Battery pack

Abstract

According to exemplary embodiments, a battery pack is provided. The battery pack comprises: a lower frame including a base plate and sidewalls; first to fourth battery cell assemblies, which are arranged on the lower frame and include a plurality of battery cells; a first cross beam interposed between the first and second battery cell assemblies, the first and second battery cells being spaced apart from each other in a first direction; a second cross beam interposed between the third and fourth battery cell assemblies, the third and fourth battery cell assemblies being spaced apart from the first and second battery cell assemblies in a second direction that is perpendicular to the first direction; first fixing units coupled to the first cross beam and spaced apart from the base plate; and second fixing units coupled to the first fixing units.

Description

battery pack

[0001] The present invention relates to a housing and a battery pack including the housing. This application claims the benefit of Korean Application No. 10-2023-0160157, filed November 20, 2023, which is incorporated herein by reference in its entirety.

[0002] Unlike primary batteries, secondary batteries can be charged and discharged multiple times. They are widely used as a power source for various wireless devices, including handsets, laptops, and cordless vacuum cleaners. Recently, improved energy density and economies of scale have dramatically reduced the per-unit manufacturing cost of secondary batteries. Furthermore, as the range of battery electric vehicles (BEVs) has increased to match that of fuel-powered vehicles, the primary use of secondary batteries is shifting from mobile devices to mobility.

[0003] The technological development trend for secondary batteries for mobility is improving energy density and safety. The safety of secondary batteries for mobility is crucial, as it directly impacts the lives of passengers. Safety in secondary batteries can be achieved through mechanical robustness, reliable electrical insulation, and delayed heat transfer in the event of thermal runaway.

[0004] The technical idea of ​​the present invention aims to solve a problem by providing a battery pack with improved safety and energy density.

[0005] According to exemplary embodiments of the present invention for solving the above-described problem, a battery pack is provided. The battery pack includes a lower frame including a base plate and side walls; first to fourth battery cell assemblies disposed on the lower frame and including a plurality of battery cells; a first cross beam interposed between the first and second battery cell assemblies, wherein the first and second battery cells are spaced apart in a first direction; a second cross beam interposed between the third and fourth battery cell assemblies, wherein the third and fourth battery cell assemblies are spaced apart from the first and second battery cell assemblies in a second direction perpendicular to the first direction; first fasteners coupled to the first cross beam and spaced apart from the base plate; and second fasteners coupled to the first fasteners.

[0006] The battery pack further includes leads coupled to the side walls.

[0007] The battery pack further includes gaskets interposed between the second fixing members and the leads.

[0008] Each of the second fixtures includes a flange, the flange including a groove having a depth less than the height of each of the gaskets, and the gaskets are disposed in the groove.

[0009] The above battery pack further includes a center bracket disposed on the lead.

[0010] A battery pack characterized in that the center bracket is coupled to the second fixing members.

[0011] The battery pack further includes third fasteners coupled to the second fasteners and in contact with the center bracket.

[0012] A first end of the center bracket is fixed to the first cross beam, and a second end of the center bracket is fixed to the second cross beam.

[0013] The above lead is fixed by the above center bracket.

[0014] The battery pack further includes a center beam interposed between the first and second battery cell assemblies.

[0015] The above center beam overlaps the above center bracket.

[0016] The above center beam is perpendicular to the above center bracket.

[0017] Each of the second fixtures includes a first cylindrical portion; a flange portion having a diameter larger than that of the first cylindrical portion; a hexagonal portion spaced apart from the first cylindrical portion with the flange portion interposed therebetween; and a second cylindrical portion spaced apart from the flange portion with the hexagonal portion interposed therebetween.

[0018] Each of the second fixing members further includes an adhesive applied to the first cylindrical portion.

[0019] The first cylindrical portion of each of the second fixing members is coupled to a corresponding one of the first fixing members.

[0020] According to exemplary embodiments of the present invention, the internal space of a battery pack occupied by the fasteners for securing the center bracket can be minimized. Accordingly, a battery pack with increased energy density can be provided.

[0021] The effects that can be obtained from the exemplary embodiments of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly derived and understood by those skilled in the art to which the exemplary embodiments of the present disclosure pertain from the following description. In other words, unintended effects resulting from practicing the exemplary embodiments of the present disclosure can also be derived by those skilled in the art from the exemplary embodiments of the present disclosure.

[0022] FIG. 1 is a flowchart illustrating a method for manufacturing a battery pack according to exemplary embodiments.

[0023] FIG. 2 is a perspective view illustrating a method of manufacturing a battery pack according to exemplary embodiments.

[0024] Figure 3 is an enlarged partial perspective view of a portion of Figure 2.

[0025] Figure 4 is a cross-sectional view taken along the cutting line 3I-3I' of Figure 3.

[0026] Figure 5 is a cross-sectional view taken along the cutting line 3II-3II' of Figure 3.

[0027] FIG. 6 is a perspective view illustrating a method of manufacturing a battery pack according to exemplary embodiments.

[0028] Fig. 7 is an enlarged partial perspective view of a portion of Fig. 6.

[0029] Fig. 8 is a cross-sectional view taken along the cutting line 7I-7I' of Fig. 7.

[0030] Figure 9 shows the second fixture.

[0031] FIG. 10 is a perspective view illustrating a method of manufacturing a battery pack according to exemplary embodiments.

[0032] Fig. 11 is an enlarged partial perspective view of a portion of Fig. 10.

[0033] Fig. 12 is a cross-sectional view taken along the cutting line 11I-11I' of Fig. 11.

[0034] FIG. 13 is a perspective view illustrating a method of manufacturing a battery pack according to exemplary embodiments.

[0035] Fig. 14 is an enlarged partial perspective view of a portion of Fig. 13.

[0036] Fig. 15 is a cross-sectional view taken along the cutting line 14I-14I' of Fig. 14.

[0037] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concepts of terms to best explain his or her invention, they should be interpreted in a way that aligns with the technical spirit of the present invention.

[0038] Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

[0039] In addition, when describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description is omitted.

[0040] Since the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art, the shapes and sizes of components in the drawings may be exaggerated, omitted, or schematically illustrated for clearer explanation. Accordingly, the sizes and proportions of each component do not fully reflect the actual sizes or proportions.

[0041]

[0042] (Embodiments 1 and 2)

[0043] FIG. 1 is a flowchart illustrating a method for manufacturing a battery pack according to exemplary embodiments.

[0044] FIG. 2 is a perspective view illustrating a method of manufacturing a battery pack according to exemplary embodiments.

[0045] Figure 3 is an enlarged partial perspective view of a portion (POR2) ​​of Figure 2.

[0046] Figure 4 is a cross-sectional view taken along the cutting line 3I-3I' of Figure 3.

[0047] Figure 5 is a cross-sectional view taken along the cutting line 3II-3II' of Figure 3.

[0048] FIG. 6 is a perspective view illustrating a method of manufacturing a battery pack according to exemplary embodiments.

[0049] Fig. 7 is an enlarged partial perspective view of a portion (POR6) of Fig. 6.

[0050] Fig. 8 is a cross-sectional view taken along the cutting line 7I-7I' of Fig. 7.

[0051] Figure 9 shows the second fixture.

[0052] FIG. 10 is a perspective view illustrating a method of manufacturing a battery pack according to exemplary embodiments.

[0053] Fig. 11 is an enlarged partial perspective view of a portion (POR10) of Fig. 10.

[0054] Fig. 12 is a cross-sectional view taken along the cutting line 11I-11I' of Fig. 11.

[0055] FIG. 13 is a perspective view illustrating a method of manufacturing a battery pack according to exemplary embodiments.

[0056] Fig. 14 is an enlarged partial perspective view of a portion (POR13) of Fig. 13.

[0057] Fig. 15 is a cross-sectional view taken along the cutting line 14I-14I' of Fig. 14.

[0058] Referring to FIGS. 1 to 5, in P110, battery cell assemblies can be placed on the lower frame.

[0059] The lower frame (110) may provide a space for mounting battery cell assemblies (120) described below. The lower frame (110) may include a base plate (111) and first to fourth side walls (112, 113, 114, 115). A plurality of cross beams (130) may be provided on the lower frame (110).

[0060] Two directions substantially parallel to the upper surface (111U) of the base plate (111) are defined as the X direction and the Y direction, and a direction substantially perpendicular to the upper surface (111U) of the base plate (111) is defined as the Z direction. Each of the X direction, the Y direction, and the Z direction can be substantially perpendicular to each other. Unless otherwise stated, the definitions of directions are the same for the drawings below.

[0061] The base plate (111) may include a plurality of plates. The plurality of plates may be joined, for example, by friction stir welding. Each of the plurality of plates may include cooling channels, cavities, and ribs. Each of the cooling channels, cavities, and ribs may extend in the X direction.

[0062] Cooling channels can provide a path for cooling fluid to flow. The cooling channels can be spaced apart in the Y direction. The cooling channels can be arranged along the Y direction. The cavities are empty spaces formed within the plurality of plates. The formation of the cavities can reduce the mass of the plurality of plates, thereby increasing the energy density of the battery pack (100, see FIG. 13) including the lower frame (110). The ribs can define the cooling channels and cavities. The ribs can surround the cooling channels and cavities. The ribs can keep the cooling channels and cavities airtight.

[0063] Among the plurality of plates, a centrally located plate may include a center beam (CB). The center beam (111CB) may protrude from the upper surface of the base plate (111). The center beam (111CB) may extend in the X direction.

[0064] The first and second side walls (112, 113) may be coupled to the base plate (111). The first and second side walls (112, 113) may be spaced apart in the Y direction with the base plate (111) therebetween. Each of the first and second side walls (112, 113) may include a plate portion coplanar with the base plate (111), a wall portion perpendicular to the plate portion, and a wing portion on the outer side of the wall portion. The wall portion of each of the first and second side walls (112, 113) may be substantially perpendicular to the Y direction. The wing portion of each of the first and second side walls (112, 113) may include a plurality of coupling holes. The wing portion of each of the first and second side walls (112, 113) may be used for transporting and / or fixing the lower frame (110) (e.g., fixing the lower frame (110) to a vehicle or another battery tray).

[0065] The third and fourth side walls (114, 115) can be coupled to the base plate (111). The third and fourth side walls (114, 115) can be disposed on the base plate (111). The third and fourth side walls (114, 115) can be spaced apart in the X direction. The third and fourth side walls (114, 115) can be substantially perpendicular to the X direction. The third side wall (114) can include a plurality of exhaust holes for installation of exhaust devices.

[0066] A plurality of battery cell assemblies (120) may be arranged on a base plate (111) of a lower frame (110). The base plate (111) may support the plurality of battery cell assemblies (120). The first to fourth side walls (112, 113, 114, 115) may horizontally surround the plurality of battery cell assemblies (120). The first to fourth side walls (112, 113, 114, 115) may protect the plurality of battery cell assemblies (120).

[0067] According to exemplary embodiments, the battery pack (100, see FIG. 13) is of a modular type, and each of the plurality of battery cell assemblies (120) may not include a module frame. Each of the plurality of battery cell assemblies (120) may include a cell stack (121) and a top cover (127).

[0068] The cell stack (121) may include a plurality of banks connected in series with each other. Each of the plurality of banks may include one or more parallel-connected battery cells. The number of serially connected banks and the number of parallel-connected battery cells may be determined depending on the magnitude of the voltage and current to be output from each of the battery cell assemblies (120).

[0069] Battery cells are the basic units of lithium-ion batteries, i.e., secondary batteries. Each battery cell includes an electrode assembly, an electrolyte, and a case. Each battery cell may be any of a cylindrical battery cell, a prismatic battery cell, or a pouch-type battery cell. The electrode assembly of a cylindrical battery cell is housed in a cylindrical metal can. The electrode assembly of a prismatic battery cell is housed in a prismatic metal can. The electrode assembly of a pouch-type battery cell is housed in a pouch case containing an aluminum laminate sheet.

[0070] The electrode assembly may include an anode, a cathode, and a separator interposed between the anode and the cathode. The electrode assembly may be either a jelly-roll type or a stack type. The jelly-roll type electrode assembly may include a winding structure of the anode, the cathode, and the separator interposed therebetween. The stack type electrode assembly may include a plurality of sequentially stacked anodes, a plurality of cathodes, and a plurality of separators interposed therebetween.

[0071] According to exemplary embodiments, the cell stack (121) may further include a plurality of separators. The plurality of separators may prevent swelling of the plurality of battery cells by horizontally supporting the plurality of battery cells. According to exemplary embodiments, the plurality of separators may be thermal barriers. According to exemplary embodiments, each of the plurality of separators may have a high melting temperature and low thermal conductivity. According to exemplary embodiments, each of the plurality of separators may include a flame retardant material, such as a ceramic or coated glass material. According to exemplary embodiments, the plurality of separators may also be configured to release a fire retardant material and a fire extinguishing agent when a thermal runaway event occurs.

[0072] A top cover (127) may be placed on the cell stack (121). The top cover (127) may include, for example, an insulating material. The top cover (127) may cover the cell stack (121).

[0073] Cross beams (130) can isolate a plurality of battery cell assemblies (120) from each other. The cross beams (130) can be interposed between the plurality of battery cell assemblies (120). The plurality of battery cell assemblies (120) can be spaced apart in the X direction with the cross beams (130) interposed therebetween. The cross beams (130) can extend in the Y direction.

[0074] Each of the cross beams (130) may include a plurality of openings (130OP). First fasteners (131) may be coupled to the plurality of openings (130OP). Each of the first fasteners (131) may include a flange (131F) and a modified flange (131DF). Each of the first fasteners (131) may be a blind nut. Each of the first fasteners (131) may be coupled to a corresponding one of the cross beams (130). Each of the first fasteners (131) may be partially embedded in a corresponding one of the cross beams (130). The modified flange (131DF) may be formed in a process of coupling each of the first fasteners (131) to a rib of a corresponding one of the cross beams (130). A plurality of battery cell assemblies (120) may be arranged in the X direction and the Y direction. In Fig. 1, the number of the plurality of battery cell assemblies (120) arranged in the X direction is three, and the number of the plurality of battery cell assemblies (120) arranged in the Y direction is two. Therefore, the arrangement of the plurality of battery cell assemblies (120) can be said to be a 3 * 2 arrangement. A person skilled in the art will be able to easily arrive at a plurality of battery cell assemblies (120) arranged in M ​​* N (wherein, M and N are each integers greater than or equal to 2) based on what is described herein.

[0075] The center beam (111CB) can isolate a plurality of battery cell assemblies (120) in the Y direction. The center beam (111CB) can be interposed between the plurality of battery cell assemblies (120). The center beam (111CB) can be interposed between the cross beams (130). Some of the cross beams (130) can be spaced apart from other some of the cross beams (130) in the Y direction with the center beam (111CB) interposed therebetween.

[0076] Next, referring to FIG. 1 and FIG. 6 to FIG. 9, at P120, second fixing devices (133) can be coupled to first fixing devices (131).

[0077] The second fasteners (133) may be, for example, two-way bolts. Each of the second fasteners (133) may include a first cylindrical portion (Shank) (133S1), a flange (133F), a hexagonal portion (133H), and a second cylindrical portion (133S2).

[0078] The first cylindrical portion (133S1) may have a roughly cylindrical shape. Each of the second fixing members (133) may further include an adhesive (133A) applied to the first cylindrical portion (133S1).

[0079] The flange (133F) may have a roughly disc shape. The diameter of the flange (133F) may be larger than the diameter of the first cylindrical portion (133S1). The flange (133F) may be connected to the first cylindrical portion (133S1). The flange (133F) may include a groove (133G). A corresponding one of the gaskets (135) may be placed in the groove (133G) of the flange (133F) of each of the second fixing members (133). The height of each of the gaskets (135) may be larger than the depth of the groove (133G).

[0080] The hexagonal portion (133H) may have a roughly hexagonal column shape. The hexagonal portion (133H) may be connected to a flange (133F). The hexagonal portion (133H) may be spaced apart from the first cylindrical portion (133S1) with the flange (133F) therebetween.

[0081] The second cylindrical portion (133S2) may have a roughly cylindrical shape. The diameter of the second cylindrical portion (133S2) may be smaller than the diameter of the flange (133F). The second cylindrical portion (133S2) may be connected to the hexagonal portion (133H). The second cylindrical portion (133S2) may be spaced apart from the flange (133F) with the hexagonal portion (133H) interposed therebetween.

[0082] Next, referring to FIG. 1 and FIG. 10 to FIG. 12, at P130, a lead (140) may be provided. The lead (140) may be coupled to the lower frame (110). The lead (140) may be coupled to the first to fourth side walls (112, 113, 114, 115) of the lower frame (110). Gaskets (135) may be interposed between a flange (133F) of a corresponding one of the second fixing members (133) and the lead (140). Accordingly, the gaskets (135) may be pressurized by the lead (140), and thus, a liquid-tight seal may be provided in the internal space defined by the lead (140) and the lower frame (110).

[0083] Next, referring to FIGS. 1 and 13 to 15, at P140, a center bracket (150) may be provided. The center bracket (150) may be fixed by the second and third fixing members (133, 137). The center bracket (150) may be in contact with corresponding ones of the second and third fixing members (133, 137). The center bracket (150) may include a portion interposed between the second and third fixing members (133, 137).

[0084] A battery pack (100) may be provided by providing and combining a center bracket (150). The battery pack (100) may include a lower frame (110), a plurality of battery cell assemblies (120), first to third fixing members (131, 133, 137), gaskets (135), a lid (140), and a center bracket (150).

[0085] The center bracket (150) can be placed on the lead (140). The center bracket (150) can be in contact with the lead (140). The center bracket (150) can fix the lead (140). The center bracket (150) can press the lead (140). The center bracket (150) can extend in the Y direction. The center bracket (150) can overlap with the center beam (111CB). The center bracket (150) can be coupled to the second fixing members (133).

[0086] A first end of the center bracket (150) may be fixed to a first cross beam by first to third fixing devices (131, 133, 137), and a second end of the center bracket (150) may be fixed to a second cross beam by first to third fixing devices (131, 133, 137). The first and second cross beams may be included in the cross beams (130). The first and second cross beams may be spaced apart from each other with the center beam (111CB) interposed therebetween, and may overlap each other in the Y direction. The first cross beam may be interposed between the center beam (111CB) and the first side wall (112), and the second cross beam may be interposed between the center beam (111CB) and the second side wall (113).

[0087] The battery cell assemblies (120) adjacent to the first cross beam (i.e., spaced apart from each other with the first cross beam therebetween) are referred to as first and second battery cell assemblies, and the battery cell assemblies (120) adjacent to the second cross beam (i.e., spaced apart from each other with the second cross beam therebetween) are referred to as third and fourth battery cell assemblies.

[0088] According to exemplary embodiments, the center bracket (150) may be fixed by first fasteners (131) coupled to the cross beams (130), second fasteners (133) coupled to the first fasteners (131), and third fasteners (137) coupled to the second fasteners (133). Accordingly, the fasteners for fixing the center bracket (150) can be prevented (or alleviated, or minimized) from taking up an internal space of the battery pack (100), and the energy density (e.g., volume density) of the battery pack (100) can be increased.

[0089] The battery pack (100) may further include a plurality of exhaust devices. The plurality of exhaust devices may be coupled to, for example, the third side wall (115). The plurality of exhaust devices may be coupled to, for example, exhaust holes of the third side wall (115). Each of the plurality of exhaust devices may include a spring type or a rupture disk. Each of the plurality of exhaust devices may be configured to discharge gas within the battery pack (100) when the pressure within the battery pack (100) exceeds a threshold value.

[0090] The plurality of exhaust devices may be configured to delay thermal propagation by releasing high temperature gases inside the battery pack (100) to the outside when at least one of the plurality of battery cell assemblies (120) is in a thermal runway state.

[0091] Here, thermal runaway of multiple battery cell assemblies (120) is a state in which temperature changes of multiple battery cell assemblies (120) further accelerate the temperature change, which is an uncontrollable positive feedback. Multiple battery cell assemblies (120) in a state of thermal runaway exhibit a rapid temperature increase and emit a large amount of high-pressure gas and combustion debris.

[0092] The battery pack (100) may further include electrical components. The electrical components may be mounted on the lower frame (110). The electrical components may be positioned between the third side wall (113) where the exhaust devices are installed and the plurality of battery cell assemblies (120). The electrical components may include any electronic components necessary to operate the battery pack.

[0093] The electrical components may include, for example, a Battery Management System (BMS). The BMS may be configured to monitor, balance, and control the battery pack. Monitoring of the battery pack (100) may include measuring voltage and current of specific nodes within a plurality of battery cell assemblies (120) and measuring temperature of set locations within the battery pack (100). The battery pack (100) may include measuring instruments for measuring the voltage, current, and temperature described above.

[0094] Balancing of a battery pack (100) is an operation that reduces the deviation between multiple battery cell assemblies (120). Control of the battery pack (100) includes preventing overcharge, overdischarge, and overcurrent. Through monitoring, balancing, and control, the battery pack (100) can operate under optimal conditions, thereby preventing shortening of the lifespan of each of the multiple battery cell assemblies (120).

[0095] The electrical components may further include a cooling device, a PRA (Power Relay Assembly), a safety plug, etc. The cooling device may include a cooling fan. The cooling fan may prevent overheating of each of the plurality of battery cell assemblies (120) by circulating air inside the battery pack (100). The PRA may be configured to supply or cut off power from the high-voltage battery to an external load (e.g., a vehicle motor). The PRA may protect the plurality of battery cell assemblies (120) and the external load (e.g., a vehicle motor) by cutting off power supply to the external load (e.g., a vehicle motor) in a situation where an abnormal voltage, such as a voltage surge, occurs.

[0096] The battery pack (100) may further include a plurality of bus bars configured to electrically connect a plurality of battery cell assemblies (120). The plurality of battery cell assemblies (120) may be connected in series by the plurality of bus bars. Accordingly, the battery pack (100) may be configured to output a high voltage to an external load (e.g., a vehicle motor).

[0097]

[0098] The present invention has been described in more detail through drawings and examples. However, the configurations described in the drawings or examples described in this specification are merely embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

Claims

1. Lower frame including base plate and side walls; First to fourth battery cell assemblies arranged on the lower frame and including a plurality of battery cells; A first cross beam interposed between the first and second battery cell assemblies, wherein the first and second battery cells are spaced apart in a first direction; As a second cross beam interposed between the third and fourth battery cell assemblies, the third and fourth battery cell assemblies are spaced apart from the first and second battery cell assemblies in a second direction perpendicular to the first direction; First fixtures coupled to the first cross beam and spaced from the base plate; and A battery pack comprising second fasteners coupled to the first fasteners.

2. In paragraph 1, A battery pack further comprising leads coupled to the side walls.

3. In paragraph 2, A battery pack further comprising gaskets interposed between the second fixing members and the leads.

4. In paragraph 3, Each of the above second fixtures comprises a flange, The above flange includes a groove having a depth less than the height of each of the above gaskets, and A battery pack characterized in that the above gaskets are arranged in the grooves.

5. In paragraph 2, A battery pack further characterized by comprising a center bracket disposed on the lead.

6. In paragraph 5, A battery pack characterized in that the center bracket is coupled to the second fixing members.

7. In paragraph 5, A battery pack further comprising third fasteners coupled to the second fasteners and in contact with the center bracket.

8. In paragraph 5, The first end of the above center bracket is fixed to the first cross beam, and A battery pack, characterized in that the second end of the center bracket is fixed to the second cross beam.

9. In paragraph 5, A battery pack, characterized in that the above lead is fixed by the above center bracket.

10. In paragraph 5, Further comprising a center beam interposed between the first and second battery cell assemblies, A battery pack, characterized in that the center beam overlaps the center bracket.

11. In paragraph 10, A battery pack, wherein the center beam is perpendicular to the center bracket.

12. In paragraph 1, Each of the above second fixtures, 1st cylinder; A flange portion having a larger diameter than the first cylindrical portion; A hexagonal portion spaced apart from the first cylindrical portion with the flange portion interposed therebetween; and A battery pack characterized by including a second cylindrical portion spaced apart from the flange portion with the hexagonal portion therebetween.

13. In paragraph 12, A battery pack, characterized in that each of the second fixing members further includes an adhesive applied to the first cylindrical portion.

14. In paragraph 12, A battery pack, characterized in that each of the first cylindrical portions of the second fixing members is coupled to a corresponding one of the first fixing members.

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