Secondary Battery Module

Abstract

To provide a rechargeable battery module for smoothly opening a vent in an emergency and preventing a chain explosion of peripheral battery cells.SOLUTION: A rechargeable battery module includes: a plurality of battery cells including a vent hole; a first holder for receiving one of sides of the battery cells and supporting the same; a second holder receiving other sides of the battery cells and supporting the same, and combined to the first holder; a first plate installed on one side of the second holder and including an outlet group composed of a plurality of outlets at positions corresponding to the respective vent holes of the battery cells; and a second plate disposed on one side of the first plate and continuing from the vent hole and the outlet group to intercept a discharge discharged.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a secondary battery module, and more particularly to a secondary battery module that smoothly opens a vent in an emergency to prevent a chain reaction explosion of surrounding battery cells. [Background technology]

[0002] Unlike primary batteries, rechargeable batteries are batteries that can be repeatedly charged and discharged. Small-capacity secondary batteries are used in small, portable electronic devices such as mobile phones, laptops, and camcorders. Large-capacity and high-density secondary batteries are used as power sources for driving motors in hybrid and electric vehicles and for energy storage.

[0003] A secondary battery includes an electrode assembly that charges and discharges current, a case that contains the electrode assembly and an electrolyte, and electrode terminals that are connected to the electrode assembly and extend to the outside of the case. The electrode assembly can be formed into a jelly roll type that is formed by winding up electrodes and a separator.

[0004] Electric vehicles and energy storage devices require large-capacity secondary battery modules, which are comprised of multiple battery cells. If a fire or explosion occurs in one battery cell of the module, the flames and high-temperature gases emitted from that battery cell may spread to other adjacent battery cells, causing a chain reaction explosion.

[0005] Technology is needed to prevent this. One example is potting technology, which covers the positive electrode of a battery cell with foamed urethane or silicone material. The potting material protects the battery cell from air and moisture under normal conditions, and in the event of an emergency such as thermal runaway, the foamed voids open, allowing vent gas and debris from the battery cell to be smoothly released, preventing the escaped debris from transferring to surrounding battery cells and preventing chain explosions.

[0006] Potting is expensive and difficult to manage, which increases the processing costs of secondary battery modules. In cylindrical batteries, the potting material can seep into the cap assembly, preventing the battery cell from venting, which can lead to side ruptures. Summary of the Invention [Problem to be solved by the invention]

[0007] An embodiment of the present invention provides a secondary battery module that prevents a chain reaction explosion of neighboring battery cells by smoothly opening a vent in an emergency. [Means for solving the problem]

[0008] A secondary battery module according to one embodiment of the present invention includes a plurality of battery cells each having a vent hole; a first holder that accommodates and supports one side (lower part) of the battery cells; a second holder that accommodates and supports the other side (upper part) of the battery cells and is connected to the first holder; first plates that are provided on one side (upper part) of the second holder and have exhaust port groups each formed of a plurality of exhaust ports at positions corresponding to the vent holes of each of the battery cells; and a second plate that is disposed on one side (upper part) of the first plate and is connected to the vent holes and the exhaust port group to block exhaust from being discharged.

[0009] The battery cells can be formed from cylindrical secondary batteries.

[0010] The outlet may have a first width in a diameter direction and a first length in a circumferential direction, and the outlet group may include a plurality of the outlets and may have a first spacing in the circumferential direction.

[0011] The group of outlets defines an overall area (A1-A2) by an outer first diameter (D1) and an inner second diameter (D2), and the overall area (A1-A2) includes an open area (A3*N) formed by the plurality of first outlets and a closed area (A4*N) formed between the plurality of first outlets, and the ratio of the closed area (A4*N) to the overall area (A1-A2) can be set to be greater than 10.78% and less than 31.3%.

[0012] The ratio (A4*N) of the closed area to the total area (A1-A2) can be set to be greater than 10.78% and less than or equal to 15.4%. The ratio (A4*N) of the closed area to the total area (A1-A2) can further be set to be greater than 15.4% and less than 31.3%.

[0013] The group of exhaust ports may include a plurality of first exhaust ports corresponding to the vent holes and a plurality of second exhaust ports provided on an outer periphery of the first exhaust ports.

[0014] The first outlets may have a first width in a diametrical direction and a first length in a circumferential direction, the first outlets having a first spacing in the circumferential direction, the second outlets may have a second width in a diametrical direction and a second length in a circumferential direction, and the second outlets may have a second spacing in the circumferential direction.

[0015] The first outlet defines a first overall area (A1-A2) by a first outer diameter (D1) and a second inner diameter (D2), and the first overall area (A1-A2) includes an open area (A3*N) formed by the plurality of first outlets and a first closed area (A4*N) formed between the plurality of first outlets. The second outlet defines a second overall area (A21-A22) by a first outer diameter (D21) and a second inner diameter (D22), and the second overall area (A21-A22) includes an open area (A23*N) formed by the plurality of second outlets and a second closed area (A24*N) formed between the plurality of second outlets. A ratio of the sum of the first closed area (A4*N) and the second closed area (A24*N) to the sum of the first overall area (A1-A2) and the second overall area (A21-A22) may be set to be greater than 10.78% and less than 31.3%.

[0016] The ratio of the sum of the first closed area (A4*N) and the second closed area (A24*N) to the sum of the first total area (A1-A2) and the second total area (A21-A22) may be set to be greater than 10.78% and less than or equal to 15.4%. The ratio of the sum of the first closed area (A4*N) and the second closed area (A24*N) to the sum of the first total area (A1-A2) and the second total area (A21-A22) may be set to be greater than 15.4% and less than 31.3%. [Effects of the Invention]

[0017] In one embodiment of the present invention, a group of exhaust ports is formed on the first plate, and each exhaust port corresponds to a vent hole of each battery cell. In the event of an emergency, the exhaust ports open smoothly, and explosion pressure, flames, and debris are discharged to the outside of the first plate, preventing chain reactions of explosions of neighboring battery cells inside the first plate. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is an exploded perspective view of a secondary battery module according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a cross-sectional perspective view of a cylindrical battery cell applied to FIG. 1. [Figure 4] FIG. 2 is a partial plan view of a first plate applied to FIG. 1. [Figure 5] FIG. 3 is a plan view showing the relationship between the vent holes of the battery cells and the exhaust ports of the first plate in FIGS. 1 and 2. [Figure 6] FIG. 10 is a partial plan view of a first plate applied to a secondary battery module according to a second embodiment of the present invention. [Figure 7] FIG. 7 is a plan view showing the relationship between the vent holes of the battery cells and the exhaust ports of the first plate in FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. In the drawings, parts unnecessary for the explanation are omitted in order to clearly explain the present invention, and the same reference numerals are used throughout the specification to refer to the same or similar components.

[0020] Fig. 1 is an exploded perspective view of a secondary battery module according to a first embodiment of the present invention, and Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. Referring to Figs. 1 and 2, a secondary battery module 100 according to the first embodiment includes a plurality of battery cells 30, a first holder 11, a second holder 12, a first plate 21, and a second plate 22. In one embodiment, the battery cells 30 may be formed of cylindrical secondary batteries having vent holes 31.

[0021] Figure 3 is a cross-sectional perspective view of the cylindrical battery cell shown in Figure 1. Referring to Figure 3, the cylindrical battery cell 30 includes an electrode assembly 32 that charges and discharges, a case 33 that houses the electrode assembly 32, and a cap assembly 34 that is electrically connected to the electrode assembly 32 and is insulatedly coupled to the opening of the case 33. A cap plate 35 that forms the cap assembly 34 has a vent hole 31 that allows exhaust to be discharged through the vent hole 31 when a vent 36 is cut. The exhaust includes vent gas, explosion pressure, flames, and debris.

[0022] 1 and 2, the first holder 11 has a plurality of first receiving portions 111 to receive and support the lower portion of one side of the battery cells 30. The second holder 12 has a plurality of second receiving portions 121 to receive and support the upper portion of the other side of the battery cells 30. The second holder 12 is coupled to the first holder 11 to receive the battery cells 30 in the first and second receiving portions 111 and 121.

[0023] For example, the first holder 11 has a first protrusion 113 to support one lower side of the battery cell 30, and the second holder 12 has a second protrusion 123 to support the other upper side of the battery cell 30. The first and second protrusions 113 and 123 prevent the battery cell 30 from separating from the first and second holders 11 and 12 in the vertical direction in the drawing.

[0024] The first plate 21 is provided on one side of the upper portion of the second holder 12 and includes a group of exhaust ports 40 each formed of a plurality of exhaust ports 41 at positions corresponding to the vent holes 31 of each battery cell 30. As an example, the first plate 21 may be formed by plastic injection molding.

[0025] The second plate 22 is disposed on one side of the first plate 21 and is connected to the vent hole 31 and the exhaust port 41 of the exhaust port group 40, and blocks the exhaust discharged through the vent hole 31. That is, the second plate 22 blocks the vent gas, explosion pressure, flames, and debris discharged through the vent hole 31.

[0026] For this reason, a gap (G) is formed between the first and second plates 21 and 22 in the vertical direction. The space between the first and second plates 21 and 22 due to the gap (G) buffers the explosion pressure, dissipates the heat of the flame, and blocks debris to prevent it from scattering outside the secondary battery module 100.

[0027] 4 is a partial plan view of the first plate applied to FIG. 1, and FIG. 5 is a plan view showing the relationship of the exhaust ports of the first plate to the vent holes of the battery cells in FIGS. 1 and 2. In FIG.

[0028] 1 to 5, in the outlet group 40 of the first plate 21, the outlets 41 have a first width (W1) in the diameter direction and a first length (L1) in the circumferential direction. The first length (L1) refers to a curved length set at the middle of the first width (W1). The outlet group 40 has a plurality of outlets 41 and has a first interval (G1) in the circumferential direction. The first interval (G1) refers to a curved length set between two adjacent outlets 41 at the middle of the first width (W1).

[0029] A plurality of exhaust ports 41 are formed in the exhaust port group 40, and adjacent exhaust ports 41 may be set at an angle (θ) of 15° to 60° based on the center of the first length (L1). As an example, eight exhaust ports 41 are formed in the exhaust port group 40, and two adjacent exhaust ports 41 are set at an angle (θ) of 45° based on the center of the first length (L1). The number of exhaust ports 41 determines the blocking performance of the discharged explosion pressure, flame, and debris. When the number of exhaust ports 41 is set, the first width (W1), first length (L1), and first interval (G1) of the exhaust ports 41 determine the blocking performance of the discharged explosion pressure, flame, and debris.

[0030] The outlet group 40 has a first outer diameter (D1) and a second inner diameter (D2) that define a total area (A1-A2). That is, the first diameter (D1) defines a first area (A1), and the second diameter (D2) defines a second area (A2). Therefore, the total area (A1-A2) of the outlet group 40 is calculated by subtracting the second area (A2) from the first area (A1).

[0031] In the first embodiment, the total area (A1-A2) of the outlet group 40 includes an open area (A3*N) due to the plurality of outlets 41 and a closed area (A4*N) between the plurality of outlets 41. The open area (A3*N) is set to A3*8, and the closed area (A4*N) is set to A4*8. The area ratio ((A4*N) / (A1-A2)) of the closed area (A4*N) to the total area (A1-A2) of the outlet group 40 is set to be greater than 10.78% and less than 31.3%.

[0032] If the area ratio ((A4*N) / (A1-A2)) is less than 10.78%, molding becomes difficult during injection. If the area ratio ((A4*N) / (A1-A2)) is greater than 10.78% and less than 15.4%, injection molding becomes possible, and the exhaust port 41 operates normally due to the explosion pressure, flames, and debris released from the vent hole 31 of the battery cell 30. Therefore, only the entire area (A1-A2) of the exhaust port group 40, which is made up of multiple exhaust ports 41, is ruptured, and the exhaust port group 40 on the first plate 21 where the healthy battery cells 30 that did not explode are located remains normal. This allows the exhaust ports 41 to open smoothly in the event of an emergency, preventing chain reactions of explosions of surrounding battery cells 30.

[0033] In addition, the area ratio ((A4*N) / (A1-A2)) of the closed area (A4*N) to the total area (A1-A2) of the exhaust port group 40 can be set to be greater than 15.4% and less than 31.3%. When the area ratio ((A4*N) / (A1-A2)) is greater than 15.4% and less than 31.3%, the exhaust port 41 operates normally due to the explosion pressure, flames, and debris released from the vent hole 31 of the corresponding battery cell 30. Therefore, only the total area (A1-A2) of the exhaust port group 40, which is made up of multiple exhaust ports 41, is broken, and the exhaust port group 40 on the first plate 21 where the healthy battery cells 30 that did not explode are located can remain normal. This allows the exhaust ports 41 to open smoothly in the event of an emergency, preventing chain explosions of surrounding battery cells 30.

[0034] However, if the area ratio ((A4*N) / (A1-A2)) of the closed area (A4*N) to the total area (A1-A2) of the exhaust port group 40 is 31.3% or more, the total area (A1-A2) of the exhaust port group 40 may not function properly due to the discharged explosion pressure, flames, and debris, and the first plate 21 may be completely torn.

[0035] The second embodiment of the present invention will be described below. Explanations of the same parts as in the first embodiment will be omitted, and only the different parts will be described.

[0036] FIG. 6 is a partial plan view of a first plate applied to a secondary battery module according to a second embodiment of the present invention, and FIG. 7 is a plan view showing the relationship of the exhaust port of the first plate to the vent holes of the battery cells in FIG.

[0037] 6 and 7, in the secondary battery module 200 of the second embodiment, the first plate 221 is provided on one side of the upper portion of the second holder 12 and has a plurality of exhaust port groups 240 formed of a plurality of first exhaust ports 241 and second exhaust ports 242 at positions corresponding to the vent holes 31 of each battery cell 30.

[0038] That is, the outlet group 240 includes a plurality of first outlets 241 corresponding to the vent holes 31 and a plurality of second outlets 242 provided on the outer periphery of the first outlets 241. For example, the first outlets 241 are provided on the inner side in the diameter direction, and the second outlets 242 are provided on the outer side in the diameter direction.

[0039] The first outlets 241 have a first width (W1) in the radial direction and a first length (L1) in the circumferential direction. The first length (L1) refers to a curved length set at the middle of the first width (W1). The first outlets 241 have a first spacing (G1) in the circumferential direction. The first spacing (G1) refers to a curved length set between two adjacent first outlets 241 at the middle of the first width (W1).

[0040] For example, eight first exhaust ports 241 are formed, and two adjacent first exhaust ports 241 are set at a 45° angle (θ) based on the center of the first length (L1). The first exhaust ports 241 are responsible for blocking a portion of the discharged explosion pressure, flames, and debris depending on the number of first exhaust ports 241. When the number of first exhaust ports 241 is set, the first exhaust ports 241 are responsible for blocking a portion of the discharged explosion pressure, flames, and debris depending on the first width (W1), first length (L1), and first interval (G1) of the first exhaust ports 241.

[0041] The second outlets 242 have a second width (W2) in the radial direction and a second length (L2) in the circumferential direction. The second length (L2) refers to a curved length established at the middle of the second width (W2). The second outlets 242 have a second spacing (G2) in the circumferential direction. The second spacing (G2) refers to a curved length established between two adjacent second outlets 242 at the middle of the second width (W2).

[0042] A plurality of second exhaust ports 242 may be formed, and adjacent second exhaust ports 242 may be set at an angle (θ2) of 90° to 180° based on the center of the second length (L2). For example, two second exhaust ports 242 may be formed, and adjacent two second exhaust ports 242 may be set at an angle (θ2) of 180° based on the center of the second length (L2). The number of second exhaust ports 242 determines the blocking performance of the remaining portions of the discharged explosion pressure, flame, and debris. When the number of second exhaust ports 242 is set, the second width (W2), second length (L2), and second interval (G2) of the second exhaust ports 242 determine the blocking performance of the remaining portions of the discharged explosion pressure, flame, and debris.

[0043] Like the outlet group 40 of the first embodiment, the first outlet 241 defines a first overall area (A1-A2) by a first outer diameter (D1) and a second inner diameter (D2). That is, the first diameter (D1) defines the first area (A1), and the second diameter (D2) defines the second area (A2). Therefore, the overall area (A1-A2) in the first outlet 241 region of the outlet group 240 is calculated by subtracting the second area (A2) from the first area (A1).

[0044] In the first outlet 241 region of the second embodiment, the first total area (A1-A2) includes an open area (A3*N) due to the plurality of first outlets 241 and a first closed area (A4*N) between the plurality of first outlets 241.

[0045] The second outlet 242 defines a second overall area (A21-A22) by an outer diameter (D21) and an inner diameter (D22). That is, the diameter (D21) defines the first area (A21), and the diameter (D22) defines the second area (A22). Therefore, the overall area (A21-A22) of the second outlet 242 region of the outlet group 240 is calculated by subtracting the second area (A22) from the first area (A21).

[0046] In the second outlet 242 region, the second total area (A21-A22) includes an open area (A23*N) formed by the plurality of second outlets 242 and a second closed area (A24*N) formed between the plurality of second outlets 242.

[0047] In the outlet group 240, the ratio of the total area of ​​the first closed area (A4*N) and the second closed area (A24*N) to the total area of ​​the first overall area (A1-A2) and the second overall area (A21-A22), i.e., the area ratio of the closed area ((A4*N)+(A24*N)) to the total area ((A1-A2)+(A21-A22)), (((A4*N)+(A24*N)) / ((A1-A2)+(A21-A22))) is set to be greater than 10.78% and less than 31.3%.

[0048] If the area ratio (((A4*N)+(A24*N)) / ((A1-A2)+(A21-A22))) is less than 10.78%, molding becomes difficult during injection molding. If the area ratio (((A4*N)+(A24*N)) / ((A1-A2)+(A21-A22))) is greater than 10.78% and less than 15.4%, injection molding becomes possible, and the first exhaust port 241 and the second exhaust port 242 operate normally due to the explosion pressure, flames, and debris discharged from the vent hole 31 of the battery cell 30. Therefore, only the first and second overall areas (A1-A2, A21-A22) of the outlet group 240, which is defined by the plurality of first outlets 241 and second outlets 242, are broken, and the outlet group 240 on the first plate 21 where the normal battery cells 30 that did not explode are located remains in a normal state. As a result, in the event of an emergency, the first outlets 241 and the second outlets 242 can be smoothly opened, preventing a chain reaction explosion of the surrounding battery cells 30.

[0049] In addition, the area ratio (((A4*N)+(A24*N)) / ((A1-A2)+(A21-A22))) of the exhaust port group 240 can be set to be greater than 15.4% and less than 31.3%. When the area ratio (((A4*N)+(A24*N)) / ((A1-A2)+(A21-A22)))) is greater than 15.4% and less than 31.3%, the first exhaust port 241 and the second exhaust port 242 operate normally due to the explosion pressure, flames, and debris discharged from the vent hole 31 of the corresponding battery cell 30. Therefore, only the first and second overall areas (A1-A2, A21-A22) of the outlet group 240, which is defined by the plurality of first outlets 241 and second outlets 242, are broken, and the outlet group 240 on the first plate 21 where the normal battery cells 30 that did not explode are located remains in a normal state. As a result, in the event of an emergency, the first outlets 241 and the second outlets 242 can be smoothly opened, preventing a chain reaction explosion of the surrounding battery cells 30.

[0050] However, if the area ratio of the exhaust port group 240 (((A4*N)+(A24*N)) / ((A1-A2)+(A21-A22))) is 31.3% or more, the first and second overall areas (A1-A2, A21-A22) of the first exhaust port 241 and the second exhaust port 242 may not function properly due to the discharged explosion pressure, flames, and debris, and the first plate 21 may be completely torn.

[0051] Although the preferred embodiment of the present invention has been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the claims, the description of the invention, and the accompanying drawings, and it is to be understood that these modifications also fall within the scope of the present invention. [Explanation of symbols]

[0052] 11: First Holder 12: Second holder 21, 221: First plate 22: Second plate 30: Battery cell 31: Vent hole 32: Electrode assembly 33: Case 34: Cap assembly 35: Cap plate 36: Vent 40, 240: Outlet group 41: Outlet 100, 200: Secondary battery module 111: First storage section 113: 1st protrusion 121: Second storage section 123:Second protrusion 241: 1st outlet 242:Second outlet A1: 1st area A2:Second area A1-A2: (1st) Total area A3: Open area A4: Closed area A21: 1st area A22:Second area A21-A22: 2nd overall area A23:Second open area A24:Second closed area D1: 1st diameter D2: Second diameter D21: 21st diameter D22: 22nd diameter G: Gap G1: First interval G2: 2nd interval L1: First length L2: Second length W1: 1st width W2: Second width θ, θ2: angles

Claims

1. a plurality of battery cells with vent holes; a first holder that accommodates and supports one side of the battery cell; a second holder that accommodates and supports the other side of the battery cell and is coupled to the first holder; a first plate provided on one side of the second holder, the first plate including a group of exhaust ports each formed of a plurality of exhaust ports at positions corresponding to the vent holes of each of the battery cells; and a second plate disposed on one side of the first plate and connected to the vent hole and the group of exhaust ports to block exhaust material being discharged; Including, The outlet group has an outer first diameter (D1) and an inner second diameter (D2), and defines an overall area (A1-A2) as a region between an outer circle of the first diameter (D1) centered at the center of the outlet group and an inner circle of the second diameter (D2) centered at the center of the outlet group; The total area (A1-A2) includes an open area (A3*N) due to the plurality of first outlets and a closed area (A4*N) between the plurality of first outlets, The ratio of the closed area (A4*N) to the total area (A1-A2) is set to be greater than 10.78% and less than 31.3%.

2. The secondary battery module according to claim 1 , wherein the battery cells are formed from cylindrical secondary batteries.

3. the outlet has a first width in a diametrical direction and a first length in a circumferential direction; The secondary battery module according to claim 1 , wherein the outlet group includes a plurality of the outlets, the outlets being spaced apart from each other at first intervals in the circumferential direction.

4. The secondary battery module of claim 1 , wherein a ratio (A4*N) of the closed area to the total area (A1-A2) is further set to be greater than 10.78% and less than or equal to 15.4%.

5. The secondary battery module of claim 1 , wherein a ratio (A4*N) of the closed area to the total area (A1-A2) is further set to be greater than 15.4% and less than 31.3%.

6. A plurality of battery cells with vent holes; a first holder that accommodates and supports one side of the battery cell; a second holder that accommodates and supports the other side of the battery cell and is coupled to the first holder; a first plate provided on one side of the second holder, the first plate including a group of exhaust ports each formed of a plurality of exhaust ports at positions corresponding to the vent holes of each of the battery cells; and a second plate disposed on one side of the first plate and connected to the vent hole and the group of exhaust ports to block exhaust material being discharged; Including, The exhaust port group includes a plurality of first exhaust ports corresponding to the vent holes and a plurality of second exhaust ports provided on outer peripheries of the first exhaust ports.

7. the first outlet has a first width in a diametrical direction and a first length in a circumferential direction; The first outlets have a first circumferential spacing; the second outlet has a second width in a diametrical direction and a second length in a circumferential direction; The secondary battery module of claim 6 , wherein the second outlets are spaced apart at second intervals in the circumferential direction.

8. The first outlet has an outer first diameter (D1) and an inner second diameter (D2), and defines a first overall area (A1-A2) as an area between an outer circle of the first diameter (D1) centered at the center of the outlet group and an inner circle of the second diameter (D2) centered at the center of the outlet group; The first total area (A1-A2) includes an open area (A3*N) due to the plurality of first outlets and a first closed area (A4*N) between the plurality of first outlets, The second outlet has an outer 21st diameter (D21) and an inner 22nd diameter (D22), and defines a second overall area (A21-A22) as an area between an outer circle of the 21st diameter (D21) centered on the center of the outlet group and an inner circle of the 22nd diameter (D22) centered on the center of the outlet group; The second total area (A21-A22) includes an open area (A23*N) between the plurality of second outlets and a second closed area (A24*N) between the plurality of second outlets, 8. The secondary battery module of claim 7, wherein a ratio of the sum of the first closed area (A4*N) and the second closed area (A24*N) to the sum of the first total area (A1-A2) and the second total area (A21-A22) is set to be greater than 10.78% and less than 31.3%.

9. 9. The secondary battery module of claim 8, wherein a ratio of the sum of the first closed area (A4*N) and the second closed area (A24*N) to the sum of the first total area (A1-A2) and the second total area (A21-A22) is further set to be greater than 10.78% and less than or equal to 15.4%.

10. 9. The secondary battery module of claim 8, wherein a ratio of the sum of the first closed area (A4*N) and the second closed area (A24*N) to the sum of the first total area (A1-A2) and the second total area (A21-A22) is further set to be greater than 15.4% and less than 31.3%.

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