Battery pack

Abstract

The invention provides a battery pack. Each of a plurality of battery cells (100) constituting a battery pack includes a case (120) that houses an electrode body (150), and has a substantially rectangular shape in which, when viewed from a first direction, a second direction orthogonal to the first direction is a long-side direction, and a third direction orthogonal to the first direction and the second direction is a short-side direction. The restraining member (400) includes a pair of members provided so as to sandwich the plurality of battery cells (100) in the third direction, and the pair of members are fixed to the end plate (200) from the third direction.

Description

Technical Field

[0001] This technology relates to battery packs. Background Technology

[0002] Previously, it was known that battery packs were constructed by arranging multiple battery cells along the stacking direction and using end plates and constraint components to constrain them in the stacking direction.

[0003] As a constraint structure for batteries in existing battery packs, examples of constraint structures described in International Publication Nos. 2019 / 130936 and 2019 / 130937 can be cited.

[0004] When expansion forces are generated within a single battery cell, bending moments act on end plates located at the ends of multiple cells. As battery cells become larger, the end plates require sufficient yield strength to withstand the increased moment loads. On the other hand, from the perspective of miniaturizing battery packs, the thickness of the end plates needs to be reduced. From the perspective of balancing these issues, there is still room for improvement in existing battery packs. Summary of the Invention

[0005] The purpose of this technology is to provide a battery pack that suppresses excessive increase in torque load acting on the end plates.

[0006] This technology provides the following battery packs. [1]

[0008] A battery pack includes: a plurality of battery cells arranged in a first direction; an end plate disposed at the end of the plurality of battery cells in the first direction; and a constraint member constraining the end plate and the plurality of battery cells in the first direction. Each of the plurality of battery cells includes a housing that houses electrodes. When viewed from the first direction, the housing has a generally rectangular shape with a second direction orthogonal to the first direction as its long side and a third direction orthogonal to both the first and second directions as its short side. The constraint member includes a pair of members disposed to clamp the plurality of battery cells in the third direction, and the pair of members is fixed to the end plate from the third direction. [2]

[0010] In the battery pack described in [1], the plurality of battery cells have electrode terminals on the surface of the housing that is orthogonal to the third direction. [3]

[0012] In the battery pack described in [1], the plurality of battery cells have electrode terminals on the surface of the housing that is orthogonal to the second direction. [4]

[0014] In any of the battery packs described in [1] to [3], the end plate has a stepped portion on at least one side in the third direction, and the battery pack also includes a contact plate that is fixed to the constraint member and abuts against the stepped portion from the first direction. [5]

[0016] In any of the battery packs described in [1] to [4],

[0017] The aforementioned pair of components are each composed of plate-shaped parts. [6]

[0019] In any of the battery packs described in [1] to [5], when viewed from the third direction, the pair of components are respectively positioned at the center of the second direction containing the plurality of battery cells. [7]

[0021] In any of the battery packs described in [1] to [6], the dimensions of each of the above-mentioned pair of components in the second direction vary along the first direction.

[0022] The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0023] Figure 1 It is a 3D diagram of the batteries that make up the battery pack.

[0024] Figure 2 This is the front view of the battery involved in the variation example.

[0025] Figure 3 yes Figure 2 The image shows a 3D view of the battery.

[0026] Figure 4 This is a diagram showing the constrained structure of the batteries in a battery pack.

[0027] Figure 5 This is a diagram used to illustrate the loads acting on the end plate.

[0028] Figure 6 This is a diagram used to illustrate the relationship between the width (B) and height (H) of a battery.

[0029] Figure 7 This is a diagram showing an example of the shape of a constraint component in a battery pack. Detailed Implementation

[0030] The following describes the implementation of this technology. Sometimes the same or equivalent parts are labeled with the same reference numerals, and they are not described repeatedly.

[0031] Furthermore, in the embodiments described below, when numbers, quantities, etc., are mentioned, the scope of this technology is not necessarily limited to that number, quantity, etc., unless specifically stated otherwise. Additionally, in the embodiments described below, each constituent element is not necessarily essential to this technology unless specifically stated otherwise. Furthermore, this technology is not limited to performing all the effects mentioned in this embodiment.

[0032] Furthermore, in this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a structure is included, other structures besides that structure may be included, or none may be included.

[0033] Furthermore, in this specification, when using geometric terms and terms indicating positional or directional relationships, such as "parallel," "orthogonal," "45° oblique," "coaxial," and "along," these terms allow for manufacturing errors or slight variations. In this specification, when using terms indicating relative positional relationships such as "upper side" and "lower side," these terms are used to indicate the relative positional relationship in one state, and the relative positional relationship can be reversed or rotated to any angle depending on the setting direction of each mechanism (e.g., reversing the overall vertical orientation of the mechanism).

[0034] In this specification, "battery" is not limited to lithium-ion batteries, but may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, the positive and negative electrodes are collectively referred to as "electrodes".

[0035] In this specification, "battery" can be used in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). However, the use of "cell batteries" is not limited to vehicle applications.

[0036] Figure 1 This is a 3D diagram of the batteries that make up the battery pack. For example... Figure 1 As shown, the battery 100 (cell battery) has a square shape. The battery 100 has electrode terminals 110, a frame 120, an vent valve 130, and a liquid filling hole 140. A battery pack is formed by arranging multiple batteries 100 along the Y-axis direction (first direction).

[0037] Electrode terminals 110 are formed on the frame 120. Electrode terminals 110 have positive terminals 111 and negative terminals 112 arranged along an X-axis direction (second direction) orthogonal to the Y-axis direction (first direction). Positive terminals 111 and negative terminals 112 are arranged separately from each other in the X-axis direction.

[0038] The frame 120 has a cuboid shape, forming the appearance of the battery 100. The frame 120 includes a housing for the electrode body 150 (see reference). Figure 4 The electrolyte housing 120A and the sealing plate 120B that seals the opening of the housing 120A are also included. The sealing plate 120B is joined to the housing 120A by welding.

[0039] The frame 120 has an upper surface 121, a lower surface 122, a first side 123, a second side 124 and two third side 125.

[0040] The upper surface 121 is a plane orthogonal to the Z-axis direction (the third direction), which is orthogonal to both the Y-axis and X-axis directions. Electrode terminals 110 are disposed on the upper surface 121. That is, in Figure 1 In the exemplified battery 100, electrode terminals 110 are provided on a surface of the frame 120 orthogonal to the Z-axis direction (third direction). The lower surface 122 is opposite to the upper surface 121 along the Z-axis direction.

[0041] Each side of the first side 123 and the second side 124 is formed by a plane orthogonal to the Y-axis. Each side of the first side 123 and the second side 124 has the largest area among the multiple sides of the frame 120. When viewed from the Y-axis direction, each side of the first side 123 and the second side 124 has a roughly rectangular shape with the X-axis as the longer side and the Z-axis as the shorter side.

[0042] In one example of assembling a battery pack, adjacent batteries 100 in the Y-axis direction are stacked with their first side 123 facing each other and their second side 124 facing each other. Thus, in the Y-axis direction where multiple batteries 100 are stacked, the positive terminal 111 and the negative terminal 112 are arranged alternately.

[0043] An exhaust valve 130 is provided on the upper surface 121. When the temperature of the battery 100 rises (thermal runaway) and the internal pressure of the frame 120 exceeds a predetermined value due to the gas generated inside the frame 120, the exhaust valve 130 discharges the gas to the outside of the frame 120.

[0044] An injection port 140 is provided on the upper surface 121. Electrolyte is injected into the interior of the frame 120 through the injection port 140. The injection port 140 is sealed by a sealing member. For example, blind rivets and other metal components can be used as sealing members.

[0045] The positions of the vent valve 130 and the injection port 140 are not limited to Figure 1 As shown, it can be changed appropriately.

[0046] Figure 2 This is a front view of the battery 100 involved in the modified example. Figure 3 yes Figure 2 A 3D view of battery 100 is shown. Figure 2 , Figure 3 The battery 100 shown has electrode terminals 110, a frame 120, and a liquid injection hole 140. A battery pack is formed by arranging the batteries 100 along the Y-axis direction (first direction). The frame 120 includes a housing body 120A, a sealing plate 120B (first sealing plate), and a sealing plate 120C (second sealing plate). A battery pack is formed by arranging multiple batteries 100 along the Y-axis direction (first direction).

[0047] The main body 120A of the casing is composed of a cylindrical, and preferably square, component. As a result, a square battery 100 can be obtained.

[0048] like Figure 2 , Figure 3 As shown, sealing plates 120B and 120C are respectively provided at both ends of the housing body 120A. The housing body 120A is constructed, for example, by having the end edges of bent plate-shaped components abut against each other. Figure 3 The exemplified joint 120D) can be joined together (e.g., by laser welding) to form a square tube shape. The corners of the "square tube" can also have an R shape.

[0049] Figure 2 , Figure 3 The sealing plates 120B and 120C shown have a generally rectangular shape with the Y-axis as the short side and the Z-axis as the long side. A generally rectangular shape includes a rectangular shape, or a rectangular shape with its corners rounded (R-shaped), etc., that is essentially a rectangle.

[0050] A positive terminal 111 is provided on the sealing plate 120B. A negative terminal 112 and an injection hole 140 are provided on the sealing plate 120C. That is, in Figure 2 , Figure 3 In the illustrated battery 100, electrode terminals 110 are provided on a surface of the housing 120 orthogonal to the X-axis direction (second direction). The positions of the positive terminal 111, the negative terminal 112, and the liquid injection hole 140 can be appropriately changed.

[0051] exist Figures 1-3 In the battery 100 shown, the main body 120A and the sealing plates 120B and 120C are made of metal. Specifically, the main body 120A and the sealing plates 120B and 120C are made of aluminum, aluminum alloy, iron or iron alloy, etc.

[0052] exist Figures 1-3 In the battery 100 shown, the casing body 120A is formed to be longer in the width direction (X-axis direction) than in the thickness direction (Y-axis direction) and height direction (Z-axis direction) of the battery 100. That is, when the battery 100 is viewed from the Y-axis direction, the frame 120 (casing) of the battery 100 has a generally rectangular shape in which the X-axis direction (second direction) is the long side and the Z-axis direction (third direction) is the short side.

[0053] Figure 4 This is a diagram illustrating the constraint structure of the battery 100 in the battery pack according to this embodiment. Furthermore, in the example shown in the diagram, [the following is unclear and likely incomplete: "for..."] Figure 1 The battery 100 shown is an example, but... Figure 2 , Figure 3 In the case of the battery 100 shown, it can also be applied to Figure 4 The constraint shown is the same as the constraint structure.

[0054] like Figure 4 As shown, the battery pack includes a battery 100, an end plate 200, a separator 300, a restraint component 400, a contact plate 500, and bolts 600.

[0055] End plate 200 is disposed at the end of a plurality of batteries 100 in the Y-axis direction (first direction). When viewed from the Y-axis direction, end plate 200 has a generally rectangular shape in which the X-axis direction (second direction) is the long side direction and the Z-axis direction (third direction) is the short side direction.

[0056] An insulating diaphragm 300 is provided between the end plate 200 and the battery 100. The diaphragm 300 is also provided between the multiple batteries 100. A constraint member 400 constrains the end plate 200 and the multiple batteries 100 in the Y-axis direction.

[0057] The constraint member 400 includes a pair of plate-shaped members. For example... Figure 4 As shown, a pair of plate-shaped components are arranged to clamp multiple batteries 100 in the Z-axis direction. A contact plate 500 is fixed to the constraint component 400. The constraint component 400 and the contact plate 500 are fixed to the end plate 200 in the Z-axis direction by bolts 600.

[0058] The end plate 200 has stepped portions 210 on both sides in the Z-axis direction. The contact plate 500 abuts against the stepped portions 210 from the Y-axis direction. When a battery pack is formed, multiple batteries 100 are held in a state where they are compressed by the end plate 200 together with the separator 300 in the Y-axis direction. As a reaction, the reaction force from the battery 100 (cell reaction force) acts on the end plate 200.

[0059] When an expansion force is generated in the battery 100, the force (cell reaction force) from the battery 100 in the Y-axis direction increases due to this expansion force. The cell reaction force is transmitted to the restraint member 400 via the stepped portion 210 of the end plate 200 and the contact plate 500. As a reaction, a compressive force in the Y-axis direction is applied to the battery 100, which suppresses the expansion of the battery 100.

[0060] By providing the contact plate 500, the force (cell reaction force) from the battery 100 in the Y-axis direction can be transformed into shear stress for support. Furthermore, by providing a hole in the constraint member 400, the contact plate 500 can be fitted into the hole, thereby increasing the connection strength between the constraint member 400 and the contact plate 500.

[0061] Figure 5 This is a diagram used to illustrate the load acting on the end plate 200. As described above, the end plate 200 is connected to the constraint member 400 at both ends in the Z-axis direction via contact plates 500 to restrict displacement in the Y-axis direction.

[0062] like Figure 5 As shown, the load in the Y-axis direction is applied from the battery 100 to the end plate 200. For the two ends in the Z-axis direction of the end plate 200, since the displacement in the Y-axis direction is restricted, this part is schematically regarded as two fulcrums, and the interval between them can be defined as the distance between the fulcrums (L).

[0063] like Figure 5 As shown, assuming the reaction force of the battery cell is a uniformly distributed load (w) for modeling, the maximum value (δmax) of the deflection of the end plate 200 due to the reaction force of the battery cell is:

[0064] δmax=5wL 4 / 384EI

[0065] (w: distributed load, L: distance between supports, E: Young's modulus, I: moment of inertia of section), which is proportional to the fourth power of the distance between supports (L).

[0066] As described above, the end plate 200 has the function of suppressing the deformation of the battery 100. It is necessary to suppress the expansion of the battery 100 by means of the end plate 200 to reduce the deformation of the frame 120.

[0067] In this embodiment, when viewed from the Y-axis direction, the end plate 200 is connected to the constraint member 400 at both ends of the Z-axis direction, which is the short side of the battery 100. Therefore, compared with the structure in which the end plate 200 is connected to the constraint member 400 at both ends of the X-axis direction, which is the long side, the size of the battery 100 can be reduced. Figure 5 The distance (L) between the pivots is shown.

[0068] Therefore, in this embodiment, if the distributed load (w) from the battery, as well as the Young's modulus (E) and moment of inertia (I) of the end plate 200 are constant, the maximum value (δmax) of the deflection (deformation) caused by the reaction force of the battery cell can be reduced.

[0069] In other words, in this embodiment, if the allowable deformation of the end plate 200 is constant, even under a relatively small moment of inertia (I) of the cross section, the deformation under a specified distributed load (w) can still meet the condition of allowable deformation.

[0070] The inventors of this application have confirmed that, under specific conditions, when subjected to the same reaction force from a single battery cell, the thickness of the end plate 200 required to meet the allowable deformation conditions can be reduced to less than 1 / 3 (approximately 60 mm thickness can be reduced to approximately 19 mm) when the end plate 200 is supported at both ends in the short side direction (Z-axis direction) compared to when the end plate 200 is supported at both ends in the long side direction (X-axis direction). By making the end plate 200 thinner and lighter, it is possible to achieve miniaturization or weight reduction of the battery pack.

[0071] In the battery pack of this embodiment, by constraining the end plate 200 on the long side (the sides at both ends in the Z-axis direction) of the battery pack, rather than on the short side (the sides at both ends in the X-axis direction), it is possible to suppress the excessive increase of the deflection of the end plate 200 even when an expansion force is generated in the battery 100.

[0072] Figure 6 This is a diagram used to illustrate the relationship between the width (B) and height (H) of battery 100. For example... Figure 6 As shown, the battery 100 constituting the battery pack according to this embodiment has a generally rectangular shape in which the width (B) in the X-axis direction is greater than the height (H) in the Z-axis direction. In other words, the frame 120 of the battery 100 has a generally rectangular shape in which the X-axis direction is the long side direction and the Z-axis direction is the short side direction.

[0073] The width (B) of the frame 120 in the X-axis direction is preferably 200 mm or more, more preferably 300 mm or more, and even more preferably 500 mm or more. The width (B) of the frame 120 in the X-axis direction is preferably 1200 mm or less. By making the width (B) of the frame 120 in the X-axis direction within the above range, a relatively large (high-capacity) battery 100 can be constructed.

[0074] The Z-axis dimension (height: H) of the frame 120 is preferably 200 mm or less, more preferably 150 mm or less, and even more preferably 100 mm or less. In one example, it is about 90 mm. By making the Z-axis dimension (height: H) of the frame 120 within the above range, a battery 100 with a relatively low height can be constructed, which can improve, for example, vehicle mounting capability.

[0075] The ratio of the dimension in the X-axis direction to the dimension in the Z-axis direction of the frame 120 (width / height: B / H) is preferably 2 or more, more preferably 3 or more, and even more preferably 5 or more. The ratio of the dimension in the X-axis direction to the dimension in the Z-axis direction of the frame 120 (width / height: B / H) is 12 or less.

[0076] The end plate 200 preferably has dimensions that allow it to abut against the entire area of ​​the first side 123 and the second side 124 of the frame 120. The ratio of the dimension of the end plate 200 in the X-axis direction to its dimension in the Z-axis direction may be approximately the same as, or different from, the ratio of the dimension of the frame 120 in the X-axis direction to its dimension in the Z-axis direction. Furthermore, the dimensions (width: B, height: H) of the frame 120 and the end plate 200 are not limited to the numerical ranges described above.

[0077] Figure 7 This is a diagram showing an example of the shape of the constraint component 400. Figure 7 In the example shown, the constraint member 400 includes a first portion 410 with a relatively wide width in the X-axis direction, a second portion 420 with a varying width in the X-axis direction, and a third portion 430 with a relatively narrow width in the X-axis direction. The first portion 410, the second portion 420, and the third portion 430 are arranged from the end of the battery pack in the Y-axis direction toward the center. That is, the dimension of the constraint member 400 in the X-axis direction varies along the Y-axis direction.

[0078] The first part 410 is fixed to the end plate 200. By configuring the wide first part 410, the cross-sectional rigidity of the constraint member 400 at the end of the battery pack can be increased. In addition, by providing a second part 420 between the first part 410 and the third part 430, which makes the width of the constraint member 400 continuously change, excessive stress concentration in the constraint member 400 can be suppressed.

[0079] like Figure 7 As shown, when viewed from the Z-axis direction (third direction), the constraint member 400 is preferably positioned at the center of the X-axis direction (second direction) containing the plurality of batteries 100. Furthermore, when viewed from the Z-axis direction (third direction), the constraint member 400 preferably has a line-symmetric shape about the Y-axis direction (first direction).

[0080] Embodiments of the present invention have been described, but the embodiments disclosed herein should be considered as illustrative in all respects and not restrictive. The scope of the invention is set forth in the claims and is intended to include all modifications of the same meaning and scope as the claims.

Claims

1. A battery pack, characterized in that, have: Multiple battery cells arranged in a first direction; An end plate, which is disposed at the end of the plurality of battery cells in the first direction; and A constraint component that constrains the end plate and the plurality of battery cells in the first direction. Each of the plurality of battery cells includes a housing, which houses the electrode body. When viewed from the first direction, the housing has a generally rectangular shape in which a second direction orthogonal to the first direction is the long side direction, and a third direction orthogonal to both the first and second directions is the short side direction. The constraint component includes a pair of components arranged to clamp the plurality of battery cells in the third direction. The pair of components are fixed to the end plate from the third direction.

2. The battery pack according to claim 1, characterized in that, The plurality of battery cells have electrode terminals on the surface of the housing orthogonal to the third direction.

3. The battery pack according to claim 1, characterized in that, The plurality of battery cells have electrode terminals on the surface of the housing orthogonal to the second direction.

4. The battery pack according to any one of claims 1 to 3, characterized in that, The end plate has a stepped portion on at least one side in the third direction. The battery pack also includes a contact plate that is fixed to the constraint member and abuts against the step portion from the first direction.

5. The battery pack according to any one of claims 1 to 3, characterized in that, The pair of components are each composed of plate-shaped components.

6. The battery pack according to any one of claims 1 to 3, characterized in that, When viewed from the third direction, the pair of components are respectively positioned at the center of the second direction containing the plurality of battery cells.

7. The battery pack according to any one of claims 1 to 3, characterized in that, The dimensions of each of the pair of components change along the first direction in the second direction.

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