Battery pack

Abstract

A battery pack is configured to suppress a fire by spraying a coolant from above or immersing at least a portion of the battery pack in the coolant in response to the fire occurring in the battery pack. In response to a fire occurring in the battery pack, coolant may be sprayed from above to function as a sprinkler. By immersing at least a portion of the battery pack in a coolant, fire can be extinguished and heat propagation can be suppressed. The safety of the battery pack can be improved since the fire can be extinguished immediately and heat propagation can be prevented even when the battery cells reach thermal runaway.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority and benefit of Korean Patent Application No. 10 - 2023 - 0094578, filed with the Korean Intellectual Property Office on July 20, 2023, the entire disclosure of which is incorporated herein by reference. Technical field

[0003] Embodiments of the present disclosure relate to a battery pack in which when a fire occurs in the battery pack, fire suppression can be performed by spraying a coolant from above or immersing at least a part of the battery pack in the coolant. Background art

[0004] Generally, a battery pack includes a plurality of battery cells, bus bars, and a circuit board. The bus bars electrically connect the battery cells to the outside, and the circuit board is electrically connected to the bus bars and has various circuits and components mounted thereon.

[0005] The plurality of battery cells may be arranged on a carrier plate. The carrier plate may support the weight of the battery cells and cool the battery cells. For example, a coolant may absorb heat from the battery cells while flowing along a flow path of the carrier plate to reduce the heat of the battery cells. However, if a fire occurs, a structure that only cools the lower part of the battery cells has a problem of being insufficient to prevent thermal runaway and thermal propagation of the battery cells, which may cause the temperature to rise to 1000°C.

[0006] The above - mentioned information disclosed in the background art of the present disclosure is only for improving the understanding of the background of the present disclosure, and accordingly may include information that does not constitute related art. Summary of the utility model

[0007] Embodiments of the present disclosure relate to a battery pack in which when a fire occurs in the battery pack, fire suppression can be performed by spraying a coolant from above or immersing at least a part of the battery pack in the coolant.

[0008] A battery pack according to an embodiment of the present disclosure includes: a battery cell including an exhaust hole; an upper cooling unit on the battery cell, the upper cooling unit being filled with a coolant and including injection holes corresponding to the exhaust holes; and a lower cooling unit in contact with a lower part of the battery cell and filled with a coolant. The injection holes in the upper cooling unit correspond to the exhaust holes of the battery cells, and the upper cooling unit is configured to spray the coolant through the injection holes corresponding to the battery cells in which a fire has occurred.

[0009] The upper cooling unit may be in contact with the battery cell.

[0010] The injection holes may have a diameter larger than the diameter of the exhaust holes.

[0011] When a fire occurs in the battery cells, the spray holes corresponding to the battery cells where the fire occurs may be opened.

[0012] The spray hole may be configured to open by heat of exhaust gas sprayed from the exhaust hole of the battery cell in which a fire occurs.

[0013] The coolant may be propylene glycol.

[0014] The battery pack may further include a fire detection unit configured to detect a temperature increase of the battery cells and / or generation of combustion gas.

[0015] A battery pack according to an embodiment of the present disclosure includes: a battery cell; a housing that houses the battery cell; a coolant inlet on one side surface of the housing; and a coolant outlet on the other side surface of the housing. When a fire occurs in a battery cell, coolant is introduced into the housing through the coolant inlet, thereby at least partially submerging the battery cell.

[0016] The battery cells may be spaced apart from a bottom surface of the case by a preset height.

[0017] When a fire does not occur, the coolant may be filled in the case to a preset height from a bottom surface of the case, and the coolant may contact the bottom surfaces of the battery cells.

[0018] The preset height may be the same as a thickness of the battery cell with respect to a direction in which the plurality of battery cells are arranged.

[0019] The height of the case may be higher than that of the battery cell, and when a fire occurs in the battery cell, the entire battery cell may be immersed in the coolant with respect to the height of the battery cell.

[0020] When a fire occurs in a battery cell, approximately one-third to approximately one-half of the battery cell may be immersed in the coolant with respect to the height of the battery cell.

[0021] The coolant may be propylene glycol.

[0022] The battery pack may further include a fire detection unit configured to detect a temperature increase of the battery cells and / or generation of combustion gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 FIG1 is an exploded perspective view illustrating a battery pack according to one embodiment of the present disclosure.

[0024] Figure 2 A diagram illustrating a battery cell and an upper cooling unit in a state where a fire has occurred.

[0025] Figure 3 is a perspective view illustrating a battery pack according to another embodiment of the present disclosure.

[0026] Figure 4 is Figure 3 a cross-sectional view of.

[0027] Figure 5 is a perspective view of a battery pack according to another embodiment of the present disclosure. Detailed Description

[0028] Embodiments of the present disclosure are provided to more fully describe the present disclosure to those skilled in the art. The following embodiments can be modified into various other forms, and the scope of the present disclosure is not limited to the following embodiments. On the contrary, these embodiments are provided to make the present disclosure more meaningful and complete, and to fully convey the spirit of the present disclosure to those skilled in the art.

[0029] Further, in the following drawings, for convenience and clarity of description, the dimensions (e.g., thickness) of each layer are exaggerated, and the same reference numerals indicate the same elements in the drawings. As used in this specification, the term "and / or" includes any one and all combinations of one or more of the listed items. Further, "connected" as used in this specification not only refers to the case where component A and component B are directly connected, but also refers to the case where component C is interposed between component A and component B to indirectly connect component A and component B.

[0030] The terms used in this specification are used to describe specific embodiments and are not intended to limit the present disclosure. As used in this specification, the singular form may include the plural form unless the context clearly indicates otherwise. Further, when used in this specification, "comprising" and / or "including" specify the presence of the recited features, numbers, steps, operations, components, elements, and / or groups thereof, and do not preclude the presence or addition of one or more other features, numbers, operations, components, elements, and / or groups.

[0031] Although terms such as "first", "second", etc. are used in this specification to describe various components, parts, regions, layers, and / or portions, it is obvious that these components, parts, regions, layers, or portions should not be limited by these terms. These terms are only used to distinguish one component, part, region, layer, or portion from another component, part, region, layer, or portion. Accordingly, a first component, part, region, layer, or portion to be described later may be referred to as a second component, part, region, layer, or portion without departing from the teachings of the present disclosure.

[0032] Spatial-related terms (such as "beneath", "below", "under", "above", and "on") are used to facilitate understanding of the relationship between one element or feature shown in the drawings and another element or feature. These spatial-related terms are provided to easily understand the present disclosure according to various process states or usage states of the present disclosure, and are not intended to limit the present disclosure. For example, when the element or feature in the drawings is inverted, the element described as "under" or "below" becomes "on" or "beneath". Accordingly, "beneath" encompasses the concepts of "above" or "below".

[0033] Hereinafter, reference will be made to Figure 1 and Figure 2 describe in detail a battery pack according to an embodiment of the present disclosure.

[0034] Figure 1 FIG. is an exploded perspective view illustrating a battery pack according to an embodiment of the present disclosure. Figure 2 FIG. is a schematic diagram illustrating a battery cell 110 and an upper cooling unit 200 during a fire in a battery cell 110.

[0035] A battery pack according to an embodiment of the present disclosure may include a battery module 100, an upper cooling unit 200, and a lower cooling unit 300.

[0036] As Figure 1 shown, the battery module 100 may include a plurality of battery cells 110, a pair of end plates 120, a pair of side plates 130, a plurality of bus bars 140, a bus bar bracket 150, and a circuit board 160.

[0037] In one or more embodiments, each of the battery cells 110 may be a lithium-ion secondary battery having a cuboid shape. The plurality of battery cells 110 may be arranged in a row in one direction. In one or more embodiments, the plurality of battery cells 110 may be arranged such that the relatively wide plate surfaces of the battery cells 110 face each other. Adjacent battery cells 110 may be arranged in close contact with each other. In one or more embodiments, a separator of an organic material or an inorganic material may be provided between adjacent battery cells 110 to prevent heat transfer between the battery cells 110.

[0038] Each battery cell 110 may include a cuboid-shaped case 111, an electrode assembly accommodated in the case 111, and a cover plate 112 for sealing an opening of the case 111. The electrode assembly is accommodated in the case 111 together with an electrolyte (e.g., a liquid electrolyte, a gel electrolyte, or a solid electrolyte). The electrolyte may contain a lithium salt (such as LiPF6, LiBF4, etc.) and an organic solvent (such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or dimethyl carbonate (DMC)). The case 111 may be made of a metal (such as aluminum or stainless steel).

[0039] The electrode assembly can be a wound-core type electrode assembly in which a positive electrode plate and a negative electrode plate are wound together with a separator therebetween, or the electrode assembly can be a stacked type electrode assembly in which a positive electrode plate and a negative electrode plate are stacked together with a separator therebetween. The positive electrode plate and the negative electrode plate can each include a coated area of a current collector (such as a thin metal foil) that can be coated with an active material and an uncoated area of the current collector that is not coated with the active material. In one or more embodiments, the coated area of the positive electrode plate can include an active material (such as a transition metal oxide) on a base material that is a metal foil (such as aluminum foil). In one or more embodiments, the coated area of the negative electrode plate can include an active material (such as carbon, graphite, etc.) on a base material that is a metal foil (such as copper foil or nickel foil).

[0040] The uncoated area of the positive electrode plate (positive electrode uncoated area) can be at one side end portion of the positive electrode plate in the longitudinal direction of the positive electrode plate. The uncoated area of the negative electrode plate (negative electrode uncoated area) can be at one side end portion of the negative electrode plate in the longitudinal direction of the negative electrode plate. The positive electrode uncoated area and the negative electrode uncoated area can be located on opposite side surfaces of the coated area. A positive electrode tab can be connected to the positive electrode uncoated area, and a negative electrode tab can be connected to the negative electrode uncoated area.

[0041] A cover plate 112 is coupled to the housing 111 and covers the opening of the housing 111. The cover plate 112 includes a positive electrode terminal 113 and a negative electrode terminal 114 that protrude outward and are electrically connected to the positive electrode plate and the negative electrode plate of the electrode assembly, respectively. Further, an exhaust hole 115 that communicates with the inside of the housing 111 can be in the cover plate 112. An exhaust member including a notch can be installed on the exhaust hole 115, and the notch is configured to open by a preset pressure.

[0042] The positive electrode terminal 113 can be electrically connected to the positive electrode plate through a positive electrode tab. The negative electrode terminal 114 can be electrically connected to the negative electrode plate through a negative electrode tab. A terminal connection member for electrically connecting the positive electrode terminal 113 and the positive electrode tab can be between the positive electrode terminal 113 and the positive electrode tab. The upper portion of the terminal connection member can be in a hole in the positive electrode terminal 113, and the lower portion of the terminal connection member can be welded to the positive electrode tab. Similarly, a terminal connection member can be between the negative electrode terminal 114 and the negative electrode tab.

[0043] A pair of end plates 120 are arranged to face the battery cells 110 at both ends among the plurality of battery cells 110. A pair of side plates 130 are orthogonally (or substantially orthogonally) coupled to the pair of end plates 120. Refer to Figure 1, the pair of end plates 120 contact the battery cells 110 at both ends and support a plurality of battery cells 110 in the front-rear direction. The pair of side plates 130 support a plurality of battery cells 110 in the left-right direction.

[0044] A plurality of bus bars 140 are electrically connected to each of the plurality of battery cells 110. In one or more embodiments, the positive electrode terminals 113 and the negative electrode terminals 114 of adjacent battery cells 110 may be electrically connected through the bus bar 140. Thus, since the plurality of battery cells 110 are electrically connected to each other, the battery pack can be used as a power device. The bus bar 140 can be connected to the positive electrode terminal 113 and the negative electrode terminal 114 by any suitable method (such as welding, etc.).

[0045] The bus bar holder 150 can be on the cover plate 112 and support a plurality of bus bars 140. A plurality of through holes can be in the bus bar holder 150, through which the positive electrode terminal 113 and the negative electrode terminal 114 are exposed. Accordingly, the bus bar 140 can be electrically connected to the positive electrode terminal 113 and the negative electrode terminal 114. The bus bar holder 150 can be made of an insulating material. The area of the upper part of the battery pack except for the bus bar 140 and the positive electrode terminal 113 and the negative electrode terminal 114 can be insulated by the bus bar holder 150.

[0046] The circuit board 160 on which various circuits and components are mounted can be on the bus bar holder 150. The bus bar 140 is electrically connected to the circuit board 160. The circuit board 160 is electrically connected to the outside of the battery pack through a separate connector.

[0047] The upper cooling unit 200 can be on the battery module 100. A coolant can be accommodated (e.g., filled or included) in the upper cooling unit 200. The lower cooling unit 300 can be under the battery module 100. A coolant can be accommodated (e.g., filled or included) in the lower cooling unit 300. In one or more embodiments, the upper cooling unit 200 and the lower cooling unit 300 are in contact with the upper and lower parts of the battery module 100 (e.g., a plurality of battery cells 110), respectively. Accordingly, the coolant is configured to cool the battery module 100 by absorbing heat from each of the upper and lower parts of the battery module 100 when flowing through the internal flow paths of the upper cooling unit 200 and the lower cooling unit 300. Thus, when the cooling units are in contact with both the upper and lower parts of the battery module 100, the problem of temperature imbalance in the battery cells 110 can be solved. That is, the temperature deviation in the battery cells 110 can be reduced, and accordingly, the current imbalance can be reduced, and the life of the battery cells 100 can be increased.

[0048] In the related art, only the lower part of the battery cell is cooled, so under fast charging conditions, there may be a temperature imbalance of about 23 °C up and down in the battery cell. This up and down temperature imbalance causes current imbalance and deterioration of the battery cell performance. For example, it is known that the thermal decomposition of the solid electrolyte interface (SEI) occurs in the upper part, and the Li plating phenomenon occurs in the lower part, which adversely affects the life. Accordingly, a uniform (or substantially uniform) temperature distribution of the battery cell solves the electrical problem and the life problem.

[0049] In one or more embodiments, a plurality of injection holes 220 may be in the upper cooling unit 200 corresponding to the exhaust holes 115 of the plurality of battery cells 110. In response to a fire occurring in at least one of the plurality of battery cells 110, the coolant in the upper cooling unit 200 may be injected through the injection holes 220 corresponding to the battery cell 110 in which the fire occurs.

[0050] The plurality of injection holes 220 may be in the lower surface of the upper cooling unit 200. The shape of the injection holes 220 may correspond to the shape of the exhaust holes 115. In one or more embodiments, the exhaust holes 115 have an oval shape, and the injection holes 220 may also have an oval shape. In addition, in one or more embodiments, the injection holes 220 may have a size (e.g., a larger diameter) larger than the size (e.g., the diameter) of the exhaust holes 115.

[0051] When no fire occurs in the battery cell 110, the plurality of injection holes 220 are closed. In response to a fire occurring, the injection holes 220 corresponding to the battery cell 110 in which the fire occurs are configured to open. The injection holes 220 may be opened due to the heat of the exhaust gas ejected or discharged from the exhaust holes 115 of the battery cell 110 in which the fire occurs.

[0052] Figure 2 The figure shows the battery cells 110 and the upper cooling unit 200 spaced apart from each other, and the case where the coolant is injected through one of the injection holes 220 corresponding to the battery cell 110 in which the fire occurs. In the illustrated embodiment, the injection holes 220 may be closed by a film 240. According to this embodiment, the film 240 may be coated on the upper cooling unit 200 or adhered to the upper cooling unit 200 to block the injection holes 220. In one or more embodiments, the upper cooling unit 200 may include one or more plugs coupled to the injection holes 220.

[0053] In one or more embodiments, the film 240 is configured to melt due to the exhaust gas ejected from one or more exhaust holes 115. In one or more embodiments, the film 240 may be polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), acrylonitrile-butadiene-styrene copolymer (ABS) resin, acrylonitrile-styrene copolymer (AS) resin, methacrylic resin (e.g., polymethyl methacrylate (PMMA)), polyvinyl alcohol (PVA), or polyvinylidene chloride (PVDC). In one or more embodiments, the melting temperature of the film 240 may be 150 °C. Accordingly, in response to the temperature of the exhaust gas exceeding 150 °C in response to a fire occurring in the battery cell, the film 240 may melt. In response to the film 240 melting, the injection holes 220 may open, and the coolant in the upper cooling unit 200 may be ejected through the injection holes 220 onto the exhaust holes 115 of the battery cell 110 where the fire has occurred.

[0054] The upper cooling unit 200 is on the battery module 100 and is configured to cool the battery module 100. In response to a fire occurring, the upper cooling unit 200 may operate like a sprinkler and eject the coolant onto the upper part of the battery cell 110 to extinguish the fire in the battery cell 110 immediately (or substantially immediately). Accordingly, heat transfer to other battery cells 110 adjacent to the battery cell 110 where the fire has occurred may be suppressed. That is, since the fire can be extinguished immediately (or substantially immediately) even when the battery cell 110 reaches thermal runaway and heat transfer can be prevented, the safety of the battery pack can be improved.

[0055] In one or more embodiments, the coolant may be a heat-conductive material that is configured to cool the battery cell 110 when no fire occurs and act as a fire extinguishing agent in response to a fire occurring. In one or more embodiments, the coolant may be propylene glycol. Propylene glycol is effective as both a heat-conductive material and a fire extinguishing agent, is harmless to the human body, and is inexpensive. Ethylene glycol, which is used as a coolant in many internal combustion engine vehicles, has excellent performance and is inexpensive, but is harmful to the human body.

[0056] In addition, in one or more embodiments, the battery pack may include a fire detection unit that is configured to detect a sudden temperature rise of the battery module 100 (e.g., a temperature rise of at least one of the plurality of battery cells 110) and / or the generation of combustion gas.

[0057] Now reference will be made to Figure 3 and Figure 4 describe a battery pack according to another embodiment of the present disclosure.

[0058] Figure 3 is a perspective view illustrating a battery pack according to another embodiment of the present disclosure. Figure 4 isFigure 3 Cross-sectional view.

[0059] According to another embodiment of the present disclosure, the battery pack may include a battery module 100, an upper cooling unit 200, and a housing 400. The battery module 100 and the upper cooling unit 200 are the same as described above, and the upper cooling unit 200 is omitted in Figure 3 and Figure 4 Hereinafter, the description will focus on the structure of the housing 400 and a part of the battery module 100 being immersed in the coolant in response to a fire.

[0060] In one or more embodiments, the housing 400 has a rectangular parallelepiped shape and may accommodate the battery module 100 therein. A coolant inlet 420 is in one side surface of the housing 400. A coolant outlet 440 is in the other side surface (e.g., the opposite side surface) of the housing 400. The coolant may be filled in the housing 400. A pair of support members 460 may be provided to face each other on opposite sides of the battery module 100 in the housing 400. In one or more embodiments, the support members 460 may extend in the longitudinal direction of the housing 400.

[0061] The position of the battery module 100 may be fixed in the housing 400 by fixing the battery module 100 to the support members 460 by fastening (e.g., threaded connection) and / or laser welding. In the embodiment shown in Figure 4 , the battery module 100 may be spaced apart from the bottom surface of the housing 400 by a preset height h. In one or more embodiments, the lower portion of each support member 460 may be bent and extended into the interior of the housing 400 to support the battery module 100. In one or more embodiments, the preset height h may have a value that is the same (or substantially the same) as the thickness of one of the battery cells 110 with respect to (e.g., along) the direction in which the plurality of battery cells 110 are arranged.

[0062] In one or more embodiments, under normal operating conditions (i.e., no fire occurs in the battery cells 110), the coolant is filled in the housing 400 to a certain height h from the bottom surface of the housing 400. The coolant may contact at least the bottom surface of the battery module 100 (e.g., the plurality of battery cells 110). Accordingly, the coolant in the housing 400 may be used to cool the battery module 100 by absorbing heat from the battery module 100. In one or more embodiments, since the coolant in the housing 400 is used to cool the lower portion of the battery module 100, the lower cooling unit 300 of the above embodiment may be replaced by a bottom plate for supporting the plurality of battery cells 110 (e.g., the lower cooling unit 300 may be omitted).

[0063] In response to a fire occurring in at least one of the plurality of battery cells 110, coolant is introduced into the housing 400 through the coolant inlet 420. Accordingly, the battery module 100 can be immersed in the coolant. In one or more embodiments, approximately one-third to approximately one-half of the height of the battery module 100 can be immersed in the coolant. However, the present disclosure is not limited thereto, and even during normal operation (i.e., when no fire occurs), a state in which approximately one-third to approximately one-half of the battery module 100 is immersed in the coolant can be maintained.

[0064] In this embodiment, since the lower part of the battery module 100 is immersed in the coolant during normal operating conditions, and the upper cooling unit 200 is configured to spray coolant in response to the occurrence of a fire, both the upper and lower parts of the battery module 100 can be cooled. Further, when a fire occurs, the upper cooling unit 200 can be used as a sprinkler.

[0065] In response to a fire occurring in one or more of the battery cells 110, coolant is sprayed from above, and a part of the battery module 100 is immersed in the coolant, and thus the fire can be extinguished immediately (or substantially immediately). Further, heat transfer to other battery cells 110 adjacent to the battery cell 110 in which the fire has occurred can be suppressed. That is, since the fire can be extinguished immediately (or substantially immediately) and heat transfer can be prevented even when the battery cell 110 reaches thermal runaway, the safety of the battery pack can be improved.

[0066] In addition, in one or more embodiments, only the lower part of the battery module 100 is immersed in the coolant, so the bus bar 140 and the circuit board 160 in the upper part of the battery module 100 can be separated from the coolant. Further, since only a part of the battery module 100 is immersed in the coolant, the height of the housing 400 does not need to be higher than the height of the battery module 100. Accordingly, the weight of the housing 400 and the weight of the coolant can be reduced, thereby reducing the total weight of the battery pack.

[0067] In one or more embodiments, propylene glycol can be used as the coolant.

[0068] In addition, in one or more embodiments, a fire detection unit configured to detect a sudden temperature rise and / or generation of combustion gas of the battery module 100 can be included. In response to the sudden temperature rise and / or generation of combustion gas of the battery module 100 detected by the fire detection unit, coolant can be introduced into the housing 400 through the coolant inlet 420 (e.g., immediately or substantially immediately).

[0069] The coolant exiting from the coolant outlet 440 recirculates through the coolant inlet 420, and the coolant exiting from the coolant outlet 430 can enter the coolant inlet 420 after being cooled by the cooler. In this way, the coolant can circulate in a closed-loop manner. In one or more embodiments, the temperature of the coolant can be maintained at approximately (substantially) 25°C.

[0070] Reference will be made to Figure 5 describe in detail a battery pack according to another embodiment of the present disclosure.

[0071] Figure 5 FIG. is a perspective view illustrating a battery pack according to another embodiment of the present disclosure.

[0072] The battery pack according to another embodiment of the present disclosure may include a battery module 100 and a housing 400. Since the battery module 100 is the same as described above, the housing 400 and the structure in which the entire battery module 100 is immersed in the event of a fire will be mainly described hereinafter.

[0073] The housing 400 has a rectangular parallelepiped shape as Figure 4 described, and can accommodate the battery module 100 therein. The coolant inlet 420 is in one side surface of the housing 400, and the coolant outlet 440 is in the other side surface (e.g., the opposite side surface) of the housing 400. The coolant can be filled in the housing 400. In one or more embodiments, the battery module 100 can be fixed to a pair of support members 460 and spaced apart from the bottom surface of the housing 400 by a preset height h. Accordingly, since the coolant is filled in the housing 400 to a certain height h from the bottom surface of the housing 400 under normal operating conditions (i.e., no fire occurs in any battery cell 110), the coolant can contact the bottom surface of the battery module 100. Since the coolant in the housing 400 is used to cool the lower part of the battery module 100, the lower cooling unit 300 of the above embodiment can be replaced by a bottom plate for supporting a plurality of battery cells 110 (e.g., the lower cooling unit 300 can be omitted).

[0074] In one or more embodiments, the housing 400 may have a height higher than the height of the battery module 100. Accordingly, in response to a fire occurring in at least one of the plurality of battery cells 110, the coolant is introduced into the housing 400 through the coolant inlet 420, and thus the entire battery module 100 can be immersed in the coolant (e.g., the entire height of the battery module 100 can be immersed in the coolant). However, the present disclosure is not limited thereto, and the state in which the entire battery module 100 is immersed in the coolant can be maintained even when no fire occurs.

[0075] In one or more embodiments, since the entire battery module 100 is immersed in the coolant, the above-described upper cooling unit 200 may be omitted. Accordingly, in one or more embodiments, the upper cooling unit 200 may be replaced by a top plate that is coupled to a pair of end plates 120 and a pair of side plates 130 and thus covers the upper surface of the battery module 100.

[0076] Accordingly, in response to a fire occurring, since the entire battery module 100 is immersed in the coolant, the fire can be extinguished immediately (or substantially immediately). Further, heat propagation to other battery cells 110 adjacent to the battery cell 110 where the fire has occurred can be suppressed. That is, since the fire can be extinguished immediately (or substantially immediately) even when the battery cell 110 reaches thermal runaway and heat propagation can be prevented, the safety of the battery pack can be improved. Further, in response to thermal runaway occurring, the coolant can be used as a damper to suppress the explosion force.

[0077] In one or more embodiments, propylene glycol can be used as the coolant.

[0078] In addition, in one or more embodiments, a fire detection unit configured to detect a sudden temperature rise and / or generation of combustion gas of the battery module 100 may be included. In response to the sudden temperature rise and / or generation of combustion gas of the battery module 100 detected by the fire detection unit, the coolant can be introduced into the housing 400 through the coolant inlet 420 (e.g., immediately or substantially immediately).

[0079] The coolant exiting from the coolant outlet 440 is recycled through the coolant inlet 420 again, and the coolant exiting from the coolant outlet 430 can enter the coolant inlet 420 after being cooled by a cooler. In this way, the coolant can circulate in a closed loop. Accordingly, the temperature of the coolant can be maintained at approximately (roughly) 25°C.

[0080] According to an embodiment of the present disclosure, in response to a fire occurring in the battery pack, the coolant can be sprayed onto the battery pack from above to be used as a sprinkler. In one or more embodiments, by immersing at least a part of the battery pack in the coolant, the fire can be extinguished and heat propagation can be suppressed. That is, since the fire can be extinguished immediately even when the battery cell reaches thermal runaway and heat propagation can be prevented, the safety of the battery pack can be improved.

[0081] Further, when the coolant contacts the upper and lower portions of the battery pack, the problem of temperature imbalance in the battery cells can be solved. That is, the temperature deviation in the battery cells can be reduced, and accordingly the current imbalance can be reduced, and the lifespan of the battery cells can be increased.

[0082] Furthermore, propylene glycol can act as a coolant for battery cells when there is no fire, and can act as a fire extinguishing agent when a fire occurs. Therefore, it is effective and harmless to humans.

[0083] The above description is only some embodiments for implementing the present disclosure, and the present disclosure is not limited to the above embodiments. As claimed in the claims, the technical spirit of the present disclosure extends to the extent that various modifications can be made by those skilled in the art without departing from the gist of the present disclosure.

Claims

1. A battery pack, characterized in that, The battery pack includes: a plurality of battery cells, including a plurality of vent holes; an upper cooling unit on the battery cells, the upper cooling unit including a coolant and a plurality of injection holes; and a lower cooling unit in contact with a lower portion of the plurality of battery cells, the lower cooling unit including the coolant, wherein the plurality of injection holes in the upper cooling unit correspond to the plurality of vent holes of the plurality of battery cells, and wherein the upper cooling unit is configured to inject the coolant through at least one injection hole corresponding to the at least one battery cell among the plurality of battery cells in response to a fire occurring in at least one battery cell among the plurality of battery cells.

2. The battery pack according to claim 1, wherein, The upper cooling unit is in contact with the plurality of battery cells.

3. The battery pack according to claim 2, wherein, The plurality of injection holes have a diameter larger than that of the plurality of vent holes.

4. The battery pack according to claim 2, characterized in that, The injection holes are configured to open in response to the fire occurring in the corresponding battery cell among the plurality of battery cells.

5. The battery pack according to claim 4, characterized in that, The injection holes are configured to open in response to the heat of the exhaust gas ejected from the vent hole in the corresponding battery cell among the plurality of battery cells where the fire occurs.

6. The battery pack according to any one of claims 1 to 5, characterized in that, The coolant is propylene glycol.

7. The battery pack according to any one of claims 1 to 5, characterized in that, The battery pack further includes a fire detection unit configured to detect an increase in temperature or generation of combustion gas in at least one battery cell among the plurality of battery cells.

8. A battery pack, characterized in that, The battery pack includes: a plurality of battery cells; a housing that houses the plurality of battery cells; a coolant inlet in one side surface of the housing; and a coolant outlet in the other side surface of the housing, wherein the battery pack is configured to introduce the coolant into the housing through the coolant inlet and immerse at least a portion of the plurality of battery cells in the coolant in response to a fire occurring in at least one battery cell among the plurality of battery cells.

9. The battery pack according to claim 8, characterized in that, The plurality of battery cells are spaced apart from the bottom surface of the housing by a preset height.

10. The battery pack according to claim 9, characterized in that, When the fire does not occur in the plurality of battery cells, the coolant fills the housing to a preset height starting from the bottom surface of the housing, and wherein the coolant contacts the bottom surfaces of the plurality of battery cells.

11. The battery pack according to claim 9, characterized in that, The preset height is the same as the thickness of one battery cell among the plurality of battery cells along the arrangement direction of the plurality of battery cells.

12. The battery pack according to claim 8, wherein: the height of the housing is higher than the height of the battery cell; and the battery pack is configured to immerse the entire height of the battery cell in the coolant in response to the fire occurring in the at least one battery cell.

13. The battery pack according to claim 8, wherein, The battery pack is configured to immerse one-third to one-half of the height of the battery cell in the coolant in response to the fire occurring in the at least one battery cell.

14. The battery pack according to any one of claims 8 to 13, characterized in that, The coolant is propylene glycol.

15. The battery pack according to any one of claims 8 to 13, characterized in that, The battery pack further includes a fire detection unit configured to detect an increase in temperature or generation of combustion gas in the plurality of battery cells.

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