Battery pack

Abstract

Exemplary embodiments provide a battery pack. The battery pack includes: a lower frame including a bottom plate and side walls; a first battery cell assembly, a second battery cell assembly, a third battery cell assembly, and a fourth battery cell assembly disposed on the lower frame and including a plurality of battery cells; a first cross beam interposed between the first battery cell assembly and the second battery cell assembly, in which the first battery cell and the second battery cell are spaced apart from each other in the first direction; a second cross beam interposed between the third battery cell assembly and the fourth battery cell assembly, in which the third battery cell assembly and the fourth battery cell assembly are spaced apart from the first battery cell assembly and the second battery cell assembly in a second direction perpendicular to the first direction; a first fixing portion coupled to the first cross beam and spaced apart from the bottom plate; and a second fixing portion coupled to the first fixing portion.

Description

TECHNICAL FIELD

[0001] The present application relates to a case and a battery pack including the same. This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0160157, filed on November 20, 2023, and the entire contents of which are incorporated herein by reference. BACKGROUND

[0002] Unlike primary batteries, secondary batteries can be charged and discharged multiple times. Secondary batteries have been widely used as an energy source for various types of wireless devices, such as handsets, notebook computers, and cordless vacuum cleaners. Recently, as the manufacturing cost per unit capacity of secondary batteries has been drastically reduced due to the improvement in energy density and economies of scale, and the mileage of battery electric vehicles (BEVs) has increased to the same level as that of fuel vehicles, the main use of secondary batteries has shifted from mobile devices to mobility.

[0003] The trend of the technical development of secondary batteries for mobility is to improve energy density and safety. The safety of secondary batteries for mobility is very important because it is closely related to the lives of passengers. The safety of secondary batteries can be achieved by mechanical strength, reliability of electrical insulation, and delay of heat transfer when a thermal runaway event occurs. SUMMARY

[0004] TECHNICAL PROBLEM

[0005] The present application relates to providing a battery pack having improved safety and energy density.

[0006] TECHNICAL SOLUTION

[0007] An exemplary embodiment of the present application provides a battery pack. The battery pack includes a lower frame including a bottom plate and a side wall; a first battery cell assembly, a second battery cell assembly, a third battery cell assembly, and a fourth battery cell assembly disposed on the lower frame and each including a plurality of battery cells; a first cross beam interposed between the first battery cell assembly and the second battery cell assembly, wherein the first battery cell and the second battery cell are spaced apart from each other in a first direction; a second cross beam interposed between the third battery cell assembly and the fourth battery cell assembly, wherein the third battery cell assembly and the fourth battery cell assembly are spaced apart from the first battery cell assembly and the second battery cell assembly in a second direction perpendicular to the first direction; a first fixing portion coupled to the first cross beam and spaced apart from the bottom plate; and a second fixing portion coupled to the first fixing portion.

[0008] The battery pack can further include a cover coupled to the side wall.

[0009] The battery pack can further include a gasket located between the second fixing portion and the cover.

[0010] Each of the second fixing parts can include a flange, the flange can include a groove having a depth less than a height of each of the washers, and the washers can be located in the groove.

[0011] The battery pack can further include a center bracket located on the cover.

[0012] The center bracket can be coupled to the second fixing parts.

[0013] The battery pack can further include a third fixing part coupled to the second fixing parts and in contact with the center bracket.

[0014] A first end of the center bracket can be fixed to the first cross beam, and a second end of the center bracket can be fixed to the second cross beam.

[0015] The cover can be fixed by the center bracket.

[0016] The battery pack can further include a center beam located between the first battery cell assembly and the second battery cell assembly.

[0017] The center beam can overlap the center bracket.

[0018] The center beam can be perpendicular to the center bracket.

[0019] Each of the second fixing parts can include a first cylindrical part, a flange having a diameter greater than a diameter of the first cylindrical part, a hexagonal part spaced apart from the first cylindrical part, the flange being located between the hexagonal part and the cylindrical part, and a second cylindrical part spaced apart from the flange, the hexagonal part being located between the second handle and the flange.

[0020] Each of the second fixing parts can further include an adhesive coated to the first cylindrical part.

[0021] The first cylindrical part of each of the second fixing parts can be coupled to a corresponding one of the first fixing parts.

[0022] Advantageous effects

[0023] According to the exemplary embodiments of the present application, an internal space of a battery pack occupied by fixing parts configured to fix a center bracket can be minimized. Accordingly, a battery pack having improved energy density can be provided.

[0024] Effects that can be achieved from the exemplary embodiments of the present application are not limited to what has been described above and other effects not described herein will become apparent from the following description when taken in conjunction with the accompanying drawings, or can be learned by practice of the exemplary embodiments of the present application. That is, non-intended effects which can be achieved from the exemplary embodiments of the present application will become apparent to those of ordinary skill in the art from the exemplary embodiments of the present application by systematic modification of the exemplary embodiments of the present application, or from the practice of the exemplary embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a flowchart of a method of manufacturing a battery pack according to an exemplary embodiment.

[0026] Figure 2 is a perspective view illustrating a method of manufacturing a battery pack according to an exemplary embodiment.

[0027] Figure 3 yes Figure 2 A partial enlarged perspective view of a part of.

[0028] Figure 4 It is along Figure 3 A cross-sectional view taken along line 3I-3I'.

[0029] Figure 5 It is along Figure 3 A cross-sectional view taken along line 3II-3II'.

[0030] Figure 6 is a perspective view illustrating a method of manufacturing a battery pack according to an exemplary embodiment.

[0031] Figure 7 yes Figure 6 A partial enlarged perspective view of a part of.

[0032] Figure 8 It is along Figure 7 A cross-sectional view taken along line 7I-7I'.

[0033] Figure 9 A second fixing portion is shown.

[0034] Figure 10 is a perspective view illustrating a method of manufacturing a battery pack according to an exemplary embodiment.

[0035] Figure 11 yes Figure 10 A partial enlarged perspective view of a part of.

[0036] Figure 12 It is along Figure 11 A cross-sectional view taken along line 11I-11I′.

[0037] Figure 13 is a perspective view illustrating a method of manufacturing a battery pack according to an exemplary embodiment.

[0038] Figure 14 yes Figure 13 An enlarged partial perspective view of a portion of a .

[0039] Figure 15 It is along Figure 14 A cross-sectional view taken along line 14I-14I′. DETAILED DESCRIPTION

[0040] Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings. Prior to describing the embodiments of the present application, the terms or words used in the specification and claims should not be interpreted as being limited to commonly used meanings or definitions but interpreted based on the meanings and concepts of the applicant that the inventor can appropriately define to best explain the principles of the present application in accordance with the technical concept of the present application.

[0041] Therefore, the embodiments set forth herein and the configurations shown in the drawings are merely examples of the present application and do not reflect all technical ideas of the present application, and it should be understood that various equivalents and modifications to the configurations have been made at the date of filing of the present application.

[0042] When it is determined that known configurations or functions related to the description of the present application will obscure the subject matter of the present application due to unnecessary details, detailed descriptions thereof will not be made.

[0043] Because the embodiments of the present application are provided in order to more fully explain the present application to those having ordinary skill in the art, the shapes, sizes, etc. of the components shown in the drawings can be exaggerated, omitted, or schematically shown for the sake of clarity. Therefore, it should not be understood that the sizes or ratios of the components completely reflect the actual sizes or ratios thereof.

[0044] (First Embodiment and Second Embodiment)

[0045] Figure 1 is a flowchart of a manufacturing method of a battery pack according to an exemplary embodiment.

[0046] Figure 2 is a perspective view showing a manufacturing method of a battery pack according to an exemplary embodiment.

[0047] Figure 3 is a partial perspective view of a portion POR2 of Figure 2

[0048] Figure 4 is a cross-sectional view taken along line 3I-3I' of Figure 3

[0049] Figure 5 is a cross-sectional view taken along line 3II-3II' of Figure 3

[0050] Figure 6 is a perspective view showing a manufacturing method of a battery pack according to an exemplary embodiment.

[0051] Figure 7 is a partial perspective view of a portion POR6 of Figure 6

[0052] ​​​​Figure 8 It is along Figure 7 A cross-sectional view taken along line 7I-7I'.

[0053] Figure 9 A second fixing portion is shown.

[0054] Figure 10 is a perspective view illustrating a method of manufacturing a battery pack according to an exemplary embodiment.

[0055] Figure 11 yes Figure 10 An enlarged partial perspective view of a portion of POR10.

[0056] Figure 12 It is along Figure 11 A cross-sectional view taken along line 11I-11I′.

[0057] Figure 13 is a perspective view illustrating a method of manufacturing a battery pack according to an exemplary embodiment.

[0058] Figure 14 yes Figure 13 An enlarged partial perspective view of a portion of POR13.

[0059] Figure 15 It is along Figure 14 A cross-sectional view taken along line 14I-14I′.

[0060] Reference Figures 1 to 5 In P110, the battery cell assembly can be set on the lower frame.

[0061] The lower frame 110 may provide a space for mounting a battery cell assembly 120 to be described below. The lower frame 110 may include a bottom plate 111 and first, second, third, and fourth sidewalls 112, 113, 114, and 115. A plurality of cross members 130 may be provided on the lower frame 110.

[0062] Two directions substantially parallel to the upper surface 111U of the bottom plate 111 are defined as the X-axis direction and the Y-axis direction, and a direction substantially perpendicular to the upper surface 111U of the bottom plate 111 is defined as the Z-axis direction. The X-axis direction, the Y-axis direction, and the Z-axis direction may be substantially perpendicular to each other. Unless otherwise specified, the definitions of the directions apply to the following figures.

[0063] The bottom plate 111 may include multiple plates. The multiple plates may be joined by, for example, friction stir welding. Each of the multiple plates may include a cooling channel, a cavity, and a rib. Each of the cooling channel, cavity, and rib may extend along the X-axis direction.

[0064] The cooling channels can provide paths that allow a cooling fluid to flow therethrough. The cooling channels can be spaced apart from each other in the Y-axis direction. The cooling channels can be arranged along the Y-axis direction. The cavities are empty spaces inside the plurality of plates. Due to the formation of the cavities, the mass of the plurality of plates can be reduced, the energy density of the battery pack 100 including the lower frame 110 can be improved Figure 13 The ribs can define the cooling channels and the cavities. The ribs can surround the cooling channels and the cavities. The ribs can maintain the airtightness of the cooling channels and the cavities.

[0065] The center plate of the plurality of plates can include a center beam 111CB. The center beam 111CB can protrude from the upper surface 111U of the bottom plate 111. The center beam 111CB can extend in the X-axis direction.

[0066] The first side wall 112 and the second side wall 113 can be coupled to the bottom plate 111. The first side wall 112 and the second side wall 113 can be spaced apart from each other in the Y-axis direction with the bottom plate 111 interposed therebetween. Each of the first side wall 112 and the second side wall 113 can include a plate portion that is coplanar with the bottom plate 111, a wall portion that is perpendicular to the plate portion, and a wing portion that is outside the wall portion. The wall portion of each of the first side wall 112 and the second side wall 113 can be substantially perpendicular to the Y-axis direction. The wing portion of each of the first side wall 112 and the second side wall 113 can include a plurality of coupling holes. The wing portion of each of the first side wall 112 and the second side wall 113 can 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).

[0067] The third side wall 114 and the fourth side wall 115 can be coupled to the bottom plate 111. The third side wall 114 and the fourth side wall 115 can be located on the bottom plate 111. The third side wall 114 and the fourth side wall 115 can be spaced apart from each other in the X-axis direction. The third side wall 114 and the fourth side wall 115 can be substantially perpendicular to the X-axis direction. The third side wall 114 can include a plurality of exhaust holes for mounting an exhaust device.

[0068] The plurality of battery cell assemblies 120 can be located on the bottom plate 111 of the lower frame 110. The bottom plate 111 can support the plurality of battery cell assemblies 120. The first side wall 112, the second side wall 113, the third side wall 114, and the fourth side wall 115 can horizontally surround the plurality of battery cell assemblies 120. The first side wall 112, the second side wall 113, the third side wall 114, and the fourth side wall 115 can protect the plurality of battery cell assemblies 120.

[0069] According to an exemplary embodiment, Figure 13The battery pack 100 can be a module-free type, and each of the plurality of battery cell assemblies 120 can not include a module frame. Each of the plurality of battery cell assemblies 120 can include a battery cell stack 121 and a top cover 127.

[0070] The battery cell stack 121 can include a plurality of battery cell banks connected in series to each other. Each of the plurality of battery cell banks can include one or more battery cells connected in parallel. The number of battery cell banks connected in series and the number of battery cells connected in parallel can be determined according to the voltage and current to be output from each of the plurality of battery cell assemblies 120.

[0071] A battery cell is a basic unit of a lithium ion battery (i.e., a secondary battery). Each battery cell includes an electrode assembly, an electrolyte, and a case. Each battery cell can be a cylindrical battery cell, a square battery cell, or a pouch-type battery cell. The electrode assembly of the cylindrical battery cell is built in a cylindrical metal can. The electrode assembly of the square battery cell is built in a square metal can. The electrode assembly of the pouch-type battery cell is built in a soft pack case including an aluminum laminate sheet.

[0072] The electrode assembly can include a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode. The electrode assembly can be a jelly-roll type electrode assembly or a stacked type electrode assembly. The jelly-roll type electrode assembly can include a structure in which a positive electrode, a negative electrode, and a separator therebetween are wound together. The stacked type electrode assembly can include a plurality of positive electrodes and a plurality of negative electrodes stacked in sequence and a plurality of separators therebetween.

[0073] According to an exemplary embodiment, the battery cell stack 121 can further include a plurality of separators. The plurality of separators can horizontally support the plurality of battery cells to prevent swelling of the plurality of battery cells. According to an exemplary embodiment, the plurality of separators can be thermal barriers. According to an exemplary embodiment, each of the plurality of separators can have a high melting temperature and a low thermal conductivity. According to an exemplary embodiment, each of the plurality of separators can include a fire-retardant material, such as ceramic and coated glass material. According to an exemplary embodiment, the plurality of separators can be configured to release a fire-retardant material and a fire extinguishing agent when a thermal runaway event occurs.

[0074] The top cover 127 can be located on the battery cell stack 121. The top cover 127 can include, for example, an insulating material. The top cover 127 can cover the battery cell stack 121.

[0075] The cross beam 130 can isolate the plurality of battery cell assemblies 120 from each other. The cross beam 130 can be interposed between the plurality of battery cell assemblies 120. The plurality of battery cell assemblies 120 can be spaced apart from each other in the X-axis direction with the cross beam 130 interposed therebetween. The cross beam 130 can extend in the Y-axis direction.

[0076] Each cross beam 130 can include a plurality of openings 130OP. The first fixing portion 131 can be coupled to the plurality of openings 130OP. Each first fixing portion 131 can include a flange 131F and a modified flange 131DF. Each first fixing portion 131 can be a blind nut. Each first fixing portion 131 can be coupled to a corresponding one of the cross beams 130. Each first fixing portion 131 can be partially embedded in the corresponding one of the cross beams 130. The modified flange 131DF can be formed in a process of coupling each first fixing portion 131 to the rib of the corresponding one of the cross beams 130. The plurality of battery cell assemblies 120 can be arranged along the X-axis direction and the Y-axis direction. In Figure 1 In P120, the number of the battery cell assemblies 120 arranged along the X-axis direction is three, and the number of the battery cell assemblies 120 arranged along the Y-axis direction is two. Thus, the array of the plurality of battery cell assemblies 120 can be a 3x2 array. Based on the above description, one of ordinary skill in the art will be able to easily obtain the plurality of battery cell assemblies 120 arranged in an MxN array (here, M and N are each an integer of 2 or more).

[0077] The center beam 111CB can space the plurality of battery cell assemblies 120 in the Y-axis 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. A portion of the cross beams 130 can be spaced apart from the other portion of the cross beams 130 in the Y-axis direction, with the center beam 111CB interposed therebetween.

[0078] Next, reference is made to Figure 1 and Figures 6 to 9 In P120, the second fixing portion 133 can be coupled to the first fixing portion 131.

[0079] The second fixing portion 133 can be, for example, a bidirectional bolt. Each second fixing portion 133 can include a first cylindrical portion 133S1, a flange 133F, a hexagonal portion 133H, and a second cylindrical portion 133S2.

[0080] The first cylindrical portion 133S1 can have a substantially cylindrical shape. Each second fixing portion 133 can further include an adhesive 133A applied to the first cylindrical portion 133S1.

[0081] The flange 133F can have a substantially disc shape. The diameter of the flange 133F can be greater than the diameter of the first cylindrical portion 133S1. The flange 133F can be connected to the first cylindrical portion 133S1. The flange 133F can include a groove 133G. A corresponding one of the washers 135 can be seated in the groove 133G of the flange 133F of each second fixing portion 133. The height of each washer 135 can be greater than the depth of the groove 133G.

[0082] The hexagonal portion 133H can have a shape of a substantially hexagonal column. The hexagonal portion 133H can be connected to the flange 133F. The hexagonal portion 133H can be spaced apart from the first cylindrical portion 133S1 with the flange 133F interposed therebetween.

[0083] The second cylindrical portion 133S2 can have a shape of a substantially cylindrical column. The second cylindrical portion 133S2 can have a diameter smaller than that of the flange 133F. The second cylindrical portion 133S2 can be connected to the hexagonal portion 133H. The second cylindrical portion 133S2 can be spaced apart from the flange 133F with the hexagonal portion 133H interposed therebetween.

[0084] Next, referring to Figure 1 and Figures 10 to 12 In P130, the cover 140 can be provided. The cover 140 can be coupled to the lower frame 110. The cover 140 can be coupled to the first side wall 112, the second side wall 113, the third side wall 114, and the fourth side wall 115 of the lower frame 110. The gasket 135 can be interposed between the flange 133F of a corresponding one of the second fixing portions 133 and the cover 140. Accordingly, the gasket 135 can be pressed by the cover 140, and thus a liquid-tight seal can be provided to an internal space defined by the cover 140 and the lower frame 110.

[0085] Thereafter, referring to Figure 1 and Figures 13 to 15 In P140, the center bracket 150 can be provided. The center bracket 150 can be fixed by the second fixing portion 133 and the third fixing portion 137. The center bracket 150 can be in contact with a corresponding one of the second fixing portion 133 and the third fixing portion 137. The center bracket 150 can include a portion interposed between the second fixing portion 133 and the third fixing portion 137.

[0086] The battery pack 100 can be provided by providing the center bracket 150 and coupling the same to the cover 140. The battery pack 100 can include the lower frame 110, the plurality of battery cell assemblies 120, the first fixing portion 131, the second fixing portion 133, the third fixing portion 137, the gasket 135, the cover 140, and the center bracket 150.

[0087] The center bracket 150 can be located on the cover 140. The center bracket 150 can be in contact with the cover 140. The center bracket 150 can fix the cover 140. The center bracket 150 can press the cover 140. The center bracket 150 can extend in the Y-axis direction. The center bracket 150 can overlap the center beam 111CB. The center bracket 150 can be coupled to the second fixing portion 133.

[0088] The first end of the center bracket 150 can be fixed to the first cross beam via the first fixing part 131, the second fixing part 133, and the third fixing part 137, and the second end thereof can be fixed to the second cross beam via the first fixing part 131, the second fixing part 133, and the third fixing part 137. The first cross beam and the second cross beam can be included in the cross beam 130. The first cross beam and the second cross beam can be spaced apart from each other across the center beam 111CB and overlap each other in the Y-axis direction. The first cross beam can be interposed between the center beam 111CB and the first side wall 112, and the second cross beam can be interposed between the center beam 111CB and the second side wall 113.

[0089] The battery cell assemblies 120 adjacent to (i.e., spaced apart from each other across) the first cross beam will be referred to as the first and second battery cell assemblies, and the battery cell assemblies 120 adjacent to (i.e., spaced apart from each other across) the second cross beam will be referred to as the third and fourth battery cell assemblies.

[0090] According to an exemplary embodiment, the center bracket 150 can be fixed by the first fixing part 131 coupled to the cross beam 130, the second fixing part 133 coupled to the first fixing part 131, and the third fixing part 137 coupled to the second fixing part 133. Accordingly, it can be possible to prevent (or alleviate or minimize) the fixing parts for fixing the center bracket 150 from occupying the internal space of the battery pack 100, and it can be possible to improve the energy density (e.g., volumetric density) of the battery pack 100.

[0091] The battery pack 100 can further include a plurality of exhaust devices. The plurality of exhaust devices can be coupled to, for example, the third side wall 115. The plurality of exhaust devices can be coupled to, for example, the exhaust hole of the third side wall 115. Each of the plurality of exhaust devices can include a spring type or a rupture disc. Each of the plurality of exhaust devices can be configured to discharge gas from the inside of the battery pack 100 to the outside when the internal pressure of the battery pack 100 exceeds a threshold value.

[0092] The plurality of exhaust devices can be configured to delay the spread of heat by discharging high-temperature gas from the inside of the battery pack 100 to the outside when at least one of the plurality of battery cell assemblies 120 is in a thermal runaway state.

[0093] Here, the thermal runaway state of the plurality of battery cell assemblies 120 is a state in which the temperature change of the plurality of battery cell assemblies 120 accelerates the temperature change thereof (i.e., uncontrollable positive feedback). The temperature of the plurality of battery cell assemblies 120 in the thermal runaway state sharply increases, and a large amount of high-pressure gas and combustion debris is discharged.

[0094] The battery pack 100 can further include electrical components. The electrical components can be mounted in the lower frame 110. The electrical components can be disposed between the third side wall 113 on which the exhaust device is mounted and the plurality of battery cell assemblies 120. The electrical components can include electronic devices required to drive the battery pack.

[0095] The electrical components can include, for example, a battery management system (BMS). The BMS can be configured to monitor, balance, and control the battery pack 100. The monitoring of the battery pack 100 can include measuring the voltage and current of certain nodes among the plurality of battery cell assemblies 120 and measuring the temperature at a set position in the battery pack 100. The battery pack 100 can include a measurement device for measuring the voltage, current, and temperature as described above.

[0096] The balancing of the battery pack 100 is an operation to reduce the deviation between the plurality of battery cell assemblies 120. The control of the battery pack 100 includes preventing overcharging, overdischarging, and overcurrent. Through the monitoring, balancing, and control, the battery pack 100 can be operated in optimal conditions, thereby preventing the service life of each of the plurality of battery cell assemblies 120 from being shortened.

[0097] The electrical components can further include a cooling device, a power relay assembly (PRA), safety, etc. The cooling device can include a cooling fan. The cooling fan can circulate air in the battery pack 100 to prevent each of the plurality of battery cell assemblies 120 from overheating. The PRA can be configured to supply or cut off power from the high-voltage battery to an external load (e.g., a motor of a vehicle). When an abnormal voltage such as a voltage surge occurs, the PRA can cut off the power supply to the external load (e.g., a motor of a vehicle) to protect the plurality of battery cell assemblies 120 and the external load.

[0098] The battery pack 100 can further include a plurality of busbars configured to electrically connect the plurality of battery cell assemblies 120. The plurality of battery cell assemblies 120 can be connected in series through the plurality of busbars. Accordingly, the battery pack 100 can be configured to output a high voltage to an external load (e.g., a motor of a vehicle).

[0099] The present application has been described above in greater detail with reference to the accompanying drawings and embodiments, etc. However, the configuration shown in the drawings or embodiments described in the specification is only an embodiment of the present application and does not reflect all technical ideas of the present application, and thus it should be understood that various equivalents and modifications to the configuration have been made on the date of filing of the present application.

Claims

1. A battery pack comprising: a lower frame, including a bottom plate and side walls; a first battery cell assembly, a second battery cell assembly, a third battery cell assembly, and a fourth battery cell assembly, disposed on the lower frame and each including a plurality of battery cells; a first crossbeam interposed between the first battery cell assembly and the second battery cell assembly, wherein the first battery cell and the second battery cell are spaced apart from each other in a first direction; a second crossbeam interposed between the third battery cell assembly and the fourth battery cell assembly, wherein the third battery cell assembly and the fourth battery cell assembly are spaced apart from the first battery cell assembly and the second battery cell assembly in a second direction perpendicular to the first direction; a first fixing portion coupled to the first beam and spaced apart from the bottom plate; and The second fixing portion is coupled to the first fixing portion. 2 . The battery pack according to claim 1 , further comprising a lead coupled to the side wall. 3 . The battery pack according to claim 2 , further comprising a gasket located between the second fixing portion and the cover.

4. The battery pack according to claim 3, wherein: Each of the second fixing portions includes a flange, wherein the flange includes a groove having a depth less than the height of each of the washers, and The gasket is located in the groove.

5. The battery pack of claim 2, further comprising a center support located on the cover.

6. The battery pack according to claim 5, wherein: The center bracket is coupled to the second fixing portion. 7 . The battery pack according to claim 5 , further comprising a third fixing portion coupled to the second fixing portion and in contact with the center bracket.

8. The battery pack according to claim 5, wherein: The first end of the central support is fixed to the first crossbeam, and The second end portion of the central support is fixed on the second crossbeam.

9. The battery pack according to claim 5, wherein: The cover is fixed by the central support.

10. The battery pack according to claim 5, further comprising a center beam located between the first battery cell assembly and the second battery cell assembly, in, The center beam overlaps with the center support.

11. The battery pack according to claim 10, wherein: The central beam is perpendicular to the central support.

12. The battery pack according to claim 1, wherein: Each of the second fixing portions includes: a first cylindrical portion; a flange, wherein the diameter of the flange is larger than the diameter of the first cylindrical portion; a hexagonal portion spaced apart from the first cylindrical portion, the flange being located between the hexagonal portion and the cylindrical portion; and The second cylindrical portion is spaced apart from the flange, and the hexagonal portion is located between the second cylindrical portion and the flange.

13. The battery pack according to claim 12, wherein: Each of the second fixing portions further includes an adhesive applied to the first cylindrical portion.

14. The battery pack according to claim 12, wherein: The first cylindrical portion of each of the second fixing portions is coupled to a corresponding one of the first fixing portions.

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