Battery module and battery pack including same

Abstract

A battery module according to an embodiment of the present invention comprises: a battery cell assembly formed by stacking a plurality of battery cells; a module frame for accommodating the battery cell assembly, the module frame comprising a bottom portion; and a phase change material layer disposed on the lower portion of the battery cell assembly. The phase change material layer is configured such that a portion thereof corresponding to a battery cell experiencing an over-high temperature phenomenon among the plurality of battery cells is melted and removed, and a bottom portion thereof is opened by the eliminated portion of the phase change material layer, thereby causing the battery cell experiencing the over-high temperature phenomenon to be discharged.

Description

TECHNICAL FIELD

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0168581, filed on November 28, 2023, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference.

[0003] The present application relates to a battery module and a battery pack including the same, and more particularly, the present application relates to a battery module capable of effectively handling temperature rise of one battery cell within the battery module, and a battery pack including the same. BACKGROUND

[0004] In modern society, as the use of portable devices such as mobile phones, laptop computers, camcorders, and digital cameras has become widespread, the development of technology related to mobile devices is becoming active. In addition, as a solution to the problem of air pollution caused by existing gasoline vehicles using fossil fuels, secondary batteries capable of repeated charging and discharging are being used as power sources for electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (P-HEVs), and the like, and the demand for the development of secondary batteries is increasing.

[0005] Currently commercially available secondary batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries are attracting attention due to their advantages of having no memory effect compared to nickel-based secondary batteries, being capable of free charging and discharging, having a very low self-discharge rate, and having a high energy density.

[0006] Such a lithium secondary battery mainly uses a lithium-based oxide and a carbon material as a positive electrode active material and a negative electrode active material, respectively. The lithium secondary battery includes an electrode assembly in which a positive electrode plate and a negative electrode plate each coated with a positive electrode active material and a negative electrode active material are provided with a separator between the positive electrode plate and the negative electrode plate, and a battery case that seals and accommodates the electrolyte and the electrode assembly together.

[0007] In general, depending on the shape of the outer packaging material, lithium secondary batteries can be classified into can-type secondary batteries in which an electrode assembly is embedded in a metal can, and pouch-type secondary batteries in which an electrode assembly is embedded in a pouch made of an aluminum laminate sheet.

[0008] Recently, secondary batteries are widely used not only for small devices such as portable electronic devices, but also for medium and large devices such as vehicles and power storage devices. For applications in medium and large devices, a large number of secondary batteries can be electrically connected to increase capacity and output. In this case, pouch-type secondary batteries become more widely used due to their advantages such as easy stacking and light weight.

[0009] In the case of a secondary battery for a small device, two or three battery cells are arranged, but in the case of a secondary battery for a medium to large device such as a vehicle, a battery module having a plurality of battery cells electrically connected is used. Such a battery module improves capacity and output by forming a battery cell assembly having a plurality of battery cells connected in series or in parallel. In addition, one or more battery modules can be installed together with various control and protection systems such as a battery disconnect unit (BDU), a battery management system (BMS), and a cooling system to form a battery pack.

[0010] As described above, in the case of a battery module and a battery pack formed by densely packing a plurality of battery cells, the battery module and the battery pack can be easily on fire. For example, when an abnormally high temperature occurs in one battery cell and catches fire, heat can easily spread to adjacent battery cells, thereby causing a larger fire. Therefore, although a fire occurs in some battery cells, the fire can spread to the entire area including a battery rack or a power storage device outside the battery module or the battery pack, which increases the risk of injury and can also cause a huge economic loss. Therefore, it is necessary to quickly and accurately extinguish a fire before all battery modules included in the battery rack or the power storage device burn or are damaged.

[0011] So far, various technologies have been proposed to extinguish a fire in a device including a battery module such as a power storage device. However, an effective fire suppression technology has not been developed, and in particular, a fire occurring in a lithium ion battery included in a battery module is not easily extinguished with a general fire extinguishing agent, and in the case of densely packing a plurality of battery modules, it is still a challenge to selectively extinguish a fire only in a battery module in which a fire occurs among the plurality of battery modules. Therefore, there is a need for a method capable of effectively preventing the spread into a large fire by isolating a battery cell in which a high temperature phenomenon has occurred from other battery cells as early as possible. SUMMARY

[0012] TECHNICAL PROBLEM

[0013] The problem that the present application attempts to solve is to provide a battery module capable of effectively extinguishing a fire even when a fire occurs in some battery cells and preventing the spread into a larger fire, and a battery pack including the same.

[0014] However, the tasks that embodiments of the present application attempt to solve are not limited to the above tasks, and can be expanded in various ways within the scope of the technical idea that can be included in the present application.

[0015] TECHNICAL SOLUTION

[0016] A battery module according to an embodiment includes a battery cell assembly formed by stacking a plurality of battery cells, a module frame accommodating the battery cell assembly and including a bottom portion, and a phase change material layer disposed in a lower portion of the battery cell assembly, wherein the phase change material layer is melted and eliminated in a portion corresponding to a battery cell in which a high-temperature phenomenon occurs among the plurality of battery cells, and a bottom portion of the battery cell is opened in the portion in which the phase change material layer is eliminated, so that the battery cell in which the high-temperature phenomenon has occurred is discharged to the outside.

[0017] An injection nozzle in which nitrogen is injected can be formed on an upper surface of the module frame.

[0018] Nitrogen is injected through the injection nozzle, so the battery cell in which the high-temperature phenomenon occurs is pressed downward and discharged.

[0019] The bottom portion can be broken and opened by the battery cell in which the high-temperature phenomenon occurs being pressed downward.

[0020] A lubricant can be applied between the plurality of battery cells.

[0021] The battery module can further include at least one spring that presses each of the plurality of battery cells downward at an upper portion of each of the plurality of battery cells.

[0022] After the battery cell in which the high-temperature phenomenon occurs is discharged, the spring can fill at least a portion of a space in which the battery cell in which the high-temperature phenomenon occurs is placed.

[0023] The bottom portion can include a plurality of opening / closing portions corresponding to the plurality of battery cells, respectively.

[0024] The opening / closing portions can be configured to be opened due to heat or pressure applied by the battery cell in which the high-temperature phenomenon occurs.

[0025] A battery pack according to an embodiment includes the battery module.

[0026] Advantageous Effects

[0027] According to an embodiment of the present application, it is possible to provide a battery module and a battery pack including the same, which can prevent a fire by separating a battery cell in which a high-temperature phenomenon has occurred from other battery cells as early as possible before the fire occurs.

[0028] Effects of the present application are not limited to what has been described above and other effects not mentioned will become clear to those skilled in the art from the description of the scope of the claims. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a perspective view of a battery module according to an embodiment.

[0030] Figure 2 is Figure 1 a battery module.

[0031] Figure 3 shows a cross section taken along line A-A' of Figure 1

[0032] Figure 4 illustrates a state of a cell that has occurred a high temperature phenomenon in Figure 3

[0033] Figure 5 illustrates a state of a cell that has occurred a high temperature phenomenon in a battery module according to another embodiment.

[0034] Figure 6 illustrates a state of a cell that has occurred a high temperature phenomenon in a battery module according to still another embodiment. DETAILED DESCRIPTION

[0035] Hereinafter, various embodiments of the present application are described in detail with reference to the accompanying drawings. The present application can be implemented in various forms and is not limited to the embodiments described herein.

[0036] For the sake of clear explanation of the present application, parts irrelevant to the description are omitted, and the same reference numerals are used for the same or similar components throughout the specification.

[0037] In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for better understanding and convenience of description, and thus the present application is not necessarily limited to what is shown. In the drawings, the thickness of layers, films, panels, regions, and the like is exaggerated for clarity. In addition, in the drawings, the thickness of some layers and regions is exaggerated for better understanding and convenience of description.

[0038] It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. In addition, throughout the specification, the word "on" will be understood to mean positioned on or above, and not necessarily directly on, as long as it is in the general direction of the other element.

[0039] In addition, unless explicitly described to the contrary, the word "comprise" and variations such as "comprises" or "comprising" will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. ​​

[0040] Also, throughout the specification, the phrase "in plan" refers to observing the target portion from the top, and the phrase "in cross section" refers to observing a cross section formed by vertically cutting the target portion from the side.

[0041] Hereinafter, a battery module according to an embodiment will be described with reference to the accompanying drawings. Figures 1 to 4 A battery module according to an embodiment will be described.

[0042] Figure 1 is a perspective view of a battery module according to an embodiment. Figure 2 is Figure 1 is an exploded perspective view of the battery module of Figure 3 shows a cross section of Figure 1 taken along line A-A'. Figure 4 illustrates a state in which a cell in which a high-temperature phenomenon has occurred is discharged in Figure 3

[0043] With reference to Figures 1 to 3 , a battery module 100 according to an embodiment includes a battery cell assembly 120 in which a plurality of battery cells 110 are stacked in one direction, and a module frame 200 in which the battery cell assembly 120 is accommodated.

[0044] First, the battery cell 110 can be a pouch-type battery cell, but is not limited thereto, and various types of battery cells can be applied. The plurality of battery cells 110 are stacked so as to be electrically connected to each other to form the battery cell assembly 120. For example, as shown in Figure 2 , the plurality of battery cells 110 can be stacked in a direction parallel to the y-axis. Accordingly, the electrode lead 111 can protrude in the x-axis direction and the -x-axis direction, respectively. A bus bar frame (not shown) can be provided on either side of the battery cell assembly 120 in the direction in which the electrode lead protrudes. However, this is an exemplary arrangement, and the position of the bus bar frame is not limited thereto, and the bus bar frame can be arranged to cover other surfaces of the battery cell assembly 120. That is, when the position of the bus bar can be electrically connected to the electrode lead 111 according to the protruding direction of the electrode lead 111, the position of the bus bar frame can also be appropriately changed and is not particularly limited.

[0045] The battery cells 110 are stacked in one direction to form the battery cell assembly 120. Specifically, the battery cells 110 can be stacked in the direction while vertically standing with the sides of each of the battery cells 110 facing each other.

[0046] ​The module frame 200 according to the present embodiment can include two side surface portions 210 and 220, an upper surface portion 230, and a bottom portion 240 as a member in which the battery cell assembly 120 is accommodated. In addition, one side (x-axis direction) and the other side (-x-axis direction) of the module frame 200 can be open, and the battery cell assembly 120 can be accommodated through the open one side or the other side. Figure 2 The illustrated module frame 200 can be a single frame in which the two side surface portions 210 and 220, the upper surface portion 230, and the bottom portion 240 are integrated. That is, the module frame 200 can be manufactured by extrusion molding and can have a form in which the two side surface portions 210 and 220, the upper surface portion 230, and the bottom portion 240 are integrally formed. Although not specifically illustrated, as another embodiment of the present application, a module frame in the form in which a U-shaped frame and an upper plate are welded to each other or a reverse U-shaped frame and a lower plate are welded to each other is also possible, and various forms of frames can be applied without particular limitation. When viewed from the stacking direction of the module frame 200 and the battery cells 110, the battery cells 110 can be stacked from one side surface portion 210 to the other side surface portion 220 such that one side of the battery cells 110 is parallel to one side of the side surface portions 210 and 220 of the module frame 200.

[0047] In addition, the battery module 100 according to the present embodiment can further include end plates 300 disposed on one open side and the other open side of the module frame 200, respectively. The end plates 300 can be disposed to cover the battery cell assembly 120 on one open side and the other open side of the module frame 200. The corner portions of each end plate 300 can be joined to the corresponding corner portions of the module frame 200 by welding. The end plates 300 can include a metal material having a predetermined strength and can protect the battery cell assembly 120 and other electrical components from the influence of external impact.

[0048] The battery module 100 may further include a phase change material layer 400 disposed between the battery cell assembly 120 and the bottom portion 240 of the module frame 200. The phase change material layer 400 may include a phase change material (PCM). A phase change material is a material that repeatedly exhibits heat storage and heat dissipation characteristics by absorbing heat when the ambient temperature rises and releasing heat by crystallizing when the ambient temperature falls. Under normal conditions of the battery cell 110, the phase change material absorbs heat from the battery cell 110, thereby achieving a cooling effect. Furthermore, the phase change material included in the phase change material layer 400 may have the characteristic that it melts at high temperatures close to a specific temperature (particularly the ignition temperature of the battery cell 110), thereby eliminating the portion of the battery cell 110 where high temperatures occur. Therefore, paraffin wax, various hydrated salts, polyethylene glycol (PSG), etc., can be used as such a phase change material. Additionally, the phase change material layer 400 may contain only the phase change material, or it may be used by mixing it with various materials to facilitate processing during manufacturing processes, etc., without particular limitations.

[0049] As described above, when high temperatures occur in some of the multiple battery cells 110, the phase change material layer 400 can melt by absorbing the heat generated in the battery cells and be eliminated due to sagging. That is, as... Figure 4 As shown, the portion corresponding to the battery cell 110' that has experienced a high temperature is melted and eliminated, and then the bottom portion 240 of the corresponding portion is opened, thereby allowing the battery cell 110' that has experienced a high temperature to be discharged to the outside. The process of discharging the battery cell 110' that has experienced a high temperature to the outside can be achieved by falling downwards due to gravity or by the pressure of the exhaust gas generated from the battery cell 110' that has experienced a high temperature. In this case, the bottom portion 240 of the phase change material layer 400 can be opened due to the destruction caused by high temperature and high pressure.

[0050] Alternatively, the overheated battery cell 110' can be manually vented before ignition fully occurs. For this purpose, an injection nozzle 500 for injecting nitrogen gas can be included in the upper surface portion 210 of the module frame 200. The injection nozzle 500 is connected to a nitrogen storage container (not shown) separately disposed outside the battery module 100 and opens when a specific temperature is reached to inject nitrogen gas into the battery module 100, thereby increasing the pressure inside the battery module 100. Therefore, the battery cell 110 can be pressurized from above, and in this process, since the phase change material layer 400 below the overheated battery cell 110' is eliminated due to the high temperature and pressure, it can be vented by pushing down only the overheated battery cell 110'. Therefore, the overheated battery cell 110' can be vented before ignition occurs, thereby preventing fire.

[0051] Further, when discharging the battery cell 110' in which the high-temperature phenomenon has occurred, a lubricant can be applied between the battery cells 110 to ensure smooth discharge. Then, the frictional force between the adjacent battery cells 110 is reduced, and an effect of more quickly discharging to the outside when discharging the battery cell 110' in which the high-temperature phenomenon has occurred can be obtained.

[0052] As described above, according to the embodiment, when the high-temperature phenomenon occurs in the battery cell 110' including the phase change material layer 400 at the bottom of the battery cell assembly 120, the phase change material layer 400 is melted and eliminated, thereby causing the battery cell 110' in which the high-temperature phenomenon has occurred to be quickly discharged to the outside (the bottom), so that the battery cell 110' in which the high-temperature phenomenon has occurred can be isolated from the other battery cells 110 and the spread of fire and the occurrence of fire can be prevented, thereby improving the safety of the battery module 100. Further, in the present embodiment, a case in which the battery cell assembly 120 is accommodated in the module frame 200 and is discharged to the outside of the module frame 200 is described as an example, but is not limited thereto, and any structure in which a plurality of battery cells 110 are disposed is applicable.

[0053] Hereinafter, a battery module according to another embodiment will be further described with reference to Figure 5 A battery module according to another embodiment is further described.

[0054] Figure 5 A state of discharging a cell in which a high-temperature phenomenon has occurred in a battery module according to another embodiment is exemplified.

[0055] Referring to Figure 5 In the battery module 100 according to another embodiment, at least one spring 410 that presses down the plurality of battery cells 110 can be provided in the upper portion of each of the plurality of battery cells 110. For example, the spring 410 can be provided in plurality along the length direction (x-axis direction) of the battery cell 110. Due to the elasticity of the spring 410, the battery cell 110 can be pressed down. In this case, as shown in FIG. 6, when the high-temperature phenomenon occurs in the battery cell 110', the battery cell 110' in which the high-temperature phenomenon has occurred can be pressed and more quickly discharged downward (because it is pressed by the spring 410). That is, the battery cell 110' in which the high-temperature phenomenon has occurred can be effectively pressed and discharged without injecting nitrogen through the nozzle 500, or together with the injection of nitrogen. Figure 5

[0056] In addition, as shown in FIG. 7, the spring 410 can be provided in the upper portion of each of the plurality of battery cells 110. In this case, as shown in FIG. 7, when the high-temperature phenomenon occurs in the battery cell 110', the battery cell 110' in which the high-temperature phenomenon has occurred can be pressed and more quickly discharged downward (because it is pressed by the spring 410). That is, the battery cell 110' in which the high-temperature phenomenon has occurred can be effectively pressed and discharged without injecting nitrogen through the nozzle 500, or together with the injection of nitrogen. Figure 5 ​As illustrated, after the battery cell 110' in which the high-temperature phenomenon has occurred is discharged, the spring 410, which has lost its elasticity, is placed in the empty space in which the battery cell 110' in which the high-temperature phenomenon has occurred is discharged, and thus the spring 410 can fill at least a portion of the space in which the battery cell 110' in which the high-temperature phenomenon has occurred is placed. This allows the remaining battery cells 110 to maintain the stacked structure.

[0057] Hereinafter, further referring to Figure 6 A battery module according to still another embodiment of the present application will be described.

[0058] Figure 6 A state in which a cell in which a high-temperature phenomenon has occurred is discharged in a battery module according to still another embodiment is exemplified.

[0059] Referring to Figure 6 A battery module 100 according to still another embodiment of the present application includes a plurality of opening / closing portions 241 corresponding to a plurality of battery cells 110 in the bottom portion 240, respectively. The opening / closing portions 241 can be configured to be closed in a normal state, but to be opened only when an abnormal situation occurs and a certain level of heat or pressure is generated and applied. This configuration can be implemented in various ways. For example, a configuration in which a portion supporting the opening / closing portions 241 is fixed by a phase change material layer 400 in a normal state and is eliminated together when the phase change material layer 400 is eliminated and the opening / closing portions 241 are opened is also possible. Alternatively, a joint portion between the opening / closing portions 241 can be configured to have a lower melting point or a smaller thickness than other portions so that the joint portion is melted first at a high temperature. By providing the opening / closing portions 241 separately provided in this way, the battery cell 110' in which a high-temperature phenomenon has occurred can be more quickly discharged to the outside.

[0060] In the present embodiment, terms indicating directions such as front, rear, left, right, up, and down are used, but these terms are used only for better understanding and convenience of description, and can vary depending on the position of the target object or the position of the observer.

[0061] One or more battery modules according to the above-described embodiments can be installed together with various control and protection systems such as a battery management system (BMS), a battery disconnect unit (BDU), and a cooling system to form a battery pack.

[0062] The battery module or the battery pack can be applied to various devices. Specifically, it can be applied to a vehicle such as an electric bicycle, an electric vehicle, a hybrid vehicle, etc. or an energy storage system (ESS), but is not limited thereto, and can be applied to various devices capable of using a secondary battery.

[0063] While the application has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the application is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements.

[0064] [Explanation of symbols]

[0065] 100: battery module

[0066] 110: battery cell

[0067] 120: battery cell assembly

[0068] 200: module frame

[0069] 240: bottom portion

[0070] 241: opening / closing portion

[0071] 300: end plate

[0072] 400: phase change material layer

[0073] 410: spring

[0074] 500: injection nozzle

Claims

1. A battery module, the battery module comprising: A battery cell assembly formed by stacking multiple battery cells; Module frame, the module frame accommodating the battery cell assembly and including a bottom portion; and A phase change material layer is disposed in the lower portion of the battery cell assembly. The phase change material layer is melted and eliminated in the portion of the battery cell corresponding to the portion where high temperatures occur in the plurality of battery cells, and The bottom portion of the battery cell is opened in the part where the phase change material layer is eliminated, so that the battery cell in which the high temperature phenomenon occurs is discharged to the outside.

2. The battery module according to claim 1, wherein, An injection nozzle for injecting nitrogen gas is formed on the upper surface of the module frame.

3. The battery module according to claim 2, wherein, Nitrogen gas is injected through the injection nozzle, and the battery cell where the high temperature phenomenon occurs is pressed down and discharged.

4. The battery module according to claim 3, wherein, The bottom portion cracked and opened due to the downward pressure of the battery cell caused by the high temperature phenomenon.

5. The battery module according to claim 1, wherein, Lubricant is applied between the plurality of battery cells.

6. The battery module according to claim 1, the battery module further comprising at least one spring, the at least one spring pressing down on each of the plurality of battery cells at the upper portion of each of the plurality of battery cells.

7. The battery module according to claim 6, wherein, After the battery cell that experienced the high temperature phenomenon is discharged, the spring fills at least a portion of the space where the battery cell that experienced the high temperature phenomenon was placed.

8. The battery module according to claim 1, wherein, The bottom portion includes multiple open / closed sections, each corresponding to one of the multiple battery cells.

9. The battery module according to claim 8, wherein, The open / close section is configured to open due to heat or pressure applied by the battery cell when the high temperature phenomenon occurs.

10. A battery pack comprising the battery module according to claim 1.

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