BATTERY PACK INCLUDING THERMAL SPREAD INHIBITION STRUCTURE

Abstract

A battery pack includes a battery pack case configured to receive one or more battery modules and a heat sink located above the battery modules, wherein each of the battery modules includes a plurality of battery cells, a water tank located above the plurality of battery cells, and a module case configured to receive the plurality of battery cells and the water tank, whereby, when fire breaks out in the battery cell, it is possible to rapidly and accurately prevent spread of flames of the ignited battery cell.

Claims

1. A battery pack comprising: a battery pack case configured to receive at least one battery module; and a heat sink located above the at least one battery module, wherein the at least one battery module comprises: a plurality of battery cells; a water tank located above the plurality of battery cells; and a module case configured to receive the plurality of battery cells and the water tank.

2. The battery pack according to claim 1, wherein the water tank is mounted integrally to an inside of an upper surface of the module case.

3. The battery pack according to claim 1, wherein an upper part of the module case is open, and wherein the water tank is coupled to the module case so as to cover the open upper part of the module case.

4. The battery pack according to claim 1, wherein the heat sink is configured to have a size that covers all of an upper surface of the at least one battery module.

5. The battery pack according to claim 1, wherein an upper part of the battery pack case is open, and wherein the heat sink is coupled to the battery pack case so as to cover the open upper part of the battery pack case.

6. The battery pack according to claim 1, wherein a through-hole is formed in a first surface of the water tank that faces the plurality of battery cells, and wherein a sealing member is added to the through-hole.

7. The battery pack according to claim 6, wherein the sealing member is made of a material that is melted by high-temperature gas or sparks discharged from a first battery cell of the plurality of battery cells.

8. The battery pack according to claim 7, wherein the through-hole is opened as a result of melting of the sealing member, and wherein a coolant received in the water tank is introduced into the first battery cell through the through-hole.

9. The battery pack according to claim 6, wherein the through-hole is configured to have a plurality of holes in the first surface of the water tank so as to be uniformly dispersed.

10. The battery pack according to claim 1, wherein a flow path configured to guide flow of a coolant is formed in the heat sink.

11. The battery pack according to claim 1, wherein the at least one battery module is a plurality of battery modules, and wherein a partition wall is added between the plurality of battery modules.

12. The battery pack according to claim 6, wherein the through-hole is filled with the sealing member, and wherein the sealing member comprises an extension portion having a width greater than a circumference of the through-hole.

13. The battery pack according to claim 1, wherein each of the plurality of battery cells is a pouch-shaped battery cell, a prismatic battery cell, or a cylindrical battery cell.

Description

DESCRIPTION OF DRAWINGS

[0040] FIG. 1 is a perspective view of a battery pack according to a first embodiment of the present invention.

[0041] FIG. 2 is an exploded perspective view of the battery pack according to the first embodiment.

[0042] FIG. 3 is a sectional view of the battery pack taken along line A-A′ of FIG. 1.

[0043] FIG. 4 is a schematic view illustrating a situation in which flames are extinguished when fire breaks out in the battery pack according to the first embodiment.

[0044] FIG. 5 is an exploded perspective view of a battery pack according to a second embodiment.

[0045] FIG. 6 is a sectional view of the battery pack according to the second embodiment.

[0046] FIG. 7 is a schematic view illustrating a situation in which flames are extinguished when fire breaks out in the battery pack according to the second embodiment.

[0047] FIG. 8 is an exploded perspective view of a battery pack according to a third embodiment.

[0048] FIG. 9 is a sectional view of the battery pack according to the third embodiment.

[0049] FIG. 10 is a schematic view illustrating a situation in which flames are extinguished when fire breaks out in the battery pack according to the third embodiment.

BEST MODE

[0050] Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that the preferred embodiments of the present invention can be easily implemented by a person having ordinary skill in the art to which the present invention pertains. In describing the principle of operation of the preferred embodiments of the present invention in detail, however, a detailed description of known functions and configurations incorporated herein will be omitted when the same may obscure the subject matter of the present invention.

[0051] In addition, the same reference numbers will be used throughout the drawings to refer to parts that perform similar functions or operations. In the case in which one part is said to be connected to another part throughout the specification, not only may the one part be directly connected to the other part, but also, the one part may be indirectly connected to the other part via a further part. In addition, that a certain element is included does not mean that other elements are excluded, but means that such elements may be further included unless mentioned otherwise.

[0052] In addition, a description to embody elements through limitation or addition may be applied to all inventions, unless particularly restricted, and does not limit a specific invention.

[0053] Also, in the description of the invention and the claims of the present application, singular forms are intended to include plural forms unless mentioned otherwise.

[0054] Also, in the description of the invention and the claims of the present application, “or” includes “and” unless mentioned otherwise. Therefore, “including A or B” means three cases, namely, the case including A, the case including B, and the case including A and B.

[0055] In addition, all numeric ranges include the lowest value, the highest value, and all intermediate values therebetween unless the context clearly indicates otherwise.

[0056] Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0057] FIG. 1 is a perspective view of a battery pack according to a first embodiment of the present invention, and FIG. 2 is an exploded perspective view of the battery pack according to the first embodiment.

[0058] Referring to FIGS. 1 and 2, the battery pack according to the present invention includes a battery pack case 100 configured to receive one or more battery modules 200 and a heat sink 300 located above the battery modules 200, wherein each of the battery modules 200 includes a plurality of battery cells 220, a water tank 230 located above the plurality of battery cells 220, and a module case 210 configured to receive the plurality of battery cells 220 and the water tank 230.

[0059] A through-hole is formed in the lower surface of the water tank 230. A sealing member 231 is added to the through-hole in order to prevent discharge of a coolant received in the water tank 230 through the through-hole when the battery cells are in a normal state. Since the sealing member 231 is added to the lower surface of the water tank, the sealing member is not visible from above the water tank 230. For the convenience of description, however, the sealing member 231 is shown in FIG. 2.

[0060] In a concrete example, each of the plurality of battery cells 220 may be a pouch-shaped battery cell, and outer edge sealed surfaces of electrode assembly receiving portions are disposed so as to be perpendicular to the ground in the state in which the pouch-shaped battery cells are stacked such that the electrode assembly receiving portions are in tight contact with each other.

[0061] The pouch-shaped battery cell may be a bidirectional battery cell having a positive electrode lead and a negative electrode lead protruding in opposite directions or a unidirectional battery cell having a positive electrode lead and a negative electrode lead protruding in the same direction.

[0062] The module case 210 may be configured to wrap opposite ends of a battery cell stack, in which the bottoms of the electrode assembly receiving portions are disposed so as to be perpendicular to the ground, parallel to the bottoms of the electrode assembly receiving portions and to wrap the upper surface and the lower surface of the battery cell stack.

[0063] In the module case 210, the water tank 230 is disposed above the battery cell stack. The battery cell stack and the water tank 230 may be disposed so as to be adjacent to each other, or the battery cell stack and the water tank may be disposed so as to be spaced apart from each other.

[0064] The water tank 230 may be mounted integrally to the inside of the upper surface of the module case 210, and the water tank 230 may be the upper surface of the module case 210.

[0065] In another embodiment, the module case 210 may be configured in a U shape in order to wrap the opposite ends of the battery cell stack parallel to the bottoms of the electrode assembly receiving portions and the lower surface of the battery cell stack.

[0066] Alternatively, the module case 210 may be a box open at the upper part thereof configured to wrap the other surfaces of the battery cell stack excluding the upper surface, and the water tank 230 may be coupled to the module case 210 so as to cover the open upper surface of the module case 210.

[0067] That is, the water tank 230 is disposed at the upper surface of the battery cell stack, and therefore the water tank may serve as a cover of the module case 210 having the open upper surface.

[0068] The heat sink 300 is configured to have a size that covers the upper surfaces of all of the battery modules 220 received in the battery pack case 100, and heat exchange between coolants received in all of the water tanks may be performed through the heat sink 300.

[0069] In connection therewith, a flow path 310 configured to guide flow of the coolant is formed in the heat sink 300, and the temperature of the coolant introduced into and discharged from the heat sink 300 may be maintained at a predetermined level.

[0070] The battery pack case 100 may be configured to be open at the upper part thereof, and the heat sink 300 may be coupled to the battery pack case 100 so as to cover the upper surface of the battery pack case 100. Of course, it is obvious that a separate upper cover may be further provided above the heat sink 300.

[0071] The water tank 230 is formed in a rectangular parallelepiped shape in which the lower surface of the water tank that faces the plurality of battery cells and the upper surface of the water tank, which is opposite the lower surface, are wide, and the area of each of the upper surface and the lower surface corresponds to the area of the upper surface of the battery cell stack.

[0072] During repeated charging and discharging of the battery cell 220, the electrode assembly is expanded and contracted, and gas is generated as a byproduct of charging and discharging. As a result, the module case may swell. A partition wall 110 may be added between one module case 210 and another module case 210 in order to minimize the effect of swelling of one module case 210 on module cases adjacent thereto and to fix and support the module cases 210.

[0073] FIG. 3 is a sectional view of the battery pack taken along line A-A′ of FIG. 1, and FIG. 4 is a schematic view illustrating a situation in which flames are extinguished when fire breaks out in the battery pack according to the first embodiment.

[0074] Referring to FIGS. 3 and 4, a plurality of module cases 210 is disposed in the battery pack case 100, and a plurality of battery cells 220 and one water tank 230 are disposed in one module case 210. The heat sink 300 is disposed above the plurality of module cases 210, and a coolant W.sub.2 is circulated in the heat sink 300 while being introduced thereinto and discharged therefrom in order to cool the battery pack.

[0075] A through-hole is formed in one surface of the water tank 230 that faces the plurality of battery cells 220, and a sealing member 231 is added to the through-hole in order to hermetically seal the through-hole. The sealing member 231 is made of a material that is melted by high-temperature gas or sparks discharged from the battery cell 220. That is, when the battery cell 220 is in a normal state, the state in which the through-hole is hermetically sealed by the sealing member 231 is maintained. When the temperature of an ignited battery cell, e.g. a battery cell 220′, exceeds the melting temperature of the sealing member 231, however, the sealing member 231 is melted, whereby the through-hole is opened. Consequently, a coolant W.sub.1 in the water tank 230 may be directly introduced into the battery cell.

[0076] The coolant received in the water tank 230 is evaporated by fire outbreak in the battery cell, whereby the volume of the coolant is increased and thus the coolant is transformed into a high pressure state. When the through-hole 232 is opened, therefore, the coolant may be sprayed toward the ignited battery cell at a high pressure.

[0077] At this time, the shape of the sealing member 231 that is not adjacent to the ignited battery cell 220′ may be maintained without melting. Consequently, the coolant may be ejected through only the through-hole from which the sealing member has been removed.

[0078] The sealing member may be made of a thermoplastic polymer resin having a melting point of about 200° C. or less. For example, a material having a melting point of about 100° C. to about 200° C., such as polyethylene or polypropylene, may be used as the thermoplastic polymer resin.

[0079] The through-hole 232 is filled with the sealing member 231, and the sealing member may include an extension portion 235 further extending outwards from the outer surface of the water tank than the circumference of the through-hole. The extension portion 235 is a portion that further extends from the outer surface of the water tank. In a normal state, the extension portion may increase the force of coupling between the water tank and the sealing member 231. When fire breaks out in the battery cell, the extension portion may be rapidly melted to open the through-hole.

[0080] Meanwhile, in consideration of the fact that the coolant W.sub.1 is directly injected into the pouch-shaped battery cell, it is necessary to prevent flames of the pouch-shaped battery cell from expanding or to prevent explosion of the pouch-shaped battery cell due to injection of the coolant. Consequently, it is preferable for no combustible material to be used as an additive included in the coolant. Alternatively, in the case in which a combustible material is used as the additive, the additive may be added in an amount sufficient to prevent secondary explosion of the pouch-shaped battery cell and in such an amount that the additive is used as an antifreeze solution in order to prevent freezing of the coolant.

[0081] The coolant W.sub.2 introduced into and discharged from the heat sink may be the same liquid as the coolant W.sub.1 received in the water tank. For example, water may be used as the coolant W.sub.1 and/or the coolant W.sub.2.

[0082] When a battery cell constituted by a lithium secondary battery is defective, overcharged, or overheated, a thermal runaway phenomenon occurs in the battery cell. When the battery cell is in a thermal runaway state, the temperature of the battery cell may rise up to a temperature at which gas venting occurs, e.g. about 260° C. In addition, the temperature of the battery cell may be continuously increased while gas venting occurs.

[0083] In the case in which a plurality of battery cells is received in a battery pack case to manufacture a battery pack, when one battery cell is in a thermal runaway state, heat and flames may be transferred to a battery cell adjacent thereto, whereby the adjacent battery cell may be overheated and may thus be in a thermal runaway state. The battery cell in the thermal runaway state may heat another battery cell adjacent thereto, whereby a thermal runaway chain reaction may occur. When a battery cell in a thermal runaway state is present in the battery pack case, therefore, thermal runaway of a plurality of battery cells may occur, and this may spread more widely, whereby great damage may be caused. In the case in which a plurality of battery cells is in a thermal runaway state, the battery cells may reach a temperature of about 1000° C. or higher, and this temperature is maintained until the battery cells are completely destroyed by fire, whereby a user may be in danger.

[0084] Consequently, it is very important to extinguish the ignited battery cell before flames and heat of the ignited battery cell spread to a battery cell adjacent thereto.

[0085] In the battery pack according to the present invention, therefore, the water tank 230 containing the coolant W.sub.1 is provided at a position adjacent to the upper parts of the plurality of battery cells 220, and the through-hole, through which the coolant W.sub.1 flows out, is hermetically sealed by the sealing member having a low melting point. When fire breaks out in the battery cell 220′, therefore, the sealing member 231 adjacent thereto is melted to open the through-hole 232. Consequently, the coolant received in the water tank 230 is directly introduced into the battery cell 220′ through the through-hole. The overheated or ignited pouch-shaped battery cell is rapidly extinguished or cooled through the above process, whereby it is possible to rapidly prevent spread of thermal runaway, and therefore it is possible to secure time necessary to extinguish flames of the battery cell using a watering facility located at the outside.

[0086] In addition, even though the battery pack according to the present invention is mounted at a position close to a user, e.g. in an electric vehicle, it is possible to rapidly extinguish flames of the battery cell, and therefore it is possible to secure user safety.

[0087] The through-hole 232 formed in the water tank 230 may be configured to have a structure in which a plurality of holes is formed in one surface of the water tank so as to be uniformly dispersed. Even though fire breaks out in a certain battery cell, therefore, a sealing member located so as to be adjacent thereto may be melted. Even though fire breaks out in a battery cell located at a certain position, therefore, the coolant may be directly injected into the ignited battery cell irrespective of the position of the battery cell. That is, the number of through-holes formed in the water tank may be set in consideration of the size and number of battery module housings and the shape, size, and number of battery cells disposed in the battery module housing.

[0088] FIG. 5 is an exploded perspective view of a battery pack according to a second embodiment, FIG. 6 is a sectional view of the battery pack according to the second embodiment, and FIG. 7 is a schematic view illustrating a situation in which flames are extinguished when fire breaks out in the battery pack according to the second embodiment.

[0089] Referring to FIGS. 5 to 7, the battery pack includes a battery pack case 100 configured to receive one or more battery modules 200 and a heat sink 300 located above the battery modules 200, wherein each of the battery modules 200 includes a plurality of battery cells 220, a water tank 230 located above the plurality of battery cells 220, and a module case 210 configured to receive the plurality of battery cells 220 and the water tank 230.

[0090] Each of the plurality of battery cells 220 is a prismatic battery cell that is generally configured to have a hexahedral structure and that has an electrode assembly received in a battery case made of a metal material, wherein a positive electrode terminal and a negative electrode terminal may protrude from the upper surface of the prismatic battery cell so as to face the water tank 230. The prismatic battery cells may be disposed in tight contact with each other such that relatively wide side surfaces of the prismatic battery cells are stacked so as to be adjacent to each other.

[0091] In addition, a through-hole is formed in one surface of the water tank 230 that faces the plurality of battery cells, and a sealing member 231 made of a material that has a low melting point is added to the through-hole. When fire breaks out in the battery cell, the sealing member may be melted to open the through-hole, and the coolant received in the water tank may be directly introduced into the battery cell 220 through the through-hole.

[0092] In addition thereto, the description of the battery pack according to the first embodiment is equally applicable to the battery pack according to the second embodiment. In addition, the same components of the second embodiment as the first embodiment may be denoted by the same reference numerals.

[0093] FIG. 8 is an exploded perspective view of a battery pack according to a third embodiment, FIG. 9 is a sectional view of the battery pack according to the third embodiment, and FIG. 10 is a schematic view illustrating a situation in which flames are extinguished when fire breaks out in the battery pack according to the third embodiment.

[0094] Referring to FIGS. 8 to 10, the battery pack includes a battery pack case 100 configured to receive one or more battery modules 200 and a heat sink 300 located above the battery modules 200, wherein each of the battery modules 200 includes a plurality of battery cells 220, a water tank 230 located above the plurality of battery cells 220, and a module case 210 configured to receive the plurality of battery cells 220 and the water tank 230. Each of the plurality of battery cells 200 is a cylindrical battery cell that is generally configured to have a cylindrical structure and that has an electrode assembly received in a battery case made of a metal material, wherein a positive electrode terminal may protrude upwards so as to face the water tank 230.

[0095] In addition, a through-hole is formed in one surface of the water tank 230 that faces the plurality of battery cells, and a sealing member 231 made of a material that has a low melting point is added to the through-hole. When fire breaks out in the battery cell, the sealing member may be melted to open the through-hole, and the coolant received in the water tank may be directly introduced into the battery cell 220 through the through-hole.

[0096] In addition thereto, the description of the battery pack according to the first embodiment is equally applicable to the battery pack according to the third embodiment. In addition, the same components of the third embodiment as the first embodiment may be denoted by the same reference numerals.

[0097] Those skilled in the art to which the present invention pertains will appreciate that various applications and modifications are possible within the category of the present invention based on the above description.

DESCRIPTION OF REFERENCE SYMBOLS

[0098] 100: Battery pack case [0099] 110: Partition wall [0100] 200: Battery module [0101] 210: Module case [0102] 220, 220′: Battery cells [0103] 230: Water tank [0104] 231: Sealing member [0105] 232: Through-hole [0106] 235: Extension portion [0107] 300: Heat sink [0108] 310: Flow path [0109] W.sub.1, W.sub.2: Coolants