Battery pack and device including the same

Abstract

A battery pack according to an embodiment of the present invention comprises: a plurality of battery modules; and a case accommodating the plurality of battery modules, in which the case includes a plurality of openable / closable valves, and the plurality of valves are sequentially opened and closed according to internal pressure.

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0002] This application claims the priority benefit of Korean Patent Application No. 10 - 2023 - 0001881, filed with the Korean Intellectual Property Office on January 5, 2023, the entire contents of which are incorporated herein by reference.

[0003] The present disclosure relates to a battery pack and a device including the battery pack, and more particularly, to a battery pack having improved safety and a device including the battery pack. Background Art

[0004] In modern society, with the daily use of mobile devices such as mobile phones, laptop computers, cameras, or digital cameras, technologies related to such mobile devices are being actively developed. In addition, secondary batteries that can be charged and discharged may be a solution to air pollution caused by conventional gasoline vehicles using fossil fuels, and the secondary batteries are used as power sources for electric vehicles (EVs), hybrid electric vehicles (HEVs), plug - in hybrid electric vehicles (P - HEVs), etc. Therefore, the demand for the development of secondary batteries is increasing day by day.

[0005] Currently commercialized secondary batteries may include nickel - cadmium batteries, nickel - metal hydride batteries, nickel - zinc batteries, and lithium secondary batteries. Among these batteries, lithium secondary batteries may receive much attention because, compared with nickel - based secondary batteries, lithium secondary batteries have almost no memory effect, allow free charge and discharge, have an extremely low self - discharge rate, and have a high energy density.

[0006] The lithium secondary battery may mainly use 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 may include an electrode assembly in which a positive electrode plate and a negative electrode plate coated with the positive electrode active material and the negative electrode active material, respectively, are disposed while a separator is interposed therebetween, and a casing (that is, a battery case) that seals and houses the electrode assembly together with an electrolyte.

[0007] Generally, based on the type of the casing, lithium secondary batteries can be classified into can - type secondary batteries in which the electrode assembly is embedded in a metal can and pouch - type secondary batteries in which the electrode assembly is embedded in a pouch of an aluminum laminate.

[0008] A secondary battery used in a small device may have two or three battery cells disposed therein. However, a secondary battery used in a medium to large device such as an automobile may use a battery module in which a plurality of battery cells are electrically connected to each other. Such a battery module in which a plurality of battery cells are connected in series or in parallel with each other to form a battery cell assembly may have improved capacity and output. In addition, one or more battery modules may be installed in a device together with various control and protection systems such as a battery management system (BMS) and a cooling system to form a battery pack.

[0009] When forming a battery pack by connecting a plurality of battery cells in series / parallel with each other, a commonly used method is to first form a battery module including at least one battery cell, and then form a battery pack by adding another component using at least one battery module. The number of battery modules included in the battery pack or the number of battery cells included in the battery module may be set in various ways based on the required output voltage or charge / discharge capacity.

[0010] In particular, due to the development of high-capacity batteries, the safety of secondary batteries (especially their thermal propagation characteristics) has been recognized as important. As the cell capacity increases, the thermal propagation safety may decrease, which requires improvement. Various techniques are being tried to prevent such thermal propagation. When a problem such as a thermal event occurs, a conventional battery pack with a low energy density may prevent the leakage of flames to the outside due to its low energy and sufficient space. However, recently, a battery pack using high-capacity batteries may have difficulty preventing or controlling thermal propagation due to its higher energy density. Summary of the Invention

[0011] Technical Problem

[0012] The present disclosure attempts to provide a battery pack with higher safety and a device including the battery pack by preventing thermal propagation of the battery pack and preventing explosion of the battery pack or leakage of external flames even when using high-capacity batteries.

[0013] However, the problems to be solved by the embodiments of the present disclosure are not limited to the above problems, and various extensions may be made within the spirit of the present disclosure included in the embodiments.

[0014] Technical Solution

[0015] According to one embodiment, a battery pack includes: a plurality of battery modules; and a housing that houses the plurality of battery modules, wherein the housing has a plurality of valves that can be opened and closed, and the plurality of valves are opened and closed in sequence based on the internal pressure of the housing.

[0016] The plurality of valves may include a first valve to an nth valve, and the opening pressure of each of the plurality of valves may be greater than or equal to the pressure of external oxygen flowing into the housing and less than or equal to the pressure at which the housing is damaged.

[0017] In a state where the first valve to the (n - 1)th valve are open, the nth valve may open as the internal pressure of the housing increases.

[0018] As the internal pressure of the housing decreases, the nth valve to the first valve may be closed in sequence.

[0019] Any one of the plurality of valves may include: a valve body portion including a first flange portion provided outside the housing, a second flange portion provided inside the housing, and a connecting portion connecting the first flange portion and the second flange portion; and an elastic portion formed to surround the connecting portion at a position between the second flange portion and the housing.

[0020] When the internal pressure of the housing increases, the elastic portion may be compressed by pressing the second flange portion to open the valve.

[0021] Each of the plurality of valves may have a different opening pressure by making at least one of the size of the valve body portion and the elastic force of the elastic portion different.

[0022] Any one of the plurality of valves may include: a valve body portion including a first flange portion provided outside the housing, a second flange portion provided inside the housing, and a connecting portion connecting the first flange portion and the second flange portion; a support portion provided between the first flange portion and the housing; and a sensor portion provided in one surface of the support portion facing the inside of the housing.

[0023] The second flange portion may further include a gas communication hole that forms an internal gas discharge passage in a state where the valve is open.

[0024] The sensor portion may include: a sensing hole recessed in one surface of the support portion; a sensing line provided in the sensing hole; and one or more sensors in phased contact with the sensing line.

[0025] According to another embodiment, a device includes at least one of the above battery packs.

[0026] Advantageous Effects

[0027] According to an embodiment of the present disclosure, even when using a high-capacity battery, a battery pack with higher safety and a device including the battery pack can be provided by preventing heat propagation of the battery pack and preventing explosion of the battery pack or leakage of external flames.

[0028] The effects of the present disclosure are not limited to the above effects, and those skilled in the art can clearly understand other effects not mentioned from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is an exploded perspective view of a battery module included in a battery pack according to an embodiment of the present disclosure.

[0030] Figure 2 is a view showing a battery pack according to an embodiment of the present disclosure.

[0031] Figure 3 is a graph showing the opening and closing phases of a valve based on pressure when a thermal event occurs in a battery pack of Figure 2 thereby increasing the internal pressure of the battery pack.

[0032] Figure 4 are views each schematically showing Figure 2 the structure and the opening and closing process of a valve in a battery pack of

[0033] Figure 5 are views each schematically showing the structure and the opening and closing process of a valve in a battery pack according to another embodiment of the present disclosure.

[0034] Figure 6 is Figure 5 an enlarged view of part VI in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings so that those skilled in the art to which the present disclosure pertains can easily practice the present disclosure. The present disclosure can be implemented in various different forms and is not limited to the embodiments provided here.

[0036] To clearly describe the present disclosure, parts irrelevant to the description are omitted, and throughout the specification, the same or similar components are denoted by the same reference numerals.

[0037] In addition, for ease of explanation, the dimensions and thicknesses of each component shown in the drawings are arbitrarily shown, and thus, the present disclosure does not necessarily have to be limited to what is shown in the drawings. To clearly represent several layers and regions, the thicknesses are exaggerated in the drawings. In addition, for ease of explanation, the thicknesses of some layers and regions are exaggerated in the drawings.

[0038] In addition, when an element such as a layer, film, region, or substrate is referred to as being "on" or "above" another element, the element can be "directly" on the other element, or a third element can be interposed therebetween. Conversely, when an element is referred to as being "directly on another element", no third element is interposed therebetween. In addition, when an element is referred to as being "on" or "above" a reference element, the element can be disposed on or below the reference element, and not necessarily in the opposite direction of gravity "on" or "above" the reference element.

[0039] In addition, throughout the specification, unless otherwise described, "including" any component will be understood to implicitly include other elements rather than exclude other elements.

[0040] In addition, throughout the specification, the expression "on a plane" can represent the case of observing an object from the top, and the expression "in a cross-section" can represent the case of observing a cross-section of an object taken along a vertical direction from its side.

[0041] Hereinafter, reference will be made to Figures 1 to 3 describe the battery pack of the present disclosure.

[0042] Figure 1 is an exploded perspective view of a battery module included in a battery pack according to an embodiment of the present disclosure, Figure 2 is a view showing a battery pack according to an embodiment of the present disclosure, and Figure 3 is a view showing when Figure 2 a thermal event occurs in the battery pack, increasing the internal pressure of the battery pack, a graph showing the pressure-based opening and closing phases of the valve.

[0043] Refer to Figure 1 , the battery module 100 included in the battery pack according to an embodiment of the present disclosure may include: a battery cell assembly 400 including one or more battery cells; a module frame 210 storing the battery cell assembly 400; and end plates 300 disposed at each of two end portions of the battery cell assembly 400 in the length direction and connected to the openings of the module frame 210 in parallel.

[0044] The battery cell assembly 400 can be a secondary battery assembly including a plurality of battery cells 112. The battery cell assembly 400 can include a plurality of battery cells 112, and each battery cell can include an electrode lead 114. The battery cell 112 can be a pouch-type battery cell having a plate shape, and is not limited thereto. The electrode lead 114 can be a positive electrode lead or a negative electrode lead. Here, the end portion of the electrode lead 114 of each battery cell 112 can be bent in one direction, and thus can contact the end portion of the electrode lead of another adjacent battery cell 112. The two electrode leads 114 in contact with each other can be fixed to each other by welding or the like, so that the battery cells 112 in the battery cell assembly 400 are electrically connected to each other.

[0045] In addition, the bus bar frame 500 stored in the module frame 210 can be provided together with the battery cell assembly 400. The bus bar frame 500 can include: an upper frame 510 provided on the top of the battery cell assembly 400; a front frame 520 provided on the front surface of the battery cell assembly 400; and a rear frame 530 provided on the rear surface of the battery cell assembly 400 and connected to the bus bar 540 including the electrode leads 114 of the battery cells included in the battery cell assembly 400, and the bus bar 540 can be mounted on each of the front frame 520 and the rear frame 530.

[0046] A plurality of battery cells 112 can be vertically stacked so that the electrode leads 114 are aligned in one direction to form the battery cell assembly 400. The battery cell assembly 400 can be stored in the module frame 210 having at least one opening opened in the length direction of the battery cell assembly 400. Here, the electrode leads 114 can be led out of the module frame 210 through the opening, and the led-out electrode leads 114 can be coupled to each of the front frame 520 and the rear frame 530 of the bus bar frame 500 to be electrically connected to the bus bar 540 mounted thereon. Here, the bus bar frame 500 can be made of an insulating material (such as a non-conductive synthetic resin), and the bus bar 540 can be made of a conductive metal material.

[0047] The battery module 100 can include a flexible printed circuit board (FPCB, not shown) that extends along the length direction of the module frame 210 from the top of the battery cell assembly 400 and is mounted thereon to detect the battery cells 112. In addition, the battery module 100 can include various electrical components, and can include, for example, an internal circuit board (ICB) and a battery management system (BMS). Electrical components such as the ICB and the BMS board can be electrically connected to the plurality of battery cells 112.

[0048] The battery module 100 may further include a thermal conductive resin layer 700 disposed between the lower surface of the battery cell assembly 400 and the module frame 210. The thermal conductive resin layer 700 may be formed of an injected thermal conductive resin and is used to transfer heat generated in the battery cell assembly 400 to the bottom of the battery module 100 and to fix the battery cell assembly 400 in the battery module 100.

[0049] Meanwhile, the radiator 800 may be disposed on the side surface of the battery cell assembly 400 and may be stored in the module frame 210 together with the battery cell assembly 400, and there is no particular limitation.

[0050] In the above, the specification describes the configuration of the battery module 100, but the battery module 100 is not limited to this form or configuration, and in some cases may have different forms or configurations.

[0051] Next, reference will be made to Figures 2 to 4 Describe the battery pack 10 according to an embodiment of the present disclosure.

[0052] The battery pack 10 may include one or more battery modules 100, a housing 11 that houses the battery modules, and a plurality of valves 20 formed in the housing 11 and capable of opening and closing.

[0053] The housing 11 may include a battery pack frame (not shown) on which one or more battery modules 100 are disposed, and a top plate coupled to the battery pack frame to thereby seal the battery module 100. The housing 11 is not limited to this configuration and may appropriately adopt any structure capable of protecting the battery module 100 from external influences.

[0054] The plurality of valves 20 formed in the housing 11 may be valves capable of opening and closing, and may include a first valve to an nth valve. In this embodiment, the plurality of valves 20 are shown as including a first valve 21, a second valve 22, a third valve 23, and a fourth valve 24, but are not limited thereto, and may include an appropriate number of valves by considering the capacity and number of the battery modules 100 included in the battery pack 10 and the opening pressure of each valve 20.

[0055] Each of the plurality of valves 20 may open and close based on a set opening and closing pressure. In particular, the opening pressure may increase sequentially from the first valve to the nth valve. Here, the opening pressure of each of the plurality of valves 20 may be set to be greater than the pressure at which oxygen flows into the housing 11 and less than the pressure at which the housing 11 is damaged or explodes.

[0056] Reference will be made to Figure 3 Describe its details in more detail.

[0057] That is, as Figure 3As shown, a thermal event (or thermal propagation) may occur in the battery pack 10 to increase its internal pressure. In this case, the first valve 21 may open to reduce the gas to the outside, thereby suppressing the increase in internal pressure. However, when gas continuously appears, even when the first valve 21 is open, the internal pressure may continuously increase. Therefore, when the internal pressure reaches the opening pressure of the second valve 22, the second valve 22 may also discharge to release the internal gas.

[0058] In this way, the valve 20 may open in sequence, and when the x-th valve (for example, the third valve 23) opens, the generation of internal gas may stop. In this case, when the internal pressure decreases, the third valve 23 may close, and when the internal pressure continuously decreases to reach the closing pressure of the second valve 22, the second valve 22 may close. If the valve does not close here and remains open, the internal pressure may continuously decrease and eventually decrease to reach the external oxygen inflow pressure. Therefore, oxygen may flow in from the outside, and thus combustion in the battery pack 10 may be promoted, resulting in the occurrence of a flame and the external propagation of the flame, which is not preferred. However, in the present disclosure, even when a pressure drop occurs while the valve is open, the valve 20 may open in sequence and then close in sequence again, thereby preventing the pressure from dropping to the oxygen inflow pressure, thereby ensuring improved safety by suppressing combustion in the battery pack 10.

[0059] Meanwhile, even when the x-th valve opens, when the internal pressure continues to rise, the n-th valve (or the fourth valve 24 shown in this figure) may open. The opening pressure of the corresponding valve may be set to have a pressure close to the pressure at which the housing 11 can be damaged. Therefore, before the internal pressure reaches the housing failure pressure, the n-th valve may open to reduce the internal pressure by discharging the gas to the outside. In this way, it is possible to prevent the internal pressure of the battery pack 10 from reaching the housing failure pressure, thereby preventing the housing from being damaged (that is, preventing the battery pack 10 from exploding due to its internal pressure).

[0060] After the n-th valve or the fourth valve 24 in this embodiment closes, the internal pressure may drop, and during the process of the internal pressure dropping, the previous valves may close in sequence, thereby preventing a rapid drop in the internal pressure. In addition, during this process, the internal combustion and thermal event of the battery pack 10 may end, thereby ending the thermal event state without damaging the housing 11 and the external propagation of the internal combustion.

[0061] In this way, the thermal event state can be stably terminated, so that the thermal event state can be terminated without the occurrence of damage or explosion of the housing 11 of the battery pack 10, thereby preventing external heat propagation and ensuring the safety of the improved battery pack 10. In addition, in this embodiment, the plurality of valves 20 can be opened sequentially based on the pressure increase and closed sequentially based on the pressure decrease, rather than being opened jointly when the internal pressure increases, or being unable to be closed after being opened, thereby preventing an explosion caused by the inflow of external oxygen. That is, an explosion may occur due to the rapid inflow of external oxygen caused by the rapid internal pressure drop when the valves are opened jointly, or due to the valves being unable to be closed after being opened when the plurality of valves remain open regardless of the pressure drop. According to an embodiment of the present disclosure, the internal pressure can be maintained within a certain range by opening and closing the valves sequentially, thereby preventing an explosion.

[0062] Hereinafter, the description will refer to Figures 4 to 6 specific examples of valves that can be used in the present disclosure.

[0063] Figure 4 each schematically shows Figure 2 the structure and the opening and closing process of the valve in the battery pack; Figure 5 each schematically shows the structure and the opening and closing process of the valve in the battery pack according to another embodiment of the present disclosure; and Figure 6 is Figure 5 an enlarged view of part VI in

[0064] As Figure 4 shown, the valve 20 according to an embodiment of the present disclosure may include: a valve body portion 30 including a first flange portion 31 provided outside the housing 11; a second flange portion 32 provided in the housing 11; and a connecting portion 33 connecting the first flange portion 31 and the second flange portion 32 to each other. A gasket 60 may be provided in the first flange portion 31 along the edge of the first flange portion 31, and a support portion 40 may be provided between the gasket 60 and the housing 11 and contact the gasket 60 when no internal pressure is applied. In addition, an elastic portion 50 may be provided between the inner surface of the housing 11 and the second flange portion 32, surrounding the connecting portion 33, and including a spring or the like.

[0065] In this structure, the valve 20 can be opened by compressing the elastic portion 50 when internal pressure is applied thereto. That is, Figure 4(a) (i.e., the left figure) shows the state where the valve 20 is closed before internal pressure is applied thereto. In this state, when internal pressure is applied to the second flange portion 32, the elastic portion 50 can be compressed to push the valve body portion 30 outward. As a result, the gasket 60 and the support portion 40 can fall from the valve body portion 30, and the valve 20 can be opened, as shown in (b) (i.e., the right figure). In this state, when the internal pressure decreases to reach the closing pressure of the valve 20, the compression of the elastic portion 50 can be released, and the valve 20 can be closed to return to the same state as shown in (a). Therefore, the magnitude of the internal pressure for opening and closing the valve 20 can be determined by the magnitude of the elastic force of the elastic portion 50 and / or the size of the valve 20.

[0066] Meanwhile, as Figure 5 shown, the valve 20 can be controlled to open and close by including a sensor portion 70 instead of the elastic portion 50. That is, the valve 20 according to another embodiment of the present disclosure can include a sensor portion 70 disposed in the support portion 40 (that is, disposed in one surface of the valve 20 communicating with the housing 11). The valve 20 can be opened and closed by the sensor portion 70 such that the valve body portion 30 moves forward and backward outward from the housing 11. That is, Figure 5 (a) shows the state where the valve 20 is closed when the valve body portion 30 is disposed toward the inside of the housing 11 and the gasket 60 and the support portion 40 are in contact with each other, while (b) shows the state where the valve 20 is closed when the valve body portion 30 moves outward from the housing 11. Here, as shown in (b), the valve 20 of this embodiment can further include a gas communication hole 34 in the second flange portion 32 so as to form a gas passage especially when the valve is opened.

[0067] Referring to Figure 6 , the sensor portion 70 that controls the opening and closing of the valve 20 in this way can include a first sensor 72 and a second sensor 73 formed in the inner surface of the support portion 40 and a sensing line 71 disposed in the sensing hole 41. The sensing line 71 can be recessed inward from the sensing hole 41 due to internal pressure, and thus it can be determined whether the internal pressure has increased based on whether the sensing line 71 is in contact with the sensor.

[0068] Specifically, when in the normal state, the sensing line 71 can be set at the position 71a in the figure and can be not in contact with the first sensor 72 and the second sensor 73, and herein, the valve 20 can remain closed. When the sensing line 71 is indented inward due to the internal pressure and thus reaches the position 71b in the figure, the sensing line 71 can be in contact with both the first sensor 72 and the second sensor 73, and the valve 20 can be controlled to remain open herein. During the process of the internal pressure decreasing and the sensing line 71 thus returning to the position 71a, when the sensing line 71 first releases its contact with the second sensor 73 and also releases its contact with the first sensor 72, the valve 20 can be controlled to close again. Thus, when controlling the opening and closing of the valve 20 by using the sensor part 70, the opening and closing pressures of the valve 20 can be set differently based on the settings of the first sensor 72 and the second sensor 73.

[0069] As described above, the battery pack according to the embodiment of the present disclosure can ensure improved safety by including a plurality of valves that can be opened and closed in sequence, wherein even if a thermal event occurs in the battery pack and the internal pressure rises, the plurality of valves can be opened and closed, thereby preventing the destruction of the housing and the inflow of external oxygen, and thus preventing the explosion of the battery pack.

[0070] The above battery pack can be applied to various devices. Such devices can be applied to transportation tools such as electric bicycles, electric vehicles, and hybrid vehicles. However, the present disclosure is not limited thereto, and can be applied to various devices that can use battery modules and battery packs including battery modules, which also fall within the scope of the present disclosure.

[0071] Although the embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto, and several modifications and changes made by those skilled in the art using the basic concepts of the present disclosure defined in the claims are all included in the scope of the present disclosure.

[0072] [Description of reference numerals]

[0073] 100: Battery module

[0074] 10: Battery pack

[0075] 20: Valve

[0076] 30: Valve body part

[0077] 40: Support part

[0078] 50: Elastic part

[0079] 60: Gasket

[0080] 70: Sensor part

Claims

1. A battery pack, the battery pack comprising: a plurality of battery modules; and a housing that houses the plurality of battery modules, wherein the housing has a plurality of valves that can be opened and closed, and the plurality of valves are opened and closed in sequence based on the internal pressure.

2. The battery pack according to claim 1, wherein the plurality of valves include a first valve to an nth valve, and the opening pressure of the plurality of valves is greater than or equal to the pressure at which external oxygen flows into the housing and less than or equal to the pressure at which the housing is damaged.

3. The battery pack according to claim 2, wherein in a state where the first valve to the (n - 1)th valve are opened, the nth valve is opened as the internal pressure of the housing increases.

4. The battery pack according to claim 3, wherein as the internal pressure of the housing decreases, the nth valve to the first valve are closed in sequence.

5. The battery pack according to claim 1, wherein any one of the plurality of valves includes: a valve body portion that includes a first flange portion provided outside the housing, a second flange portion provided inside the housing, and a connection portion that connects the first flange portion and the second flange portion; and an elastic portion that is formed to surround the connection portion at a position between the second flange portion and the housing.

6. The battery pack according to claim 5, wherein when the internal pressure of the housing increases, the elastic portion is compressed by pressing the second flange portion, thereby opening the valve.

7. The battery pack according to claim 5, wherein each of the plurality of valves has a different opening pressure by making at least one of the size of the valve body portion and the elastic force of the elastic portion different.

8. The battery pack according to claim 1, wherein any one of the plurality of valves includes: a valve body portion that includes a first flange portion provided outside the housing, a second flange portion provided inside the housing, and a connection portion that connects the first flange portion and the second flange portion; a support portion provided between the first flange portion and the housing; and a sensor portion provided in one surface of the support portion facing the inside of the housing.

9. The battery pack according to claim 8, wherein the second flange portion further includes a gas communication hole that forms an internal gas discharge passage in a state where the valve is opened.

10. The battery pack according to claim 9, wherein the sensor portion includes: a sensing hole that is recessed in one surface of the support portion; a sensing wire provided in the sensing hole; and one or more sensors that are in contact with the sensing wire at intervals.

11. An apparatus including at least one battery pack according to claim 1.

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