, meaning that each cooling pipe 242 is positioned at or near the corresponding barrier location. This alignment provides a structure that does not impede upward gas flow in the event of thermal runaway, thereby enabling concentrated cooling in the boundary region between the cells 10. By concentrating heat removal in the cell boundary region, the propagation of runaway reactions can be blocked.

[0078] As a specific embodiment, refer to Figure 5 and Figure 6Multiple cooling tubes 242 mounted on the upper end of the cell 10 are aligned vertically or horizontally along the inter-cell thermal barrier 20. This ensures that each cooling tube 242 circulates the circulating refrigerant flowing in from the circulating refrigerant inlet 210 along the coil-shaped flow channel and performs heat exchange. This serpentine tube assembly 240 can form one or more loops according to the module design. By circulating insulating oil or circulating refrigerant such as PG25, insulation and thermal conductivity can be ensured.

[0079] As described above, the cooling unit 200 of the serpentine tube assembly 240 according to embodiments of the present disclosure effectively addresses the heat transfer concentration at the cell boundary regions within the battery module, reducing potential heat accumulation on the thermal barrier 20 and minimizing temperature deviations between cells. This ensures system reliability and stability, and in the event of thermal runaway, it can initially prevent the spread of the runaway reaction.

[0080] According to an embodiment of this disclosure, the serpentine tube assembly 240 can be configured to be spaced at a predetermined distance from the upper end of the battery cell 10 so as not to obstruct the upward gas flow in the event of thermal runaway.

[0081] According to one embodiment, the cooling unit 200 includes a serpentine tube assembly 240 in which a plurality of cooling tubes 242 are repeatedly arranged, the serpentine tube assembly 240 being aligned in a manner corresponding to a thermal barrier 20 disposed between the battery cells 10.

[0082] Thermal runaway can be caused by factors such as internal short circuits in the battery cell 10, external impacts, and high-temperature environments. During its occurrence, gas and heat are rapidly generated and released upwards. Therefore, the aforementioned serpentine tube assembly 240 can be positioned at a predetermined distance ("distance") from the upper end of the battery cell 10 to avoid obstructing the upward gas flow generated during thermal runaway. This "distance" refers to a distance ensuring structural and spatial integrity, specifically set to approximately several millimeters to several centimeters, and can be adjusted according to the shape of the battery cell 10, its mounting density, and the expected gas release. The distance can be between 5 mm and 50 mm, preferably between 10 mm and 30 mm, depending on the expected gas emission and the battery cell shape.

[0083] According to the embodiment, to ensure space for upward gas flow, the serpentine tube assembly 240 can be installed inside the upper end cover of the module housing 100, or fixed at a predetermined height at the upper end of the thermal barrier 20 by a support frame or the like. This ensures a flow path for upward gas release and passage, thereby minimizing secondary hazards such as explosions, pressure surges, or combustion spread, and preventing flow resistance due to the structure of the cooling unit 200.

[0084] As described above, by configuring the cooling unit 200 of the serpentine tube assembly 240 according to one embodiment of the present disclosure at a predetermined distance from the upper end of the battery cell 10, a gas discharge path in the event of thermal runaway can be ensured, and the gas is guided to avoid directly impacting the cooling unit 200 or stagnating, thereby improving the safety and durability of the entire system. For example, in a particular embodiment, by ensuring an unobstructed gas discharge path above the battery cell, the device can reduce the risk of pressure buildup that could lead to module rupture, and can easily achieve safe emissions that meet the industrial safety requirements of lithium-ion battery systems.

[0085] Figure 7 This is a schematic diagram of a battery immersion cooling device with a tubular cooling unit according to an embodiment of the present disclosure.

[0086] According to embodiments of the present disclosure, the cooling unit 200 can be a tubular structure 250 comprising a plurality of straight or bent cooling pipes.

[0087] The cooling unit 200 of the aforementioned tubular structure 250 includes multiple pipes through which the circulating refrigerant flows, such as branch cooling pipes 252 and connecting cooling pipes 254 connecting the branch cooling pipes 252. These cooling pipes can have straight or bent shapes. The cooling pipes of the tubular structure 250 are waveguides through which the circulating refrigerant flows, and typically have circular, elliptical, square, or polygonal cross-sections, which can be designed into various shapes according to the structure and space constraints of the battery module.

[0088] According to one embodiment, multiple straight cooling pipes typically refer to cooling paths that are simple and intuitive, enabling efficient circulation of the refrigerant by minimizing resistance in the cooling flow channels. On the other hand, bent cooling pipes are utilized when the cooling unit 200 is positioned within a curved surface or confined space inside or outside the module housing 100, allowing for flexible application to desired locations. For example, the bent structure can be implemented in various shapes such as U-shape, Z-shape, S-shape, or spiral.

[0089] As described above, the cooling unit 200 employing the tubular structure 250 according to an embodiment of the present disclosure has a simple structure and is easy to manufacture, and can be applied to various cell shapes and module structures. For example, the tubular structure 250 can adjust the flow resistance and flow rate by adjusting the length and bending angle of the cooling channel, thus allowing for adjustment of cooling performance under various operating conditions. As a result, the present disclosure can reduce temperature deviations between cells 10 and improve system reliability and lifespan.

[0090] According to an embodiment of the present disclosure, the tubular structure 250 allows the circulating refrigerant to flow in a single direction from the circulating refrigerant inlet 210 to the circulating refrigerant outlet 220.

[0091] According to specific embodiments, such as Figure 7 As shown, the tubular structure 250 allows the circulating refrigerant flowing in from the circulating refrigerant inlet 210 to flow in one direction while passing through multiple cooling pipes. During the flow, the refrigerant exchanges heat with the submerged refrigerant around the battery cell 10 and is then discharged to the outside through the circulating refrigerant outlet 220.

[0092] This unidirectional flow can also be applied to parallel flow channel structures, series flow channel structures, or a combination thereof, and the loop length, number of bends, diameter of cooling pipes, etc. can be adjusted according to the cooling system design.

[0093] This unidirectional flow prevents the stagnation of cooling oil and avoids localized overheating caused by stagnant flow, thereby improving the cooling uniformity of the system.

[0094] As described above, by configuring the tubular structure 250 according to one embodiment of the present disclosure to allow unidirectional flow from the circulating refrigerant inlet 210 to the circulating refrigerant outlet 220, the circulation path of the circulating refrigerant can be predicted and kept stable, and the heat exchange efficiency with the submerged refrigerant can be improved. As a result, the indirect cooling performance of the cell 10 is improved, and the cooling response speed is increased even in the event of thermal runaway, thereby improving the overall system reliability of the ESS module.

[0095] According to one embodiment of the present disclosure, the tubular structure 250 includes branch cooling pipes 252 and connecting cooling pipes 254 connecting them, wherein the connecting cooling pipes 254 may be arranged in parallel or in series.

[0096] The aforementioned branch cooling pipe 252 is used to disperse the cooling oil to multiple directions or multiple areas, and the aforementioned connecting cooling pipe 254 is used to connect the cooling paths of each branch in parallel or series to ensure the flexibility and uniformity of fluid circulation.

[0097] As a specific embodiment, refer to Figure 7 In the tubular structure 250, multiple branch cooling pipes 252 are arranged at predetermined intervals along the length of the battery module, and connecting cooling pipes 254 are disposed between the branch cooling pipes 252, thereby forming a flow channel network. This structure can uniformly disperse the flow rate of the cooling oil and control the circulation of more cooling oil in specific areas where heat is concentrated.

[0098] This parallel configuration improves cooling efficiency and reduces pressure loss, while the series configuration facilitates temperature control based on the flow direction of the cooling oil. Each connecting cooling pipe 254 can be formed into a loop structure or various shapes such as S-shaped, U-shaped, or trapezoidal, and can be designed according to the spacing between the battery cells 10, the type of cooling oil, and the thermal load characteristics of the system.

[0099] As described above, by configuring the tubular structure 250 according to embodiments of the present disclosure into branch cooling pipes 252 and connecting cooling pipes 254 and arranging them in parallel or series, it becomes easier to disperse and concentrate the flow of the circulating refrigerant, and cooling uniformity can be achieved throughout the module. Therefore, even under conditions of rapid heat generation such as thermal runaway, cooling responsiveness can be improved.

[0100] According to one embodiment of the present disclosure, the flow channels of the cooling unit 200 can be connected in parallel or in series in the form of a single loop or multiple loops.

[0101] The cooling unit 200 of this disclosure serves as a heat transfer mechanism, in which the circulating refrigerant flows through the circulating refrigerant inlet 210 into the circulating refrigerant outlet 220, flows along an internal flow channel, and exchanges heat with the immersed refrigerant. The aforementioned flow channel is the path of fluid circulation and can be essentially formed as a single loop or multiple loops, with each loop configured to be connected in parallel or in series.

[0102] According to one embodiment, a single-loop system is a structure in which fluid flows along a single circulation path, while a multi-loop system consists of multiple independent circulation paths, thereby allowing cooling oil to be centrally distributed to specific areas or its flow rate to be controlled by intervals. Such multi-loop systems can be connected in parallel or in series. Parallel connections supply cooling oil to each loop simultaneously, thus providing a flow dispersion effect and improving cooling uniformity, while series connections offer the advantages of simple system configuration and ease of control.

[0103] As a specific embodiment, a single-loop structure can be implemented using a single-loop cooling pipe installed around the periphery of the battery module. The circulating refrigerant is discharged from the circulating refrigerant inlet 210 along a continuous path through the circulating refrigerant outlet 220. In a multi-loop structure, multiple channels can be installed on the upper and side or lower parts, respectively. For example, the upper loop can be provided for immediate response to quickly suppress thermal runaway, while the lower loop can be provided for stable cooling for long-term operation. In a parallel structure, the inflow of each loop is connected to the same main inlet pipe; in a series structure, the outflow of one loop can be connected to the inflow of the next loop.

[0104] According to one embodiment of this disclosure, the circulating refrigerant is selected considering physical properties such as cooling efficiency, insulation characteristics, viscosity, and stability. In one embodiment, PG25 or insulating oil may be used.

[0105] The aforementioned PG25 is a water-based cooling oil, referring to a water-soluble cooling oil in which propylene glycol comprises 25% and the remaining 75% is mixed with purified water in a volume or mass ratio. As a water-based cooling oil, PG25 exhibits excellent heat transfer performance and is commercially readily available, and as a non-toxic substance, it can be widely used. While not limited to a specific concentration, a 25% concentration provides an optimal balance in terms of heat transfer performance, antifreeze properties, and cost-effectiveness for battery cooling applications.

[0106] The aforementioned insulating coolant may include one or more of the following: mineral oil, synthetic oil, natural ester, fluorinated compound, fluorinert, Novec, and inert perfluoropolyether (PFPE). The insulating coolant possesses excellent high insulation, flame retardancy, and chemical stability, and exhibits high reliability under high-temperature conditions.

[0107] The selection of the above-mentioned circulating refrigerant can be made by comprehensively considering system specifications, cell composition, operating temperature range, and electrical insulation requirements.

[0108] According to one embodiment of the present disclosure, the cooling unit 200 may be laminated with a metal heat sink or a phase change material (PCM).

[0109] When combined with metal heat sinks or phase change materials (PCMs) in a laminated manner, the thermal response speed and heat storage capacity of the system can be improved. The metal heat sink performs instantaneous heat dissipation, while the PCM absorbs instantaneous heat through phase change, thereby effectively slowing down the temperature rise inside the system.

[0110] According to one embodiment, the cooling unit 200 circulates the refrigerant along an internal flow channel and exchanges heat with the submerged refrigerant, and may be additionally combined with a metal heat sink or a phase change material.

[0111] The aforementioned layered combination involves physically attaching an auxiliary cooling mechanism with excellent thermal conductivity to the cooling unit 200. For example, the metal heat sink can be made of a metal with high thermal conductivity, such as aluminum, copper, or nickel. The PCM can respond to temperature changes by absorbing or releasing latent heat at a certain temperature.

[0112] Specifically, the metal heat sink can be attached to the outer wall of the cooling unit 200 using thermally conductive adhesive, or it can be integrally molded into the structure. This helps to quickly transfer the heat absorbed by the circulating refrigerant to the outside, thereby contributing to the overall thermal diffusion of the cooling unit 200. On the other hand, the PCM is stacked on the cooling unit 200 with a certain thickness. When the temperature rises sharply, it induces a phase transition from solid to liquid phase and absorbs a large amount of heat. When the temperature drops again, it releases heat and recrystallizes into a solid phase, thus performing a thermal buffering function. For example, the PCM can be paraffin-based, hydrate-based, fatty acid-based, or polymer-based PCM, and its operating temperature can be set in the range of 20°C to 80°C. The specific phase transition temperature is selected according to the normal operating temperature and thermal runaway initiation temperature of the battery cell. For lithium-ion batteries, it is usually between 40°C and 60°C.

[0113] This stacked structure according to one embodiment of the present disclosure improves the thermal response speed and heat storage capacity of the cooling unit. By assisting the cooling unit in performing heat exchange based on the circulating refrigerant cycle, the stability of the entire cooling system can be improved. In particular, even in the event of thermal runaway or a rapid temperature rise, the metal heat sink performs immediate heat dissipation, and the PCM absorbs instantaneous heat, effectively delaying the rise in internal system temperature. This prevents thermal damage to the battery cell 10 and improves the overall stability and reliability of the system.

[0114] Figure 8 This is a flowchart of a battery immersion cooling method according to an embodiment of the present disclosure. In this embodiment, structures that are repeated in the foregoing embodiments will be simplified or omitted in the description.

[0115] As shown in the figure, the battery immersion cooling method according to an embodiment of the present disclosure may include: a step of preparing a module housing to accommodate multiple battery cells (S910); a step of filling the module housing with immersion refrigerant to immerse the battery cells (S920); a step of providing a cooling unit for circulating refrigerant on one side of the module housing (S930); a step of circulating the refrigerant from the circulating refrigerant inlet to the circulating refrigerant outlet in the cooling unit through an internal cooling channel (S940); and a step of indirectly cooling the battery cells by exchanging heat between the circulating refrigerant circulating through the cooling channel and the immersion refrigerant (S950).

[0116] First, a module housing (S910) capable of accommodating multiple battery cells is prepared. The module housing is formed to accommodate multiple battery cells within its internal space and is implemented as a sealed or semi-sealed structure capable of immersion cooling. The battery cells can be of any type: pouch cell, prismatic cell, or cylindrical cell.

[0117] Next, the step of filling the module housing with immersion refrigerant for immersion cooling of the cells (S920) involves completely immersing multiple cells in liquid cooling oil, thereby enabling direct cooling of the entire cell surface. The immersion refrigerant can typically be made of insulating materials such as mineral oil, synthetic oils, natural esters, fluorinated compounds, fluorinerts, Novec, or inert perfluoropolyethers (PFPE). The immersion refrigerant exists in a static or naturally convection state and can maintain a continuous cooling effect through heat exchange with the cooling unit.

[0118] According to one embodiment of this disclosure, the step (S930) of providing a cooling unit for circulating refrigerant on one side of the module housing is a step of achieving an indirect cooling structure by providing an independently operating heat exchange unit outside the battery module. The cooling unit is thermally closely linked to the module housing and can be installed at at least one location on the upper, lower, or side of the module housing. The cooling unit can be formed from at least one of a plate-shaped cooling layer, a serpentine tube assembly, or a tubular structure.

[0119] According to one embodiment of this disclosure, the step (S940) of forming a circulating refrigerant inlet and outlet in the cooling unit and circulating the refrigerant through a flow channel involves forming a flow channel inside the cooling unit that allows cooling oil to flow, and continuously circulating the refrigerant using a pump (e.g., a centrifugal pump, gear pump, etc.). The circulating refrigerant does not directly contact the submerged refrigerant; instead, it performs indirect cooling by exchanging heat with the submerged refrigerant while moving along the flow channel structure. The flow channel can be formed as a single-loop or multi-loop structure and can be designed for parallel or series flow. Here, to improve thermal conductivity, the cooling unit can be laminated with a metal heat sink or a phase change material.

[0120] According to one embodiment of this disclosure, the step (S950) of indirectly cooling the battery cell by exchanging heat between the circulating refrigerant circulating through the aforementioned flow channel and the aforementioned submerged refrigerant can suppress the temperature rise of the battery cell by stably reducing the temperature of the submerged refrigerant. The circulating refrigerant is linked with an external heat exchanger or an external cooling system to achieve stable thermal control over a long period of time, and can effectively control the temperature rise even in the event of thermal runaway.

[0121] Although the steps described above are in a specific order, it should be understood that, where technically feasible, these steps may be performed in a different order or simultaneously. For example, step S930 (setting up the cooling device) may be performed before step S920 (filling and immersing the refrigerant), and these steps may also be performed simultaneously.

[0122] As described above, the immersion cooling apparatus and method according to embodiments of this disclosure provide a dual cooling path by combining direct cooling through the immersion refrigerant inside the module housing and indirect cooling based on circulating refrigerant through an external cooling unit. This guides a rapid and stable temperature drop in the event of thermal runaway, thereby improving the reliability and safety of the system. Furthermore, in the event of thermal runaway, it can effectively block the thermal diffusion from the initial heat source.

[0123] Furthermore, since the circulating refrigerant continuously circulates through the flow channels formed in the cooling unit on one side of the module housing, the local temperature rise of the immersed refrigerant can be suppressed.

[0124] Therefore, the dual cooling method according to one embodiment of the present disclosure can ensure system safety and reliability in various industrial application fields such as ESS (energy storage system), EV (electric vehicle), UPS (uninterruptible power supply) by suppressing thermal runaway, improving cooling efficiency or uniformizing cell temperature.

[0125] The above description is merely an example of applying the principles of this disclosure, and other configurations may be further included without departing from the scope of this disclosure. For example, at least some of the various embodiments of this disclosure described above may be combined.

Claims

1. A battery immersion cooling device, comprising: A module housing that houses multiple battery cells and contains an impregnating refrigerant that immerses the battery cells; A cooling unit is disposed on at least one side of the module housing and is supplied with circulating refrigerant. The cooling unit includes a circulating refrigerant inlet and a circulating refrigerant outlet; The circulating refrigerant exchanges heat with the submerged refrigerant while circulating through the flow channel of the cooling unit to indirectly cool the battery cell.

2. The battery immersion cooling device according to claim 1, wherein: The cooling unit is disposed in at least one of the upper, lower and side portions of the module housing.

3. The battery immersion cooling device according to claim 1, wherein: The cooling unit includes a cooling plate with multiple internal cooling channels.

4. The battery immersion cooling device according to claim 1, wherein: The cooling unit includes a serpentine tube assembly with multiple cooling tubes arranged in a reciprocating pattern; The cooling pipes are aligned in a manner corresponding to the thermal barrier barrier disposed between adjacent cells in the battery cell.

5. The battery immersion cooling device according to claim 4, wherein: The serpentine tube assembly is positioned at a predetermined distance from the upper end of the battery cell.

6. The battery immersion cooling device according to claim 1, wherein: The cooling unit is a tubular structure comprising multiple straight or bent cooling pipes.

7. The battery immersion cooling device according to claim 6, wherein: In the tubular structure, the circulating refrigerant flows in a single direction from the circulating refrigerant inlet to the circulating refrigerant outlet.

8. The battery immersion cooling device according to claim 6, wherein: The tubular structure includes branch cooling pipes and connecting cooling pipes that connect the branch cooling pipes; The connecting cooling pipes are arranged in parallel or in series.

9. The battery immersion cooling device according to claim 1, wherein: The flow channels of the cooling unit are connected in parallel or in series in the form of a single loop or multiple loops.

10. The battery immersion cooling device according to claim 1, wherein: The circulating refrigerant includes one or more of the following: propylene glycol / aqueous solution, mineral oil, synthetic oil, natural ester, synthetic ester, fluorocarbon, perfluorinated fluid, hydrofluoroether fluid, and perfluoropolyether fluid.

11. The battery immersion cooling device according to claim 1, wherein: The cooling unit is laminated with a metal heat sink for immediate heat dissipation or a phase change material for absorbing latent heat.

12. A battery immersion cooling method, comprising: The steps for preparing a module housing to accommodate multiple battery cells; The step of filling the module housing with an impregnation refrigerant to immerse the battery cells; The step of providing a cooling unit having a circulating refrigerant inlet and a circulating refrigerant outlet on at least one side of the module housing, and forming a flow channel between the circulating refrigerant inlet and the circulating refrigerant outlet; The step of circulating the refrigerant from the refrigerant inlet through the flow channel of the cooling unit to the refrigerant outlet; The step of indirectly cooling the battery cell by exchanging heat between the circulating refrigerant circulating through the flow channel and the submerged refrigerant.

13. The battery immersion cooling method according to claim 12, wherein: The cooling unit is installed in at least one of the upper, lower and side portions of the module housing.

14. The battery immersion cooling method according to claim 12, wherein: The cooling unit includes a cooling plate that forms one or more internal cooling channels.

15. The battery immersion cooling method according to claim 12, wherein: The cooling unit is formed as a serpentine tube assembly with multiple cooling tubes arranged in a repetitive pattern; The cooling pipes are aligned in a manner corresponding to the thermal barrier barrier disposed between adjacent cells in the battery cell.

16. The battery immersion cooling method according to claim 15, wherein: The serpentine tube assembly is set at a predetermined distance from the upper end of the battery cell.

17. The battery immersion cooling method according to claim 12, wherein: The cooling unit is formed as a tubular structure comprising multiple straight or bent cooling pipes.

18. The battery immersion cooling method according to claim 17, wherein: The tubular structure is configured such that the refrigerant flows in a single direction from the refrigerant inlet to the refrigerant outlet.

19. The battery immersion cooling method according to claim 17, wherein: The tubular structure is formed into branch cooling pipes and connecting cooling pipes; The connecting cooling pipes are configured to be connected in parallel or in series.

20. The battery immersion cooling method according to claim 12, wherein: The cooling unit is stacked with a metal heat sink for immediate heat dissipation or a phase change material for absorbing latent heat.

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