Power storage module

Abstract

This power storage module (battery module) that accommodates a plurality of power storage devices (batteries) includes: a holder that accommodates one end side of the plurality of power storage devices to separate and hold the plurality of power storage devices from each other; a plurality of rod-shaped portions that are disposed between a pair of power storage devices among the plurality of power storage devices and extend in a first direction; and a heat radiator that is disposed on the opposite surface of the plurality of power storage devices of the holder and includes a flat plate portion to which one end of each of the plurality of rod-shaped portions is connected.

Description

Energy storage module

[0001] The present disclosure relates to an energy storage module that houses a plurality of energy storage devices.

[0002] Conventionally, a power storage module accommodates multiple power storage devices, which are connected in parallel and in series to obtain a predetermined capacity and voltage. Power storage devices include secondary batteries such as lithium-ion batteries and capacitors.

[0003] In conventional energy storage modules, the energy storage device generates heat in response to charging and discharging, etc., and this heat needs to be cooled. Furthermore, if an abnormality occurs in the energy storage device, causing a large current to flow, the energy storage device may become too hot, which may adversely affect the surrounding energy storage devices.

[0004] However, since energy storage modules used as power sources for electric bicycles, vacuum cleaners, etc. must have a small capacity and be relatively inexpensive, it is difficult to provide them with a sufficient cooling mechanism. On the other hand, there is a strong demand for smaller and lighter modules, and as the power density of the energy storage device increases, the cooling problem becomes a bigger issue.

[0005] There are various types of cooling mechanisms, but Patent Document 1 discloses that a cooling method using a coolant is adopted, and when gas is generated due to a battery abnormality, the gas is not discharged directly to the outside, but is discharged to the outside through a separate space within the battery pack, thereby preventing the coolant from leaking to the outside.

[0006] Japanese Patent Application Laid-Open No. 2008-276997

[0007] The energy storage module of the present disclosure is an energy storage module that houses a plurality of energy storage devices, and includes a holder that houses one end sides of the plurality of energy storage devices and holds the plurality of energy storage devices spaced apart from each other, a plurality of rod-shaped portions that are arranged between a pair of the plurality of energy storage devices and extend in a first direction, and a heat sink that is arranged on the surface of the holder opposite the plurality of energy storage devices and includes a flat portion to which one end of each of the plurality of rod-shaped portions is connected.

[0008] According to the present disclosure, a highly reliable energy storage module can be provided.

[0009] Fig. 1 is an exploded perspective view showing the main configuration of an energy storage module according to an embodiment; Fig. 2 is a cross-sectional view showing the main configuration of an energy storage module according to an embodiment; Fig. 3 is a cross-sectional view showing the peripheral portion of one battery 12 of an inter-cell member; Fig. 4 is an exploded perspective view showing the main configuration of another example of an energy storage module; Fig. 5 is a cross-sectional view showing the main configuration of another example of an energy storage module; Fig. 6 is a perspective view showing a modified example of a rod-shaped portion;

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following embodiments do not limit the present disclosure, and configurations formed by selectively combining multiple examples are also included in the present disclosure.

[0011] "Overall Configuration" Fig. 1 is an exploded perspective view showing the main configuration of an energy storage module according to an embodiment. Fig. 2 is a cross-sectional view showing the main configuration. In this embodiment, a cylindrical lithium-ion battery is used as an example of an energy storage device, and the energy storage module is a battery module 100 that houses a plurality of batteries 12 (lithium-ion batteries). In this disclosure, the batteries 12 may be referred to as the "energy storage device," and the battery module 100 may be referred to as the "energy storage module."

[0012] The battery 12 is cylindrical, with a positive electrode at one end and a negative electrode at the other. One example of the battery 12 configuration may include an electrode assembly formed by winding strip-shaped positive and negative electrode plates with a separator interposed therebetween, a cylindrical outer can containing the electrode assembly together with an electrolyte, a conductive seal covering the opening of the outer can, a gasket providing electrical insulation between the seal and the outer can, an internal negative electrode lead electrically connecting the negative electrode plate to the bottom of the outer can within the outer can, and an internal positive electrode lead electrically connecting the positive electrode plate to the seal. The gasket may also cover the top and bottom surfaces of the seal and the outer periphery connecting the top and bottom surfaces. The gasket may be provided on the outer periphery of the outer can and be sandwiched between a protruding groove on the inner periphery of the outer can and a crimped portion that bends the opening of the outer can inward in the direction of the winding axis of the electrode assembly to seal the inside of the outer can. The upper end of the battery 12 is housed in an upper holder 14, and the lower end is housed in a lower holder 16. Hereinafter, when the contents of both the upper holder 14 and the lower holder 16 are common to both, they will be referred to collectively as the "holder." The upper holder 14 and the lower holder 16 are similarly shaped and have multiple storage compartments that respectively cover the upper and lower portions of the cylindrical batteries 12. Specifically, the holder has a wall facing the end face of each battery 12 and a side wall extending along the lateral periphery of the battery 12, forming storage compartments consisting of recesses at predetermined intervals. The battery 12 is housed in these recesses. Multiple openings 18 are provided in the center of the wall, exposing the electrode terminals on the upper and lower end faces of the battery 12. The holder can be made of an insulating material, such as resin. Note that either the upper holder 14 or the lower holder 16 may have openings exposing both terminals.

[0013] In this example, four rows of four batteries 12 are provided along a given plane, for a total of 16 batteries, resulting in 16 openings 18. The four openings in one row are arranged in a straight line, but are offset by a half-pitch from the next row. Small holes 20 are provided in the area between the openings 18. In this example, six small holes 20 (also called insertion holes) are provided between the rows. Here, the group of 16 batteries 12 in Figure 1 is called a battery block 10. In this embodiment, two battery blocks (first group and second group) are arranged with a flat plate portion of a heat sink (described later) between them.

[0014] An inter-cell member 22 is disposed in the area between the multiple batteries 12 between the upper holder 14 and the lower holder 16, i.e., around the middle portion of the outer periphery of the batteries 12. The small holes 20 may be formed in the inter-cell member 22 so as to continue from the upper holder 14. The inter-cell member 22 may also be made of resin, and is preferably made of a heat insulating material. For example, a foamed resin containing air bubbles may be used. Furthermore, the elasticity of the inter-cell member allows the gaps between the batteries 12 to be filled without gaps.

[0015] A current collector plate 38 (see FIG. 2 ) is disposed on the wall of each of the upper and lower holders 14 and 16, opposite the surface facing the batteries 12. The current collector plate 38 has a lead 38a at a position corresponding to the opening 18 of the upper holder 14, and this lead 38a connects to an electrode terminal (e.g., a positive terminal) located on the top surface of the batteries 12. The current collector plate 38 connects multiple electrode terminals to connect the positive electrodes of multiple batteries 12 in parallel. For example, by connecting a current collector plate connected to the negative electrode of one set of batteries 12 to a current collector plate connected to the positive electrode of another set, one set of parallel-connected batteries 12 can be connected in series with another set of parallel-connected batteries 12. For example, one row of four batteries 12 can be connected in parallel, and four rows can be connected in series. In this case, the current collector 38 in the first row is a positive current collector, and the current collector in the last row is a negative current collector, with a positive terminal connected to the positive current collector and a negative terminal connected to the negative current collector.

[0016] The heat sink 30 is then disposed on the current collecting plate 38. As shown in FIG. 2 , the heat sink 30 includes multiple rod-shaped portions 32 that pass through small holes 20 in the upper holder 14 and the inter-cell member 22 and extend (in a first direction) along the side surfaces of the multiple batteries 12, and a flat plate portion 34 that is disposed on the surface of the holder wall opposite the surface facing the multiple power storage devices and to which one ends of the multiple rod-shaped portions 32 are connected. FIG. 2 illustrates the flat plate portion 34 disposed on the upper holder 14, with the rod-shaped portions 32 extending downward. However, the flat plate portion 34 may be disposed below the lower holder 16, with the rod-shaped portions 32 extending upward, or both. The rod-shaped portions 32 may extend along the entire side of the batteries 12 or only partially. In the power storage module of the present disclosure, the flat plate portion of the heat sink may be disposed between the current collecting plate and the holder.

[0017] In this example, the rod-shaped portion 32 has a portion 32c (first region) that is inserted into the small hole 20 and a large-diameter portion 32a (second region) that is thicker than the first region at its base, which is connected to the flat plate portion 34. Because the diameter of the large-diameter portion 32a is larger than that of the small hole 20, it is not inserted into the small hole 20. Therefore, a space equal to the length of the large-diameter portion 32a can be secured between the upper holder 14 and the flat plate portion 34. A current collecting plate 38 is disposed in this space between the upper holder 14 and the flat plate portion 34.

[0018] Similarly, a lower current collecting plate 38 and a lower heat sink 30 can be provided below the lower holder 16. In this case, the rod-shaped portion 32 of the lower heat sink 30 extends upward from below. The tip of the upper rod-shaped portion 32 can reach approximately the same position as the tip of the lower rod-shaped portion 32.

[0019] The batteries 12, upper holder 14, lower holder 16, inter-cell members 22, current collector plates 38, heat sink 30, etc. are housed in a case 50. The case 50 houses these components and also has positive and negative terminals for the battery module 100, allowing connection to an external circuit.

[0020] As described above, this embodiment has a heat sink 30 including a flat plate portion 34 and a rod-shaped portion 32, with the rod-shaped portion 32 extending between adjacent batteries 12 through small holes 20 provided in the upper holder 14 and inter-cell member 22. The heat sink 30 is made of a material with higher thermal conductivity than the upper holder 14, lower holder 16, and inter-cell member 22. Therefore, heat received by the rod-shaped portion 32 is quickly transferred to the flat plate portion 34. The flat plate portion 34 has its top and side surfaces in contact with the case 50. At least a portion of the flat plate portion 34 is in contact with the case 50. Therefore, heat from the rod-shaped portion 32 can also be diffused into the case.

[0021] When one battery 12 generates heat due to an abnormality such as an internal short circuit and reaches a high temperature, the inter-cell member 22 prevents the heat from being transferred to the surrounding area, particularly to adjacent batteries 12, but it is difficult to completely insulate the inter-cell member 22. In this embodiment, in such a case, the heat sink 30 receives and diffuses some of the heat, thereby preventing the heat from the battery 12 that has reached a high temperature due to the abnormality from being transferred to the surrounding batteries 12. Therefore, it is possible to effectively prevent the surrounding batteries 12 from becoming too hot and causing an abnormality.

[0022] 3 is a cross-sectional view showing the peripheral portion of one battery 12 in the inter-cell member 22. As described above, the central battery 12 is surrounded by six other batteries 12, and is configured to fill the gaps between them. Small holes 20 are located at the intermediate positions between adjacent batteries 12.

[0023] 1, inter-cell members 22 are also located outside the peripheral batteries 12, but no small holes 20 are provided there, and no rod-shaped portions 32 of the heat sinks 30 are arranged there. This is because the case 50 is located outside the peripheral batteries 12, and heat is transferred to the case 50. However, in the energy storage module of the present disclosure, the rod-shaped portions 32 may also be arranged outside the peripheral batteries 12.

[0024] Another Configuration Example Fig. 4 is an exploded perspective view illustrating the main part of another configuration example, and Fig. 5 is a cross-sectional view of the main part. In Fig. 4, the current collector plate 38 is not shown.

[0025] In this example, two battery blocks (first group, second group) are arranged across the flat plate portion 34 of the heat sink 30. To achieve this, rod-shaped portions 32 extend from both sides of the flat plate portion 34 of the heat sink 30. For example, the rod-shaped portion 32 on one side of the heat sink 30 is inserted into one battery block 10. Then, another battery block 10 is inserted into the rod-shaped portion 32 on the other side of the heat sink 30. In this case, connecting the battery blocks 10 so that the negative terminal of one battery block 10 is positioned above the positive terminal of the other battery block 10 simplifies the wiring (not shown). Furthermore, when connecting batteries in series within a single battery block 10, the current collector 38 that connects the first battery 12 in one battery block 10 in parallel can be connected with the current collector 38 that connects the last battery 12 in another battery block in parallel by wiring.

[0026] In this example, the heat sink 30 not only performs the heat dissipation function as in the above case, but also functions to facilitate assembly. That is, when connecting one battery block 10 to the next, if the heat sink 30 is inserted into the previous battery block 10, the positioning of the next battery block 10 can be easily performed.

[0027] "Structure of the rod-shaped portion" In the above example, the rod-shaped portion 32 of the heat sink 30 is, for example, a long, thin cylinder. However, the rod-shaped portion may have an uneven outer surface. The shape of the rod-shaped portion 32 may be other shapes, such as a polygonal prism in cross section.

[0028] 6 is a perspective view showing modified examples of the rod-shaped portion 32. (a) is a cross-shaped cross section, (b) is a star-shaped cross section, (c) is a cylinder with a circular cross section, (d) is a cylinder with slightly larger-diameter ring-shaped bulges 32b formed on the outer surface thereof and bulging outward in the radial direction at two locations along the length, and (e) is a cylinder with a larger diameter portion 32a formed at the base.

[0029] Cross-sectional shapes such as those shown in (a) and (b) facilitate increasing the contact area of ​​the rod-shaped portion with the inter-cell member. Furthermore, gaps can be easily formed between the rod-shaped portion and the small holes, which can be used as passages for gases and the like. In (d), when the inter-cell member is filled so as to cover the entire surface of the rod-shaped portion, the bulging portion 32b increases the contact area of ​​the rod-shaped portion with the inter-cell member. Alternatively, when a hole is formed in the inter-cell member and the rod-shaped portion shown in (d) is inserted into the hole, the contact area between the inter-cell member and the contact member is reduced, thereby suppressing heat transfer to the adjacent energy storage device through the rod-shaped portion. Furthermore, when the portion of the rod-shaped portion shown in (d) other than the bulging portion is thinner than the rod-shaped portion shown in (c), longitudinal movement of the rod-shaped portion 32 can be restricted. In (e), as described above, the large-diameter portion 32a maintains a predetermined space between the holder and the flat portion 34 of the heat sink 30.

[0030] In either case, it is preferable that the inter-cell member 22 has a certain degree of elasticity and contacts the outer circumferential surface of the rod-shaped portion 32 over a relatively large area. The inter-cell member may be a slurry filled in the gap between adjacent power storage devices and hardened by drying or other methods. The inter-cell member may also be made of a hard material. The inter-cell member may contain a heat absorbing material.

[0031] REFERENCE SIGNS LIST 10 Battery block 12 Battery (electricity storage device) 14 Upper holder 16 Lower holder 18 Opening 20 Small hole 22 Inter-cell member 30 Heat sink 32 Rod-shaped portion 32a Large diameter portion (second region) 32b Bulging portion 32c Portion 32c (first region) 34 Flat portion 38 Current collector plate 38a Lead 50 Case 100 Battery module

Claims

1. A power storage module that houses a plurality of power storage devices, comprising: a holder that holds the plurality of power storage devices while separating them from each other; a plurality of rod-shaped parts that are arranged between a pair of the power storage devices among the plurality of power storage devices and extend in a first direction; and a flat plate part to which one end of each of the plurality of rod-shaped parts is connected, the flat plate part being a heat sink.

2. The power storage module according to claim 1, wherein the heat sink is made of a material having higher thermal conductivity than the holder.

3. The power storage module according to claim 1, wherein a concave part or a convex part is formed on a side circumferential surface of each of the plurality of rod-shaped parts.

4. Each of the plurality of rod-shaped parts has a first region arranged in the first direction and a second region, the second region is located closer to the flat plate part than the first region, and the second region has a larger diameter than the first region. The power storage module according to claim 1.

5. Each of the plurality of power storage devices is cylindrical. The power storage module according to claim 1.

6. The plurality of power storage devices are arranged along a predetermined plane, and the first direction is perpendicular to the predetermined plane. The power storage module according to claim 1.

7. Further comprising another plurality of rod-shaped parts, the plurality of power storage devices include a first group of a plurality of power storage devices and a second group of a plurality of power storage devices, the flat plate part has a first surface connected to the plurality of rod-shaped parts and a second surface located opposite to the first surface, the first group of the plurality of power storage devices faces the first surface of the flat plate part, the second group of the plurality of power storage devices faces the second surface of the flat plate part, and the another plurality of rod-shaped parts extend further from the second surface. The power storage module according to claim 1.

8. Further comprising a case that houses the plurality of power storage devices, the holder, and the heat sink, and the flat plate part of the heat sink is in contact with or connected to the case. The power storage module according to claim 1.

9. The holder includes a housing part that houses one end of the plurality of power storage devices and an inter-cell member that surrounds a side surface of the plurality of power storage devices, the inter-cell member is made of a material having lower thermal conductivity than the heat sink, and the plurality of rod-shaped parts of the heat sink extend in the inter-cell member. The power storage module according to any one of claims 1 to 8.

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