Battery pack

Abstract

To provide a battery pack which can achieve improvement of loading efficiency of the battery module, while inhibiting increase of weight of the battery module and inhibit thermal chain when thermal runaway of a battery cell occurs.SOLUTION: A battery pack includes a case, a battery module disposed in the case, and a cover covering an upper side of the battery module. The battery module includes: a laminated body in which a plurality of secondary batteries is laminated; and side restraint members each facing a first surface of the laminated body and extending in a lamination direction of the laminated body. The first surface is a surface arranged in a direction perpendicular to a lower surface of the laminated body and along the lamination direction. A first distance between an upper end of the side restraint member and the cover is shorter than a second distance between an upper surface of the laminated body and the cover.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a battery pack. [Background technology]

[0002] In recent years, research and development into secondary batteries that contribute to energy efficiency has been conducted to ensure that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] Patent Document 1 discloses a battery module comprising a stack of multiple battery cells (secondary batteries), a pair of bind bars, and a pair of end plates. The pair of bind bars are members that restrain the stacking direction of the multiple battery cells, and the pair of end plates are members that restrain the battery cells in the width direction (a direction intersecting the stacking direction). The pair of bind bars and the pair of end plates are components whose main purpose is to hold and protect the stack of multiple battery cells.

[0004] A battery pack is formed by mounting (arranging) multiple battery modules in a housing (case) that protects them from external forces. The battery pack housing is provided with structural members such as cross members and side frames to ensure strength, rigidity, and resistance to external forces, and to connect to the vehicle.

[0005] The cross member is a structural member that extends in the stacking direction of the battery cells inside the housing, in the same direction as the bind bar that restrains the battery cells in the stacking direction. The side frame is a structural member that extends in the arrangement direction of the battery cells inside the housing (a direction intersecting the stacking direction), in the same direction as the end plate that restrains the battery cells in the width direction.

[0006] The cross members and side frames contribute to the strength and rigidity of the battery pack housing in the fore-and-aft and lateral directions of the vehicle, as well as resistance to external forces, and the cross members and side frames hold and protect multiple battery modules within the housing. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2019 / 167689 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the structural members (cross members, side frames) provided on the housing and the structural members (bind bars, end plates) that make up the battery module are provided independently, which can be inefficient in terms of cost, weight, and securing space for mounting the battery module in the housing.

[0009] When battery modules are fixed with bind bars and end plates, and multiple battery modules are held in place with cross members and side frames to ensure strength, rigidity, and resistance to external forces, the weight of the battery modules increases, so it is necessary to suppress this weight increase.

[0010] Furthermore, structural members (bind bars, end plates) that make up the battery module and structural members (cross members, side frames) attached to the housing (hereinafter also referred to as the case) partially occupy the mounting space for the battery cells within the case, so there is a need to improve the mounting efficiency of battery modules that include secondary batteries. Also, in battery packs that include multiple battery modules, there is a need to suppress thermal chain reactions when battery cells experience thermal runaway. [Means for solving the problem]

[0011] In consideration of the above-mentioned problems, the present application provides a battery pack that can suppress thermal chain reactions when a battery cell experiences thermal runaway in a battery module that can improve mounting efficiency while suppressing an increase in the weight of the battery module.

[0012] A battery pack according to one aspect of the present invention includes a case, a battery module disposed in the case, and a cover covering an upper portion of the battery module, The battery module includes: a stacked body in which a plurality of secondary batteries are stacked; a side restraint member facing the first surface of the stack and extending in the stacking direction of the stack, the first surface is a surface that is perpendicular to the lower surface of the stack and is along the stacking direction, A first distance between the upper end of the side restraining member and the cover is shorter than a second distance between the upper surface of the stack and the cover. Ku, The battery module includes: a plurality of the laminated bodies are arranged in a direction intersecting the first surface of the laminated body, The side restraint member is the battery module is disposed in a state facing in the intersecting direction another side restraint member of another battery module disposed adjacently in the case, the cover has a plurality of protrusions extending downward toward the battery module at positions spaced apart along the intersecting direction, The side restraint member and the other side restraint member are positioned between the plurality of protrusions. It is characterized by: [Effects of the Invention]

[0013] According to the present invention, a battery pack can be provided that can suppress thermal chain reactions when a battery cell experiences thermal runaway in a battery module that can improve mounting efficiency while suppressing an increase in the weight of the battery module. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram illustrating a schematic configuration of a battery module and a battery module group according to an embodiment; [Figure 2]5A and 5B are diagrams illustrating a joining structure between a battery cell and a side restraint member according to an embodiment. [Figure 3] 1A and 1B are diagrams illustrating a structure in which a battery module group is arranged in a case according to an embodiment. [Figure 4] 1A and 1B are diagrams showing a first example of a connecting structure for connecting end restraint members according to an embodiment. [Figure 5] 10A and 10B are diagrams showing a second example of a connecting structure for connecting end restraint members according to an embodiment. [Figure 6] 10A and 10B are diagrams showing a third example of a connecting structure for connecting end restraint members according to an embodiment. [Figure 7] 1A and 1B are diagrams illustrating a cross-sectional structure of a battery cell according to an embodiment; [Figure 8] 10A and 10B are diagrams illustrating a thermal chain reaction prevention structure of a battery pack according to a second embodiment. [Figure 9] 10A and 10B are diagrams illustrating a thermal chain reaction prevention structure of a battery pack according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be arbitrarily combined. Furthermore, the same reference numerals are used for the same or similar components, and redundant explanations will be omitted.

[0016] [Embodiment] <Battery module 110, battery module group 115> FIG. 1 is a diagram for explaining the schematic configuration of a battery module 110 and a battery module group 115 according to the embodiment.

[0017] 1A, a plurality of battery cells 100 (secondary batteries) are arranged in the X direction (stacking direction), and a stack 111 is formed by stacking the plurality of battery cells 100. A heat insulating material (not shown) may be arranged between the battery cells 100 arranged in the X direction.

[0018] 1, the X direction (stacking direction) of the laminate 111 is defined as a first direction. Also, the direction (Y direction) intersecting with the surface (XZ plane: first surface 101) of the plurality of battery cells 100, i.e., the surface (XZ plane: first surface 101) of the battery module 110 (laminated body 111) is defined as a second direction (intersecting direction). The direction intersecting with the first and second directions is defined as a third direction (vertical direction).

[0019] Furthermore, the surface of the battery cell 100 in the X direction and the Z direction (XZ surface) and the surface of the battery module 110 (laminated body 111) in the X direction and the Z direction (XZ surface) are defined as the first surface 101, and the surface of the battery cell 100 in the Y direction and the Z direction (YZ surface) and the surface of the battery module 110 (laminated body 111) in the Y direction and the Z direction (YZ surface) are defined as the second surface 102.

[0020] The first surface 101 is a surface that is perpendicular to the bottom surface (XY plane) of the battery module 110 (laminated body 111) and is a surface that is aligned with the stacking direction. The second surface 102 is a surface that is perpendicular to the bottom surface (XY plane) of the battery module 110 (laminated body 111) and is a surface that intersects with the stacking direction. Here, the bottom surface (XY plane) of the laminated body 111 is the surface on which the laminated body 111 is placed in the case 400 (battery case: FIG. 3).

[0021] The surface (XZ surface) of the battery module 110 (laminated body 111) is a surface formed by the surfaces (XZ surface: first surface 101) of the multiple battery cells 100. The surface (YZ surface) of the battery module 110 (laminated body 111) is a surface in the Y direction and Z direction (YZ surface: second surface 102) of the battery cell 100 arranged at the end of the multiple battery cells 100 that constitute the laminated body 111.

[0022] As shown in FIG. 1B, the side restraint members 200 (200a, 200b) face the first surface 101 (XZ surface) of the battery module 110 (stacked body 111) and extend in the X direction (stacking direction) of the stacked body 111.

[0023] The first surface 101 (XZ surface) of each battery cell 100 constituting the stack 111 and the side restraint members 200 (200a, 200b) are joined by a joining member.

[0024] FIG. 2 is a diagram illustrating the joining structure between the battery cell 100 and the side restraint member 200. FIG. 2 is a diagram illustrating the battery cell 100 as viewed from the YZ plane (second surface 102), and an insulating film 702 is provided between a joining member 701 (for example, an adhesive or double-sided tape) and the battery cell 100. The insulating film 702 is provided so as to cover the interface with the joining member 701 as well as parts of the lower and upper surfaces of the battery cell 100. The type of insulating film 702 is not particularly limited, and may be a resin material. Examples of the resin material may include polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), etc.

[0025] The gap between the battery cell 100 and the case 400 (battery case) is filled with filler 703. The type of filler 703 is not particularly limited, and may be a resin material. The insulating film 702 and filler 703 may be made of a flame-retardant material so as to be able to withstand exposure to high temperatures due to thermal runaway of the battery cell 100.

[0026] When an adhesive is used as the joining member 701, the adhesive may be filled between the first surface 101 (XZ surface) and the side restraint member 200 to join them. The type of adhesive is not particularly limited, and examples include acrylic resin, urethane resin, silicon resin, epoxy resin, and olefin resin.

[0027] In a side view of the YZ plane (second surface 102), the side restraint member 200 joined to the left side of the battery cell 100 on the paper surface is referred to as the side restraint member 200 (200a). The side restraint member 200 joined to the right side of the battery cell 100 on the paper surface is referred to as the side restraint member 200 (200b). The terms "side restraint member 200" or "side restraint member 200 (200a, 200b)" refer collectively to the side restraint member 200 (200a) and the side restraint member 200 (200b).

[0028] Furthermore, the first surface 101 (XZ surface) of the battery cell 100 on the left side of the paper surface will be referred to as the first surface 101 (101a), and the first surface 101 (XZ surface) of the battery cell 100 on the left side of the paper surface will be referred to as the first surface 101 (101b). The terms "first surface 101" or "first surface 101 (XZ surface)" refer collectively to the first surface 101 (101a) and the first surface 101 (101b).

[0029] The first surface 101 (101a) and the first surface 101 (101b) of the battery cell 100 have the same junction structure.

[0030] 2, the battery cell 100 shown by the dashed line indicates another battery cell 100 arranged adjacent to the battery cell 100 shown by the solid line in the Y direction. The side restraint member 200 (200b) shown by the dashed line is joined to the battery cell 100 by a joining structure similar to that of the side restraint member 200 (200a).

[0031] In FIG. 2, the side restraint member 200 (200a) faces the first surface 101 (101a) at one end in the Y direction, and the side restraint member 200 (200b) faces the first surface 101 (101b) at the other end in the Y direction.

[0032] The side restraint members 200 (200a, 200b) are plate-shaped members made of metal such as aluminum, aluminum alloy, copper, iron, iron alloy, stainless steel, etc. The shape of the side restraint members 200 (200a, 200b) is not particularly limited as long as they can hold and restrain the first surfaces 101 (101a, 101b: XZ surfaces) of each battery cell 100 constituting the battery module 110 (stacked body 111).

[0033] As shown in Figure 1B and Figure 2, in a side view of the YZ plane (second surface 102), a pair of side restraint members 200 (200a, 200b) face the first surface 101 (101a) at one end side in the Y direction of the YZ plane (second surface 102) of the stack 111 (battery cell 100) and the first surface 101 (101b) at the other end side in the Y direction, and extend in the stacking direction of the stack 111 (battery cell 100).

[0034] The side restraint members 200 (200a, 200b) hold and restrain the stacking direction (X direction: first direction) of the battery module 110 (stacked body 111), and can also provide strength and rigidity to the battery module 110 (stacked body 111), and function as members that protect the battery module 110.

[0035] As shown in 1C of FIG. 1, multiple battery modules 110 (stacked body 111) are arranged in a case (400 of FIG. 3) in which the battery modules 110 (stacked body 111) are arranged in a second direction (Y direction) that is vertical to the underside of the stacked body 111 and intersects the stacking direction.

[0036] The side restraint members 200 (200a, 200b) face, in the second direction, the side restraint members 200 of other battery modules 110 arranged adjacently inside the case (400 in FIG. 3).

[0037] For example, among multiple battery modules 110, the side restraint member 200 (e.g., solid line in Figure 2) of one battery module 110 and the side restraint member 200 (e.g., dashed line in Figure 2) of another battery module 110 arranged adjacently along the second direction (Y direction) are arranged in the case 400 facing each other in the second direction.

[0038] As shown in FIG. 1D, the battery module 110 further includes end restraint members 300 connected to the side restraint members 200 and holding the YZ surface (second surface 102) of the battery module 110 (stacked body 111).

[0039] 1D, in a side view of the XZ plane (first surface 101), the end restraint member 300 on the right side of the battery module 110 is referred to as end restraint member 300 (300a). The end restraint member 300 on the left side of the battery module 110 is referred to as end restraint member 300 (300b). The terms "end restraint member 300" or "end restraint member 300 (300a, 300b)" refer collectively to the end restraint member 300 (300a) and the end restraint member 300 (300b).

[0040] Additionally, the end restraint member 300 of each battery module 110 is connected along the second direction (Y direction) to the end restraint member 300 of another adjacent battery module 110 to form a long end restraint member 310. The long end restraint member 310 on the right side of the battery module 110 in the drawing will be referred to as the long end restraint member 310 (310a). The long end restraint member 310 on the left side of the battery module 110 in the drawing will be referred to as the long end restraint member 310 (310b). The terms "long end restraint member 310" or "long end restraint member 310 (310a, 310b)" refer collectively to the long end restraint member 310 (310a) and the long end restraint member 310 (310b).

[0041] In addition, in a side view of the XZ plane (first surface 101), the second surface 102 (YZ surface) at one end side in the X direction of the battery module 110 is referred to as the second surface 102 (102a), and the second surface 102 (YZ surface) at the other end side in the X direction is referred to as the second surface 102 (102b). The terms "second surface 102 (YZ surface)" or "second surface 102 (102a, 102b)" refer collectively to the second surface 102 (102a) and the second surface 102 (102b).

[0042] The end restraint member 300 is a plate-like member made of metal such as aluminum, aluminum alloy, copper, iron, iron alloy, stainless steel, etc. The shape of the end restraint member 300 is not particularly limited as long as it can hold and restrain the second surface 102 (YZ surface) of the battery module 110 (stacked body 111).

[0043] 1D, in a side view in the XZ plane direction, the pair of end restraint members 300 (300a, 300b) extend opposite the second surface 102 (102a) at one end in the X direction of the battery module 110 and the second surface 102 (102b) at the other end in the X direction. That is, the end restraint member 300 (300a) faces the second surface 102 (102a) at one end in the X direction, and the end restraint member 300 (300b) faces the second surface 102 (102b) at the other end in the X direction.

[0044] The end restraint member 300 holds and restrains the arrangement direction (Y direction: second direction) of the battery module 110 (stacked body 111), and can also function as a member that provides strength and rigidity to the battery module 110 (stacked body 111) and protects the battery module 110.

[0045] The end restraint members 300 (300a, 300b) of each battery module 110 are connected and extend along the second direction (Y direction). The end restraint members 300 (300a, 300b) connected along the second direction (Y direction) are configured as elongated end restraint members 310 (310a, 310b). The elongated end restraint members 310 (310a, 310b) hold and restrain the arrangement direction (Y direction: second direction) of the assembly of multiple battery modules 110 (battery module group 115), and can also provide strength and rigidity to the battery module group 115 and function as members that protect the battery module group 115. The connection structure for connecting the end restraint members 300 will be described with reference to FIGS. 4 to 6.

[0046] FIG. 1E shows an assembly (battery module group 115) of the battery modules 110 arranged in an arrangement direction (Y direction: second direction).

[0047] 1E, six battery modules 110 are arranged, but any number of battery modules 110 may be arranged to form the battery module group 115. Electrical components 116 are attached to each of the battery modules 110 that form the battery module group 115. The electrical components 116 include, for example, conductive members (bus bars) that electrically connect terminals between the battery cells 100 that form the stack 111, voltage detection wires that detect voltages from each battery cell 100, and the like.

[0048] In the battery module group 115, the side restraint members 200 (200a, 200b) of each battery module 110 hold and restrain the battery modules 110 (stacked body 111) in the stacking direction (X direction: first direction), and can also function as members that provide strength and rigidity to the battery modules 110 (stacked body 111) and protect the battery modules 110. That is, in the battery module group 115 made up of a plurality of battery modules 110, the side restraint members 200 (200a, 200b) have a function that combines the cross members of a housing (case) in conventional technology and the bind bars that make up the battery modules.

[0049] In the prior art, the functions performed by the cross member of the housing (case) and the functions performed by the bind bar can be consolidated into the side restraint member 200 (200a, 200b) in the battery module 110 and battery module group 115 of this embodiment.

[0050] In addition, the long end restraint members 310 (310a, 310b) hold the arrangement direction (Y direction: second direction) of the assembly of multiple battery modules 110 (battery module group 115), restrain the battery module group 115, and provide strength and rigidity to the battery module group 115, and can function as a member to protect the battery module group 115.

[0051] The long end restraint members 310 (310a, 310b) have a function that integrates the side frames of a housing (case) in the prior art and the end plates that constitute the battery module.

[0052] In the battery module 110 and battery module group 115 of the present embodiment, the functions that were previously performed by the side frames of the housing (case) and the functions that were previously performed by the end plates can be integrated into the end restraint members 300 (300a, 300b) and the long end restraint members 310 (310a, 310b). This provides the battery module 110 and the battery module group 115, which is made up of multiple battery modules 110, with sufficient strength and rigidity.

[0053] <Battery Pack 500> A battery pack 500 is configured by mounting (arranging) a plurality of battery modules 110 (battery module group 115) in a case 400 for protecting them from external forces and covering the top with a cover 410. The battery pack 500 can be mounted, for example, in an electric vehicle such as a hybrid car or an EV (not shown).

[0054] 3 is a diagram illustrating a structure in which a battery module group 115 is arranged in a case 400 (battery case). The case 400 is a tray-shaped case, and the bottom plate of the case 400 can be made of a material that has insulating properties and excellent thermal conductivity. The fastening members 460 are members for fixing the battery module group 115 to the case 400, and include, for example, fastening bolts.

[0055] 1 are formed with holes (through holes) through which fastening members 460 for fixing the battery module group 115 to the case 400 can pass. The case 400 is formed with, for example, threaded portions (e.g., female screws) that threadably engage with the fastening members 460 (e.g., fastening bolts). The case 400 is fitted with a control unit 420 that controls the power supplied from the battery module group 115 and an interface section 430 that includes, for example, a connector for connecting to an external device.

[0056] A frame 450 that reinforces the case 400 is attached to the underside of the case 400. The frame 450 is a member that extends along one side of the case 400 (for example, the side in the Y direction in FIG. 2). The frame 450 contributes to improving the strength and rigidity of the case 400. In order to reduce the weight of the battery pack 500, the frame 450 may have a substantially hollow structure in which reinforcing portions 455 such as ribs are formed upward in the extension direction (for example, the Z direction in FIG. 2). The number of reinforcing portions 455 is not particularly limited, and it is sufficient that at least one reinforcing portion 455 is formed. Furthermore, in the example of FIG. 2, the frame 450 extends along the Y direction of the case 400, but the extension direction of the frame 450 is not limited to the Y direction, and an additional frame 450 extending along the X direction may be provided.

[0057] Frame fastening member 470 is a member for fixing frame 450 to case 400, and includes, for example, a fastening bolt. Frame 450 is formed with a hole (through hole) through which frame fastening member 470 for fixing frame 450 to case 400 can pass. Case 400 is formed with, for example, a threaded portion (for example, a female screw) that screws into frame fastening member 470 (for example, a fastening bolt).

[0058] The cover 410 is a member that covers the top of the battery module group 115 (plurality of battery modules 110) arranged in the case 400, and is fastened to the case 400 by fastening members (not shown). This seals the battery module group 115, and the battery pack 500 is formed.

[0059] In the configuration of the battery module group 115, by consolidating the functions of the structural members into the side restraint members 200 and the end restraint members 300, it is possible to reduce the weight of the battery module group 115. Furthermore, by consolidating the functions of the structural members, it is possible to provide a battery pack 500 that can improve the mounting efficiency of the battery modules 110 within the case 400.

[0060] <Connection structure example 1> The end restraint members 300 of each battery module 110 are connected to the end restraint members 300 of other battery modules 110 arranged adjacently along the second direction (Y direction), thereby forming long end restraint members 310.

[0061] FIG. 4 is a diagram showing a first example of a connecting structure for connecting end restraint members 300 (300a) according to an embodiment. In the first example of a connecting structure, a connecting structure using a connecting pin 610 is described. In the example of FIG. 4, one end restraint member 300 (300a) is connected to another end restraint member 300 (300a). The end restraint member 300 (300a) is connected to the other end restraint member 300 (300a) by fitting the connecting pin 610, which abuts both the end restraint member 300 (300a) and the other end restraint member 300 (300a).

[0062] Recesses 611, 612 that fit with the connecting pin 610 are formed on the YZ plane of one end restraint member 300 (300a). The connecting pin 610 fits into the recess 611 (first fitting portion) of one end restraint member 300 (300a) and the recess 612 (second fitting portion) of the other end restraint member 300, thereby connecting the one end restraint member 300 (300a) and the other end restraint member 300 (300a).

[0063] The recesses 611 (first fitting portion) and 612 (second fitting portion) may be formed in different shapes so that the fitting state in the recess 611 (first fitting portion) differs from the fitting state in the recess 612 (second fitting portion) when the connecting pin 610 is fitted in each of them. For example, the different shapes may be such that the opening dimensions of the recesses are different so that the dimensional tolerances are different.

[0064] When the connecting pin 610 is fitted into the recess 611 (first fitting portion) and the recess 612 (second fitting portion), each fitting portion may be formed with a surface roughness such that the fitting state in the recess 611 (first fitting portion) differs from the fitting state in the recess 612 (second fitting portion).

[0065] For example, recess 611 may be formed to create a tight fitting state (first fitting state), and recess 612 may be formed to create a looser fitting state (second fitting state) than the first fitting state.

[0066] 4, at least different types of recesses 611, 612 are formed on the YZ surface of one end restraint member 300 (300a). That is, it is sufficient that the recess 611 for the first fitted state and the recess 612 for the second fitted state are formed on the YZ surface of one end restraint member 300 (300a).

[0067] The side restraint member 200 (200a) in one battery module 110 is connected to (contacts) one end restraint member 300 (300a). The side restraint member 200 (200b) in another adjacent battery module 110 is connected to (contacts) another end restraint member 300 (300a).

[0068] When the end restraint members 300 (300a) are connected to each other, the adjacent side restraint members 200 (200a) and 200 (200b) are held in a sandwiched state between one end restraint member 300 (300a) and the other end restraint member 300 (300a). The end restraint member 300 (300a) has a hole (through hole) formed therein through which the fastening member 460 can pass, and the fastening member 460 connects the end restraint member 300 (300a) to the case 400 in which the battery module 110 is arranged.

[0069] The battery module 110, which is held in the XZ plane by the side restraint members 200 (200a, 200b), is held (connected) to the case 400 via the side restraint members 200 (200a, 200b) and the end restraint members 300 (300a, 300b).

[0070] Note that, in the end restraint members 300 (300b) on the other end side of the battery module 110, the adjacent end restraint members 300 (300b) can be similarly connected to each other using the same connecting structure example 1.

[0071] In a connection structure using connecting pins 610, one side is tightly fitted (first fitted state) and the other side is loosely fitted (second fitted state), thereby improving the ease of assembly when connecting end restraint members 300. In other words, even before the end restraint members 300 are connected to each other, it becomes easy to align the side restraint members 200 in each battery module 110, making it easier to adjust the positional relationship between the side restraint members 200 and the end restraint members 300.

[0072] <Connection structure example 2> Figure 5 is a diagram showing a second example of a connecting structure for connecting end restraint members 300 (300a) according to the embodiment. In the second example of a connecting structure, a connecting structure using a stiffener 620 will be described. As with the first example of a connecting structure, the example in Figure 5 will be described assuming that one end restraint member 300 (300a) is connected to another end restraint member 300 (300a).

[0073] In connection structure example 2, similarly to connection structure example 1, the side restraint member 200 (200a) in one battery module 110 is connected to (contacts) one end restraint member 300 (300a). Also, the side restraint member 200 (200b) in another adjacent battery module 110 is connected to (contacts) another end restraint member 300 (300a).

[0074] When the end restraint members 300 (300a) are connected to each other, the adjacent side restraint members 200 (200a) and 200 (200b) are held in a sandwiched state between one end restraint member 300 (300a) and the other end restraint member 300 (300a).

[0075] As shown in Fig. 5, stiffener 620 is a long reinforcing member extending in the Y direction, and the length of stiffener 620 is optional depending on the number of connected end restraint members 300. In the example shown in Fig. 5, long stiffener 620 is provided on the top surface (XY plane) of one end restraint member 300 (300a) and another end restraint member 300 (300a).

[0076] The long stiffener 620, the end restraint member 300 (300a), and the other end restraint member 300 (300a) have holes (through holes) formed therein through which the fastening member 460 can pass. The long stiffener 620, the end restraint member 300, and the other end restraint member 300 (300a) are fastened together in the vertical direction (Z direction) by the fastening member 460, and connected to the case 400, thereby connecting one end restraint member 300 (300a) and the other end restraint member 300 (300a).

[0077] Note that, in the end restraint members 300 (300b) on the other end side of the battery module 110, the adjacent end restraint members 300 (300b) can be similarly connected to each other using the same connecting structure example 2.

[0078] In connection structure example 2, the battery module 110, which is held in the XZ plane by the side restraint members 200 (200a, 200b), is held (connected) to the case 400 via the side restraint members 200 (200a, 200b) and the end restraint members 300 (300a, 300b).

[0079] <Connection structure example 3> Fig. 6 is a diagram showing a third example of a connecting structure for connecting end restraint members 300 according to the embodiment. In the third example of a connecting structure, a connecting structure using a stiffener 630 will be described. As with the first example of a connecting structure, the example in Fig. 6 will be described assuming that one end restraint member 300 (300a) is connected to another end restraint member 300 (300a).

[0080] In connection structure example 3, one side restraint member 200 (200a) in one battery module 110 is connected to (contacts) one end restraint member 300 (300a). Further, another side restraint member 200 (200b) in another adjacent battery module 110 is connected to (contacts) another end restraint member 300 (300a).

[0081] As shown in Figure 6, one side restraint member 200 (200a) has a flange 232 (first flange) formed in the Y direction (Y+ direction) at the end of the side restraint member 200, and one end restraint member 300 (300a) has a step 332 (first step) that can be connected (abut) with the flange 232.

[0082] In addition, the other side restraint member 200 (200a) has a flange 231 (second flange) formed in the Y direction (Y-direction) at the end of the side restraint member 200, and the other end restraint member 300 (300a) has a step 331 (second step) that can be connected (abut) with the flange 231.

[0083] The steps 331 and 332 are formed with a threaded portion 631 (for example, a male screw) that threadably engages with a fastening member 632 (for example, a fastening nut).

[0084] As shown in FIG. 6, the stiffener 630 is a reinforcing member that reinforces the YZ surface of the end restraint member 300 (300a).

[0085] The stiffener 630, the flange 231, and the flange 232 have holes (through holes) formed therein that can pass through the threaded portions 631 formed in the steps 331, 332. The stiffener 630, the flange 231, and the flange 232 are fastened together to the steps 331, 332 by the fastening member 632, thereby connecting one end restraint member 300 (300a) to the other end restraint member 300 (300a).

[0086] Note that, in the end restraint members 300 (300b) on the other end side of the battery module 110, the adjacent end restraint members 300 (300b) can be similarly connected to each other using the same connecting structure example 3.

[0087] In connection structure example 3, the battery module 110, which is held in the XZ plane by the side restraint members 200 (200a, 200b), is held (connected) to the case 400 via the side restraint members 200 (200a, 200b) and the end restraint members 300 (300a, 300b).

[0088] <Battery cell> 7 is a diagram showing a cross-sectional structure (XZ cross section) of the battery cell 100. The battery cell 100 (secondary battery) may be an all-solid-state battery.

[0089] In the coordinate system in the drawing, the X axis indicates the longitudinal direction of the battery cell 100 (extension direction of the lead tab), and the Z axis indicates the thickness direction of the battery cell 100 (thickness direction of the electrode body 2).

[0090] The battery cell 100 includes an electrode body 2 (also referred to as a laminate in this embodiment) which is an energy storage element formed by stacking a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, an exterior member 18 which seals the periphery of the housed electrode body 2, lead tabs 13 and 14, and current collecting tabs 15 and 16.

[0091] The electrode body 2 has a two-layer structure of a positive electrode layer and a negative electrode layer. The positive electrode layer has two positive electrode layers 21 and 23, and the negative electrode layer has two negative electrode layers 22 and 24. A solid electrolyte layer 25 is provided between the positive electrode layer 21 and the negative electrode layer 22. A solid electrolyte layer 25 is also provided between the positive electrode layer 23 and the negative electrode layer 24. The positive electrode layer and the negative electrode layer may be single-phase (one-phase) or may be composed of multiple layers. When multiple positive electrode layers and multiple negative electrode layers are provided, a solid electrolyte layer is provided between each positive electrode layer and negative electrode layer, as shown in FIG. 7. The example in FIG. 7 illustrates a two-layer structure of positive electrode layers and negative electrode layers, but the present invention is not limited to this example, and the positive electrode layers and negative electrode layers may have three or more layers.

[0092] The positive electrode layers 21 and 23 each have a positive electrode active material layer 711 and a positive electrode current collector 712. The positive electrode current collector 712 is common to the two positive electrode layers 21 and 23. The positive electrode current collector 712 is disposed at the center in the thickness direction (Z direction) of the electrode body 2, and the positive electrode active material layer 711 of the positive electrode layer 21 and the positive electrode active material layer 711 of the positive electrode layer 23 are laminated on the upper and lower sides of the positive electrode current collector 712.

[0093] The negative electrode layer 22 is disposed (stacked) on the upper surface side of the positive electrode layer 21 in the thickness direction (Z direction) of the electrode body 2, and the negative electrode layer 24 is disposed (stacked) on the lower surface side of the positive electrode layer 23 in the thickness direction (Z direction) of the electrode body 2. The negative electrode layers 22 and 24 are stacked so as to sandwich the positive electrode layers 21 and 23. The negative electrode layers 22 and 24 each have a negative electrode active material layer 721 and a negative electrode current collector 722. The two negative electrode current collectors 722 are each formed in a layered form on the outermost layers of the electrode body 2. The configuration of the positive electrode layer and the negative electrode layer is not limited to the stacking order shown in FIG. 7, and they may be stacked so that two positive electrode layers sandwich two negative electrode layers.

[0094] The active material constituting the positive electrode active material layer 711 may be an NCM-based (ternary active material) mixture of cobalt, nickel, and manganese, such as lithium cobalt oxide, lithium nickel oxide, or lithium manganese oxide.

[0095] Examples of the active material constituting the negative electrode active material layer 721 include lithium-based materials and silicon-based materials. Other examples of the material constituting the negative electrode active material layer 721 include carbon materials such as graphite, soft carbon, and hard carbon, tin-based materials, and transition metal oxides (for example, lithium titanate: LTO).

[0096] The solid electrolyte layer 25 is made of, for example, a solid electrolyte having ionic conductivity, and examples of the material include a sulfide-based solid electrolyte material, an oxide-based solid electrolyte material, a nitride-based solid electrolyte material, and a halide-based solid electrolyte material.

[0097] The positive electrode current collector 712 and the negative electrode current collector 722 are made of, for example, a metal foil, a metal sheet, or a metal plate made of aluminum, copper, SUS, or the like. The positive electrode active material layer 711, the negative electrode active material layer 721, and the solid electrolyte layer 25 may be formed by binding particles of the materials that make them up with an organic polymer compound binder. The positive electrode active material layer 711 or the negative electrode active material layer 721 may contain an electronic conductive additive such as carbon (particles or fibers) or metal powder. A solid electrolyte powder may also be disposed in the positive electrode active material layer 711 or the negative electrode active material layer 721 to establish an ion conductive path.

[0098] The exterior member 18 is a container that houses the electrode assembly 2. The exterior member 18 is formed by folding a single sheet-like material in two, or by bonding multiple sheets of sheet-like material together. The material of the exterior member 18 is formed, for example, by covering the front and back surfaces of a metal layer with an insulating layer.

[0099] One end of the lead tab 13 is located outside the exterior member 18, and the other end is located inside the exterior member 18. The other end of the lead tab 13 is connected to the positive electrode current collector 712 inside the exterior member 18 via a current collecting tab 15, and the lead tab 13 forms a tab for the positive electrode. The lead tab 13 and the current collecting tab 15 are formed, for example, from a conductive metal sheet or metal plate.

[0100] One end of the lead tab 14 is located outside the exterior member 18, and the other end is located inside the exterior member 18. The other end of the lead tab 14 is connected to the negative electrode current collector 722 inside the exterior member 18 via a current collecting tab 16, and the lead tab 14 forms a tab for the negative electrode. The lead tab 14 and the current collecting tab 16 are formed, for example, from a conductive metal sheet or metal plate. The electrode body 2 can be charged or discharged by connecting the lead tabs 13 and 14 to a charger or an electrical load.

[0101] [Embodiment 2] In the second embodiment, a structure for preventing thermal chain reaction (hereinafter referred to as thermal chain reaction prevention structure) in the battery pack 500 described in the previous embodiment will be described. Fig. 8 is a diagram illustrating the thermal chain reaction prevention structure of the battery pack 500 according to the second embodiment. Fig. 8 shows a YZ cross section of the battery pack 500. Focusing on one battery module 110 among the battery module group 115, the battery module 110 arranged adjacent to this battery module 110 in the Y direction is shown.

[0102] 8 shows a state in which the battery module 110 (laminated body 111) is placed in the case 400 and covered from above with a cover 410, but this also shows the arrangement of the battery cells 100 in the YZ cross section. The first surface 101 (101a, 101b) is a surface that is perpendicular to the lower surface 103 of the battery module 110 (laminated body 111) and is a surface that is along the lamination direction (direction perpendicular to the paper surface).

[0103] The side restraint members 200 (200a, 200b) face the first surfaces 101 (101a, 101b) of the battery modules 110 and extend in the stacking direction. The first surfaces 101 (101a, 101b) and the side restraint members 200 (200a, 200b) are joined by joining members 701 (FIG. 7).

[0104] A first distance (e.g., 810 in FIG. 8) between the upper ends of the side restraint members 200 (200a, 200b) and the cover 410 is shorter than a second distance 820 between the upper surface of the battery module 110 (stacked body 111, battery cells 100) and the cover 410. The side restraint members 200 (200a, 200b) and the battery module 110 (stacked body 111, battery cells 100) are formed so as to satisfy this positional relationship (first distance 810<second distance 820).

[0105] 8, for example, first distance 810 may be the distance when the upper ends of side restraint members 200 (200a, 200b) are in contact with cover 410. Alternatively, as long as the above positional relationship is satisfied, first distance 810 may be the distance when the upper ends of side restraint members 200 (200a, 200b) are separated from cover 410 by a predetermined gap in the Z direction (vertical direction).

[0106] In the case 400, a plurality of battery modules 110 are arranged in a direction (Y direction: intersecting direction) intersecting the XZ plane (first surface 101) of the stack 111. For example, as shown in Fig. 8, a side restraint member (e.g., 200 (200a)) is arranged to face another side restraint member (e.g., 200 (200b)) of another battery module 110 arranged adjacently in the case 400 in the intersecting direction.

[0107] The positional relationship between the first distance 810 and the second distance 820 (first distance 810<second distance 820) is similar for other side restraint members (200(200b)) in other adjacently arranged battery modules 110.

[0108] According to the thermal chain reaction prevention structure of the second embodiment, even when a battery cell 100 constituting the battery module 110 experiences thermal runaway, the flow of gas and ejected material emitted from that battery cell 100 is suppressed by the side restraint members 200. This makes it possible to prevent the ejected gas and ejected material from flowing toward other battery cells 100 that are arranged adjacent to the side restraint members 200 in the cross direction. The side restraint members 200 function as a firewall, and can suppress and prevent thermal chain reaction of the battery cells 100.

[0109] [Embodiment 3] In a third embodiment, another thermal chain reaction prevention structure in the battery pack 500 described in the previous embodiment will be described. FIG. 9 is a diagram illustrating the thermal chain reaction prevention structure of the battery pack 500 according to the third embodiment. FIG. 9 shows a YZ cross section of the battery pack 500. As in FIG. 8, attention is focused on one battery module 110 in the battery module group 115, and the battery module 110 arranged adjacent to this battery module 110 in the Y direction is shown. FIG. 9 shows a state in which the battery module 110 (laminated body 111) is arranged in the case 400 and is covered from above with a cover 410, but it also shows the arrangement of the battery cells 100 in the YZ cross section.

[0110] As in the second embodiment, the first surfaces 101 (101a, 101b) are surfaces that are perpendicular to the lower surfaces 103 of the battery modules 110 (stacked body 111) and extend along the stacking direction (perpendicular to the paper surface). The side restraint members 200 (200a, 200b) face the first surfaces 101 (101a, 101b) of the battery modules 110 and extend in the stacking direction. The first surfaces 101 (101a, 101b) and the side restraint members 200 (200a, 200b) are joined by joining members 701 (FIG. 7).

[0111] In other thermal chain reaction prevention structures in embodiment 3, similarly to embodiment 2, the side restraint members 200 (200a, 200b) and the battery module 110 (stacked body 111, battery cells 100) may be formed so as to satisfy the positional relationship between the first distance 810 and the second distance 820 (first distance 810<second distance 820). That is, the first distance 810 between the upper end of the side restraint member 200 (200a, 200b) and the cover 410 may be shorter than the second distance 820 between the upper surface of the battery module 110 (stacked body 111) and the cover 410.

[0112] 9, first distance 810 shows a state in which the upper ends of side restraint members 200 (200a, 200b) and cover 410 are separated by a predetermined gap, but cover 410 may be formed so that the predetermined gap is labyrinth-shaped. Also, first distance 810 may be the distance in a state in which the upper ends of side restraint members 200 (200a, 200b) and cover 410 are in contact with each other, as shown in FIG.

[0113] Within the case 400, a plurality of battery modules 110 are arranged in a direction (Y direction: intersecting direction) intersecting the XZ plane (first surface 101) of the stack 111. For example, as shown in Fig. 9, a side restraint member (e.g., 200 (200a)) is arranged to face another side restraint member (e.g., 200 (200b)) of another battery module 110 arranged adjacently within the case 400 in the intersecting direction. The positional relationship between the first distance 810 and the second distance 820 is also the same for the other side restraint member (200 (200b)) of the other adjacent battery module 110.

[0114] 9, the cover 410 is formed with a plurality of protrusions 415 extending downward toward the battery module 110 (the stack 111, the battery cells 100) at positions spaced apart along the Y direction. For example, if the cover 410 is made of a flame-retardant resin, the plurality of protrusions 415 can be molded integrally with the cover 410. Also, if the cover 410 is formed by press molding a metal plate, the plurality of protrusions 415 can be formed separately and attached to the cover 410 by welding or the like.

[0115] The side restraint member 200 (200a) on the left side of the paper surface shown in Fig. 9 and the other side restraint member 200 (200b) of the other battery cell 100 arranged adjacently in the transverse direction are positioned between the multiple protrusions 415. Similarly, the side restraint member 200 (200b) on the right side of the paper surface shown in Fig. 9 and the other side restraint member 200 (200a) of the other battery cell 100 arranged adjacently in the transverse direction are positioned between the multiple protrusions 415.

[0116] The lower ends 416 of the multiple protrusions 415 are extended so as to be closer to the battery module 110 (stack 111, battery cells 100) than the upper ends 910 of the side restraint members 200 (200a, 200b) and the upper ends 920 of the other side restraint members 200 (200b, 200a). The side restraint members 200 (200a, 200b), the multiple protrusions 415, and the battery module 110 (stack 111, battery cells 100) are formed to satisfy this positional relationship.

[0117] The positional relationship in the Y direction (transverse direction) between the side restraint members 200 (200a, 200b) positioned between the multiple protrusions 415 and the multiple protrusions 415 may be such that they are spaced apart at a predetermined gap, as shown in Fig. 9. When the side restraint member 200 and the other side restraint members 200 are positioned between the multiple protrusions 415, the side restraint member 200 and the other side restraint members 200 are positioned at a distance from the multiple protrusions 415 in the Y direction (transverse direction). The multiple protrusions 415 may be formed so that the predetermined gap in the Y direction (transverse direction) forms a labyrinth shape.

[0118] 9, the positional relationship in the Y direction (intersecting direction) between the side restraint member 200 and the multiple protrusions 415 may be in an abutting state. With the side restraint member 200 and the other side restraint members 200 positioned between the multiple protrusions 415, the side restraint member 200 and the other side restraint members 200 may be positioned in abutting contact with the multiple protrusions 415 in the Y direction (intersecting direction).

[0119] According to the thermal chain reaction prevention structure of the third embodiment, even when a battery cell 100 constituting the battery module 110 experiences thermal runaway, the flow of gas and ejected material emitted from that battery cell 100 is suppressed by the side restraint members 200. This makes it possible to prevent the ejected gas and ejected material from flowing toward other battery cells 100 arranged adjacent to the side restraint members 200 in the cross direction. The side restraint members 200 function as a firewall, and can suppress and prevent thermal chain reaction of the battery cells 100.

[0120] <Summary of the embodiment> The above embodiments disclose at least the following battery packs.

[0121] (Item 1) The battery pack of the above embodiment is a battery pack (500) having a case (400), a battery module (110) disposed in the case, and a cover (410) covering the top of the battery module, The battery module (110) a stack (111) in which a plurality of secondary batteries are stacked; a side restraining member (200) facing the first surface (101) of the stack and extending in the stacking direction of the stack, the first surface (101) is a surface that is perpendicular to the lower surface (103) of the stack and is a surface that is aligned along the stacking direction; A first distance (810) between the top end of the side restraining member and the cover is shorter than a second distance (820) between the top surface of the stack and the cover.

[0122] According to the battery pack of item 1, it is possible to provide a battery pack that can suppress thermal chain reactions when a battery cell experiences thermal runaway in a battery module that can improve mounting efficiency while suppressing an increase in the weight of the battery module.

[0123] (Item 2) The first distance (810) is the distance when the upper end of the side restraint member and the cover are in contact with each other, or the distance when the upper end and the cover are spaced apart in the vertical direction.

[0124] According to the battery pack of item 2, even when a battery cell 100 constituting the battery module 110 experiences thermal runaway, the flow of gas and ejected material emitted from that battery cell 100 is suppressed by the side restraint members 200. This makes it possible to prevent the ejected gas and ejected material from flowing toward other battery cells 100 arranged adjacent to the side restraint members 200 in the cross direction. The side restraint members 200 function as a firewall, suppressing and preventing thermal chain reactions among the battery cells 100.

[0125] (Item 3) The first surface (101) and the side restraint member (200) are joined by a joining member.

[0126] According to the battery pack of item 3, the functions that were performed by the cross member of the housing (case) and the functions that were performed by the bind bar in the prior art can be consolidated into the side restraint member 200 (200a, 200b) in the battery module 110 and battery module group 115 of this embodiment.

[0127] (Item 4) The battery module (110) A plurality of the laminated bodies are arranged in a cross direction (Y direction) that crosses the first surface (XZ surface), The side restraint member (200) is The battery module is disposed so as to face, in the intersecting direction, another side restraint member of another battery module disposed adjacently within the case.

[0128] According to the battery pack of item 4, the functions performed by the cross members of the housing (case) and the functions performed by the bind bars in the conventional technology can be integrated into the side restraint members 200 (200a, 200b) in the battery module 110 and battery module group 115 of this embodiment. By integrating the functions of the structural members, it is possible to provide a battery pack 500 that can improve the mounting efficiency of the battery modules 110 within the case 400.

[0129] (Item 5) The cover (410) has a plurality of protrusions (415) extending downward toward the battery module at positions spaced apart along the intersecting direction, The side restraint member (200) and the other side restraint member (200) are positioned between the plurality of protrusions (415).

[0130] (Item 6) The lower ends (416) of the plurality of protrusions are extended so as to be closer to the battery module (110) than the upper ends (910a, 910b) of the side restraint members and the other side restraint members.

[0131] (Item 7) When positioned between the plurality of protrusions (415), the side restraint member (200) and the other side restraint member (200) are arranged at a position spaced apart from the plurality of protrusions (415) in the cross direction.

[0132] (Item 8) When positioned between the plurality of protrusions (415), the side restraint member (200) and the other side restraint member (200) are arranged in a position abutting the plurality of protrusions (415) in the cross direction.

[0133] According to the battery pack of items 5 to 8, even when a battery cell 100 constituting the battery module 110 experiences thermal runaway, the flow of gas and ejected material emitted from that battery cell 100 is suppressed by the side restraint members 200. This makes it possible to prevent the ejected gas and ejected material from flowing toward other battery cells 100 arranged adjacent to the side restraint members 200 in the cross direction. The side restraint members 200 function as a firewall, suppressing and preventing thermal chain reactions among the battery cells 100.

[0134] The present invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0135] 100: battery cell (secondary battery), 110: laminate, 200: side restraint member, 231: flange, 232: flange, 300: end restraint member, 310: long end restraint member, 331: step, 332: step, 400: case (battery case), 410: cover, 415: protrusion, 450: frame, 455: reinforcing part, 500: battery pack

Claims

1. A battery pack having a case, a battery module disposed in the case, and a cover covering an upper portion of the battery module, The battery module includes: a stacked body in which a plurality of secondary batteries are stacked; a side restraint member facing the first surface of the stack and extending in the stacking direction of the stack, the first surface is a surface that is perpendicular to a lower surface of the stack and that is aligned along the stacking direction, a first distance between an upper end of the side restraint member and the cover is shorter than a second distance between an upper surface of the stack and the cover; The battery module includes: a plurality of the laminated bodies are arranged in a direction intersecting the first surface of the laminated body, The side restraint member is the battery module is disposed in a state facing in the intersecting direction another side restraint member of another battery module disposed adjacently in the case, the cover has a plurality of protrusions extending downward toward the battery module at positions spaced apart along the intersecting direction, The battery pack is characterized in that the side restraint member and the other side restraint member are positioned between the plurality of protrusions.

2. 2. The battery pack according to claim 1, wherein the first distance is a distance when the upper end of the side restraint member and the cover are in contact with each other, or a distance when the upper end and the cover are spaced apart in the vertical direction.

3. The battery pack according to claim 1 , wherein the first surface and the side restraint member are joined by a joining member.

4. 2. The battery pack according to claim 1, wherein the lower ends of the plurality of protrusions are extended so as to be closer to the battery module than the upper ends of the side restraint member and the other side restraint member.

5. 5. The battery pack according to claim 1, wherein when positioned between the plurality of protrusions, the side restraint member and the other side restraint member are positioned at a position spaced apart from the plurality of protrusions in the intersecting direction.

6. The battery pack according to claim 1 or 4, characterized in that, when positioned between the plurality of protrusions, the side restraint member and the other side restraint member are positioned in a position abutting the plurality of protrusions in the intersecting direction.

Images