Battery module and battery pack including same

Abstract

A battery module according to one embodiment of the present invention includes a battery cell stack including a plurality of first battery cells and at least one second battery cell inserted between the plurality of first battery cells; a module frame accommodating the battery cell stack; and temperature sensors located inside the module frame for respectively detecting abnormalities in the plurality of first battery cells and the at least one second battery cell, wherein the second battery cell has a lower resistance than the first battery cell.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0089361, filed July 10, 2023, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a battery module and a battery pack including the same, and more particularly to a battery module in which battery cells with relatively low resistance are inserted into a battery cell stack included in the battery module, and a battery pack including the same, and in particular to a battery module and a battery pack including the same in which, when an abnormality is detected in some battery cells included in the battery module, the battery cells with relatively low resistance are discharged at a faster rate, thereby delaying heat transfer between the battery cells. [Background technology]

[0003] Secondary batteries, which are easily applicable to various products and have electrical properties such as high energy density, are widely used not only in portable devices but also in electric vehicles or hybrid vehicles powered by electrical sources, power storage devices, etc. Such secondary batteries are attracting attention as a new energy source that is environmentally friendly and improves energy efficiency because they do not produce any by-products due to energy use, in addition to the primary benefit of dramatically reducing the use of fossil fuels.

[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] Generally, lithium secondary batteries can be classified into cylindrical or prismatic 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 an aluminum laminated sheet pouch, depending on the shape of the exterior material.

[0006] Recently, as secondary batteries are increasingly used as energy storage sources, the need for large-capacity secondary battery structures has increased, leading to an increased demand for medium- to large-sized modular battery packs, which are composed of battery modules in which multiple secondary batteries are connected in series or parallel. These battery modules improve capacity and output by connecting multiple battery cells in series or parallel to form a battery cell stack. Additionally, multiple battery modules can be mounted together with various control and protection systems, such as a Battery Management System (BMS) and a cooling system, to form a battery pack.

[0007] Since a battery pack is composed of multiple battery modules, if some of the battery modules are overvoltage, overcurrent, or overheated, the safety and operating efficiency of the battery pack may become an issue. In particular, as the capacity of battery packs gradually increases to improve driving distance, the energy inside the pack also increases. As a result, it is necessary to design a structure that meets stricter safety standards and ensures the safety of the vehicle and driver.

[0008] In this regard, there is an emerging need to develop a battery module that can mitigate or delay the occurrence of heat propagation between battery cells when a thermal runaway phenomenon occurs in some battery cells within the battery module. Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a battery module in which battery cells with relatively low resistance are inserted into a battery cell stack included in the battery module, and a battery pack including the same, and in particular, to provide a battery module and a battery pack including the same in which, when an abnormality is detected in some battery cells included in the battery module, the battery cells with relatively low resistance are discharged at a faster rate, thereby delaying heat transfer between the battery cells.

[0010] The problems to be solved by the present invention are not limited to those described above, and problems not mentioned will be clearly understood by those skilled in the art to which the present invention pertains from this specification and the accompanying drawings. [Means for solving the problem]

[0011] A battery module according to one embodiment of the present invention includes a battery cell stack including a plurality of first battery cells with at least one second battery cell inserted between the plurality of first battery cells; a module frame accommodating the battery cell stack; and temperature sensors located within the module frame for detecting abnormalities in the plurality of first battery cells and the at least one second battery cell, respectively, wherein the second battery cell has a resistance smaller than that of the first battery cell. The second battery cell may have a resistance that is half or smaller than that of the first battery cell.

[0012] The battery cell may include at least one first bus bar that electrically connects the positive and negative terminals of the plurality of first battery cells to each other, and at least one second bus bar that electrically connects the positive and negative terminals of the at least one second battery cell to each other.

[0013] Positive and negative terminals included in the plurality of first battery cells and the at least one second battery cell may protrude toward an upper portion of the module frame.

[0014] At least one metal member may be located between the at least one second bus bar and the module frame, and the at least one metal member may be connected to at least one moving member fixed to the module frame.

[0015] The metal member may extend along the at least one second bus bar positioned adjacent to each other.

[0016] The metal member may have a rod shape made of copper (Cu).

[0017] The moving member may be made of ceramic.

[0018] The at least one second bus bar and the at least one metal member may be spaced apart from each other, and the plurality of first battery cells and the at least one second battery cell may be connected in series to each other.

[0019] When the temperature sensor detects an abnormality in any one of the plurality of first battery cells and the at least one second battery cell, the moving member can lower the metal member toward the at least one second bus bar.

[0020] When the moving member lowers the metal member toward the at least one second bus bar, the metal member and the at least one second bus bar are electrically connected to each other, and the positive terminal and the negative terminal of the at least one second battery cell can be connected in parallel to each other.

[0021] A battery pack according to another embodiment of the present invention includes the above-described battery module. [Effects of the Invention]

[0022] According to an embodiment, the present invention provides a battery module in which battery cells having relatively low resistance are inserted into a battery cell stack included in the battery module, and a battery pack including the same. In particular, when an abnormality is detected in some battery cells included in the battery module, the battery cells having relatively low resistance are discharged at a faster rate, thereby delaying heat transfer between the battery cells.

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

[0024] [Figure 1] 1 is a top view of a battery module with an upper portion of a module frame removed. [Figure 2] 2 is a perspective view showing a portion of a battery cell stack included in the battery module of FIG. 1 in a normal state. [Figure 3] 2 is a perspective view showing a portion of a battery cell stack included in the battery module of FIG. 1 when a thermal runaway phenomenon occurs. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily understand and practice the various embodiments of the present invention. The present invention may be embodied in several different forms and is not limited to the embodiments described herein.

[0026] 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.

[0027] 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.

[0028] Also, throughout the specification, when a part is said to "comprise" a certain element, this means that it can further include other elements, rather than excluding other elements, unless otherwise specified.

[0029] Furthermore, throughout the specification, "on a plane" means a view of the target part from above, and "on a cross section" means a view of the target part cut vertically from the side.

[0030] Hereinafter, a battery module according to an embodiment of the present invention will be described.

[0031] FIG. 1 is a top view of a battery module with the upper part of the module frame removed.

[0032] Referring to FIG. 1, a battery module 100 according to one embodiment of the present invention includes a battery cell stack 130 including a plurality of first battery cells 110 with at least one second battery cell 120 inserted between the plurality of first battery cells 110; a module frame 200 accommodating the battery cell stack 130; and a temperature sensor 500 located inside the module frame 200 and detecting whether or not there is an abnormality in the plurality of first battery cells 110 and at least one second battery cell 120.

[0033] The battery cell stack 130 may include a plurality of first battery cells 110 and at least one second battery cell 120. Here, the battery cell stack 130 may be formed by stacking the plurality of first battery cells 110 and the at least one second battery cell 120 in one direction.

[0034] The stacking direction in the battery cell stack 130 may be a direction from one side surface of the module frame 200 to the other side surface, and the one side surface and the other side surface of the module frame 200 may be two surfaces facing each other based on the length direction of the module frame 200. For example, as shown in FIG. 1 , in the battery cell stack 130, the plurality of first battery cells 110 and at least one second battery cell 120 may be stacked in a direction toward both side surfaces of the module frame 200 facing each other on the y axis.

[0035] For example, the plurality of first battery cells 110 and the at least one second battery cell 120 may be pouch-shaped, prismatic, or jellyroll-shaped cylindrical battery cells. Preferably, pouch-shaped or prismatic batteries are used, and a battery cell stack 130 including the plurality of battery cells may be formed in a limited space inside the battery module 100. However, the present invention is not limited thereto, and any shape that can be easily accommodated inside the module frame 200 may be used.

[0036] When the plurality of first battery cells 110 and the at least one second battery cell 120 included in the battery cell stack 130 are pouch-type battery cells, the plurality of first battery cells 110 and the at least one second battery cell 120 may be manufactured by placing an electrode assembly in a pouch case made of a laminate sheet including a resin layer and an intermediate layer, and then heat-sealing the sealing portion of the pouch case. As an example, the plurality of first battery cells 110 and the at least one second battery cell 120 may be formed in a rectangular sheet-type structure. The number of the plurality of first battery cells 110 and the at least one second battery cell 120 may be adjusted as needed.

[0037] In the battery cell stack 130, at least one second battery cell 120 may be inserted between adjacent first battery cells 110 among the plurality of first battery cells 110. For example, as shown in FIG. 1, the battery cell stack 130 may have a pair of second battery cells 120 inserted between adjacent first battery cells 110 among the plurality of first battery cells 110. However, the present invention is not limited thereto, and the position of the at least one second battery cell 120 or the number of second battery cells 120 inserted between adjacent first battery cells 110 may be adjusted as needed.

[0038] The second battery cell 120 may have a resistance smaller than that of the first battery cell 110. For example, the second battery cell 120 may have a resistance that is half or smaller than that of the first battery cell 110. More specifically, the second battery cell 120 may be manufactured using the same components as the first battery cell 110, but the thickness of the positive and negative electrodes, the loading amount of the positive and negative active materials, the battery capacity, etc. included in the second battery cell 120 may be smaller than that of the first battery cell 110. For example, the second battery cell 120 may be manufactured using the same components as the first battery cell 110, but the thickness of the positive and negative electrodes, the loading amount of the positive and negative active materials, the battery capacity, etc. included in the second battery cell 120 may be smaller by approximately 50% or less based on that of the first battery cell 110.

[0039] Therefore, in the battery module 100 according to this embodiment, when the plurality of first battery cells 110 and at least one second battery cell 120 included in the battery cell stack 130 are rapidly discharged, the second battery cell 120, which has a relatively low resistance, generates less heat and has a relatively faster discharge rate, so the second battery cell 120 can have a relatively lower temperature than the first battery cell 110.

[0040] In particular, if an abnormal phenomenon such as thermal runaway occurs in some of the plurality of first battery cells 110 and the at least one second battery cell 120, the second battery cell 120 can be rapidly discharged at a relatively fast rate, thereby preventing or delaying heat propagation that may occur within the battery module 100. Furthermore, the electrical energy obtained by rapidly discharging the plurality of first battery cells 110 and the at least one second battery cell 120 can be used to operate a cooling system (not shown) that can cool the battery module 100, thereby more effectively preventing or delaying heat propagation that may occur within the battery module 100.

[0041] The battery module 100 may include a module frame 200 that houses the battery cell stack 130. Referring to FIG. 1 , the battery module 100 is illustrated with the upper portion of the module frame 200 omitted. This is omitted for convenience of explanation; the module frame 200 may also include an upper portion of the module frame that covers the upper portion of the battery cell stack 130. For example, the module frame 200 may be a monoframe formed of a metal plate with its top, bottom, and both side surfaces integrated together. For another example, the module frame 200 may include a lower frame formed of a metal plate with its bottom and both side surfaces integrated together, and an upper cover that covers the upper surface of the lower frame. For another example, the module frame 200 may be a frame formed by combining two L-shaped frames. For another example, the module frame 200 may be a four-plate frame formed by combining an upper plate, a lower plate, a left plate, and a right plate. However, the present embodiment is not limited thereto, and any frame shape that can protect the internal components of the battery module 100 may be applicable.

[0042] Here, the components of the module frame 200 may be joined by welding or fixed to each other with corresponding corners in contact with each other, or may be fixed to each other using other fastening members. Also, the components of the module frame 200 may be made of a metal material having a predetermined strength.

[0043] The battery module 100 may include a temperature sensor 500 located inside the module frame 200. For example, as shown in Fig. 2, the temperature sensor 500 may be attached to the inner surface of the module frame 200. However, the location of the temperature sensor 500 inside the module frame 200 is not limited thereto, and any location that can sense the temperatures of the plurality of first battery cells 110 and at least one second battery cell 120 may be applied to this embodiment.

[0044] The temperature sensor 500 can detect whether or not there is an abnormality in each of the plurality of first battery cells 110 and at least one second battery cell 120 included in the battery cell stack 130. For example, the temperature sensor 500 can be a component such as a thermistor or a thermocouple. Here, the thermocouple can be a K-type or a T-type. However, the present invention is not limited thereto, and any sensor that can detect the temperatures of the plurality of first battery cells 110 and at least one second battery cell 120 inside the battery module 100 can be applied to this embodiment.

[0045] As a result, in the battery module 100 according to this embodiment, the temperature sensor 500 is positioned inside the module frame 200, so that the temperature of the plurality of first battery cells 110 and at least one second battery cell 120 can be easily sensed, and the occurrence of an abnormal phenomenon (for example, a thermal runaway phenomenon) in a specific battery cell among the plurality of first battery cells 110 and at least one second battery cell 120 can be quickly sensed.

[0046] Fig. 2 is a perspective view showing a part of a battery cell stack included in the battery module of Fig. 1 in a normal state, and Fig. 3 is a perspective view showing a part of a battery cell stack included in the battery module of Fig. 1 when a thermal runaway phenomenon occurs.

[0047] 1 and 2, in the battery cell stack 130, a plurality of first battery cells 110 and at least one second battery cell 120 may be connected in series with each other.

[0048] More specifically, the battery pack may further include a plurality of bus bars 150 that electrically connect the plurality of first battery cells 110 and the at least one second battery cell 120 to each other. The bus bars 150 may electrically connect the positive and negative terminals included in different battery cells of the plurality of first battery cells 110 and the at least one second battery cell 120 to each other. In other words, the plurality of bus bars 150 may connect the positive and negative terminals included in the plurality of first battery cells 110 and the at least one second battery cell 120 to each other in series.

[0049] Here, serial connection means electrically connecting the positive and negative terminals of different first battery cells 110, as shown in Figures 1 and 2, electrically connecting the positive or negative terminal of the first battery cell 110 to the negative or positive terminal of the second battery cell 120, or electrically connecting the positive and negative terminals of different second battery cells 120.

[0050] The plurality of bus bars 150 may include at least one first bus bar 151 that connects the positive and negative terminals of the plurality of first battery cells 110 in series with each other, and at least one second bus bar 155 that connects the positive and negative terminals of at least one second battery cell 120 in series with each other.

[0051] More specifically, the at least one first bus bar 151 may serially connect the positive and negative terminals of a pair of adjacent first battery cells 110 among the plurality of first battery cells 110. The at least one second bus bar 155 may serially connect the positive and negative terminals of a pair of adjacent second battery cells 120 among the at least one second battery cell 120. Furthermore, the at least one second bus bar 155 may serially connect the positive or negative terminal of the second battery cell 120 to the negative or positive terminal of the first battery cell 110 adjacent to the second battery cell 120.

[0052] 1 and 2, the bus bar 150 may have a rectangular shape. However, the shape of the bus bar 150 is not limited thereto, and any shape that can electrically connect positive and negative terminals included in different battery cells to each other may be applied to this embodiment.

[0053] 1 and 2, in the battery module 100 according to this embodiment, the positive and negative terminals included in the plurality of first battery cells 110 and the at least one second battery cell 120 may protrude toward the top of the module frame 200. That is, the plurality of first battery cells 110 and the at least one second battery cell 120 may be unidirectional battery cells in which the positive and negative terminals protrude in one direction. Here, the plurality of first battery cells 110 and the at least one second battery cell 120 may be arranged such that the positive and negative terminals face the top of the module frame 200.

[0054] In this case, the plurality of bus bars 150 may be positioned between the battery cell stack 130 and the module frame 200. More specifically, as shown in Figures 1 and 2, the plurality of bus bars 150 may be positioned on the positive and negative terminals included in the plurality of first battery cells 110 and at least one second battery cell 120, respectively. That is, the plurality of bus bars 150 may be disposed at positions that allow the positive and negative terminals included in the plurality of first battery cells 110 and at least one second battery cell 120 to be connected in series with each other.

[0055] 1 to 3, in the battery module 100 according to this embodiment, at least one metal member 300 may be located between the plurality of bus bars 150 and the upper portion of the module frame 200. More specifically, at least one metal member 300 may be located on at least one second bus bar 155. For example, as shown in FIGS. 1 and 2, at least one metal member 300 may be located on a plurality of second bus bars 155 that are located adjacent to each other.

[0056] As one example, the metal member 300 may be a single member extending along a plurality of adjacent second bus bars 155. As another example, the metal member 300 may be a single member located on a pair of adjacent second bus bars 155 and extending along the pair of second bus bars 155.

[0057] For example, the metal member 300 may be a rod-shaped member made of copper (Cu), aluminum (Al), gold, silver, etc. However, the material and shape of the metal member 300 are not limited thereto, and any metal member 300 may be included in this embodiment as long as it is made of a material and has a shape that is mutually conductive with the plurality of second bus bars 155.

[0058] 1 to 3, at least one metal member 300 may be connected to at least one moving member 400 fixed to the upper part of the module frame 200. More specifically, one end of the moving member 400 may be fixed to the metal member 300, and the other end of the moving member 400 may be fixed to the upper part of the module frame 200.

[0059] When the temperature sensor 500 detects an abnormality in either the plurality of first battery cells 110 or at least one second battery cell 120, the moving member 400 can lower the metal member 300 toward the plurality of bus bars 150. For example, the moving member 400 is connected to a driving means such as a motor (not shown) attached to the upper part of the module frame 200, and the moving member 400 can raise or lower the metal member 300 according to the internal conditions of the battery module 100.

[0060] For example, the moving member 400 may be made of ceramic, rubber, plastic, glass fiber, quartz, etc. However, the material of the moving member 400 is not limited to these, and any non-conductive material that can cut off the electrical connection between the metal member 300 and the module frame 200 may be included in this embodiment.

[0061] When the inside of the battery module 100 is in a normal state, the metal member 300 may be spaced apart from the plurality of bus bars 150 as shown in Fig. 2. However, when an abnormal phenomenon (e.g., a thermal runaway phenomenon) occurs inside the battery module 100, the metal member 300 may come into contact with and be electrically connected to a second bus bar 155 of the plurality of bus bars 150 as shown in Fig. 3. That is, when the moving member 400 moves the metal member 300 downward toward at least one second bus bar 155, the metal member 300 and the at least one second bus bar 155 are electrically connected to each other, and the positive and negative terminals of at least one second battery cell 120 may be connected in parallel to each other.

[0062] As a result, in the battery module 100 according to this embodiment, if an abnormal phenomenon occurs inside the battery module 100, the metal members 300 are electrically connected to the plurality of second bus bars 155, respectively, so that at least one second battery cell 120 that is already connected in series can be connected in parallel with each other.

[0063] That is, the electrical connection state of the at least one second battery cell 120 can be changed from a series connection to a parallel connection by the metal member 300, and the resistance of the at least one second battery cell 120 can be relatively lower than in a series connection state. In this case, when the battery module 100 is rapidly discharged, the resistance of the at least one second battery cell 120 is relatively lower than in a series connection state, so the at least one second battery cell 120 can be discharged more quickly and the amount of heat generated by the at least one second battery cell 120 is also reduced. In other words, by changing the electrical connection state in this manner, the battery module 100 according to this embodiment can more effectively prevent or delay heat propagation when an abnormality occurs inside the battery module 100.

[0064] A battery pack according to another embodiment of the present invention includes the battery module described above. Meanwhile, one or more battery modules according to this embodiment may be packaged in a pack case to form a battery pack.

[0065] The battery module and the battery pack including the same 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 the battery module and the battery pack including the same, which also fall within the scope of the present invention.

[0066] 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]

[0067] 100 battery modules 110 First battery cell 120 Second battery cell 130 Battery cell stack 150 busbar 200 Module Frame 300 Metallic materials 400 Moving parts 500 Temperature Sensor

Claims

1. a battery cell stack including a plurality of first battery cells, with at least one second battery cell interposed between the plurality of first battery cells; a module frame that houses the battery cell stack; and temperature sensors located inside the module frame for detecting abnormalities in the plurality of first battery cells and the at least one second battery cell, respectively; The second battery cell has a lower resistance than the first battery cell.

2. The battery module according to claim 1 , wherein the second battery cell has a resistance that is half or less than the resistance of the first battery cell.

3. 2. The battery module of claim 1, further comprising: at least one first bus bar electrically connecting positive and negative terminals of the plurality of first battery cells to each other; and at least one second bus bar electrically connecting positive and negative terminals of the at least one second battery cell to each other.

4. The battery module of claim 3 , wherein positive and negative terminals included in the plurality of first battery cells and the at least one second battery cell protrude toward an upper portion of the module frame.

5. at least one metal member is positioned between the at least one second bus bar and the module frame; The battery module according to claim 3 , wherein the at least one metal member is respectively connected to at least one moving member fixed to the module frame.

6. The battery module according to claim 5 , wherein the metal member extends along the at least one second bus bar positioned adjacent to each other.

7. The battery module according to claim 6 , wherein the metal member has a rod shape and is made of copper (Cu).

8. The battery module according to claim 5 , wherein the moving member is made of ceramic.

9. the at least one second bus bar and the at least one metal member are spaced apart from each other; The battery module of claim 5 , wherein the plurality of first battery cells and the at least one second battery cell are connected in series with each other.

10. When an abnormality is detected in at least one of the plurality of first battery cells and the at least one second battery cell through the temperature sensor, The battery module of claim 9 , wherein the moving member lowers the metal member toward the at least one second bus bar.

11. When the moving member moves the metal member downward toward the at least one second bus bar, The battery module according to claim 10 , wherein the metal member and the at least one second bus bar are electrically connected to each other, and a positive terminal and a negative terminal of the at least one second battery cell are connected in parallel to each other.

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

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