Battery pack having double top cover with venting gas passage

Abstract

A battery pack according to the present invention may include: a pack tray provided to accommodate at least one battery module inside; a pack cover provided to cover the upper part of the pack tray and having a venting gas discharge passage formed inside; and a top plate portion provided between the pack tray and the pack cover, wherein the lower part faces the battery module and the upper part communicates with the discharge passage, and is configured to selectively discharge only the venting gas among the flame, high-temperature particles, and venting gas generated from the battery module.

Description

Technology Field

[0001] The present invention relates to a battery pack, and more specifically, to a battery pack that allows gas generated during internal ignition of a battery module to be easily vented to the outside, while preventing flames or high-temperature particles from leaking out to the outside, thereby preventing or delaying as much as possible the chain ignition of adjacent battery modules. Background Technology

[0002] Semi-permanent batteries that convert electrical energy into the form of chemical energy and can be repeatedly charged and discharged are referred to as secondary batteries to distinguish them from primary batteries, which cannot be reused after a single use.

[0003] Rechargeable batteries include lithium-ion batteries, nickel-cadmium (Ni-Cd) batteries, lead-acid batteries, nickel-hydrogen (Ni-MH) batteries, air-zinc batteries, and alkaline manganese batteries. Among these, lead-acid batteries and lithium-ion batteries are considered the most actively commercialized rechargeable batteries.

[0004] In particular, lithium-ion batteries are actively being utilized as electric vehicle batteries recently due to their high energy storage density, the ability to be lightweight and miniaturized, excellent safety, low discharge rate, and long lifespan. For reference, lithium-ion batteries are generally classified into cylindrical, prismatic, and pouch types depending on their manufacturing form, and their applications extend beyond electric vehicle batteries to include ESS batteries and other electrical devices.

[0005] Currently, the operating voltage of a single lithium secondary battery cell is approximately 2.5V to 4.5V. Therefore, in order to apply secondary batteries as an energy source for electric vehicles, a battery module is configured by connecting multiple lithium-ion battery cells in series and / or parallel, and a battery pack is configured by connecting the battery modules in series and / or parallel.

[0006] Meanwhile, since secondary batteries involve chemical reactions during charging and discharging, their performance may degrade if used in environments higher than the optimal temperature. Furthermore, if thermal control is not maintained at the appropriate temperature, there is a constant risk of unexpected ignition or explosion. Additionally, battery modules are structured to intensively house these secondary batteries within a module housing; therefore, if even a single secondary battery undergoes heat runaway and becomes a trigger cell, a large amount of venting gas may be generated from the lithium secondary batteries. If degradation intensifies, high-temperature particles, including electrode active materials and aluminum particles, may be produced along with flames. These flames and high-temperature particles, along with the venting gas, can be ejected to the outside of the battery module. The ejected flames and high-temperature sparks inflict thermal damage on the ignited battery module and adjacent modules, thereby accelerating the ignition of other battery modules.

[0007] Accordingly, there is an urgent need to improve the structure of the battery pack so that flames and high-temperature sparks from the initially ignited battery module are not easily released to the outside, while allowing venting gases to be easily released. The problem to be solved

[0008] The present invention was devised in consideration of the above-mentioned problems and aims to provide a battery pack capable of preventing or maximally delaying chain ignition of adjacent battery modules by ensuring that flames or high-temperature particles do not easily leak to the outside in the event of internal ignition of a battery module, while allowing venting gas to be easily discharged to the outside through a discharge passage.

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

[0010] A battery pack according to the present invention may include: a pack tray provided to accommodate at least one battery module inside; a pack cover provided to cover the upper part of the pack tray and having a venting gas discharge passage formed inside; and a top plate portion provided between the pack tray and the pack cover, wherein the lower part faces the battery module and the upper part communicates with the discharge passage, and is configured to selectively discharge only the venting gas among the flame, high-temperature particles, and venting gas generated from the battery module.

[0011] The top plate portion may include: a support frame forming a frame-like structure; an upper plate and a lower plate each having a rim supported by the support frame and having a venting hole through which the venting gas is discharged, and 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 or high-temperature particles.

[0012] The top plate portion further includes a flame-retardant pad layer disposed below the lower plate, and the flame-retardant pad layer may have a discharge slit configured to tear when a pressure exceeding the allowable pressure is applied in an area corresponding to the venting hole of the lower plate.

[0013] The above flame blocking mesh layer can be provided with a mesh structure.

[0014] The above pack tray is provided with an internal partition for partitioning the battery module, and the top plate portion can be fixedly coupled to the pack tray and the internal partition.

[0015] The top plate portion is connected to the pack tray and the inner partition wall with fixing screws, and a sealing member may be provided between the top plate portion and the pack tray.

[0016] The flame-retardant pad layer may be provided with an inlet section that is tapered inward in the thickness direction to induce the inflow of the venting gas, and is provided on the battery module side.

[0017] The flame-retardant pad layer may be provided with an outlet section that is tapered and expanded to the inner diameter of the venting hole, provided on the lower plate side.

[0018] The above discharge slit may be provided in a form in which a sheath is formed with dotted lines in an H-shape or an I-shape.

[0019] The above discharge slit may be composed of a plurality of elliptical shapes that gradually increase in size.

[0020] According to another aspect of the present invention, a vehicle comprising the battery pack may be provided. Effects of the invention

[0021] According to one aspect of the present invention, when a battery module ignites internally, flames or high-temperature particles are not easily leaked to the outside, while venting gas is easily discharged to the outside through a discharge passage, thereby preventing or maximally delaying chain ignition of adjacent battery modules.

[0022] Even if venting gas and sparks are generated from an ignited battery module, thermal damage to other battery modules can be minimized, thereby increasing the durability of the battery pack and reducing maintenance costs.

[0023] The effects of the present invention are not limited to the effects described above, and unmentioned effects will be clearly understood by those skilled in the art from this specification and the attached drawings. Brief explanation of the drawing

[0024] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is a schematic perspective view of a battery pack according to one embodiment of the present invention. FIG. 2 is an exploded perspective view of the main components of the battery pack of FIG. 1. Figure 3 is a schematic perspective view of the top plate portion of Figure 2. FIG. 4 is a partially cutaway perspective view of a top plate portion according to one embodiment of the present invention. FIG. 5 is a schematic bottom view of a top plate portion according to one embodiment of the present invention. FIG. 6 is a schematic cross-sectional view in the X-axis direction of a battery pack according to one embodiment of the present invention. FIG. 7 is a diagram illustrating the path through which venting gas is discharged via a passage in a battery pack according to one embodiment of the present invention. 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. FIG. 9 is a schematic cross-sectional view of a battery pack including a top plate portion to which a flame-retardant pad layer is applied according to another embodiment of the present invention. FIG. 10 is a drawing illustrating a different shape of an exhaust slit according to another embodiment of the present invention. Specific details for implementing the invention

[0025] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention; therefore, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.

[0026] FIG. 1 is a schematic perspective view of a battery pack according to one embodiment of the present invention, and FIG. 2 is an exploded perspective view of the main components of the battery pack of FIG. 1.

[0027] A battery pack (1) according to the present embodiment may include: a pack tray (100) provided to accommodate at least one battery module (10) inside; a pack cover (200) provided to cover the upper part of the pack tray (100) and having a venting gas discharge passage formed inside; and a top plate portion (300) provided between the pack tray (100) and the pack cover (200), the lower part of which faces the battery module (10) and the upper part of which communicates with the discharge passage, and which selectively discharges only the venting gas among the flame, high-temperature particles, and venting gas generated from the battery module (10).

[0028] The pack tray (100) is a component for protecting battery modules (10) from external shocks, etc., and can be made of a material with excellent mechanical strength, and is provided to accommodate at least one battery module (10) inside, as shown in FIGS. 1 and 2.

[0029] A plurality of internal partitions (110) are provided inside the pack tray (100) so that the battery modules (10) can be partitioned. In this embodiment, four battery modules (10) are shown to be 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.

[0030] The pack cover (200) is provided to cover the upper part of the pack tray (100) and is a portion in which a venting gas discharge passage (210) is formed inside. The discharge passage (210) can be viewed as a type of discharge space or a retention or storage space, and although not shown, a partition, slit, or baffle member that guides or directs multiple discharge paths may be provided. In addition, when the pack tray (100) and the pack cover (200) are joined together, joining methods such as bolting, welding, bonding, or hooking may be applied.

[0031] A battery module (10) is enclosed in a module case (12, see FIG. 6) and accommodated inside a pack tray (100). A plurality of opening holes (11) are provided in both side sections on the upper surface of the module case (12), and venting gas is discharged when the battery module (10) ignites internally.

[0032] Meanwhile, there is an urgent need to improve the structure of the battery pack so that flames and high-temperature sparks from the battery module (10) that was initially ignited are not easily discharged to the outside of the battery module (10), while venting gas is easily discharged. Accordingly, in this embodiment, a double-structured top cover method is disclosed in which a top plate portion (300) is placed between the pack tray (100) and the pack cover (200) to provide a discharge passage at the top of the battery module (10).

[0033] FIG. 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 section view in the X-axis direction of the battery pack according to one embodiment of the present invention.

[0034] The top plate portion (300) is provided between the pack tray (100) and the pack cover (200), with its lower portion in contact with the battery module (10) and its upper portion communicating with the discharge passage (210), and can selectively discharge only the venting gas among the flame, high-temperature particles, and venting gas generated from the battery module (10).

[0035] To this end, the top plate portion (300) may include: a support frame (301) forming a frame-like structure; an upper plate and a lower plate (310, 320) each having a rim supported by the support frame (301) and having a venting hole (311, 321) through which the venting gas is discharged, and arranged overlapping each other; a flame blocking mesh layer (330) provided between the upper plate and the lower plate (310, 320) to block the discharge of flames or high-temperature particles; and a flame-retardant pad layer (340) disposed on the lower part of the lower plate (320).

[0036] The support frame (301) is a part that forms the framework of the top plate section (300). The support frame (301) is provided to accommodate the upper plate and the lower plate, and the support frame (301) is supported by being seated on the upper surface of the pack tray (100) and the internal partition (110). The support frame (301) is provided with a plurality of screw fastening holes (302) and is screw-coupled along the perimeter of the battery module (10) in the upper region of the battery module (10) through a fixing screw (350). Meanwhile, the support frame (301) in this embodiment may be provided with a material having excellent mechanical strength.

[0037] 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 received within the support frame (301). When received, the surface of the upper plate (310) is provided without a step difference relative to the height of the surface of the support frame (301), or the surface of the upper plate (310) may be configured to protrude or be recessed relatively for convenience in processing or assembly. Meanwhile, the upper plate (310) in this embodiment is provided with SUS material, which has the advantage of excellent heat absorption rate and thermal conductivity, as well as excellent durability against high-temperature venting gas or sparks.

[0038] The lower plate (320) also has substantially the same size and shape as the upper plate (310), and is made of SUS material.

[0039] A plurality of venting holes (311, 321) are provided on the plate surfaces of the upper plate and the lower plate (310, 320) at positions corresponding to the opening hole (11) of the aforementioned battery module (10). Venting gas can be ejected through the venting holes (311, 321).

[0040] Referring mainly to FIGS. 4 and FIGS. 6, the flame blocking mesh layer (330) is interposed between the upper plate and the lower plate (310, 320). That is, the flame blocking mesh layer (330) is provided between the upper plate and the lower plate (310, 320) and is provided to block the venting holes (311, 321). The flame blocking mesh layer (330) may be provided in a mesh structure and may be provided in a metal material that does not easily melt by heat. Accordingly, when flames, high-temperature particles, and venting gas generated from the battery module (10) are discharged through the opening hole (11) and ejected through the venting holes (311, 321), the flames, high-temperature particles, etc. are blocked by the flame blocking mesh layer (330), so that external ejection is blocked, and only the venting gas is selectively discharged.

[0041] Ultimately, even if flames, sparks, high-temperature particles, etc. are generated from the ignited battery module (10), they can be isolated inside the battery module (10) and prevented from leaking out, thereby minimizing thermal damage to other battery modules (10). In addition, venting gas, which requires risk management in terms of volume, can be easily discharged outside the battery module (10), thereby preventing or delaying thermal runaway of the battery pack.

[0042] The flame-retardant pad layer (340) is provided on the lower plate (320), facing the lower plate (320), and is positioned in close contact with the battery module (10). Here, the flame-retardant pad layer (340) may be a material with low thermal conductivity and excellent heat resistance (e.g., silicon, mica). When the flame-retardant pad layer (340) is interposed, in the event of internal ignition of the battery module (10), the heat, high-temperature particles, flames, etc. generated from the ignited battery module (10) are moved to the upper side of the battery module (10) and propagated to neighboring battery cells (111), thereby minimizing the spread.

[0043] In the flame-retardant pad layer (340) above, an exhaust slit (341) configured to tear when pressure exceeding the allowable pressure is applied is provided in an area corresponding to the venting hole (321) of the lower plate (320). The exhaust slit (341) is provided in a shape formed by making a dotted line in an H-shape or an I-shape. For example, when pressure exceeding the designed allowable pressure is applied to the ignited battery module (10), the exhaust slit (341) tears and venting gas is discharged.

[0044] Alternatively, the exhaust slit (341B) may be formed of a plurality of progressively increasing elliptical shapes, as shown in FIG. 10. In this case, the size of the exhaust slit (341B) that is cut differentially at pressures exceeding the designed allowable pressure may be varied, thereby changing the actual exhaust area of ​​the venting gas. For example, if the pressure is within a preset pressure range, the smallest elliptical exhaust slit (341B) may be cut off and the venting gas may be discharged, and if the pressure exceeds the preset pressure range, the intermediate elliptical or the largest elliptical exhaust slit (341B) may be cut off and a relatively large amount of venting gas may be discharged.

[0045] The above-mentioned top plate portion (300) can be connected to the pack tray (100) and the internal partition (110) by a fixing screw (350). Additionally, a sealing member (360) can be provided between the top plate portion (300) and the pack tray (100) so that the space between one battery module (10) and an adjacent battery module (10) can be completely isolated.

[0046] According to this embodiment, when the battery module (10) ignites internally, flames or high-temperature particles are not easily leaked out, while venting gas can be easily discharged out.

[0047] In addition, according to this embodiment, even if venting gas and sparks are generated from the ignited battery module (10), the thermal damage to other battery modules (10) can be minimized, thereby preventing or delaying thermal runaway of the battery pack.

[0048] FIG. 7 is a diagram illustrating the path through which venting gas is discharged via a passage in a battery pack according to one embodiment of the present invention.

[0049] Hereinafter, the discharge process in which venting gas is easily discharged to the outside according to the present embodiment will be explained in detail with reference to FIGS. 1 to 7.

[0050] First, as shown in FIG. 7, when internal ignition occurs in a specific battery module (10), the pressure inside the module case (12) of the battery module (10) increases, and accordingly, the pressure in the lower part of the flame-retardant pad layer (340) increases due to the venting gas discharged along the open hole (11).

[0051] Next, when the pressure rises above the design pressure, the discharge slit (341) of the flame-retardant pad layer (340) adjacent to the battery module (10) is torn and cut, and flames and high-temperature particles containing venting gas are ejected upward.

[0052] Next, due to the mesh structure of the flame blocking mesh layer (330) provided on the venting holes (311, 321) of the upper plate and lower plate (310, 320), venting gas passes through smoothly, while the discharge of flames or particle particles is blocked. Accordingly, flames or high-temperature particles are not easily leaked to the outside, while venting gas can be easily discharged to the outside, thereby minimizing thermal damage to other battery modules (10) and preventing or delaying thermal runaway of the battery pack.

[0053] Next, the venting gas that has passed through passes through the venting hole (311) of the upper plate (310) and is temporarily stored or flows into the discharge passage (210), and can be safely discharged to the outside through an additional discharge line, although not shown in the drawing. In this process, there is a possibility that the venting gas may flow into the neighboring battery module (10), but as shown in FIG. 7, the discharge slit (341) of the flame-retardant pad layer on the upper part of the neighboring battery module (10) is still blocked, so the inflow of the venting gas into the other battery module (10) can be completely blocked, thereby minimizing the thermal damage that the other battery modules (10) may receive.

[0054] Additionally, by securing the exhaust passage (210) in consideration of the volume of the venting gas, thermal damage to other battery modules (10) inside the battery pack can be delayed, and there is an advantage of being able to buy time for evacuation before thermal runaway.

[0055] Next, other embodiments of the battery module (10) of the present invention will be briefly described with reference to FIGS. 8 and 9.

[0056] 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 longitudinal 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.

[0057] Reference numbers identical to those in previous drawings indicate identical components. Duplicate descriptions of identical components will be omitted, and the explanation will focus on the differences from the previously described embodiments.

[0058] A battery module (10) according to another embodiment of the present invention has additional components in the flame-retardant pad layer (340) compared to the previously described embodiment. The flame-retardant pad layer (340) may be provided with an inlet section (342) that is tapered inward in the thickness direction to induce the inflow of the venting gas, and an outlet section (343) that is tapered and expanded to the inner diameter of the venting hole (311) on the side of the lower plate (320).

[0059] As illustrated in FIG. 8, the inlet section (342) is tapered inward in the thickness direction, thereby allowing the venting gas generated in the battery module (10) to be more easily drawn into the venting hole (321). The outlet section (343) is provided on the side of the lower plate (320) and is tapered and expanded to the inner diameter of the venting hole (311), thereby allowing for easier discharge into the venting hole (311) and the discharge passage (210).

[0060] Thus, the venting gas can be easily discharged to the outside through the exhaust passage (210), thereby minimizing thermal damage to other battery modules (10) and preventing or delaying thermal runaway of the battery pack.

[0061] In addition, compared to the first embodiment, the thickness or size of the discharge slit (341A) of the flame-retardant pad layer (340) of the second embodiment is relatively reduced, and accordingly, the cutting pressure range can be finely controlled, allowing for fine control in terms of gas discharge control according to the amount of venting gas discharged.

[0062] Meanwhile, the battery pack (1) according to the present invention may further include various devices for controlling the charging and discharging of battery modules (10), such as a Battery Management System (BMS), a current sensor, a fuse, etc., although not illustrated.

[0063] The battery pack (1) according to the present invention can be applied to a vehicle such as an electric vehicle or a hybrid vehicle. That is, the vehicle according to the present invention may include the battery pack (1) according to the present invention. The battery pack (1) may be installed in the vehicle body frame under the vehicle seat or in the trunk space, and when installed in the vehicle, the arrangement order of the battery pack may be reversed as needed.

[0064] In this specification, terms indicating directions such as up, down, left, right, front, and back have been used; however, these terms are used merely for convenience of explanation, and it is obvious to those skilled in the art that they may vary depending on the location of the object or the position of the observer.

[0065] As described above, although the present invention has been explained by limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs. Explanation of the symbols

[0066] 1 : Battery pack 10: Battery module 11: Open hole 12: Modular case 100: Pack tray 110: Internal bulkhead 200 : Pack cover 210 : Ejection passage 300: Top plate section 301: Support frame 302: Screw fastening hole 310: Upper plate 311 : Venting hole 320 : Lower plate 321: Venting hole 330: Flame barrier layer 340: Flame-retardant pad layer 341, 341A, 341B: Discharge slits 342: Inlet section 343: Outlet section 350 : Fixing screw 360 : Sealing member

Claims

Claim 1 A battery pack comprising: a pack tray provided to accommodate at least one battery module having a module case; a pack cover provided to cover the upper portion of the pack tray and having a venting gas discharge passage formed therein; and a top plate portion provided between the pack tray and the pack cover, wherein the lower portion faces the module case and the upper portion communicates with the discharge passage, and is configured to selectively discharge only the venting gas among the flame, high-temperature particles, and venting gas generated from the battery module, wherein the top plate portion comprises: a support frame forming a frame in the shape of a mold; an upper plate and a lower plate each having a rim supported by the support frame and having a venting hole through which the venting gas is discharged, and arranged to overlap each other; and a flame blocking mesh layer provided between the upper plate and the lower plate and blocking the discharge of the flame or high-temperature particles. Claim 2 delete Claim 3 A battery pack according to claim 1, wherein the top plate portion further comprises a flame-retardant pad layer disposed below the lower plate, and the flame-retardant pad layer is characterized by having a discharge slit configured to tear when a pressure greater than the allowable pressure is applied in an area corresponding to the venting hole of the lower plate. Claim 4 A battery pack according to claim 1, characterized in that the flame blocking mesh layer is provided in a mesh structure. Claim 5 A battery pack according to claim 1, wherein the pack tray is provided with an internal partition wall to partition the battery module, and the top plate portion is fixedly coupled to the pack tray and the internal partition wall. Claim 6 A battery pack according to claim 5, wherein the top plate portion is coupled to the pack tray and the inner partition with a fixing screw, and a sealing member is provided between the top plate portion and the pack tray. Claim 7 A battery pack according to claim 3, characterized in that the flame-retardant pad layer is provided with an inlet section that is tapered inward in the thickness direction to induce the inflow of the venting gas. Claim 8 A battery pack according to paragraph 3, characterized in that the flame-retardant pad layer is provided with an outlet section portion that is tapered and expanded by the inner diameter of the venting hole on the lower plate side. Claim 9 A battery pack characterized in that, in paragraph 3, the discharge slit is formed in a shape in which a sheath is made by creating an H-shaped dotted line. Claim 10 A battery pack according to paragraph 3, wherein the discharge slit is characterized by being composed of a plurality of progressively increasing elliptical shapes. Claim 11 An automobile characterized by including a battery pack according to any one of claims 1 and 3 through 10.

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