Battery module and battery pack

Abstract

A battery module comprises a plurality of battery cells accommodated in an arrangement within a housing, and a buffer member formed such that the reaction force acting on the battery cells is reduced at the central portion than at the peripheral portion, with the arrangement direction of the battery cells being in the thickness direction and positioned between adjacent battery cells and between the battery cells and the inner wall of the housing.

Description

Technology Field

[0001] The present disclosure relates to battery modules and battery packs. Background Technology

[0002] Japanese Patent Publication No. 2009-163932 discloses a battery pack in which an insulating buffer member is disposed between each stacked battery cell. In the battery pack described in Japanese Patent Publication No. 2009-163932, by disposing of an insulating buffer member between the battery cells, it is possible to suppress the direct rubbing of the battery cells against each other during product transport, and at the same time, to provide thermal insulation between the battery cells.

[0003] However, in order to improve the storage capacity per unit area of ​​a battery module, it is necessary to arrange battery cells without leaving gaps, but the battery pack disclosed in Japanese Patent Publication No. 2009-163932 cannot absorb the thermal expansion of the battery cells. In particular, the central part of the battery cell bulges in the thickness direction during thermal expansion, but the battery pack disclosed in Japanese Patent Publication No. 2009-163932 does not take into account such thermal expansion of the battery cells, so there is room for improvement. The problem to be solved

[0004] The present disclosure aims to obtain a battery module and a battery pack capable of absorbing the thermal expansion of a battery cell, taking into account the above facts. means of solving the problem

[0005] A battery module of a first embodiment comprises a plurality of battery cells accommodated in an arrangement within a housing, and a buffer member formed such that the reaction force acting on the battery cells is reduced at the central portion than at the peripheral portion, with the arrangement direction of the battery cells being in the thickness direction and disposed between adjacent battery cells and between the battery cells and the inner wall of the housing.

[0006] In a battery module of the first embodiment, a plurality of battery cells are accommodated in an arrangement within a housing. Additionally, a buffer member is disposed between adjacent battery cells and between a battery cell and the inner wall of the housing. Here, the buffer member is formed such that the arrangement direction of the battery cells is the thickness direction, and the reaction force acting on the battery cell is smaller in the central part of the buffer member than in the peripheral end part. Accordingly, when the battery cell undergoes thermal expansion and the central part of the battery cell bulges, the reaction force acting on the battery cell from the buffer member can be made approximately uniform between the central part and the peripheral end part, thereby allowing the thermal expansion of the battery cell to be absorbed by the buffer member.

[0007] In the battery module of the second embodiment, in the first embodiment, the buffer member is disposed at least in the central portion of the arrangement direction of the battery cell in the housing.

[0008] In the battery module of the second embodiment, by placing a buffer member in the central part of the arrangement direction of the battery cells, where the greatest stress is applied due to the thermal expansion of the battery cells, the thermal expansion of the battery cells can be effectively absorbed as a whole battery module.

[0009] In the battery module of the third embodiment, in the first embodiment, the buffer member is formed such that the thickness of the central portion is thinner than that of the peripheral end portion.

[0010] In the battery module of the third embodiment, by making the thickness of the central part of the buffer member thinner than the peripheral end, the reaction force acting on the battery cell from the central part of the buffer member can be made smaller than the reaction force acting on the battery cell from the peripheral end of the buffer member.

[0011] In the battery module of the fourth embodiment, in the first embodiment, the buffer member is formed such that the density of the central portion is lower than that of the peripheral portion.

[0012] In the battery module of the fourth embodiment, by making the density of the central part of the buffer member smaller than that of the peripheral end, the reaction force acting on the battery cell from the central part of the buffer member can be made smaller than the reaction force acting on the battery cell from the peripheral end of the buffer member.

[0013] In the battery module of the fifth embodiment, in the first embodiment, the buffer member is disposed between the inner walls on both sides of the housing and the battery cell.

[0014] In the battery module of the fifth embodiment, by placing a buffer member between the inner walls on both sides of the housing and the battery cell, the reaction force acting on the battery cell from the inner walls of the housing can be reduced.

[0015] In the battery module of the sixth embodiment, in the fifth embodiment, a central thick-walled buffer member is disposed in the central portion of the arrangement direction of the battery cells in the housing, such that the thickness of the central portion is thicker than that of the peripheral end portion.

[0016] In the battery module of the sixth embodiment, thermal expansion is absorbed by a cushioning member disposed between the inner walls on both sides of the housing and the battery cell, and the central part of the battery cell is bent by a central thick cushioning member disposed in the central part of the arrangement direction of the battery cell. By doing so, the terminals extending from the ends of the battery cells can be bent toward the center of the arrangement direction of the battery cells, thereby suppressing stress concentration on the terminals.

[0017] The battery pack of the seventh embodiment comprises a plurality of battery modules described in any one of the first to sixth embodiments.

[0018] In the battery pack of the seventh embodiment, the reliability of the entire battery pack can be improved by absorbing the thermal expansion of the battery cells in a plurality of battery modules. Effects of the invention

[0019] As described above, according to the battery module and battery pack of the present disclosure, thermal expansion of the battery cell can be absorbed. Brief explanation of the drawing

[0020] Exemplary embodiments of the present disclosure are described in detail based on the following drawings. FIG. 1 is a schematic plan view showing the main parts of a vehicle to which a battery pack according to a first embodiment is applied. Figure 2 is a schematic perspective view of a battery module. Figure 3 is a plan view of the battery module with the top cover removed. Figure 4 is a schematic diagram of a battery cell housed in a battery module viewed in the thickness direction. FIG. 5 is a schematic perspective view showing the main parts of a battery module in the first embodiment. FIG. 6 is a schematic diagram of a cushioning member in the first embodiment viewed in the thickness direction. FIG. 7 is a schematic plan view of a battery cell and a buffer member in a first embodiment. Figure 8 is a schematic diagram showing the state of a battery cell that has undergone thermal expansion from the state of Figure 7. FIG. 9 is a schematic plan view of a battery cell and a buffer member in a second embodiment. Figure 10 is a schematic diagram showing the state of a battery cell that has undergone thermal expansion from the state of Figure 9. Specific details for implementing the invention

[0021] <First Embodiment>

[0022] A battery pack (10) and a battery module (11) according to the first embodiment will be described with reference to the drawings.

[0023] (Overall configuration of the vehicle (100))

[0024] FIG. 1 is a schematic plan view showing the main parts of a vehicle (100) to which a battery pack (10) according to an embodiment is applied. As shown in FIG. 1, the vehicle (100) is a battery electric vehicle (BEV) with a battery pack (10) mounted on the bottom. In addition, the arrows UP, FR, and LH in each drawing represent the upper side in the vertical direction of the vehicle, the front side in the front-rear direction of the vehicle, and the left side in the width direction of the vehicle, respectively. When describing using the front-rear, left-right, and vertical directions, unless otherwise specified, they represent the front-rear direction of the vehicle, the left-right direction of the vehicle, and the upper-lower direction of the vehicle.

[0025] In the vehicle (100) of the present embodiment, as an example, a DC / DC converter (102), an electric compressor (104), and a PTC (Positive Temperature Coefficient) heater (106) are arranged on the front side of the vehicle relative to the battery pack (10). Additionally, a motor (108), a gearbox (110), an inverter (112), and a charger (114) are arranged on the rear side of the vehicle relative to the battery pack (10).

[0026] The direct current output from the battery pack (10) is supplied to the electric compressor (104), PTC heater (106), inverter (112), etc. after the voltage is adjusted by the DC / DC converter (102). Additionally, power is supplied to the motor (108) through the inverter (112), causing the rear wheels to rotate and drive the vehicle (100).

[0027] A charging port (116) is provided on the right side of the rear portion of the vehicle (100), and by connecting a charging plug of an external charging facility (not shown) to the charging port (116), power can be accumulated in the battery pack (10) through the vehicle-mounted charger (114).

[0028] In addition, the arrangement and structure of each component constituting the vehicle (100) are not limited to the configuration described above. For example, it may be applied to a hybrid vehicle (HV) or a plug-in hybrid electric vehicle (PHEV) equipped with an engine. Furthermore, in this embodiment, the vehicle is a rear-wheel drive vehicle with the motor (108) mounted on the rear of the vehicle, but it is not limited thereto; it may be a front-wheel drive vehicle with the motor (108) mounted on the front of the vehicle, or a pair of motors (108) may be mounted on the front and rear of the vehicle. Additionally, it may be a vehicle equipped with in-wheel motors on each wheel.

[0029] Here, the battery pack (10) is configured to include a plurality of battery modules (11). In this embodiment, as an example, 10 battery modules (11) are provided. Specifically, 5 battery modules (11) are arranged in the front-rear direction of the vehicle on the right side of the vehicle (100), and 5 battery modules (11) are arranged in the front-rear direction of the vehicle on the left side of the vehicle (100). Additionally, each battery module (11) is electrically connected.

[0030] FIG. 2 is a schematic perspective view of a battery module (11). As shown in FIG. 2, the battery module (11) is formed in the shape of a roughly rectangular parallelepiped with the vehicle width direction as the length direction. In addition, the outer shell of the battery module (11) is formed of an aluminum alloy. For example, the outer shell of the battery module (11) is formed by joining aluminum die casts to both ends of an extruded aluminum alloy material by laser welding or the like.

[0031] At each end of the battery module (11) in the vehicle width direction, a pair of voltage terminals (12) and a connector (14) are provided. A flexible printed circuit board (21), which will be described later, is connected to the connector (14). Additionally, a bus bar, not shown, is welded to both ends of the battery module (11) in the vehicle width direction.

[0032] The length MW in the vehicle width direction of the battery module (11) is, for example, 350 mm to 600 mm, the length ML in the vehicle front-rear direction is, for example, 150 mm to 250 mm, and the height MH in the vehicle up-down direction is, for example, 80 mm to 110 mm.

[0033] FIG. 3 is a plan view of the battery module (11) with the upper cover removed. As shown in FIG. 3, a plurality of battery cells (20) are accommodated in an arranged state inside the battery module (11). In this embodiment, as an example, 24 battery cells (20) are arranged in the front-rear direction of the vehicle and bonded to each other.

[0034] A flexible printed circuit board (FPC: Flexible Printed Circuit) (21) is disposed on the battery cell (20). The flexible printed circuit board (21) is formed in a strip shape with the vehicle width direction as the length direction, and a thermistor (23) is provided at each end of the flexible printed circuit board (21). The thermistor (23) is not attached to the battery cell (20) but is configured to be pressed toward the battery cell (20) by the upper cover of the battery module (11).

[0035] FIG. 4 is a schematic diagram of a battery cell (20) housed in a battery module (11) viewed in the thickness direction. As shown in FIG. 4, the battery cell (20) is formed in a roughly rectangular plate shape and houses an electrode body not shown inside. The electrode body is composed of a positive electrode, a negative electrode, and a separator stacked together and is sealed by a laminate film (22).

[0036] In this embodiment, as an example, a receiving portion of an electrode body is formed by folding and joining an embossed sheet-shaped laminate film (22). Additionally, both a single-cup embossed structure with one embossed location and a double-cup embossed structure with two embossed locations can be adopted, but in this embodiment, it is a single-cup embossed structure with a draw depth of about 8 mm to 10 mm.

[0037] The upper portions at both ends in the longitudinal direction of the battery cell (20) are bent and curved, and the corners are formed as an outer shape. Additionally, the upper portion of the battery cell (20) is bent and curved, and a fixing tape (24) is wrapped along the longitudinal direction of the upper portion of the battery cell (20).

[0038] Here, a tab (26) is provided at each of the longitudinal ends of the battery cell (20). In this embodiment, as an example, the tab (26) is provided at a position offset downward from the center of the battery cell (20) in the vertical direction. The tab (26) is joined to a bus bar (not shown) by laser welding or the like.

[0039] The length CW1 of the battery cell (20) in the vehicle width direction is, for example, 530mm to 600mm, 600mm to 700mm, 700mm to 800mm, 800mm to 900mm, 1000mm or more, the length CW2 of the area where the electrode body is accommodated is, for example, 500mm to 520mm, 600mm to 700mm, 700mm to 800mm, 800mm to 900mm, 1000mm or more, and the height CH of the battery cell (20) is, for example, 80mm to 110mm, 110mm to 140mm. In addition, the thickness of the battery cell (20) is 5.0mm to 7.0mm, 7.0mm to 9.0mm, and 9.0mm to 11.0mm, and the height TH of the tab (26) is 40mm to 50mm, 50mm to 60mm, and 60mm to 70mm.

[0040] (Buffer member (32, 34))

[0041] FIG. 5 is a schematic perspective view showing the main parts of a battery module (11) in an embodiment. As shown in FIG. 5, 24 battery cells (20) are accommodated without gaps in a module case (30) which serves as a housing for the battery module (11), arranged in the front-rear direction of the vehicle.

[0042] Additionally, one or more cushioning materials are accommodated inside the module case (30). In the present embodiment, as an example, a total of three cushioning materials, including one cushioning member (32) and two cushioning members (34), are accommodated inside the module case (30).

[0043] The buffer member (32) is formed as a thin plate-like member that is elastically deformable, and is positioned between adjacent battery cells (20) with the arrangement direction (vehicle front-rear direction) of the battery cells (20) as the thickness direction. In particular, the buffer member (32) is positioned in the central part of the vehicle front-rear direction in the module case (30). In this embodiment, as an example, 12 battery cells (20) are positioned on the vehicle front side of the buffer member (32), and 12 battery cells (20) are positioned on the vehicle rear side of the buffer member (32). Accordingly, the buffer member (32) is positioned at a location that divides the arranged plurality of battery cells (20) equally.

[0044] FIG. 6 is a schematic diagram of the buffer member (32) in the embodiment viewed in the thickness direction. FIG. 7 is a schematic plan view of the battery cell (20) and the buffer members (32, 34) in the embodiment. As shown in FIG. 6 and FIG. 7, the buffer member (32) in the embodiment is formed such that the thickness of the central part (32A) is thinner than that of the peripheral end (32B). In other words, the buffer member (32) is formed such that the reaction force acting on the battery cell (20) is smaller in the central part (32A) than in the peripheral end (32B). Also, in FIG. 7, for convenience of explanation, the lengths in the longitudinal direction of the battery cell (20), the buffer member (32), and the buffer member (34) are shown as shorter and differ from the actual relationship between thickness and length. The same applies to FIG. 8 to FIG. 10, which will be described later.

[0045] In the present embodiment, the cushioning member (32) is formed such that, as an example, the central portion (32A) is formed in a roughly rectangular shape when viewed in the thickness direction, and the thickness gradually decreases toward the center. Furthermore, it is not limited thereto, and the central portion (32A) may be formed in a roughly rectangular shape when viewed in the thickness direction, or in a roughly elliptical shape. Additionally, the cushioning member (32) is formed in an external shape when viewed in the thickness direction in a roughly rectangular shape, but is not limited thereto, and may be formed in a roughly rectangular shape with rounded corners.

[0046] Here, the central portion (32A) of the buffer member (32) is the region between the virtual line L1 and the virtual line L2 in FIG. 7. In the battery cell (20), the region between the virtual line L1 and the virtual line L2 corresponds to the active material coating region where the electrode active material is coated.

[0047] As shown in FIG. 5, two buffer members (34) are each positioned between the inner wall of the front and rear side wall (30A) of the module case (30) and the battery cell (20), with the thickness direction of the arrangement direction of the battery cell (20), that is, the front and rear direction of the vehicle. Because of this, one side of the buffer member (34) is in close contact with the battery cell (20), and the other side of the buffer member (34) is in close contact with the side wall (30A).

[0048] The buffer member (34) has an external shape approximately identical to that of the buffer member (32). That is, the buffer member (34) of the present embodiment is formed in an approximately rectangular shape when viewed in the thickness direction. In addition, as shown in FIG. 7, the buffer member (34) is formed such that the thickness of the central part (34A) is thinner than that of the peripheral end (34B). In other words, the buffer member (34) is formed such that the reaction force acting on the battery cell (20) is reduced in the central part (34A) compared to the peripheral end (34B).

[0049] The buffer member (34) located at the front of the vehicle is formed such that the central portion (34A) of the rear side of the vehicle, that is, the side adjacent to the battery cell (20), is concave toward the front of the vehicle, and the thickness gradually decreases toward the center. Additionally, the front side of the buffer member (34) is formed approximately flat along the inner wall (not shown) of the module case (30).

[0050] Meanwhile, the buffer member (34) located at the rear of the vehicle has a shape that is symmetrical to the buffer member (34) located at the front of the vehicle. That is, the buffer member (34) located at the rear of the vehicle has a central portion (34A) of the front side of the vehicle, that is, the side adjacent to the battery cell (20), which is concave toward the rear of the vehicle, and is formed in a shape in which the thickness gradually decreases toward the center. In addition, the front side of the buffer member (34) is formed in a roughly flat shape along the inner wall (not shown) of the module case (30). Also, in FIG. 7, for convenience of explanation, the difference in thickness between the central portion (32A) and the surrounding end portion (32B) of the buffer member (32), and the difference in thickness between the central portion (34A) and the surrounding end portion (34B) of the buffer member (34) are depicted in an exaggerated manner. In reality, there is no gap or almost no gap between the central part (32A) of the buffer member (32) and the battery cell (20). Likewise, in reality, there is no gap or almost no gap between the central part (34A) of the buffer member (34) and the battery cell (20).

[0051] FIG. 8 is a schematic diagram showing the state in which the battery cell (20), the buffer member (32), and the buffer member (34) are housed in a module case (30) and the battery cell (20) is thermally expanded. As shown in FIG. 8, the battery cell (20) is thermally expanded by repeated charging and discharging. In particular, the active material coating area in the battery cell (20) is thermally expanded, causing the central part of the battery cell (20) to bulge outward.

[0052] Here, in this embodiment, since the thickness of the central part (32A) of the buffer member (32) is thin, the central part of the battery cell (20) fits into this thinned part, so that the reaction force acting on the battery cell (20) from the buffer member (32) can be made equal in the central part and the surrounding end part. Likewise, since the thickness of the central part (34A) of the buffer member (34) is thin, the central part of the battery cell (20) fits into this thinned part, so that the reaction force acting on the battery cell (20) from the buffer member (34) can be made equal in the central part and the surrounding end part.

[0053] (action)

[0054] Next, the operation of the battery module (11) and battery pack (10) according to the present embodiment will be explained.

[0055] In the battery module (11) according to the present embodiment, a plurality of battery cells (20) are accommodated in an arrangement inside the module case (30). Additionally, a buffer member (32) is disposed between adjacent battery cells (20), and a buffer member (34) is disposed between the battery cells (20) and the inner wall of the module case (30).

[0056] Here, the buffer members (32) and (34) are formed such that the arrangement direction of the battery cell is in the thickness direction, and the reaction force acting on the battery cell (20) is reduced in the central part (32A, 34A) than in the peripheral end part (32B, 34B) of each buffer member (32, 34). Accordingly, when the battery cell (20) undergoes thermal expansion and the central part of the battery cell (20) bulges, the reaction force acting on the battery cell (20) from the buffer members (32, 34) can be made approximately uniform in the central part and the peripheral end part, so that the thermal expansion of the battery cell (20) can be absorbed by the buffer members (32, 34).

[0057] In addition, because the greatest stress is applied to the central part of the battery module (11) in the front-rear direction due to the thermal expansion of the battery cell (20), by placing a buffer member (32) in the central part of the battery module (11), the thermal expansion of the battery cell (20) can be effectively absorbed as a whole by the battery module (11).

[0058] In addition, in this embodiment, by making the thickness of the central portion (32A, 34A) of the buffer member (32, 34) thinner than the peripheral portion (32B, 34B), the reaction force acting on the battery cell (20) from the peripheral portion (32B, 34B) of the buffer member (32, 34) can be made smaller than the reaction force acting on the battery cell (20) from the peripheral portion (32B, 34B) of the buffer member (32, 34).

[0059] In addition, in this embodiment, by placing a buffer member (34) between the inner wall of the side wall (30A) on both sides of the module case (30) and the battery cell (20), the reaction force acting on the battery cell (20) from the inner wall of the module case (30) can be reduced.

[0060] <Second Embodiment>

[0061] Next, the battery module (50) according to the second embodiment will be described with reference to the drawings. Additionally, configurations similar to those in the first embodiment are given the same reference numerals and descriptions are omitted as appropriate.

[0062] FIG. 9 is a schematic plan view of a battery cell and a buffer member in a second embodiment. As shown in FIG. 9, the battery module (50) of this embodiment has the same structure as the first embodiment, except for the central thick buffer member (52).

[0063] The central thick cushioning member (52) is positioned in the central part of the arrangement direction of the battery cells (20) in the battery module (50), with the arrangement direction of the battery cells (20) as the thickness direction. Additionally, the central thick cushioning member (52) is formed in an approximate rectangular shape when viewed from the thickness direction.

[0064] Here, the central thick cushioning member (52) of the present embodiment is formed such that the thickness of the central part (52A) is thicker than that of the surrounding end part (52B).

[0065] (action)

[0066] Next, the operation of the battery module (50) in this embodiment is explained.

[0067] FIG. 10 is a schematic diagram showing the state in which the battery cell (20) has undergone thermal expansion from the state of FIG. 9. As shown in FIG. 10, in this embodiment, the thermal expansion of the battery cell (20) is absorbed by the buffer members (34) arranged on both the front and rear sides of the battery module (50).

[0068] In addition, the central part of the battery cell (20) is bent by a central thick cushioning member (52) positioned in the central part of the vehicle's front and rear direction. By doing so, the tab (26) extending from the end of the battery cell (20) can be bent toward the center of the battery cell (20)'s arrangement direction, thereby suppressing stress concentration on the tab (26).

[0069] That is, if only the tab (26) is bent, stress is concentrated at the base of the tab (26), and there is a possibility that the tab (26) may be damaged; however, by bending the battery cell (20) itself as in this embodiment, the concentration of stress at the base of the tab (26) can be suppressed. Other functions are the same as in the first embodiment.

[0070] Although the battery pack (10) and battery module (11) according to the present embodiment have been described above, they are not limited thereto and can be implemented in various forms within the scope of not departing from the gist of the present disclosure. For example, in the first embodiment above, as shown in FIG. 7, the buffer members (32, 34) are shaped such that their thickness gradually decreases from the peripheral ends (32B, 34B) toward the central part (32A, 34A), but they are not limited thereto. For example, they may be shaped such that their thickness decreases in a stepped manner by adding a step.

[0071] Additionally, the buffer member (32, 34) is formed such that the central portion (32A, 34A) has a thinner thickness than the peripheral portion (32B, 34B), but is not limited thereto. In another embodiment, a buffer member may be used in which the density of the central portion is lower than that of the peripheral portion. For example, when forming the buffer member with foamed resin, a buffer member with a lower density of the central portion than that of the peripheral portion may be formed by controlling the amount of foaming. By making the density of the central portion of the buffer member lower than that of the peripheral portion, the reaction force acting on the battery cell from the central portion of the buffer member can be made smaller than the reaction force acting on the battery cell from the peripheral portion of the buffer member. As a result, similar to the above embodiment, the reaction force acting on the battery cell (20) from the buffer member during thermal expansion of the battery cell (20) can be made approximately uniform between the central portion and the peripheral portion, thereby obtaining the effect of absorbing the thermal expansion of the battery cell (20) by the buffer member.

[0072] In addition, materials with different elastic moduli may be used in the central part and the peripheral end part of the buffer member. Specifically, by making the material in the central part of the buffer member a material with a lower elastic modulus than the material in the peripheral end part, the reaction force acting on the battery cell from the central part of the buffer member can be made smaller than the reaction force acting on the battery cell from the peripheral end part of the buffer member, just as in the above embodiment.

[0073] Regarding the above embodiment, the following supplementary information is disclosed.

[0074] (Appendix 1)

[0075] A plurality of battery cells accommodated in an arranged state inside a housing, and

[0076] A buffer member formed such that the reaction force acting on the battery cell is reduced at the central portion than at the peripheral portion, with the arrangement direction of the battery cell being the thickness direction and disposed between adjacent battery cells and between the battery cell and the inner wall of the housing.

[0077] Battery module having.

[0078] (Appendix 2)

[0079] The above buffer member is a battery module described in Appendix 1, which is disposed in the central portion of the arrangement direction of the battery cells in the housing.

[0080] (Appendix 3)

[0081] The above buffer member is a battery module described in Appendix 1 or Appendix 2, wherein the thickness of the central portion is formed to be thinner than that of the peripheral ends.

[0082] (Appendix 4)

[0083] The above buffer member is a battery module described in any one of Appendix 1 to Appendix 3, wherein the density of the central portion is lower than that of the peripheral ends.

[0084] (Appendix 5)

[0085] The above buffer member is a battery module described in any one of Appendix 1 to Appendix 4, disposed between the inner walls on both sides of the housing and the battery cell.

[0086] (Appendix 6)

[0087] A battery module described in Appendix 5, wherein a central thick-walled buffer member is disposed in the central portion of the arrangement direction of the battery cells in the housing, such that the thickness of the central portion is thicker than that of the peripheral ends.

[0088] (Appendix 7)

[0089] A battery pack having a plurality of battery modules described in any one of Appendix 1 to 6.

Claims

Claim 1 A battery module having a plurality of battery cells accommodated in an arranged state inside a housing, a buffer member disposed between the battery cells and the inner walls on both sides of the housing with the arrangement direction of the battery cells as the thickness direction, formed such that the reaction force acting on the battery cells is reduced towards the center than towards the peripheral ends, and a central thick buffer member disposed in the central part of the arrangement direction of the battery cells in the housing, with the thickness gradually increasing from the peripheral ends to the center. Claim 2 A battery module according to claim 1, wherein, when the battery cell is in a state of thermal expansion, the central portion of the battery cell is bent by the central thick-walled buffer member. Claim 3 In claim 1, the above buffer member is a battery module having a thickness in the central portion that is thinner than the surrounding ends. Claim 4 In claim 1, the buffer member is a battery module formed such that the density of the central portion is lower than that of the peripheral ends. Claim 5 delete Claim 6 delete Claim 7 A battery pack having a plurality of battery modules described in any one of paragraphs 1 to 4.

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