Power storage device

Abstract

A power storage device (1) comprises: an exterior case (2); a battery cell assembly (3) that is accommodated in the exterior case (2) and comprises a plurality of battery cells (21); and a flow path defining member (5) that is attached to an outer surface (13a) of the exterior case (2) and defines, together with the outer surface (13a) of the exterior case (2), an air flow path (6) which has an air supply port (6a) and an exhaust port (6b) and which is configured such that cooling air flows from the air supply port (6a) to the exhaust port (6b).

Description

Power storage device

[0001] The present disclosure relates to a power storage device.

[0002] The power storage device disclosed in Patent Document 1 includes an exterior case, a battery cell assembly (including a plurality of battery cells) housed inside the exterior case, and an air flow path for air-cooling the battery cell assembly. The air flow path is provided inside the exterior case. The exterior case is provided with an air inlet and an air outlet for intake and exhaust of air to and from the air flow path.

[0003] Japanese Patent Application Laid-Open No. 2020-42982

[0004] In the power storage device disclosed in Patent Document 1, the air flow path provided inside the exterior case contributes to the cooling efficiency of the battery cells. However, in this power storage device, an external force applied during pre-installation (e.g., during transportation) directly acts on the exterior case. Although the air flow path functions as a crush zone that absorbs the external force to some extent by deformation, the structure in which the external force directly acts on the exterior case has room for improvement in terms of protecting the battery cells. Also, in this power storage device, since an air flow path is provided inside the exterior case, it is necessary to provide filters at the air inlet and the air outlet in order to prevent foreign matter from entering the interior of the exterior case, which complicates the structure.

[0005] An object of the present disclosure is to achieve protection of battery cells against external forces and simplification of the structure while ensuring the cooling efficiency of the battery cells in a power storage device.

[0006] One aspect of the present disclosure provides a power storage device including an exterior case, a battery cell assembly housed inside the exterior case and including a plurality of battery cells, and a flow path defining member that is attached to the outer surface of the exterior case and defines, together with the outer surface of the exterior case, an air flow path having an air inlet and an air outlet and configured such that cooling air flows from the air inlet to the air outlet.

[0007] According to the power storage device of the present disclosure, it is possible to achieve protection of battery cells against external forces and simplification of the structure while ensuring the cooling efficiency of the battery cells.

[0008] A perspective view of the energy storage device according to an embodiment of this disclosure, seen from the bottom. A perspective view of the energy storage device according to an embodiment of this disclosure, seen from the top. An exploded perspective view of the energy storage device according to an embodiment of this disclosure, seen from the bottom. An exploded perspective view of the energy storage device according to an embodiment of this disclosure, seen from the top. A cross-sectional view along line V-V in Figure 1. An enlarged view of part VI in Figure 1. An enlarged view of part VII in Figure 1. An enlarged view of part VIII in Figure 1. An exploded perspective view of the battery cell assembly. A perspective view of the flow path definition plate seen from the outside. A perspective view of the flow path definition plate seen from the inside. A cross-sectional view similar to Figure 5 showing an energy storage device according to a first modification of an embodiment of this disclosure. A perspective view of the flow path definition plate seen from the outside according to a second modification of an embodiment of this disclosure. A cross-sectional view similar to Figure 7 showing an energy storage device according to a third embodiment of an embodiment of this disclosure. A perspective view of the flow path definition cylinder according to a fourth embodiment of an embodiment of this disclosure, seen from the outside. A perspective view of the flow path definition cylinder according to a fourth embodiment of an embodiment of this disclosure, seen from the inside.

[0009] An energy storage device according to one embodiment of the present disclosure comprises an outer case, a battery cell assembly housed within the outer case and comprising a plurality of battery cells, and a flow path defining member attached to the outer surface of the outer case, which defines an air flow path together with the outer surface of the outer case, having an air intake port and an exhaust port, and configured such that cooling air flows from the air intake port to the exhaust port.

[0010] The airflow path is defined by the flow path defining member and the outer surface of the outer casing. In other words, the outer surface of the outer casing is in direct contact with the airflow path. Therefore, the cooling efficiency of the battery cells in the battery cell assembly housed within the outer casing can be ensured by air cooling.

[0011] The airflow channel functions as a crash zone that absorbs external forces to some extent through the deformation of the channel defining member. Therefore, external forces applied before installation (e.g., during transportation) do not directly act on the outer casing, effectively protecting the battery cells of the battery cell assembly housed within the outer casing from external forces.

[0012] Since the air passage is located on the outside of the outer casing, foreign matter cannot enter the outer casing through the air passage. Therefore, there is no need to install filters at the air intake and exhaust ports of the air passage to prevent foreign matter from entering, which simplifies the structure.

[0013] Each of the plurality of battery cells is cylindrical, and the outer casing includes a plate portion on which one end of each of the plurality of battery cells is positioned adjacent to the inner surface, and the flow path defining member may be attached to the outer surface of the plate portion.

[0014] One end of a battery cell is positioned adjacent to the inner surface of the plate portion of the outer casing. Furthermore, a flow path defining member is attached to the outer surface of the plate portion of the outer casing, so the airflow path is defined by the flow path defining member and the outer surface of the plate portion. In other words, the outer surface of the plate portion is in direct contact with the airflow path. The heat generated by the battery cell is transferred to the inner surface of the plate portion by thermal conduction, and the outer surface of the plate portion that defines the airflow path is cooled by the cooling air.

[0015] Since a flow path defining member is attached to the outer surface of the plate portion of the outer casing, the airflow path functions as a crash zone that protects the plate portion from external forces due to the deformation of the flow path defining member. Therefore, it is possible to reduce the strength of the plate portion of the outer casing, that is, to reduce the thickness of the plate portion. By making the plate portion thinner, the heat transfer efficiency from the battery cells to the outer surface of the plate portion can be improved, and the cooling efficiency of the battery cells can be increased.

[0016] A current collection structure is provided at the other end of the battery cell, and the current collection structure is not provided at the one end of the battery cell. A thermal conductive layer made of a thermally conductive material may be interposed between the one end of the battery cell and the inner surface of the plate portion of the outer casing.

[0017] By thermally connecting the battery cell and the inner surface of the outer casing plate using a thermal conductive layer, the efficiency of heat conduction from the battery cell to the outer surface of the plate can be improved, thereby increasing the cooling efficiency of the battery cell.

[0018] An insulating layer may be further interposed between the heat conductive layer and the inner surface of the plate portion of the outer casing.

[0019] The flow path defining member may include a main body portion that is spaced apart from and directly opposite to the outer surface of the plate portion of the outer case, a rib portion provided on the main body portion that extends along the direction in which the air flow path extends and protrudes toward the outer surface of the plate portion of the outer case, and a mounting portion provided at the tip of the rib portion and attached to the outer surface of the plate portion of the outer case.

[0020] The mounting portion of the flow path defining member may be fixed to the outer surface of the plate portion of the outer case by screws.

[0021] The battery cell assembly includes a cell holder that holds the plurality of battery cells, and the male threaded portion of the screw may be screwed into the portion of the cell holder that does not hold the plurality of battery cells.

[0022] The flow path defining member may have a hat structure composed of a pair of rib portions and one mounting portion.

[0023] By incorporating a hat structure, the thickness of the main body of the flow path defining member can be reduced while ensuring the strength of the flow path defining member.

[0024] The flow path defining member may include a spacer interposed between the main body and the outer surface of the plate portion of the outer case.

[0025] The flow path defining member comprises a base attached to the outer surface of the plate portion of the outer case, a top portion spaced apart from the base, and a pair of side portions extending along the direction of the air flow path and connecting both sides of the base and the top portion, respectively, wherein the base may be provided with an opening through which the outer surface of the plate portion of the outer case directly contacts the air flow path.

[0026] The following describes specific examples of this disclosure in detail based on the drawings. In the following description, terms indicating specific directions or positions (e.g., "up," "down," and other terms including these) will be used as needed. The use of these terms is for the purpose of facilitating understanding of the disclosure with reference to the drawings, and the meaning of these terms does not limit the technical scope of this disclosure. Also, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components. Furthermore, the embodiments shown below are examples of the technical concept of this disclosure and do not limit this disclosure to them. In addition, the dimensions, materials, shapes, relative arrangements, etc. of the components described below are intended to be illustrative, and not to limit the scope of this disclosure unless specifically stated. Also, the content described in one embodiment or example is applicable to other embodiments or examples. Furthermore, the size and positional relationships of the components shown in the drawings may be exaggerated for clarity in the explanation.

[0027] The energy storage device described herein can be applied, for example, to a home energy storage device. However, the energy storage device described herein is not limited to home energy storage devices and can be applied to other energy storage devices.

[0028] In the Cartesian coordinate system shown in some of the diagrams, the X, Y, and Z directions correspond to the front-to-back, height, and width directions of the energy storage device 1, respectively.

[0029] Referring to Figures 1 to 4, the energy storage device 1 according to the embodiment of this disclosure comprises an outer case 2, a battery cell assembly 3, a current collection structure 4, and a flow path defining plate (flow path defining member) 5.

[0030] The outer casing 2 is made of metal plate and has an external appearance as a rectangular parallelepiped that is flattened in the height direction. The outer casing 2 comprises a top case 11, a front case 12, and a bottom case (plate portion) 13. The top case 11, front case 12, and bottom case 13 define the internal space for housing the battery cell assembly 3. The top case 11 constitutes the top wall, side walls, and rear wall of the outer casing 2, the front case 12 constitutes the front wall of the outer casing 2, and the bottom case 13 constitutes the bottom wall of the outer casing 2. The outer casing 2 is housed in a cabinet (not shown).

[0031] As will be described in detail later, a flow path defining plate 5 is attached to the outer surface 13a of the bottom case 13. Two air passages 6 extending in the width direction (Z direction) are defined by the inner surface 5a of the flow path defining plate 5 and the outer surface 13a of the bottom case 13. Each air passage 6 has openings at both ends, with the opening at one end forming an air intake 6a and the opening at the other end forming an exhaust port 6b. The cabinet is also provided with an air intake and an exhaust port (neither of which are shown). A fan (not shown) is also placed inside the cabinet. When the fan is operating, air is drawn in from the air intake port of the cabinet and flows into the air passage 6 from the air intake port 6a. As shown by the arrow AF in Figure 1, the air flows through the air passage 6 and flows out from the exhaust port 6b, and is discharged to the outside from the exhaust port of the cabinet. This airflow cools the outer surface 13a of the bottom case 13, as will be described later, and as a result, the battery cells 21 of the battery cell assembly 3 are air-cooled.

[0032] Referring also to Figures 5 to 8, as described above, the airflow path 6 is defined by the flow path defining plate 5 and the outer surface 13a of the bottom case 13 of the outer case 2. In other words, the outer surface 13a of the outer case is in direct contact with the airflow path 6. Therefore, the cooling efficiency of the battery cells 21 (see Figure 9) of the battery cell assembly 3 housed in the outer case 2 can be ensured by air cooling.

[0033] The air passage 6 also functions as a crush zone, absorbing external forces to some extent by the deformation of the air passage defining plate 5 when external forces are applied to the energy storage device 1 before installation (for example, during transportation). Therefore, the external forces applied to the energy storage device 1 do not directly act on the bottom case 13 of the outer case 2, effectively protecting the battery cells 21 of the battery cell assembly 3 housed in the outer case 2 from external forces. In this way, the air passage 6 combines its original air cooling function with the function of a crush zone. Therefore, while ensuring protection of the battery cells 21 from external forces, it is possible to miniaturize the energy storage device 1, or more specifically, reduce the dimensions of the energy storage device 1 in the height direction (Y direction).

[0034] The flow path defining plate 5 is attached to the outer surface 13a of the bottom case 13, and the air flow path 6 is provided on the outside of the outer case 2. In other words, the air flow path 6 is fluidically isolated from the internal space of the outer case 2. This isolation prevents foreign matter from entering the internal space of the outer case 2 via the air flow path 6, so there is no need to provide filters to prevent foreign matter from entering the air intake port 6a and exhaust port 6b of the air flow path 6, and the structure of the energy storage device 1 can be simplified.

[0035] Since an airflow path 6 is provided by attaching a flow path defining plate 5 to the outer surface 13a of the bottom case 13, the only things that need to be provided in the cabinet for air cooling are a space or flow path that allows air to flow from the cabinet's air intake through the fan to the air intake 6a of the airflow path 6, and a space or flow path that allows air to flow from the exhaust port 6b of the airflow path 6 to the cabinet's exhaust port. Therefore, the design of the cabinet can be simplified and costs can be reduced.

[0036] Referring to Figures 3, 4, and 5 through 9, the battery cell assembly 3 comprises a plurality of battery cells 21 (shown only in Figure 9), a cell holder 23, and a substrate holder 24. The cell holder 23 and the substrate holder 24 are made of resin.

[0037] Referring to Figure 9, each battery cell 21 is a cylindrical lithium-ion secondary battery and has a pair of end faces 21a and 21b and a side face 21c. The battery cell 21 may be a battery other than a lithium-ion secondary battery, such as an all-solid-state battery. One end face 21a is provided with a peripheral electrode 21d as a negative electrode at its periphery and a central electrode 21e as a positive electrode in the center. The polarity of the peripheral electrode 21d and the central electrode 21e may be reversed. The other end face 21b is not provided with an electrode and is generally flat.

[0038] Referring to Figures 3, 4, and 5 through 9, the cell holder 23 has a split structure comprising an upper holder 25 and a lower holder 26, each provided with multiple housing holes 23a that house and hold one battery cell 21. Each battery cell 21 is held in the cell holder 23 with its end face 21a, which has peripheral electrodes 21d and a central electrode 21e, facing the top wall of the outer case 2 of the top case 11, and its opposite end face 21b facing the bottom case 13. Furthermore, for each battery cell 21, the end face 21a is exposed from the upper holder 25, and the end face 21b is exposed from the lower holder 26.

[0039] As shown in Figure 3, in this embodiment, a total of 280 battery cells 21 are held in the cell holder 23. More specifically, 14 battery cells 21 arranged in the front-to-back direction (X direction) form one row, and a total of 20 such rows are arranged in the width direction (Z direction).

[0040] Referring to Figures 4 and 9, the current collection structure 4 connects 14 battery cells 21 forming a row in the front-to-back direction (X direction) in parallel, and also provides four groups of battery cells, each consisting of five rows of battery cells 21 connected in series, and connects these four groups of battery cells in series. For example, as shown in Figure 9, at one end of the energy storage device 1 in the width direction (Z direction), the current collection structure 4 forms one group of battery cells with a busbar 41 that connects the peripheral electrodes 21d of the 14 battery cells 21 in the row closest to the end in the width direction in parallel, and busbars 42, 43, 44, 45, 46, 47 that connect the central electrodes 21e of another row of 14 battery cells 21 in parallel and connect the next adjacent row of 14 battery cells 21 in parallel. The current collection structure 4 also includes a busbar 48 that connects this battery cell group 31 to the next adjacent battery cell group 31.

[0041] The substrate holder 24 is provided along the front-to-back (X-direction) end of the cell holder 23, more specifically along the end on the front case 12 side, and is fixed to the cell holder 23. The substrate holder 24 houses the substrate 27.

[0042] Referring to Figure 5, a space 51 is provided between the cell holder 23 and the portion of the front wall of the outer case 2 of the top case 11. A side plate (not shown) is also positioned between the cell holder 23 and the portion of the front wall of the outer case 2 of the top case 11. Furthermore, a space 52 is provided between the cell holder 23 and the front case 12, and the substrate holder 24 is positioned in this space 52. Space 51 functions as a crash zone that absorbs to some extent the external force applied to the energy storage device 1 due to the deformation of the top case 11. Similarly, space 52 functions as a crash zone that absorbs to some extent the external force applied to the energy storage device 1 due to the deformation of the front case 12.

[0043] Referring to FIGS. 3 to 8, particularly FIGS. 5 to 8, the end face portion 21b on the side opposite to the end face portion 21a provided with the peripheral electrode 21d and the central electrode 21e of each battery cell 21 is disposed adjacent to the inner surface 13b of the bottom case 13. A heat transfer sheet (heat transfer layer) 7 and an insulating plate (insulating layer) 8 are provided between the end face portion 21a of each battery cell and the inner surface 13b of the bottom case 13. More specifically, the heat transfer sheets 7 (four sheets in this embodiment) are arranged so as to adhere to the end face portion 21a of the battery cell 21, and an insulating plate 8 is interposed between the heat transfer sheet 7 and the inner surface 13b of the bottom case 13.

[0044] The heat transfer sheet 7 is made of a heat conductive material (TIM), which is a material having a higher thermal conductivity than at least the insulating resin constituting the cell holder 23. As an example of the heat conductive material, a silicon-based material containing a heat conductive filler can be cited. This heat conductive material has a certain degree of elasticity or flexibility.

[0045] Referring to FIGS. 10 and 11, the flow path defining plate 5 in this embodiment is made of a metal plate and includes two main body portions 5b, four rib portions 5c, and three mounting portions 5d.

[0046] Referring to FIGS. 1, 5 to 8 together, the two main body portions 5b of the flow path defining plate 5 are each flat plate-shaped without openings extending in the front-rear direction (X direction) and the width direction (Z direction) of the power storage device 1. Each main body portion 5b faces the outer surface 13a of the bottom case 13 at an interval directly, that is, without any other members intervening. For example, as shown in FIG. 5, each main body portion 5b is substantially parallel to the outer surface 13a of the bottom case 13.

[0047] The four rib portions 5c of the flow path defining plate 5 each extend along the extending direction of the air flow path 6 (see the arrow AF in FIG. 1) and project in the height direction (Y direction) of the power storage device 1 from the main body portion 5b toward the outer surface 13a of the bottom case 13. Two rib portions 5c are provided at the ends in the front-rear direction (X direction) of the power storage device 1 of the main body portion 5b. The remaining two rib portions 5c are provided at the central portion in the front-rear direction (X direction) of the power storage device 1 of the main body portion 5b.

[0048] The three mounting portions 5d of the flow path defining plate 5 each project in the front-rear direction (X direction) of the power storage device 1 at the tip of the rib portion 5c and extend in the width direction (Z direction) of the power storage device 1. As will be described in detail later, in the present embodiment, the mounting portion 5d is attached to the outer surface 13a of the bottom case 13 by screwing. Therefore, the mounting portion 5d is provided with a through hole 5e for inserting the male screw portion 54b of the male screw 54 described later.

[0049] As most clearly shown in FIG. 5, each air flow path 6 is defined by one main body portion 5b, a pair of rib portions (5c) facing each other in the front-rear direction (X direction) of the power storage device 1, and the outer surface 13a of the bottom case 13. The height of the rib portion 5c is set low, the shape of the cross section orthogonal to the extending direction of each air flow path 6 (see the arrow AF in FIG. 1) is constant, and it is flat in the height direction (Y direction) of the power storage device 1 and elongated in the front-rear direction (X direction) in a rectangular shape. By each air flow path 6 having such a cross-sectional shape, while ensuring the flow rate of the cooling air passing through the air flow path 6, the dimension in the height direction (Y direction) of the power storage device 1 can be reduced, and the power storage device can be miniaturized.

[0050] Referring to FIGS. 3 to 8, the heat generated in each battery cell 21 is transmitted from the end face portion 21b on the side opposite to the end face portion 21a provided with the peripheral electrode 21d and the central electrode 21e to the heat transfer sheet 7, and further transmitted to the inner surface 13b of the bottom case through the insulating plate 8. And since the outer surface 13a of the bottom case 13 is directly in contact with the air flow path 6 as described above, it is cooled by the air flowing through the air flow path 6, and as a result, the battery cell is air-cooled.

[0051] As described above, a heat transfer sheet 7 is interposed between the inner surface 13b of the bottom case 13 and the end face portion 21b of the battery cell 21, and the heat transfer sheet 7 is in close contact with the end face portion 21b of the battery cell 21. Thus, by thermally connecting the battery cell 21 and the inner surface 13b of the bottom case 13 by the heat transfer sheet 7, the heat conduction efficiency from the battery cell 21 to the outer surface 13a of the bottom case 13 can be improved, and the cooling efficiency of the battery cell 21 can be enhanced.

[0052] As mentioned above, since the flow path defining plate 5 is attached to the outer surface 13a of the bottom case 13, the air flow path 6 functions as a crush zone that protects the bottom case 13 from external forces due to the deformation of the flow path defining plate 5. Therefore, it is possible to reduce the strength of the bottom case 13, that is, to reduce the thickness of the bottom case 13. By making the bottom case 13 thinner, the heat transfer efficiency from the battery cell 21 to the outer surface 13a of the bottom case 13 can be improved, and the cooling efficiency of the battery cell 21 can be increased.

[0053] Referring to Figures 1, 5, and 7, the flow path defining plate 5 is provided with a hat structure 53 extending in the width direction (Z direction) of the energy storage device 1. This hat structure 53 is composed of a pair of rib portions 5c and one mounting portion 5d in the center of the energy storage device 1 in the front-to-back direction (X direction). By providing the hat structure 53, the thickness of the main body portion 5b can be reduced while ensuring the strength of the flow path defining plate 5.

[0054] The screw fastening structure of the flow path definition plate 5 will be explained with reference to Figures 1, 3, 4, and 5 to 8.

[0055] As shown in Figures 5 to 8, the head 54a of the male screw 54 is located on the mounting portion 5d of the flow path defining plate 5, and the male thread portion 54b of the male screw 54 is inserted through the through hole 5e provided in the mounting portion 5d. The lower holder 26 of the cell holder 23 has female threaded holes 26d in the boss portions 26a, 26b, and 26c, which are the parts that do not hold the electronic cell 21. The boss portions 26a and 26c are provided at both ends of the lower holder 26 in the width direction (Z direction) of the energy storage device 1. The boss portion 26a is provided in the center of the lower holder 26 in the width direction (Z direction) of the energy storage device 1. The male thread portion 54b of the male screw 54 is screwed into the female threaded hole 26d. In other words, the mounting portion 5d of the flow path defining plate 5 is fixed to the boss portions 26a, 26b, and 26c of the lower holder 26 by a male screw 54, and the heat transfer sheet 7 and insulating plate 8 are sandwiched and held between the lower holder 26 and the inner surface 13b of the bottom case 13. Referring together to Figures 3 and 4, the bottom case 13 and insulating plate 8 are provided with through holes 13c and 8a for inserting the male screw portion 54b of the male screw 54. In addition, gaps are provided between the four insulating sheets 7 to allow the male screw portion 54b of the male screw 54 to pass through.

[0056] The attachment of the mounting portion 5d of the flow path defining plate 5 to the outer surface 13a of the bottom case 13 is not limited to screw fastening, but other fastening means such as welding or adhesive can be used.

[0057] This disclosure is not limited to embodiments and various modifications are possible. For example, there are modifications shown in Figures 12 to 16.

[0058] In the first modified example shown in Figure 12, the flow path defining plate 5 is not provided with a hat structure 53 (see, for example, Figure 5), and a single air flow path 6 is defined by the flow path defining plate 5 and the outer surface 13a of the bottom case 13.

[0059] In the second modified example shown in Figure 13, the main body 5b of the flow path defining plate 5 is provided with a recess 5f that protrudes toward the inner surface 5a. By providing such a recess 5f, the cross-sectional area of ​​the air flow path 6 can be partially reduced. For example, by providing such a recess 5f so as to face the portion of the lower holder 26 that does not hold the battery cell 21, the airflow rate in the portion facing the battery cell 21 can be relatively increased, thereby improving the air cooling effect.

[0060] In the third modified example shown in Figure 14, the flow path defining plate 5 does not have a hat structure 53 (see, for example, Figure 5). Instead of the hat structure 53, a spacer 56 is placed between the outer surface 13a of the bottom case 13 and the main body 5b of the flow path defining plate 5 to maintain the distance between them.

[0061] In the fourth modified example shown in Figures 15 and 16, a flow path defining cylinder 57 is provided instead of the flow path defining plate 5 of this embodiment to define the air flow path 6. The flow path defining cylinder 57 is a flat rectangular tube with openings at both ends, and comprises a base portion 57a, a top portion 57b, and a pair of side portions 57c. The base portion 57a ​​is attached to the outer surface 13a of the bottom case 13 of the outer case 2 (see, for example, Figure 1). Similar to the embodiment, the base portion 57a ​​has a tab-shaped portion 57e with a through hole 57d for attachment to the outer surface 13a of the bottom case 13 by screw fastening. The top portion 57b faces the base portion 57a ​​with a gap in the height direction (Z direction) of the energy storage device 1. The pair of side portions 57c extend along the direction of extension of the air flow path 6 and connect both sides of the base portion 57a ​​and the top portion 57b, respectively. An opening 57f is provided in the base portion 57a, and the outer surface 13a of the bottom case 13 of the outer case 2 is in direct contact with the air passage through this opening 57f.

[0062] In the description of each embodiment, expressions such as parallel, perpendicular, orthogonal, identical, and equal include not only strictly parallel, perpendicular, orthogonal, identical, and equal, but also substantially parallel, perpendicular, orthogonal, identical, and equal.

[0063] This disclosure may include the following aspects:

[0064] (Aspect 1) An energy storage device comprising: an outer case; a battery cell assembly housed within the outer case and comprising a plurality of battery cells; and a flow path defining member attached to the outer surface of the outer case, which defines an air flow path together with the outer surface of the outer case, having an air intake port and an exhaust port, and configured such that cooling air flows from the air intake port to the exhaust port.

[0065] (Aspect 2) The energy storage device according to aspect 1, wherein each of the plurality of battery cells is cylindrical, the outer case has a plate portion on which one end of each of the plurality of battery cells is arranged adjacent to the inner surface, and the flow path defining member is attached to the outer surface of the plate portion.

[0066] (Aspect 3) The energy storage device according to aspect 2, wherein a current collection structure is provided at the other end of the battery cell, the current collection structure is not provided at the one end of the battery cell, and a thermal conductive layer made of a thermal conductive material is interposed between the one end of the battery cell and the inner surface of the plate portion of the outer case.

[0067] (Aspect 4) The energy storage device according to aspect 3, wherein an insulating layer is further interposed between the heat conductive layer and the inner surface of the plate portion of the outer case.

[0068] (Aspect 5) The energy storage device according to any one of aspects 1 to 4, wherein the flow path defining member comprises: a main body portion that is spaced apart from and directly opposite to the outer surface of the plate portion of the outer case; a rib portion provided on the main body portion that extends along the direction of extension of the air flow path and protrudes toward the outer surface of the plate portion of the outer case; and a mounting portion provided at the tip of the rib portion and attached to the outer surface of the plate portion of the outer case.

[0069] (Aspect 6) The energy storage device according to aspect 5, wherein the mounting portion of the flow path defining member is fixed to the outer surface of the plate portion of the outer case by screws.

[0070] (Aspect 7) The energy storage device according to aspect 5, wherein the battery cell assembly comprises a cell holder for holding the plurality of battery cells, and the male threaded portion of the screw is screwed into the portion of the cell holder that does not hold the plurality of battery cells.

[0071] (Aspect 8) The energy storage device according to aspect 5, wherein the flow path defining member comprises a hat structure composed of a pair of rib portions and one mounting portion.

[0072] (Aspect 9) The energy storage device according to aspect 5, wherein the flow path defining member includes a spacer interposed between the main body and the outer surface of the plate portion of the outer case.

[0073] (Aspect 10) The energy storage device according to any one of aspects 1 to 4, wherein the flow path defining member comprises a base attached to the outer surface of the plate portion of the outer case, a top portion facing the base portion at a distance from it, and a pair of side portions extending along the direction of extension of the air flow path and connecting both sides of the base portion and the top portion, and the base portion is provided with an opening through which the outer surface of the plate portion of the outer case directly contacts the air flow path.

[0074] 1. Energy storage device 2. Outer case 3. Battery cell assembly 4. Current collection structure 5. Flow path defining plate (flow path defining member) 5a. Inner surface 5b. Main body 5c. Rib part 5d. Mounting part 5e. Through hole 5f. Recess 6. Air flow path 6a. Air intake port 6b. Exhaust port 7. Heat transfer sheet (heat transfer layer) 8. Insulating plate (insulating layer) 8a. Through hole 11. Top case 12. Front case 13. Bottom case (plate part) 13a. Outer surface 13b. Inner surface 13c. Through hole 21. Battery cell 21a, 21b. End surface 21c. Side surface 21d. Peripheral electrode 21e. Central electrode 23. Cell holder 23a. Housing hole 24. Substrate holder 25. Upper holder 26. Lower holder 26a, 26b, 26c Boss part 26d Female screw hole 27 Substrate 31 Battery cell group 41-47 Busbar 51, 52 Space 53 Hat structure 54 Male screw 54a Head 54b Male screw part 56 Spacer 57 Flow path defining cylinder (flow path defining member) 57a Base part 57b Top part 57c Side part 57d Through hole 57e Tab-shaped part 57f Opening

Claims

1. An energy storage device comprising: an outer casing; a battery cell assembly housed within the outer casing and comprising a plurality of battery cells; and a flow path defining member attached to the outer surface of the outer casing and having an air intake port and an exhaust port, which together define an air flow path configured such that cooling air flows from the air intake port to the exhaust port, in conjunction with the outer surface of the outer casing.

2. The energy storage device according to claim 1, wherein each of the plurality of battery cells is cylindrical, the outer casing comprises a plate portion on which one end of each of the plurality of battery cells is arranged adjacent to the inner surface, and the flow path defining member is attached to the outer surface of the plate portion.

3. The energy storage device according to claim 2, wherein a current collection structure is provided at the other end of the battery cell, the current collection structure is not provided at the one end of the battery cell, and a thermal conductive layer made of a thermally conductive material is interposed between the one end of the battery cell and the inner surface of the plate portion of the outer casing.

4. The energy storage device according to claim 3, wherein an insulating layer is further interposed between the heat conductive layer and the inner surface of the plate portion of the outer casing.

5. The energy storage device according to any one of claims 1 to 4, wherein the flow path defining member comprises: a main body portion that is spaced apart from and directly opposite to the outer surface of the plate portion of the outer case; a rib portion provided on the main body portion that extends along the direction of extension of the air flow path and protrudes toward the outer surface of the plate portion of the outer case; and a mounting portion provided at the tip of the rib portion and attached to the outer surface of the plate portion of the outer case.

6. The energy storage device according to claim 5, wherein the mounting portion of the flow path defining member is fixed to the outer surface of the plate portion of the outer case by screws.

7. The energy storage device according to claim 5, wherein the battery cell assembly comprises a cell holder for holding the plurality of battery cells, and the male threaded portion of the screw is screwed into the portion of the cell holder that does not hold the plurality of battery cells.

8. The energy storage device according to claim 5, wherein the flow path defining member comprises a hat structure composed of a pair of rib portions and one mounting portion.

9. The energy storage device according to claim 5, wherein the flow path defining member includes a spacer interposed between the main body and the outer surface of the plate portion of the outer case.

10. The energy storage device according to any one of claims 1 to 4, wherein the flow path defining member comprises a base attached to the outer surface of the plate portion of the outer case, a top portion facing the base portion at a distance from it, and a pair of side portions extending along the direction of extension of the air flow path and connecting both sides of the base portion and the top portion, and the base portion is provided with an opening that allows the outer surface of the plate portion of the outer case to be in direct contact with the air flow path.

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