Battery pack with improved cooling performance

Abstract

The disclosed invention relates to a battery pack, and in one example includes a pack case, a plurality of batteries housed inside the pack case, a heat sink located above the batteries and storing cooling water, a plurality of supply passages that respectively connect the heat sink to the plurality of batteries, and a plurality of plugs that respectively seal the plurality of supply passages and are melted by heat generated in the event of thermal runaway of the batteries.

Description

[Technical Field]

[0001] The present invention relates to a battery pack, and more particularly to a battery pack that can effectively suppress a heat propagation phenomenon in which, when a thermal runaway phenomenon occurs in a secondary battery, other surrounding secondary batteries are continuously overheated.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0053370, filed on April 29, 2022, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference. [Background technology]

[0003] Unlike primary batteries, secondary batteries are rechargeable and have the potential to be small and have large capacities, which has led to extensive research and development in recent years. Demand for secondary batteries as an energy source is rapidly increasing due to the increasing technological development and demand for mobile devices, as well as the emergence of electric vehicles and energy storage systems in response to modern demands for environmental protection.

[0004] Secondary batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries depending on the shape of the battery case. The electrode assembly installed inside the battery case of a secondary battery is a power generating element that can be charged and discharged and is made up of a laminated structure of electrodes and a separator.

[0005] Since secondary batteries are required to be used continuously for long periods of time, it is necessary to effectively control the heat generated during the charging and discharging process.If secondary batteries are not cooled smoothly, a positive feedback chain reaction will occur in which a rise in temperature causes an increase in current, and the increase in current causes another rise in temperature, ultimately leading to a catastrophic state of thermal runaway.

[0006] In addition, when secondary batteries are grouped together in the form of a module or pack, thermal runaway in one secondary battery can cause thermal propagation, in which other surrounding secondary batteries are continuously overheated.Furthermore, there is a high risk of fire due to ignition sources such as flammable gases emitted from overheated secondary batteries and heating electrodes, so it is necessary to prevent this risk of fire. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent Publication No. 10-2017-0070542 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a battery pack that can effectively suppress and prevent the heat propagation phenomenon caused by thermal runaway occurring in a secondary battery.

[0009] However, the technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0010] The present invention relates to a battery pack, which in one example includes a pack case, a plurality of batteries housed inside the pack case, a heat sink located above the batteries and storing cooling water, a plurality of supply passages that respectively connect the heat sink and the plurality of batteries, and a plurality of plugs that respectively seal the plurality of supply passages and are melted by heat generated in the event of thermal runaway of the batteries.

[0011] In one embodiment of the present invention, the battery includes a case made of a metal material and having a water inlet communicating with the supply passage, a plurality of battery cells housed in the case, and a heat sink disposed between the plurality of battery cells.

[0012] The heat absorber includes an absorbent material impregnated with a liquid that absorbs heat generated in the battery cell and vaporizes, and an exterior material that houses the absorbent material.

[0013] According to one embodiment of the present invention, the outer packaging material may be a thermally conductive pouch, and the pouch may be provided with a weakened portion that preferentially ruptures when the liquid impregnated in the absorbent material evaporates and the internal pressure increases.

[0014] Here, the absorbent material can be a superabsorbent matrix containing superabsorbent polymers (SAP) or superabsorbent fibers (SAF).

[0015] The plug can be melted before the weakened portion of the pouch breaks, and the water inlet can be open toward the heat absorber.

[0016] A heat insulating material may be disposed between the plurality of batteries.

[0017] Meanwhile, according to another embodiment of the present invention, the heat sink includes a first block and a second block that are independent of each other, the plurality of supply passages include a first supply passage that connects the first block and the plurality of batteries, respectively, and a second supply passage that connects the second block and the plurality of batteries, the plurality of plugs include a first plug that seals the first supply passage, respectively, and a second plug that seals the second supply passage, respectively, and the melting points of the first plugs and the second plugs may be different from each other.

[0018] Here, the liquid stored in the first block may be water, and the melting point of the first plug may be lower than the melting point of the second plug.

[0019] The first plug may be melted before the weakened portion of the pouch breaks.

[0020] The liquid stored in the second block is water mixed with an additive, and the additive may be a substance that reduces the surface tension of water or a fire extinguishing agent.

[0021] The second plug may be melted after the weakened portion of the pouch is ruptured.

[0022] The water inlet may include a first water inlet communicating with the first supply passage and a second water inlet communicating with the second supply passage, and the first water inlet may be open toward the heat absorber. [Effects of the Invention]

[0023] According to the battery pack of the present invention having the above-described configuration, the heat sink disposed outside the battery and the heat absorber disposed inside the battery quickly absorb and dissipate heat in an environment where temperature rises frequently, such as during rapid charging, thereby suppressing the occurrence of thermal runaway and maintaining performance and lifespan without a high temperature rise.

[0024] Furthermore, in the present invention, when the battery overheats, the low-melting-point plug that seals the cooling water stored inside the heat sink melts and supplies water to the heat absorber inside the battery case, thereby delaying the rupture of the heat absorber that absorbs the heat of the battery and absorbing the heat of the battery for a longer period of time, thereby suppressing the occurrence of thermal runaway.

[0025] In addition, when thermal runaway occurs in the battery and the risk of a fire increases, the battery pack of the present invention can effectively reduce the risk of a fire caused by a high-temperature ignition source by discharging water containing a functional additive.

[0026] However, the technical effects that can be obtained by the present invention are not limited to the effects described above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Brief explanation of the drawings]

[0027] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention, and therefore the present invention should not be interpreted as being limited solely to the matters depicted in such drawings. [Figure 1] 1 is an exploded perspective view of a battery pack according to an embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional view taken along the line "AA" in FIG. [Figure 3] 1 is a diagram illustrating a heat sink disposed between battery cells housed in a case. [Figure 4] 1 is a diagram illustrating a state in which coolant stored in a heat sink is poured into the battery; [Figure 5] 10 is a view illustrating a heat sink provided in a battery pack according to another embodiment of the present invention. [Figure 6] 6 is a diagram illustrating a coupling structure between the heat sink and the battery in FIG. 5. [Figure 7] 10 is a diagram illustrating a state in which the second plug is melted and the liquid stored in the heat sink is injected into the battery. DETAILED DESCRIPTION OF THE INVENTION

[0028] Because the present invention can be modified in various ways and can have various embodiments, specific embodiments will be described in detail below.

[0029] However, this is not intended to limit the invention to any particular embodiment, but should be understood to include all modifications, equivalents, or alternatives falling within the spirit and scope of the invention.

[0030] In the present invention, the terms "comprise" and "have" are intended to specify the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification, and should be understood as not precluding the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0031] Furthermore, in the present invention, when a layer, film, region, plate, or other portion is described as being "on" another portion, this includes not only the case where it is "directly on" the other portion, but also the case where there is another portion therebetween. Conversely, when a layer, film, region, plate, or other portion is described as being "under" the other portion, this includes not only the case where it is "directly under" the other portion, but also the case where there is another portion therebetween. Furthermore, in this application, being "located on" can include not only the case where it is located at the top, but also the case where it is located at the bottom.

[0032] The present invention relates to a battery pack, and in one example, the battery pack of the present invention includes a pack case, a plurality of batteries housed inside the pack case, a heat sink located above the batteries and storing coolant, a plurality of supply passages that respectively connect the heat sink and the plurality of batteries, and a plurality of plugs that respectively seal the plurality of supply passages and are melted by heat generated during thermal runaway of the batteries.

[0033] In one embodiment of the present invention, the battery includes a case made of a metal material and having a water inlet communicating with the supply passage, a plurality of battery cells housed in the case, and a heat sink disposed between the plurality of battery cells.

[0034] In the battery pack of the present invention, the heat sink disposed outside the battery and the heat absorber inside the battery quickly absorb and dissipate heat in an environment where temperature rises frequently, such as during fast charging, thereby suppressing the occurrence of thermal runaway and maintaining performance and lifespan without a high temperature rise.

[0035] Furthermore, in the present invention, when the battery overheats, the low-melting-point plug that seals the cooling water stored inside the heat sink melts and supplies water to the heat absorber inside the battery case, thereby delaying the rupture of the heat absorber that absorbs the heat of the battery and absorbing the heat of the battery for a longer period of time, thereby suppressing the occurrence of thermal runaway.

[0036] Hereinafter, specific embodiments of the battery pack 10 of the present invention will be described in detail with reference to the accompanying drawings. For reference, the directions of front, back, up, down, left, and right used in the following description to designate relative positions are intended to facilitate understanding of the invention, and unless otherwise specified, are based on the directions shown in the drawings.

[0037] (First embodiment) FIG. 1 is an exploded perspective view of a battery pack 10 according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line "AA" in FIG.

[0038] As shown in the drawings, a battery pack 10 of the present invention includes a pack case 100 and a plurality of batteries 200 housed within the pack case 100. The pack case 100 is made up of a main case 110 with a U-shaped cross section, a top case 120 coupled to the open side of the main case 110, and a pair of side cases 130. The battery 200 is a prismatic secondary battery, and is exemplified as a one-way secondary battery in which both positive and negative electrode terminals are arranged on the top surface.

[0039] A heat sink 300 is provided inside the pack case 100 and disposed above the battery 200. That is, the heat sink 300 is disposed between the top case 120 of the pack case 100 and the top surface of the battery 200. The heat sink 300 stores coolant therein to absorb heat generated by the battery 200. For reference, although the first embodiment of the present invention has been described as a structure in which coolant is stored in the heat sink 300, a modified embodiment may also be implemented as a structure in which coolant supplied from the outside is circulated through the heat sink 300 and then discharged.

[0040] A plurality of supply passages 330 are provided between the heat sink 300 and the plurality of batteries 200 to allow them to communicate with each other. The number of supply passages 330 is at least equal to the number of batteries 200, and all of the batteries 200 are connected to the heat sink 300. The supply passages 330 may be provided as a separate member, for example, a plate having the supply passages 330 formed therein, or may be integrally formed on the bottom surface of the heat sink 300. In the illustrated first embodiment, the supply passages 330 are provided in the form of holes penetrating the bottom surface of the heat sink 300.

[0041] A plug 340 is coupled to each of the supply passages 330 to seal the coolant in the heat sink 300. The plug 340 is made of a material that melts at a predetermined temperature. For example, the plug 340 may be made of a material that melts at a temperature of about 100°C. As a result, the plug 340 that seals the supply passage 330 melts due to heat generated when the battery 200 experiences thermal runaway, and as the plug 340 melts, the coolant in the heat sink 300 is discharged downward toward the battery 200.

[0042] The coolant discharged from the heat sink 300 cools the overheated battery 200, and to enhance this cooling effect, the battery pack 10 of the present invention is configured to inject coolant directly into the battery 200. To this end, the battery 200 includes a metal case 210 having a water inlet 212 communicating with a supply passage 330, a plurality of battery cells 220 housed in the case 210, and a heat sink 230 disposed between the plurality of battery cells 220.

[0043] Here, the battery cells 220 housed in the case 210 are pouch cells, and the electrode assemblies and electrolyte are sealed within the pouch cells. Therefore, even if cooling water is poured directly into the inside of the case 210, it does not affect the operation of the battery cells 220. In fact, the cooling water directly contacting the outer surfaces of the battery cells 220 greatly increases the cooling effect of the battery 200.

[0044] In the illustrated embodiment, two battery cells 220 are housed in the case 210, and a heat absorber 230 is disposed between the battery cells 220. The heat absorber 230 serves to absorb heat generated by the battery cells 220.

[0045] In the first embodiment of the present invention, the heat absorber 230 includes an absorbent material 236 impregnated with a liquid that absorbs and vaporizes heat generated in the battery cell 220, and an exterior material 232 that houses the absorbent material 236 that has absorbed and stored the liquid. If the heat absorber 230 is configured with the absorbent material 236 impregnated with the liquid, it can be installed inside the case 210 without the risk of liquid leakage.

[0046] In the present invention, to enhance the performance of the heat sink 230, the liquid-impregnated absorbent material 236 may be constructed of a super absorbent matrix including a super absorbent polymer (SAP) or a super absorbent fiber (SAF).

[0047] A highly absorbent matrix is ​​porous or fibrous and can absorb large amounts of liquid by exhibiting capillary action, and highly absorbent fibers can be produced by processing highly absorbent resins into fibers such as nonwoven fabrics.

[0048] In the present invention, the specific types of superabsorbent resin and the superabsorbent fiber produced therefrom are not particularly limited, and any resin having excellent absorption capacity for fluids, particularly water, can be used without limitation. Examples of superabsorbent resins in the present invention include polyacrylic acid, polyacrylates, polyacrylate graft polymers, starch, crosslinked carboxymethyl cellulose, acrylic acid copolymers, hydrolyzed starch-acrylonitrile graft copolymers, starch-acrylic acid graft copolymers, saponified vinyl acetate-acrylic acid ester copolymers, hydrolyzed acrylonitrile copolymers, hydrolyzed acrylamide copolymers, ethylene-maleic anhydride copolymers, isobutylene-maleic anhydride copolymers, polyvinyl sulfonic acid, polyvinyl phosphonic acid, polyvinyl phosphoric acid, polyvinyl sulfuric acid, sulfuric acid, and the like. Examples of the crosslinking agent include one or more selected from the group consisting of substituted polystyrene, polyvinylamine, polydialkylaminoalkyl(meth)acrylamide, polyethyleneimine, polyallylamine, polyallylguanidine, polydimethyldiallylammonium hydroxide, quaternized polystyrene derivatives, guanidine-modified polystyrene, quaternized poly(meth)acrylamide, polyvinylguanidine, and mixtures thereof, and preferably include one or more selected from the group consisting of crosslinked polyacrylates, crosslinked polyacrylic acids, and crosslinked acrylic acid copolymers, but are not limited to these.

[0049] In the present invention, the type of acrylic acid copolymer used as the superabsorbent resin is not particularly limited, but it may be a copolymer containing an acrylic acid monomer and one or more comonomers selected from the group consisting of maleic acid, itaconic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, 2-(meth)acryloylethanesulfonic acid, 2-hydroxyethyl (meth)acrylate, and styrenesulfonic acid.

[0050] In the present invention, the superabsorbent resin can have a water absorption capacity of 10 g / g to 500 g / g, preferably 50 g / g to 200 g / g, but is not limited thereto. That is, 1 g of the superabsorbent resin can absorb 10 g to 500 g of water, preferably 50 g to 200 g of water.

[0051] In the present invention, the greater the water absorption capacity of the superabsorbent resin, the longer the cooling effect can last. However, if the water absorption capacity exceeds 500 g / g, the fluidity of the superabsorbent resin increases and it becomes difficult to maintain its shape, making it impossible to provide effective cooling. If the water absorption capacity is less than 10 g / g, the cooling effect will last too long and may be inefficient.

[0052] In the first embodiment of the present invention, the outer casing 232 of the heat absorber 230 may be a thermally conductive pouch 232', and the pouch 232' may be provided with a fragile portion 234 that breaks preferentially when the liquid impregnated in the absorbent material 236 evaporates and the internal pressure increases.

[0053] The liquid impregnated in the absorbent material 236 absorbs the heat generated in the battery cells 220 and vaporizes when its temperature exceeds its boiling point. The increase in volume caused by the phase change from liquid to gas causes internal pressure to act on the pouch 232' that seals the absorbent material 236.

[0054] Here, the pouch 232' has a weakened portion 234 that breaks preferentially when the liquid impregnated in the absorbent material 236 evaporates and the internal pressure increases. The pouch 232', which is the outer packaging material 232, can be manufactured using a flexible laminate sheet.

[0055] The laminate sheet may have a three-layer or more structure including an aluminum thin film layer, an inner resin layer formed inside the aluminum thin film layer, and an outer resin layer formed outside the aluminum thin film layer. For example, the inner resin layer may be cast polypropylene (CPP) or polypropylene (PP), and the outer resin layer may be polyethylene terephthalate (PET) or nylon.

[0056] The weakened portion 234 of the pouch 232' locally reduces the sealing strength of the pouch 232', so that it will preferentially rupture due to the increase in internal pressure caused by evaporation of the liquid. The pouch 232' is sealed by heat sealing the edges of the laminate sheet encasing the absorbent material 236, and the weakened portion 234 may be formed in a manner that intentionally reduces the heat seal strength compared to the surrounding area. For example, the weakened portion 234 may be formed by making the pouch thinner than the surrounding area, by forming a notch to reduce strength, or by locally removing an aluminum thin film layer that maintains durability.

[0057] Due to the presence of the fragile portion 234 in the pouch 232', if the battery cell 220 experiences thermal runaway and overheats, the liquid impregnated in the absorbent material 236 inside the pouch 232' absorbs the heat and vaporizes. When the internal pressure of the vaporized gas rises above a certain level, the fragile portion 234 of the pouch 232' ruptures, releasing the gas. The gas released from the heat absorber 230 cools flammable gases and ignition sources such as heating electrodes emitted from the overheated battery cell 220, suppressing the flames and significantly reducing the risk of fire.

[0058] In one embodiment of the present invention, the liquid impregnated in the absorbent material 236 may be water. Water has the highest specific heat and latent heat among readily available liquids. Therefore, water contained in the absorbent material 236 is suitable for use in the heat absorber 230 because it absorbs a large amount of heat during the process of changing phase from pre-vaporization to gas.

[0059] In this way, the pouch 232' having the fragile portion 234 can provide rapid cooling and even fire extinguishing effects in emergency situations where high temperatures persist. However, if the heat absorber 230 breaks and the accumulated gas suddenly escapes, the heat absorber 230 will lose most of its function. Therefore, for the safety of the battery 200 and the battery pack 10, it is preferable that the heat absorption function of the heat absorber 230 be maintained for as long as possible.

[0060] To this end, the battery pack 10 of the present invention may be configured so that the plug 340 that closes the supply passage 330 between the heat sink 300 and the water inlet 212 melts before the fragile portion 234 of the pouch 232′ breaks. For example, if the liquid inside the heat absorber 230 is water, the plug 340 may be designed to melt at a temperature of about 90°C to 100°C, before the water completely boils, so that the cooling water in the heat sink 300 can cool the pouch 232′.

[0061] The cooling of the pouch 232' delays the boiling of the liquid, and therefore the time until the heat absorber 230 breaks and loses its function is delayed. That is, the cooling water in the heat sink 300 cools the battery cells 220 and the heat absorber 230 at the same time, which effectively delays the breakdown of the battery cells 220 that can no longer control thermal runaway.

[0062] To quickly cool the battery cells 220 and the heat sinks 230 disposed therebetween, the water inlet 212 provided on the case 210 may be positioned so as to open toward the heat sink 230. Furthermore, by disposing a heat insulating material 400, such as mica, between the multiple batteries 200, blocking heat transfer between adjacent batteries 200 may be advantageous in preventing thermal runaway from spreading to the surrounding area, i.e., preventing heat propagation. Furthermore, a cooling pad 410 similar to the heat sink 300 may be provided on the bottom of the pack case 100 to enhance cooling of the battery 200.

[0063] (Second embodiment) FIG. 5 is a view illustrating a heat sink 300 provided in a battery pack 10 according to a second embodiment of the present invention, and FIG. 6 is a view illustrating a coupling structure between the heat sink 300 and the battery 200 of FIG. 5.

[0064] The second embodiment of the present invention differs from the first embodiment described above in the configurations of the heat sink 300, the supply passage 330, and the plug 340. The following description will focus on the characteristic configuration of the second embodiment, and a detailed description of the configuration that overlaps with the first embodiment will be omitted.

[0065] In the second embodiment of the present invention, the heat sink 300 includes a first block 310 and a second block 320 that are independent from each other. That is, the interior of the heat sink 300 is divided into two regions that are separated from each other. The plurality of supply passages 330 that communicate with the interior of the battery 200 include first supply passages 331 that communicate the first block 310 with each of the plurality of batteries 200, and second supply passages 332 that communicate the second block 320 with each of the plurality of batteries 200.

[0066] The plurality of plugs 340 include first plugs 341 that seal the first supply passages 331, respectively, and second plugs 342 that seal the second supply passages 332, respectively, and the melting points of the first plugs 341 and the second plugs 342 are different from each other.

[0067] Here, the liquids stored in the first block 310 and the second block 320 of the heat sink 300 may be different from each other. For example, as in the first embodiment described above, the liquid stored in the first block 310 is water, and the melting point of the first plug 341 is lower than the melting point of the second plug 342. In addition, the first plug 341 melts before the fragile portion 234 of the pouch 232' breaks. As a result, the water discharged from the first block 310 by the melting of the first plug 341 cools the pouch 232', thereby prolonging the operation of the heat absorber 230.

[0068] In contrast, the liquid stored in the second block 320 is water mixed with an additive, which can be a substance that reduces the surface tension of the water or a fire-extinguishing agent. Such additives are intended to enhance the fire-extinguishing properties of the water. Examples of substances that reduce the surface tension of water include wetting agents and surfactants. Lowering the surface tension of water increases the penetration effect of the water, thereby enhancing the fire-extinguishing effect against ignition sources such as heating electrodes and ignition particles.

[0069] A fire extinguishing agent is a general term for an agent that itself exhibits fire extinguishing properties, and various commercially available powder fire extinguishing agents and liquid fire extinguishing agents can be used. For example, a fire extinguishing agent with the product name F-500 EA (manufacturer: HAZARD CONTROL TECHNOLOGIES, INC.) can be added to water.

[0070] 7 is a diagram illustrating a state in which the second plug 342 melts and the liquid stored in the heat sink 300 is injected into the battery 200. The melting point of the second plug 342 is higher than that of the first plug 341, and it is particularly preferable that the second plug 342 melts after the fragile portion 234 of the pouch 232′ is ruptured. For example, the second plug 342 may be made of a material that melts at the temperature of the superheated steam that is generated inside the heat absorber 230 and then ejected when the fragile portion 234 is ruptured.

[0071] The situation in which the weak portion 234 of the heat absorber 230 breaks is when the water supplied from the first block 310 can no longer cool the heat absorber 230 and a high-temperature atmosphere persists in which the vapor pressure inside the heat absorber 230 reaches its limit, and the battery cell 220 is likely to burn or explode in such a high-temperature atmosphere.

[0072] Therefore, in order to respond to such an emergency situation, the second block 320 stores water mixed with an additive, and the second plug 342 melts after the fragile portion 234 of the pouch 232' breaks, thereby extinguishing a fire that may occur after the heat absorber 230 loses its function, in the second embodiment of the present invention.

[0073] As in the first embodiment, the water inlet 212 of the battery 200 includes a first water inlet 213 communicating with the first supply passage 331 and a second water inlet 214 communicating with the second supply passage 332, and the first water inlet 213 opens toward the heat absorber 230 to quickly cool the heat absorber 230. There is relatively little need for the second water inlet 214 to open toward the heat absorber 230, and it is preferable for the second water inlet 214 to open toward the battery cell 220 for effective fire extinguishing.

[0074] The present invention has been described in more detail above with reference to the drawings and embodiments, etc. However, the configurations described in the drawings or embodiments in this specification are merely one embodiment of the present invention and do not represent all of the technical ideas of the present invention, so it should be understood that there may be various equivalents and modifications that can replace them at the time of filing this application. [Explanation of symbols]

[0075] 10: Battery pack 100: Pack case 110: Main case 120: Top case 130: Side case 200: Battery 210: Case 212: Water inlet 213: 1st water inlet 214:Second water inlet 220: Battery cell 230: Heat absorber 232: Exterior materials 232': Pouch 234: Weak part 236: Absorbent material 300: Heat sink 310: Block 1 320: Second Block 330: Supply passage 331: 1st supply passage 332:Second supply passage 340: Plug 341: First plug 342: Second plug 400:Insulation 410: Cooling pad

Claims

1. Pack case and a plurality of batteries housed inside the pack case; a heat sink located above the battery and storing cooling water; a plurality of supply passages respectively communicating the heat sink with the plurality of batteries; a plurality of plugs that seal the plurality of supply passages, respectively, and that are melted by heat generated in the event of thermal runaway of the battery; Including, The battery a case made of a metal material and having a water inlet communicating with the supply passage; a plurality of battery cells housed inside the case; a heat sink disposed between the plurality of battery cells; Including, The heat absorber is an absorbent material impregnated with a liquid that vaporizes by absorbing heat generated in the battery cell; an exterior material that houses the absorbent material; Including, the outer packaging material is a thermally conductive pouch, the pouch has a fragile part that breaks preferentially when the internal pressure increases due to evaporation of the liquid impregnated in the absorbent material, The plug is melted before the weakened portion of the pouch ruptures.

2. The battery pack according to claim 1 , wherein the water inlet is open toward the heat sink.

3. Pack case and a plurality of batteries housed inside the pack case; a heat sink located above the battery and storing cooling water; a plurality of supply passages respectively communicating the heat sink with the plurality of batteries; a plurality of plugs that seal the plurality of supply passages, respectively, and that are melted by heat generated in the event of thermal runaway of the battery; Including, The battery a case made of a metal material and having a water inlet communicating with the supply passage; a plurality of battery cells housed inside the case; a heat sink disposed between the plurality of battery cells; Including, The heat absorber is an absorbent material impregnated with a liquid that vaporizes by absorbing heat generated in the battery cell; an exterior material that houses the absorbent material; Including, the outer packaging material is a thermally conductive pouch, the pouch has a fragile part that breaks preferentially when the internal pressure increases due to evaporation of the liquid impregnated in the absorbent material, the heat sink includes a first block and a second block that are independent of each other; the plurality of supply passages include a first supply passage that connects the first block with each of the plurality of batteries, and a second supply passage that connects the second block with each of the plurality of batteries, the plurality of plugs include first plugs that seal the first supply passages, respectively, and second plugs that seal the second supply passages, respectively; The melting point of the first plug and the melting point of the second plug are different from each other.

4. the liquid stored in the first block is water; The battery pack according to claim 3 , wherein a melting point of the first plug is lower than a melting point of the second plug.

5. The battery pack according to claim 3 , wherein the first plug is melted before the weakened portion of the pouch ruptures.

6. The liquid stored in the second block is water mixed with an additive, The battery pack according to claim 3 , wherein the additive is a substance that reduces the surface tension of water or a fire extinguishing agent.

7. The battery pack according to claim 6 , wherein the second plug is melted after the weakened portion of the pouch is ruptured.

8. the water inlet includes a first water inlet communicating with the first supply passage and a second water inlet communicating with the second supply passage; The battery pack according to claim 3 , wherein the first water inlet is open toward the heat sink.

9. A battery pack as described in claim 1, wherein the absorbent material is a highly absorbent matrix comprising a highly absorbent polymer or highly absorbent fiber.

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