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 priority to and the benefit of Korean Patent Application No. 10-2023-0094578, filed in the Korean Intellectual Property Office on July 20, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] An embodiment of the present disclosure relates 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 portion of the battery pack in the coolant. Background Art

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

[0005] Multiple battery cells can be arranged on a carrier plate. The carrier plate supports the weight of the battery cells and cools them. For example, a coolant can reduce the heat of the battery cells by absorbing heat from them while flowing along the carrier plate's flow path. However, if a fire occurs, a structure that only cools the lower portion of the battery cells is insufficient to prevent thermal runaway and heat propagation within the battery cells, potentially causing temperatures to rise to 1000°C.

[0006] The above information disclosed in the background of the present disclosure is only for improving understanding of the background of the disclosure and accordingly may contain information that does not constitute the relevant art. Summary of the Invention

[0007] An embodiment of the present disclosure relates 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 portion of the battery pack in the coolant.

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

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

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

[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 for Figure 3 Cross-sectional view of .

[0027] Figure 5 is a perspective view illustrating a battery pack according to yet another embodiment of the present disclosure. DETAILED DESCRIPTION

[0028] The embodiments of the present disclosure are provided to more completely describe the present disclosure to those skilled in the art. The following embodiments may be modified into various other forms, and the scope of the present disclosure is not limited to the following embodiments. Rather, 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 the convenience and clarity of description, the size (e.g., thickness) of each layer is 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 listed items. Further, the meaning of "connected" in this specification refers not only to the case where component A and component B are directly connected, but also 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, singular forms may include plural forms unless the context clearly indicates otherwise. Further, when used in this specification, "comprise" and / or "comprising" specify the presence of the features, numbers, steps, operations, components, elements and / or groups mentioned, and do not exclude the presence or addition of one or more other features, numbers, operations, components, elements and / or groups.

[0031] Although the terms "first," "second," and the like are used in this specification to describe various components, parts, regions, layers, and / or portions, it should be apparent that these components, parts, regions, layers, or portions should not be limited by these terms. These terms are merely 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] Spatially related terms (such as "below," "beneath," "below," "above," and "upper") are used to facilitate understanding of the relationship between one element or feature and another element or feature shown in the accompanying drawings. These spatially related terms are provided to facilitate understanding of 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 elements or features in the accompanying drawings are reversed, the elements described as "below" or "below" become "above" or "below." Accordingly, "below" is a concept that encompasses "above" or "below."

[0033] In the following, reference will be made to Figure 1 and Figure 2 A battery pack according to one embodiment of the present disclosure is described in detail.

[0034] Figure 1 FIG1 is an exploded perspective view illustrating a battery pack according to one embodiment of the present disclosure. Figure 2 is a simplified diagram illustrating the battery cells 110 and the upper cooling unit 200 during a fire that occurs in one of the battery cells 110 .

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

[0036] like Figure 1 As shown in , 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 support 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 rectangular parallelepiped shape. A plurality of battery cells 110 may be arranged in a row in one direction. In one or more embodiments, a plurality of battery cells 110 may be arranged so that the relatively wide plate surfaces of the battery cells 110 face each other. The battery cells 110 adjacent to each other may be arranged to be in close contact with each other. In one or more embodiments, an insulator of an organic material or an inorganic material may be between the battery cells 110 adjacent to each other to prevent heat propagation between the battery cells 110.

[0038] Each battery cell 110 may include a rectangular parallelepiped housing 111, an electrode assembly housed in the housing 111, and a cover plate 112 for sealing the opening of the housing 111. The electrode assembly is housed in the housing 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 housing 111 may be made of a metal (such as aluminum or stainless steel).

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

[0040] The uncoated area of ​​the positive electrode plate (positive electrode uncoated area) may 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) may 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 may be located on opposite side surfaces of the coated area. The positive electrode tab may be connected to the positive electrode uncoated area, and the negative electrode tab may be connected to the negative electrode uncoated area.

[0041] The cap plate 112 is coupled to the housing 111 and covers the opening of the housing 111. The cap plate 112 includes a positive electrode terminal 113 and a negative electrode terminal 114 that protrude to the outside and are electrically connected to the positive electrode plate and the negative electrode plate of the electrode assembly, respectively. Further, a vent hole 115 communicating with the interior of the housing 111 may be provided in the cap plate 112. A vent member including a recess configured to open by a preset pressure may be mounted on the vent hole 115.

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

[0043] The pair of end plates 120 are arranged to face the battery cells 110 at both ends among the plurality of battery cells 110. The pair of side plates 130 are orthogonally (or substantially orthogonally) coupled to the pair of end plates 120. Figure 1The pair of end plates 120 contacts the battery cells 110 at both ends and supports the plurality of battery cells 110 in the front-rear direction. The pair of side plates 130 supports the 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 the adjacent battery cells 110 may be electrically connected via the bus bars 140. Thus, since the plurality of battery cells 110 are electrically connected to each other, the battery pack may function as an electric power device. The bus bars 140 may be connected to the positive electrode terminals 113 and the negative electrode terminals 114 by any suitable method, such as welding.

[0045] The bus bar support 150 may be on the cover plate 112 and support the plurality of bus bars 140. The bus bar support 150 may include a plurality of through-holes through which the positive electrode terminal 113 and the negative electrode terminal 114 are exposed. Accordingly, the bus bars 140 may be electrically connected to the positive electrode terminal 113 and the negative electrode terminal 114. The bus bar support 150 may be made of an insulating material. The upper portion of the battery pack, excluding the bus bars 140 and the positive electrode terminal 113 and the negative electrode terminal 114, may be insulated by the bus bar support 150.

[0046] A circuit board 160 on which various circuits and components are mounted may 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 may be on the battery module 100. The coolant may be contained (e.g., filled or included) in the upper cooling unit 200. The lower cooling unit 300 may be below the battery module 100. The coolant may be contained (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 portions 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 portions of the battery module 100 when flowing through the internal flow paths of the upper cooling unit 200 and the lower cooling unit 300. Therefore, when the cooling unit is in contact with both the upper and lower portions of the battery module 100, the temperature imbalance problem in the battery cell 110 can be solved. That is, the temperature deviation in the battery cell 110 can be reduced, and accordingly, the current imbalance can be reduced, and the life of the battery cell 100 can be increased.

[0048] In the related art, only the lower part of the battery cell is cooled, so under fast charging conditions, an upper and lower temperature imbalance of about 23°C may occur in the battery cell. This upper and lower temperature imbalance leads to current imbalance and degradation of battery cell performance. For example, it is known that solid electrolyte interface (SEI) thermal decomposition occurs in the upper part and Li plating occurs in the lower part, which adversely affects the lifespan. Accordingly, uniform (or substantially uniform) temperature distribution of the battery cell solves both electrical and lifespan problems.

[0049] In one or more embodiments, a plurality of spray holes 220 may be provided 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 sprayed through the spray holes 220 corresponding to the battery cell 110 in which the fire occurred.

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

[0051] When no fire occurs in the battery cells 110, the plurality of spray holes 220 are closed. In response to a fire, the spray holes 220 corresponding to the battery cells 110 where the fire occurs are configured to open. The spray holes 220 may open due to the heat of the exhaust gas ejected or exhausted from the exhaust holes 115 of the battery cells 110 where the fire occurs.

[0052] Figure 2 The battery cells 110 and the upper cooling unit 200 are shown spaced apart from each other, and coolant is sprayed through one of the spray holes 220 corresponding to the battery cell 110 in which the fire occurred. In the illustrated embodiment, the spray hole 220 may be closed by a film 240. Depending on the embodiment, the film 240 may be coated on or adhered to the upper cooling unit 200 to block the spray hole 220. In one or more embodiments, the upper cooling unit 200 may include one or more plugs coupled to the spray hole 220.

[0053] In one or more embodiments, the film 240 is configured to melt due to 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 spray hole 220 may open, and the coolant in the upper cooling unit 200 may be sprayed through the spray hole 220 onto the exhaust hole 115 of the battery cell 110 where the fire 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, the upper cooling unit 200 can operate like a sprinkler and spray coolant onto the upper portion of the battery cell 110 to immediately (or substantially immediately) extinguish the fire in the battery cell 110. Accordingly, heat propagation to other battery cells 110 adjacent to the battery cell 110 where the fire occurred can be suppressed. That is, because the fire can be extinguished immediately (or substantially immediately) and heat propagation can be prevented even when the battery cell 110 reaches thermal runaway, the safety of the battery pack can be improved.

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

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

[0057] Now refer to Figure 3 and Figure 4 A battery pack according to another embodiment of the present disclosure is described.

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

[0059] A battery pack according to another embodiment of the present disclosure 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 those described above, and Figure 3 and Figure 4 The upper cooling unit 200 is omitted. Hereinafter, the description will focus on the structure in which the housing 400 and a portion of the battery module 100 are immersed in the coolant in response to the occurrence of a fire.

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

[0061] The position of the battery module 100 can be fixed in the housing 400 by fixing the battery module 100 to the support member 460 by fastening (eg, screwing) and / or laser welding. Figure 4 In the embodiment shown in FIG, the battery module 100 may be spaced apart from the bottom surface of the housing 400 by a predetermined 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 predetermined height h may have the same (or substantially the same) value 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., when no fire occurs in the battery cell 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 be in contact with at least the bottom surface of the battery module 100 (e.g., a 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, because 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-described embodiment may be replaced by a bottom plate for supporting a 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, a coolant is introduced into the housing 400 through the coolant inlet 420. Accordingly, the battery module 100 may 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 may 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 may be immersed in the coolant may be maintained.

[0064] In this embodiment, since the lower portion of the battery module 100 is immersed in 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 portions of the battery module 100 can be cooled. Furthermore, when a fire occurs, the upper cooling unit 200 can function as a sprinkler.

[0065] In response to a fire occurring in one or more battery cells 110, coolant is sprayed from above, and a portion of the battery module 100 is immersed in the coolant, thereby enabling the fire to be extinguished immediately (or substantially immediately). Furthermore, heat propagation to other battery cells 110 adjacent to the battery cell 110 where the fire occurred can be suppressed. That is, because the fire can be extinguished immediately (or substantially immediately) and heat propagation can be prevented even when a battery cell 110 reaches thermal runaway, the safety of the battery pack can be improved.

[0066] Furthermore, in one or more embodiments, only the lower portion of the battery module 100 is immersed in the coolant, thereby allowing the busbars 140 and circuit board 160 located above the battery module 100 to be separated from the coolant. Furthermore, because only a portion of the battery module 100 is immersed in the coolant, the height of the housing 400 does not need to be higher than that of the battery module 100. Consequently, the weight of the housing 400 and the coolant can be reduced, thereby reducing the overall weight of the battery pack.

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

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

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

[0070] Will refer to Figure 5 A battery pack according to still another embodiment of the present disclosure is described in detail.

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

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

[0073] The housing 400 has Figure 4 , and the battery module 100 can be accommodated 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 supports 460 and spaced apart from the bottom surface of the housing 400 by a preset height h. Accordingly, because 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. Because 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 can be replaced by a base 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 greater than that of the battery module 100. Accordingly, 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, and thus the entire battery module 100 may be immersed in the coolant (e.g., the entire height of the battery module 100 may be immersed in the coolant). However, the present disclosure is not limited thereto, and even when a fire does not occur, the entire battery module 100 may be immersed in the coolant.

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

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

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

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

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

[0080] According to embodiments of the present disclosure, in response to a fire in a battery pack, coolant can be sprayed onto the battery pack from above, acting as a sprinkler. In one or more embodiments, by immersing at least a portion of the battery pack in the coolant, the fire can be extinguished and heat spread can be suppressed. This improves the safety of the battery pack because the fire can be immediately extinguished and heat spread can be prevented even when a battery cell reaches thermal runaway.

[0081] Furthermore, when the coolant contacts the upper and lower parts 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 life of the battery cells can be increased.

[0082] Further, propylene glycol can serve as a coolant for the battery cells when no fire occurs, and can serve as a fire extinguishing agent when a fire occurs, so it is effective and harmless to the human body.

[0083] The above description is merely some embodiments for implementing the present disclosure, and the present disclosure is not limited to the above embodiments, and 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 main purpose of the present disclosure.

Claims

1. A battery pack comprising: A plurality of battery cells including a plurality of vent holes; an upper cooling unit, on the battery cell, the upper cooling unit comprising a coolant and a plurality of spray holes; as well as a lower cooling unit in contact with lower portions of the plurality of battery cells, the lower cooling unit comprising the coolant, wherein the plurality of spray holes in the upper cooling unit correspond to the plurality of exhaust holes of the plurality of battery cells, and wherein the upper cooling unit is configured to spray the coolant through at least one spray hole among the plurality of spray holes corresponding to the at least one battery cell 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 greater than a diameter of the plurality of exhaust holes. 4 . The battery pack according to claim 2 , wherein the spray hole is configured to open in response to the fire occurring in a corresponding battery cell among the plurality of battery cells. 5 . The battery pack according to claim 4 , wherein the spray hole is configured to open in response to heat of exhaust gas sprayed from the exhaust hole located in the corresponding battery cell where the fire occurs among the plurality of exhaust holes.

6. The battery pack according to any one of claims 1 to 5, wherein the coolant is propylene glycol. 7 . The battery pack according to claim 1 , further comprising a fire detection unit configured to detect a temperature increase or generation of a combustion gas of at least one of the plurality of battery cells.

8. A battery pack comprising: Multiple battery cells; A housing for accommodating the plurality of battery cells; a coolant inlet in a side surface of the housing; as well as A coolant outlet, in the other side surface of the housing, The battery pack is configured to introduce a 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 , wherein the plurality of battery cells are spaced apart from a bottom surface of the case by a preset height.

10. The battery pack according to claim 9, wherein when the fire does not occur in the plurality of battery cells, the coolant is filled in the case to a preset height from the bottom surface of the case, and wherein the coolant contacts the bottom surfaces of the plurality of battery cells. 11 . The battery pack according to claim 9 , wherein the preset height is the same as a thickness of one of the plurality of battery cells along a direction in which the plurality of battery cells are arranged.

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, wherein the coolant is propylene glycol. 15 . The battery pack according to claim 8 , further comprising a fire detection unit configured to detect a temperature increase or generation of a combustion gas of the plurality of battery cells.

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