Battery pack with a double top cover with vent gas discharge passages

Abstract

The battery module according to the present invention includes a pack tray configured to accommodate at least one battery module therein, a pack cover configured to cover an upper portion of the pack tray and having a vent gas discharge passage formed therein, and a top plate portion configured between the pack tray and the pack cover, with a lower portion facing the battery module and an upper portion communicating with the discharge passage, and configured to selectively discharge only the vent gas among flames, high-temperature particles, and vent gas generated in the battery module.

Description

[Technical Field]

[0001] This application claims priority based on Korean Patent Application No. 10-2022-0102972, filed on August 17, 2022, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings thereof.

[0002] The present invention relates to a battery pack, and more specifically, to a battery pack that easily vents gas generated in the event of an internal fire in a battery module to the outside while preventing flames and high-temperature particles from escaping to the outside, thereby preventing or delaying as much as possible chain fires of fires in other adjacent battery modules. [Background technology]

[0003] Semi-permanent batteries that convert electrical energy into chemical energy and can be repeatedly charged and discharged are called secondary batteries, in distinction from primary batteries, which cannot be reused once used.

[0004] Secondary batteries include lithium secondary batteries, nickel-cadmium (Ni-Cd) batteries, lead-acid batteries, nickel-metal hydride (Ni-MH) batteries, zinc-air batteries, alkaline manganese batteries, etc. Of these, lead-acid batteries and lithium secondary batteries are the most commercially available secondary batteries.

[0005] In particular, lithium secondary batteries have recently been actively used as electric vehicle batteries due to their advantages of high energy storage density, lightweight and compact size, excellent safety, low discharge rate, and long life. For reference, lithium secondary batteries are generally classified into cylindrical, prismatic, and pouch types depending on their manufacturing form, and their uses range from electric vehicle batteries to ESS batteries and other electrical devices.

[0006] Currently, the operating voltage of one lithium secondary battery cell is approximately 2.5 V to 4.5 V. Therefore, in order to use secondary batteries as an energy source for electric vehicles, a battery module is formed by connecting multiple lithium ion battery cells in series and / or in parallel, and a battery pack is formed by connecting the battery modules in series and / or in parallel.

[0007] However, because secondary batteries undergo chemical reactions during charging and discharging, their performance may deteriorate if they are used in environments higher than the appropriate temperature. Furthermore, if heat is not controlled to an appropriate temperature, there is always the risk of unexpected fire or explosion. Furthermore, because battery modules are constructed with such secondary batteries concentrated within a module housing, if any secondary battery experiences thermal runaway and becomes a trigger cell, a large amount of vent gas is generated from the lithium secondary battery. As degradation progresses, flames and high-temperature particles containing electrode active material and aluminum particles are generated, and these flames and high-temperature particles may be ejected outside the battery module along with the vent gas. The emitted flames and high-temperature sparks can cause thermal damage to the ignited battery module and other adjacent battery modules, accelerating the ignition of other battery modules.

[0008] Therefore, there is an urgent need to improve the structure of the battery pack so that flames and high-temperature sparks from the first ignited battery module are not easily discharged to the outside of the battery module, while vent gas can be easily discharged. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a battery pack that can prevent or delay as much as possible chain fire of other adjacent battery modules by preventing flames and high-temperature particles from easily escaping to the outside when an internal fire occurs in a battery module, while allowing vent gas to be easily discharged to the outside through an exhaust passage.

[0010] 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]

[0011] The battery pack according to the present invention may include a pack tray configured to accommodate at least one battery module therein; a pack cover configured to cover an upper portion of the pack tray and having a vent gas discharge passage formed therein; and a top plate unit configured between the pack tray and the pack cover, with a lower portion facing the battery module and an upper portion communicating with the discharge passage, and configured to selectively discharge only the vent gas from among flames, high-temperature particles, and vent gas generated in the battery module.

[0012] The top plate portion may include a support frame forming a frame-like skeleton, an upper plate and a lower plate whose edges are supported by the support frame, have vent holes through which the vent gas is discharged, and are arranged to overlap each other, and a flame-blocking mesh layer provided between the upper plate and the lower plate to block the discharge of the flame and high-temperature particles.

[0013] The top plate portion may further include a flame-retardant pad layer disposed under the lower plate, and the flame-retardant pad layer may have a discharge slit in an area corresponding to the vent hole of the lower plate, the discharge slit being configured to tear when pressure exceeding an allowable pressure is applied.

[0014] The fire-blocking mesh layer may be provided in a mesh structure.

[0015] The pack tray may be provided with an internal partition wall that separates and arranges the battery modules, and the top plate portion may be fixedly coupled to the pack tray and the internal partition wall.

[0016] The top plate portion may be coupled to the pack tray and the internal partition wall with fixing screws, and a seal member may be provided between the top plate portion and the pack tray.

[0017] The flame-retardant pad layer may have an inlet section on the battery module side, and the inlet section may be tapered inward in a thickness direction to guide the vent gas in.

[0018] The flame-retardant pad layer may have an outlet section on the lower plate side, and the outlet section may be tapered to expand to the inner diameter of the vent hole.

[0019] The discharge slit may be formed by making an H-shaped or I-shaped cut along a dotted line.

[0020] The discharge slits may be in the form of a plurality of gradually increasing ovals.

[0021] According to another aspect of the present invention, a vehicle including the battery pack can be provided. [Effects of the Invention]

[0022] According to one aspect of the present invention, when a battery module ignites internally, flames and high-temperature particles are prevented from easily escaping to the outside, while vent gas is easily discharged to the outside through an exhaust passage, thereby preventing or delaying as much as possible chain fires of other adjacent battery modules.

[0023] Even if a battery module catches fire and releases vent gas and sparks, the thermal damage to other battery modules is minimized, thereby increasing the durability of the battery pack and reducing maintenance costs.

[0024] The effects of the present invention are not limited to those mentioned above, and effects not mentioned will be clearly understood by a person having ordinary skill in the art to which the present invention pertains from this specification and the accompanying drawings.

[0025] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concepts of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic perspective view of a battery pack according to an embodiment of the present invention; [Figure 2] FIG. 2 is an exploded perspective view of the main components of the battery pack of FIG. 1. [Figure 3] FIG. 3 is a schematic perspective view of the top plate portion of FIG. 2. [Figure 4] FIG. 2 is a partially cutaway perspective view of a top plate portion according to an embodiment of the present invention. [Figure 5] FIG. 2 is a schematic bottom view of a top plate portion according to an embodiment of the present invention. [Figure 6] 2 is a schematic vertical cross-sectional view of a battery pack according to an embodiment of the present invention, taken along an X-axis direction. FIG. [Figure 7] 10 is a diagram illustrating a path along which vent gas is discharged through a passage in a battery pack according to an embodiment of the present invention. FIG. [Figure 8] 3A and 3B are schematic cross-sectional and bottom views of a flame-retardant padding layer according to another embodiment of the present invention. [Figure 9]10 is a schematic longitudinal sectional view of a battery pack including a top plate part to which a flame-retardant pad layer is applied according to another embodiment of the present invention. [Figure 10] 10A and 10B are diagrams showing other shapes of discharge slits according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and claims should not be construed as being limited to their ordinary and dictionary meanings, but should be construed as meanings and concepts corresponding to the technical ideas of the present invention, based on the principle that the inventors themselves can appropriately define the concepts of terms in order to best describe the invention. Therefore, it should be understood that the configurations shown in the embodiments described in this specification are merely the most preferred embodiment of the present invention and do not represent the entire technical ideas of the present invention, and therefore various equivalents and modifications that can be substituted therefor may exist at the time of filing this application.

[0028] FIG. 1 is a schematic perspective view of a battery pack according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the main components of the battery pack of FIG.

[0029] The battery pack 1 according to the present embodiment may include a pack tray 100 configured to accommodate at least one battery module 10 therein; a pack cover 200 configured to cover the upper portion of the pack tray 100 and having a vent gas discharge passage formed therein; and a top plate unit 300 configured between the pack tray 100 and the pack cover 200, with a lower portion facing the battery module 10 and an upper portion connected to the discharge passage, and configured to selectively discharge only the vent gas among flames, high-temperature particles, and vent gas generated in the battery module 10.

[0030] The pack tray 100 is a component for protecting the battery module 10 from external impacts, etc., and is made of a material with excellent mechanical rigidity. As shown in Figures 1 and 2, the pack tray 100 is configured to accommodate at least one battery module 10 inside.

[0031] A plurality of internal partitions 110 are provided inside the pack tray 100 to compartmentalize and arrange the battery modules 10. In this embodiment, four battery modules 10 are accommodated inside the pack tray 100, but the scope of the present invention is not limited to the number of battery modules 10 or the number of internal partitions 110 of this embodiment.

[0032] The pack cover 200 is disposed to cover the top of the pack tray 100, and is a portion in which a vent gas discharge passage 210 is formed. The discharge passage 210 can be regarded as a type of discharge space or a retention or storage space, and although not shown, a partition, slit, baffle member, or the like that guides and directs a plurality of discharge paths may be provided. In addition, when the pack tray 100 and the pack cover 200 are coupled to each other, for example, a coupling method such as bolting, welding, adhesive, or hooking may be applied.

[0033] The battery module 10 is surrounded by a module case 12 (see FIG. 6) and housed inside a pack tray 100. The upper surface of the module case 12 is provided with a plurality of openings 11 on both sides, through which vent gas is discharged in the event of an internal fire in the battery module 10.

[0034] Meanwhile, there is an urgent need to improve the structure of the battery pack so that flames and high-temperature sparks from the first ignited battery module 10 are not easily discharged to the outside of the battery module 10, while vent gas is easily discharged. Therefore, this embodiment discloses a double-structure top cover method in which a top plate part 300 is placed between the pack tray 100 and the pack cover 200, and a discharge passage is provided at the top end of the battery module 10.

[0035] 3 is a schematic perspective view of the top plate portion of FIG. 2, FIG. 4 is a partially cutaway perspective view of the top plate portion according to one embodiment of the present invention, FIG. 5 is a schematic bottom view of the top plate portion according to one embodiment of the present invention, and FIG. 6 is a schematic longitudinal cross-sectional view in the X-axis direction of a battery pack according to one embodiment of the present invention.

[0036] The top plate part 300 is provided between the pack tray 100 and the pack cover 200, and has a lower part in surface contact with the battery module 10 and an upper part connected to the exhaust passage 210, so that it can selectively exhaust only the vent gas among the flames, high-temperature particles, and vent gas generated in the battery module 10.

[0037] To this end, the top plate part 300 may include a support frame 301 forming a frame-like skeleton, an upper plate 310 and a lower plate 320 whose edges are supported by the support frame 301 and have vent holes 311 and 321 through which the vent gas is discharged, and which are arranged to overlap each other, a flame-blocking mesh layer 330 provided between the upper plate 310 and the lower plate 320 to block the discharge of the flame and high-temperature particles, and a flame-retardant pad layer 340 arranged under the lower plate 320.

[0038] The support frame 301 is a part that forms the framework of the top plate part 300. The support frame 301 is configured to accommodate the upper plate and the lower plate, and is seated and supported on the upper surfaces of the pack tray 100 and the internal partition wall 110. The support frame 301 is provided with a plurality of screw fastening holes 302, and is screw-coupled around the battery module 10 in the upper region of the battery module 10 using fixing screws 350. Meanwhile, the support frame 301 in this embodiment may be made of a material with excellent mechanical rigidity.

[0039] The upper plate 310 is provided to correspond to the size of the battery module 10 and to cover the opening on the upper surface of the battery module 10. The upper plate 310 is provided to be accommodated in the support frame 301, and when accommodated, the plate surface of the upper plate 310 may be provided without any step relative to the height of the plate surface of the support frame 301, or the height of the plate surface of the upper plate 310 may be configured to protrude or recess relatively for convenience in processing and assembly. Meanwhile, the upper plate 310 in this embodiment is made of a stainless steel material, which has advantages of excellent heat absorption rate and thermal conductivity, and excellent durability against high-temperature vent gas and sparks.

[0040] The lower plate 320 has substantially the same size and shape as the upper plate 310, and is also made of SUS material.

[0041] A plurality of vent holes 311, 321 are formed on the plate surfaces of the upper plate 310 and the lower plate 320 at positions corresponding to the above-mentioned opening holes 11 of the battery module 10. Vent gas can be ejected through the vent holes 311, 321.

[0042] 4 and 6, the fire-blocking mesh layer 330 is interposed between the upper plate 310 and the lower plate 320. That is, the fire-blocking mesh layer 330 is disposed between the upper plate 310 and the lower plate 320 to block the vent holes 311 and 321. The fire-blocking mesh layer 330 may have a mesh structure and be made of a metal material that does not easily melt due to heat. As a result, when flames, high-temperature particles, and vent gases generated in the battery module 10 are discharged through the open hole 11 and ejected through the vent holes 311 and 321, the flames, high-temperature particles, etc. are blocked by the fire-blocking mesh layer 330, preventing them from ejecting to the outside, and only the vent gases are selectively ejected.

[0043] As a result, even if flames, sparks, high-temperature particles, etc. are generated in a catching fire battery module 10, these can be isolated within the battery module 10 and prevented from leaking to the outside, thereby minimizing thermal damage to other battery modules 10. In addition, vent gas, which requires volumetric risk management, can be easily discharged to the outside of the battery module 10, thereby preventing or delaying thermal runaway of the battery pack.

[0044] The flame-retardant pad layer 340 is provided on the lower plate 320, but is provided facing the lower plate 320 and is disposed in close contact with the battery module 10. Here, the flame-retardant pad layer 340 may be made of a material with low thermal conductivity and excellent heat resistance (e.g., silicone or mica). If an internal fire occurs in the battery module 10 with the flame-retardant pad layer 340 interposed, heat, high-temperature particles, flames, etc. generated in the ignited battery module 10 move to the upper side of the battery module 10, minimizing their propagation to adjacent battery cells 111.

[0045] The flame-retardant pad layer 340 has exhaust slits 341 formed in a region corresponding to the vent holes 321 of the lower plate 320, configured to tear when pressure exceeding an allowable pressure is applied. The exhaust slits 341 are formed by making an H-shaped or I-shaped cut along a dotted line. For example, when a pressure exceeding the designed allowable pressure is applied in a ignited battery module 10, the exhaust slits 341 tear to discharge vent gas.

[0046] Alternatively, the exhaust slits 341B may have a plurality of gradually increasing oval shapes, as shown in FIG. 10. In this case, the size of the exhaust slits 341B that are cut may vary depending on the pressure difference above the designed allowable pressure, and the actual exhaust area for vent gas may change. For example, when the pressure is within a preset pressure range, the smallest oval exhaust slits 341B are cut off to discharge vent gas, and when the pressure exceeds the preset pressure range, the intermediate or largest oval exhaust slits 341B are cut off to discharge a relatively large amount of vent gas.

[0047] The top plate unit 300 may be coupled to the pack tray 100 and the internal partition wall 110 with fixing screws 350. In addition, a seal member 360 is installed between the top plate unit 300 and the pack tray 100, so that the space between one battery module 10 and another adjacent battery module 10 can be completely isolated.

[0048] According to this embodiment, when an internal fire occurs in the battery module 10, flames and high-temperature particles are prevented from easily escaping to the outside, while vent gas can be easily discharged to the outside.

[0049] Furthermore, according to this embodiment, even if vent gas and sparks are generated in the ignited battery module 10, thermal damage to other battery modules 10 can be minimized, thereby preventing or delaying thermal runaway of the battery pack.

[0050] FIG. 7 is a diagram showing a path along which vent gas is discharged in a battery pack according to one embodiment of the present invention.

[0051] Hereinafter, a process for easily discharging vent gas to the outside according to the present embodiment will be described in detail with reference to FIGS.

[0052] First, when an internal fire occurs in a specific battery module 10 as shown in FIG. 7, the pressure inside the module case 12 of the battery module 10 increases, and as a result, the pressure below the flame-retardant pad layer 340 increases due to the vent gas discharged along the open hole 11.

[0053] Then, when the pressure rises above the design pressure, the exhaust slit 341 in the flame-retardant pad layer 340 adjacent to the battery module 10 is torn and cut, causing flames containing vent gas and high-temperature particles to be ejected upward.

[0054] Next, the mesh structure of the flame-blocking mesh layer 330 provided on the vent holes 311, 321 of the upper plate 310 and the lower plate 320 allows vent gas to pass smoothly while preventing the discharge of flames and particles. This prevents flames and high-temperature particles from easily escaping to the outside while allowing vent gas to easily be discharged to the outside, thereby minimizing thermal damage to other battery modules 10 and preventing or delaying thermal runaway of the battery pack.

[0055] The vent gas then passes through the vent holes 311 in the upper plate 310 to be temporarily stored or flow into the exhaust passage 210, and can be safely exhausted to the outside via an additional exhaust line (not shown in the drawing). During this process, the vent gas may flow into an adjacent battery module 10, but as shown in FIG. 7, the exhaust slits 341 in the flame-retardant pad layer on the top of the adjacent battery module 10 are still blocked, so the inflow of the vent gas into other battery modules 10 can be fundamentally blocked, thereby minimizing thermal damage to the other battery modules 10.

[0056] Furthermore, by taking the volume of vent gas into consideration and securing the exhaust passage 210, there is an advantage in that thermal damage to all other battery modules 10 inside the battery pack can be delayed, and evacuation time can be gained before thermal runaway occurs.

[0057] Next, another embodiment of the battery module 10 of the present invention will be briefly described with reference to FIGS.

[0058] FIG. 8 is a schematic cross-sectional view and bottom view of a flame-retardant pad layer according to another embodiment of the present invention, and FIG. 9 is a schematic vertical cross-sectional view of a battery pack including a top plate portion to which a flame-retardant pad layer according to another embodiment of the present invention is applied.

[0059] The same reference numerals as in the above-described drawings indicate the same components, and redundant explanations of the same components will be omitted, with the explanation focusing on differences from the above-described embodiment.

[0060] Compared to the above-described embodiment, the battery module 10 according to another embodiment of the present invention has an additional configuration in the flame-retardant pad layer 340. The flame-retardant pad layer 340 may have an inlet section 342 provided on the battery module 10 side and tapered inward in the thickness direction to guide the intake of the vent gas, and an outlet section 343 provided on the lower plate 320 side and tapered to the inner diameter of the vent hole 311.

[0061] 8, the inlet section 342 is tapered inward in the thickness direction, thereby allowing vent gas generated in the battery module 10 to be easily drawn into the vent hole 321. The outlet section 343 is provided on the lower plate 320 side and is tapered to expand to the inner diameter of the vent hole 311, allowing the gas to be easily discharged through the vent hole 311 and the discharge passage 210.

[0062] As a result, the vent gas can be easily discharged to the outside through the discharge passage 210, minimizing thermal damage to other battery modules 10, thereby preventing or delaying thermal runaway of the battery pack.

[0063] In addition, compared to the first embodiment, the thickness and size of the exhaust slit 341A of the flame-retardant pad layer 340 in the second embodiment are relatively reduced, which allows the range of cutting pressure to be finely adjusted, enabling fine control in terms of gas exhaust control according to the amount of vent gas exhausted.

[0064] Meanwhile, the battery pack 1 according to the present invention may further include various devices for controlling the charging and discharging of the battery module 10, such as a BMS (Battery Management System), a current sensor, a fuse, etc., although not shown.

[0065] The battery pack 1 according to the present invention can be applied to automobiles such as electric vehicles and hybrid vehicles. That is, the automobile according to the present invention can include the battery pack 1 according to the present invention. The battery pack 1 is installed in the body frame under the seat of the vehicle or in the trunk space, and when installing the battery pack in the vehicle, the installation procedure of the battery pack can be reversed as needed.

[0066] Although terms indicating directions such as up, down, left, right, front, and rear are used in this specification, it will be obvious to those skilled in the art that these terms are used for the convenience of explanation and may vary depending on the position of the object of interest, the position of the observer, etc.

[0067] As described above, the present invention has been described using limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that a person having ordinary knowledge in the technical field to which the present invention pertains can make various modifications and variations within the technical spirit of the present invention and the equivalent scope of the following claims. [Explanation of symbols]

[0068] 1 battery pack 10 Battery Module 11 Open hole 12 Module Case 100 pack tray 110 Internal bulkhead 111 Battery Cells 200 pack covers 210 Discharge passage 300 Top plate section 301 Support Frame 302 Fastening hole 310 Upper Plate 311 Vent hole 320 Lower Plate 321 Vent hole 330 Fire-blocking mesh layer 340 Flame-retardant padding layer 341 Discharge slit 342 Entrance section 343 Exit Section 360 Sealing material

Claims

1. a pack tray configured to accommodate at least one battery module therein; a pack cover provided to cover an upper portion of the pack tray and having a discharge passage for vent gas formed therein; a top plate unit provided between the pack tray and the pack cover, the top plate unit having a lower portion facing the battery module and an upper portion communicating with the exhaust passage, and configured to selectively exhaust only the vent gas among flames, high-temperature particles, and vent gas generated in the battery module; A battery pack comprising: The top plate portion is a support frame forming a frame-like skeleton; an upper plate and a lower plate, each edge of which is supported by the support frame and has a vent hole through which the vent gas is discharged, which are disposed on top of each other; a flame-blocking mesh layer provided between the upper plate and the lower plate to block the discharge of the flame and high-temperature particles; Including the battery pack.

2. The top plate portion further includes a flame-retardant pad layer disposed under the lower plate, 2. The battery pack according to claim 1, wherein the flame-retardant pad layer has a discharge slit in a region corresponding to the vent hole of the lower plate, the discharge slit being configured to tear when pressure greater than an allowable pressure is applied.

3. The battery pack according to claim 1 , wherein the flame-blocking mesh layer has a mesh structure.

4. A pack tray configured to accommodate at least one battery module therein; a pack cover provided to cover an upper portion of the pack tray and having a discharge passage for vent gas formed therein; a top plate unit provided between the pack tray and the pack cover, the top plate unit having a lower portion facing the battery module and an upper portion communicating with the exhaust passage, and configured to selectively exhaust only the vent gas among flames, high-temperature particles, and vent gas generated in the battery module; A battery pack comprising: the pack tray is provided with an internal partition wall to compartmentalize and arrange the battery modules; The top plate portion is fixedly coupled to the pack tray and the internal partition wall.

5. the top plate portion is connected to the pack tray and the internal partition wall with fixing screws; The battery pack according to claim 4 , wherein a seal member is provided between the top plate portion and the pack tray.

6. 3. The battery pack according to claim 2, wherein the flame-retardant pad layer has an inlet section on the battery module side, the inlet section being tapered inward in a thickness direction to guide the vent gas.

7. The battery pack according to claim 2 , wherein the flame-retardant pad layer has an outlet section on the lower plate side, the outlet section tapering to an inner diameter of the vent hole.

8. The battery pack according to claim 2 , wherein the discharge slit is formed by making an H-shaped or I-shaped cut along a dotted line.

9. The battery pack according to claim 2 , wherein the discharge slits are in the shape of a plurality of gradually increasing ellipses.

10. A motor vehicle comprising a battery pack according to any one of claims 1 to 9.

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