Electric power storage module

Abstract

This electric power storage module is characterized by comprising: a plurality of power storage devices 10; a holder 30 holding the plurality of power storage devices 10; a cooling liquid for immersing the plurality of power storage devices 10 in the holder 30; and a case 40 that has an inflow portion 47 allowing the inflow of the cooling liquid from the outside, the case 40 housing the holder 30.

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 this energy storage module, the energy storage device generates heat in response to charging and discharging, etc., and this heat needs to be cooled. For example, in a battery pack, which is an energy storage module that uses a battery as the energy storage device and accommodates a plurality of batteries, a liquid immersion cooling method that uses a fluid is known as a cooling method (see Patent Document 1).

[0004] Patent No. 6256439

[0005] Here, in order to further improve the performance of the power storage module, it is required to further improve the reliability of the power storage module.

[0006] One aspect of the present disclosure is an energy storage module, characterized by comprising a plurality of energy storage devices, a holder for holding the plurality of energy storage devices, a coolant for immersing the plurality of energy storage devices within the holder, and a case for housing the holder, the case having an inlet for allowing the coolant to flow in from the outside.

[0007] According to the present disclosure, the reliability of the energy storage module is improved.

[0008] 1 is a perspective view of a battery pack, which is an example of a storage module according to an embodiment; FIG. 2 is an exploded perspective view of a battery pack, which is an example of a storage module according to an embodiment; FIG. 3 is an axial cross-sectional view of a storage device, which is an example of an embodiment; FIG. 4 is a cross-sectional view taken along line A-A of FIG. 1, which is a diagram schematically showing the internal configuration of the battery pack; FIG. 5 is a cross-sectional view taken along line B-B of FIG. 1, which is a diagram schematically showing the internal configuration of the battery pack; FIG. 6 is a cross-sectional view taken along line C-C of FIG. 1, which is an enlarged view of the vicinity of a coupling portion; FIG. 7 is a view corresponding to FIG. 6, of a battery pack, which is another example of a storage module according to an embodiment;

[0009] 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. In addition, in the present disclosure, a battery pack in which multiple batteries are housed in a case is used as an example of an energy storage module.

[0010] The configuration of the battery pack 1 will be described with reference to Figures 1 and 2. Figure 1 is a perspective view of the battery pack 1, and Figure 2 is an exploded perspective view of the battery pack 1. For ease of explanation, the top cover 46 of the case 40 is not shown in Figure 1.

[0011] 1 and 2 , the battery pack 1 includes a plurality of power storage devices 10, a holder 30 that holds the plurality of power storage devices 10, and a case 40 that houses the holder 30. The case 40 has an inlet 47 through which an insulating coolant 50 (see FIG. 4 ) flows in from the outside, and an outlet 48 through which the coolant 50 flows out to the outside. As a result, the coolant 50 is stored inside the case 40, and at least a portion of the power storage device 10 is immersed in the coolant 50. In other words, the coolant 50 is stored in at least a portion of the gaps inside the case 40 (gaps between the power storage devices 10 and gaps between the holder 30 and the case 40).

[0012] For ease of explanation, terms indicating the front-rear, up-down, and left-right directions are used below for each component of the holder 30 and the case 40. The front-rear direction refers to the direction in which the holder 30 and the case 40 extend (first direction). The inlet 47 side of the case 40 is referred to as the "front," and the outlet 48 side of the case 40 is referred to as the "rear." The up-down direction refers to the direction along the vertical direction. The left-right direction refers to the direction (second direction) perpendicular to the front-rear direction (first direction) when viewed from above the battery pack 1. Unless otherwise specified, the left and right refer to the left and right when the battery pack 1 is viewed from the front.

[0013] The battery pack 1 is used as a power source for motor-driven electric devices such as electric vehicles, power tools, power-assisted bicycles, electric motorcycles, electric wheelchairs, electric tricycles, and electric carts. However, the use of the battery pack 1 is not limited to a specific purpose, and the battery pack 1 may also be used as a power source for various electric devices used indoors and outdoors, such as vacuum cleaners, radios, lighting devices, digital cameras, and video cameras, other than electric devices.

[0014] The energy storage device 10 may be a secondary battery using an aqueous electrolyte or a secondary battery using a non-aqueous electrolyte. The energy storage device 10 of the present disclosure may be a cylindrical battery having a cylindrical (e.g., bottomed cylindrical) outer can, or a prismatic battery having a prismatic outer can. Alternatively, the energy storage device 10 of the present disclosure may be a capacitor that is repeatedly charged and discharged. The following description will focus on the case where the energy storage device 10 is a cylindrical battery. In this embodiment, 160 energy storage devices 10 are arranged inside the holder 30.

[0015] The holder 30 has a substantially rectangular parallelepiped shape and is slightly smaller than the case 40. The holder 30 is disposed, for example, in the substantially central portion of the interior of the case 40. This forms a gap between the holder 30 and the case 40, and the coolant 50 is stored in this gap. The holder 30 may be disposed unevenly on one side of the case 40. Furthermore, gas released from the power storage device 10 flows through this gap when the power storage device 10 generates abnormal heat, for example. The holder 30 is fixed to the case 40 with screws (not shown) or the like.

[0016] The holder 30 has an upper holder 31 that houses and holds the upper side (one end) of the power storage device 10, and a lower holder 32 that holds the lower side (the other end) of the power storage device 10. The upper holder 31 and the lower holder 32 are connected to each other by screws (not shown) or the like. The upper holder 31 and the lower holder 32 also have battery holding portions 33 (see FIG. 4 ), 34, respectively, which are housing portions that cover and hold the outer circumferential surface of the power storage device 10.

[0017] The battery holding portions 33, 34 are circular when viewed from the top and bottom, and are formed to have a recess (cylindrical recess) when viewed from the front, back, and left and right. Circular through-holes 35, 36 are provided at the top and bottom of the battery holding portion 33, 34, respectively. The through-holes 35, 36 are circular holes with inner diameters smaller than the diameter (inner diameter) of the circular battery holding portions 33, 34 when viewed from the top and bottom. The centers of the battery holding portions 33, 34 and the through-holes 35, 36 are aligned with each other when viewed from the top and bottom. However, these centers may be offset from each other.

[0018] A first opening 37 is provided in the front surface 30a (first surface) of the holder 30, through which the coolant 50 flows into the holder 30. The first opening 37 faces an inlet 47 provided in the case 40 and is provided in approximately the center of the front surface 30a. The first opening 37 is substantially circular. However, the shape of the first opening 37 is not limited thereto and may be, for example, a substantially rectangular shape. As will be described in detail later, the first opening 37 and the inlet 47 are connected by a connecting portion 70. As a result, the coolant 50 flowing in through the inlet 47 flows directly into the holder 30 via the first opening 37.

[0019] Further, a second opening 38 is provided in the rear surface 30b (second surface) of the holder 30, connecting the interior of the case 40 with the interior of the holder 30. The second opening 38 allows the coolant 50 inside the holder 30 to flow out of the holder 30. As will be described in detail later, the second opening 38 has a generally rectangular shape in a plan view and is formed on both left and right ends of the rear surface 30b of the holder 30. A portion of the coolant 50 that flows into the interior of the holder 30 flows through the second opening 38 to an outflow portion 48 provided in the case 40. Further, a portion of the coolant 50 that flows into the interior of the holder 30 flows through the second opening 38 to an outer peripheral storage chamber 49 (see FIG. 6 ) formed between the holder 30 and the case 40.

[0020] The holder 30 may be made of, for example, a highly thermally conductive PPS (polyphenylene sulfide) resin, a resin containing a heat-dissipating filler, an injection-moldable thermosetting resin, etc. More specifically, the holder 30 may be made of a phenolic resin, an unsaturated polyester, an unsaturated polyester mixed with a heat-absorbing agent, etc. The holder 30 may also be made of an inorganic mineral such as mica, or a resin material mixed with an inorganic mineral such as mica.

[0021] An upper current collector 60 is disposed above the holder 30, and a lower current collector 61 is disposed below the holder 30. The upper current collector 60 and the lower current collector 61 are each made of a metal material and are fixed by being inserted into protrusions provided on the upper holder 31 and the lower holder 32, respectively. The upper current collector 60 and the lower current collector 61 are electrically connected to the energy storage device 10 via leads 62, 63 (see FIG. 4). As will be described in detail later, in this embodiment, the energy storage device 10 is disposed so that the sealing body 16 (see FIG. 3) serving as the positive electrode terminal is on the lower side. As a result, the upper current collector 60 serves as the negative electrode terminal, and the lower current collector 61 serves as the positive electrode terminal. In the battery pack 1, the parallel portions of the multiple energy storage devices connected in parallel by the current collectors are connected in series in the front-to-rear direction. In the energy storage module of the present disclosure, the direction of the series connection is not limited to this direction. The upper current collecting plate 60 and the lower current collecting plate 61 may each have a tongue portion extending from one end of each current collecting plate (one end in the left-right direction in FIG. 1 ) along the side surface of the holder, and these tongue portions may be connected to each other. In this case, the tongue portions may be connected to each other, or may be connected via another conductive member. Furthermore, the upper current collecting plate 60 and the lower current collecting plate 61, which are arranged on opposite sides of the holder, may be arranged together on one side of the holder.

[0022] The case 40 has a substantially rectangular parallelepiped shape similar to the holder 30 and accommodates the holder 30. The case 40 is made of, for example, a metal material, such as aluminum, or a resin material. The case 40 includes a main wall 41 (bottom) that forms the lower surface and extends in the front-to-rear direction, side walls 42, 43, 44, and 45 that are provided at the ends of the main wall 41 and form the front surface 40a, rear surface 40b, right surface, and left surface of the case 40, respectively, and a top lid 46 that forms the upper surface of the case 40. The main wall 41 has a rectangular shape, and the side walls (wall portions) 42, 43, 44, and 45 are formed along the edges of the four sides of the main wall 41. The case 40 may be provided with an exhaust port (not shown) for exhausting gas released from the energy storage device 10 to the outside of the case 40. Furthermore, a rib 51 that protrudes perpendicularly from the inner surface of the main wall 41 of the case 40 may be formed separately from the side walls 42 to 45. By placing and fixing the holder 30 on the rib 51, a gap is formed between the lower part of the holder 30 and the main wall 41, and the coolant 50 can be filled in this gap as well. Furthermore, if an exhaust valve is formed on the sealing plate of the electricity storage device 10, the exhaust valve can be used to efficiently exhaust air from inside the electricity storage device 10. Furthermore, if a lower current collecting plate 61 is disposed on the bottom surface of the lower holder 32, it becomes easy to bring the lower current collecting plate 61 into contact with the coolant 50, and it is also possible to cool the electricity storage device 10 via the lower current collecting plate 61.

[0023] An inlet 47 is provided on the front surface 40a (side wall 42) of the case 40, allowing the coolant 50 to flow in from the outside. An outlet 48 is provided on the rear surface 40b (side wall 43) of the case 40, allowing the coolant 50 to flow out to the outside. In this embodiment, the case 40 has one inlet 47 and one outlet 48. The inlet 47 is provided in the approximate center of the front surface 40a of the case 40, and the outlet 48 is provided below the approximate center of the rear surface 40b of the case 40. The inlet 47 and the outlet 48 each have a generally circular shape. In addition to the outlet 48, the rear surface 40b of the case 40 may be provided with a through-hole (not shown) for passing wiring devices or the like connected to the power storage device 10 or devices inside the case 40. In the power storage module of the present disclosure, the case 40 does not necessarily have to have the outlet 48. The inlet 47 may also be formed in a position other than the side wall of the case 40.

[0024] An inlet pipe (not shown) for allowing the coolant 50 to flow into the inlet pipe 47 is connected to the inlet pipe 47, and an outlet pipe (not shown) for allowing the coolant 50 to flow out of the outlet pipe 48 is connected to the outlet pipe 48. The inlet pipe and the outlet pipe form a circulation path. The coolant 50 is circulated inside the case 40 by a pump device (not shown) or the like. A heat exchanger such as heat exchange fins may be provided in the circulation path. In the power storage module of the present disclosure, the coolant 50 does not have to be circulated through the circulation path.

[0025] The coolant 50 has electrical insulation properties, which can prevent leakage of electricity between the plurality of power storage devices 10 via the coolant 50. Examples of the coolant 50 include insulating oil, transformer oil, silicone oil, and fluorine-based inert liquids such as hydrofluoroether.

[0026] Next, the energy storage device 10 constituting the battery pack 1 will be described with reference to Fig. 3. Fig. 3 is an axial (vertical) cross-sectional view of the energy storage device 10. Note that Fig. 3 illustrates the state in which the sealing body 16 is on the upper side.

[0027] As described above, the energy storage device 10 is, for example, a cylindrical battery. The energy storage device 10 includes an electrode assembly 14 in which a strip-shaped positive electrode 11 and a strip-shaped negative electrode 12 are wound with a strip-shaped separator 13 interposed therebetween, a non-aqueous electrolyte (not shown), a cylindrical outer can 15 with a bottom that houses the electrode assembly 14 and the non-aqueous electrolyte, and a sealing body 16 that closes an opening 15d of the outer can 15.

[0028] The energy storage device 10 also includes insulating plates 18, 19 disposed above and below the electrode assembly 14. In the example shown in Fig. 3, a positive electrode lead 20 joined to the positive electrode 11 passes through a through-hole in the insulating plate 18 and extends toward the sealing body 16, and a negative electrode lead 21 joined to the negative electrode 12 passes outside the insulating plate 19 and extends toward the bottom 15a of the outer can 15. The positive electrode lead 20 is connected by welding or the like to the surface of the sealing body 16 facing the electrode assembly 14, and the sealing body 16 serves as a positive electrode terminal. The negative electrode lead 21 is connected by welding or the like to the inner surface of the bottom 15a of the outer can 15, and the outer can 15 serves as a negative electrode terminal.

[0029] The outer can 15 is a cylindrical container with a bottom that is open on one axial side. The outer can 15 is made of a metal material such as iron or aluminum. The outer can 15 has a bottom 15a and a side surface 15b that forms the side surface of the energy storage device 10. The side surface 15b is the portion of the outer can 15 excluding the bottom 15a, and includes a grooved portion 15c and an opening 15d, which will be described later.

[0030] Grooved portion 15c is a portion of side surface portion 15b recessed radially inward, and is provided in an annular shape along the circumferential direction of outer can 15. Grooved portion 15c supports sealing body 16. Grooved portion 15c can be formed, for example, by spinning a portion of side surface portion 15b radially inward to recess it in an annular shape radially inward.

[0031] Opening 15d is a region of side surface 15b closer to the opening end than grooved portion 15c, and forms the opening of outer can 15. Opening 15d is bent radially inward when sealing body 16 is fixed to outer can 15 by crimping.

[0032] 3, sealing body 16 is made up of a single plate-like member. However, the configuration of sealing body 16 is not limited to this. For example, sealing body 16 may be made up of multiple members. Furthermore, sealing body 16 may have a cap that covers the top surface of power storage device 10.

[0033] A gasket 17 is disposed between the outer peripheral surface of the sealing body 16 and the inner peripheral surface of the opening of the outer can 15. The gasket 17 is a flexible insulating member that electrically insulates the sealing body 16, which is the positive electrode terminal, from the outer can 15, which is the negative electrode terminal, while ensuring the airtightness of the interior of the outer can 15 by being compressed in the vertical direction. The material of the gasket 17 is not particularly limited as long as it is a compressible insulating material, and examples that can be used include polypropylene (PP), polyphenylene sulfide (PPS), polyethylene (PE), polybutylene terephthalate (PBT), perfluoroalkoxyalkane (PFA), polytetrafluoroethylene (PTFE), and polyamide (PA).

[0034] 3, the gasket 17 is disposed between the open end of the outer can 15 and the grooved portion 15c. Note that the gasket 17 may be disposed closer to the electrode body 14 than the grooved portion 15c.

[0035] Next, the internal configuration of the battery pack 1 will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view taken along line AA in Fig. 1, and is a diagram showing a schematic diagram of the internal configuration of the battery pack 1.

[0036] As shown in Fig. 4, the power storage device 10 is arranged inside the holder 30 with the sealing body 16 facing downward. The liquid level of the coolant 50 is located above the level of the gasket 17 (see Fig. 3). In this embodiment, as described above, the gasket 17 is arranged between the open end of the outer can 15 and the grooved portion 15c. Therefore, the liquid level of the coolant 50 is located above the grooved portion 15c. In other words, at least the side of the power storage device 10 below the grooved portion 15c is immersed in the coolant 50.

[0037] When the energy storage device 10 becomes abnormally hot, the temperature of the coolant 50 adjacent to the energy storage device 10 also rises. In this case, the temperature of the coolant 50 stored in the upper part of the case 40 tends to be higher than the temperature of the coolant 50 stored in the lower part of the case 40. When the temperature of the coolant 50 rises, it becomes difficult to sufficiently cool the energy storage device 10. Alternatively, coolant (or vaporized coolant) stored in the upper part of the case 40 at a temperature above a predetermined level may thermally affect the energy storage device 10. As a result, the temperature of the gasket 17 constituting the energy storage device 10 increases, possibly causing the gasket 17 to melt. Melting of the gasket 17 would result in insufficient insulation between the outer can 15 and the sealing body 16, which is undesirable from the viewpoint of ensuring the reliability of the battery pack 1.

[0038] In this embodiment, by positioning the energy storage device 10 so that the sealing body 16 is on the lower side and by positioning the liquid level of the coolant 50 above the gasket 17, it is possible to keep the heated coolant away from the gasket 17. This makes it easier to cool the gasket 17 when the energy storage device 10 abnormally heats up, and prevents the gasket 17 from melting. This improves the reliability of the battery pack 1. Furthermore, by disposing the coolant 50 in the gap between the holder 30 and the main wall 41, it is possible to increase the amount of coolant disposed around the gasket 17, making it less likely for the temperature of the coolant near the gasket 17 to rise.

[0039] The liquid level of the coolant 50 is preferably above the electrode body 14, and more preferably above the electricity storage device 10, i.e., the entire electricity storage device 10 is immersed in the coolant 50. By increasing the liquid level of the coolant 50, the gasket 17 can be cooled more effectively, thereby improving the reliability of the battery pack 1. In the example shown in FIG. 4 , the coolant 50 is filled throughout the case 40. By filling the case 40 with the coolant 50 throughout the case 40, the gasket 17 can be further cooled, and the reliability of the battery pack 1 can be further improved.

[0040] Next, an example of the arrangement of the power storage devices 10 and the holder 30 inside the case 40 will be described with reference to Figures 5 and 6. Figures 5 and 6 are cross-sectional views taken along line B-B in Figure 1, and are diagrams that schematically show an example of the internal configuration of the battery pack 1. Note that in Figures 5 and 6, the power storage devices 10 included in a first power storage device group 100 (described later) are shown hatched, and the power storage devices 10 included in a second power storage device group 110 are shown without hatching.

[0041] 5 and 6 , the spacing between adjacent pairs of the power storage devices 10 among the plurality of power storage devices 10 arranged inside the holder 30 may be greater than the spacing between other adjacent pairs of the power storage devices 10. In other words, the spacing between the power storage devices 10 among the plurality of power storage devices 10 may not be uniform, and the power storage devices 10 may be unevenly distributed within the holder 30. This allows an appropriate gap to be provided between the power storage devices 10, making it easier for the coolant 50 that has flowed into the holder 30 to flow inside the holder 30, and enabling the power storage devices 10 to be cooled efficiently.

[0042] In the example shown in FIG. 5 , multiple rows of the power storage devices 10 are formed inside the holder 30, aligned in the left-right direction of the battery pack 1. The multiple rows are aligned in the front-rear direction of the battery pack 1. A first power storage device group 100 and a second power storage device group 110, each consisting of a portion of these multiple rows, are arranged side by side in the front-rear direction (first direction). In each of the first power storage device group 100 and the second power storage device group 110, the power storage devices 10 are aligned with a predetermined gap (first gap) between them. A gap (second gap) larger than the gap between the power storage devices 10 is provided between the first power storage device group and the second power storage device group in the front-rear direction. This second gap may be in communication with the first gap. Due to the presence of this second gap, when the coolant in the holder 30 flows through the holder 30 for some reason, the coolant in each first gap can merge in the second gap. This merging makes it possible to make the temperature of the coolant more uniform.

[0043] Furthermore, a protrusion (fixing portion 52) protruding in a direction perpendicular to the front-to-rear direction may be provided in this second gap. This protrusion causes the coolant flowing through the second gap to collide with this protrusion, making it easier for convection to occur near this protrusion. This convection promotes equalization of the temperature of the coolant in the second gap. This protrusion may also be used as the fixing portion 52, serving as a fixing point between the holder 30 and the case 40 or a fixing point between the upper holder 31 and the lower holder 32. In this case, the protrusion serving as the fixing portion 52 may be cylindrical with a bottom. Fastening may be performed at the bottom of this protrusion.

[0044] 6 , a first power storage device group 100 and a second power storage device group 110, each including a plurality of power storage devices 10 and having different arrangements of the power storage devices 10, are arranged inside the holder 30. The first power storage device group 100 and the second power storage device group 110 each include, for example, 20 power storage devices 10.

[0045] The first energy storage device group 100 includes 20 energy storage devices 10 arranged in pairs in a staggered pattern with a gap between each pair in the left-right direction. Furthermore, in the first energy storage device group 100, the gap between the energy storage devices 10 arranged toward the center in the left-right direction is larger than the gap between the energy storage devices 10 arranged on the outer sides in the left-right direction. That is, the coolant 50 flows more easily toward the center in the left-right direction of the first energy storage device group 100 than toward the outer sides in the left-right direction. In a battery pack in which the gaps between the energy storage devices 10 are uniform throughout, when the coolant 50 is supplied into the case 40 by flowing it in the front-to-rear direction, the coolant 50 flows less easily in the left-to-right direction through gaps around the energy storage devices 10 farther from the first opening 37 than through the energy storage devices 10 closer to the first opening 37. However, by making the spacing around the storage devices 10 located on the outside in the left-right direction larger than the spacing around the storage devices 10 located in the center in the left-right direction as described above, it is possible to make the amount of coolant 50 filled in each storage device 10 more uniform.

[0046] Similar to the first power storage device group 100, the second power storage device group 110 has 20 power storage devices 10 arranged in pairs in a staggered pattern with a gap between each pair in the left-right direction. Meanwhile, in the second power storage device group 110, the gap between the power storage devices 10 arranged toward the center in the left-right direction is smaller than the gap between the power storage devices 10 arranged toward the outside in the left-right direction. That is, in the second power storage device group 110, the gap between the power storage devices 10 arranged toward the outside in the left-right direction is larger than the gap between the power storage devices 10 arranged toward the center in the left-right direction. That is, the coolant 50 flows more easily toward the outside in the left-right direction of the second power storage device group 110 than toward the center in the left-right direction. This configuration also makes it possible to more uniformly fill the coolant in each power storage device.

[0047] By arranging the first power storage device group 100 and the second power storage device group 110, each having a different arrangement of the power storage devices 10, inside the holder 30, it becomes easy to make the flow path of the coolant 50 meander inside the holder 30. As a result, the coolant 50 can easily flow throughout the entire interior of the holder 30, the amount of heat exchanged between the coolant 50 and the power storage devices 10 increases, and the power storage devices 10 can be cooled more efficiently.

[0048] 6 , the first power storage device group 100 and the second power storage device group 110 are arranged alternately in the front-to-rear direction. This makes it easier to make the flow path of the coolant 50 inside the holder 30 more tortuous. As a result, the coolant 50 flows more easily throughout the entire interior of the holder 30, increasing the amount of heat exchanged between the coolant 50 and the power storage devices 10 and enabling the power storage devices 10 to be cooled more efficiently.

[0049] As shown in FIG. 6 , the holder 30 is disposed approximately in the center of the interior of the case 40, and an outer peripheral housing chamber 49 for housing the coolant 50 is provided outside the holder 30. In other words, the outer peripheral housing chamber 49 is a space between the holder 30 and the case 40. The coolant 50 flowing out from the second opening 38 provided in the holder 30 flows into the outer peripheral housing chamber 49. By providing the outer peripheral housing chamber 49, heat exchange occurs between the power storage device 10 and the coolant disposed on the outer peripheral side of the holder 30 and the coolant 50 inside the outer peripheral housing chamber 49, making it easier to cool the power storage device 10 disposed on the outer peripheral side of the holder 30. Furthermore, when the upper current collecting plate 60 and the lower current collecting plate 61 are connected on the side surface of the holder 30, the coolant in the outer peripheral housing chamber 49 can cool the power storage device 10 via the current collecting plates. Furthermore, it is not necessary for all of the plurality of power storage devices 10 in the holder 30 to be housed inside the side wall portion that separates the outer peripheral accommodating chamber 49 from the inside of the holder 30. Some of the plurality of power storage devices 10 may be disposed outside the side wall portion, and these power storage devices 10 may be disposed in the outer peripheral accommodating chamber 49. In other words, the power storage devices 10 disposed outside the side wall portion may be in direct contact with the coolant 50 in the outer peripheral accommodating chamber 49. Note that the side wall portion does not need to completely block the flow of the coolant 50 between the inside of the holder and the outer peripheral accommodating chamber 49 via the side wall portion. Some coolant 50 may move through gaps in the side wall portion, for example.

[0050] 6 , a first opening 37 is provided in the center of the front surface 30a of the holder 30 in the left-right direction, allowing the coolant 50 to flow into the holder 30. In addition, two second openings 38 are provided in the rear surface 30b of the holder 30, allowing the coolant 50 inside the holder 30 to flow out of the holder 30. The first openings 37 and the second openings 38 are positioned offset from each other in the left-right direction. Specifically, the first opening 37 is provided in the center of the front surface 30a in the left-right direction, and the second openings 38 are provided on both left-right ends of the rear surface 30b.

[0051] The first opening 37 and the second opening 38 allow the coolant 50 that has flowed into the holder 30 through the first opening 37 to easily flow toward the outer periphery of the holder 30. In other words, the coolant that flows in the front-to-rear direction within the holder also easily moves in the left-to-right direction. This makes it easier to cool the power storage devices 10 that are arranged on the outer periphery of the holder 30, in addition to the power storage devices 10 that are arranged on the central side of the holder 30. In other words, if the second opening 38 were provided only on the left-to-right central side of the rear surface 30b, it would be difficult for the coolant 50 to flow toward the outer periphery of the holder 30, which may make it difficult to efficiently cool the power storage devices 10 that are arranged on the outer periphery of the holder 30.

[0052] In this embodiment, when the length of the rear surface 30b in the left-right direction in a top view is L, the second openings 38 are provided only within a range of 0.3L from both ends of the rear surface 30b in the left-right direction, and are not provided in the center of the rear surface 30b in the left-right direction. This allows the coolant 50 to flow more easily around the outer periphery of the holder 30 inside the holder 30, thereby enabling the power storage device 10 arranged on the outer periphery of the holder 30 to be more effectively cooled.

[0053] In this embodiment, the second opening 38 has a substantially rectangular shape in a plan view of the rear surface 30b, which is part of the sidewall of the holder 30. The rear surface 30b is, for example, a corrugated shape made up of multiple curved plates, and is formed on the ends of each curved surface in the left-right direction, excluding the center of each curved surface in the left-right direction. This configuration allows the coolant to flow over a wider area when it flows through the gap that is part of the outer peripheral housing chamber 49 between the rear surface 30b and the case 40.

[0054] Next, the connecting portion 70 will be described with further reference to Fig. 7. Fig. 7 is a cross-sectional view taken along line CC in Fig. 1 (a cross-sectional view in the front-rear direction of the center portion in the left-right direction), and is an enlarged view showing the vicinity of the connecting portion 70.

[0055] As shown in FIGS. 2 and 7 , the connecting portion 70 has a substantially cylindrical shape and is a member that connects the first opening 37 and the inlet 47. By providing the connecting portion 70, the coolant 50 that flows in through the inlet 47 flows directly into the holder 30 via the first opening 37. This prevents the coolant from preferentially filling the gap between the holder 30 and the case 40 rather than the gap within the holder 30. This increases the amount of coolant 50 that flows into the holder 30, allowing the power storage device 10 inside the holder 30 to be efficiently cooled. This effect is particularly effective when the gap between adjacent power storage devices 10 is smaller than the gap between the holder 30 and the case 40. The holder 30 may also be provided with a sidewall that accommodates the power storage device 10 and separates the inside of the holder 30 from the outside. This sidewall does not necessarily need to be liquid-tight. It is sufficient that the pressure loss is higher than that of the gap between the power storage devices 10. When the holder 30 is divided into an upper holder 31 and a lower holder 32, the side wall portion of the upper holder 31 and the side wall portion of the lower holder 32 may be aligned to form a single side wall surface.

[0056] The connecting portion 70 is made of, for example, a metal material including iron, aluminum, etc., or a resin material. The resin material that makes up the holder 30 can be used as the resin material that makes up the connecting portion 70.

[0057] The connecting portion 70 includes a cylindrical portion 71 inserted into the inlet portion 47 and an outer peripheral portion 72 formed on the outer periphery of the cylindrical portion 71. The cylindrical portion 71 has a cylindrical shape extending in the front-to-rear direction and is open at both ends. The outer peripheral portion 72 has a generally rectangular shape in a plan view of the front surface 40a of the case 40 and is formed around the entire periphery of the cylindrical portion 71. The outer peripheral portion 72 abuts against the outer surface of the case 40 and is fixed to the case 40 with screws (not shown) or the like. That is, the outer peripheral portion 72 is a portion for fixing the connecting portion 70 to the case 40. Note that the method for fixing the outer peripheral portion 72 to the case 40 is not limited thereto; for example, the outer peripheral portion 72 may be fixed to the case 40 with an adhesive or the like. A seal member 73, such as an O-ring, is provided between the outer peripheral portion 72 and the case 40 to improve the airtightness of the interior of the case 40.

[0058] As shown in Figure 7, the rear end of the cylindrical portion 71 is fitted into a recess 39 provided on the front surface 30a of the holder 30. The recess 39 is formed in an annular shape and holds the cylindrical portion 71 over its entire circumference. The shape of the recess 39 is not particularly limited as long as it can hold the cylindrical portion 71, and may have a depth (length in the front-rear direction) of 1 mm or more and 20 mm or less, for example. Note that the recess 39 may be configured to fit over a portion of the outer periphery of the cylindrical portion 71.

[0059] By fitting the connecting portion 70 into the recess 39, the connection between the connecting portion 70 and the first opening 37 can be achieved with a simple configuration due to the high pressure loss in the region between the connecting portion 70 and the recess 39. In other words, if the recess 39 is not provided, a component for connecting the connecting portion 70 and the holder 30 is required, and a sealing member may also be required to ensure the sealing of the connection point. From the perspective of suppressing increases in manufacturing costs and facilitating the connection process, it is preferable to reduce the number of components constituting the battery pack 1. In this embodiment, the recess 39 is provided near the first opening 37. However, this recess may also be formed near the inlet of the case 40, with a portion of the connecting portion 70 fitted into this recess.

[0060] In this embodiment, the connecting portion 70 is formed as a separate member from the holder 30 and the case 40, but the connecting portion 70 may be formed integrally with the holder 30 or the case 40.

[0061] As described above, the battery pack 1 of this embodiment includes the connecting portion 70 that connects the inlet portion 47 provided in the case 40 with the first opening 37 provided in the holder 30. This increases the amount of coolant 50 that flows into the holder 30, allowing the power storage device 10 inside the holder 30 to be efficiently cooled. As a result, the reliability of the battery pack 1 can be improved.

[0062] The battery pack 1 of this embodiment also includes a connecting portion 70 that connects the inlet portion 47 provided in the case 40 with the first opening 37 provided in the holder 30. The connecting portion 70 is sandwiched in a recess 39 provided in the front surface 30a of the holder 30. This allows the amount of coolant 50 flowing into the holder 30 to be increased without increasing the number of parts, thereby efficiently cooling the power storage device 10 inside the holder 30. As a result, the reliability of the battery pack 1 can be improved.

[0063] The present disclosure is not limited to the above-described embodiment, and various improvements and modifications are possible within the scope of the claims of the present application and their equivalents. For example, in the above-described embodiment, the battery pack 1 is provided with the outer circumferential housing chamber 49 that houses the coolant 50 on the outer periphery of the holder 30, but the outer circumferential housing chamber 49 does not have to be provided.

[0064] Furthermore, in the above embodiment, the energy storage device 10 is arranged so that the sealing body 16 is on the lower side, but the energy storage device 10 may also be arranged so that the sealing body 16 is on the upper side, i.e., so that the bottom 15a of the outer can 15 is on the lower side.

[0065] In the above embodiment, the connecting portion 70 is joined to the holder 30 by being sandwiched in a recess 39 provided on the front surface 30a of the holder 30. However, the joining method between the connecting portion 70 and the holder 30 is not limited to this. For example, as shown in FIG. 8 , a protrusion 80 protruding forward may be provided on the periphery of the first opening 37, and the outer peripheral surface of the protrusion 80 may be joined to the inner peripheral surface of the connecting portion 70 (cylindrical portion 71). Alternatively, the inner peripheral surface of the protrusion 80 may be joined to the outer peripheral surface of the connecting portion 70. A sealing member 74 such as an O-ring may be provided between the connecting portion 70 and the holder 30 to improve the sealing performance of the interior of the connecting portion 70. A cylindrical restraining ring 75 may be provided between the sealing member 74 and the protrusion 80. This configuration increases the contact area compared to a configuration in which an O-ring is directly abutted against the protrusion 80 for sealing, enabling a more liquid-tight seal. An adhesive may be interposed between the restraining ring 75 and the protrusion 80. The effect of this restraint ring 75 is particularly effective when the first opening 37 is formed by combining two notches (the first notch in the upper holder 31 and the second notch in the lower holder 32) in the upper holder 31 and the lower holder 32. When a protrusion 80 near the first notch and a protrusion near the second notch are combined to form a cylindrical protrusion, the restraint ring 75 easily covers the joint between the protrusions. Furthermore, the opening at the holder-side end of the connecting portion 70 may have its inner circumferential surface positioned outside the O-ring, pressing the O-ring inward. This increases the reliability of the sealing provided by the O-ring.

[0066] Furthermore, in the above embodiment, the energy storage devices 10 are arranged with a predetermined gap therebetween, but the arrangement of the energy storage devices 10 is not limited to this. For example, as shown in Fig. 9 , the energy storage devices 10 may be arranged so that the intervals between the energy storage devices 10 in the left-right direction are approximately the same. In the example shown in Fig. 9 , the energy storage devices 10 are arranged periodically on the lattice points of a triangular lattice. In this case, it is easy to reduce the size of the battery pack 1. Note that the energy storage devices 10 may also be arranged periodically on the lattice points of a square lattice.

[0067] In the above embodiment, the second opening 38 is not provided in the region toward the center in the left-right direction of the rear surface 30b of the holder 30, but the arrangement of the second opening 38 is not limited to this. For example, as shown in Fig. 9, the second opening 38 may be provided in the region toward the center in the left-right direction of the rear surface 30b of the holder 30, in addition to the outer regions in the left-right direction of the rear surface 30b of the holder 30. Furthermore, the second opening 38 may be provided only in the region toward the center in the left-right direction of the rear surface 30b of the holder 30.

[0068] The present disclosure will be further described with reference to the following embodiments. Configuration 1: An energy storage module including: a plurality of energy storage devices; a holder that holds the plurality of energy storage devices; a coolant that immerses the plurality of energy storage devices within the holder; and a case that houses the holder and has an inlet portion through which the coolant flows from the outside. Configuration 2: The energy storage module according to configuration 1, wherein the holder has an opening that is disposed opposite the inlet portion and through which the coolant flows into the holder, and further includes a connecting portion that connects the inlet portion to the opening. Configuration 3: The energy storage module according to configuration 1 or 2, wherein the connecting portion has a cylindrical portion that is inserted into the inlet portion and an outer circumferential portion formed on the outer circumferential surface of the cylindrical portion. Configuration 4: The energy storage module according to configuration 3, wherein at least a portion of the outer circumferential portion abuts against the outer surface of the case. Configuration 5: The energy storage module according to configuration 3 or 4, wherein a seal member is provided between the outer circumferential portion and the outer surface of the case. Configuration 6: The power storage module according to any one of configurations 1 to 5, wherein the case includes an outflow section that allows the coolant to flow to the outside. Power storage module. Configuration 7: The power storage module according to configuration 6, wherein the opening is a first opening, and a second opening is provided on the outflow section side separately from the first opening, and the second opening connects a space within the holder to a space within the case. Configuration 8: The power storage module according to any one of configurations 1 to 7, wherein the holder has a side wall section that separates the holder from an interior of the holder within the case. Configuration 9: The power storage module according to any one of configurations 1 to 8, wherein the distance between a pair of adjacent power storage devices among the plurality of power storage devices is smaller than the distance between the holder and the case.and a cylindrical inlet wall portion formed on an edge of the first notch and a cylindrical inlet wall portion of the opening, the cylindrical inlet wall portion being aligned with each other ... Configuration 12: The energy storage module according to configuration 1, wherein the holder has an opening provided opposite the inlet portion and allowing the coolant to flow into the holder, and further includes a connecting portion connecting the inlet portion and the opening, the connecting portion being clamped in a recess provided in the holder.Configuration 13: The energy storage module according to configuration 12, wherein the connecting portion has a cylindrical portion inserted into the inlet portion and an outer circumferential portion formed on the outer periphery of the cylindrical portion.Configuration 14: The energy storage module according to configuration 13, wherein the outer circumferential portion abuts against an outer surface of the case.Configuration 15: The energy storage module according to any one of configurations 12 to 14, wherein the recess is provided in an annular shape.

[0069] REFERENCE SIGNS LIST 1 battery pack, 10 power storage device, 11 positive electrode, 12 negative electrode, 13 separator, 14 electrode body, 15 outer can, 15a bottom, 15b side surface, 15c grooved portion, 15d opening, 16 sealing body, 17 gasket, 18, 19 insulating plate, 20 positive electrode lead, 21 negative electrode lead, 30 holder, 30a front surface, 30b rear surface, 31 upper holder, 32 lower holder, 33, 34 battery holding portion, 35, 36 through hole, 37 first opening (opening), 38 second opening, 39 recess, 40 case, 40a front surface, 40b rear surface, 41 main wall, 42, 43, 44, 45 side wall, 46 upper lid, 47 inlet portion, 48 outlet portion, 49 outer peripheral storage chamber, 50 Coolant, 51 Rib, 52 Fixing portion, 60 Upper current collecting plate, 61 Lower current collecting plate, 62, 63 Lead, 70 Connecting portion, 71 Cylindrical portion, 72 Outer periphery, 73, 74 Seal member, 75 Restraining ring, 80 Protrusion, 100 First power storage device group, 110 Second power storage device group

Claims

1. An energy storage module comprising: a plurality of energy storage devices; a holder that holds the plurality of energy storage devices; a coolant that immerses the plurality of energy storage devices within the holder; and a case that houses the holder and has an inlet portion that allows the coolant to flow in from the outside.

2. An energy storage module according to claim 1, wherein the holder has an opening provided opposite the inlet portion and allowing the coolant to flow into the holder, and further comprises a connecting portion connecting the inlet portion and the opening.

3. An energy storage module according to claim 2, wherein the connecting portion has a cylindrical portion inserted into the inlet portion, and an outer peripheral portion formed on the outer peripheral surface of the cylindrical portion.

4. The energy storage module according to claim 3, wherein at least a portion of the outer periphery abuts against the outer surface of the case.

5. The energy storage module according to claim 3, wherein a seal member is provided between the outer peripheral portion and the outer surface of the case.

6. An electric storage module according to claim 2, wherein the case has an outlet portion for allowing the coolant to flow out.

7. An energy storage module according to claim 6, wherein the opening is a first opening, and a second opening is provided on the outlet side separate from the first opening, and the second opening connects the space within the holder with the space within the case.

8. An energy storage module according to claim 2, wherein the holder has a side wall portion that separates the inside of the holder from the outside of the holder within the case.

9. The energy storage module according to claim 2, wherein the distance between a pair of adjacent energy storage devices among the plurality of energy storage devices is smaller than the distance between the holder and the case.

10. An energy storage module as claimed in claim 2, wherein the holder includes an upper holder that houses one end of one of the plurality of energy storage devices and a lower holder that holds the other end of the energy storage device, and the opening is configured by aligning a first notch formed in the upper holder with a second notch formed in the lower holder.

11. An energy storage module according to claim 10, wherein an inlet wall portion is formed on each edge of the first cutout and an edge of the second cutout, and the inlet wall portions are arranged side by side to form an inlet tubular portion in the opening, and the energy storage module further comprises a tubular restraining ring surrounding the outer circumferential surface of the inlet tubular portion, and an O-ring surrounding the outer circumferential surface of the restraining ring.

12. An energy storage module as claimed in claim 1, wherein the holder has an opening, which is provided opposite the inlet portion, for allowing the coolant to flow into the holder, and further comprises a connecting portion that connects the inlet portion and the opening, and the connecting portion is clamped in a recess provided in the holder.

13. An energy storage module according to claim 12, wherein the connecting portion has a cylindrical portion inserted into the inlet portion, and an outer peripheral portion formed on the outer periphery of the cylindrical portion.

14. The energy storage module according to claim 13, wherein the outer peripheral portion abuts against the outer surface of the case.

15. The energy storage module according to claim 12, wherein the recess is provided in a circular ring shape.

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