Power storage module

Abstract

A power storage module (10) comprises: at least one power storage device (20); a case (40) in which the at least one power storage device (20) is accommodated; a cooling liquid (50) in which a plurality of power storage devices (20) are immersed inside the case (40); cooling liquid piping (61) which is connected to the case (40) and through which the cooling liquid (50) passes; and an exhaust pipe (70) that is for exhausting gas inside the case (40) from the case (40) and that is thermally connected to the cooling liquid piping (61).

Description

Energy storage module

[0001] The present disclosure relates to an energy storage module.

[0002] An electric storage module is used as a power source having a plurality of electric storage devices. The electric storage module may include a plurality of electric storage devices, a case for accommodating the plurality of electric storage devices, and a coolant for immersing the plurality of electric storage devices within the case (see, for example, Patent Document 1).

[0003] Patent No. 6256439

[0004] There is a demand for further improvements in the reliability of energy storage modules.

[0005] The energy storage module according to the present disclosure is characterized by comprising at least one energy storage device, a case in which the at least one energy storage device is housed, a coolant in which the plurality of energy storage devices are immersed within the case, a coolant pipe connected to the case and through which the coolant passes, and an exhaust pipe that exhausts gas within the case from the case and is thermally connected to the coolant pipe.

[0006] According to the energy storage module of the present disclosure, reliability can be improved.

[0007] Fig. 1 is a side cross-sectional view of an electric storage module according to an embodiment; Fig. 2 is a side cross-sectional view of an electric storage device according to an embodiment; Fig. 3 is a perspective view of an exhaust pipe according to an embodiment; Fig. 4 is a schematic view of an exhaust pipe according to another embodiment;

[0008] An example of an embodiment of the present disclosure will be described in detail below. In the following description, specific shapes, materials, directions, numerical values, etc. are examples for facilitating understanding of the present disclosure, and can be appropriately changed according to the application, purpose, specifications, etc.

[0009] [Overall Configuration of Energy Storage Module] An energy storage module 10 as an example of an embodiment will be described with reference to FIG.

[0010] The power storage module 10 is mounted on an electric vehicle as a power source for the motor that drives the electric vehicle. However, the power storage module of the present disclosure is not limited to being mounted on an electric vehicle, and may be used as a power source for motor-driven electric devices such as power tools, power-assisted bicycles, electric motorcycles, electric wheelchairs, electric tricycles, and electric carts. Furthermore, the use of the power storage module of the present disclosure is not limited, and may 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.

[0011] The energy storage module 10 includes a plurality of (at least one) energy storage devices 20, a case 40 that houses the plurality of energy storage devices 20, a coolant 50 that immerses the plurality of energy storage devices 20 inside the case 40, a coolant piping 61 that is connected to the case 40 and through which the coolant 50 passes, and an exhaust pipe 70 that exhausts gas inside the case 40 from the case 40 and is thermally connected to the coolant piping 61.

[0012] The multiple power storage devices 20 may be packed as densely as possible within the power storage module 10, taking safety into consideration, and adjacent power storage devices 20 may be arranged in close proximity to each other. For example, the power storage devices 20 may be arranged such that six power storage devices 20 surround one power storage device 20 in a plan view (or arranged in a staggered pattern). Alternatively, the multiple power storage devices 20 may be arranged such that the power storage devices 20 closest to each other are located on all four sides. Details of the power storage device 20 will be described later. Note that the power storage module 10 of the present disclosure may include only one power storage device 20.

[0013] The upper side of the power storage device 20 is held by an upper holder 31. The upper holder 31 is made of, for example, a thermoplastic resin. Thermoplastic resins are broadly classified into general-purpose plastics and engineering plastics, and examples of such resins include polycarbonate, polyethylene, polypropylene, polyamide, and ABS.

[0014] A positive current collector plate 32 is disposed on the upper surface of the upper holder 31. The positive current collector plate 32 is a member that connects positive terminals serving as first electrode terminals of the power storage device 20, which will be described later. The positive current collector plate 32 is immersed in the coolant 50 inside the case 40. The positive current collector plate 32 is formed from a conductive metal plate.

[0015] The lower side of the power storage device 20 is held by a lower holder 33. The lower holder 33 is made of, for example, a thermoplastic resin. Thermoplastic resins are broadly classified into general-purpose plastics and engineering plastics, and examples of such resins include polycarbonate, polyethylene, polypropylene, polyamide, and ABS.

[0016] A negative current collector 34 is disposed on the lower surface of the lower holder 33. The negative current collector 34 is a member that connects negative terminals serving as second electrode terminals of the power storage device 20, which will be described later. The negative current collector 34 is immersed in the coolant 50 inside the case 40. The negative current collector 34 is formed of a conductive metal plate. The positive current collector 32 and the negative current collector 34 may both be disposed together at a common end of the power storage device 20.

[0017] As described above, the case 40 houses a plurality of power storage devices 20. The case 40 is made of a metal such as aluminum or a resin, and is formed into a substantially rectangular parallelepiped shape. The case 40 can protect the power storage devices 20 housed therein from dust and water.

[0018] As described above, the coolant 50 immerses the plurality of power storage devices 20 inside the case 40. In the power storage module 10, the coolant 50 can cool the power storage devices 20. This can improve the reliability of the power storage module 10. The coolant 50 has insulating properties. This can prevent current leakage from one power storage device 20 to another power storage device 20 via the coolant 50. The coolant 50 may be, for example, insulating oil, transformer oil, silicone oil, or a fluorine-based inert liquid such as hydrofluoroether.

[0019] As described above, the coolant piping 61 is connected to the case 40, and the coolant 50 passes through the coolant piping 61. The coolant piping 61 is part of the piping that constitutes the coolant circulation path 60. In the coolant circulation path 60, the coolant 50 is circulated by a pump device or the like, thereby circulating the coolant 50 inside the case 40. Note that the coolant circulation path 60 may be provided with a heat exchanger such as heat exchange fins.

[0020] As described above, exhaust pipe 70 exhausts gas from case 40 when an abnormality occurs in power storage device 20, and is thermally connected to coolant pipe 61. In addition, exhaust pipe 70 is wrapped around connection portion 61A of coolant pipe 61 with case 40. Details of exhaust pipe 70 will be described later.

[0021] [Power Storage Device] The power storage device 20 as an example of an embodiment will be described with reference to FIG.

[0022] In this embodiment, a cylindrical lithium-ion secondary battery is used as the power storage device 20, but a nickel-metal hydride battery, a capacitor, or the like may also be used. The power storage device 20 includes an electrode group 24, for example, a band-shaped positive electrode 21 and a band-shaped negative electrode 22 wound together with a band-shaped separator 23 interposed therebetween; a cylindrical outer can 25 that houses the electrode group 24 together with an electrolyte; a sealing member 26 that insulates and seals an opening provided at one axial end of the outer can 25; a foil-shaped positive electrode tab 27 that electrically connects the positive electrode 21 to the sealing member 26; and a negative electrode tab 28 that electrically connects the negative electrode 22 to the outer can 25. An insulating gasket 29 may be disposed between the outer periphery of the sealing member 26 and the inner circumferential surface of the opening of the outer can 25. Note that the outer casing of the power storage device of the present disclosure is not limited to the cylindrical outer can 25, and may be a rectangular outer can or a pouch-shaped outer casing.

[0023] An annular groove 25A is formed on the outer peripheral surface of the outer can 25, on the opening side. This groove 25A is formed as an annular protrusion on the inner peripheral surface of the outer can 25. The gasket 29 and sealing body 26 are disposed on this annular protrusion within the outer can 25. Furthermore, the opening end of the outer can 25 is crimped so as to bend toward the inside of the outer can 25, with the gasket 29 disposed on the inner peripheral side. The crimped opening end and the protrusion sandwich the sealing body 26 in the axial direction via the gasket 29, thereby sealing the opening of the outer can 25.

[0024] The sealing body 26 is provided with a current interrupter (CID) or a safety valve that ruptures when the pressure inside the outer can 25 reaches or exceeds the operating pressure. An insulating plate 30 is provided between the electrode group 24 and the bottom surface 25B of the outer can 25 or between the electrode group 24 and the protrusion (groove 25A) to insulate the electrode group 24 from the outer can 25. The positive electrode tab 27 extends through a through-hole formed in the insulating plate 30. The negative electrode tab 28 may extend through a through-hole formed in the insulating plate 30 or may extend around the insulating plate 30.

[0025] In the energy storage device 20, a positive electrode terminal as a first electrode terminal is provided on the top surface of the sealing body 26, and a negative electrode terminal as a second electrode terminal is provided on the bottom surface 25B of the outer can 25. A positive electrode lead of a positive electrode current collector 32 is joined by welding to the top surface of the sealing body 26, which is the positive electrode terminal as the first electrode terminal. A negative electrode lead of a negative electrode current collector 34 is joined by welding to the bottom surface 25B of the outer can 25, which is the negative electrode terminal as the second electrode terminal.

[0026] [Exhaust Pipe] An exhaust pipe 70 as an example of an embodiment will be described with reference to Figures 1 and 3. In Figure 3, for ease of understanding, the top surface of the case 40 is open, and the upper holder 31, the positive electrode current collector plate 32, and the coolant 50 are omitted.

[0027] As described above, the exhaust pipe 70 exhausts gas from the case 40 when an abnormality occurs in the power storage device 20, for example, and is thermally connected to the coolant pipe 61. The exhaust pipe 70 is also wrapped around a connection portion 61A of the coolant pipe 61 with the case 40. As will be described in detail later, the exhaust pipe 70 can reduce white smoke contained in the gas exhausted from the case 40 when an abnormality occurs in the power storage device 20. Note that the gas discharged through the exhaust pipe 70 does not necessarily have to be due to an abnormality (temperature rise) in the power storage device 20.

[0028] Here, abnormalities in the power storage device 20 include thermal runaway of the power storage device 20. When thermal runaway occurs in the power storage device 20, the power storage device 20 becomes hot, and the coolant 50 vaporizes in a high-temperature, high-pressure environment and is exhausted from the case 40. When thermal runaway occurs in the power storage device 20, the coolant 50 becomes mist-like (atomized liquid) in a high-temperature, high-pressure environment and is exhausted from the case 40.

[0029] In other words, the gas in the case 40 when the storage device 20 experiences thermal runaway includes the coolant 50 that evaporates when the storage device 20 reaches a high temperature under a high-temperature and high-pressure environment, the coolant 50 that becomes mist-like (atomized liquid) under a high-temperature and high-pressure environment, and other gases.

[0030] As will be described in detail later, the exhaust pipe 70 can collect the coolant 50 mist contained in the gas exhausted from the case 40 during thermal runaway of the power storage device 20, thereby reducing the amount of coolant 50 mist contained in the gas. This can reduce white smoke contained in the gas, thereby improving the reliability of the power storage module 10.

[0031] Furthermore, by configuring the exhaust pipe 70 and the coolant pipe 61 as a single assembly component and connecting them to the case 40 at the same time during the assembly process of the energy storage module 10, the number of steps required to assemble the energy storage module 10 can be reduced.

[0032] The exhaust pipe 70 has an exhaust pipe inlet 70A that forms the inlet of the exhaust pipe 70, a wound portion 70B that is wound around the coolant piping 61, and an exhaust pipe outlet 70C that forms the outlet of the exhaust pipe 70.

[0033] The exhaust pipe inlet 70A is a portion that forms the inlet of the exhaust pipe 70. The exhaust pipe inlet 70A is connected to the upper part of the interior of the case 40. A pressure release valve 71 is provided at the exhaust pipe inlet 70A. In other words, the pressure release valve 71 is provided between the exhaust pipe 70 and the case 40.

[0034] The pressure release valve 71 is a valve that opens when the pressure inside the case 40 is equal to or greater than a set pressure value. The pressure release valve 71 allows gas to be exhausted from the exhaust pipe inlet 70A only when the pressure inside the case 40 becomes high pressure during thermal runaway of the power storage device 20. The pressure release valve 71 may be, for example, a valve that can exhaust only gas. The pressure release valve 71 may be, for example, a waterproof, breathable membrane.

[0035] The wound portion 70B is a portion wound around the coolant pipe 61. More specifically, it is wound around the connection portion 61A of the coolant pipe 61 on the inlet side with the case 40. Although the exhaust pipe 70 of this embodiment is wound around the connection portion 61A of the coolant pipe 61 on the inlet side with the case 40, it may also be wound around the connection portion 61A on the outlet side. It is preferable that the wound portion 70B be wound at least three times.

[0036] The above-described configuration thermally connects the wound portion 70B and the coolant pipe 61. It is preferable that the wound portion 70B and the coolant pipe 61 are in contact with each other. The wound portion 70B and the coolant pipe 61 may be joined by brazing, welding, or the like.

[0037] The wound portion 70B is thermally connected to the coolant pipe 61, and is therefore capable of cooling the vaporized coolant 50 contained in the gas during thermal runaway of the power storage device 20. When the vaporized coolant 50 is cooled, it may turn into mist-like coolant 50.

[0038] Furthermore, the winding portion 70B is wound around the coolant pipe 61, thereby causing the gas to swirl and move. This allows the coolant mist 50 contained in the gas to be centrifuged and condensed. This allows the coolant mist 50 to be collected in the exhaust pipe 70. Note that the coolant mist 50 contained in the gas also includes coolant mist 50 that has been cooled after vaporization.

[0039] The exhaust pipe outlet 70C is a portion that forms the outlet of the exhaust pipe 70. The exhaust pipe outlet 70C is arranged so that the exhaust pipe outlet 70C faces downward outside the case 40. This makes it possible to prevent the gas from diffusing over a wide area outside the case 40.

[0040] Another embodiment of the present invention will be described with reference to Fig. 4. In the following description, the same reference numerals will be used to designate components that are common to the above-described power storage module 10, and the description thereof will be omitted.

[0041] The coolant pipe 61 connects multiple (two in the example of FIG. 4 ) cases 40 in parallel. More specifically, the coolant pipe 61 branches into multiple (two in the example of FIG. 4 ) pipes, each connected to a respective case 40.

[0042] The exhaust pipe 80 connects multiple cases 40 in parallel. More specifically, the exhaust pipe 80 has exhaust pipe inlets 80A connected to the interior and upper parts of each case 40 where they join together, a wound portion 80B wound around the base end of the coolant piping 61 before it branches, and an exhaust pipe outlet 80C facing downward outside the case 40. Each exhaust pipe inlet 80A is provided with a pressure release valve. The exhaust pipe inlet 80A, wound portion 80B, and exhaust pipe outlet 80C have the same configurations as the exhaust pipe inlet 70A, wound portion 70B, and exhaust pipe outlet 70C described above, and therefore will not be described here.

[0043] [Summary] The present disclosure is further described by the following embodiments. Configuration 1: An energy storage module comprising: at least one energy storage device; a case that houses the at least one energy storage device; a coolant that immerses multiple energy storage devices within the case; a coolant pipe that is connected to the case and through which the coolant passes; and an exhaust pipe that exhausts gas within the case from the case and is thermally connected to the coolant pipe. Configuration 2: The energy storage module according to configuration 1, wherein the exhaust pipe is wound around the coolant pipe. Configuration 3: The energy storage module according to configuration 1 or 2, wherein a pressure relief valve is provided between the exhaust pipe and the case, which exhausts air when the case is at or above a predetermined pressure. Configuration 4: The energy storage module according to any of configurations 1 to 3, wherein the exhaust pipe is arranged with an exhaust pipe outlet facing downward. Configuration 5: The electric storage module according to any one of configurations 1 to 4, wherein the coolant pipe connects a plurality of the cases in parallel, and the exhaust pipe connects a plurality of the cases in parallel.

[0044] It should be noted that the present disclosure is not limited to the above-described embodiments and their variations, and it goes without saying that various modifications and improvements are possible within the scope of the matters described in the claims of the present application.

[0045] REFERENCE SIGNS LIST 10 Energy storage module, 20 Energy storage device, 21 Positive electrode, 22 Negative electrode, 23 Separator, 24 Electrode group, 25 Outer can, 25A Groove, 25B Bottom surface, 26 Sealing body, 27 Positive electrode tab, 28 Negative electrode tab, 29 Gasket, 30 Insulating plate, 31 Upper holder, 32 Positive electrode current collector, 33 Lower holder, 34 Negative electrode current collector, 40 Case, 50 Coolant, 60 Coolant circulation path, 61 Coolant piping, 61A Connection, 70 Exhaust pipe, 70A Exhaust pipe inlet, 70B Winding portion, 70C Exhaust pipe outlet, 71 Pressure release valve, 80 Exhaust pipe, 80A Exhaust pipe inlet, 80B Winding portion, 80C Exhaust pipe outlet

Claims

1. An energy storage module comprising: at least one energy storage device; a case that houses the at least one energy storage device; a coolant that immerses a plurality of the energy storage devices within the case; a coolant pipe that is connected to the case and through which the coolant passes; and an exhaust pipe that exhausts gas within the case from the case and is thermally connected to the coolant pipe.

2. The electric storage module according to claim 1, wherein the exhaust pipe is wound around the coolant pipe.

3. An electricity storage module according to claim 1 or 2, wherein a pressure release valve is provided between the exhaust pipe and the case, for venting when the case is at or above a predetermined pressure.

4. The energy storage module according to any one of claims 1 to 3, wherein the exhaust pipe is arranged with an exhaust pipe outlet facing downward.

5. An electric storage module according to any one of claims 1 to 4, wherein the coolant pipe connects a plurality of the cases in parallel, and the exhaust pipe connects a plurality of the cases in parallel.

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