Battery pack case

Abstract

Disclosed herein is a battery pack case including a lower case formed with an accommodating space; a lower reinforcing plate installed in the accommodating space of the lower case and supporting at least one battery cell assembly; and an upper housing coupled to the lower housing to seal the accommodation space, in which the lower housing has a mechanical strength smaller than that of the lower reinforcing plate.

Description

Technical Field

[0001] The present disclosure relates to a battery pack housing in which a lower housing of the battery pack housing expands when thermal runaway occurs, so that even in a battery pack mounting structure where the upper margin space is extremely limited by a vehicle chassis, a rapid increase in internal pressure can be effectively suppressed.

[0002] This application claims the benefit of priority of Korean Patent Application No. 10-2023-0125115 filed on September 19, 2023 and Korean Patent Application No. 10-2024-0125621 filed on September 13, 2024, and the entire contents of Korean Patent Application No. 10-2023-0125115 and Korean Patent Application No. 10-2024-0125621 are incorporated herein by reference. Background Art

[0003] Unlike primary batteries, secondary batteries can be recharged, and due to their potential for miniaturization and large capacity, extensive research and development have been conducted on secondary batteries in recent years. In addition, with technological development and the increasing demand for mobile devices, due to the growing emphasis on electric vehicles and energy storage systems that respond to current environmental protection needs, the demand for secondary batteries as an energy source has increased rapidly.

[0004] Based on the shape of the battery housing, secondary batteries are classified into button-type batteries, cylindrical batteries, square batteries, and pouch-type batteries. In a secondary battery, an electrode assembly installed inside the battery housing is an element that can generate electricity by charging and discharging and has a laminated structure including electrodes and a separator.

[0005] Since secondary batteries need to be used continuously for a long time, it is necessary to effectively control the heat generated during the charging and discharging process. When a secondary battery is not properly cooled, an increase in temperature causes an increase in current, and an increase in current causes the temperature to rise again, resulting in a positive feedback chain reaction, ultimately leading to a catastrophic situation of thermal runaway.

[0006] In addition, when a secondary battery includes a group in the form of a battery cell assembly such as a module or a battery pack, a thermal propagation phenomenon occurs in which thermal runaway in any one secondary battery causes other adjacent secondary batteries to overheat continuously. In other words, when thermal runaway occurs in a battery cell assembly in a battery pack, a large amount of conductive dust, gas, and flame are ejected from the high-voltage terminal of the battery cell assembly, and thus, the dust accumulates on the high-voltage terminals of other adjacent battery cell assemblies, and the thermal propagation phenomenon is triggered by the heat transfer of the gas and the flame.

[0007] When thermal propagation occurs in the battery pack, the internal pressure and temperature of the battery pack rapidly increase. In response to such increases in pressure and temperature, the battery pack should maintain the structural integrity for a considerable period of time. When the battery pack undergoes structural collapse and outside air flows in, the combustion reaction is rapidly activated, leading to risks such as fires and explosions outside the battery pack with a large amount of electricity.

[0008] The cover on the upper surface of the battery pack housing of the sealed battery pack is usually made of a metal plate with a thickness thinner than that of other surfaces of the battery pack housing. This enables the cover to expand in response to a rapid increase in internal pressure in cases such as when thermal propagation occurs, so as to slow down the pressure increase. When the pressure increase is delayed due to the expansion of the cover, the exhaust device installed on the battery pack housing operates to achieve normal pressure discharge. In other words, the expansion of the cover caused by the internal pressure provides the start-up time required for the stable operation of the exhaust device.

[0009] However, when the battery pack is installed on the chassis of an electric vehicle, various vehicle structures provided on the upper surface of the battery pack usually only provide a very limited margin space. In this case, when thermal propagation occurs, the expansion of the cover is spatially restricted, whereby the internal pressure of the battery pack housing does not increase sufficiently, thus accelerating the thermal propagation phenomenon, or the battery pack housing may cause the structure to collapse too quickly, leading to serious safety problems such as fires or explosions. Therefore, there is a need to provide a method that can appropriately slow down the increase in the internal pressure of the battery pack housing at the initial stage even when the margin space above the battery pack is narrow. Summary of the Invention

[0010] Technical Problem

[0011] An object of the present disclosure is to provide a battery pack housing that can effectively suppress a rapid increase in internal pressure caused by thermal runaway even in a battery pack installation structure with extremely limited margin space for cover expansion on the vehicle chassis.

[0012] However, the technical problems to be solved by the present disclosure are not limited to the above problems, and those skilled in the art can clearly understand other problems not mentioned according to the description of the present disclosure described below.

[0013] Technical Solution

[0014] The present disclosure relates to a battery pack housing. In one example, the battery pack housing includes a lower housing formed with an accommodation space; a lower reinforcing plate installed in the accommodation space of the lower housing and supporting at least one battery cell assembly; and an upper housing combined with the lower housing to seal the accommodation space, wherein the mechanical strength of the lower housing is less than that of the lower reinforcing plate.

[0015] The lower reinforcing plate may include a side wall in contact with the lower housing and a bottom plate formed with at least one ventilation hole.

[0016] The pressure in the sealed accommodation space can be applied to the lower housing through the ventilation holes of the lower reinforcing plate.

[0017] In one embodiment, the side wall of the lower reinforcing plate may be joined to the lower housing.

[0018] In addition, at least a part of the lower reinforcing plate around the ventilation holes of the bottom plate may form a gap relative to the lower housing.

[0019] The plurality of ventilation holes may include corner holes formed by cutting the corners of the lower reinforcing plate.

[0020] In addition, the plurality of ventilation holes may further include inner holes formed by partially cutting the interior of the lower reinforcing plate.

[0021] Here, a plurality of battery cell assemblies may be provided, and the inner holes may be formed between adjacent battery cell assemblies.

[0022] According to such a battery pack housing of the present disclosure, when thermal runaway occurs in the battery cell assembly, resulting in an increase in internal pressure, the increased pressure is applied to the lower housing, and the lower housing expands to relieve the increase in pressure.

[0023] Meanwhile, according to an embodiment of the present disclosure, a foaming refractory coating may be applied between the lower housing and the lower reinforcing plate.

[0024] The foaming refractory coating may undergo volume expansion through the high-temperature gas flowing in through the ventilation holes, forming a heat-insulating layer that fills the space of the lower housing expanded due to the increase in internal pressure.

[0025] In one embodiment, the lower reinforcing plate may be in the form of a flat plate without a side wall, and the edge of the bottom plate formed with at least one ventilation hole may be joined or bonded to the lower housing.

[0026] The bottom surface of the lower housing includes an annular edge portion and a stepped bottom surface extending in an outwardly protruding form relative to the edge portion, wherein the edge of the lower reinforcing plate may be joined or bonded to the edge portion.

[0027] In one embodiment, the battery cell assembly has a lower exhaust structure, wherein the lower reinforcing plate includes a bottom plate formed with at least one ventilation hole, and the ventilation holes may be arranged in alignment facing the exhaust device provided in the battery cell assembly.

[0028] In one embodiment, the thickness of the bottom surface of the lower housing may be thinner than that of the side surface.

[0029] In one embodiment, the lower housing may have an annular side surface and a bottom surface in the form of a flat plate that are separately manufactured and joined to each other.

[0030] The thickness of the bottom surface of the two-piece lower housing may be thinner than that of the side surface.

[0031] The side surface and the bottom surface of the lower housing may include different materials.

[0032] Advantageous Effects

[0033] Therefore, the battery pack housing of the present disclosure includes a dual structure having a lower reinforcement plate that supports the battery cell assembly and a lower housing having a lower rigidity than the lower reinforcement plate. Thus, when thermal runaway occurs in the battery pack housing and the internal pressure rapidly increases, the pressure is applied to the lower housing through the vent holes in the lower reinforcement plate, and the pressurized lower housing can expand.

[0034] The internal pressure increased due to the volume expansion of the lower housing is relieved, and stable pressure discharge is obtained by delaying the rapid pressure increase while operating the exhaust device. Therefore, the battery pack housing of the present disclosure can prevent the structural collapse of the battery pack housing by appropriately slowing down the pressure increase at the initial stage of thermal runaway. In particular, since the lower housing of the battery pack housing of the present disclosure includes an expansion structure, it can be applied to electric vehicles that provide very limited space for the upper surface of the battery pack housing due to various structures.

[0035] However, the technical effects that can be obtained by the present disclosure are not limited to the above effects, and those skilled in the art can clearly understand other effects not mentioned based on the description of the present disclosure described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The following drawings attached to this specification illustrate exemplary embodiments of the present disclosure and, together with the detailed description of the present invention described below, are used to further understand the technology of the present invention. Therefore, the present invention should not be construed as being limited to the description of these drawings.

[0037] Figure 1 is a perspective view of a battery pack housing according to an embodiment of the present disclosure.

[0038] Figure 2 is Figure 1 an exploded perspective view of the battery pack housing.

[0039] Figure 3 is a plan view of the battery pack housing with the upper housing removed.

[0040] Figure 4 is along Figure 1 the "A-A" line of

[0041] Figure 5 is a diagram showing Figure 4 another embodiment.

[0042] Figure 6 is a diagram showing the lower housing when thermal runaway occurs.

[0043] Figure 7 is a cross-sectional view according to another embodiment of the present disclosure.

[0044] Figure 8 is a diagram showing Figure 7 the lower housing of the battery pack housing when thermal runaway occurs.

[0045] Figure 9 is a diagram showing an embodiment of a battery pack housing including a lower reinforcing plate in a flat plate form.

[0046] Figure 10 is a diagram showing an embodiment of a battery pack housing in which the bottom surface of the lower housing forms a two-step structure.

[0047] Figure 11 is a diagram showing an embodiment of a battery pack housing suitable for accommodating a battery cell assembly having a lower exhaust structure.

[0048] Figure 12 is a diagram showing an embodiment of a battery pack housing having a structure of a bottom surface with a thickness thinner than that of the side surface of the lower housing.

[0049] Figure 13 is a diagram showing an embodiment of a battery pack housing in which the lower housing includes a two-piece structure. Detailed Description

[0050] Since the present disclosure can have various modifications and various embodiments, specific embodiments of the present disclosure will be described in detail below.

[0051] However, it should be understood that the present disclosure is not limited to specific embodiments, but includes all modifications, equivalents, or alternatives within the spirit and technical scope of the present disclosure.

[0052] The terms "including", "comprising", and "having" used herein indicate the presence of features, quantities, steps, actions, components, or elements described in this specification, or combinations thereof, and it should be understood that the possibility of the presence or addition of one or more other features, quantities, steps, actions, components, elements, or combinations thereof is not precluded in advance.

[0053] In addition, in the present disclosure, when a part of a layer, film, region, plate, etc. is disposed "on" another part, this includes not only the case where a part is disposed "directly" on another part, but also the case where yet another part is interposed therebetween. Conversely, when a part of a layer, film, region, plate, etc. is disposed "under" another part, this includes not only the case where a part is disposed "directly" under another part, but also the case where yet another part is interposed therebetween. In addition, in the present disclosure, "on..." can include not only the case of being disposed on the upper part, but also the case of being disposed on the lower part.

[0054] In one example, the present disclosure relates to a battery pack housing including a lower housing having an accommodation space formed therein, a lower reinforcement plate installed in the accommodation space of the lower housing and supporting at least one battery cell assembly, and an upper housing coupled to the lower housing to seal the accommodation space, wherein a mechanical strength of the lower housing is less than a mechanical strength of the lower reinforcement plate.

[0055] In addition, the pressure of the sealed accommodation space can be applied to the lower housing through the vent holes of the lower reinforcement plate.

[0056] Therefore, the battery pack housing of the present disclosure includes a dual structure of a lower reinforcement plate supporting the battery cell assembly and a lower housing having a lower rigidity than the lower reinforcement plate. Therefore, when thermal runaway occurs in the battery pack housing and the internal pressure rapidly increases, pressure is applied to the lower housing through the vent holes in the lower reinforcement plate, and the pressurized lower housing can expand.

[0057] Since the internal pressure increased by the volume expansion of the lower housing is relieved, and stable pressure discharge is obtained by delaying a sudden pressure increase while operating the exhaust device, and by appropriately relieving the initial pressure increase, the structural collapse of the battery pack housing can be prevented. In particular, since the lower housing is formed with an expansion structure, the battery pack housing of the present disclosure can be applied to an electric vehicle that provides a very limited margin space toward the upper surface of the battery pack housing due to various structures provided.

[0058] [Detailed Description]

[0059] Hereinafter, specific embodiments of the battery pack housing 10 according to the present disclosure will be described in detail with reference to the accompanying drawings. As a reference, unless otherwise specified, the directions of front, rear, upper, lower, left, and right for representing relative positions in the following description are for the purpose of understanding the present disclosure and refer to the directions as shown in the figures.

[0060] [First Embodiment]

[0061] Figure 1 is a perspective view of a battery pack housing 10 according to an embodiment of the present disclosure, and Figure 2 isFigure 1 Exploded perspective view of the battery pack housing 10. Referring to the accompanying drawings, the battery pack housing 10 of the present disclosure may include a lower housing 100, a lower reinforcement plate 200, and an upper housing 300.

[0062] The lower housing 100 and the upper housing 300 are joined to each other to form at least one sealed accommodation space. In particular, the lower housing 100 may form an accommodation space large enough to accommodate at least the lower reinforcement plate 200 and a plurality of battery cell assemblies 500. In the illustrated embodiment, the lower housing 100 and the upper housing 300 are respectively shown as being split in half to form an accommodation space. However, this is an exemplary embodiment, and the upper housing 300 may be configured in the form of a flat cover. In this case, the lower housing 100 may form most of the accommodation space of the battery pack housing 10.

[0063] As used herein, the battery cell assembly 500 refers to a collection in which a plurality of secondary battery cells are structurally joined together as a unit. As used herein, the fact that a plurality of secondary battery cells are structurally joined together as a unit does not mean that it is to be construed as having a limited meaning of being separated from each other by a structure such as a housing, but rather means that the battery cell assembly 500 has a meaning of being structurally independent of each other and distinguishable from each other. Therefore, according to a specific embodiment, the battery cell assembly 500 may also be referred to as a battery module, a battery block, etc. and have a more general meaning. Additionally, in the accompanying drawings, for ease of description and illustration, the shapes of the battery cell assembly 500 and the battery cell 510 are depicted as simple squares, but this is merely an example. Therefore, the battery pack housing 10 of the present disclosure should not be construed as being limited to any specific form factor, such as, for example, a button cell, a cylindrical cell, a square cell, a pouch cell, etc.

[0064] The lower reinforcement plate 200 is a structure that supports at least one battery cell assembly 500. The lower reinforcement plate 200 is installed in the accommodation space of the lower housing 100. For example, the lower reinforcement plate 200 may include a side wall 210 that contacts the lower housing 100 and a bottom plate 220 that supports the battery cell assembly 500. In order to stably install the lower reinforcement plate 200, the side wall 210 of the lower reinforcement plate 200 may be joined to the lower housing 100. However, the bottom plate 220 of the lower reinforcement plate 200 is not joined to the lower housing 100. In other words, the bottom plate 220 of the lower reinforcement plate 200 is separated from the inner surface of the lower housing 100.

[0065] In addition, the mechanical strength of the lower housing 100 is less than that of the lower reinforcement plate 200. For example, the thickness of the lower housing 100 can be thinner than that of the lower reinforcement plate 200. Alternatively, the material of the lower housing 100 can be more ductile than that of the lower reinforcement plate 200. Alternatively, the lower housing 100 can be thinner and more ductile in terms of both thickness and material. Therefore, when the same force is applied, the lower housing 100 deforms more and earlier than the lower reinforcement plate 200. Therefore, the statement that the mechanical strength of the lower housing 100 as referred to herein is less than that of the lower reinforcement plate 200 should be broadly understood to mean that when the internal pressure of the battery pack housing 10 increases, the lower housing 100 expands more easily than the lower reinforcement plate 200.

[0066] Referring Figure 2 and Figure 3 , at least one ventilation hole 230 is formed in the bottom plate 220 of the lower reinforcement plate 200. The ventilation holes 230 serve as channels communicating with each other, and the accommodation space is divided into two by the lower reinforcement plate 200. For example, when a thermal runaway occurs in any battery cell assembly 500 supported on the lower reinforcement plate 200, resulting in an increase in internal pressure, the increased pressure is applied to the lower housing 100 through the ventilation holes 230.

[0067] The ventilation holes 230 need to be configured such that when a thermal runaway occurs in any battery cell 510 of the battery cell assemblies 500 installed in the battery pack housing 10, or when a thermal runaway occurs in any of the battery cell assemblies 500 with multiple battery cell assemblies 500 installed, the resulting increased pressure and high-temperature gas are quickly transmitted to the lower housing 100. For this purpose, a plurality of ventilation holes 230 can be provided.

[0068] Figure 3 An exemplary form in which a plurality of ventilation holes 230 are provided is shown. The plurality of ventilation holes 230 can include corner holes 232 formed by cutting the corners of the lower reinforcement plate 200. Considering the symmetric arrangement, there can be a plurality of corner holes 232, and they can be formed at each of the four corners of the lower reinforcement plate 200. Since cutting the corners of the lower reinforcement plate 200 has a relatively small impact on the structural rigidity for stably supporting the battery cell assemblies 500, the corner holes 232 are formed at the corners of the lower reinforcement plate 200.

[0069] Alternatively, in some embodiments, as Figure 3As shown, a plurality of vent holes 230 may include inner holes 234 that partially cut into the interior of the lower reinforcement plate 200. This is because the corner holes 232 are located at the corners of the lower reinforcement plate 200, which may cause a time delay in the flow of high-temperature gas towards the lower housing 100 when thermal runaway occurs in the central region. In this case, considering the inner holes 234, the rigidity of the lower reinforcement plate 200 may need to be designed to be sufficient to support the battery cell assembly 500. For example, when a plurality of battery cell assemblies 500 are installed, a plurality of inner holes 234 may be uniformly formed in a symmetric form that penetrates between adjacent battery cell assemblies 500.

[0070] Figure 4 is a cross-sectional view taken along the Figure 1 "A - A" line of Figure 4 . Referring to

[0071] Figure 6 is a view showing the lower housing during thermal runaway, and when thermal runaway occurs in the battery cell assembly 500 installed in the battery pack housing 10, causing an increase in high-temperature gas and internal pressure, the increased pressure can be applied to the bottom surface of the lower housing 100 through the corner holes 232 of the lower reinforcement plate 200. As described above, the mechanical strength of the lower housing 100 is less than that of the lower reinforcement plate 200. Therefore, as Figure 6 shown, the lower housing 100 with lower rigidity expands under pressure, and the increase in the internal pressure of the battery pack housing 10 can be relieved to the extent of the volume increase due to the expansion of the lower housing 100.

[0072] Stable pressure discharge is obtained by delaying the rapid pressure increase due to the volume increase caused by the expansion of the lower housing 100 while operating the exhaust device (not shown), and by appropriately slowing down the pressure increase at the initial stage of thermal runaway to prevent the structural collapse of the battery pack housing 10. In particular, as Figure 6 exemplarily shown, since the battery pack housing 10 of the present disclosure has a structure in which the lower housing 100 expands, the battery pack housing 10 can be applied to cases where there is almost no margin space on the upper surface of various structural battery pack housings. For example, the battery pack housing 10 of the present disclosure is suitable as the housing of a battery pack installed at the lower part of the chassis of an electric vehicle (i.e., a battery pack installed such that the upper housing 300 faces the chassis of the electric vehicle and the lower housing 100 faces the ground).

[0073] Meanwhile, Figure 5 is a view showing Figure 4 another embodiment of Figure 5In the embodiment, the side wall 210 of the lower reinforcing plate 200 is joined to the lower housing 100, and the bottom plate 220 of the lower reinforcing plate 200 contacts the lower housing 100. Since the bottom plate 220 of the lower reinforcing plate 200 contacts and is supported by the lower housing 100, the lower housing 100 with relatively weak rigidity is less likely to be damaged, deformed, or generate abnormal noise. However, the bottom plate 220 of the lower reinforcing plate 200 and the lower housing 100 are adhesively bonded, and pressure release through the vent hole 230 may not occur smoothly. To solve this problem, as Figure 5 shown in the partial enlarged view, at least a part of the area around the vent hole 230 of the bottom plate 220 may be formed with a gap 236 relative to the lower housing 100. Such a gap 236 can facilitate the flow of internal pressure toward the lower housing 100. Such an arrangement of the gap 236 formed around the vent hole 230 is an exemplary embodiment, and when the bottom plate 220 of the lower reinforcing plate 200 and the lower housing 100 are not joined to each other, the gap 236 structure may not exist.

[0074] [Second Embodiment]

[0075] Therefore, according to the battery pack housing 10 of the present disclosure, when thermal runaway occurs in the installed battery cell assembly 500, resulting in an increase in internal pressure, the increased pressure is applied to the lower housing 100 through the vent hole 230, and the pressurized lower housing 100 expands to expand the internal space to relieve the pressure increase.

[0076] The lower housing 100 (particularly, the bottom surface of the lower housing 100) designed to have relatively weak rigidity is mainly made to have a relatively thin thickness. Due to the thin thickness, it can easily expand in response to an increase in internal pressure. However, during thermal runaway, in addition to the increase in the internal pressure of the battery pack housing, the high-temperature gas generates a considerable amount of heat. The high-temperature gas also flows toward the bottom surface of the lower housing 100 through the vent hole 230 of the lower reinforcing plate 200. When the bottom surface of the lower housing 100 expands due to pressure, more high-temperature gas accumulates in the expanded space, which causes the bottom surface of the lower housing 100 to become high-temperature. Therefore, the lower housing 100 of the battery pack housing 10 can serve as a heat source for an external fire.

[0077] The second embodiment of the present disclosure further includes a configuration for effectively suppressing the application of high temperature to the outside through the lower housing 100 when the bottom surface of the lower housing 100 expands due to thermal runaway. Figure 7 A cross-sectional view of the lower reinforcing plate 200 and the lower housing 100 according to the second embodiment of the present disclosure is shown.

[0078] Referring to Figure 7, the foaming refractory coating 400 is coated between the lower housing 100 and the lower reinforcement plate 200. The foaming refractory coating 400 has the property of foaming when exposed to heat and can be a dry coating under normal conditions. When the dry coating of such a foaming refractory coating 400 foams due to heat, the dry coating can turn into a heat-insulating layer (e.g., a carbonized layer) that expands dozens of times in volume. The expanded heat-insulating layer can delay heat transfer for a predetermined period of time.

[0079] Figure 8 is a diagram showing the lower housing 100 of the battery pack housing 10 when thermal runaway occurs Figure 7 When the foaming refractory coating 400 is coated between the lower housing 100 and the lower reinforcement plate 200, since the lower housing 100 expands due to pressure when thermal runaway occurs, the foaming refractory coating 400 is exposed to the high-temperature gas flowing in through the vent hole 230. Therefore, the foaming refractory coating 400 expands dozens of times in volume due to heat, thereby forming a heat-insulating layer 410 that fills the space of the expanded lower housing 100 due to the increase in internal pressure.

[0080] The foamed heat-insulating layer 410 generated by the foaming refractory coating 400 does not prevent pressure from being applied to the lower housing 100. Instead, it can provide isolation for the high-temperature gas gathered in the expanded lower housing 100, thereby preventing the battery pack housing 10 from being used as a heat source and causing an external fire in its surrounding environment.

[0081] [Third Embodiment]

[0082] Figure 9 shows another embodiment of the battery pack housing 10 of the present disclosure. In Figure 9 this embodiment, the lower reinforcement plate 200 includes a bottom plate 220 without side walls 210. In other words, except for not having side walls 210, the lower reinforcement plate 200 is in the form of a flat plate, and its configuration includes vent holes 230. In other words, there can be multiple vent holes 230, and they can include corner holes 232 and / or inner holes 234.

[0083] The edge of the flat-plate-shaped lower reinforcement plate 200 is joined to the lower housing 100. For example, multiple welding points 240 can be formed along the edge of the lower reinforcement plate 200 by spot welding. Except for the welding points 240, the rest of the lower reinforcement plate 200 is joined to the lower housing 100 but not adhesively bonded to the lower housing 100. Therefore, as Figure 6 shown, when thermal runaway occurs in the battery cell assembly 500 installed in the battery pack housing 10, resulting in an increase in high-temperature gas and internal pressure, the lower housing 100 may expand due to the increase in pressure.

[0084] Here, the edge of the lower reinforcement plate 200 is described as being joined to the lower housing 100 by spot welding, but it may also be joined by continuous welding instead of spot welding, or by other fastening mechanisms such as bolts or rivets.

[0085] Figure 10 Another embodiment of the battery pack housing 10 with the lower reinforcement plate 200 in a flat plate form is shown. In Figure 10 this embodiment, the lower housing 100 has a two-step structure where the bottom surface 110 includes an annular edge portion 112 and a stepped bottom surface 114 that extends in an outwardly protruding form relative to the edge portion 112. In the lower housing 100 having such a two-step structure, the annular edge portion 112 is the area where the edge of the flat plate-shaped lower reinforcement plate 200 is joined or coupled, and the stepped bottom surface 114 corresponds to the area of the bottom surface 110 of the lower housing 100 that expands due to an increase in internal pressure. The stepped bottom surface 114 forms a gap relative to the bottom plate 220 of the lower reinforcement plate 200, and such a gap can facilitate the application of pressure through the vent hole 230.

[0086] [Fourth Embodiment]

[0087] Figure 11 FIG. is a diagram showing an embodiment of a battery pack housing 10 suitable for accommodating a battery cell assembly 500 having a lower exhaust structure. Here, the battery cell assembly 500 having a lower exhaust structure may refer to an exhaust device 512 provided in one or more battery cells 510 including the battery cell assembly 500, such as a battery cell assembly 500 having a rupture disk provided at the lower part facing the lower housing 100. Alternatively, even if the exhaust device provided in the battery cell 510 can be provided on a surface other than the bottom surface (e.g., the upper surface), it may also refer to an exhaust structure such that the exhaust device provided in the battery cell assembly 500 is provided on the bottom surface facing the lower housing 100, ultimately causing high-pressure gas to be released towards the lower housing 100. Although Figure 11 FIG. shows the exhaust device 512 of the battery cell 510 provided on the bottom surface, but this should be understood as an exemplary embodiment, and the battery cell assembly 500 itself may be provided with an exhaust device having a lower exhaust structure that conforms to the above definition.

[0088] Referring to Figure 11, the formation position of the inner hole 234 provided inside the vent hole 230 of the lower reinforcement plate 200 is aligned so as to face the exhaust device 512 of the battery cell 510 included in the battery cell assembly 500. Therefore, when the exhaust device 512 of the battery cell 510 operates to relieve high-pressure gas, at least a part of the gas pressure can be directly applied to the bottom surface 110 of the lower housing 100. Immediate and direct pressure release can cause the bottom surface 110 of the lower housing 100 to expand and deform in a shorter period of time, thereby causing pressure release at an early stage when the pressure inside the battery pack housing 10 increases.

[0089] As Figure 11 shown, the arrangement of the vent hole 230 considering the lower exhaust structure in the lower reinforcement plate 200 is applicable to the above first to third embodiments.

[0090] [Fifth Embodiment]

[0091] Figure 12 And Figure 13 are diagrams showing different embodiments of the lower housing 100. Specifically, Figure 12 relates to an embodiment in which the side surface 120 and the bottom surface 110 of the lower housing 100 have different thicknesses, and Figure 13 relates to an embodiment of a two-piece structure in which the side surface 120 and the bottom surface 110 of the lower housing 100 are separated from each other.

[0092] Referring to Figure 12 , a structure of the bottom surface 110 having a thickness thinner than that of the side surface 120 of the lower housing 100 can be obtained. By forming the bottom surface 110 of the lower housing 100 with a thinner thickness, this only relatively reduces the mechanical strength of the bottom surface and makes it easier to maintain the favorable overall mechanical strength of the lower housing 100. For example, by using a pressing process of a mold, the lower housing 100 having an integrated structure and the thickness of the bottom surface 110 thinner than that of the side surface 120 can be manufactured.

[0093] Referring to Figure 13 , in the embodiment, the side surface 120 and the bottom surface 110 can also be manufactured as separate components and then combined with each other to complete the lower housing 100. According to such a two-piece structure, the lower housing 100 includes an annular side surface 120 and a bottom surface 110 in the form of a flat plate, and the bottom surface 110 is combined with the edge portion of the annular side surface 120 to form the lower housing 100.

[0094] According to Figure 13 's embodiment, the process of combining the annular side surface 120 and the bottom surface 110 in the form of a flat plate is added, but the lower housing 100 has the advantage of increased design freedom. For example, in order to make the mechanical strength of the bottom surface 110 smaller than that of the side surface 120, it is easy to manufacture the thickness of the bottom surface 110 thinner than Figure 12The side surface 120 of the lower housing 100 has a thin structure. Alternatively, the bottom surface 110 and the side surface 120 of the lower housing 100 can be made of different materials. Alternatively, the side surface 120 can be made of an extruded molded product with a hollow member reinforced with ribs to reduce weight and ensure rigidity, while the bottom surface 110 can be made of a conventional metal plate.

[0095] The lower housing 100 has Figure 13 a two-piece structure, and when the side surface 120 and the bottom surface 110 are combined, a sealed joint needs to be obtained. This is because the overall airtightness of the battery pack housing 10 needs to be maintained. A sealed joint between the side surface 120 and the bottom surface 110 of the lower housing 100 can be obtained by welding. For example, the side surface 120 and the bottom surface 110 can be joined to each other by continuous welding. Alternatively, a combination of a structural joint such as a bolt or a rivet and an airtight joint such as brazing can be used.

[0096] As described above, the present disclosure has been described in more detail with reference to the drawings and embodiments. However, since the configurations described in the drawings or embodiments herein are only one embodiment of the present disclosure and do not represent the overall technical spirit of the present disclosure, it should be understood that the present disclosure covers various equivalents, modifications, and substitutions at the time of filing this application.

[0097] [Description of Reference Numerals]

[0098] 10: Battery pack housing

[0099] 100: Lower housing

[0100] 110: Bottom surface

[0101] 112: Edge portion

[0102] 114: Step-shaped bottom surface

[0103] 120: Side surface

[0104] 200: Lower reinforcement plate

[0105] 210: Side wall

[0106] 220: Bottom plate

[0107] 230: Vent hole

[0108] 232: Corner hole

[0109] 234: Inner hole

[0110] 236: Gap

[0111] 240: Welding point

[0112] 300: Upper housing

[0113] 400: Foaming refractory coating

[0114] 410: Thermal insulation layer (foaming foam layer)

[0115] 500: Battery cell assembly

[0116] 510: Battery cell

[0117] 512: Exhaust device

Claims

1. A battery pack housing, comprising: A lower shell body, forming a receiving space; a lower reinforcing plate installed in the accommodation space of the lower housing and supporting at least one battery cell assembly; as well as an upper shell, combined with the lower shell to seal the accommodation space, Wherein, the mechanical strength of the lower shell is smaller than the mechanical strength of the lower reinforcing plate.

2. The battery pack housing according to claim 1, wherein: The lower reinforcing plate includes a side wall in contact with the lower housing and a bottom plate formed with at least one vent hole.

3. The battery pack housing according to claim 2, wherein: The pressure of the sealed accommodation space is applied to the lower case through the vent holes of the lower reinforcement plate.

4. The battery pack housing according to claim 2, wherein: The side wall of the lower reinforcement plate is engaged with the lower case.

5. The battery pack housing according to claim 4, wherein: At least a portion of the lower reinforcement plate around the vent hole of the bottom plate forms a gap with respect to the lower case.

6. The battery pack housing according to claim 2, wherein: The plurality of ventilation holes include corner holes formed by cutting corners of the lower reinforcement plate.

7. The battery pack housing according to claim 6, wherein: The plurality of ventilation holes further include inner holes formed by partially cutting open an interior of the lower reinforcement plate.

8. The battery pack housing according to claim 7, wherein: The battery cell assembly is provided in plurality, and the inner hole is formed between adjacent battery cell assemblies.

9. The battery pack housing according to claim 3, wherein: When thermal runaway occurs in the battery cell assembly, causing internal pressure to increase, the increased pressure is applied to the lower case, and the lower case expands to relieve the pressure increase.

10. The battery pack housing according to claim 9, wherein: A foaming fire-resistant coating is coated between the lower shell and the lower reinforcing plate.

11. The battery pack housing according to claim 10, wherein: The foamable refractory paint expands in volume due to the high-temperature gas flowing in through the vent holes, thereby forming a heat insulating layer that fills the space of the lower shell that expands due to the increase in internal pressure.

12. The battery pack housing according to claim 1, wherein: The lower reinforcing plate is in the form of a flat plate without a side wall, and an edge of a bottom plate formed with at least one vent hole is joined or combined with the lower shell.

13. The battery pack housing according to claim 12, wherein: The bottom surface of the lower shell includes an annular edge portion and a stepped bottom surface extending outwardly from the edge portion. Wherein, the edge of the lower reinforcing plate is joined or combined with the edge portion.

14. The battery pack housing according to claim 1, wherein: The battery cell assembly has a lower exhaust structure, Wherein, the lower reinforcing plate comprises a bottom plate formed with at least one vent hole, The vent hole is arranged in an aligned manner to face the exhaust device provided in the battery cell assembly.

15. The battery pack housing according to claim 1, wherein: The bottom surface of the lower shell is thinner than the side surface.

16. The battery pack housing according to claim 1, wherein: The lower housing has an annular side surface and a flat plate-shaped bottom surface that are manufactured separately and combined with each other.

17. The battery pack housing according to claim 16, wherein: The bottom surface of the lower case is thinner than the side surface.

18. The battery pack housing according to claim 16, wherein: The side surface and the bottom surface of the lower housing include different materials.

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