To provide a battery stack, a power storage device, and a vehicle mounting structure.

Abstract

To provide a battery stack, a power storage device, and a vehicle mounting structure of the power storage device capable of suppressing deformation of a battery cell when an external force is input.SOLUTION: The battery stack 40 includes a plurality of battery cells 50 disposed side by side on the W1 in the first direction, and at least one inter-cell member 60 disposed between the adjacent battery cells 50. The exterior member 53 includes the low-rigidity portion W1 overlapping the first direction 53B and the high-rigidity portion 53A having higher rigidity than the low-rigidity portion 53B and provided on the end side of the low-rigidity portion 52B in the second direction W1 intersecting the first direction W2, and the inter-cell member 60 includes the first portion 61 in contact with the high-rigidity portion 53B and the second portion 62 in contact with the low-rigidity portion 53A.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a battery stack, an electricity storage device, and a vehicle mounting structure. [Background technology]

[0002] Patent Document 1 describes a battery (battery cell) in which a battery element is housed in an exterior portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-084066 Summary of the Invention [Problem to be solved by the invention]

[0004] It is known that the electrode bodies of battery cells expand and contract during charging and discharging. For this reason, in a battery stack in which single battery cells are stacked in one direction and electrically connected to each other, an inter-cell member is placed between two adjacent battery cells as a buffer material, for example.

[0005] These inter-cell members are generally arranged in the exterior member of the battery cell so as to overlap with the electrode body in the stacking direction, and are not usually arranged at the end side of the exterior member. In other words, the end side of the exterior member is a portion that is not restricted by contact with the inter-cell member.

[0006] Meanwhile, in the manufacturing process of a battery stack, an external force in a predetermined direction may be applied to a stack of battery cells and inter-cell members when stacking the battery cells or welding terminal members. Furthermore, in a battery stack installed as a driving source for a vehicle, an external force may be applied to the stack due to vibrations during driving. In such cases, stress may be concentrated in areas of the exterior member with low rigidity, potentially deforming the battery cells.

[0007] For example, the rigidity of the exterior material of a battery cell in the portion that overlaps with the electrode body in the stacking direction is often relatively low compared to the rigidity of the end portion where connection is made to terminal members, etc. For this reason, stress may concentrate in the low-rigidity portion of the exterior material at the boundary with the high-rigidity portion of the exterior material that is not restrained by the inter-cell member, potentially causing deformation of the battery cell.

[0008] In consideration of the above, an object of the present invention is to provide a battery stack, a power storage device, and a vehicle mounting structure for a power storage device that can suppress deformation of battery cells when an external force is applied. [Means for solving the problem]

[0009] A battery stack according to a first aspect is a battery stack comprising: an electrode body housed in an exterior member; battery cells arranged in a row in a first direction; and at least one inter-cell member arranged between adjacent battery cells; wherein the exterior member includes a low-rigidity portion that overlaps with the electrode body in the first direction; and a high-rigidity portion that has higher rigidity than the low-rigidity portion and is provided on the end side of the low-rigidity portion in a second direction that intersects with the first direction; and the inter-cell member has a first portion that contacts the high-rigidity portion and a second portion that contacts the low-rigidity portion.

[0010] A battery stack according to a first aspect includes a plurality of battery cells arranged side by side in a first direction and at least one inter-cell member arranged between adjacent battery cells. Each battery cell has an electrode assembly housed in an exterior member. The exterior member includes a low-rigidity portion overlapping the electrode assembly in the first direction and a high-rigidity portion having higher rigidity than the low-rigidity portion and located on the end side of the low-rigidity portion in a second direction intersecting the first direction. The inter-cell member arranged between adjacent battery cells is generally arranged in a position corresponding to the low-rigidity portion of the exterior member that experiences a large amount of displacement due to expansion and contraction of the electrode assembly, and is not usually arranged at a position near the end of the exterior member. In other words, the end side of the exterior member is not constrained by contact with the inter-cell member. Therefore, when an external force is applied, stress concentrates in the low-rigidity portion at the boundary with the high-rigidity portion of the exterior member that is not constrained by the inter-cell member, potentially deforming the battery cell.

[0011] In a first aspect of the present invention, the inter-cell member has a first portion that contacts the high-rigidity portion and a second portion that contacts the low-rigidity portion. Therefore, the high-rigidity portion of the exterior member provided on the end side in the second direction contacts and is restrained by the inter-cell member. This restricts the position of the high-rigidity portion of the exterior member when an external force is applied, reducing stress concentration in the low-rigidity portion at the boundary between the high-rigidity portion and the low-rigidity portion of the exterior member, thereby suppressing deformation of the battery cells.

[0012] A battery stack according to a second aspect is the same as the first aspect, except that the low-rigidity portion is made of a laminate film.

[0013] In the battery stack according to the second aspect, as described above, stress concentration in the low-rigidity portion made of laminate film is suppressed. Therefore, deformation of the battery cell can be suppressed even when a laminate film is used as an exterior member that encases the electrode assembly. Furthermore, by configuring the low-rigidity portion with laminate film, it is easy to ensure insulation from the terminal member connected to the electrode assembly. As a result, it is possible to improve the heat dissipation of the battery cell by, for example, increasing the cross-sectional area of ​​the terminal member. This effectively suppresses temperature rise of the battery cell due to charging and discharging.

[0014] A battery stack according to a third aspect has the configuration described in the first or second aspect, wherein the frictional force between the high-rigidity portion and the first portion is greater than the frictional force between the low-rigidity portion and the second portion.

[0015] In the battery stack according to the third aspect, the frictional force generated at the contact area between the high-rigidity portion of the exterior member and the first portion of the inter-cell member is greater than the frictional force generated at the contact area between the low-rigidity portion and the second portion of the exterior member. As a result, the restraining force of the inter-cell member on the high-rigidity portion is increased relative to the restraining force on the low-rigidity portion, effectively suppressing deformation of the battery cells.

[0016] A battery stack according to a fourth aspect is the configuration according to the third aspect, wherein the coefficient of friction of the inter-cell member is greater in the first portion than in the second portion.

[0017] In the battery stack according to the fourth aspect, the friction coefficient of the first portion of the inter-cell member is greater than the friction coefficient of the second portion, so that the friction force generated at the contact portion between the high-rigidity portion of the exterior member and the first portion of the inter-cell member is greater than the friction force generated at the contact portion between the low-rigidity portion and the second portion.

[0018] A battery stack according to a fifth aspect has the configuration described in the third or fourth aspect, wherein the thickness of the inter-cell member in the first direction is such that the thickness of the first portion is greater than the thickness of the second portion.

[0019] In a battery stack according to a fifth aspect, the thickness of the inter-cell member in the first direction is such that the thickness of the first portion is greater than the thickness of the second portion. Therefore, the high-rigidity portion of the exterior member contacts the inter-cell member preferentially over the low-rigidity portion, and the normal force acting on the contact surface with the first portion is relatively greater than the normal force acting on the contact surface with the second portion. As a result, the frictional force acting on the contact portion between the high-rigidity portion of the exterior member and the first portion of the inter-cell member is greater than the frictional force acting on the contact portion between the low-rigidity portion and the second portion.

[0020] A battery stack according to a sixth aspect has the configuration described in any one of the third to fifth aspects, wherein the Young's modulus of the inter-cell member is greater in the first portion than in the second portion.

[0021] In a battery stack according to a sixth aspect, the Young's modulus of the first portion of the inter-cell member is greater than that of the second portion. This makes the high-rigidity portion of the exterior member more rigid than the low-rigidity portion, resulting in a relatively higher normal force acting from the contact surface with the inter-cell member. This makes the frictional force acting at the contact portion between the high-rigidity portion of the exterior member and the first portion of the inter-cell member greater than the frictional force acting at the contact portion between the low-rigidity portion of the exterior member and the second portion.

[0022] A battery stack according to a seventh aspect is the configuration according to the first or second aspect, wherein the first portion of the inter-cell member is fitted into the high-rigidity portion.

[0023] In a battery stack according to a seventh aspect, a first portion of the inter-cell member that comes into contact with the high-rigidity portion of the exterior member is fitted to the high-rigidity portion, thereby relatively increasing the restraining force of the lid body portion by the inter-cell member and effectively suppressing deformation of the battery cells.

[0024] A battery stack according to an eighth aspect is the same as the configuration according to any one of the first to seventh aspects, wherein the inter-cell member is a heat insulating member.

[0025] In the battery stack according to the eighth aspect, the battery cells can be thermally insulated by the inter-cell members, which makes it possible to prevent a heat chain reaction from spreading to adjacent battery cells when a battery cell generates abnormal heat.

[0026] A battery stack according to a ninth aspect is configured as described in any one of the first to eighth aspects, wherein the battery cells have a pair of the high-rigidity portions facing each other in a second direction that intersects with the first direction.

[0027] In a battery stack according to a ninth aspect, each battery cell has a pair of high-rigidity portions facing each other in a second direction intersecting with the first direction, which effectively prevents the high-rigidity portions from shifting in position in the second direction due to an external force input to the battery stack from the second direction.

[0028] A battery stack according to a tenth aspect is configured as described in the ninth aspect, wherein the pair of high-rigidity portions are electrically conductive.

[0029] In the battery stack according to the tenth aspect, the pair of high-rigidity portions provided on the exterior member are configured to be conductive, which allows the high-rigidity portions to be used as terminal members, thereby reducing the number of parts by configuring the high-rigidity portions and the terminal members as a single part.

[0030] The battery stack according to an eleventh aspect is configured as described in any one of the first to tenth aspects, and further comprises a pair of end plate portions arranged at one end in the first direction and the other end in the first direction.

[0031] A battery stack according to an eleventh aspect includes a pair of end plate portions disposed at one end of the battery stack in a first direction and the other end of the battery stack in the first direction. This allows a predetermined confining pressure to be applied in the first direction to a stack of battery cells and inter-cell members, stabilizing the confinement of the battery cells by the inter-cell members and effectively suppressing deformation of the battery cells.

[0032] The battery stack of the twelfth aspect, in the configuration described in the eleventh aspect, further includes a side plate portion arranged at at least one end in a direction perpendicular to the first direction, and the side plate portion connects the pair of end plate portions in the first direction.

[0033] In the battery stack according to the twelfth aspect, the pair of end plate portions are connected in the first direction by the side plate portions, so that the confinement pressure applied by the pair of end plate portions is more stable, and deformation of the battery cells is more effectively suppressed.

[0034] A battery stack according to a thirteenth aspect is configured as described in any one of the first to twelfth aspects, wherein the electrode assembly includes a solid electrolyte.

[0035] In a battery stack according to a thirteenth aspect, the electrode assembly includes a solid electrolyte, and the battery cells are so-called solid-state batteries. Therefore, the confining pressure applied to the stack of battery cells and inter-cell components can be increased compared to battery cells of liquid-based batteries. Therefore, the confining force on the battery cells in the first direction can be increased compared to a battery stack using battery cells of liquid-based batteries, and deformation of the battery cells can be effectively suppressed.

[0036] A fourteenth aspect of the present invention relates to a storage device comprising a battery stack according to any one of the first to thirteenth aspects, and further comprising a battery case that is arranged in line in the first direction and has at least two or more vertical wall portions extending in the second direction, and that houses the battery stack between adjacent vertical wall portions, and the battery stack is fixed to the vertical wall portions at one end in the first direction and at the other end in the first direction, either directly or via another member.

[0037] In a power storage device according to a fourteenth aspect, the battery stack is fixed inside the battery case via two vertical walls adjacent in a first direction. This power storage device can be applied to, for example, a vehicle with a CTP (Cell to Pack) structure in which a modularized battery case (battery pack) is assembled to the body. This makes it possible to suppress deformation of the battery cells in a vehicle with a CTP (Cell to Pack) structure.

[0038] A vehicle mounting structure according to a fifteenth aspect is a vehicle mounting structure for a battery stack according to any one of the first to thirteenth aspects, and includes a pair of skeletal parts that form the skeleton of the lower part of the vehicle, are arranged side by side in the first direction, and extend in the second direction, and the battery stack has an end on one side in the first direction and an end on the other side in the first direction that are fixed to the skeletal parts directly or via other members.

[0039] In a vehicle mounting structure according to a fifteenth aspect, a battery stack is fixed to a vehicle lower frame via two frame parts adjacent in a first direction. This vehicle mounting structure can be applied to, for example, a vehicle with a CTB (Cell to Body) structure in which the battery stack is modularized and assembled together with the body frame. This makes it possible to suppress deformation of the battery cells in a vehicle with a CTB (Cell to Body) structure. [Effects of the Invention]

[0040] As described above, the battery stack, the power storage device, and the vehicle mounting structure according to the present invention can suppress deformation of the battery cells when an external force is applied. [Brief explanation of the drawings]

[0041] [Figure 1] 1 is a plan view showing a schematic configuration of a lower part of a vehicle body of a vehicle equipped with a battery stack according to a first embodiment. [Figure 2] 2 is a cross-sectional view of the vehicle lower part taken along line 2-2 of FIG. 1. FIG. [Figure 3]1 is a partially exploded perspective view of a power storage device according to a first embodiment. [Figure 4] 1 is a partially exploded perspective view of a battery stack according to a first embodiment. FIG. [Figure 5] 5 is a cross-sectional view of the battery cell taken along line 5-5 in FIG. 4. FIG. [Figure 6] FIG. 1A is a plan view schematically showing a state before multiple battery cells and inter-cell members are constrained in the stacking direction in a battery stack manufacturing process, and FIG. 1B is a plan view partially enlarged showing the constrained state of multiple battery cells. [Figure 7] 1A is a plan view schematically showing a step of welding a bus bar to a battery cell in a battery stack manufacturing process, and FIG. 1B is a plan view showing a partially enlarged view of the welded portion. [Figure 8] 1A and 1B are schematic diagrams illustrating a first modified example of a battery stack, in which (A) is a partially enlarged plan view showing the state before the battery cells and inter-cell members are stacked in a first direction, and (B) is a partially enlarged plan view showing the state after the battery cells and inter-cell members have been stacked. [Figure 9] 10A and 10B are schematic views of a second modified example of a battery stack, in which (A) is a partially enlarged plan view showing the state before the battery cells and inter-cell members are stacked in a first direction, and (B) is a partially enlarged plan view showing the state after the battery cells and inter-cell members have been stacked. [Figure 10] 10A and 10B are schematic views of a third modified example of a battery stack, in which (A) is a partially enlarged plan view showing the state before the battery cells and inter-cell members are stacked in a first direction, and (B) is a partially enlarged plan view showing the state after the battery cells and inter-cell members have been stacked. [Figure 11] 10A and 10B are schematic views of a fourth modified example of a battery stack, in which (A) is a partially enlarged plan view showing the state before the battery cells and inter-cell members are stacked in a first direction, and (B) is a partially enlarged plan view showing the state after the battery cells and inter-cell members have been stacked. [Figure 12]FIG. 10 is an exploded perspective view showing a fifth modified example of the battery stack, in which the battery stack is partially disassembled. [Figure 13] 10 is a plan view of a vehicle equipped with a battery stack according to a second embodiment, showing a schematic configuration of the lower part of the vehicle body. FIG. [Figure 14] 14 is a cross-sectional view of the vehicle lower part taken along line 14-14 in FIG. 13. FIG. [Figure 15] 10 is a plan view schematically showing a battery stack according to a comparative example, illustrating a state in which a battery cell is buckled due to input of an external force. DETAILED DESCRIPTION OF THE INVENTION

[0042] First Embodiment A vehicle 10 according to the first embodiment will be described below with reference to Figures 1 to 7. Note that the arrow FR shown as appropriate in each figure indicates the front side of the vehicle, the arrow UP indicates the upper side of the vehicle, and the arrow LH indicates the left side of the vehicle. Furthermore, when the front-rear, up-down, and left-right directions are used in the following description unless otherwise specified, they refer to front-rear in the front-rear direction of the vehicle, up-down in the up-down direction of the vehicle, and left-right when facing the direction of travel.

[0043] In this embodiment, the first direction of the battery stack 40 indicated by the arrow W1 corresponds to the vehicle width direction, the second direction of the battery stack 40 indicated by the arrow W2 corresponds to the vehicle front-rear direction, and the third direction of the battery stack 40 indicated by the arrow W3 corresponds to the vehicle up-down direction.

[0044] Unless otherwise specified in the specification, each element is not limited to one and may be present in plural. Furthermore, in the drawings, substantially identical elements are denoted by the same reference numerals, and redundant explanations in the specification will be omitted.

[0045] 1 and 2, a vehicle 10 according to this embodiment is an electric vehicle that runs using the driving force of an electric motor (not shown), and includes a vehicle body 14. Examples of electric vehicles include a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), a battery electric vehicle (BEV), and a fuel cell electric vehicle (FCEV).

[0046] An electricity storage device 30 that supplies driving power to the electric motor is mounted on the lower part of the vehicle body 14. The electricity storage device 30 is configured by accommodating a plurality of battery stacks 40 inside a battery case 32. First, the configuration of the lower part of the vehicle body 14 will be described, followed by the configuration of the electricity storage device 30 and the configuration of the battery stacks 40, which are a main part of this embodiment.

[0047] (Vehicle underside configuration) The vehicle body 14 of the vehicle 10 includes a pair of left and right rockers 18L, 18R extending in the front-to-rear direction of the vehicle at the bottom of both sides in the vehicle width direction of the passenger compartment 16 (see FIG. 2), a front cross member 20 spanning the front ends of the left and right rockers 18L, 18R along the vehicle width direction, and a rear cross member 22 spanning the rear ends of the left and right rockers 18L, 18R along the vehicle width direction. The vehicle body 14 also includes a floor pan 26 (see FIG. 2) spanning the upper parts of the left and right rockers 18L, 18R and forming the floor surface of the passenger compartment 16.

[0048] In this embodiment, the left and right rockers 18L, 18R constitute the framework of the vehicle lower part, and are an example of a pair of framework parts arranged side by side in a first direction W1 (vehicle width direction) and extending in a second direction W2 (vehicle front-rear direction). Also, the front cross member 20 and the rear cross member 22 are an example of a pair of framework parts arranged side by side in the first direction W1 and extending in the second direction W2.

[0049] The left and right rockers 18L, 18R, the front cross member 20, and the rear cross member 22 are manufactured by extrusion molding of a light metal such as an aluminum alloy. The left and right rockers 18L, 18R are formed in an elongated shape with their longitudinal direction extending in the vehicle's fore-and-aft direction, and their cross sections as viewed from the vehicle's fore-and-aft direction are generally rectangular. In addition, the left and right rockers 18L, 18R are provided with support flanges 19 on their inner side surfaces in the vehicle width direction, protruding inward in the vehicle width direction. The front cross member 20 and the rear cross member 22 are formed in an elongated shape with their longitudinal direction extending in the vehicle width direction, and their cross sections viewed from the vehicle width direction are generally rectangular. Both longitudinal ends of the front cross member 20 are connected to the front ends of the left and right rockers 18L, 18R, and both longitudinal ends of the rear cross member 22 are connected to the rear ends of the left and right rockers 18L, 18R.

[0050] The floor pan 26 is manufactured by pressing a plate made of a light metal such as an aluminum alloy, and has a plate-like shape with its thickness extending in the vertical direction of the vehicle. The left and right edges of the floor pan 26 abut against the upper surfaces of the left and right rockers 18L, 18R from above the vehicle, and the front and rear edges of the floor pan 26 abut against the upper surfaces of the front cross member 20 and the rear cross member 22 from above the vehicle.

[0051] The above-described configuration of the lower part of the vehicle body 14 is one example and can be modified as appropriate. Furthermore, when the components of the lower part of the vehicle body 14 are made of the same type of light metal (e.g., aluminum alloy) as in this embodiment, the components can be joined by means of, for example, spot welding, friction stir welding, riveting, bolting, etc. Furthermore, when the components to be joined together are made of different types of materials (e.g., steel and aluminum alloy), the joining can be done by means of, for example, bolting, riveting, etc.

[0052] (Electricity storage device) In a plan view, the power storage device 30 is disposed between the front cross member 20 and the rear cross member 22. The power storage device 30 is mounted on the vehicle 10 with both sides in the vehicle width direction supported by a pair of left and right rockers 18L, 18R. In other words, the lower structure of the vehicle 10 has a CTP (Cell to Pack) structure in which a modularized battery case (battery pack) is assembled to the body.

[0053] Fig. 3 is an exploded perspective view of a part of the power storage device 30. As shown in Fig. 3, the power storage device 30 includes a flat box-shaped battery case 32 and a plurality of battery stacks 40 housed inside the battery case 32. The battery case 32 is configured by stacking a lower case 32L and an upper case 32U one above the other.

[0054] The lower case 32L, for example, has a shallow bathtub shape that opens toward the top of the vehicle and has flanges 33 on its edges in the vehicle width direction and the vehicle front-rear direction. The upper case 32U has a shallow bathtub shape that opens toward the bottom of the vehicle and has flanges 34 on its edges in the vehicle width direction and the vehicle front-rear direction. The upper case 32U is disposed below the floor pan 26 and overlaps the lower case 32L from above. The flanges 33, 34 of the lower case 32L and the upper case 32U are joined together with each other in a state where they are overlapped in the vertical direction. The flanges 33, 34 of the battery case 32 in the vehicle width direction abut from above against support flanges 19 provided on the left and right rockers 18R, 18L, and the abutting portions are joined together. The members can be joined by means of spot welding, friction stir welding, riveting, bolting, etc., and in this embodiment, bolting is used.

[0055] In addition, the flange portions 33, 34 of the battery case 32 on the front side of the vehicle may be connected to the front cross member 20, and the flange portions 33, 34 of the battery case 32 on the rear side of the vehicle may be connected to the rear cross member 22.

[0056] Furthermore, the upper case 32U is not essential to the above-described battery case 32. The upper case 32U may be omitted, and the floor pan 26 may also serve as the upper case.

[0057] The lower case 32L has vertical walls 36A, 36B, and 36C extending in the vehicle longitudinal direction and erected upward relative to a bottom plate 38 of the lower case 32L. The vertical walls 36A and 36B are disposed on one and the other side portions of the lower case 32L in the vehicle width direction, and the vertical wall 36C is disposed in a central portion of the lower case 32L in the vehicle width direction. The lower case 32L also has horizontal walls 37A and 37B extending in the vehicle width direction and erected upward relative to the bottom plate 38 of the lower case 32L as a framework extending in the vehicle width direction. The horizontal wall 37A, disposed at the front end of the lower case 32L, connects the front ends of the vertical walls 36A, 36B, and 36C in the vehicle width direction. The horizontal wall 37B, disposed at the rear end of the lower case 32L, connects the rear ends of the vertical walls 36A, 36B, and 36C in the vehicle width direction.

[0058] The lower case 32L and the upper case 32U are formed, for example, by press molding a metal plate. Each of the vertical wall portions 36A, 36B, and 36C of the lower case 32L is an example of at least two or more vertical wall portions arranged side by side in the first direction W1 (vehicle width direction) and extending in the second direction W2 (vehicle front-rear direction). Each of the horizontal wall portions 37A and 37B of the lower case 32L is an example of at least two or more horizontal wall portions arranged side by side in the second direction W2 and extending in the first direction W1.

[0059] (battery stack) The battery stack 40 will be described in detail below. Fig. 4 is an exploded perspective view of a partially disassembled battery stack. Fig. 5 is a cross-sectional view of a battery cell 50 taken along line 5-5 in Fig. 4.

[0060] In the following, when there is no need to distinguish between the vertical wall portion 36A, the vertical wall portion 36B, and the vertical wall portion 36C, they may be simply referred to as the vertical wall portion 36. In the following, the first direction W1 indicates the stacking direction of the battery cells 50, and the second direction W2 indicates a direction intersecting with the first direction W1. In this embodiment, the second direction W2 is a direction perpendicular to the first direction W1, but is not limited to this.

[0061] Inside the lower case 32L, a plurality of battery stacks 40 are housed between adjacent vertical wall portions 36 in the first direction W1 (vehicle width direction) and arranged side by side in the second direction W2 (vehicle front-rear direction) (see FIG. 3). One and the other ends of each battery stack 40 in the first direction W1 are fixed to the vertical wall portions 36 via brackets 46.

[0062] Each battery stack 40 includes a battery cell 50, an inter-cell member 60, an end plate portion 42, and a side plate portion 44.

[0063] (battery cell) A plurality of battery cells 50 are arranged side by side in the first direction W1. Each battery cell 50 is, for example, a lithium ion secondary battery, and has an exterior member 53 that houses an electrode body 52. ​​The exterior member 53 has a case portion 54 that houses the electrode body 52, and a pair of lid portions 56 that are provided on the end side of the case portion 54 in the second direction W2. In addition, in each battery cell 50, the rigidity of the pair of lid portions 56 is set to be higher than the rigidity of the case portion 54.

[0064] (electrode body) The electrode body 52 includes one or more laminates in which a positive electrode current collector 52A, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, a negative electrode current collector 52B, a negative electrode active material layer, an electrolyte layer, and a positive electrode active material layer are laminated in this order in a first direction W1.

[0065] The positive electrode current collector 52A and the negative electrode current collector 52B are sheet-shaped metal foils. The metals constituting the positive electrode current collector 52A and the negative electrode current collector 52B are not particularly limited, but examples thereof include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, and stainless steel. Al is preferred as the metal constituting the positive electrode current collector 52A. Cu is preferred as the material constituting the negative electrode current collector 52B. The positive electrode current collector 52A and the negative electrode current collector 52B may each have a collector tab. Each collector tab may be made of the same material as the corresponding current collector. The thickness of the positive electrode current collector 52A and the negative electrode current collector 52B may be, for example, 0.1 μm or more and 1 mm or less.

[0066] The positive electrode active material layer is a sheet-like layer containing a positive electrode active material. The positive electrode active material is not particularly limited, but preferably contains a lithium composite oxide. The positive electrode active material layer may also contain a conductive additive and a binder. Examples of the conductive additive include carbon materials, metal materials, and conductive polymer materials. Examples of the binder include vinyl halide resins, rubbers, and polyolefin resins. The thickness of the positive electrode active material layer may be, for example, 0.1 μm or more and 1 mm or less.

[0067] The negative electrode active material layer is a sheet-like layer containing a negative electrode active material. The negative electrode active material is not particularly limited, but examples include Li-based active materials such as metallic lithium, carbon-based active materials such as graphite, oxide-based active materials such as lithium titanate, and Si-based active materials such as elemental silicon. The negative electrode active material layer may also contain conductive additives and binders similar to those exemplified as the conductive additives and binders contained in the positive electrode active material layer. The thickness of the negative electrode active material layer may be, for example, 0.1 μm to 1 mm.

[0068] The electrolyte layer includes a solid electrolyte. That is, the battery cell 50 of this embodiment is a so-called solid-state battery. The solid electrolyte preferably includes one selected from the group consisting of a sulfide solid electrolyte, an oxide solid electrolyte, and a halide solid electrolyte. The solid electrolyte may also include an electrolytic solution in an amount of less than 10 mass% of the total amount of electrolyte. The solid electrolyte may also be a composite solid electrolyte including an inorganic solid electrolyte and a polymer electrolyte. The thickness of the electrolyte layer may be, for example, 0.1 μm or more and 1 mm or less.

[0069] (exterior materials) The exterior member 53 has a case portion 54 and a lid portion 56 provided in correspondence with an opening 54A of the case portion 54.

[0070] The case portion 54 is arranged to encase the plate-shaped electrode body 52. ​​As an example, the case portion 54 is formed in a cylindrical shape with the second direction W2 as its axial direction, and has openings 54A on one side and the other side in the second direction W2.

[0071] The case 54 can be made of a laminate film, a metal film, a thin metal plate, etc., and in this embodiment, it is made of a laminate film. A laminate film is a film-like multilayer body in which a resin layer (e.g., polypropylene, nylon, PET, etc.) is arranged on the surface of a metal layer. The thickness of the material of the case portion 54 may be, for example, 0.15 mm or more and 0.3 mm or less.

[0072] The lid portion 56 is provided to correspond to the opening 54A of the case portion 54. Therefore, the battery cell 50 of this embodiment has a pair of lid portions 56 that face each other in the second direction W2.

[0073] The cover portion 56 is conductive and constitutes a terminal member electrically connected to the electrode body 52. ​​The cover portion 56 has a conductive terminal portion 56A and a non-conductive resin portion 56B. The terminal portion 56A is a plate-shaped member whose thickness direction is in the second direction W2, and is inserted into the case portion 54 through the opening 54A. The terminal portion 56A has an inner surface disposed inside the case portion 54 that is electrically connected to current collectors (positive electrode current collector 52A, negative electrode current collector 52B). The terminal portion 56A has an outer surface disposed outside the case portion 54 that is electrically connected to a bus bar 58.

[0074] The terminal portion 56A and the current collector, or the terminal portion 56A and the bus bar 58, can be connected by means of laser welding, spot welding, riveting, bolting, or the like. In this embodiment, the components are connected by laser welding. The current collectors (positive electrode current collector 52A, negative electrode current collector 52B) may be connected to the terminal portion 56A via current collecting tabs, or may be connected to the terminal portion 56A without using current collecting tabs.

[0075] The material of terminal portion 56A is, for example, a metal, such as Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, etc. The metal constituting terminal portion 56A may be the same as or different from the metal constituting the current collectors (positive electrode current collector 52A, negative electrode current collector 52B), but is preferably the same.

[0076] On the other hand, the resin portion 56B of the cover portion 56 serves as an insulating member and is disposed between the case portion 54 and the terminal portion 56A. The case portion 54, the terminal portion 56A, and the resin portion 56B are integrally molded by, for example, injection molding. When the case portion 54 is formed of a laminate film, the terminal portion 56A and the resin portion 56B may be integrally molded and the case portion 54 and the resin portion 56B may be heat-sealed. When the case portion 54 is formed of a laminate film, the resin portion 56B may be omitted and the case portion 54 and the terminal portion 56A may be heat-sealed.

[0077] As described above, the battery cell 50 according to this embodiment is configured such that the exterior member 53 housing the electrode assembly 52 is connected to the case portion 54 made of laminate film and the metal plate-shaped lid portion 56. Therefore, as shown in Fig. 5, the portion of the case portion 54 that overlaps with the electrode assembly 52 in the first direction W1 forms a low-rigidity portion 53A of the exterior member 53, which has relatively low rigidity. On the other hand, the lid portion 56 forms a high-rigidity portion 53B that has higher rigidity than the low-rigidity portion 53A.

[0078] Here, "high rigidity" refers to a case where the strength of the material of the exterior member is relatively high, and for example, the Young's modulus of the high-rigidity portion may be higher than that of the low-rigidity portion, resulting in high rigidity. Also, "high rigidity" refers to a case where the second moment of area of ​​the material of the exterior member is relatively large, and for example, the thickness of the high-rigidity portion may be greater than the thickness of the low-rigidity portion, resulting in a relatively large second moment of area and high rigidity.

[0079] (Inter-cell components) The inter-cell member 60 is disposed between two adjacent battery cells 50 in the first direction W1, and has a first portion 61 and a second portion 62. The inter-cell member 60 constitutes a buffer member that absorbs expansion and contraction of the battery cells 50 during charging and discharging.

[0080] The first portion 61 contacts the cover portions 56 of two battery cells 50 arranged on one side and the other side of the first direction W1 with respect to the inter-cell member 60, and supports the two cover portions 56 adjacent in the first direction W1. The second portion 62 contacts the case portions 54 of two battery cells 50 arranged on one side and the other side of the first direction W1 with respect to the inter-cell member 60, and supports the two case portions 54 adjacent in the first direction W1.

[0081] The inter-cell member 60 includes the first portion 61, and is configured to come into contact with the lid body portion 56 (high-rigidity portion 53B) via the first portion 61, and to be able to restrain the lid body portion 56, which has higher rigidity than the case portion 54. This prevents the lid body portion 56 from shifting in position when an external force is applied to the stack of battery cells 50 and inter-cell members 60. When the lid body portion 56 is prevented from shifting in position in this way, stress concentration on the low-rigidity case portion 54 (low-rigidity portion 53A) is reduced when an external force is applied, and deformation of the battery cell 50 caused by buckling of the case portion 54 at the boundary with the lid body portion 56 is prevented.

[0082] Here, in order to effectively prevent misalignment of the cover body portion 56, in this embodiment, a predetermined surface treatment is applied to the inter-cell member 60 so that the frictional force between adjacent battery cells 50 in the first portion 61 and the second portion 62 is different.

[0083] More specifically, the friction force referred to here is the static friction force F [N], which is expressed by the following formula 1. In formula 1, μ represents the static friction coefficient, and N [N] represents the magnitude of the normal force. (Formula 1) F=μN[N]

[0084] A frictional force expressed by Equation 1 occurs at the contact portion between the inter-cell member 60 and the adjacent battery cell 50. The inter-cell member 60, together with the adjacent battery cell 50, is constrained in the first direction W1 by an end plate portion 42, which will be described later. Therefore, a normal force corresponding to the constraining pressure occurs on the opposing surface of the inter-cell member 60 that faces the battery cell 50 in the first direction W1.

[0085] In this embodiment, the thickness of the inter-cell member 60 in the second direction W2 is set to the same value in the first portion 61 and the second portion 62. Therefore, the first portion 61 and the second portion are constrained by approximately the same constraining pressure.

[0086] On the other hand, in this embodiment, the first portion 61 of the inter-cell member 60 has a roughened surface on the surface facing the battery cell 50. As a result, the coefficient of friction of the surface of the inter-cell member 60 is set to be greater in the first portion 61 than in the second portion 62 on this facing surface. This configures the friction force between the lid body portion 56 and the first portion 61 to be greater than the friction force between the case portion 54 and the second portion 62. As a result, in a stack of battery cells 50 and inter-cell members 60, misalignment of the lid body portion 56 is effectively suppressed.

[0087] The material of the inter-cell member 60 is not particularly limited, and can be appropriately selected from known materials such as resin, silicone, urethane, metal, etc. The inter-cell member 60 may be made of one of these materials or a combination of two or more materials. From the viewpoint of preventing short circuits between the battery cells 50, the inter-cell member 60 is preferably an insulator.

[0088] The material of the inter-cell member 60 is preferably an elastic body in terms of absorbing the dimensional tolerances of the battery cells 50 and the inter-cell member 60 and reducing changes in confining pressure caused by thermal expansion and contraction of the battery cells 50. In this case, one example of the elastic body is silicone.

[0089] Furthermore, the material of the inter-cell member 60 is preferably one that has excellent thermal insulation properties in terms of insulating between adjacent battery cells 50. Examples of insulating materials with excellent thermal insulation properties include urethane and foamed silicone, and foamed silicone is more preferable as it is an elastic body and has the performance of an insulating material. The inter-cell member 60 of this embodiment is formed from foamed silicone.

[0090] The inter-cell member 60 may also have a multi-layer structure made up of a combination of two or more types of members. For example, the inter-cell member may be formed with a two-layer structure made up of an insulating member layer and a heat insulating member layer.

[0091] The roughened surface treatment may be applied to both the first portion 61 of the inter-cell member 60 and the lid portion 56 of the battery cell 50, or only the lid portion 56. Furthermore, if the coefficient of friction of the surface of the inter-cell member 60 is sufficiently large due to the selection of the material, the second portion 62 may be subjected to a surface treatment to make it smooth.

[0092] (end plate) A pair of end plate portions 42 are arranged at one end in the first direction W1 and another end in the other direction W1 of the stacked body made up of stacked battery cells 50 and inter-cell components 60. The pair of end plate portions 42 restrain the stacked body from both sides in the first direction W1, and apply a predetermined restraining pressure along the first direction W1 to the stacked body.

[0093] The pair of end plate portions 42 are substantially rectangular plate bodies with the plate thickness direction aligned in the first direction W1, and are made of, for example, resin or metal.

[0094] (side plate) A pair of side plate portions 44 are arranged at one end and the other end in a second direction W2 perpendicular to the first direction W1 in a stack formed by stacking battery cells 50, inter-cell members 60, and a pair of end plate portions 42. The pair of side plate portions 44 are members that connect the pair of end plate portions 42 in the first direction W1, and stabilize the confining pressure applied to the battery cells 50 and inter-cell members 60.

[0095] The pair of side plates 44 are formed of plates that are long in the first direction W1 and are made of resin or metal. When viewed from the first direction W1, each side plate 44 has a generally U-shape that opens toward the stack body. As a result, both side surfaces of the stack body in the second direction W2 and parts of the top and bottom surfaces are covered from the outside by the pair of side plates 44.

[0096] The pair of side plate portions 44 are fixed to the pair of end plate portions 42 using bolts 48. The bolts 48 are inserted into bolt insertion holes (reference numerals omitted) provided at one and the other ends of the pair of end plate portions 42 in the first direction W1, and are screwed into female threaded holes (reference numerals omitted) formed in the side surfaces of the pair of end plate portions 42. In this way, the pair of end plate portions 42 are connected in the first direction W1 by the pair of side plate portions 44.

[0097] Furthermore, the pair of side plate portions 44 are fixed to the battery case 32 via a plurality of brackets 46 as other members. As an example, each bracket 46 is configured as an L-shaped bracket having a first main surface 46A facing the first direction W1 and a second main surface 46B facing the second direction W1. The first main surface 46A is fastened together with the side plate portion 44 to the end of the battery stack 40 in the first direction W1 using bolts 48. The second main surface 46B is fixed to the vertical wall portion 36 of the lower case 32L by a method such as bolting or welding. In this way, the battery stack 40 is fixed to the vertical wall portion 36 of the lower case 32L via the brackets 46 at one end in the first direction W1 and the other end in the first direction W1.

[0098] In addition, a bracket may be integrally formed with at least one of the end plate portion 42 and the side plate portion 44, in which case the end portion on one side of the first direction W1 of the battery stack 40 and the end portion on the other side of the first direction W1 are directly fixed to the vertical wall portion 36 of the lower case 32L.

[0099] The battery stack 40 is formed as a long rectangular parallelepiped as a whole, with its longitudinal axis extending in the first direction W1 (vehicle width direction). In the battery stack 40, the positive electrode side cover body portion 56 or the negative electrode side cover body portion 56 of adjacent battery cells 50 are connected to each other via a bus bar 58 (see FIG. 4 ) that is a conductive member. Note that the configuration of the battery stack 40 is not limited to the above and can be modified as appropriate. For example, at least one of the end plate portion 42 and the side plate portion 44 may be omitted.

[0100] (Battery stack manufacturing method) The battery stack 40 is manufactured, for example, by the following first to fourth steps.

[0101] (1st step) The first step is a step of stacking the battery cells 50 and the inter-cell components 60 alternately in the first direction W1 to obtain a stack (not shown).

[0102] (2nd process) The second step is a step of restraining the stack of battery cells 50 and inter-cell members 60 in the first direction W1 with a pair of end plate portions 42 (see FIG. 6(A)). In this step, an external force (restraining force) in the first direction W1 is applied to each battery cell 50, but the support of the first portion 61 of the inter-cell member 60 prevents the lid body portion 56 of the battery cell 50 from shifting in the first direction W1 (see FIG. 6(B)).

[0103] (3rd step) The third step is a step of welding a bus bar 58 to the side surface of the stack facing the second direction W2 (see FIG. 7(A)). In this step, the positive electrode side cover body portion 56 or the negative electrode side cover body portion 56 of the battery cells 50 adjacent in the first direction W1 are electrically connected via the bus bar 58. At this time, in order to reduce the gap between the bus bar 58 and the cover body portion 56, the bus bar 58 is pressed against the cover body portion 56 side during welding. Therefore, in this step, an external force (restraining force) in the second direction W2 is applied to each battery cell 50, but the support of the first portion 61 of the inter-cell member 60 prevents the cover body portion 56 of the battery cell 50 from shifting in the second direction W2 (see FIG. 7(B)).

[0104] (4th step) The fourth step is a step (not shown) of fixing a pair of side plates 44 to a stack of battery cells 50, inter-cell members 60, and a pair of end plates 42. In this step, the pair of end plates 42 are connected in the first direction W1 by the pair of side plates 44. In this state, the bus bars 58 arranged facing the second direction W2 are covered by the side plates 44. As a result, the live parts of the battery cells 50 are protected by the side plates 44.

[0105] The side plate portion 44 may be configured to have a groove or an opening that exposes the welded portion of the bus bar 58. In this case, the bus bar 58 can be welded through the groove or the opening after the side plate portion 44 is installed, and therefore the third step may be performed after the fourth step.

[0106] (Action and effect) Next, the operation and effects of the first embodiment will be described.

[0107] The battery stack 40 according to the first embodiment includes a plurality of battery cells 50 arranged side by side in a first direction W1, and at least one inter-cell member 60 arranged between adjacent battery cells 50. Each battery cell 50 has an electrode body 52 housed in an exterior member 53. The exterior member 53 includes a low-rigidity portion 53A (case portion 54) that overlaps with the electrode body 52 in the first direction W1, and a high-rigidity portion 53B (lid portion 56) that has higher rigidity than the low-rigidity portion 53A and is provided on the end side of the low-rigidity portion 53A in a second direction W2 that intersects with the first direction W1.

[0108] Here, the expansion and contraction of battery cells during charging and discharging is caused by the expansion and contraction of the electrode assembly housed in the battery cell. For this reason, inter-cell members arranged between battery cells are generally arranged in low-rigidity portions of the exterior member that are subject to large amounts of displacement due to the expansion and contraction of the electrode assembly, and are not usually arranged in positions near the end of the exterior member (high-rigidity portions). That is, as in the battery stack 300 according to the comparative example shown in FIG. 15 , the inter-cell members 320 arranged between battery cells 310 are arranged only in positions that contact the case portion 312 (low-rigidity portions) of the exterior member 311 of the battery cell 310, and are not arranged in positions that contact the lid portion 314 (high-rigidity portions) of the battery cell 310. Therefore, the end side of the exterior member 311 is not constrained by contact with the inter-cell members 320. Therefore, when an external force is applied, stress concentrates on the case portion 312 at the boundary with the lid portion 314, which is not constrained by the inter-cell members 320, and there is a risk of the battery cell 310 being deformed.

[0109] In contrast, the inter-cell member 60 according to this embodiment has a first portion 61 that contacts the high-rigidity portion 53B of the exterior member 53 and a second portion 62 that contacts the low-rigidity portion 53A. Therefore, the high-rigidity portion of the exterior member 53 that is provided on the end side in the second direction W2 comes into contact with and is restrained by the inter-cell member 60. This suppresses displacement of the high-rigidity portion 53B even when an external force is applied, and reduces stress concentration on the case portion 54 at the boundary between the case portion 54 and the lid portion 56 of the exterior member 53, thereby suppressing deformation of the battery cell 50.

[0110] That is, as in this embodiment, even when the case portion 54 of the exterior member 53 is made of a low-rigidity laminate film, deformation of the battery cell 50 can be suppressed. Furthermore, by making the case portion 54 out of a laminate film, it is easy to ensure insulation from the terminal portion 56A of the lid body portion 56 connected to the electrode body 52, and as a result, it is possible to increase the cross-sectional area of ​​the terminal portion 56A, thereby improving the heat dissipation of the battery cell 50. This configuration effectively suppresses temperature increases in the battery cell 50 due to charging and discharging.

[0111] Furthermore, in this embodiment, the coefficient of friction of the inter-cell member 60 is set to be greater in the first portion 61 than in the second portion 62. As a result, the frictional force generated at the contact portion between the cover body portion 56 of the exterior member 53 and the first portion 61 of the inter-cell member 60 is greater than the frictional force generated at the contact portion between the case portion 54 and the second portion 62. As a result, the restraining force of the inter-cell member 60 on the cover body portion 56 is increased relative to the restraining force on the case portion 54, and deformation of the battery cells 50 is effectively suppressed.

[0112] Furthermore, in this embodiment, the inter-cell members 60 are made of a heat insulating member, so that the heat insulation between the battery cells 50 can be achieved by the inter-cell members 60. This makes it possible to prevent a heat chain reaction to other adjacent battery cells 50 when a battery cell 50 generates abnormal heat.

[0113] Furthermore, in this embodiment, each battery cell 50 has a pair of lid body portions 56 that face each other in a second direction W2 that is perpendicular to the first direction W1. This effectively prevents the lid body portions 56 from shifting in position in the second direction W2 due to an external force applied to the battery stack 40 from the second direction W2. This prevents the battery cell 50 from being deformed by an external force applied when the bus bar 58 is pressed against the battery cell 50, for example, in the manufacturing process of welding the bus bar 58 to the battery cell 50.

[0114] In this embodiment, the pair of high-rigidity portions 53B (lid portions 56) provided on the exterior member 53 are configured to be conductive. This allows the high-rigidity portions 53B to be used as terminal members, and the high-rigidity portions 53B of the exterior member 53 and the terminal members to be configured as a single part, thereby reducing the number of parts.

[0115] Furthermore, in this embodiment, a pair of end plate portions 42 is provided, one at an end on one side in the first direction W1 of the battery stack 40 and the other at an end on the other side in the first direction W1. This allows a predetermined constraining pressure to be applied in the first direction W1 to the stack of battery cells 50 and inter-cell members 60, stabilizing the constraining of the battery cells 50 by the inter-cell members 60 and effectively suppressing deformation of the battery cells 50.

[0116] Furthermore, in this embodiment, the pair of end plate portions 42 are connected in the first direction W1 by the side plate portions 44, so that the restraint pressure applied from the pair of end plate portions 42 is more stable, and deformation of the battery cells 50 can be effectively suppressed.

[0117] Furthermore, the electrode body 52 of the battery cell 50 of this embodiment is configured to include a solid electrolyte, and the battery cell 50 is configured as a so-called solid-state battery. Therefore, the confining pressure applied to the stack of the battery cells 50 and the inter-cell members 60 can be made higher than that of battery cells of liquid-state batteries. Therefore, the confining force on the battery cells 50 in the first direction W1 can be made higher than that of a battery stack using battery cells of liquid-state batteries, and deformation of the battery cells 50 can be effectively suppressed.

[0118] Furthermore, in the energy storage device 30 including the above-described battery stack 40, the battery stack 40 is fixed inside the lower case 32L (battery case 32) via two vertical wall portions 36 adjacent in the first direction W1. In this way, the energy storage device 30 can be applied to a vehicle with a CTP (Cell to Pack) structure, and therefore, in a vehicle 10 with a CTP (Cell to Pack) structure, deformation of the battery cells 50 due to external forces such as vibrations transmitted from the vehicle body 14 via the battery case 32 during traveling can be suppressed.

[0119] Hereinafter, several modified examples that can be applied to the above embodiment will be described. Note that the same components as those in the first embodiment will be given the same reference numerals and the description thereof will be omitted.

[0120] (First Modification) A battery stack 70 according to a first modification will be described below with reference to Figures 8(A) and 8(B). Figure 8(A) is a partially enlarged plan view showing the battery cells 50 and the inter-cell members 72 before they are stacked in the first direction W1, and Figure 8(B) is a partially enlarged plan view showing the battery cells 50 and the inter-cell members 72 after they have been stacked.

[0121] 8(A), the inter-cell member 72 has a first portion 73 that contacts the lid portion 56 (high-rigidity portion 53B) and a second portion 74 that contacts the case portion 54 (low-rigidity portion 53A) between adjacent battery cells 50. Here, in this first modified example, the first portion 73 of the inter-cell member 72 is provided with protrusions 73A that protrude on both sides in the first direction W1 relative to the second portion 74 that contacts the case portion 54 of the battery cell 50. Therefore, the thickness of the inter-cell member 72 in the first direction W1 is configured so that the thickness T1 of the first portion 73 is thicker than the thickness T2 of the second portion 74. The other configurations are the same as those of the first embodiment.

[0122] According to the above configuration, when the battery cells 50 and the inter-cell members 72 are stacked while being restrained in the first direction W1, the cover body portion 56 (high-rigidity portion 53B) of the battery cell 50 contacts the inter-cell member 72 preferentially over the case portion 54 (low-rigidity portion 53A). Therefore, the normal force N1 acting on the contact surface with the first portion 73 is increased relative to the normal force N2 acting on the contact surface with the second portion 74. This allows the configuration to make the frictional force acting on the contact portion between the cover body portion 56 of the exterior member 53 and the first portion 73 of the inter-cell member 72 greater than the frictional force acting on the contact portion between the case portion 54 and the second portion 74. Therefore, the battery stack 70 according to the first modification can achieve the same functions and effects as the battery stack 40 according to the first embodiment.

[0123] Furthermore, in this embodiment, because the inter-cell component 72 is made of an elastic material, the protruding portion 73A of the first portion 73 is elastically deformed and crushed by the confining pressure during stacking, as shown in Figure 8(B). This makes it possible to accommodate the dimensional tolerances of the battery cells 50 and the inter-cell component 72. It also makes it possible to reduce changes in confining pressure caused by factors such as thermal expansion and contraction of the battery cells 50. However, in the first modified example, it is not essential that the inter-cell component 72 be made of an elastic material.

[0124] (Second Modification) A battery stack 80 according to a second modified example will be described below with reference to Figures 9(A) and 9(B). Figure 9(A) is a partially enlarged plan view showing the battery cells 50 and the inter-cell members 82 before they are stacked in the first direction W1, and Figure 9(B) is a partially enlarged plan view showing the battery cells 50 and the inter-cell members 82 after they have been stacked.

[0125] 9(A), the inter-cell member 82 has a first portion 83 that contacts the lid portion 56 (high rigidity portion 53B) and a second portion 84 that contacts the case portion 54 (low rigidity portion 53A) between adjacent battery cells 50. Here, in the second modified example, the Young's modulus of the inter-cell member 82 is set to be greater in the first portion 83 than in the second portion 84. The other configurations are the same as those in the first embodiment.

[0126] In the inter-cell member 82, for example, the first portion 83 and the second portion 84 may be formed from different materials, thereby making the Young's modulus of the first portion 83 different from the Young's modulus of the second portion 84. Alternatively, for example, the first portion 83 and the second portion 84 may be formed from the same material, with the first portion 83 being non-porous and the second portion 84 being porous, thereby making the Young's modulus of the first portion 83 different from the Young's modulus of the second portion 84.

[0127] According to the above configuration, when the battery cells 50 and the inter-cell members 82 are restrained and stacked, as shown in Fig. 9(B), the normal force N1 acting on the contact surface with the first portion 83 is relatively greater than the normal force N2 acting on the contact surface with the second portion. This makes it possible to configure the frictional force acting on the contact portion between the lid portion 56 of the battery cell 50 and the first portion 83 of the inter-cell member 82 to be greater than the frictional force acting on the contact portion between the case portion 54 and the second portion 84. Therefore, the battery stack 70 according to the first modification can achieve the same functions and effects as the battery stack 40 according to the first embodiment.

[0128] (Third Modification) A battery stack 90 according to a third modification will be described below with reference to Figures 10(A) and 10(B). Figure 10(A) is a partially enlarged plan view showing the battery cells 50 and the inter-cell members 92 before they are stacked in the first direction W1, and Figure 10(B) is a partially enlarged plan view showing the battery cells 50 and the inter-cell members 92 after they have been stacked.

[0129] 10(A), the inter-cell member 92 has a first portion 93 that contacts the lid body portion 56 (high rigidity portion 53B) between adjacent battery cells 50, and a second portion 94 that contacts the case portion 54 (low rigidity portion 53A). Here, in the third modified example, a recessed portion 96 is provided in the first portion 93 of the inter-cell member 92, and a protruding portion 98 provided on the lid body portion 56 of the battery cell 50 is configured to fit into the recessed portion 96. In this way, the first portion 93 of the inter-cell member 92 fits into the lid body portion 56 of the battery cell 50.

[0130] The recesses 96 are provided on both surfaces of the first portion 93 in the first direction W1 and are constituted by holes or grooves recessed in the first direction W1. The protrusions 98 are provided on both surfaces of the cover body 56 in the first direction W1 and are constituted by columnar or linear protrusions protruding in the first direction W1.

[0131] According to the above configuration, the first portion 93 of the inter-cell member 92, which contacts the lid body portion 56 (high-rigidity portion 53B), is fitted with the lid body portion 56. This relatively increases the support force of the inter-cell member 92 for the lid body portion 56, effectively suppressing deformation of the battery cells 50.

[0132] In the above configuration, the recessed portion 96 is provided in the first portion 93 of the inter-cell member 92, and the protruding portion 98 is provided in the lid portion 56 of the battery cell 50, but these may be reversed. That is, the protruding portion 98 may be provided in the first portion 93 of the inter-cell member 92, and the recessed portion 96 may be provided in the lid portion 56 of the battery cell 50.

[0133] (Fourth Modification) A battery stack 110 according to a fourth modification will be described below with reference to Figures 11(A) and 11(B). Figure 11(A) is a partially enlarged plan view showing the battery cells 50 and the inter-cell members 112 before they are stacked in the first direction W1, and Figure 11(B) is a partially enlarged plan view showing the battery cells 50 and the inter-cell members 112 after they have been stacked.

[0134] In this fourth variant, unlike the first to third variants, the inter-cell member 112 is configured so that the frictional force between the case portion 54 (low rigidity portion 53A) of the battery cell 50 and the second portion 114 is greater than the frictional force between the lid portion 56 (high rigidity portion 53B) and the first portion 113.

[0135] 11(A), the inter-cell member 112 has a first portion 113 that contacts the lid portion 56 and a second portion 114 that contacts the case portion 54 between adjacent battery cells 50. As an example, in this fourth modified example, the second portion 114 of the inter-cell member 112 is provided with protrusions 114A that protrude on both sides in the first direction W1 relative to the first portion 113 that contacts the lid portion 56 of the battery cell 50. Therefore, the thickness of the inter-cell member 112 in the first direction W1 is configured so that the thickness T2 of the second portion 114 is thicker than the thickness T1 of the first portion 113. The other configurations are the same as those of the first embodiment.

[0136] According to the configuration of the fourth modified example, the highly rigid lid body portion 56 is restrained by the first portion 113 of the inter-cell component 112. Therefore, similar to the above embodiment, deformation of the battery cells 50 can be suppressed.

[0137] On the other hand, when the battery cells 50 and the inter-cell members 112 are stacked while being restrained in the first direction W1, the case portion 54 (low-rigidity portion 53A) of the exterior member 53 comes into contact with the inter-cell member 112 preferentially over the cover body portion 56 (high-rigidity portion 53B). Therefore, the normal force N2 acting on the contact surface with the first portion 113 is relatively increased relative to the normal force N1 acting on the contact surface with the first portion 113. As a result, the frictional force acting on the contact portion between the case portion 54 of the battery cell 50 and the second portion 114 of the inter-cell member 112 is greater than the frictional force acting on the contact portion between the cover body portion 56 and the second portion 114. In this state, the restraining pressure acting on the case portion 54 of the battery cell 50 can be relatively increased, so that the electrode body 52 housed in the case portion 54 can be restrained with sufficient restraining pressure while suppressing misalignment of the cover body portion 56.

[0138] Furthermore, in this embodiment, because the inter-cell component 112 is made of an elastic material, the protruding portion 114A of the second portion 114 is elastically deformed and crushed by the constraining pressure during stacking, as shown in FIG. 11(B). This makes it possible to accommodate the dimensional tolerances of the battery cells 50 and the inter-cell component 112. It also makes it possible to reduce changes in constraining pressure caused by factors such as thermal expansion and contraction of the battery cells 50. However, in the fourth modified example, it is not essential that the inter-cell component 112 be made of an elastic material.

[0139] (Fifth Modification) A battery stack 120 according to a fifth modified example will be described below with reference to Fig. 12. Fig. 12 is an exploded perspective view of the battery stack 120, in which the battery stack 120 is partially disassembled.

[0140] In the battery stack 40 according to the first embodiment, the side plates 44 are arranged in pairs on one side and the other side in the second direction perpendicular to the first direction W1, but it is sufficient that the side plates 44 are arranged on at least one side in the direction perpendicular to the first direction W1. Therefore, in the first embodiment, the side plates 44 may be arranged on only one side in the second direction.

[0141] 12 , the side plate portions 44 may be arranged in a third direction W3 that is perpendicular to the first direction W1 and the second direction W2. That is, in the battery stack 120, a pair of side plate portions 44 are arranged on one side and the other side of the third direction W3 so as to cover the top and bottom surfaces of a stack of battery cells 50, inter-cell members 60, and a pair of end plate portions 42. In this case, too, one of the pair of side plate portions 44 may be omitted.

[0142] Second Embodiment A vehicle 100 equipped with a battery stack 40 according to the second embodiment will be described below with reference to Figures 13 and 14. Note that the same components as those in the first embodiment described above are given the same reference numerals and descriptions thereof will be omitted.

[0143] The vehicle 100 is an electric vehicle that runs using the driving force of an electric motor (not shown), and includes a vehicle body 102. A plurality of battery stacks 40 that supply driving power to the electric motor are mounted on the lower part of the vehicle 100. The plurality of battery stacks 40 are fixed via brackets 46 to left and right rockers 18L, 18R that form the vehicle's framework, and to the center tunnel 24. In other words, the vehicle 100 has a CTB (Cell to Body) structure in which the battery stacks are modularized and assembled together with the body framework.

[0144] Specifically, the vehicle body 102 includes a pair of left and right rockers 18L, 18R extending in the fore-and-aft direction of the vehicle at the bottom of both sides in the vehicle width direction of the passenger compartment (not shown), a front cross member 20 spanning the front ends of the left and right rockers 18L, 18R along the vehicle width direction, and a rear cross member 22 spanning the rear ends of the left and right rockers 18L, 18R along the vehicle width direction. The vehicle body 102 also includes a center tunnel 24 spanning the front and rear direction of the vehicle at the center in the vehicle width direction between the left and right rockers 18L, 18R and spanning between the front cross member 20 and the rear cross member 22.

[0145] The pair of left and right rockers 18L, 18R and the center tunnel 24 correspond to "a pair of framework parts arranged side by side in a first direction and extending in a second direction perpendicular to the first direction."

[0146] The vehicle body 102 also includes a floor pan 26 that spans the upper portions of the left and right rockers 18L, 18R to form the floor surface of the vehicle compartment, and a bottom plate 28 that spans the lower portions (between the lower ends) of the left and right rockers 18L, 18R to form the underside of the vehicle body 102.

[0147] The bottom plate 28, like the floor pan 26, is manufactured by press-forming a plate made of a light metal such as an aluminum alloy, and has a plate-like shape with its thickness extending in the vertical direction of the vehicle.

[0148] (Vehicle mounting structure) In the vehicle 100, a plurality of battery stacks 40 are mounted (disposed) side by side in the fore-and-aft direction of the vehicle between the left locker 18L and the center tunnel 24, and between the right locker 18R and the center tunnel 24. The upper sides of the plurality of battery stacks 40 are covered by a floor pan 26, and the lower sides of the plurality of battery stacks 40 are covered by a bottom plate 28. In the following description, the left locker 18L and the right locker 18R may be simply referred to as lockers 18.

[0149] Each battery stack 40 is housed between the rocker 18 and the center tunnel 24, and is fixed to the rocker 18 and the center tunnel 24 via a bracket 46, which serves as an additional member.

[0150] Specifically, a first main surface 46A of a bracket 46 is fixed to both ends of each battery stack 40 in the direction in which the rockers 18 and the center tunnel 24 are aligned (i.e., both ends of each battery stack 40 in the first direction W1). In this embodiment, the first main surface 46A of the bracket is fixed to both ends of a pair of side plate portions 44 in the first direction W1. In addition, a second main surface 46B of the bracket 46 is fixed to the opposing side surfaces of the rocker 18 and center tunnel 24. This second main surface 46B is disposed between the side surfaces of the rocker 18 and center tunnel 24 and the pair of end plate portions 42 of the battery stack 40.

[0151] The pair of end plate portions 42 of each battery stack 40 may abut against the rocker 18 and the center tunnel 24, but it is preferable that they do not abut against them. When they do not abut against them, each battery stack 40 is restrained by the vehicle body 102 without abutting against the rocker 18 and the center tunnel 24. This reduces the impact transmitted to each battery stack 40 via the rocker 18 when an external force is input to the lower part of the vehicle body 102 from the vehicle width direction (i.e., the second direction W2 of each battery stack 40). Furthermore, it is possible to suppress the vibration of the vehicle body 102 from being transmitted to each battery stack 40 while the vehicle is traveling.

[0152] In the vehicle mounting structure described above, each battery stack 40 is fixed to the vehicle 100 via the framework of the vehicle's lower part, two framework parts (rocker 18 and center tunnel 24) adjacent in the first direction W1, and brackets 46. In this way, the vehicle mounting structure according to this embodiment can be applied to a vehicle with a CTB (Cell to Body) structure in which the battery stack is modularized and assembled together with the framework of the body. This makes it possible to suppress deformation of the battery cells 50 in a CTB (Cell to Body) vehicle 100.

[0153] In the above-described vehicle mounting structure, the center tunnel 24 may be omitted. In this case, each battery stack 40 may be housed between the left and right lockers 18 and fixed to the lockers 18 via brackets 46 as additional members.

[0154] Furthermore, in the above-described vehicle mounting structure, it is not essential that each battery stack 40 be fixed to the vehicle body 102 via the bracket 46. The bracket 46 may be omitted. In the case where the bracket 46 is omitted, the bracket may be integrally formed with the pair of end plate portions 42 or the pair of side plate portions 44.

[0155] In addition, in the above-described embodiments and modifications, the battery cell 50 is a solid-state battery, but the present invention is not limited to this. The battery cell may be a liquid-based battery. In this case, the electrolyte layer of the electrode assembly is composed of an electrolytic solution and a separator.

[0156] It goes without saying that the configurations of the above-described modified examples can be applied to the vehicle 100 of the second embodiment. Furthermore, the configurations of the above-described embodiments and modified examples can be combined or substituted without departing from the spirit of the invention. [Explanation of symbols]

[0157] 10,100 vehicles 18L, 18R Rocker (framework) 24 Center tunnel (framework) 30 Electricity storage device 32 Battery case 36A,36B,36C Vertical wall part 40,70,80,90,110,120 battery stack 42 End plate part 44 Side plate part 50 battery cells 52 Electrode body 53 Exterior materials 53A Low rigidity part 53B High rigidity part 54 Case part 56 Lid body 60,72,82,92,112 Inter-cell members 61 73,83,93,113 Part 1 62,74,84,94,114 2nd part

Claims

1. a plurality of battery cells arranged side by side in a first direction, each battery cell having an electrode body housed in an exterior member; At least one inter-cell member disposed between adjacent battery cells, The exterior member is a low-rigidity portion overlapping the electrode body in a first direction; a high-rigidity portion having a higher rigidity than the low-rigidity portion and provided on an end side of the low-rigidity portion in a second direction intersecting with the first direction, the inter-cell member has a first portion in contact with the high-rigidity portion and a second portion in contact with the low-rigidity portion; Battery stack.

2. The low rigidity portion is made of a laminate film. The battery stack according to claim 1 .

3. a friction force between the high-rigidity portion and the first portion is greater than a friction force between the low-rigidity portion and the second portion; The battery stack according to claim 1 or 2.

4. With respect to the coefficient of friction of the inter-cell member, the coefficient of friction of the first portion is greater than the coefficient of friction of the second portion. The battery stack according to claim 3 .

5. With respect to the thickness of the inter-cell member in the first direction, the thickness of the first portion is greater than the thickness of the second portion. The battery stack according to claim 3 .

6. With respect to the Young's modulus of the inter-cell member, the Young's modulus of the first portion is greater than the Young's modulus of the second portion. The battery stack according to claim 3 .

7. the inter-cell member has the first portion fitted to the high-rigidity portion; The battery stack according to claim 1 or 2.

8. The inter-cell member is a heat insulating member. The battery stack according to claim 1 or 2.

9. the battery cell has a pair of the high-rigidity portions facing each other in a second direction that intersects with the first direction; The battery stack according to claim 1 or 2.

10. The pair of high-rigidity portions are electrically conductive. The battery stack according to claim 9 .

11. a pair of end plate portions disposed at an end on one side in the first direction and an end on the other side in the first direction; The battery stack according to claim 1 or 2.

12. The device further includes a side plate portion disposed at at least one end in a direction perpendicular to the first direction, the side plate portion connecting the pair of end plate portions in the first direction. The battery stack according to claim 11 .

13. The electrode body includes a solid electrolyte. The battery stack according to claim 1 or 2.

14. A power storage device comprising the battery stack according to claim 1, a battery case including at least two vertical wall portions arranged side by side in the first direction and extending in the second direction, the battery case accommodating the battery stack between adjacent vertical wall portions; the battery stack is fixed at one end on the first direction side and the other end on the first direction side to the vertical wall portion directly or via another member; Energy storage device.

15. The battery stack mounting structure for a vehicle according to claim 1, a pair of skeletal parts that form a skeleton of a lower part of the vehicle, are arranged side by side in the first direction, and extend in the second direction; an end portion of the battery stack on one side in the first direction and an end portion of the battery stack on the other side in the first direction are fixed to the skeleton portion directly or via another member; Vehicle mounting structure.

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