Battery packs and devices containing them

Abstract

A battery pack according to an embodiment of the present invention includes a plurality of battery modules and a housing that accommodates the plurality of battery modules. The housing includes a plurality of openable and closable valves that are sequentially opened and closed according to internal pressure.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0001881, filed January 5, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a battery pack and a device including the same, and more particularly to a battery pack with improved safety and a device including the same. [Background technology]

[0003] In modern society, the use of portable devices such as mobile phones, laptops, video cameras, and digital cameras has become commonplace, and technological development in fields related to these mobile devices is accelerating. Furthermore, rechargeable secondary batteries are being used as power sources for electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (P-HEVs), and other vehicles as a way to address air pollution caused by conventional gasoline-powered vehicles that use fossil fuels, and this has led to an increased need for the development of secondary batteries.

[0004] Currently, commercially available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Of these, lithium secondary batteries are attracting attention due to their advantages over nickel-based secondary batteries, such as almost no memory effect, freedom in charging and discharging, extremely low self-discharge rate, and high energy density.

[0005] Such lithium secondary batteries mainly use lithium-based oxides and carbon materials as the positive and negative electrode active materials, respectively, and include an electrode assembly in which a positive electrode plate and a negative electrode plate coated with the positive and negative electrode active materials are disposed with a separator between them, and an exterior material, i.e., a battery case, that hermetically houses the electrode assembly together with an electrolyte.

[0006] Generally, lithium secondary batteries can be classified into can-type secondary batteries, in which an electrode assembly is housed in a metal can, and pouch-type secondary batteries, in which an electrode assembly is housed in a pouch made of an aluminum laminate sheet, depending on the shape of the exterior material.

[0007] Secondary batteries used in small devices are configured with two to three battery cells, while secondary batteries used in medium- to large-sized devices such as automobiles are configured as battery modules, in which a large number of battery cells are electrically connected. Such battery modules improve capacity and output by connecting multiple battery cells in series or parallel to form cell assemblies. In addition, one or more battery modules can be installed together with various control and protection systems such as a Battery Management System (BMS) and a cooling system to form a battery pack.

[0008] When a battery pack is constructed by connecting a plurality of battery cells in series or parallel, a battery module consisting of at least one battery cell is generally constructed first, and other components are then added to the battery pack using the at least one battery module. The number of battery modules included in the battery pack or the number of battery cells included in a battery module can be set in various ways depending on the required output voltage or charge / discharge capacity.

[0009] In recent years, with the development of large-capacity cells, the safety of secondary batteries, especially their thermal propagation characteristics, has become increasingly important. As the cell capacity increases, the safety of thermal propagation decreases, so this needs to be improved. Various technologies are being attempted to prevent such thermal propagation. In conventional battery packs with low energy density, when a problem such as a thermal event occurs, the low energy and ample space prevent the flame from spreading to the outside. However, in the case of battery packs using recent high-capacity cells, the high energy density makes it difficult to prevent and control thermal propagation. Summary of the Invention [Problem to be solved by the invention]

[0010] The problem to be solved by the present invention is to provide a battery pack and a device including the same, which have enhanced safety by preventing heat propagation in the battery pack and preventing explosion of the battery pack and external fire leakage even when high-capacity cells are used.

[0011] However, the problems to be solved by the embodiments of the present invention are not limited to the above-mentioned problems, and can be variously expanded within the scope of the technical ideas included in the present invention. [Means for solving the problem]

[0012] A battery pack according to one embodiment of the present invention includes a plurality of battery modules and a housing that accommodates the plurality of battery modules, the housing including a plurality of openable and closable valves that open and close sequentially in response to an internal pressure.

[0013] The plurality of valves may include first to n-th valves, and the opening pressure of the plurality of valves may be equal to or higher than a pressure at which external oxygen flows into the housing and equal to or lower than a pressure at which the housing is destroyed.

[0014] The nth valve can open as the pressure inside the housing increases while the 1st to (n-1th)th valves are open.

[0015] As the pressure inside the housing decreases, the nth valve to the first valve can be closed in order.

[0016] Any of the plurality of valves may include a valve body including a first flange portion located outside the housing, a second flange portion located inside the housing, and a connecting portion connecting the first flange portion and the second flange portion, and an elastic portion formed to enclose the connecting portion at a position between the second flange portion and the housing.

[0017] When pressure inside the housing increases, pressure is applied to the second flange portion, compressing the elastic portion and thereby opening the valve.

[0018] The plurality of valves can have different opening pressures by varying at least one of the size of the valve body and the elastic force of the elastic portion.

[0019] Any of the plurality of valves may include a valve body including a first flange portion located outside the housing, a second flange portion located inside the housing, and a connecting portion connecting the first flange portion and the second flange portion, a support portion disposed between the first flange portion and the housing, and a sensor portion formed on one surface of the support portion facing the interior of the housing.

[0020] The second flange portion may further include a gas communication hole that forms a discharge passage for the internal gas when the valve is open.

[0021] The sensor unit may include a sensing hole recessed in one surface of the support, a sensing wire disposed in the sensing hole, and at least one sensor configured to come into step-like contact with the sensing wire.

[0022] A device according to another embodiment of the present invention may include the at least one battery pack. [Effects of the Invention]

[0023] According to an embodiment of the present invention, it is possible to provide a battery pack and a device including the same that have enhanced safety by preventing heat propagation in the battery pack and preventing explosion of the battery pack or external fire even when high-capacity cells are used.

[0024] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is an exploded perspective view of a battery module included in a battery pack according to an embodiment of the present invention; [Figure 2] 1 is a diagram showing a battery pack according to an embodiment of the present invention. [Figure 3] 3 is a graph showing the opening and closing stages of a valve according to pressure when thermal runaway occurs in the battery pack of FIG. 2 and the internal pressure increases. [Figure 4] 3 is a diagram schematically illustrating the structure of a valve in the battery pack of FIG. 2 and the opening and closing process. [Figure 5] 4 is a diagram illustrating the structure and opening / closing process of a valve in a battery pack according to another embodiment of the present invention; [Figure 6] 6 is an enlarged view of VI in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily implement various embodiments of the present invention. The present invention can be embodied in several different forms and is not limited to the examples described herein.

[0027] In order to clearly describe the present invention, parts that are not relevant to the description will be omitted and the same reference numerals will be used throughout the specification to refer to the same or similar components.

[0028] In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for the convenience of explanation, and the present invention is not necessarily limited to those shown in the drawings. In the drawings, thicknesses are exaggerated to clearly show multiple layers and regions. In the drawings, thicknesses of some layers and regions are exaggerated for the convenience of explanation.

[0029] Furthermore, when a layer, film, region, plate, or other part is said to be "on" or "above" another part, this includes not only the case where it is "directly above" that other part, but also the case where there is another part in between. Conversely, when a part is said to be "directly above" another part, it means that there is no other part in the middle. Furthermore, being "on" or "above" a reference part means being located above or below the reference part, and does not necessarily mean being "above" or "above" facing the opposite direction of gravity.

[0030] Furthermore, throughout the specification, when a part "comprises" a certain element, it does not mean that it excludes other elements, but that it may further include other elements, unless otherwise specified.

[0031] Also, throughout the specification, "on a plane" means when the target part is viewed from above, and "on a cross section" means when the target part is cut vertically and viewed from the side.

[0032] The battery pack of the present invention will be described below with reference to FIGS.

[0033] FIG. 1 is an exploded perspective view of a battery module included in a battery pack according to an embodiment of the present invention, FIG. 2 is a view showing a battery pack according to an embodiment of the present invention, and FIG. 3 is a graph showing the opening and closing stages of a valve according to pressure when thermal runaway occurs in the battery pack of FIG. 2 and the internal pressure increases.

[0034] Referring to FIG. 1, a battery module 100 included in a battery pack according to an embodiment of the present invention includes a battery cell assembly 400 including one or more battery cells, a module frame 210 that houses the battery cell assembly 400, and end plates 300 that are located at both ends of the battery cell assembly 400 in the longitudinal direction and are coupled to openings in the module frame 210.

[0035] The battery cell assembly 400 is a secondary battery assembly including a plurality of battery cells 112. The battery cell assembly 400 may include a plurality of battery cells 112, each of which includes an electrode lead 114. The battery cells 112 may be, but are not limited to, pouch-type battery cells having a plate shape. The electrode lead 114 is a positive electrode lead or a negative electrode lead, and the end of the electrode lead 114 of each battery cell 112 may be bent in one direction so as to come into contact with the end of the electrode lead of another adjacent battery cell 112. Two electrode leads 114 that come into contact with each other may be fixed to each other by welding or the like, thereby establishing an electrical connection between the battery cells 112 inside the battery cell assembly 400.

[0036] In addition, a bus bar frame 500 may be provided that is housed in the module frame 210 together with the battery cell assembly 400. The bus bar frame 500 may include an upper frame 510 located on top of the cell assembly 400, a front frame 520 located on the front side of the battery cell assembly 400, and a rear frame 530 located on the rear side of the battery cell assembly 400, and bus bars 540 connected to the electrode leads 114 of the battery cells that make up the battery cell assembly 400 may be mounted on the front frame 520 and the rear frame 530.

[0037] A plurality of battery cells 112 are stacked vertically with their electrode leads 114 aligned in one direction to form a battery cell assembly 400. The battery cell assembly 400 is housed in a module frame 120 having at least one opening extending in the length direction of the battery cell assembly 400. The electrode leads 114 are extended to the outside of the module frame 210 through the opening, and the extended electrode leads 114 are coupled to the front frame 520 and rear frame 530 of the bus bar frame 500, respectively, to be electrically connected to the bus bars 540 mounted thereon. The bus bar frame 500 may be made of an insulating material, for example, a non-conductive synthetic resin, and the bus bars 540 may be made of a conductive metal material.

[0038] The battery module 100 may include a flexible printed circuit board (FPCB) (not shown) that is attached to the module frame 210 and extends in the length direction from the top of the battery cell assembly 400 and is configured to sense the battery cells 112. The battery module 100 may also include various electrical components, such as an internal circuit board (ICB) and a battery management system (BMS). The electrical components, such as the ICB and BMS board, may be electrically connected to the plurality of battery cells 112.

[0039] The battery module 100 may further include a thermally conductive resin layer 700 positioned between the lower surface of the battery cell assembly 400 and the module frame 210. The thermally conductive resin layer 700 is formed by injecting a thermally conductive resin and may serve to transfer heat generated from the battery cell assembly 400 to the bottom surface of the battery module 100 and to fix the cell assembly 400 within the battery module 100.

[0040] Meanwhile, a heat sink 800 may be provided on the side of the battery cell assembly 400 and housed together in the module frame 210, but this is not particularly limited.

[0041] Although the configuration of the battery module 100 has been described above, the shape and configuration are not limited to this, and the shape and configuration can be changed depending on the situation.

[0042] Next, a battery pack 10 according to an embodiment of the present invention will be described with reference to FIGS.

[0043] The battery pack 10 includes one or more battery modules 100, a housing 11 that houses these, and a plurality of valves 20 that are formed on the housing 11 and configured to be openable and closable.

[0044] The housing 11 may include a pack frame (not shown) in which one or more battery modules 100 are arranged, and an upper plate that is coupled to the pack frame to seal the battery modules 100, but the configuration is not limited thereto and any appropriate structure that can protect the battery modules 100 from the outside can be adopted.

[0045] The plurality of valves 20 formed in the housing 11 are openable and closable valves and may include a first valve to an n-th valve. In this embodiment, the first valve 21, the second valve 22, the third valve 23, and the fourth valve 24 are illustrated as being included, but the present invention is not limited thereto, and an appropriate number of valves 20 may be included in consideration of the capacity and number of battery modules 100 included in the battery pack 10, the opening pressure of each valve 20, and the like.

[0046] The valves 20 are configured to be individually opened and closed according to predetermined opening and closing pressures, respectively. In particular, the opening pressures are configured to increase in order from the first valve to the n-th valve, and the opening pressures of the valves 20 are 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 destroyed, i.e., explodes.

[0047] This will be explained in more detail with reference to FIG.

[0048] 3, when thermal propagation occurs inside battery pack 10 and the internal pressure rises, first valve 21 is opened to reduce gas to the outside, thereby suppressing the rise in internal pressure. However, if gas continues to be generated, the internal pressure may continue to rise even with first valve 21 open. When the opening pressure of second valve 22 is reached, second valve 22 is also opened to discharge the internal gas.

[0049] If the valves 20 are opened in this order, and internal gas generation is interrupted while the x-th valve, e.g., the third valve 23, is open, the third valve 23 is closed as the internal pressure drops. As the internal pressure continues to drop and reach the closing pressure of the second valve 22, the second valve 22 is closed. If the valves were not closed and remained open, the internal pressure would continue to drop, eventually reaching the external oxygen inflow pressure. The inflow of oxygen from the outside would promote combustion within the battery pack 10, causing flames to break out and spread to the outside, which is undesirable. However, in the present invention, the valves 20 are opened in order, and even if a pressure drop occurs while the valves are open, they are closed again in order, preventing the pressure from dropping to the oxygen inflow pressure. This prevents combustion within the battery pack 10 and improves safety.

[0050] On the other hand, if the internal pressure continues to rise even with the xth valve open, the nth valve, which is the fourth valve 24 in this drawing, is opened. The opening pressure of this valve can be set to a pressure close to the pressure at which the housing 11 may be destroyed. Therefore, by opening the nth valve, gas can be discharged to the outside and the internal pressure can be reduced before the internal pressure reaches the housing destruction pressure. This prevents the internal pressure of the battery pack 10 from reaching the housing destruction pressure and prevents the housing from being destroyed, i.e., the battery pack 10 from exploding due to the internal pressure.

[0051] After the nth valve, in this embodiment the fourth valve 24, is closed, the internal pressure decreases, and as the internal pressure decreases, the previous valves are closed in sequence, preventing a sudden decrease in the internal pressure. At the same time, combustion within the battery pack 10 ends during this process, and the thermal runaway phenomenon is terminated, so the thermal runaway state can be terminated without destruction of the housing 11 or external propagation of the internal combustion.

[0052] By stably terminating the thermal runaway state in this manner, the thermal runaway state can be terminated without destruction or explosion of the housing 11 of the battery pack 10, thereby preventing heat propagation to the outside and improving the safety of the battery pack 10. Furthermore, in this embodiment, the multiple valves 20 do not simultaneously open when the internal pressure increases or are unable to close after opening, but rather sequentially open as the pressure increases and close as the pressure decreases, thereby preventing explosion due to the inflow of external oxygen. That is, if the valves simultaneously open or are unable to close after opening, and all the valves remain open even when the pressure decreases, the internal pressure may suddenly drop, causing a sudden inflow of oxygen from the outside, which could result in an explosion. However, according to this embodiment, the valves are opened and closed in a sequential manner, thereby maintaining the internal pressure within a certain range, thereby preventing explosion.

[0053] Specific examples of valves that can be used in the present invention will be described below with reference to FIGS.

[0054] FIG. 4 is a diagram showing a schematic diagram of the structure and opening / closing process of the valve in the battery pack of FIG. 2, FIG. 5 is a diagram showing a schematic diagram of the structure and opening / closing process of the valve in a battery pack of another embodiment of the present invention, and FIG. 6 is an enlarged diagram of VI in FIG. 5.

[0055] 4, a valve 20 according to an embodiment of the present invention may include a valve body 30 including a first flange 31 located outside the housing 11, a second flange 32 located inside the housing 11, and a connecting portion 33 connecting the first and second flanges 31, 32. A gasket 60 may be located along the periphery of the inside of the first flange 31, and a support portion 40 is located between the gasket 60 and the housing 11, and is in contact with the gasket 60 when no internal pressure is applied. In addition, an elastic portion 50, which may be formed of a spring or the like, is located between the inner surface of the housing 11 and the second flange 32, surrounding the connecting portion 33.

[0056] With this structure, when internal pressure is applied, the elastic portion 50 compresses, opening the valve 20. That is, (a) on the left side of FIG. 4 shows the valve 20 in a closed state before internal pressure is applied. When internal pressure is applied to the second flange portion 32 in this state, the elastic portion 50 compresses and pushes the valve body portion 30 outward, causing the gasket 60 and support portion 40 to separate, as shown in (b) on the right side, opening the valve 20. When the internal pressure decreases in this state and reaches the closing pressure of the valve 20, the compression of the elastic portion 50 is released, returning the valve 20 to the state shown in (a), closing the valve 20. In this way, the magnitude of the internal pressure that opens and closes 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.

[0057] Meanwhile, as shown in FIG. 5, the valve 20 may include a sensor unit 70 instead of the elastic unit 50 to control opening and closing. That is, in a valve 20 according to another embodiment of the present invention, the sensor unit 70 is provided inside the support unit 40, i.e., on the surface communicating with the interior of the housing 11. The sensor unit 70 causes the valve body 30 to move toward and away from the housing 11, thereby opening and closing the valve 20. That is, FIG. 5(a) shows a state in which the valve body 30 is positioned toward the inside of the housing 11 and the gasket 60 is in contact with the support unit 40, thereby closing the valve 20. FIG. 5(b) shows a state in which the valve body 30 is moved toward the outside of the housing 11, thereby opening the valve. In this case, the valve 20 may further include a gas communication hole 34 in the second flange unit 32 to form a gas passage, particularly in the open state shown in FIG. 5(b).

[0058] 6, the sensor unit 70 that controls the opening and closing of the valve 20 may include a sensing wire 71 disposed inside a sensing hole 41 formed on the inner surface of the support unit 40, and first and second sensors 72 and 73. The sensing wire 71 may sink into the sensing hole 41 due to internal pressure, and thus, whether or not the internal pressure is rising can be determined based on whether or not it comes into contact with the sensor.

[0059] Specifically, in a steady state, the sensing wire 71 is located at position 71a in the drawing and does not come into contact with sensors 72 and 73, maintaining the valve 20 in a closed state. When the internal pressure causes the sensing wire 71 to collapse inward to position 71b in the drawing, it comes into contact with both the first and second sensors 72 and 73, and the valve 20 is controlled to maintain an open state. As the internal pressure decreases and the sensing wire 71 returns to position 71a, it first loses contact with the second sensor 73, and then loses contact with the first sensor 72, causing the valve 20 to close again. When the opening and closing of the valve 20 is controlled using the sensor unit 70 in this way, the opening and closing pressure of the valve 20 can be set differently by changing the settings of sensors 72 and 73.

[0060] As described above, the battery pack according to the embodiment of the present invention is provided with multiple valves that can be opened and closed sequentially. Therefore, even if thermal runaway occurs inside the battery pack and the internal pressure rises, the multiple valves can be opened and closed sequentially to prevent the housing from being destroyed and external oxygen from entering, thereby preventing the battery pack from exploding and improving safety.

[0061] The battery pack described above can be applied to various devices, including transportation means such as electric bicycles, electric cars, and hybrid cars, but the present invention is not limited thereto and can be applied to various devices that can use battery modules and battery packs including the same, which also fall within the scope of the present invention.

[0062] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention. [Explanation of symbols]

[0063] 100 battery modules 10 Battery pack 20 valves 30 Valve body 40 Support part 50 Elastic part 60 gaskets 70 Sensor section

Claims

1. a plurality of battery modules; and a housing for accommodating the plurality of battery modules; Including, the housing includes a plurality of valves that can be opened and closed; The plurality of valves are configured to open and close sequentially in response to the internal pressure of the battery pack.

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

3. 3. The battery pack according to claim 2, wherein the nth valve is opened as the pressure inside the housing increases while the first to (n-1)th valves are open.

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

5. Any of the plurality of valves is a valve body including a first flange portion located outside the housing, a second flange portion located inside the housing, and a connecting portion connecting the first flange portion and the second flange portion; an elastic portion formed to surround the connecting portion at a position between the second flange portion and the housing; The battery pack according to any one of claims 1 to 4, comprising:

6. The battery pack according to claim 5 , wherein when the pressure inside the housing increases, the valve is opened by applying pressure to the second flange portion and compressing the elastic portion.

7. The battery pack according to claim 5 , wherein the plurality of valves have different opening pressures by varying at least one of the size of the valve body and the elastic force of the elastic portion.

8. Any of the plurality of valves is a valve body including a first flange portion located outside the housing, a second flange portion located inside the housing, and a connecting portion connecting the first flange portion and the second flange portion; a support portion disposed between the first flange portion and the housing; and a sensor portion formed on one surface of the support portion facing the inside of the housing; The battery pack according to any one of claims 1 to 4, comprising:

9. The battery pack according to claim 8 , wherein the second flange portion further includes a gas communication hole that forms a discharge passage for internal gas when the valve is open.

10. The sensor unit a sensing hole formed in a recessed shape on one surface of the support; a sensing wire disposed inside the sensing hole; and at least one sensor configured to make graduated contact with the sensing wire; The battery pack of claim 9 , comprising:

11. A device comprising at least one battery pack according to claim 1.

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